Docosahexaenoic acid (DHA) impairs hypoxia-induced cellular and exosomal overexpression of immune-checkpoints and immunomodulatory molecules in different subtypes of breast cancer cells

Abstract

Background Tumor cells express immune-checkpoint molecules to suppress anti-tumor immune responses. In part, immune evasion takes place by secreting exosomes bearing immune-checkpoint and immunomodulatory molecules and their inducing and/or regulating agents e.g., microRNAs (miRs). This study aimed to evaluate the effects of omega-3 fatty acid, docosahexaenoic acid (DHA), on the expression of some selected immune-checkpoint and immunomodulatory molecules and their regulating miRs under both normoxic and hypoxic conditions in triple negative (TNBC) invasive and triple positive non-invasive breast cancer cell lines. Methods MDA-MB-231 and BT-474 cells were treated with 100 µM DHA under hypoxic and normoxic conditions for 24 h. Exosomes were isolated by ultracentrifuge and confirmed by electron microscope and anti-CD9, -CD63, -CD81 immunoblotting. Total RNA from cells and exosomes were extracted and expression of CD39, CD73, CD47, CD80, PD-L1, B7-H3, B7-H4 genes and their related miRs were evaluated by quantitative Real-time PCR. Results This study showed significant over-expression of immune-checkpoint and immunomodulatory molecules under hypoxic condition. Treatment with DHA resulted in a significant decrease in immune-checkpoint and immunomodulatory molecule expression as well as an upregulation of their regulatory miRNA expression. Conclusion DHA supplementation may be utilized in breast cancer therapy for down-regulation of cellular and exosomal immune escape-related molecules.

Cellular Basis of Adjuvant Role of n-3 Polyunsaturated Fatty Acids in Cancer Therapy: Molecular Insights and Therapeutic Potential against Human Melanoma

“…For instance, DHA has been shown to induce apoptosis in cancer cells, regulate the cell cycle, and enhance the effectiveness of the immune system against tumor cells. Additionally, DHA can impact signaling pathways such as PI3K/Akt and modulate the expression of immune checkpoints [44][45][46][47]. However, while these findings are promising, comprehensive in silico analyses and simulations are needed to explore the specific mechanisms on melanoma cells.…”