## Abstract Microsatellite instability in sporadic colon cancer is associated with an improved prognosis. Recent studies, however, have suggested that microsatellite unstable cancers with mutations in the proapoptotic gene __BAX__ have a relatively poor prognosis, whereas those with mutations in tr
Alterations in cell proliferation and apoptosis in colon cancers with microsatellite instability
β Scribed by Frank A. Sinicrope; Rafaela L. Rego; Megan M. Garrity-Park; Nathan R. Foster; Daniel J. Sargent; Richard M. Goldberg; Myron Wiesenfeld; Thomas E. Witzig; Stephen N. Thibodeau; Lawrence J. Burgart
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- French
- Weight
- 195 KB
- Volume
- 120
- Category
- Article
- ISSN
- 0020-7136
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β¦ Synopsis
Abstract
Colon cancers with microsatellite instability (MSI) demonstrate a host immune response characterized by tumor infiltrating lymphocytes (TILs) that may exert effects upon tumor cell apoptosis and cell proliferation. Accordingly, we compared rates of apoptosis and cell proliferation in colon cancers with defective DNA mismatch repair and their association with phenotypic features and clinical outcome. Primary AstlerβColler stage B2 and C colon carcinomas (n = 329) were analyzed for MSI and for hMLH1 and hMSH2 protein expression. Apoptosis (TUNEL assay) and p53 expression were also analyzed by immunohistochemistry, and TILs were quantified by morphology. DNA ploidy and proliferation (PI: S phase + G~2~M) were evaluated using flow cytometry. MSIβH (n = 58) colon cancers showed increased TILs that were significantly associated with increased apoptosis, higher apoptosis to proliferation (AI/PI) ratios, reduced proliferative indices (PI) and diploid DNA content. Increased TILs (p = 0.036) and reduced PI (p = 0.042), but not AI or AI/PI, were associated with improved diseaseβfree survival. Tumors with MSIβH (p = 0.032) or loss of hMLH1 or hMSH2 proteins (p = 0.040), or diploidy (p = 0.0015), had better adjusted overall survival rates. Interestingly, similar rates of cell turnover and overlapping survival rates were found in diploid MSS/MSIβL tumors and in MSIβH cases. In conclusion, higher apoptosis/proliferation ratios and reduced cell proliferation are phenotypic features of MSIβH tumors that are associated with increased TILs, indicating an activated immune response that may contribute to their favorable survival rates. Β© 2006 WileyβLiss, Inc.
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