The Identification of novel and specific biomarkers is crucial to diagnosis, and prognosis, in patients with prostate and breast cancer. Because cancer therapies have side effects in patients, discovering and potentially targeting specific biomarkers could promote the use of personalised approach for a more effective treatment.
Firstly, we have focused on the development of a monoclonal antibody-drug-based therapy, targeting prostate cancer stem cells (PCSCs), using a monoclonal antibody (mAb) previously generated in our laboratory against human endothelial protein C receptor (EPCR). PCSCs were isolated using lentivirus expressing the enhanced green fluorescent protein (EGFP) under NANOG-promoter generating two populations NANOG-EGFP+ and NANOG-EGFP- and analysed for EPCR expression.
No significant difference was observed in the expression of EPCR between NANOG-EGFP+ and NANOGEGFP- cell populations. A lack of conclusive correlation was observed between EPCR deficient cells with epithelial-mesenchymal transition (EMT) markers, cancer stem cells (CSCs), and stem cell markers. Finally, Gene Expression Profiling Interactive Analysis (GEPIA) was used to look at the tissue expression in normal and tumour tissue, showing high expression of EPCR in endothelial cells. Finally, based tissue expression profiling, EPCR is not a suitable candidate for antibody targeting as it would lead to off-target effects in multiple tissues, therefore no further experiments were designed using EPCR as a target biomarker.
Following this, a feasible study on the effect of Sperm-Associated Antigen 5 (SPAG5) chemoresistance and cancer progression in prostate and breast cancer was performed. The transcriptome and proteome of SPAG5 deficient were investigated in triple-negative breast cancer (TBC) MDA-MB-231 and androgenindependent prostate cancer DU145 cell lines, by RNA-sequencing and mass spectrometry (MS) analysis. Transcriptome was performed and a total of 2,201 differentially expressed genes (DEGs) in MDA-MB-231 SPAG5 deficient cells, while 907 DEGs DU145 SPAG5 deficient cells, versus control empty vector pLKO.1 cells, were identified. No significant differences in the cell cycle were observed in Doxorubicin and Epirubicin treatment DU145 and MDA-MB-231 SPAG5 deficient cells versus controls.
A list of the most statistically significant genes upregulated and downregulated was taken forward for verification for common and unique pathways, through free available online resources such as METASCAPE, and Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO). Using StatsPro free online sources proteomics analysis generated 230 differentially expressed proteins (DEPs) in MDA-MB- 231 SPAG5 deficient cells and 65 DEPs DU145 SPAG5 deficient versus control cells. Protein-protein interaction (PPI) network using Cytoscape has been conducted for enrichment KEGG analysis.
Cross-over data from MS and RNAseq upregulated and downregulated genes in MDA-MB-231 and DU145 SPAG5 deficient were compared to in silico data from cBioPortal tool. Interestingly, positive correlation was observed in genes involved in cell cycle, but also in genes involved in catalyse and biosynthesis of cholesterol.
Collectively those data offer a wider insight into the association of SPAG5 in cancer progression and its potential role not only in pathways involved in cell cycle but also how in lipid metabolism in cancer
