Human Molecular Genetics, 2000, Vol. 9, No. 11 1633-1639
© 2000 Oxford University Press
Expression of the PTEN tumour suppressor protein during human development
1Clinical Cancer Genetics and Human Cancer Genetics Programs, Comprehensive Cancer Center, and Division of Human Genetics, Department of Internal Medicine, Ohio State University, Columbus, OH 43210, USA, 2Département de Génétique et Unité INSERM U-393, Hôpital Necker-Enfants Malades, Paris, France, 3Massachusetts Institute of Technology, Cambridge, MA, USA and 4Cancer Research Campaign Human Cancer Genetics Research Group, University of Cambridge, Cambridge CB2 2QQ, UK
Received 6 March 2000; Revised and Accepted 25 April 2000.
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ABSTRACT |
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The tumour suppressor gene PTEN, localized to 10q23.3, is the susceptibility gene for Cowden syndrome (CS) and Bannayan–Riley–Ruvalcaba (BRR) syndrome, two hamartoma syndromes with an increased risk of breast and thyroid tumours. Somatic mutations have been found in a variety of human tumours. Functional studies have revealed that PTEN plays a fundamental role in cellular growth, death, adhesion and migration. RNA in situ hybridization using the pten coding region in mouse embryos showed ubiquitous transcription, providing evidence that pten could play a versatile role throughout murine development. Nothing is known regarding the pattern of PTEN expression during human development. Here, we present the pattern of PTEN expression during human development using a specific monoclonal antibody and examine the relationship of the temporal and spatial expression pattern to the clinical manifestations of CS and BRR, the somatic genetic data in sporadic cancers, the murine knockout models and the RNA expression data in mouse embryos. We observed mainly high-level PTEN expression in tissues (e.g. skin, thyroid and central nervous system) known to be involved in CS and BRR. In addition, we identified tissues (e.g. peripheral nervous system, autonomomic nervous system and upper gastrointestinal tract) with high PTEN expression not commonly known to play a role in these syndromes nor in sporadic tumorigenesis in those organs. This knowledge may help in identifying roles for PTEN which, as of today, are unknown or even unsuspected.
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INTRODUCTION |
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It is not uncommon for a gene to have been isolated and linked directly to neoplasia, and subsequently found to play a universal and profound role in normal development. Often, examining how a gene is temporally and spatially expressed during development can, in turn, lend further clues to its role in tumorigenesis.
The dual-specificity phosphatase gene PTEN (also known as MMAC1 and TEP1) (1–3) is no exception. Localized to 10q23.3, PTEN is the susceptibility gene for Cowden syndrome (CS, MIM158350), which is characterized by multiple hamartomas and a high risk of breast, thyroid and endometrial cancers, and a susceptibility gene for Bannayan–Riley–Ruvalcaba syndrome (BRR, MIM153480), a congenital hamartoma syndrome characterized by macrocephaly, lipomatosis, haemangiomas and speckled penis, and possibly for Proteus-like syndromes as well (4–8). We have, therefore, grouped these three syndromes with PTEN mutations as the PTEN Hamartoma Tumour Syndrome (PHTS) (7). Further, there has been a greater or lesser degree of deletion and/or intragenic PTEN mutation in a broad range of sporadic neoplasias (9–12). Even prior to the identification of PTEN as the susceptibility locus, it was already predicted, based on the clinical manifestation of CS patients, that PTEN would play an important role in development and apoptosis (13,14). Subsequently, various functional and animal modelling experiments have demonstrated that PTEN plays a role in apoptosis and G1 cell cycle arrest (15–17). There have been suggestions that PTEN might also interact with the FAK pathway and the MAP kinase pathway (18,19).
Given the protean manifestations of the syndromes in which PTEN is implicated and the role of PTEN in the fundamental control of cellular growth, death, adhesion and migration, it is almost certain that PTEN plays some role during development. Nothing is known regarding the pattern of PTEN expression during human development. RNA in situ hybridization using the pten coding region in mouse embryos showed ubiquitous transcription, providing evidence that pten could play a versatile role throughout murine development (20,21). This approach, however, would lead to some pitfalls if performed in human tissue due to the existence of a highly conserved pseudogene, which has been shown to be transcribed (but not translated) in a tissue-specific manner (12,22–26). Further, it has become obvious that there are significant mouse–human differences in the expression of various genes during development, differences that cannot be predicted beforehand (27). Thus, it would be more desirable to examine expression during human development at the protein level. Here, we present the pattern of PTEN expression in human development using a specific monoclonal antibody and examine the relationship of the temporal and spatial expression pattern to the clinical manifestations of the PHTS (7), the somatic genetic data in sporadic cancers, the murine knockout models and the RNA expression data in mouse embryos.
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RESULTS AND DISCUSSION |
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Relatively early in development, many tissues revealed PTEN expression (e.g. mesonephros, stomach, liver, central and peripheral nervous systems) and the intensity of immunostaining correlated with cell density (Fig. 1B–C). During further development, PTEN expression became more distinct in specific tissues (e.g. Fig. 1I and L).
