Pingxiao capsule inhibits lung metastasis of triple-negative breast cancer and sensitizes breast cancer to radiotherapy.

Objectives: To investigate the anticancer effect of Pingxiao capsule (, PXC) on the treatment of breast cancer and .

Methods: The inhibition of PXC on cell viability and proliferation was determined by cell counting kit-8, EdU assay and colony formation assay, respectively. The effect of PXC on cell apoptosis was detected by using flow cytometry. The suppression of PXC on cell migration and invasion was investigated by chamber assay. To investigate the underlying molecular mechanisms, the expression of proteins related to epithelial to mesenchymal transition (EMT) was analyzed by Western blotting in breast cancer cells and by immunohistochemistry in tumor tissues. The anticancer effect of PXC was evaluated by using MDA-MB-231 xenograft model and 4T1 metastatic breast cancer model.

Results: Our results indicated that triple-negative breast cancer (TNBC) cell lines MDA-MB-231 and MDA-MB-468 were sensitive to PXC. PXC potently inhibited the proliferation, colony formation, migration, and invasion of MDA-MB-231 and MDA-MB-468 cells . Then, MDA-MB-231 xenograft model depicted that PXC significantly reduced tumor size and weight compared with Control. 4T1 lung metastasis model showed that PXC significantly inhibited breast cancer cell spreading to lungs in mice. Mechanistically, PXC inhibited EMT process by reducing cadherin turnover in TNBC. Furthermore, PXC in combination with 8 Gy X-ray treatment obviously promoted the induction of apoptosis, and suppressed cell proliferation.

Conclusion: PXC could inhibit the proliferation and invasion of TNBC both and , and exerted its anti-metastatic effect by regulating cadherin turnover, Furthermore, it sensitized the TNBC cells to radiotherapy. The data supported further development of PXC as an adjuvant-therapy agent for TNBC.