Fig. 4.

Overexpression of AQP5 appears to increase cell proliferation in a phosphorylation-dependent manner. (A) Cell proliferation assay. Cell proliferation is significantly greater in stable cells with wild-type AQP5 or the N185D mutant than in stable cells with the S156A mutant or the empty vector. The experiment was performed three times. We found a statistically significant difference between cells expressing wild-type AQP5 and mutants/mock (t test, p < 0.001). (B–C) Tumor growth in athymic mice. Tumor growth was observed within 8 weeks for athymic mice subcutaneously injected with stable cells with wild-type AQP5 or the N185D mutant. No tumor growth is observed in mice injected with stable cells with the S156A cells or MOCK. Means and standard deviations of tumor volume were calculated from multiple observations in two groups of mice. Statistically significant difference were noted between cells expressing wild-type AQP5 and mutants/mock (t test, p < 0.001). Photographs of athymic mice 8 weeks after subcutaneous injection of stable cells with various hAQP5 constructs and MOCK are shown in (C). (D) AQP5 is phosphorylated in cancer cell lines and NSCLC tissues. AQP5 is phosphorylated in the two NSCLC cell lines examined, H1975 and H1838, and in 2 of 3 primary NSCLC tissues. No phosphorylation is detected in the three primary normal tissues.