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, peripheral nerve(s). (B) Transverse section (x4), day 41: a, aorta; mn, mesonephros; s, stomach; e, oesophagus; l, liver. (C) Transverse section (x4), day 41: c, spinal cord; g, spinal ganglion; 
, telencephalon; 
, foramen caecum; t, thyroid gland; h, heart. (E) Transverse section (x4), human fetus, 13 weeks old: t, thyroid gland; r, tracheal cartilage; e, oesophagus; 
, vagal nerve. (F) Transverse section (x20), close-up of (E). (G–N) Human fetus, 17 weeks old. (G) Colon (x20): 
, glomerulus; 
, tubule(s). (M) Thymus (x20). (N) Skin (x40): Nervous system
Amongst all organ systems, the strongest overall PTEN protein expression was observed throughout the central and peripheral nervous systems (Fig. 1A and C–E). This very high PTEN expression was maintained throughout human development in all embryos and fetuses investigated (data not shown). High pten expression in the central nervous system has also been observed in mice using RNA in situ hybridization (20,21). Relatively high PTEN expression, but certainly not with the intensity noted in the developing brain, continues in the normal human adult brain (X.P. Zhou and C. Eng, unpublished observations). Somatic PTEN mutations are frequently found in brain tumours of the glioneural line, the frequency of which increases with grade such that the highest frequencies of monoallelic and biallelic structural mutations occur in glioblastoma multiforme (GBM) (9,10,28). However, GBM is only rarely seen in patients with CS and it is unclear if it is even a true component of PHTS (29). In contrast, mental retardation and macrocephaly (megencephaly) are true components of CS, occurring in ~25% of cases, and both are major signs in patients with BRR, occurring in a great majority of such cases (7,30,31). These observations seem to indicate that PTEN plays an important role during the development of the central nervous system. Certainly, from the prominent and persistent expression throughout human development, we would predict that any dysfunction or haploinsufficiency would lead to the inability to undergo appropriate G1 arrest and/or apoptosis during nervous system moulding, and macrocephaly (megencephaly) and mental retardation are plausible outcomes. Tumour formation, however, seems to require additional genetic and/or epigenetic events over mere haploinsufficiency or single allele defects, at least in the central nervous system. This hypothesis is partially borne out by the identification of GBM, albeit sporadic, with ‘two hits’ (9,32–34) and the absence of brain tumours in hemizygous pten knockout mice (35–37).
Somehow, intriguingly, no disorders or tumours affecting the peripheral nervous system have been firmly established as components of CS or BRR, although anecdotal associations with peripheral neuromas or neurofibromas have been reported [reviewed by Eng and Parsons (38)]. In light of our observations in the developing human and given these anecdotal reports, a closer examination of the peripheral nervous system in these patients may be warranted.
High PTEN protein expression has also been found in the autonomic nervous system of the gastrointestinal tract (Fig. 1E and G–H). It is interesting that PTEN might play an important role during the development of the human autonomic nervous system but to date, no functional or developmental disorders have been described in patients with CS or BRR except anecdotal obervations of ganglioneuromatosis of the gut (C. Eng, unpublished observations; ref. 39). If loss-of-function PTEN mutations can be associated with ganglioneuromatosis, then it may be speculated that the converse, activating or gain-of-function mutations of PTEN (which, to date, have not been reported) would lead to inappropriate apoptosis of cells in tissues with strong PTEN expression. If they occur in germline cells, these mutations may cause premature intrauterine death. If the mutations are not lethal or if they are present in mosaic cells, they may cause improper development of the tissues and organs with strong PTEN expression.
Thyroid gland
PTEN protein expression was high in the thyroid gland (Fig. 1E–F) even during early development (Fig. 1D). Of note, normal thyroid tissue in adults shows high PTEN expression (40). Reflecting the strong expressional pattern during human development, thyroid gland abnormalities are common in patients with CS and BRR. Actually, up to 67% of patients with CS develop benign thyroid disorders, including hamartomas and tumours, and the risk for developing malignant thyroid tumours is ~5–10% (reviewed in ref. 29). Two of the three mouse knockout models also suggest an important role of pten in the development of thyroid disorders, although the thyroid lesions noted in these mice are not similar to those seen in human CS or BRR (35,37). While somatic mutations have only been found in a minority of thyroid carcinomas (41,42), loss of heterozygosity has been described in ~25% of benign thyroid tumours and differentiated thyroid carcinomas (40,42,43). Why sporadic thyroid neoplasias do not have a similar rate of ‘two hit’ structural alterations in PTEN (intragenic mutation, loss of heterozygosity) to GBM in the context of high expression in the developing human is at first puzzling. However, thyroid neoplasias likely have an epigenetic ‘second hit’: decreased transcription, decreased translation and/or differential subcellular compartmentalization between nucleus and cytoplasm might pertain (40). Thus, dysfunctional or haploinsufficient PTEN in the developing thyroid, where normal expression is high, leads to the prominent thyroid manifestations, mostly not malignant, of CS and BRR; somatic genetic alterations and other non-genetic mechanisms of loss-of-function of PTEN lead to thyroid neoplasia.
