Effect of histone deacetylase 8 gene deletion on breast cancer cellular mechanism in vitro and in vivo study.

Background: Triple-negative breast cancer (TNBC) is the most aggressive type of cancer without any approved targeted therapy. Epigenetic processes have a pivotal role in cancer cell progression and while histone deacetylase 8 (HDAC8) has been proven as a potential oncogene in breast cancer, its underlying molecular mechanism is not known. Therefore, the present study, aimed to evaluate the underlying mechanism of the HDAC8 carcinogenesis in breast cancer progression.

Methods: The potential role of HDAC8 in cancer cell processes such as apoptosis, invasion, migration, angiogenesis, and cancer stem cells (CSCs) markers were evaluated by using flow cytometry Annexin V-FITC/propidium iodide (PI), reverse transcription-polymerase chain reaction (RT-qPCR), Matrigel-coated transwell plates and wound healing assay on both cell lines. The impact of HDAC8 on tumor development was also studied using a breast cancer xenograft model.

Results: HDAC8 expression was significantly downregulated in the cell lines, post-transfection with KO-vector. Downregulation of HDAC8 dramatically decreased cell migration, angiogenesis, and invasion while inducing apoptosis in MDAMB-468 and MDA-MB-231 cell lines. HDAC8 knocked out TNBC cell lines had lower levels of cancer stemness markers, such as prominin-1 (CD133), CD44, BMI1, and Aldehyde dehydrogenase 1 (ALDH1). Additionally, the knockout of HDAC8 inhibited tumor growth in a breast cancer xenograft model.

Conclusion: The findings show that knocking out HDAC8 retains several anticancer actions in BC cells, such as inducing apoptosis, reducing migration, invasion, angiogenesis and removing CSCs markers.