Objective: To study the mechanism how human sperm membrane-bound hyaluronidase (PH20) promotes the gowth of human breast cancer.
Methods: Full-length cDNA of human PH20 was transfected into human breast cancer cell line MDA231. The transfectant MDA231-PH20 was then implanted into the chorio-allantoic membrane (CAM) of chicken embryo to form a tumor. Four days after implantation, the tumors were resected to be weighed. The angiogenesis in tumor tissue was examined by immunohistochemistry. Trans-well cell culture was used to study the effect of MDA231-PH20 on the growth of adult bovine aortic endothelial cells (ABAE). The expression of fibroblast growth factor-2 (FGF-2) in the tumor cells was investigated by Western blotting. ELISA was used to examine the secretion of FGF-2 and hyaluronic acid. The same amount of empty vector pcDNA3, instead of PH20, was transfected into human breast cancer cell line MDA231 as control group.
Results: The average weight of tumor four days after implantation was 44.7 mg +/- 10.2 mg in the MDA231-PH20 group, and was 21.3 mg +/- 2.8 mg in the control group (t = 2.418, P = 0.038). Neogenetic vessels increased remarkably in MDA231-PH20 tumor tissues. The expression of FGF-2 protein was much higher in MDA231-PH20 cells. The FGF content and HA secretion were higher in the MDA231-PH20 group than in the control group (8.10 pg/ml +/- 1.56 pg/ml vs. 3.94 pg/ml +/- 0.82 pg/ml, and 1 220 ng/ml +/- 254 ng/ml vs. 462 ng/ml +/- 96 ng/ml, all P < 0.01). The growth of ABAE cells was significantly accelerated after co-culture with MDA231-PH20 transfectant.
Conclusion: PH20 may promote the growth of human breast cancer by accelerating the release of FGF-2 from tumor cells, decomposing HA into small fragments, and promoting angiogenesis.