Analysis of the Impact of GPX1 on Cancer and the Effect of GPX1 Stimulation and Inhibition in Human Cell Lines

Simpson, Ruth and Allinson, Sarah and Coogan, Michael (2022) Analysis of the Impact of GPX1 on Cancer and the Effect of GPX1 Stimulation and Inhibition in Human Cell Lines. Masters thesis, Biomedical and Life Sciences.

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Abstract

GPX1 is a selenoprotein which protects cells from damage by removing H2O2. GPX1 has a complex role in cancer development, both in promoting and protecting against cancer, and is therefore of great interest in cancer research. Bioinformatic analyses of cancer databases were used to investigate the expression of GPX1 and GPX1-interacting proteins across cancer types, as well as the effect of GPX1 expression on prognosis and chemoresistance. GPX1 production was stimulated in HaCaT, A431 and HeLa cells using sodium selenite (Na2SeO3) and measured at various timepoints using western blotting and flow cytometry. Na2SeO3-treated cells were treated with chemotherapeutic agents (cisplatin, doxorubicin, docetaxel) and H2O2, and changes to chemoresistance were measured using CyQuant and XTT assays. The interaction of a new platinum agent, PeroxiPlat, in vivo with GPX1 was investigated using flow cytometry and its inhibition of GPX1 was measured using two biochemical activity assays. GPX1 was overexpressed in the majority of cancers, and worsened prognosis for UVM, LGG, ACC, KICH and LAML patients. GPX1 was commonly overexpressed with GPX4, TP53, POLR2L, HSD17B10, and CTSD, many of which were involved in leukocyte activation. No significant correlation between GPX1 expression and chemoresistance was identified. Na2SeO3 supplementation significantly but transiently increased the level of GPX1, and increased chemoresistance, although results were inconsistent between assays. It was also found that PeroxiPlat may weakly penetrate cells and exerts a low level of GPX1 inhibition. GPX1 is clearly an important factor in cancer development and progression, and a potential target for therapy. Further research is needed to clarify the role of GPX1 in chemoresistance, although these results support existing evidence that GPX1 promotes multidrug resistance. Although PeroxiPlat does not appear to be a potent GPX1 inhibitor, its use as a fluorescent molecule warrants further investigation into the uptake and uses of PeroxiPlat.