Gastrointestinal system
PTEN expression was weak in the stomach at days 37 and 41 (Fig. 1A and B, respectively). Weak PTEN expression was also seen in the epithelium and muscle in the small intestine and colon during the 17th week but PTEN expression was strong in the nerve plexus (Fig. 1G–H). A similar pattern was observed by Kremer et al. (20) and Luuko et al. (21) using RNA in situ hybridization in developing mice. Interestingly, the epithelial cells of the small intestine and colon do have relatively high PTEN expression in the adult human but not as intense as the enteric nerves (X.P. Zhou and C. Eng, unpublished results). Intestinal hamartomatous polyps and, rarely, adenomatous polyps could be common in patients with CS but, because they are usually asymptomatic, a large systematic study has not been performed to examine this issue (44). Hamartomatous polyps are prominent in BRR. Very rarely, adenocarcinoma of the large intestine has been reported in CS patients although most do not believe this is a component of PHTS (45,46). Indeed, the risk for colon cancer in a population-based study of CS is estimated at 5%, no different from the general population (44). Similar, but not identical, epithelial changes have been observed in mice: two murine knockout models had hyperplastic polyps and one had colorectal carcinomas (35,37). In another mouse model, gastrointestinal polyps and adenomas have been seen in association with lymphoid tissue (36). Somatic PTEN mutations have been reported in ~20% of microsatellite unstable colon carcinomas (47) although other groups have not found any mutations in colorectal carcinomas (48).
In the 13-week-old fetus, relatively high levels of PTEN protein were noted in the oesophageal epithelium (Fig. 1E) as compared with earlier stages (Fig. 1B). Oesophageal as well as gastric hamartomatous polyps are seen, with unknown frequency, in CS and BRR. However, upper tract carcinomas are not a component of PHTS. Indeed, somatic PTEN mutations have not been observed in cancer of the stomach or oesophagus (49).
The liver showed some PTEN expression at day 41 (Fig. 1B). After 17 weeks, parenchymal liver tissue did not show any PTEN expression although intrahepatic vascular endothelial cells stained strongly (Fig. 1I). The immunostaining pattern in murine hepatic development differs from that in the human. Kremer et al. (20) found strong pten expression in the liver in mice at stage E12.5 (days 47–48 in human development) while Luukko et al. (21) observed weak to moderate pten expression at stage E15 (days 52–56.5 in human development). Interestingly, these expressional differences between mouse and man may explain the discrepancy of findings in the mouse knockout models, human PHTS and sporadic human liver cancers. Adenomatous hyperplasia and tumours of the liver have been reported in mice lacking pten (36,37). In contrast, liver tumours are very rare in CS patients and are not believed to be a component of CS or BRR. Further, only one study reported a frequency of somatic PTEN mutations in only 3% of hepatocellular carcinomas (50).
Pulmonary and cardiovascular system
A weak to moderate PTEN staining intensity was seen in mesenchymal cells of the lung (Fig. 1J) while epithelial cells stained strongly. In contrast, Luukko et al. (21) observed high levels of pten transcripts in epithelial and mesenchymal cells of the mouse. Mutations in PTEN are rather rare in primary tumours of the human lung (12,51) but have been found in up to 25% of brain metastases from lung carcinoma (52). The overall low frequency of PTEN mutations in lung carcinoma, no lung carcinomas in PHTS and the overall lack of prominent pulmonary epithelial developmental defects in PHTS might reflect the importance of the mesenchyme in this regard. The heart was devoid of PTEN staining at day 37 (Fig. 1D) as well as after 17 weeks (data not shown). No cardiac anomalies are associated with PHTS.
Vascular endothelial cells stained strongly for PTEN (Fig. 1I) and served as useful internal controls, as described previously (40,53). Of note, arterio-venous malformations are common findings in patients with BRR, can occur in CS cases and are very prominent in Proteus-like patients (8,29,31,54). Further, a recent study showed that phosphatidylinositol 3-kinase signalling is capable of mediating angiogenesis and expression of vascular endothelial growth factor in endothelial cells (55). PTEN encodes a multifunctional phosphatase capable of dephosphorylating the same sites in membrane phosphatidylinositols phosphorylated by phosphatidylinositol 3'-kinase (PI3K) (56).
Genitourinary system
No PTEN expression was seen in seminiferous tubules containing sustentacular cells and spermatogonial cells while the surrounding basal layer showed strong PTEN expression in a 17-week-old fetus (Fig. 1K). Di Cristofano et al. (35) observed abnormal testicular stromal cells in their mice hemizygously lacking pten exons 4–6. Only one study in humans found PTEN mutations (33%) and loss of heterozygosity (60%) quite frequently but these were found in cultured testicular cancer cell lines (12). In contrast, testicular cancer has not been observed in CS or BRR patients, although cryptorchidism has been noted in BRR (57).
In the developing human kidney, PTEN expression was seen in mesenchymal and epithelial cells of the mesonephros at day 41 (Fig. 1B). In a 17-week-old fetus, glomeruli showed a strong signal while the Bowman capsule and tubuli showed a weak to moderate signal (Fig. 1L). The strong staining intensity of glomeruli correlates well with the strong staining intensity of endothelial cells. Luukko et al. (21) reported a rather weak expression of pten in epithelial glomeruli at stage E15 of murine development while other epithelial and mesenchymal tissue of the kidney stained more strongly. PTEN mutations are found in up to 13% of primary kidney carcinomas (12). Previously not believed to be a component of PHTS, further study in the clinical setting has revealed that clear cell renal cell carcinoma might actually be a minor component of CS (6,7) (C. Eng, unpublished observations). The implied role of PTEN in human kidney development based on PTEN expressional patterns might be reflected in the observation of genitourinary abnormalities, e.g. horseshoe kidney and multiple ureters seen in CS patients (29).
