Background & objective: In normal tissues and organs, cell apoptosis and proliferation maintain a homeostasis. Alterations of this physiologic balance may lead to malignant transformation of cells and tumorigenesis. This study was to investigate cell balance (ratio of apoptosis index to proliferation index, AI/PI) in colon cancer and its correlation with prognosis.
Methods: The apoptotic population and the proliferating population of colon cancer cells were quantitatively analyzed by Sub-G1 method and Ki-67/DNA bivariate analysis of flow cytometry. Cell proliferation was observed under confocal microscope. Kaplan-Meier method and log-rank test were used to analyze patients' survival.
Results: AI/PI ratio of cells was significantly higher in normal colon tissue than in colon adenoma tissue, Dukes' A colon cancer, Dukes' B colon cancer, and Dukes' C and D colon cancer (0.45+/-0.19 vs. 0.30+/-0.07, 0.29+/-0.11, 0.28+/-0.10, and 0.26+/-0.07, respectively, P < 0.01). AI/PI ratio showed a down-regulating trend in variables tested including tumor size, pathologic type, differentiation grade, Dukes' stage, and nodal involvement. AI/PI ratio of peripheral lymphocytes was significantly higher in colon cancer patients than in healthy people (0.64+/-0.11 vs. 0.49+/-0.12, P < 0.01). The expression of Ki-67 was observed in normal colon tissue, colon adenoma, and colon cancer under confocal microscope. Survival rate of patients with AI/PI ratio of < 0.285 (using the median value as the cutoff) and >/= 0.285 was not significantly different (P> 0.05).
Conclusions: Dysregulation (down-regulation or up-regulation) of cell balance between apoptosis and proliferation in colon cancer cells and lymphocytes might play an important role in tumorigenesis and tumor progression. AI/PI ratio can' t be used as a prognostic factor of colon cancer.