PIWIL genes in hepatocellular carcinoma: a multi-omics approach uncovering dysregulated expression and ceRNA networks in mice

This multi-omics study delves into the expression patterns of PIWIL genes and their correlation with hepatocellular carcinoma (HCC) progression, utilizing whole transcriptome sequencing, bioinformatics, and reverse transcription quantitative polymerase chain reaction (RT-qPCR) in mice. We identified differential expression levels of PIWIL genes between HCC and control tissues and analyzed their roles within the competing endogenous RNA (ceRNA) network related to regulatory non-coding RNA-mediated gene silencing (RNGS). Our findings showed that Piwil1 and Piwil4 were overexpressed while Piwil2 is underexpressed. As ceRNAs, specific lncRNAs, including Pvt1, Gas5, and BGIGI10090_38749, might sponge up miR-351-5p and miR-31-5p, promoting Piwil1 and Piwil4 expression, while miR-133b-3p, lacking ceRNA sponge absorption, continues to inhibit Piwil2. Through their interactions with PPI proteins encoded by RNGS genes, especially Dhx9, Drosha, Mov10, and Tdrd1, PIWI family members might play a multifaceted role in regulating gene expression and metabolic processes, thereby involving the development and progression of HCC. These interactions within the PPI network could influence the stability and activity of PIWIL proteins and contribute to the overall regulation of gene expression and HCC progression. In the RNGS, a diverse array of miRNAs, genes, lncRNAs, circRNAs, and pseudogenes have been observed, which are suggested to intricately interplay, potentially weaving a complex ceRNA regulatory network. Abnormally expressed miRNA-targeted genes in RNGS are associated with key biological processes, such as lipid metabolism and immune responses, crucial for tumor cell survival, and processes supporting tumor growth and invasion, like translation and cytoskeleton organization. This regulation is reflected in distinct KEGG pathways for downregulated and upregulated targets, highlighting the dualistic role of PIWIL genes in modulating HCC progression. The study concludes that PIWI family members have a correlation with HCC progression and play divergent roles in the pathogenesis, with overexpression of the Piwil1 and Piwil4 potentially promoting HCC progression and underexpression of Piwil2 likely suppressing tumor development. The ceRNA mechanism and PPI network are crucial in regulating the expression and function of PIWIL genes, respectively. The intricate ceRNA network potentially regulates the expression of miRNA-targeted genes in RNGS, which might be crucial for tumor survival and promotion, with impacts on immune responses and cell growth based on enriching results of dysregulated miRNA-targeted genes in HCC. By shedding light on the molecular intricacies of HCC, this multi-omics study underscores the pivotal roles of epigenetic regulations, especially the influence of PIWI family genes with other genes and ncRNAs in the RNGS process in HCC pathology. The findings offer valuable insights into the molecular mechanisms underpinning HCC, which may inform future research into potential targets for therapeutic intervention. The future research could benefit from integrating a diverse range of methodologies to further elucidate the roles of PIWIL genes in HCC progression, building upon the findings presented here.