Human Molecular Genetics Advance Access originally published online on July 6, 2005
Human Molecular Genetics 2005 14(16):2435-2442; doi:10.1093/hmg/ddi245
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Differential nonsense mediated decay of mutated mRNAs in mismatch repair deficient colorectal cancers
1INSERM U434, 27 rue Juliette Dodu, Hôpital Saint-Louis, 75010 Paris, France and 2INSERM EMI 0210, 149 rue de Sèvres, Hôpital Necker, 75015 Paris, France
* To whom correspondence should be addressed. Tel: +33 153725120; Fax: +33 153725192; Email: alex.duval{at}cephb.fr
Received May 10, 2005; Revised June 23, 2005; Accepted July 1, 2005
 |
ABSTRACT |
|---|
 TOP ABSTRACT INTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
The nonsense-mediated decay (NMD) system normally targets mRNAs with premature termination codons (PTCs) for rapid degradation. We investigated for a putative role of NMD in cancers with microsatellite instability (MSI-H cancers), because numerous mutant mRNAs containing PTC are generated in these tumors as a consequence of their mismatch repair deficiency. Using a quantitative RT–PCR approach in a large series of colorectal cancer cell lines, we demonstrate a significantly increased rate of degradation of mutant mRNAs containing a PTC compared with wild-type. A specific siRNA strategy was used to inhibit RENT-1 and/or RENT-2 activity, two major genes in the NMD system. This allowed us to show that increased degradation of PTC-containing mRNAs in MSI-H tumors was partly dependent upon NMD activity. The efficiency of NMD for the degradation of mutant mRNAs from target genes was highly variable in these cancers. NMD degraded some of them (TGFßRII, MSH3, GRK4), although allowing the persistent expression of others (BAX, TCF-4). This is of particular interest within the context of a proposed conservation of biological activity for the corresponding mutated proteins. We thus propose that NMD might play an important role in the selection of target gene mutations with a functional role in MSI-H carcinogenesis.
|
INTRODUCTION |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
A subset of cancers is characterized by mismatch repair (MMR) deficiency arising from the inactivation of mismatch repair genes (1
,2,3). As a consequence, these tumors exhibit a so-called mutator phenotype, which is characterized by global instability affecting microsatellite repeat sequences. These cancers are inherited when they occur within the context of the hereditary non-polyposis colorectal cancer (HNPCC) syndrome (4,5,6,7) or can occur sporadically in 10–15% of colorectal, gastric and endometrial carcinomas (8). It has been clearly shown that simple inactivation of a MMR gene is not by itself a transforming event and therefore additional genetic changes are believed necessary for MSI-H cells to become malignant. Most are 1 or 2 bp insertion or deletion mutations found within genes containing coding repeat sequences that are particularly prone to alterations in MSI-H cancers (9). These mutations result in frameshifts leading to the synthesis of mutant mRNAs containing premature termination codons (PTCs) and encoding for truncated proteins. Even if most of them are thought to be loss of function events affecting putative tumor suppressor genes with a putative role in these tumors, there is a lack of functional studies relying on the biological activity of the corresponding mutated proteins.
The nonsense-mediated decay (NMD) system targets mRNAs with PTC for rapid degradation. It is mediated through the assembly of protein complexes derived from genes such as those of the UPF family and including RENT-1/UPF-1, RENT-2/UPF-2, UPF-3A and UPF-3B (10). RENT-1 has been shown to play a crucial role in NMD function, whereas the function of other components of this system is thought to be more redundant. The discrimination of PTC-containing mRNAs in mammalian cells depends on their position within the molecule. Schematically, termination codons located more than 55 nucleotides upstream of the most 3' exon–exon junction are interpreted as premature by the NMD system, reflecting the importance of splicing in mammalian NMD. PTCs localized downstream of this site are therefore not recognized by the NMD system (11). NMD has been shown to play a beneficial role in several pathologies by favoring the elimination of mRNAs that encode for potentially dominant negative proteins (12). In other clinical contexts including some cancers, inhibition of NMD may prevent the degradation of transcripts containing PTC that encode for fully or partly functional truncated proteins (12).
