OBJECTIVETo explore the viral etiology of human breast cancer to determine whether there are novel molecular targets for gene therapy of breast cancer and provide evidence for the research of gene therapy and vaccine development for breast cancer.

METHODSPCR was used to screen HPV16 and HPV18 oncogenes E6 and E7 in the SKBR3 cell line and in 76 paraffin embedded breast cancer tissue samples. RNA interference was used to knock down the expression of HPV18 E6 and E7 in SKBR3 cells, then the changes in the expression of cell-cycle related proteins, cell viability, colony formation, metastasis, and cell cycle progression were determined.

RESULTSHPV18 oncogenes E6 and E7 were amplified and sequenced from the SKBR3 cells. Of the patient samples, 6.58% and 23.68% were tested to be positive for HPV18 E6 and HPV18 E7. In the cell culture models, the knockdown of HPV18 E6 and E7 inhibited the proliferation, metastasis, and cell cycle progression of SKBR3 cell. The knockdown also clearly affected the expression levels of cell cycle related proteins.

CONCLUSIONHPV was a contributor to virus caused human breast cancer, suggesting that the oncogenes in HPV were potential targets for gene therapy of breast cancer.