Effects of sericin on oxidative stress and PI3K/AKT/mTOR signal pathway in cryopreserved mice ovarian tissue.

Ovarian tissue cryopreservation is an effective fertility protective strategy for preadolescent female cancer patients, whose tumor treatment cannot be delayed. In the present study, the effects of sericin, as an antioxidant, on mice ovarian tissue freezing and thawing were investigated. Mice ovarian tissues were cryopreserved and thawed in medium containing 0.5% or 1%sericin (w/v), and 0.1 mM melatonin. Then, the follicular morphology was observed. The levels of antioxidant enzymes were determined, including glutathione (GSH), glutathione peroxidase (GSH-Px), total superoxide dismutase (T-SOD), total antioxidant capacity (T-AOC) and catalase (CAT). Moreover, the levels of nitric oxide (NO), malondialdehyde (MDA) and lactate dehydrogenase (LDH) were also tested. Besides, apoptosis-related proteins Bcl-2 and Bax were determined. Our results showed that 1% sericin maintained follicular morphology, inhibited apoptosis, decreased MDA and NO levels, and boosted endogenous antioxidant enzyme levels, while had no significant effect on LDH levels. Furthermore, these effects may be related with the activation of the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of Rapamycin (mTOR) signaling pathway, as demonstrated by increased PI3K, p-AKT and mTOR levels. These findings demonstrate that 1% sericin may reduce oxidative stress and protect ovarian tissues during freezing and thawing via PI3K/AKT/mTOR signaling pathway.

PGC-1α activates SIRT3 to modulate cell proliferation and glycolytic metabolism in breast cancer.

Breast cancer is the leading cause of death among women. PGC-1α plays an important role in the regulation of metabolic reprogramming in cancer cells. SIRT3 has significant implications for tumor growth. In this study, we explored the roles of PGC-1α and SIRT3 in cell proliferation and mitochondrial energy metabolism alterations in breast cancer cells. The expression patterns of PGC-1α and SIRT3 were examined using qRT-PCR and western blotting analysis. MCF-7 and MDA-MB-231 cells were infected with adenovirus to overexpress or knock down the expression of PGC-1α and SIRT3. Cell viability and apoptosis were analyzed by CCK-8 and flow cytometry, respectively. Hexokinase 2, pyruvate kinase activities, as well as NAD+/NADH ratio and ATP concentration, were assessed by commercial kits. Glucose consumption was measured using the glucose oxidase method and lactic acid concentration was detected by lactate dehydrogenase kit. Expression levels of PGC-1 and SIRT3 were much lower in breast cancer patients, compared with the normal controls. Overexpression of PGC-1α or SIRT3 both significantly promoted the apoptosis and inhibited the proliferation in MCF-7 and MDA-MB-231 cells. Additionally, PGC-1α or SIRT3 also induced the inhibition of glycolysis metabolism. Moreover, the expression of SIRT3 was positively regulated by PGC-1α. Silencing SIRT3 partly reversed the negative effects of PGC-1α on glycolytic metabolism. These findings demonstrated that PGC-1α/SIRT3 regulated cell proliferation and apoptosis of breast cancer through altering glycolysis, which may provide novel therapeutic strategies for breast cancer.

Antioxidative effect of melatonin on cryopreserved ovarian tissue in mice.

Cryopreservation of ovarian tissues (OTs) has become the most effective way to preserve the fertility of female cancer patients. However, cryopreservation of OTs is still relatively at an experimental stage. The aim of study is to examine the effect of melatonin (MTL) on cryopreserved-thawed OTs. Fragments of OTs were cryopreserved in medium containing different concentrations (0 mM, 0.001 mM, 0.01 mM, 0.1 mM and 1 mM) of MLT. The endogenous enzymes (GSH-PX, GSH, SOD, CAT and T-AOC), MDA and ROS levels were all evaluated after cryopreservation. Our results showed that the 0.1 mM of MLT significantly improved the survival and diameter of follicles (P < 0.001). Meanwhile, the antioxidant enzymes activities (including GSH-PX, GSH, SOD, CAT and T-AOC) were enhanced and MDA content were significantly decreased in 0.1 mM of MLT group compared to other groups (P < 0.001). Additionally, compared to the control group, MTL of 0.1 mM resulted in a significantly lower ROS level. In conclusion, MLT protects the quality of cryopreserved OTs by decreasing oxidative stress level and the optimal concentration is 0.1 mM.