Unfortunately, no tissue was available from developing endometrium or prostate. Mutation analysis and mouse models support an important role of PTEN during tumorigenesis of these tissues, at least in the sporadic setting (58–60).
Lymphatic tissue
The thymus showed an overall moderate to high PTEN expression (Fig. 1M). This observation has also been made in murine development using transcript levels as a measure of expression (20,21). Accordingly, all mouse models show involvement of lymphatic tissues: enlargement of the thymus and splenomegaly (37), tumours of the gastrointestinal epithelium associated with lymphoid tissue, lymphoma/leukaemia of the T-cell type and lymphoma cells in liver, kidney and lung, spleen and thymus (36). PTEN mutations and hemizygous deletions have been reported in 40% of haematological malignancy lines not selected for T-cell defects, and an absence of PTEN protein in 60–70% of these lines was noted (61). In contrast, PHTS patients do not have an increased frequency of haematological malignancies and certainly not of the T-cell variety (29). Immunological studies, however, have revealed impairment of T-cell function in patients with CS (62). Anecdotally, clinicians that care for a large number of PHTS patients might feel that these patients have more autoimmune phenomena than the population-at-large (C. Eng, unpublished observations). These clinical observations, together with the expression pattern during human development, and murine models, might argue for a more formal examination of immune function in individuals with PHTS.
Mucocutaneous system
In the skin (Fig. 1N), a moderate level of PTEN expression was seen around the epidermal ridge while the more superficial layers stained more weakly. The precursors of the infundibulum of the hair follicle, from which trichilemmomas arise, show high levels of PTEN expression (data not shown). In the adult skin, moderate PTEN expression is noted in the basal layer of the epidermis (X.P. Zhou and C. Eng, unpublished results). In the mouse, Luukko et al. (21) observed a more prominent pten transcript expression in the mesenchymal cells beneath the epithelial cells with lower expression. Pten knockout mice showed focal acanthosis (35) but none of the typical changes (trichilemmomas and papillomatosis) frequently seen in patients with CS. In CS, benign hamartomas of the skin, namely, trichilemmomas and papillomatosis, are the sine qua non of the syndrome yet dermatological cancer is not prominent (29); however, it has been observed in some cases (63). This clinical observation might reflect the weak to moderate but sustained PTEN expression during mucocutaneous development where haploinsufficient or dysfunctional PTEN expression during critical periods could lead to these developmental lesions.
Of interest, we observed strong PTEN staining intensity in mesenchymal melanoblasts (Fig. 1N). To date, while somatic intragenic PTEN mutations in malignant melanoma have not been prominent in primary tumours, occurring in up to 10% (12), this high level of PTEN expression in the mesenchymal melanoblasts during early development may explain the pigmentary changes in PHTS. These include characteristically, café-au-lait spots in CS (unusual) and more prominently, the pigmented macules of the glans penis (speckled penis) which help to clinically define BRR.
Conclusions
In this study, we observed mainly high-level PTEN expression during human development in tissues (e.g. skin, thyroid and central nervous system) known to be involved in CS and BRR. We further identified tissues (e.g. peripheral nervous system, autonomomic nervous system, upper GI tract) with high PTEN expression not commonly known to play a role in these syndromes nor in sporadic tumorigenesis in those organs. This knowledge may help to identify roles for PTEN which, as of today, are unknown or even unsuspected.
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MATERIALS AND METHODS |
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Tissue sections
The tissue sections were taken from whole human embryos and fetuses obtained after induced abortions performed in accordance with the French legislation and after allowance of the Ethical Committee (64). Five embryos (26, 32, 37, 41 and 50 days) and two fetuses (13 and 17 weeks) were studied. Tissues were fixed with 4% paraformaldehyde and embedded in paraffin-blocks. Sections (5 µm) were mounted on Superfrost plus slides.
Anti-PTEN antibody specificity
The monoclonal antibody 6H2.1 (J.A. Lees, unpublished results) raised against the last 100 C-terminal amino acids of human PTEN was used in all immunohistochemical analyses. The specificity of this antibody has been demonstrated in two previous studies (40,53). In brief, total protein lysates were obtained from a series of cell lines, for which PTEN status is known. Further, as an additional positive control, wild-type full-length human PTEN cDNA sequence was cloned into the expression vector pcDNA3 and transfected into PTEN null lines. Performing western blot analysis using 6H2.1 revealed that cell lines with endogenously expressing or exogenously introduced PTEN all had a single immunoreactive band at 55 kDa, the molecular weight predicted for PTEN, while the PTEN null lines did not cross-react with 6H2.1.
