EGCG-treated non-small cell lung cancer associated signature miRNA expression analysis: NGS approach for novel miRNA sequence detection

In the current study, we investigated the modulatory effect of epigallocatechin gallate (EGCG, an active derivative of green tea) on cellular miRNA expression and cell cycle proliferation in NSCLCs (A549). As the IC50 value of EGCG is approximately 304 μM, our studies support the resistance of A549 lung cancer cell by EGCG. In addition, it was interesting to observe its G0/G1 cell cycle arrest activity at 40μM EGCG treatment. So, in the present study, next-generation sequencing (NGS) was used to study the miRNA expression between the cancer control and EGCG-treated samples. A549 cells were treated with 40 μM and 100 μM EGCG. NGS was employed to study the differential expression of novel and known miRNAs. The data generated was analysed with computational approach to study and correlate the expression profiles of both known and novel miRNAs. Differential expression of known miRNAs was observed between control and EGCG-treated samples. Some putative novel miRNA sequences were also observed in the current study. The differential expression levels of putative novel miRNA sequences were estimated by counting the number of reads in the given dataset. Together the analysis of these miRNA profiles revealed log2-fold modulation in the expression levels. We detected 344, 337, and 346 number of known mature miRNAs in control, 40 μM EGCG treated, and 100 μM EGCG treated samples, respectively. We also reported 119, 126, and 125 number of putative novel mature miRNA sequences in control, 40 μM EGCG treated, and 100 μM EGCG treated samples, respectively. In conclusion, the analysis demonstrates that EGCG is actively involved in miRNA modulation in NSCLCs, which further attests to its chemoprotective role and could play a major role in therapeutic applications. A549 cells were treated with 40 micromolar or 100 micromolar concentration of EGCG for 24h. Total RNA was extracted from the samples. Small RNA sequencing was done by MiSeq, to study the differential miRNA expression profiles of known and putative novel miRNA sequences.