Abstract:
The incidence and mortality of cancer are rapidly growing worldwide. It is expected to become the major cause of death in the 21st century. The pathologic role of CD276 (B7-H3) has already been established in different types of cancer. In Urothelial Carcinoma, the relationship between CD276 and immune evading mechanisms, as well as the invasive and migrative potential of the tumor has also been described. Studies indicate a higher expression of CD276 mRNA, as well as CD276 protein inside and outside the tumor cell in correlation with poor prognosis and decreased overall survival of patients. This leads to the assumption that dysregulation of CD276 may be an important factor in development and progression of UC. It was also shown that miRNAs may play a major role in regulation of CD276 mRNA expression. Especially miRNA 29c could function as a tumor suppressor by decreasing CD276 mRNA levels in tumor cells. To confirm the hypothesis of dysregulated CD276 expression in selected and established urothelial carcinoma cell (UCC) lines, expression of CD276 at the level of transcription into mRNA, translation into protein and presentation at the cell surface were analyzed and compared to somatic urothelial cells. Correlation of this data was investigated to show the relationship of the amounts of expression with each other. Furthermore, miRNA expression in cell lines with high, moderate and low expression of CD276 protein were analyzed to confirm a possible regulatory role. The expression of CD276 was explored in vitro on eight urothelial carcinoma cell lines (UM-UC) in comparison to normal urothelial cells (UCs) by RT-qPCR, Western blotting, and flow cytometry. Cell proliferation observed and calculated. The expression of miRNA 29c and miRNA 187 was explored in vitro on seven urothelial carcinoma cell lines (UM-UC) in comparison to somatic urothelial cells by RT-qPCR. All cell cultures were tested for a possible contamination with mycoplasma bacteria. Expression of CD276 on cell surfaces was elevated on UM-UCs when compared to somatic urothelial cells. In UM-UCs, CD276 transcripts correlated moderately positive with CD276 protein expression (ρ = 0.660) and strongly positive with CD276 surface-expression (ρ = 0.810). CD276 mRNA expression (ρ = -0.475) and CD276 protein expression (ρ = -0.417) had a significant negative correlation with proliferation, while a significant correlation between proliferation and cell surface expression was not observed in UM-UCs. Relative median expression of miRNA 29c in UCC cell lines was significantly lower compared to somatic urothelium. mir187 showed variable expressions patterns. The expression of CD276 on UM-UC bladder tumor cell surfaces is elevated. Slow proliferating UM-UC cells express more CD276 mRNA and protein than fast proliferating cells. In patients, slow proliferating and high-CD276-expressing cells may be tumor stem cells and evade immune surveillance. However, cancer therapy targeting CD276 may be effective in the treatment of slow proliferating tumor cells. MiRNA 29c might be a possible therapeutic target
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