R.A. Assal

Destabilizing the interplay between miR-1275 and IGF2BPs by Tamarix articulata and quercetin in hepatocellular carcinoma.

Abstract Insulin-like growth factor-2 binding proteins (IGF2BPs) are oncogenic RNA-binding proteins, highly up-regulated in HCC, and were recently validated as direct targets of the tumour suppressor miR-1275. It is worth noting that around 47% of FDA approved anticancer drugs are derived from plants. Modulation by miRNAs and their cellular signalling cascades could constitute new pathways by which these phytochemicals exert their effects. This study aimed to investigate the potential use of Tamarix articulata, quercetin and epigallocatechin gallate (EGCG) in HCC and how these phytochemicals could epigenetically modulate the IGF axis using their impact on miR-1275. T. articulata ethyl acetate fraction significantly reduced the viability of Huh-7 cells compared to control cells. Treatment with T. articulata ethyl acetate fraction, quercetin and EGCG significantly enhanced miR-1275, while suppressed IGF2BP1 and IGF2BP3 mRNA expression levels. In summary, T. articulata, quercetin and EGCG have important implications for HCC molecular-targeted therapy through destabilizing the interplay between miR-1275 and the IGF axis.

A novel role of sONE/NOS3/NO signaling cascade in mediating hydrogen sulphide bilateral effects on triple negative breast cancer progression

Hydrogen sulphide (H2S) gas has been recognized as an intracellular mediator influencing an array of signaling pathways. Yet, the role of H2S in cancer progression has been controversial. This study aims to unravel the role of exogenous H2S in triple negative breast cancer (TNBC) and to further investigate any possible association of H2S mediated actions with the endogenous production of nitric oxide (NO) gas. A wide concentration range of NaHS (20-2000 μM) and a variable reaction time (2-72 h) were probed. A bell-shaped impact of H2S on TNBC cellular viability, proliferation, migration, invasion and colony forming ability was repeatedly observed in the aggressive TNBC cell lines, MDA-MB-231 but not in hormone receptor positive, MCF-7 cells. This bell-shaped effect was found to be shifted towards the left upon increasing the reaction time within the range of 2-24 h. However, this was totally opposed in case of continuous exposure (72 h) to exogenous H2S. An inverted bell-shaped effect of H2S on TNBC cellular growth, migration, proliferation and colony forming ability was shown. Moreover, this study provided the first evidence of a possible involvement of NO in mediating H2S actions in TNBC. Such intricate cross-talk was found to be orchestrated by the novel lncRNA, sONE and its down-stream target NOS3 building up a novel axis, sONE/NOS3/NO, that was shown to play a pivotal role in plotting the bilateral effect of H2S on TNBC progression. Finally, this study showed that low and continuous exposure of H2S serves as a novel, selective and effective strategy in harnessing TNBC oncogenic profile through cGMP dependent and independent pathways where alterations of cell cycle regulatory proteins such as TP53 and c-Myc was observed. Moreover, NaHS could repress TNBC migration and invasion capacities through repressing the intracellular adhesion molecule, ICAM-1. In conclusion, this study provides an insight about the role of exogenous H2S in TNBC cell lines highlighting a novel crosstalk between H2S and NO orchestrated by sONE/NOS3 axis.

Perturbation of IGF2BP1 Transcriptome upon the Interplay between miR-486-5p and let-7a

Background: Activation of IGF-1/IGF-1R signaling cascade is a hallmark in Hepatocellular carcinoma (HCC). In our previous work, we showed that miR-486-5p acts as a tumor suppressor miRNA in HCC mainly by vertically blocking IGF-1/IGF-1R axis and its downstream signaling mediators STAT3, mTOR and c-Myc. Recently, it was reported that the proto-oncogene c-Myc directly down-regulates the tumor suppressor miRNA, let-7a, especially in HCC and that let-7 directly targets the oncogenic RNA binding protein IGF2BP1. Aim: Therefore, the main aim of this study was to investigate the indirect interplay between microRNAs; miR-486-5p and miR-let- 7a through c-MYC thereby its effect on a vital member of IGF-axis, IGF2BP1, in HCC. Methods: Huh-7 cell lines were cultured and transfected using miR-486-5p mimics using lipofection technique. Forty-eight hours post transfection, total RNA was extracted, reverse transcribed into cDNA, and finally amplified and quantified using q-RT-PCR. Impact of miR-486-5p on cell cycle was assessed using cell cycle vectors carrying response elements for the cell cycle protein c-Myc. Results: Efficient delivery of miR-486-5p in Huh-7 cells was obtained, where mimicked cells showed more than 8000 folds increase in miR-486-5p expression level. Ectopic expression of miR- 486-5p in Huh-7 cells resulted in a significant decrease in c-Myc protein expression, an increase in the expression level of the tumor suppressor, let-7a and finally forcing the expression of miR-486-5p showed a significant repression of the oncogenic validated target of let-7a, IGF2BP1. Conclusions: This study shows a novel mechanism of action of the tumor suppressor miR-486-5p. MiR-486-5p was found to indirectly repress an essential member of IGF-axis, the oncogenic RNA binding protein IGF2BP1, mainly through decreasing c-MYC expression and up regulating let-7a expression.