Microwave hyperthermia enhances radiosensitization by decreasing DNA repair efficiency and inducing oxidative stress in PC3 prostatic adenocarcinoma cells.

PURPOSE: Radiotherapy (RT) is the primary treatment for prostate cancer (PCa); however, the emergence of castration-resistant prostate cancer (CRPC) often leads to treatment failure and cancer-related deaths. In this study, we aimed to explore the use of microwave hyperthermia (MW-HT) to sensitize PCa to RT and investigate the underlying molecular mechanisms. METHODS: We developed a dedicated MW-HT heating setup, created an in vitro and in vivo MW-HT + RT treatment model for CRPC. We evaluated PC3 cell proliferation using CCK-8, colony experiments, DAPI staining, comet assay and ROS detection method. We also monitored nude mouse models of PCa during treatment, measured tumor weight, and calculated the tumor inhibition rate. Western blotting was used to detect DNA damage repair protein expression in PC3 cells and transplanted tumors. RESULTS: Compared to control, PC3 cell survival and clone formation rates decreased in RT + MW-HT group, demonstrating significant increase in apoptosis, ROS levels, and DNA damage. Lower tumor volumes and weights were observed in treatment groups. Ki-67 expression level was reduced in all treatment groups, with significant decrease in RT + MW-HT groups. The most significant apoptosis induction was confirmed in RT + MW-HT group by TUNEL staining. Protein expression levels of DNA-PKcs, ATM, ATR, and P53/P21 signaling pathways significantly decreased in RT + MW-HT groups. CONCLUSION: MW-HT + RT treatment significantly inhibited DNA damage repair by downregulating DNA-PKcs, ATM, ATR, and P53/P21 signaling pathways, leading to increased ROS levels, aggravate DNA damage, apoptosis, and necrosis in PC3 cells, a well-established model of CRPC.

Effect of water activity on stress tolerance and biocontrol activity in antagonistic yeast Rhodosporidium paludigenum.

The aims of this study were to optimize the salt-adaptation conditions of the marine antagonistic yeast Rhodosporidium paludigenum and investigate the biocontrol activity of salt-induced cell suspensions of R. paludigenum on postharvest pathogens in fruits. Low water activity (a(w)=0.98, 0.97, 0.96, and 0.95) inhibited the growth of R. paludigenum in nutrient yeast dextrose broth, but the yeast grew better in the medium modified with NaCl solute than other nonionic solutes. R. paludigenum grown in 6.6% NaCl-modified medium had higher viabilities (92.1%) at low water activity (a(w)=0.95) than control (81.1%) after 48h incubation. The salt-adapted R. paludigenum also showed better viability than the un-adapted cells after being frozen, which may be related to the accumulation of intracellular trehalose. Moreover, the best biocontrol inhibition in pears and Chinese winter jujubes was obtained when R. paludigenum was grown in NaCl-modified medium. Therefore, this study implies that improving physiological inducement methods may be a promising strategy for accelerating commercialization of biocontrol agents.