ABSTRACT
OBJECTIVE To investigate the underlying mechanism of drug resistance to cisplatin and increasing the sensitivity to therapeutic drugs are key steps towards the improved treatment of patients with ovarian cancer. Gap junction (GJ) and connexin (Cx) are closely related to tumor formation, but the relationship between cisplatin resistance and GJ or Cx are undetermined. METHODS We established the cisplatin-resistant human ovarian cancer cell line A2780-CDDP over an 11-month period, with the concentration of cisplatin gradually increasing from 0.5 g·L-1 to 16 g·L-1. To explore the effect of GJ in the process of cisplatin resistance, we investigated GJ using a parachute dyecoupling assay in A2780- RI(1.2), A2780- RI(1.7), A2780- RI(2.9), A2780- RI(4.3) and A2780- CDDP cells. We further explored whether the Cxs responsible for GJ were related to cisplatin resistance. In A2780- RI(1.2), A2780-RI(1.7), A2780-RI(2.9), A2780-RI(4.3) and A2780-CDDP, we used q-PCR to analyze the levels of Cx43, Cx40, Cx37, and Cx32. To confirm the effect of Cx32 on cisplatin resistance, we knocked down Cx32 in A2780-CDDP cells with siRNA-Cx32. As GJ was decreased whereas Cx32 expression was elevated during the cisplatin resistance process, it drove us to explore the underlying mechanism. To resolve this issue, we extracted membrane-bound and cytoplasmic proteins from A2780 and A2780-CDDP cells. RESULTS Here we showed that cisplatin resistance was correlated to the loss of GJ and the upregulation of Cx32 expression. Enhancing GJ in A2780-CDDP cells could increase the apoptotic response to cisplatin treatment. Furthermore, although Cx32 expression was increased in A2780-CDDP cells, it was more localized to the cytoplasm rather than in the membrane, and knockdown of Cx32 in A2780-CDDP cells sensitized them to cisplatin treatment. CONCLUSION In summary, Cx32 is involved in cisplatin resistance, and cytoplasmic Cx32 plays an important role in chemoresistance.
ABSTRACT
<p><b>AIM</b>To study the effect of the recombined human growth hormone(rhGH) on secretory immunoglobulin A (sIgA), epidermal growth factor (EGF) in rats with obstructive jaundice.</p><p><b>METHODS</b>Sixty Wistar rats were randomly divided into four groups, sham-operated (group A), common biliary duct-ligated (group B), biliary duct-ligated plus rhGH-treat for one week (group C), biliary duct-ligated plus rhGH-treat for two weeks (group D), each group had 15 rats. Except group A, the rats of other groups were operated with biliary duct-ligated. Until two weeks after operation, the rats of group A and B were killed. After operation, the rats of group C were treated with rhGH hypodermic injection (0.75 U x kg(-1) x d(-1)) for one week, and then killed. The rats of D group were treated with rhGH hypodermic injection (0.75 U x kg(-1) x d(-1)) for two weeks, and then killed. All procedures were performed aseptically. Total bilirubin (TB), alkaline phosphatase (ALP), prealbumin(PA), insulin-like growth factor (IGF-1), sIgA, EGF were measured.</p><p><b>RESULTS</b>Compared with group A, in group B, C, D, serum level of PA, IGF-1 and sIgA, EGF level of gastric and intestinal juice were lower, but TB, ALP were higher, there were significant difference. Compared with group B, the rats with treatment of rhGH in group C and D had higher sIgA and EGF and lower intestinal bacterial translocation.</p><p><b>CONCLUSION</b>In objective jaundice rats, rhGH can protect their hepatic function, intestinal physical-barrier function and immune-barrier function, and reduce intestinal bacterial translocation.</p>