Fibroblast growth factor signalling influences platinum chemoresistance in ovarian cancer by altering both epithelial-to-mesenchymal transition and the DNA damage response


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Hugh Nicholson1,Francesco Rao2,Gillian Smith1
1University of Dundee,2DC Biosciences Ltd.

Abstract

Background

Ovarian cancer is the most lethal gynaecological malignancy and the fifth most common cause of cancer related death. Patients initially respond well to combination platinum/taxane chemotherapy, however commonly develop chemoresistant disease. Previous studies have shown FGF1 to be overexpressed in cisplatin resistant ovarian cancer cell lines, where knockdown resensitises cells to platinum chemotherapy. This study investigates the mechanism of FGF1 induced platinum resistance in ovarian cancer cells.

Method

A lentiviral-based shRNA knockdown of FGF1 in A2780DPP platinum resistant ovarian cancer cells was confirmed by qRT-PCR analysis and Western Blot. To investigate phenotypic alterations, qRT-PCR analysis and Western Blotting was used to assess expression of genes associated with the development of mesenchymal morphology. To study the role of the DNA damage response in FGF1 induced platinum resistance, gH2AX immunofluorescence was used. The proteomic based Reverse Phase Protein Array was used to further characterise the role of FGF1 in platinum resistant ovarian cancer.

Results

A2780DPP cells develop mesenchymal morphology, coupled with overexpression of mesenchymal markers, including Vimentin and N-cadherin. Cell morphology and marker expression were reverted to epithelial phenotype upon FGF1 knockdown. Following exposure to cisplatin, A2780 cells show increased gH2AX foci, where A2780DPP cells lose this induction, which is recovered following FGF1 knockdown. RPPA analysis showed a decreased expression of 53BP1, a repair protein involved in response to DNA damage, in A2780DPP cells compared to A2780 cells, where upon FGF1 knockdown expression is returned to basal level.

Conclusion

FGF1 modulates cell morphology, inducing mesenchymal phenotype in chemoresistant ovarian cancer cells. This demonstrates a rationale for targeting FGF1 driven EMT in ovarian cancer to reverse drug resistance. FGF1 was observed to have a key role in modulating cellular response to DNA damage in chemoresistant ovarian cancer cells. Taken together, FGF signalling demonstrates a promising therapeutic target as well as chemotherapy response biomarker in ovarian cancer.