Aristolochic Acid I induces ovarian toxicity by inhibition of akt phosphorylation.

Aristolochic acids are natural products found in Chinese herbs of the Aristolochiaceae family. Aristolochic acid I (AAI) is a potent carcinogen and was found to be toxic in animal and clinical studies. Apoptosis is a rapid, selective process of physiological cell deletion that regulates the balance between cell proliferation and cell death and is induced by various kinds of damage. However, the toxicity of AAI during ovarian maturation in the mouse is unclear and is the subject of the present investigation. We used Chinese hamster ovary-K1 (CHO-K1) cells and an AAI injection mouse model: MTT assay was used to assess AA toxicity to cells; ovary size and weight were measured to determine the toxicity of AA to mouse ovary; western blot was used to assess apoptosis; TUNEL assay was used to evaluate apoptotic cell death; and immunohistochemistry was used to examine the local expression of apoptotic proteins in ovary tissue. We found that AAI significantly inhibits the viability of CHO-K1 cells and strongly induces apoptotic cell death in CHO-K1 cells and in mouse ovary. In addition, we observed that AAI markedly increases the expression of pro-apoptotic proteins, including Bax, caspase-3, caspase-9, and poly(ADP) ribose polymerase (PARP). In contrast, anti-apoptotic proteins, such as Bcl-2 and survivin, were decreased by AAI treatment. Furthermore, we observed that ovary size and weight were significantly reduced and that the number of ovulated oocytes was markedly suppressed in AAI-treated mice. These results suggest that AAI strongly induces toxic damage during ovarian maturation by inhibiting Akt phosphorylation-mediated suppression of apoptosis.

Targeted inhibition of phosphatidyl inositol-3-kinase p110ß, but not p110α, enhances apoptosis and sensitivity to paclitaxel in chemoresistant ovarian cancers.

The phosphatidylinositol 3-kinase (PI3K) pathway is one of the critical signaling cascades playing important roles in the chemoresistance of human cancer cells, including ovarian cancer. In this study, we investigated the potential of targeting the PI3K p110ß-isoform as a novel approach to overcome the chemoresistance in ovarian cancer. The effects on apoptosis, cell viability, proliferation and migration in chemoresistant ovarian cancer cell were determined following targeted p110ß inhibition by small interfering RNA (siRNA). Seven paclitaxel (PTX)-resistant sublines (SKpacs and A2780pac) were produced from SKOV3 and A2780 ovarian cancer cell lines. We, first, evaluated the expression of PI3K p110 isoforms in chemosensitive and chemoresistant ovarian cancer cell lines and patient specimens, and found that p110ß-isoform was significantly overexpressed both in a panel of ovarian cancer samples, and in PTX-resistant sublines compared with their parent cell lines. RNA interference-mediated p110ß silencing augmented PTX-mediated apoptosis (31.15 ± 13.88 %) and reduced cell viability (67 %) in PTX-resistant cells, whereas targeting p110α did not show a significant change in cell viability and apoptosis. In addition, p110ß silencing impaired cell proliferation (60 %) in PTX-resistant SKpac cells. We also found the combined treatment group with p110ß siRNA and PTX showed a significant inhibition of tumor growth of SKpac cells compared to the PTX-only treated group in a xenograft nude mouse model. Thus, the siRNA-mediated silencing of PI3K p110ß resensitizes PTX-resistant ovarian cancer cells, and may be a useful therapeutic strategy for PTX-resistant ovarian cancers.