Cell-cycle control in urothelial carcinoma: large-scale tissue array analysis of tumor tissue from Maine and Vermont

Abstract

Background: Cell-cycle proteins are important predictive markers in urothelial carcinoma but may also exhibit exposure-specific heterogeneity.

Methods: Tumor tissue from 491 bladder cancer cases enrolled in the Maine and Vermont component of the New England Bladder Cancer Study was assembled as tissue microarrays and examined for aberrant expression of p53, p63, p16, cyclin D1, Rb, and Ki-67. The association between expression and histopathology, demographics, and cigarette smoking was examined using χ(2) tests, multivariable Poisson, and multinomial regression models.

Results: We found that overexpression of p53 and Ki-67 was associated with high-stage/grade tumors [relative risk (RR), 1.26; P(trend) = 0.003; and RR, 3.21; P(trend) < 0.0001, respectively], whereas expression of p63 and p16 was decreased in high-stage/grade tumors (RR, 0.52; P(trend) < 0.0001; and RR, 0.88; P(trend) = 0.04, respectively). No significant aberrations of cell-cycle proteins were identified using various smoking variables and multiple statistical models.

Conclusion: The results of this population-based study of histologically confirmed urothelial carcinomas show significant aberration of cell-cycle proteins p53, p63, p16, and Ki-67, but not Rb or cyclin D1. p53 showed the most significant heterogeneity with respect to tumor stage and grade, especially when stratified for different staining intensities using novel digital image analysis techniques. Our findings do not support that smoking modifies expression of cell-cycle proteins.

Impact: Our study shows significant heterogeneity in the expression of key cell-cycle proteins that are associated with disease progression in bladder cancer. Further studies may lead to the identification of biomarkers and their multiplexed interactions as useful prognostic and therapeutic targets.

Figure 1

Representative immunohistochemical staining for p53 in bladder tumors (×400 magnification). A, tumor with predominantly strong p53 staining. B, digital image analysis of A: red, strong (3+); orange, moderate (2+); yellow, weak (1+); blue, negative. C, tumor with predominantly negative and weak p53 staining. D, digital image analysis of C.

Figure 2

Representative immunohistochemical staining for Ki67 (A), cyclin D1 (B), p16 (C), and Rb (D) in bladder tumors (×400 magnification).