Docosahexaenoic Acid Sensitizes Leukemia Lymphocytes to Barasertib and Everolimus by ROS-dependent Mechanism Without Affecting the Level of ROS and Viability of Normal Lymphocytes.

The aim of the present study was: (i) to investigate the possibility of sensitizing leukemia lymphocytes to anticancer drugs using docosahexaenoic acid (DHA); (ii) to find combinations with synergistic cytotoxic effect on leukemia lymphocytes, without or with only very low cytotoxicity towards normal lymphocytes; (iii) and to clarify the role of reactive oxygen species (ROS) in the induction of apoptosis and cytotoxicity by such combinations. The study covered 15 anticancer drugs, conventional and new-generation. Well-expressed synergistic cytotoxic effects were observed after treatment of leukemia lymphocytes (Jurkat) with DHA in combination with: barasertib, lonafarnib, everolimus, and palbociclib. We selected two synergistic combinations, DHA with everolimus or barasertib, and investigated their effects on viability of normal lymphocytes, as well as on the production of ROS and induction of apoptosis in both cell lines (leukemia and normal). At the selected concentrations, DHA, everolimus and barasertib (applied separately) were cytotoxic towards leukemia lymphocytes, but not normal lymphocytes. In leukemia cells, the cytotoxicity of combinations was accompanied by strong induction of apoptosis and production of ROS. In normal lymphocytes, drugs alone and in combination with DHA did not affect the level of ROS and did not induce apoptosis. To our knowledge, the present study is the first to report synergistic ROS-dependent cytotoxicity between DHA and new-generation anticancer drugs, such as everolimus and barasertib, that is cancer cell-specific (particularly for acute lymphoblastic leukemia cells Jurkat). These combinations are harmless to normal lymphocytes and do not induce abnormal production of ROS in these cells. The data suggest that DHA could be used as a supplementary component in anticancer chemotherapy, allowing therapeutic doses of everolimus and barasertib to be reduced, minimizing their side-effects.

Regorafenib as a potential adjuvant chemotherapy agent in disseminated small colon cancer: Drug selection outcome of a novel screening system using nanoimprinting 3-dimensional culture with HCT116-RFP cells.

Colon cancer is one of the leading causes of cancer death worldwide. Adjuvant chemotherapy following primary surgical treatment is suggested to be beneficial in eradicating invisible disseminated small tumors in colon cancer; however, an effective drug remains to be developed. Recently, we reported a novel drug screening system using a nanoimprinting 3-dimensional (3D) culture that creates multicellular spheroids, which simulate in vivo conditions and, thereby, predict effective drugs in vivo. This study aimed to perform drug selection using our recently developed 3D culture system in a human colon cancer HCT116 cell line stably expressing red fluorescent protein (HCT116-RFP), to determine the most effective agent in a selection of clinically used antitumor agents for colon cancer. In addition, we confirmed the efficacy of the selected drug regorafenib, in vivo using a mouse model of disseminated small tumors. HCT116-RFP cells were cultured using a nanoimprinting 3D culture and in vitro drug selection was performed with 8 clinically used drugs [bevacizumab, capecitabine, cetuximab, 5-fluorouracil (5-FU), irinotecan, oxaliplatin, panitumumab and regorafenib]. An in vivo study was performed in mice bearing HCT116-RFP intraperitoneally disseminated small tumors using 3'-[18F]-fluoro-3'-deoxythymidine-positron emission tomography and fluorescence microscopy imaging to evaluate the therapeutic effects. Regorafenib was determined to be the most effective drug in the 3D culture, and significantly inhibited tumor growth in vivo, compared to the untreated control and 5-FU-treated group. The drug 5-FU is commonly used in colon cancer treatment and was used as a reference. Our results demonstrate that regorafenib is a potentially efficacious adjuvant chemotherapeutic agent for the treatment of disseminated small colon cancer and, therefore, warrants further preclinical and clinical studies.