Objective        To study the synergistic effect of carboplatin combined with a PI3K inhibitor PF-04691502 (PF) on triple-negative breast cancer (TNBC) cell lines.       Methods        The effect of carboplatin and PF on TNBC cell lines (HCC1937 and MDA-MB 231) was measured by proliferation assay

colony formation assay

wound-healing assay and flow cytometry

respectively. The phosphorylation of Akt

which was a key protein in the progress of tumors

was detected by ELISA.       Results        Carboplatin and PF inhibited the proliferation

colony formation and migration of TNBC c

ell lines (P0.01)

and the phosphorylation of Akt in TNBC cells was also inhibited in a dose-dependent manner. Carboplatin combined with PF showed significantly synergistic effect in above assays (CI1). Flow cytometry results showed that PF could arrest the TNBC cells in G

1

phase

but carboplatin was non-specific for cell cycle.       Conclusion        Carboplatin combined with PF has synergistic anti-tumor effect on TNBC cell lines

suggesting that chemotherapy combined with PI3K inhibitor may effectively improve the therapeutic effect

reduce the dosage of chemotherapeutics  and decrease side effects.