Little is known about the activity of NMD in MSI-H tumors, even though it is expected to play an important role by halting the expression of many genes that are targeted by the mutator pathway in these cancers. Inhibition of mRNA decay by non-specific drugs such as emitine has allowed the identification of two mutated target genes whose mRNAs were highly degraded by this system (13). Nevertheless, this drug also induces a stress response that results in the upregulation of many transcripts. We therefore developed an alternate approach to investigate NMD function in MSI-H colorectal carcinogenesis. NMD activity was significant in this cancer subgroup and was associated with differential rates of decay of frameshift-mutated mRNAs. Our findings suggest that NMD activity influences the assortment of mutational events that occur during MSI-H carcinogenesis.
|
RESULTS |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
Overall decay of mutated mRNAs in colorectal cancer cells
Target gene expression values (
Ct) for BAX, CBF2, IGFIIR, MSH3, MSH6, RAD50, TCF-4, BLM, RECQL, ATR, RBBP8, TLOC1, TFDP2, CASP5, GRK4, GRB14 and TGFßRII mRNAs were determined in MSI-H and non-MSI cell lines. None of the selected target genes showed coding repeat mutations in the non-MSI cell lines taken as negative controls, whereas all were previously shown (14,15) to be heterozygous or homozygous mutants in MSI-H cell lines (1 bp deletion or insertion). To examine the putative effect of these frameshift alterations on the overall expression of the corresponding mutant mRNAs, Ct values were normalized and classified into three groups according to the mutational status of each target gene in these cancers (wild-type, heterozygous, homozygous). A highly significant negative effect for the presence of these alterations was observed with the global level of expression of the corresponding mRNAs (Stata nptrend, P<1x10–7). This effect was still highly significant when only the data relating to mRNA expression in the nine MSI-H cancer cell lines was considered (Stata nptrend, P<1.5x10–4).
Differential impact of frameshift mutations on the expression of mutant mRNAs in MSI-H colorectal cancer cells
The Ct values relative to each target gene are indicated in Figure 1 by black triangles, gray squares and white lozenges for homozygous mutations, heterozygous mutations and wild-type genes, respectively. The presence of frameshift mutations was shown to affect mRNA expression levels for the corresponding genes to varying degrees. Although fluctuating expression levels were observed for each gene depending on the cell line and the low frequency of some mutational events in these tumors, a correlation was seen for some target genes (indicated by an arrow e.g. CBF2, MSH3, GRB14; Stata nptrend: P=0,02, P=0,008 and P=0,003, respectively) (Fig. 1). For others, there was only a tendency for association with degradation (e.g. BAX, IGFIIR, MSH6, RAD50, BLM, RECQL, ATR, TLOC1, GRK4, TGFßRII). In contrast, no degradation and even increased expression of TCF-4, RBBP8, TFDP2 and CASP-5 was observed. Among these four latter genes, TCF-4 was the only one whose frameshift mutation leads to a PTC localized downstream of the last intron/exon junction, as indicated in Table 1. These results suggest differential effects of frameshift mutation on the degradation of mRNAs in MSI-H colorectal cancer cell lines.
|
, heterozygous 
, homozygous 
). They are inversely correlated to the relative expression values of each gene by the formula: E=2–
|
Some examples of target gene expression values (
Ct) obtained in the cell lines (including MSI-H and non-MSI samples taken as negative controls) are presented in Figure 2.
