Expression of aquaporin 8 and phosphorylation of Erk1/2 in cervical epithelial carcinogenesis: correlation with clinicopathological parameters.

Overexpression of aquaporins (AQPs) has been reported in several human cancers. Extracellular signal-regulated kinases 1/2 (Erk1/2) are associated with tumorigenesis and cancer progression and may upregulate AQPs expression. In this study, we examined cervical tissue samples to establish the relationship between Erk1/2 and AQPs in cervical carcinoma by RT-PCR, Western blot and immunohistochemistry. We also examined the relationship between AQP8, Erk1/2 and clinicopathological variables in patients with cervical cancer. Our results showed that Erk1/2 was differentially expressed at the level of transcription and was most highly expressed in CIN samples (P < 0.05). At the level of translation, significant differences were seen in the expression of AQP8, Erk1/2 and P-Erk1/2 (P < 0.05). Expression was highest in CIN samples, where 80.9%, 76.6%, and 66% of samples were positive for AQP8, Erk1/2 and P-Erk1/2, respectively. Expression in cervical carcinoma samples was higher than in normal cervical tissues (P < 0.01). AQP8 expression was associated with the depth of invasion of cervical cancer cells, and the expression of Erk1/2 and P-Erk1/2 was increased in earlier clinical stages and in lymphatic metastasis. AQP8 expression was positively correlated with Erk1/2 expression in cervical cancer. In conclusions, increased AQP8, Erk1/2 and P-Erk1/2 expression may play a role in transformation of CIN into cervical cancer, and in early invasion and lymphatic metastasis of cervical cancer. These proteins could potentially be used as molecular markers for early diagnosis of cervical carcinoma.