Melittin inhibits the expression of key genes involved in tumor microenvironment formation by suppressing HIF-1α signaling in breast cancer cells

HIF-1 alpha has critical roles in the formation of tumor microenvironment by regulating genes involved in angiogenesis and anaerobic respiration. TME fuels tumors' growth and metastasis and presents therapy with several challenges. Therefore, we aimed to investigate if Melittin disrupts HIF-1 alpha signaling pathway in breast adenocarcinoma cell line MDA-MB-231. Breast adenocarcinoma cell line MDA-MB-231 was cultured in the presence of different doses of Melittin, and MTT assay was carried out to measure Melittin's cytotoxic effects. Cells were exposed to 5% O-2 to mimic hypoxic conditions and Melittin. Western blot was used to measure HIF-1 alpha protein levels. Gene expression analysis was performed using real-time PCR to measure relative mRNA abundance of genes involved in tumor microenvironment formation. Our results revealed that Melittin effectively inhibits HIF-1 alpha at transcriptional and translational/post-translational level. HIF-1 alpha protein and mRNA level were significantly decreased in Melittin-treated groups. It is found that inhibition of HIF-1 alpha by Melittin is through downregulation of NF kappa B gene expression. Furthermore, gene expression analysis showed a downregulation in VEGFA and LDHA expression due to inhibition of HIF-1 alpha protein by Melittin. In addition, cell toxicity assay showed that Melittin inhibits the growth of MDA-MB-231 cell line through activation of extrinsic and intrinsic apoptotic pathways by upregulating TNFA and BAX expression. Melittin suppresses the expression of genes responsible for formation of TME physiological hallmarks by suppressing HIF-1 alpha signaling pathway. Our results suggest that Melittin can modulate tumor microenvironment by inhibition of VEGFA and LDHA.

Automated summary

Melittin effectively inhibits HIF-1 alpha signaling pathway in breast adenocarcinoma cell line MDA-MB-231, leading to decreased expression of VEGFA and LDHA. Additionally, Melittin inhibits cell growth through activation of apoptotic pathways in MDA-MB-231 cell line.