|
, heterozygous 
, homozygous 
). MSI-H cell lines are indicated by a black triangle. A trend or significant decay of mutant mRNAs was observed for TGFßRII, BAX and MSH3. TCF-4 mutant mRNA appeared resistant to decay in MSI-H tumors, possibly because the PTC is localized to the last exon of this gene.Re-expression of frameshift mutant mRNAs achieved by RENT-1 silencing in MSI-H colorectal cancer cells
Using a siRNA strategy, RENT-1 expression was repressed by
70% in HCT116, LS174T, Co115, SW48 and LoVo MSI-H cell lines. Target mRNA expression values were measured in cells transfected with either the RENT-1 siRNA or the CVII siRNA control, and the percentages of activation (p) were calculated by the formula (p)=2–Ctx100, where Ct corresponds to the difference between Ct obtained in cells transfected with RENT-1 and CVII siRNAs. Using p as an index, a highly significant effect for the re-expression of mutated mRNAs was specifically observed in RENT-1 siRNA-transfected MSI-H cells (Kruskal–Wallis equality of populations rank test; P=5·10–4), whereas the expression of wild-type mRNA was unaffected (Fig. 3). RENT-1 inhibition induced a stronger re-expression of genes in cell lines harboring a mutation on both alleles compared with those with only one mutant allele (Fig. 3).
|
Differential decay of mutant mRNAs containing PTC in MSI-H cancer cells
The overall impact of RENT-1 silencing on the re-expression of heterozygously mutated target genes was generally quite difficult to detect (Fig. 3). The functional impact of RENT-1 silencing on the mRNA re-expression of homozygous mutants appeared inconsistent, however, as illustrated by the enhanced re-expression of TGFßRII, MSH3 and GRK4 (P<0,05, Student's t-test) when compared with that of BAX and TCF-4 which remained unchanged (Fig. 3). These argue for a differential decay of mutant mRNAs containing a PTC in MSI-H cells. If it can be speculated that the site of PTC mutation within the TCF4 transcript (final exon) renders this mRNA unrecognizable to the NMD system, the reason why BAX expression is insensitive to RENT-1 inhibition remains to be determined.
RENT-1 and RENT-2 have an additive effect for frameshift mutation-derived mRNA decay in MSI-H cancer cells
By inhibiting either RENT-1 and/or RENT-2 mRNA expression at comparable rates (70%) in HCT116 cells, NMD activity was found to depend mainly on RENT-1 activity. This highlights the crucial role of this latter protein in NMD system, as already reported. An additive functional effect of these two factors on the decay of homozygously mutated mRNAs containing PTC (TGFßRII, MSH3, GRK4) was, however, observed (Fig. 4).
|
|
DISCUSSION |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
Numerous genes containing coding repeat sequences have so far been reported as targets in the mutator pathway of MMR-deficient cancers (9
). As a consequence, numerous frameshift mutation-derived mRNAs containing PTCs are generated in these tumors. In most cases, these alterations are of unknown functional consequences. Because the expected outcome of frameshift alterations is usually loss of function, most of these mutations have been reported in genes with a putative tumor suppressor function (e.g. in TGFßRII, BAX, IGFIIR, MSH3, MSH6, RAD50 and others). However, in some cases, other functional consequences have been proposed for the presence of these alterations. It has been suggested, for instance, that some of these mutations might have a dominant negative effect (16) or that others could be activating, gain of function mutations (17). As a system that could interfere with the transcriptional regulation of mutated target genes in MSI-H cancers, NMD has thus been proposed to play a role in MSI-H carcinogenesis (13). By analyzing mRNA expression of several target genes containing repeats in which mutations had previously been reported in a panel of MSI-H and non-MSI colorectal cell lines, we found strong evidence for a significant degradation process of frameshift mutation-derived mRNAs in MSI-H cancers. Silencing of RENT-1 expression was then performed on five MSI-H cell lines and allowed us to show that this degradative process was partly dependent on NMD activity (Fig. 3). By RNA silencing of either RENT-1, RENT-2 or both these important NMD factors in the HCT116 cell line, we obtained evidence that frameshift mutation-derived mRNA decay was mainly dependent on RENT-1 activity, with RENT-2 playing a minor but additive role in the process (Fig. 4). Taken together, our data show that NMD is highly involved in target gene mRNA expression levels in MSI-H tumors.
