Association between Caspase-3 and miR-155-5p expression in Kaposi's Sarcoma in Zambia

Background: Kaposi’s sarcoma (KS) is a vascular tumor driven by the human herpesvirus 8 (HHV8). KS is the most prevalent HIV/AIDS associated cancer in the world and second most prevalent cancer in Zambia with 16% incidence and 15% mortality. While little is known about the molecular mechanisms that drive this disease, data suggests that HHV8 promotes KS tumorigenesis through inhibition of apoptosis by HHV8-encoded micro RNAs. One example is miR-155-5p which has been shown to promote tumor progression and inhibit expression of pro-apoptotic caspase 3. This study therefore aims to investigate the correlation between miR-155-5p and caspase 3 in KS. Method: An analytical cross-sectional approach compared miR-155-5p and caspase-3 mRNA and protein expression in KS tissues versus adjacent controls using RT-PCR and immunohistochemistry respectively. Comparison of miR-155-5p and caspase-3 expression levels in KS and normal controls was done using the Wilcoxon rank-sum test while Spearman’s rank was used to test for any correlation. Results: No significant difference was observed between miR-155-5p and Caspase-3 mRNA expression in KS vs normal controls, however, there was a significant negative correlation between miR-155-5p and Caspase-3 mRNA in KS tissues. Furthermore, there was no significant difference in caspase 3 protein in KS vs normal controls. Importantly, a positive correlation between miR-155-5p and viral load in KS tissues was observed. Conclusion: This suggests a potential inverse relationship between miR-155-5p and caspase 3 mRNA in KS. Additionally, miR-155-5p expression may be regulated by HIV viral load however the nature of this regulation remains to be investigated.