My research project focuses on the discovery and validation of gene targets for improving chemotherapeutics in prostate adenocarcinoma. Previous research has identified that the shRNA knockdown (KD) of 3′-phosphoadenosine 5′-phosphosulfate (PAPS) synthase 1 (PAPSS1), an enzyme that catalyzes the synthesis of biologically active PAPS, to have sensitizing effects to chemotherapy drug cisplatin in lung cancer cell lines, but such chemo-sensitization was not observed in normal epithelial cells. We intended to build on the previous discovery by elucidating the inhibition of the PAPSS1 chemo-sensitization effect in prostate cancer cell lines. We hypothesized that CRISPR-Cas9-mediated knockout (KO) of PAPSS1 in the PAPSS2-deleted prostate cancer cell line could have a better sensitization effect as it is more complete inhibition than KD.

I began by cell line genetic background analysis using Broad Institute’s Cancer Cell Line Encyclopedia (CCLE), where I identified LNCaP as the ideal candidate cell line for our experiments due to its genetic background as representative of the patient group that we are focusing on. I generated and maintained PAPSS1 CRISPR-Cas9-mediated KO cell groups, investigated the proliferation rates, and examined chemotherapy drug efficiency in cancer cell lines with different genetic backgrounds.

In vitro drug assessment showed that PAPSS1 KO enhanced the efficiency of the DNA damaging agent cisplatin, but such sensitization is not found in drugs with different mechanisms of action, such as the mitotic inhibitor docetaxel. The mechanism of action of cisplatin is the ability to crosslink DNA bases, leading to DNA damage and inducing apoptosis in cancer cells. Therefore, PAPSS-mediated sulfation reactions might be involved in facilitating DNA repair to block the action of DNA damaging agents. With limited knowledge on the significance of sulfation, this correlation between PAPSS-mediated sulfation and enhancement in chemotherapy efficiency is worth investigating and pursuing therapeutically in prostate cancer.