Interestingly, the decay of mutant mRNAs containing PTCs in MSI-H colorectal cancer cell lines differed according to the target gene. Furthermore, variable re-expression rates of these mutant mRNAs were observed following silencing of RENT-1 in these tumors. The fact that we found evidence for differential decay of mutant mRNAs containing PTC in MSI-H cancers is not so surprising. Many transcripts containing PTCs have already been reported not to obey this prediction in normal cells, indicating an incomplete understanding of NMD (12). We found that TGFßRII, MSH3 and GRK4 mutant mRNAs were sensitive to mRNA decay, whereas others such as BAX or TCF-4 were not. TGFßRII was the first reported target gene in MSI-H colorectal carcinoma (18). It is mutated at high frequencies in these cancers, and functional studies demonstrate that these frameshift mutations lead to a loss of TGFßRII tumor suppressor function. The frequent MSH3 loss of function frameshift mutation (19), as a second hit affecting the MMR pathway during tumoral progression, has been proposed to play an important role by increasing the overall instability phenomenon characterizing these tumors (14). GRK4 has previously been reported as frequently mutated in MSI-H colorectal primary tumors (20). Although functional studies are lacking, mutations affecting this G protein-linked receptor kinase are thought to activate multiple intracellular signaling pathways. We observed efficient decay of these three potential tumor suppressor gene mutant mRNAs by NMD in MSI-H cell lines. Conversely, NMD did not lead to efficient degradation of the pro-apoptotic BAX mutated mRNA whose alteration is frequent in MSI-H colorectal cancers and has been shown to confer selective advantage during tumor clonal evolution (21). It was also unable to degrade the frameshift mutation-derived TCF-4 mRNA, as expected, because in this latter case, the PTC of this gene is localized within its last exon. Of interest, mutated TCF-4 is suspected to be oncogenic in MSI-H cancers by enhancing Wnt/Wingless signaling, because the TCF-4 frameshift mutation is believed to enhance the transactivation properties of the protein via a complex mechanism that favors the synthesis of isoforms lacking the ability to bind CtBP, a transcriptional repressor of the TCF/LEF family (17). We have found this protein to be highly expressed in homozygously mutated MSI-H colorectal cancer cell lines (Dartigues et al., manuscript in preparation).
On the basis of analysis of the expression of a series of 17 target genes for instability, these data argue, thus, for a differential decay of mutant mRNA in MSI-H cancers. This is of particular interest within the context of a proposed conservation of biological activity for the corresponding mutated proteins. It can be assumed indeed that among the numerous frameshift mutational events that occur during MSI-H tumoral progression, a number of them would lead to the complete inactivation of the corresponding mutated proteins, while others would allow the persistence of a normal or abnormal residual activity of these mutants. A retained activity of the mutated proteins is particularly expected for target genes containing repeats localized downstream of important functional domains. This has been already proposed for RIZ (22) and AXIN2 (16), e.g. as shown in Figure 5, differential decay of mRNA mutants containing PTC would thus be oncogenic either by contributing to the degradation of some mutant mRNA encoding for proteins that have conserved a residual tumor suppressor function or by allowing the expression of others harboring dominant negative or gain of function mutations. In that context, the relative insensitivity of BAX mutated mRNA to NMD is here of unclear functional significance. It may be related to the putative residual apoptotic function of the corresponding protein. Finally, NMD failure to degrade mutated mRNAs containing PTC downstream of the last intron/exon junction is expected to allow the expression of a number of mutated proteins with unknown residual functions, among which those with an oncogenic role would be selected for in these tumors, as TCF-4 and probably others.
