Investigation of the effect of quercetin and CD3254 combination on apoptosis via NR4A1/RXR in breast and colon cancer cell lines

Breast cancer is a disease that occurs with tumor formation due to breast cells changing and proliferating uncontrollably. Colon cancer is abnormal cell growth that occurs in the colon or rectum (large intestine). NR4A1 is a member of the NR4A subfamily of nuclear receptors and plays important roles in the development, differentiation, and survival of various cell types, including immature T cells, neurons, and cancer, as well as in apoptosis. Quercetin is a plant flavonol from the flavonoid group of polyphenols. Quercetin, which is also used for therapeutic purposes due to its anti-inflammatory and anti-carcinogenic effects, is found in many fruits, vegetables, leaves, seeds and grains. RXR is one of the retinoic acid receptors and they activate the appropriate gene region by binding with nuclear receptors (NR). In this study, it was aimed to investigate the effect of NR4A1 and RXR heterodimer on apoptosis and status of NR4A1, RXR, and the apoptotic proteins Cyt-C and Bcl-2 in human MCF-7 breast and HCT-116 colon cancer cells treated with quercetin and the RXR agonist CD3254. Cytotoxicity in MCF-7 and HCT-116 cells treated with quercetin and CD3254 was examined by the CCK-8 method, and the 24-hour IC50 value in the MCF-7 cell line was determined to be 68.3 µM and 48-hour IC50 was 97.74 µM. However, no activity of quercetin was observed in HCT-116 cells. The effectiveness of CD3254 has not been shown in either cell line. After 20 and 100 µM quercetin application in MCF-7 cells, NR4A1, RXR, Bcl-2, Cyt-C, Ki-67 and Grp-78 proteins were examined using immunofluorescence (IF) and immunocytochemistry (IHC) methods. Changes in the levels of NR4A1 and Bcl-2 proteins were detected in MCF-7 cell lysates by Western blot technique. Apoptotic positivity was evaluated statistically by TUNEL staining. Our data showed that quercetin decreased NR4A1 and increased RXR. TUNEL staining results showed a low rate of apoptotic positivity. However, a decrease in the number of cells was observed as a result of 100 µM dose application of quercetin. Additionally, cell morphologies indicating different cell death pathways were also demonstrated