Alterations in Expression of Cell Surface and Cell Cycle Signaling Molecules in Recurrent Nonmuscle Invasive Bladder Cancers: A Tissue Microarray Expression Analysis

Abstract

Background: Nonmuscle invasive bladder cancers (NMIBC) are one of the most common urological cancers having a high risk of recurrence and progression. Recurrent tumors may acquire certain molecular alterations responsible for progression of the tumors. Identification of these alterations is important to understand the pathobiology and guide further management. Aim: We studied the differences in expression of cell surface proteins and cell cycle signaling molecules in primary and recurrent NMIBC by immunohistochemistry (IHC) on tissue microarrays (TMA). Methods: Using FFPE tissue, TMA of 82 tumors (40 primary NMIBC and 47 recurrences) were constructed. IHC for growth factor receptors [epidermal growth factor receptor (EGFR), HER2/neu and FGFR3], cell adhesion molecules (E-cadherin and beta-catenin) and cell cycle pathway molecules (p53, p21/WAF1/Cip1 and Ki-67 proliferation index) was performed. A semiquantitative H-score (Histo-score; range 0-300) was calculated according to the intensity (0, negative; 1, weak; 2, moderate; and 3, strong) and percentage of cells stained. < 10% cells showing nuclear p21 expression was considered p21-loss. The differences in expression between the primary and recurrent tumors were analyzed using paired t test. Results: The mean age at presentation was 65.3 ± 13.6 years with a male predominance (n=36). The mean time to recurrence was 33.4 months (range 3-109). Progression in grade and/or stage was seen in 30 (75%) tumors. Time to recurrence was shorter in primary tumors with ≥ 5% Ki-67 proliferation index. There was no significant difference in expression of cell surface proteins between primary and recurrent tumors. Significant p21 loss was seen in recurrent tumors ( P = 0.03) and significantly correlated with loss of surface beta-catenin and nuclear p53 positivity ( P = 0.002). Ki-67 index was higher in recurrent tumors and also correlated with p53 positivity ( P = 0.007). Conclusion: We found no significant differences in expression of cell surface molecules in primary nonmuscle invasive bladder cancers and their recurrences. However, there were significant alterations in expression of molecules of cell cycle signaling pathway and cellular proliferation in recurrent tumors suggesting the role of cell cycle regulators as promising targets in these cancers.