Immunohistochemistry
Immunohistochemistry was performed as described previously (40,53) with the following modifications. In order to block endogenous peroxidase activity, the sections were incubated with 1% hydrogen peroxide in phosphate-buffered saline for 30 min. After blocking for 30 min in 0.75% horse serum, the sections were incubated with a PTEN monoclonal antibody 6H2.1 (dilution 1:200) overnight at 4°C. Primary antibody binding was localized by using an avidin–biotin–peroxidase kit (Vector Laboratories, Burlingame, CA) according to the manufacturer’s instructions. The staining intensity was classified as absent, weak, moderate or strong.
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ACKNOWLEDGEMENTS |
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We thank Terry Bradley, Dominique Esnault and Laura J. Rush for outstanding technical assistance. This work was supported partially by the American Cancer Society (RPG98-211-01-CCE), US Army Breast Cancer Research Program (DAMD17-98-1-8058) (both to C.E.) and the National Institutes of Health (NCI P30CA16058 to the Ohio State University Comprehensive Cancer Center).
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FOOTNOTES |
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+ To whom correspondence should be addressed at: Human Cancer Genetics Program, Room 690C MRF, Ohio State University, 420 W 12th Avenue, Columbus, OH 43210, USA. Tel: +1 614 688 4508; Fax: +1 614 688 3582; Email: eng-1@medctr.osu.edu
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REFERENCES |
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1 Li, J., Yen, C., Liaw, D., Podsypanina, K., Bose, S., Wang, S.I., Puc, J., Miliaresis, C., Rodgers, L., McCombie, R. et al. (1997) PTEN, a putative protein tyrosine phosphatase gene mutated in human brain, breast, and prostate cancer [see comments]. Science, 275, 1943–1947.
2 Steck, P.A., Pershouse, M.A., Jasser, S.A., Yung, W.K., Lin, H., Ligon, A.H., Langford, L.A., Baumgard, M.L., Hattier, T., Davis, T. et al. (1997) Identification of a candidate tumour suppressor gene, MMAC1, at chromosome 10q23.3 that is mutated in multiple advanced cancers. Nature Genet., 15, 356–362.[Web of Science][Medline]
3 Li, D.M. and Sun, H. (1997) TEP1, encoded by a candidate tumor suppressor locus, is a novel protein tyrosine phosphatase regulated by transforming growth factor beta. Cancer Res., 57, 2124–2129.
4 Liaw, D., Marsh, D.J., Li, J., Dahia, P.L., Wang, S.I., Zheng, Z., Bose, S., Call, K.M., Tsou, H.C., Peacocke, M. et al. (1997) Germline mutations of the PTEN gene in Cowden disease, an inherited breast and thyroid cancer syndrome. Nature Genet., 16, 64–67.[Web of Science][Medline]
5 Marsh, D.J., Dahia, P.L., Zheng, Z., Liaw, D., Parsons, R., Gorlin, R.J. and Eng, C. (1997) Germline mutations in PTEN are present in Bannayan-Zonana syndrome. Nature Genet., 16, 333–334.[Web of Science][Medline]
6 Marsh, D.J., Coulon, V., Lunetta, K.L., Rocca-Serra, P., Dahia, P.L., Zheng, Z., Liaw, D., Caron, S., Duboue, B., Lin, A.Y. et al. (1998) Mutation spectrum and genotype–phenotype analyses in Cowden disease and Bannayan–Zonana syndrome, two hamartoma syndromes with germline PTEN mutation. Hum. Mol. Genet., 7, 507–515.
7 Marsh, D.J., Kum, J.B., Lunetta, K.L., Bennett, M.J., Gorlin, R.J., Ahmed, S.F., Bodurtha, J., Crowe, C., Curtis, M.A., Dasouki, M. et al. (1999) PTEN mutation spectrum and genotype-phenotype correlations in Bannayan–Riley–Ruvalcaba syndrome suggest a single entity with Cowden syndrome. Hum. Mol. Genet., 8, 1461–1472.
8 Zhou, X.P., Marsh, D.J., Hampel, H., Mulliken, J.B., Gimm, O. and Eng, C. (2000) Germline and germline mosaic PTEN mutations associated with Proteus-like syndrome of hemihypertrophy, lower limb asymmetry, arterio-venous malformations and lipomatosis. Hum. Mol. Genet., 9, 765–768.
9 Wang, S.I., Puc, J., Li, J., Bruce, J.N., Cairns, P., Sidransky, D. and Parsons, R. (1997) Somatic mutations of PTEN in glioblastoma multiforme. Cancer Res., 57, 4183–4186.
10 Rasheed, B.K., Stenzel, T.T., McLendon, R.E., Parsons, R., Friedman, A.H., Friedman, H.S., Bigner, D.D. and Bigner, S.H. (1997) PTEN gene mutations are seen in high-grade but not in low-grade gliomas. Cancer Res., 57, 4187–4190.
11 Risinger, J.I., Hayes, A.K., Berchuck, A. and Barrett, J.C. (1997) PTEN/MMAC1 mutations in endometrial cancers. Cancer Res., 57, 4736–4738.
12 Teng, D.H., Hu, R., Lin, H., Davis, T., Iliev, D., Frye, C., Swedlund, B., Hansen, K.L., Vinson, V.L., Gumpper, K.L. et al. (1997) MMAC1/PTEN mutations in primary tumor specimens and tumor cell lines. Cancer Res., 57, 5221–5225.