|
Cancers showing microsatellite instability are frequent neoplasms characterized by distinct biological and clinical properties. We show here for the first time a specific involvement of the NMD pathway in MSI-H carcinogenesis that was associated with important modification of target gene expression in these tumors. In the context of MMR deficiency, it therefore appears to be not only a physiological process involved in mRNA maintenance as in normal cells, but rather a general process whose activity leads to different decay rates of mutated mRNAs harboring PTC in these cancers. According to these findings, NMD is expected to generate profound modification of the MSI-H tumoral transcriptome with an additive oncogenic effect. Its specific in vivo inhibition by drugs, similar to that used here, could be of therapeutic interest for the specific treatment of these tumors. Such an approach needs to be performed on MMR-deficient animal models of MSI-H tumors.
|
MATERIAL AND METHODS |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
Cell lines and cultures
Eighteen colorectal cell lines (ALA, Co115, Colo320, FET, FRI, HCT116, HCT15, HT29, Isreco1, LoVo, LS1034, LS174T, LS513, RKO, SW48, TC7, TC71, V9P) of which nine were MSI-H (Co115, HCT116, HCT15, LoVo, LS174T, RKO, TC7, TC71) had previously been screened for frameshift mutations (14
,15) in 17 target genes containing coding microsatellite sequences (BAX, CBF2, IGFIIR, MSH3, MSH6, RAD50, TCF-4, BLM, RECQL, ATR, RBBP8, TLOC1, TFDP2, CASP5, GRK4, GRB14, TGFßRII) (Table 1). A table describing the mutational status of the target genes in the MSI cell lines is proposed as Supplementary Material, Table S2. All cell lines were maintained in DMEM (Life Technologies) containing 10% FCS (Invitrogen).
Quantitative RT–PCR analysis of target mRNAs in colorectal cancer cell lines
Total RNA was extracted from each cell line using the RNEasy extraction kit (Qiagen), and cDNA was synthesized using the high capacity cDNA archive Kit (Applied Biosystems). For quantitative RT–PCR experiments, expression values were obtained from the Ct number at which the increase in signal associated with exponential amplification of PCR products starts to be detected using the Applied SDS Biosystems analysis software according to the manufacturer's instruction. Quantitation of the 18S ubiquitous RNA was used as the endogeneous reference. Results were expressed as N-fold difference in target gene expression relative to 18S expression (Ct), where Ct was determined in each case by subtracting the average Ct value of the target gene from the average Ct value of the 18S gene. Ct is inversely correlated to the relative expression values by the formula:
 |
Transient transfection assays of cell lines using RENT-1 and RENT-2 siRNA
HCT116, LS174T, Co115, SW48 and LoVo MSI-H colorectal cell lines were maintained in DMEM (Life Technologies) containing 10% FCS (Invitrogen). They were transiently transfected in 35 mm dishes in the presence of 100 nM of siRNA duplexes directed against RENT-1, RENT-2 or of non-specific siRNA duplexes (CVII) (Dharmacon) using the lipofectamine 2000 reagent (Invitrogen) and according to manufacturer's instructions. About 50 nM of each RENT-1 and RENT-2 siRNA were used in the case of mixed transfection experiments. An siRNA directed against GAPDH (Dharmacon) was used as transfection control. Cells were collected for total RNA extraction 72 h post-transfection. Each transfection experiment was performed twice and in triplicate. Medium E-values (relative gene expression) were calculated as reported earlier in cells transfected with either RENT or CVII siRNA.
Statistical analyses
All statistical analyses were performed using the STATA 8 package (Stata Corporation, 4905 Lakeway Drive, College Station, TX 77845, USA).
|
SUPPLEMENTARY MATERIAL |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
Supplementary Material is available at HMG Online.
|
ACKNOWLEDGEMENTS |
|---|
We thank Dr Barry Iacopetta for critical reading of the manuscript. This work was partly supported by grants from the Association Nationale de Recherche sur le SIDA (credit number 03/162) and from the Association pour la Recherche contre le Cancer (credit number 3301). J.E.B. was recipient of a fellowship from the Ministère Français de la Recherche (MRT).
