Abstract:

Background and purpose: Ovarian cancer-associated fibroblasts (CAF) are known to promote epithelial malignancy. The chemoattractant cytokine growth-regulated oncogene alpha (Gro-α) secreted from CAF has been reported to mediate the stroma-epithelia interaction in tumor microenvironment, leading to the development of epithelial ovarian cancer, however, the detailed mechanism is unknown.This study was to determine whether Gro-α could promote ovarian tumorigenesis through activating NF-кB nuclear translocation and VEGF expression in stromal fibroblasts. Methods: ELISA was used to measure the levels of Gro-α in two cancer-associated fibroblasts (CAF) and normal fibroblasts (NF) isolated from high-grade serous ovarian cancer or normal ovarian tissues. CAF conditioned medium (CM) or Gro-α was used to treat NF, while PS1145, the inhibitor of NF-кB, was used as control. NF-кB subunit p65 and vascular endothelial growth factor (VEGF) were detected by Western blot in cells after treatment. Xenograft tumors from nude mice were generated by injection of CAF, NF, or OVCA429 alone or OVCA429 mixed with CAF or NF, and by injection of OVCA429 mixed with NF cells that were treated with or without CAF-CM or Gro-α, or with NF cells that were treated with CAF-CM or Gro-α plus PS1145. The tumor growth curve was measured and the blood vessel density in xenograft tumor tissues was examined by histopathological analysis. Results: The levels of Gro-α were 5-6 folds higher in CAF than in NF. Treatment of NF with CAF-CM or Gro-α stimulated the nuclear translocation of NF-кB subunit p65, and the expression of VEGF, but suppressed the expression of thrombospondin 1, the antiangiogenesis factor, compared with control cells. However, treatment of NF with the NF-кB inhibitor PS1145 reversed these results. The animal assay revealed that CAF stimulated tumor growth stronger than NF, and NF treated with CAF-CM or Gro-α, but not along with PS1145, enhanced xenograft tumor growth through promoting angiogenesis. Conclusion: Ovarian CAF promotes the nuclear translocation of NF-кB and the expression of VEGF through Gro-α autocrine in tumor microenvironment to facilitate angiogenesis and ovarian cancer development.

Key words: Cancer-associated fibroblasts, Gro-α, NF-кB nuclear translocation, Vascular endothelial growth factor, Ovarian cancer