FGF1 and HSP27 Interact to Modulate the DNA Damage Response in Chemoresistant Ovarian Cancer Cells


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Hugh A. Nicholson1,Michelle J. Ferguson2,Gillian Smith1
1University of Dundee,2NHS Tayside

Abstract

Background

Patients with ovarian cancer frequently present with advanced disease (FIGO stage 3 and 4) and are treated with surgery and chemotherapy. Although initially sensitive to platinum based chemotherapy regimens most patients eventually relapse with drug resistant disease, making their cancer incurable. We have previously demonstrated that Fibroblast Growth Factor 1 (FGF1) expression significantly inversely influences progression-free survival in ovarian cancer patients. Using paired platinum sensitive (A2780) and resistant (A2780DPP) ovarian cancer cell lines, we have additionally shown that knockdown of FGF1 in A2780DPP cells re-sensitises to platinum chemotherapy.

 

Method

We have used lentiviral shRNA-mediated stable knockdown of FGF1 in A2780DPP cells and immunofluorescence to quantitate yH2A.X foci formation in response to cisplatin challenge. Reverse Phase Protein Array (RPPA) was used to identify differential protein expression in A2780, A2780DPP and A2780DPP FGF1 knockdown ovarian cancer cells, and co-immunoprecipitation to investigate the interaction of HSP27 (HSPB1) with FGF1. Transient siRNA knockdown of HSPB1 was used to assess cell viability in response to cisplatin using MTT assay.

Results

FGF1-expressing A2780DPP cells are resistant to cisplatin and display enhanced recruitment of yH2A.X foci in response to cisplatin challenge, compared to sensitive A2780 cells which do not express FGF1. RPPA identified FGF1-dependent phosphorylation (S82) of HSP27 in ovarian cancer cells, where HSP27 co-immunoprecipitates with FGF1, an interaction which increases following acute cisplatin exposure. Like FGF1, knockdown of HSPB1 in A2780DPP cells re-sensitises cells to cisplatin. FGF1 and HSP27 translocate to the nucleus following acute cisplatin exposure, suggesting that HSP27 acts as a nuclear chaperone for FGF1, which promotes enhanced DNA repair.

Conclusion

FGF1 influences the kinetics of DNA damage signalling, where a cisplatin-inducible interaction with HSP27 is observed.

Pharmacological targeting of this interaction may affect the ability of FGF1 to influence DNA repair, and present new opportunities for ovarian cancer treatment.