Conflict of Interest statement. None declared.
|
REFERENCES |
|---|
|
TOPABSTRACTINTRODUCTIONRESULTSDISCUSSIONMATERIAL AND METHODSSUPPLEMENTARY MATERIALREFERENCES |
|---|
-
Aaltonen, L.A., Peltomäki, P., Leach, F.S., Sistonen, P., Pylkkänen, L., Mecklin, J.P., Järvinen, H., Powell, S.M., Jen, J., Hamilton, S.R. et al. (1993) Clues to the pathogenesis of familial colorectal cancer. Science, 260, 812–816.
[Abstract/Free Full Text] -
Thibodeau, S.N., Bren, G. and Schaid, D. (1993) Microsatellite instability in cancer of the proximal colon. Science, 260, 816–819.
[Abstract/Free Full Text] - Ionov, Y., Peinado, M., Malkhosyan, S., Shibata, D. and Perucho, M. (1993) Ubiquitous somatic mutations in simple repeated sequences reveal a new mechanism for colonic carcinogenesis. Nature, 363, 558–561.[CrossRef][Medline]
- Bronner, C.E., Baker, S.M., Morrison, P.T., Warren, G., Smith, L.G., Lescoe, M.K., Kane, M., Earabino, C., Lipford, J., Lindblom, A. et al. (1994) Mutation in the DNA mismatch repair gene homologue hMLH1 is associated with hereditary non-polyposis colon cancer. Nature, 368, 258–261.[CrossRef][Medline]
-
Papadopoulos, N., Nicolaïdes, N.C., Wei, Y.F., Ruben, S.M., Carter, K.C., Rosen, C.A., Haseltine, W.A., Fleishmann, R.D., Fraser, C.M., Adams, M.D. et al. (1994) Mutation of a MutL homolog in hereditary colon cancer. Science, 263, 1625–1629.
[Abstract/Free Full Text] - Fishel, R., Lescoe, M.K., Rao, M.R.S., Copeland, N.G., Jenkins, N.A., Garber, J., Kane, M. and Kolodner, R. (1993) The human mutator gene homolog MSH2 and its association with hereditary nonpolyposis colon cancer. Cell, 75, 1027–1038.[CrossRef][Web of Science][Medline]
- Leach, F.S., Nicolaïdes, N.C., Papadopoulos, N., Liu, B., Jen, J., Parsons, R., Peltomaki, P., Sistonen, P., Aaltonen, L.A., Nyström-Lahti, M. et al. (1993) Mutation of a MutS homolog in hereditary nonpolyposis colorectal cancer. Cell, 75, 1215–1225.[CrossRef][Web of Science][Medline]
-
Boland, C.R., Thibodeau, S.N., Hamilton, S.R., Sidransky, D., Eshleman, J.R., Burt, R.W., Meltzer, S.J., Rodrigues-Bigas, M.A., Fodde, R., Ranzani, G.N. et al. (1998) A National Cancer Institute workshop on microsatellite instability for cancer detection and familial predisposition: development of international criteria for the determination of microsatellite instability in colorectal cancer. Cancer Res., 58, 5248–5257.
[Abstract/Free Full Text] -
Duval, A. and Hamelin, R. (2002) Mutations at coding repeat sequences in mismatch repair deficient human cancers: toward a new concept of target genes for instability. Cancer Res., 62, 2447–2454.
[Abstract/Free Full Text] - Lykke-Andersen, J., Shu, M.-D. and Steitz, J.A. (2000) Human Upf proteins target an mRNA for nonsense-mediated decay when bound downstream of a termination codon. Cell, 103, 1121–1131.[CrossRef][Web of Science][Medline]
- Byers, P.H. (2002) Killing the messenger: new insights into nonsense-mediated mRNA decay. J. Clin. Invest., 109, 3–6.[CrossRef][Web of Science][Medline]
- Holbrook, J.A., Neu-Hilik, G., Hentze, M.W. and Kulozik, A.E. (2004) Nonsense-mediated decay approaches the clinic. Nat. Genet., 36, 801–808.[CrossRef][Web of Science][Medline]
- Ionov, Y., Nowak, N., Perucho, M., Markowitz, S. and Cowell, J.K. (2004) Manipulation of nonsense mediated decay identifies gene mutations in colon cancer cells with microsatellite instability. Oncogene, 23, 639–645.[CrossRef][Web of Science][Medline]
-
Duval, A., Rolland, S., Compoint, A., Tubacher, E., Iacopetta, B., Thomas, G. and Hamelin, R. (2001) Evolution of instability at coding and non-coding repeat sequences in human MSI-H colorectal cancers. Hum. Mol. Genet., 10, 513–518.