13 Nelen, M.R., Padberg, G.W., Peeters, E.A., Lin, A.Y., van den Helm, B., Frants, R.R., Coulon, V., Goldstein, A.M., van Reen, M.M., Easton, D.F. et al. (1996) Localization of the gene for Cowden disease to chromosome 10q22–23. Nature Genet., 13, 114–116.[Web of Science][Medline]
14 Eng, C. (1997) Cowden Syndrome. J. Genet. Counsel., 6, 181–192.
15 Furnari, F.B., Huang, H.J. and Cavenee, W.K. (1998) The phosphoinositol phosphatase activity of PTEN mediates a serum-sensitive G1 growth arrest in glioma cells. Cancer Res., 58, 5002–5008.
16 Li, D.M. and Sun, H. (1998) PTEN/MMAC1/TEP1 suppresses the tumorigenicity and induces G1 cell cycle arrest in human glioblastoma cells. Proc. Natl Acad. Sci. USA, 95, 15406–15411.
17 Weng, L.P., Smith, W.M., Dahia, P.L., Ziebold, U., Gil, E., Lees, J.A. and Eng, C. (1999) PTEN suppresses breast cancer cell growth by phosphatase activity-dependent G1 arrest followed by cell death. Cancer Res., 59, 5808–5814.
18 Gu, J., Tamura, M. and Yamada, K.M. (1998) Tumor suppressor PTEN inhibits integrin- and growth factor-mediated mitogen-activated protein (MAP) kinase signaling pathways. J. Cell Biol., 143, 1375–1383.
19 Tamura, M., Gu, J., Matsumoto, K., Aota, S., Parsons, R. and Yamada, K.M. (1998) Inhibition of cell migration, spreading, and focal adhesions by tumor suppressor PTEN. Science, 280, 1614–1617.
20 Kremer, H., Nelen, M., Schepens, J., Hendrik, W. and Padberg, G. (1999) PTEN transcription in mouse development. Am. J. Hum. Genet., 65 (Suppl.), A134.
21 Luukko, K., Ylikorkala, A., Tiainen, M. and Makela, T.P. (1999) Expression of LKB1 and PTEN tumor suppressor genes during mouse embryonic development. Mech. Dev., 83, 187–190.[Web of Science][Medline]
22 Dahia, P.L., FitzGerald, M.G., Zhang, X., Marsh, D.J., Zheng, Z., Pietsch, T., von Deimling, A., Haluska, F.G., Haber, D.A. and Eng, C. (1998) A highly conserved processed PTEN pseudogene is located on chromosome band 9p21. Oncogene 16, 2403–2406.[Web of Science][Medline]
23 Forgacs, E., Biesterveld, E.J., Sekido, Y., Fong, K., Muneer, S., Wistuba, II, Milchgrub, S., Brezinschek, R., Virmani, A., Gazdar, A.F. et al. (1998) Mutation analysis of the PTEN/MMAC1 gene in lung cancer. Oncogene, 17, 1557–1565.[Web of Science][Medline]
24 Whang, Y.E., Wu, X. and Sawyers, C.L. (1998) Identification of a pseudogene that can masquerade as a mutant allele of the PTEN/MMAC1 tumor suppressor gene. J. Natl Cancer Inst., 90, 859–861.
25 Fujii, G.H., Morimoto, A.M., Berson, A.E. and Bolen, J.B. (1999) Transcriptional analysis of the PTEN/MMAC1 pseudogene, psiPTEN. Oncogene, 18, 1765–1769.[Web of Science][Medline]
26 Liu, J. and Kagan, J. (1999) Method to distinguish between the MMAC1/PTEN gene and its pseudogene in RT–PCR analysis of point mutations. Biotechniques, 26, 19–22, 24.[Web of Science][Medline]
27 Fougerousse, F., Bullen, P., Herasse, M., Lindsay, S., Richard, I., Wilson, D., Suel, L., Durand, M., Robson, S., Abitbol, M. et al. (2000) Human–mouse differences in the embryonic expression patterns of developmental control genes and disease genes. Hum. Mol. Genet., 9, 165–173.
28 Duerr, E.M., Rollbrocker, B., Hayashi, Y., Peters, N., Meyer-Puttlitz, B., Louis, D.N., Schramm, J., Wiestler, O.D., Parsons, R., Eng, C. et al. (1998) PTEN mutations in gliomas and glioneuronal tumors. Oncogene, 16, 2259–2264.[Web of Science][Medline]
29 Eng, C. (1998) Genetics of Cowden syndrome: through the looking glass of oncology. Int. J. Oncol., 12, 701–710.[Web of Science][Medline]
30 Saul, R.A., Stevenson, R.E. and Bley, R. (1982) Mental retardation in the Bannayan syndrome. Pediatrics, 69, 642–644.
31 Fargnoli, M.C., Orlow, S.J., Semel-Concepcion, J. and Bolognia, J.L. (1996) Clinicopathologic findings in the Bannayan–Riley–Ruvalcaba syndrome. Arch. Dermatol., 132, 1214–1218.
32 Liu, W., James, C.D., Frederick, L., Alderete, B.E. and Jenkins, R.B. (1997) PTEN/MMAC1 mutations and EGFR amplification in glioblastomas. Cancer Res., 57, 5254–5257.
