Peter Solár

Overexpression of biliverdin reductase A leads to ROS-independent sensitization of ovarian adenocarcinoma cells to gemcitabine

Biliverdin reductase A (BLVRA) is a key enzyme in bilirubin metabolism, where it reduces biliverdin to bilirubin. Bilirubin is a potent antioxidant that protects cells from oxidative stress. Therefore, reduced or deregulated BLVRA activity may contribute to increased oxidative DNA damage, which is one of the factors leading to the neoplastic transformation of cells. Human ovarian adenocarcinoma A2780 cells were transfected with a PiggyBac vector to achieve BLVRA overexpression. A2780 clones showing the most significant BLVRA gene overexpression were analyzed by proteomics and flow cytometry to assess rective oxygen species (ROS) production. Our results indicate that BLVRA overexpression increases the sensitivity of A2780 cells to doxorubicin and gemcitabine, with the most pronounced effect observed in the J clone. In this clone, the highest level of BLVRA overexpression correlated with significant alterations in the p53 signaling pathway. Upregulation of key effectors such as Bax and CDKN2A indicates a potential role for BLVRA in promoting pro-apoptotic responses. Moreover, BLVRA overexpression increased the sensitivity of A2780 cells to gemcitabine independently of ROS. This study broadens our understanding of BLVRA in ovarian cancer. In cells with intact p53 signaling, BLVRA overexpression can paradoxically enhance cytotoxic response to certain drugs, particularly gemcitabine.

Novel factors of cisplatin resistance in epithelial ovarian tumours

Ovarian tumours are these days one of the biggest oncogynecological problems. In addition to surgery, the treatment of ovarian cancer includes also chemotherapy in which platinum preparations are one of the most used chemotherapeutic drugs. The principle of antineoplastic effects of cisplatin (cis-diamminedichloroplatinum(II), CDDP) is its binding to the DNA and the formation of adducts. While DNA adducts induce the process of apoptosis, or inhibit the process of DNA replication, which prevents further division of tumour cells, various molecular mechanisms can reverse this process. On the other hand, with increasing scientific knowledge, it is becoming clearer that chemotherapy resistance is a very complex process. In this regard, factors and the amount of their expression may regulate the effect of resistance to chemotherapy. This review focuses on new molecular mechanisms and factors such as mitochondrial dynamics, epithelial-mesenchymal transition (EMT), cluster of differentiation, exosomes and others, that could be involved in the emergence of CDDP resistance.