Role of Hydrogen Sulfide in Oncological and Non-Oncological Disorders and Its Regulation by Non-Coding RNAs: A Comprehensive Review.

Recently, myriad studies have defined the versatile abilities of gasotransmitters and their synthesizing enzymes to play a "Maestro" role in orchestrating several oncological and non-oncological circuits and, thus, nominated them as possible therapeutic targets. Although a significant amount of work has been conducted on the role of nitric oxide (NO) and carbon monoxide (CO) and their inter-relationship in the field of oncology, research about hydrogen sulfide (H2S) remains in its infancy. Recently, non-coding RNAs (ncRNAs) have been reported to play a dominating role in the regulation of the endogenous machinery system of H2S in several pathological contexts. A growing list of microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are leading the way as upstream regulators for H2S biosynthesis in different mammalian cells during the development and progression of human diseases; therefore, their targeting can be of great therapeutic benefit. In the current review, the authors shed the light onto the biosynthetic pathways of H2S and their regulation by miRNAs and lncRNAs in various oncological and non-oncological disorders.

Regulation of IGF2BP1 by miR-186 and its impact on downstream lncRNAs H19, FOXD2-AS1, and SNHG3 in HCC.

AIM: We have previously characterized oncogenic properties of IGF2BP1 in HCC, and its regulation by short noncoding RNAs (ncRNAs). Recent evidence suggests that IGF2BP1 itself may regulate long ncRNAs (lncRNAs). Therefore, this study aimed at exploring the interplay between IGF2BP1 and various upstream and downstream ncRNAs and its link to HCC pathogenesis. MATERIALS AND METHODS: Bioinformatic analysis was used to identify up- and downstream ncRNAs interacting with IGF2BP1. Huh-7 cells were transfected with siRNAs against IGF2BP1 and microRNA mimics. Relative gene expression was determined using RTqPCR and IGF2BP1 protein was quantified by western blot. Luciferase binding assay was used to explore the targeting of IGF2BP1 3'UTR. HCC tumorigenesis was measured by MTT assay, BrdU-incorporation assay, colony-forming assay, and scratch assay. KEY FINDINGS: Bioinformatic analysis identified three oncogenic lncRNAs - namely H19, FOXD2-AS1, and SNHG3 - potentially regulated by IGF2BP1. Knockdown of IGF2BP1 decreased the expression of all three oncogenic lncRNAs and inhibited malignant cell behaviors. miR-186 was revealed as a possible upstream regulator of IGF2BP1. miR-186 mimics decreased IGF2BP1 mRNA and protein levels. miR-186 was significantly lower while IGF2BP1 was elevated in cancerous tissues from ten HCC patients compared to five healthy controls. In addition, miR-186 mimics caused a downregulation of the oncogenic lncRNAs H19, SNHG3, and FOXD2-AS1 and a concomitant decrease in cell viability, proliferation, migration, and clonogenicity. SIGNIFICANCE: miR-186 may exert tumor suppressor effects in HCC by repressing oncogenic lncRNAs H19, SNHG3, and FOXD2-AS1 through its effect on IGF2BP1.

Interplay between microRNA-17-5p, insulin-like growth factor-II through binding protein-3 in hepatocellular carcinoma.

AIM: To investigate the effect of microRNA on insulin-like growth factor binding protein-3 (IGFBP-3) and hence on insulin-like growth factor-II (IGF-II) bioavailability in hepatocellular carcinoma (HCC). METHODS: Bioinformatic analysis was performed using microrna.org, DIANA lab and Segal lab softwares. Total RNA was extracted from 23 HCC and 10 healthy liver tissues using mirVana miRNA Isolation Kit. microRNA-17-5p (miR-17-5p) expression was mimicked and antagonized in HuH-7 cell lines using HiPerFect Transfection Reagent, then total RNA was extracted using Biozol reagent then reverse transcribed into cDNA followed by quantification of miR-17-5p and IGFBP-3 expression using TaqMan real-time quantitative PCR. Luciferase reporter assay was performed to validate the binding of miR-17-5p to the 3'UTR of IGFBP-3. Free IGF-II protein was measured in transfected HuH-7 cells using IGF-II ELISA kit. RESULTS: Bioinformatic analysis revealed IGFBP-3 as a potential target for miR-17-5p. Screening of miR-17-5p and IGFBP-3 revealed a moderate negative correlation in HCC patients, where miR-17-5p was extensively underexpressed in HCC tissues (P = 0.0012), while IGFBP-3 showed significant upregulation in the same set of patients (P = 0.0041) compared to healthy donors. Forcing miR-17-5p expression in HuH-7 cell lines showed a significant downregulation of IGFBP-3 mRNA expression (P = 0.0267) and a significant increase in free IGF-II protein (P = 0.0339) compared to mock untransfected cells using unpaired t-test. Luciferase assay validated IGFBP-3 as a direct target of miR-17-5p; luciferase activity was inhibited by 27.5% in cells co-transfected with miR-17-5p mimics and the construct harboring the wild-type binding region 2 of IGFBP-3 compared to cells transfected with this construct alone (P = 0.0474). CONCLUSION: These data suggest that regulating IGF-II bioavailability and hence HCC progression can be achieved through targeting IGFBP-3 via manipulating the expression of miRNAs.