Silencing of the cytokine receptor TNFRSF13B: A new therapeutic target for triple-negative breast cancer.

BACKGROUND

TNFRSF13B, TACI, is a member of the TNF receptor superfamily; it plays a key role in cancer cell proliferation and progression.

METHOD

Influence of silencing of human cytokine receptors on cell viability was screened by Luminescent Cell Viability Assay, after transfection of the siRNA library to find the maximum cell death superhits in both triple-negative MDA-MB-231 and double-positive MCF7 breast cells. The mode of cell death was investigated by dual DNA fluorescence staining. The expression of mRNAs of TACI, BAFF, BAFF-R, and APRIL was explored by qPCR. Immunocytofluorescence analysis was used to evaluate changes in TACI, Bcl-2, TNFR2, cyclin-D2, and PCNA. NF-kB p65, cell cycle, and necrosis/apoptosis (late and early) were analyzed by flow cytometry.

RESULTS

TACI is the most potent cytotoxic superhit resulted from high-throughput screening of the siRNA library, in both types of cells. Our findings indicated that silencing receptor TACI in both types of breast cancer cells led to significant cell death, after different intervals from siRNA transfection. Cell death mediators (TNFR2, Bcl-2, and NF-κB) were significantly decreased after TACI silencing. The key factors for cell division (Cyclin-D2 and PCNA) were significantly increased in silenced cells of both types but the cell cycle was arrested before the completion of mitosis. Expression of BAFF, BAFF-R and APRIL mRNA in TACI-silenced cells showed significant upregulation in MDA-MB-231 cells, while only BAFF-R and APRIL showed significant downregulation in MCF7 cells.

CONCLUSION

TACI silencing can be a new and promising therapeutic target for mesenchymal-stem like triple-negative breast cancer subtype.