33 Fults, D., Pedone, C.A., Thompson, G.E., Uchiyama, C.M., Gumpper, K.L., Iliev, D., Vinson, V.L., Tavtigian, S.V. and Perry III, W.L. (1998) Microsatellite deletion mapping on chromosome 10q and mutation analysis of MMAC1, FAS, and MXI1 in human glioblastoma multiforme. Int. J. Oncol., 12, 905–910.[Web of Science][Medline]
34 Zhou, X.P., Li, Y.J., Hoang-Xuan, K., Laurent-Puig, P., Mokhtari, K., Longy, M., Sanson, M., Delattre, J.Y., Thomas, G. and Hamelin, R. (1999) Mutational analysis of the PTEN gene in gliomas: molecular and pathological correlations. Int. J. Cancer, 84, 150–154.[Web of Science][Medline]
35 Di Cristofano, A., Pesce, B., Cordon-Cardo, C. and Pandolfi, P.P. (1998) Pten is essential for embryonic development and tumour suppression. Nature Genet., 19, 348–355.[Web of Science][Medline]
36 Suzuki, A., de la Pompa, J.L., Stambolic, V., Elia, A.J., Sasaki, T., del Barco Barrantes, I., Ho, A., Wakeham, A., Itie, A., Khoo, W. et al. (1998) High cancer susceptibility and embryonic lethality associated with mutation of the PTEN tumor suppressor gene in mice. Curr. Biol., 8, 1169–1178.[Web of Science][Medline]
37 Podsypanina, K., Ellenson, L.H., Nemes, A., Gu, J., Tamura, M., Yamada, K.M., Cordon-Cardo, C., Catoretti, G., Fisher, P.E. and Parsons, R. (1999) Mutation of Pten/Mmac1 in mice causes neoplasia in multiple organ systems. Proc. Natl Acad. Sci. USA, 96, 1563–1568.
38 Eng, C. and Parsons, R. (1998) Cowden syndrome. In Vogelstein, B. and Kinzler, K.W. (eds), The Genetic Basis of Human Cancer. McGraw–Hill, New York, NY, pp. 519–526.
39 Lashner, B.A., Riddell, R.H. and Winans, C.S. (1986) Ganglio- neuromatosis of the colon and extensive glycogenic acanthosis in Cowden’s disease. Dig. Dis. Sci., 31, 213–216.[Web of Science][Medline]
40 Gimm, O., Perren, A., Weng, L.P., Marsh, D.J., Yeh, J.J., Ziebold, U., Gil, E., Hinze, R., Delbridge, L., Lees, J.A. et al. (2000) Differential nuclear and cytoplasmic expression of PTEN in normal thyroid tissue, and benign and malignant epithelial thyroid tumors. Am. J. Pathol., 156, 1693–1700.
41 Dahia, P.L., Marsh, D.J., Zheng, Z., Zedenius, J., Komminoth, P., Frisk, T., Wallin, G., Parsons, R., Longy, M., Larsson, C. et al. (1997) Somatic deletions and mutations in the Cowden disease gene, PTEN, in sporadic thyroid tumors. Cancer Res., 57, 4710–4713.
42 Halachmi, N., Halachmi, S., Evron, E., Cairns, P., Okami, K., Saji, M., Westra, W.H., Zeiger, M.A., Jen, J. and Sidransky, D. (1998) Somatic mutations of the PTEN tumor suppressor gene in sporadic follicular thyroid tumors. Genes Chromosomes Cancer, 23, 239–243.[Web of Science][Medline]
43 Marsh, D.J., Zheng, Z., Zedenius, J., Kremer, H., Padberg, G.W., Larsson, C., Longy, M. and Eng, C. (1997) Differential loss of heterozygosity in the region of the Cowden locus within 10q22–23 in follicular thyroid adenomas and carcinomas. Cancer Res., 57, 500–503.
44 Starink, T.M. (1984) Cowden’s disease: analysis of fourteen new cases. J. Am. Acad. Dermatol., 11, 1127–1141.[Web of Science][Medline]
45 Haggitt, R.C. and Reid, B.J. (1986) Hereditary gastrointestinal polyposis syndromes. Am. J. Surg. Pathol., 10, 871–887.[Web of Science][Medline]
46 Hover, A.R., Cawthern, T. and McDanial, W. (1986) Cowden disease. A hereditary polyposis syndrome diagnosable by mucocutaneous inspection. J. Clin. Gastroenterol., 8, 576–579.[Web of Science][Medline]
47 Guanti, G., Resta, N., Simone, C., Cariola, F., Demma, I., Fiorente, P. and Gentile, M. (2000) Involvement of PTEN mutations in the genetic pathways of colorectal cancerogenesis. Hum. Mol. Genet., 9, 283–287.
48 Wang, Z.J., Taylor, F., Churchman, M., Norbury, G. and Tomlinson, I. (1998) Genetic pathways of colorectal carcinogenesis rarely involve the PTEN and LKB1 genes outside the inherited hamartoma syndromes. Am. J. Pathol., 153, 363–366.
