A study of microRNAs as new prognostic biomarkers in anal cancer patients

MicroRNA (MiR) influences the growth of cancer by regulation of mRNA for 50-60% of all genes. We present as per our knowledge the first global analysis of microRNA expression in anal cancer patients and their prognostic impact.

Twenty-nine patients with T1-4 N0-3 M0 anal cancer treated with curative intent from September 2003 to April 2011 were included in the study. RNA was extracted from fresh frozen tissue and sequenced using NGS. Differentially expressed microRNAs were identified using the R-package DEseq2 and the endpoints were time to progression (TTP) and cancer specific survival (CSS).

Five microRNAs were significantly associated with 5-year progression free survival (PFS): Low expression of two microRNAs was associated with higher PFS, miR-1246 (100% vs. 55.6%, p = 0.008), and miR-135b-5p (92.9% vs. 59.3%, p = 0.041). On the other hand, high expressions of three microRNAs were associated with higher PFS, miR-148a-3p (93.3% vs. 53.6%, p = 0.025), miR-99a-5p (92.9% vs. 57.1%, p = 0.016), and let-7c-3p (92.9% vs. 57.1%, p = 0.016). Corresponding findings were documented for CSS.

Our study identified five microRNAs as prognostic markers in anal cancer. MiR-1246 and microRNA-135b-5p were oncoMiRs (miRs with oncogene effects), while miR-148a-3p, miR- 99a-5p, and let-7c-3p acted as tumour suppressors in anal cancer patients.