Background & objective: Insulin-like growth factors (IGF) is one of polypeptide growth factors that stimulate proliferation, survival, and differentiation in many cell types; their signal pathways implicate development and progression of many kinds of malignant tumor, while less study were undergone on the roles of IGF-I and IGF-IR in bladder cancer genesis. This study was designed to investigate the expression of IGF-I and IGF-IR and proliferation cell nuclear antigen (PCNA) in human normal and carcinomatous bladder cancer, and to explore the mechanism of IGF-I and IGF-IR in cellular proliferation and tumorigenesis of bladder cancer.
Methods: Immunohistochemical methods were adopted to examine expression of IGF-I, IGF-IR, and PCNA in 88 cases with bladder cancer and 12 cases with normal bladder tissues. The relationship of expression of IGF-I and IGF-IR with various clinicopathological parameters and PCNA were analyzed.
Results: The protein expression rates of IGF-I and IGF-IR in bladder cancer were 73.9% and 59.1%, significantly higher than 33.3% and 16.7% in normal tissues, respectively(P< 0.05). Both two protein expression were association with PCNA indexes in bladder cancer (P< 0.05). There were close relationship among IGF-I expression and tumor recurrence (P< 0.05), IGF-IR and tumor grade, stage and recurrence (P< 0.05).
Conclusion: Abnormality of IGF-I-IGF-IR autocrine loop play an important role in development and progression of bladder cancer by promoting abnormal cellular proliferation. IGF-IR may be a marker for evaluating tumor biological behaviors.