| Objective To investigate the prevalence of microsatellite instability (MSI) and the relationship with the clinicopathological characteristics in sporadic rectal cancer of Chinese Han population.Methods DNA from fresh-frozen paired samples of tumors and corresponding normal tissue from 93 rectal cancer patients was analyzed for MSI using Bethesda markers by PCR amplification.Results A total of 11 (12%) cancers demonstrated high-frequency microsatellite instability (MSI-H), while 59 were microsatellite stable (MSS) and 23 were low-frequency microsatellite instability (MSI-L). Most of the MSI-H tumors compared with MSI-L and MSS tumors were young age at diagnosis (P = 0.030 and 0.021), high histopathological grade (P = 0.026 and 0.009) and high level of preoperative serum carcinoembryonic antigen (CEA) (P = 0.023 and 0.019). For tumor stage, MSI-L tumors and MSS tumors were strikingly distinguishing (P = 0.001).Conclusions Prevalence of MSI-H in rectal cancer of Chinese Han population is higher than almost all other ethnic group reported previously. Objective To investigate the mutations of hTCF-4 gene exons 3-9 in sporadic rectal cancer with MSI.Methods Sequence analysis of the coding region of the exons 3-9 of hTCF-4 gene was carried out for these 11 MSI-H cases identified and 10 controls(5 MSS cases and 5 cases with normal mucosa).Results The result revealed several novel mutations and variants. In exon 4, one is a 4-position continuous alteration which caused amino acid change from Q131T and S132I (391insA, 392G＞A, 393A＞G and 395delC) and another nucleotide deletion (395delC) are present in MSI-H cases (5/10, 50% and 4/10, 40%, respectively) but completely absent in the controls.Conclusions The absence of these novel mutations and variants in the controls suggests a potential pathogenic effect, which might be intensively involved in sporadic rectal cancer patients with MSI-H. |
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