SMC1A: a novel candidate DNA damage biomarker in hair follicles


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Surbhi Kaul1,Alan Bilsland2,Chantevy Pou2,Joanna Birch2,Anthony Chalmers2,Fiona Thomson2,Jeff Evans2
1Institute of Cancer Science, Wolfson Wohl Cancer Research Centre, University of Glasgow,2University of Glasgow

Abstract

Background

Despite proliferation of targeted anti-cancer agents, for many diseases cytotoxic chemotherapy remains the main treatment option. Targeting DNA repair with agents such as PARP inhibitors is a promising approach to enhance chemotherapy efficacy. Robust pharmacodynamic biomarkers, ideally in tissues that can be sampled non-invasively, would assist drug development in this area. Immunofluorescent detection of phosphorylated H2AX in hair follicles has been reported, although this approach has high variability. Here, we identified SMC1A in a screen for novel candidate DNA damage biomarkers in hair follicles.

Method

The NanoString DNA repair expression panel was used to screen RNA extracted from X-irradiated and capecitabine/olaparib-treated hair follicles from 4 donors. Upregulated genes were further investigated using ddPCR and capillary-electrophoretic immunoassays. Furthermore, we performed preliminary development of a novel SMC1A hybridisation assay based on fluorescence polarization in liquid crystals.

Results

A time-course NanoString experiment in control and chemoradiation-treated follicles from a single donor showed altered expression of multiple DNA repair-related genes at 1-hour post-treatment. Follicles from 4 additional donors were treated and harvested at 1-hour post treatment. SMC1A was significantly upregulated by treatment across all donors in NanoString assays. In ddPCR assays, SMC1A levels were also upregulated in S24 and E2 glioblastoma cell lines after irradiation and altered in a further 7 donors, though some donors showed downregulation. Finally, protein from 5 donors analysed by capillary electrophoretic immunoassay (Protein Simple WES platform) showed SMC1A present in all donors. Downregulation occurred in most donors at the protein level.

Conclusion

SMC1A was readily detectable in hair follicles from multiple donors across several platforms and significant expression changes occur after DNA damaging treatment. SMC1A forms a part of the cohesin complex which plays an essential function in cell cycle progression, DNA damage, and mediates pathogenesis of cancer. Thus, SMC1A is a potential novel pharmacodynamic biomarker for DNA-repair processes in hair follicles.