Re: MicroRNA regulation of oncolytic herpes simplex virus-1 for selective killing of prostate cancer cells

Bioinformatics-Assisted Extraction of All PCa miRNAs and their Target Genes

INTRODUCTION

To retrieve, and classify PCa miRNAs and identify the functional relationship between miRNAs and their targets through literature collection with computational analysis.

BACKGROUND

MicroRNAs play a role in gene regulation, which can either repress or activate the gene. Hence, the functions of miRNAs are dependent on the target gene. This study will be the first of its kind to combine computational analysis with corpus PCa data. Effectively, our study reported the huge number of miRNAs associated with PCa along with functional information.

OBJECTIVE

The identification and classification of previously known full PCa miRNAs and their targets were made possible by mining the literature data. Systems Biology and curated data mining assisted in identifying optimum miRNAs and their target genes for PCa therapy.

METHODS

PubMed database was used to collect the PCa literature up to December 2021. Pubmed. mineR package was used to extract the microRNAs associated articles and manual curation was performed to classify the microRNAs based on the function in PCa. PPI was constructed using the STRING database. Pathway analysis was performed using PANTHER and ToppGene Suite Software. Functional analysis was performed using ShinyGO software. Cluster analysis was performed using MCODE 2.0, and Hub gene analysis was performed using cytoHubba. The genemiRNA network was reconstructed using Cytoscape.

RESULTS

Unique PCa miRNAs were retrieved and classified from mined PCa literature. Six hundred and five unique miRNAs from 250 articles were considered as oncomiRs to trigger PCa. One hundred and twenty unique miRNAs from 118 articles were considered Tumor Suppressor miRNAs to suppress the PCa. Twenty-four unique miRNAs from 22 articles were utilized as treatment miRNAs to treat PCa. miRNAs target genes and their significant pathways, functions and hub genes were identified.

CONCLUSION

miR-27a, miR-34b, miR-495, miR-23b, miR-100, miR-218, Let-7a family, miR-27a- 5p, miR-34c, miR-34a, miR-143/-145, miR-125b, miR-124 and miR-205 with their target genes AKT1, SRC, CTNNB1, HRAS, MYC and TP53 are significant PCa targets.

Targeting human breast cancer cells by an oncolytic adenovirus using microRNA-targeting strategy

MicroRNA-targeting strategy is a promising approach that enables oncolytic viruses to replicate in tumor cells but not in normal cells. In this study, we targeted adenoviral replication toward breast cancer cells by inserting ten complementary binding sites for miR-145-5p downstream of E1A gene. In addition, we evaluated the effect of increasing miR-145 binding sites on inhibition of virus replication. Ad5-control and adenoviruses carrying five or ten copies of miR145-5p target sites (Ad5-5miR145T, Ad5-10miR145T) were generated and inoculated into MDA-MB-453, BT-20, MCF-7 breast cancer cell lines and human mammary epithelial cells (HMEpC). Titer of Ad5-10miR145T in HMEpC was significantly lower than Ad5-control titer. Difference between the titer of these two viruses at 12, 24, 36, and 48h after infection was 1.25, 2.96, 3.06, and 3.77 log TCID₅₀. No significant difference was observed between the titer of both adenoviruses in MDA-MB-453, BT-20 and MCF-7 cells. The infectious titer of adenovirus containing 10 miR-145 binding sites in HMEpC cells at 24, 36, and 48h post-infection was 1.7, 2.08, and 4-fold, respectively, lower than the titer of adenovirus carrying 5 miR-145 targets. Our results suggest that miR-145-targeting strategy provides selectivity for adenovirus replication in breast cancer cells. Increasing the number of miRNA binding sites within the adenoviral genome confers more selectivity for viral replication in cancer cells.

MicroRNA controlled adenovirus mediates anti-cancer efficacy without affecting endogenous microRNA activity

MicroRNAs are small non-coding RNA molecules that regulate mRNA translation and stability by binding to complementary sequences usually within the 3′ un-translated region (UTR). We have previously shown that the hepatic toxicity caused by wild-type Adenovirus 5 (Ad5WT) in mice can be prevented by incorporating 4 binding sites for the liver-specific microRNA, mir122, into the 3′ UTR of E1A mRNA. This virus, termed Ad5mir122, is a promising virotherapy candidate and causes no obvious liver pathology. Herein we show that Ad5mir122 maintains wild-type lytic activity in cancer cells not expressing mir122 and assess any effects of possible mir122 depletion in host cells. Repeat administration of 2×10¹⁰ viral particles of Admir122 to HepG2 tumour bearing mice showed significant anti-cancer efficacy. RT-QPCR showed that E1A mRNA was down-regulated 29-fold in liver when compared to Ad5WT. Western blot for E1A confirmed that all protein variants were knocked down. RT-QPCR for mature mir122 in infected livers showed that quantity of mir122 remained unaffected. Genome wide mRNA microarray profiling of infected livers showed that although the transcript level of >3900 different mRNAs changed more than 2-fold following Ad5WT infection, less than 600 were changed by Ad5mir122. These were then filtered to select mRNAs that were only altered by Ad5mir122 and the remaining 21 mRNAs were compared to predicted mir122 targets. No mir122 target mRNAs were affected by Ad5 mir122. These results demonstrate that the exploitation of microRNA regulation to control virus replication does not necessarily affect the level of the microRNA or the endogenous mRNA targets.