[Abstract/Free Full Text] - Gayet, J., Zhou, X.P., Duval, A., Rolland, S., Hoang, J.M., Cottu, P. and Hamelin, R. (2001) Extensive characterization of genetic alterations in a series of human colorectal cancer cell lines. Oncogene, 20, 5025–5032.[CrossRef][Web of Science][Medline]
- Liu, W., Dong, X., Mai, M., Seelan, R.S., Taniguchi, K., Krishnadath, K.K., Halling, K.C., Cunningham, J.M., Boardman, L.A., Qian, C. et al. (2000) Mutations in AXIN2 cause colorectal cancer with defective mismatch repair by activating b-catenin/TCF signaling. Nat. Genet., 26, 146–147.[CrossRef][Web of Science][Medline]
-
Duval, A., Rolland, S., Tubacher, E., Bui, H., Thomas, G. and Hamelin, R. (2000) The human T-cell transcription factor-4 gene: structure, extensive characterization of alternative splicings, and mutational analysis in colorectal cancer cell lines. Cancer Res., 60, 3872–3879.
[Abstract/Free Full Text] -
Markowitz, S., Wang, J., Myeroff, L., Parsons, R., Sun, L., Lutterbaugh, J., Fan, R.S., Zborowska, E., Kinzler, K.W., Vogelstein, B. et al. (1995) Inactivation of the type II TGF-ß; receptor in colon cancer cells with microsatellite instability. Science, 268, 1336–1338.
[Abstract/Free Full Text] - Malkhosyan, S., Rampino, N., Yamamoto, H. and Perucho, M. (1996) Frameshift mutator mutations. Nature, 382, 499–500.[CrossRef][Medline]
-
Park, J., Betel, D., Gryfe, R., Michalickova, K., Di Nicola, N., Gallinger, S., Hogue, C.W. and Redston, M. (2002) Mutation profiling of mismatch repair-deficient colorectal cancers using an in silico genome scan to identify coding microsatellites. Cancer Res., 62, 1284–1288.
[Abstract/Free Full Text] -
Ionov, Y., Yamamoto, H., Krajewski, S., Reed, J.C. and Perucho, M. (2000) Mutational inactivation of the proapoptotic gene BAX confers selective advantage during tumor clonal evolution. Proc. Natl Acad. Sci. USA, 97, 10872–10877.
[Abstract/Free Full Text] -
Chadwick, R.B., Jiang, G.L, Bennington, G.A, Yuan, B., Johnson, C.K., Stevens, M.W., Niemann, T.H., Peltomaki, P., Huang, S. and de la Chapelle, A. (2000) Candidate tumor suppressor RIZ is frequently involved in colorectal carcinogenesis. Proc. Natl Acad. Sci. USA, 97, 2662–2667.
[Abstract/Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  G. Patsos, S. Andre, N. Roeckel, R. Gromes, J. Gebert, J. Kopitz, and H.-J. Gabius Compensation of loss of protein function in microsatellite-unstable colon cancer cells (HCT116): A gene-dependent effect on the cell surface glycan profile Glycobiology, July 1, 2009; 19(7): 726 - 734. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. C. Chao and S. M. Lipkin Molecular models for the tissue specificity of DNA mismatch repair-deficient carcinogenesis Nucleic Acids Res., February 6, 2006; 34(3): 840 - 852. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||