49 Chang, J.G., Chen, Y.J., Perng, L.I., Wang, N.M., Kao, M.C., Yang, T.Y., Chang, C.P. and Tsai, C.H. (1999) Mutation analysis of the PTEN/MMAC1 gene in cancers of the digestive tract. Eur. J. Cancer, 35, 647–651.
50 Yao, Y.J., Ping, X.L., Zhang, H., Chen, F.F., Lee, P.K., Ahsan, H., Chen, C.J., Lee, P.H., Peacocke, M., Santella, R.M. et al. (1999) PTEN/MMAC1 mutations in hepatocellular carcinomas. Oncogene, 18, 3181–3185.[Web of Science][Medline]
51 Sakurada, A., Suzuki, A., Sato, M., Yamakawa, H., Orikasa, K., Uyeno, S., Ono, T., Ohuchi, N., Fujimura, S. and Horii, A. (1997) Infrequent genetic alterations of the PTEN/MMAC1 gene in Japanese patients with primary cancers of the breast, lung, pancreas, kidney, and ovary. Jpn J. Cancer Res., 88, 1025–1028.[Web of Science][Medline]
52 Hahn, M., Wieland, I., Koufaki, O.N., Gorgens, H., Sobottka, S.B., Schackert, G. and Schackert, H.K. (1999) Genetic alterations of the tumor suppressor gene PTEN/MMAC1 in human brain metastases. Clin. Cancer Res., 5, 2431–2437.
53 Perren, A., Weng, L.P., Boag, A.H., Ziebold, U., Thakore, K., Dahia, P.L., Komminoth, P., Lees, J.A., Mulligan, L.M., Mutter, G.L. et al. (1999) Immunohistochemical evidence of loss of PTEN expression in primary ductal adenocarcinomas of the breast. Am. J. Pathol., 155, 1253–1260.
54 Longy, M., Coulon, V., Duboue, B., David, A., Larregue, M., Eng, C., Amati, P., Kraimps, J.L., Bottani, A., Lacombe, D. et al. (1998) Mutations of PTEN in patients with Bannayan–Riley–Ruvalcaba phenotype. J. Med. Genet., 35, 886–889.
55 Jiang, B.H., Zheng, J.Z., Aoki, M. and Vogt, P.K. (2000) Phosphatidylinositol 3-kinase signaling mediates angiogenesis and expression of vascular endothelial growth factor in endothelial cells. Proc. Natl Acad. Sci. USA, 97, 1749–1753.
56 Stambolic, V., Suzuki, A., de la Pompa, J.L., Brothers, G.M., Mirtsos, C., Sasaki, T., Ruland, J., Penninger, J.M., Siderovski, D.P. and Mak, T.W. (1998) Negative regulation of PKB/Akt-dependent cell survival by the tumor suppressor PTEN. Cell, 95, 29–39.[Web of Science][Medline]
57 Desai, D.C., Murday, V., Phillips, R.K., Neale, K.F., Milla, P. and Hodgson, S.V. (1998) A survey of phenotypic features in juvenile polyposis. J. Med. Genet., 35, 476–481.
58 Cairns, P., Okami, K., Halachmi, S., Halachmi, N., Esteller, M., Herman, J.G., Jen, J., Isaacs, W.B., Bova, G.S. and Sidransky, D. (1997) Frequent inactivation of PTEN/MMAC1 in primary prostate cancer. Cancer Res., 57, 4997–5000.
59 Tashiro, H., Blazes, M.S., Wu, R., Cho, K.R., Bose, S., Wang, S.I., Li, J., Parsons, R. and Ellenson, L.H. (1997) Mutations in PTEN are frequent in endometrial carcinoma but rare in other common gynecological malignancies. Cancer Res., 57, 3935–3940.
60 Yoshinaga, K., Sasano, H., Furukawa, T., Yamakawa, H., Yuki, M., Sato, S., Yajima, A. and Horii, A. (1998) The PTEN, BAX, and IGFIIR genes are mutated in endometrial atypical hyperplasia. Jpn J. Cancer Res., 89, 985–990.[Web of Science][Medline]
61 Dahia, P.L., Aguiar, R.C., Alberta, J., Kum, J.B., Caron, S., Sill, H., Marsh, D.J., Ritz, J., Freedman, A., Stiles, C. et al. (1999) PTEN is inversely correlated with the cell survival factor Akt/PKB and is inactivated via multiple mechanismsin haematological malignancies. Hum. Mol. Genet., 8, 185–193.
62 Halevy, S., Sandbank, M., Pick, A.I. and Feuerman, E.J. (1985) Cowden’s disease in three siblings: electron-microscope and immunological studies. Acta Derm. Venereol., 65, 126–131.[Web of Science][Medline]
63 O’Hare, A.M., Cooper, P.H. and Parlette III, H.L. (1997) Trichilemmomal carcinoma in a patient with Cowden’s disease (multiple hamartoma syndrome). J. Am. Acad. Dermatol., 36, 1021–1023.[Web of Science][Medline]
64 Attie-Bitach, T., Abitbol, M., Gerard, M., Delezoide, A.L., Auge, J., Pelet, A., Amiel, J., Pachnis, V., Munnich, A., Lyonnet, S. et al. (1998) Expression of the RET proto-oncogene in human embryos. Am. J. Med. Genet., 80, 481–486.[Web of Science][Medline]
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