Hepatocellular carcinoma (HCC) is the fifth most common cancer worldwide and ranks third in the leading causes of cancer patients death. Cancer stem cells (HSCs), also known as tumor-initiating cells, have been reported in multiple subtypes of HCC and are considered as the master regulators of HCC initiation, chemotherapy drug resistance, tumor metastasis, and progression. In spite of their clinical importance, the detailed mechanism about how HSCs are intricately regulated in the molecular level remains elusive. MicroRNA (miRNA), a class of newly emerging small noncoding RNAs, has been demonstrated to serve as a vital player in modulating a number of biological activities ranging from embryogenesis to programmed cell death as well as the maintenance of HSCs. In this review, we synthesize these latest findings of miRNA regulation of HSCs and try to elucidate their mechanistic roles in orchestrating cellular equilibrium. This recent progress underlies the functional role of miRNA in cellular transformation of liver cancer, which has largely extended our knowledge how HSCs are controlled by miRNA network, and in the development of novel miRNA-based anticancer therapies specifically targeting HSCs in the coming future.

The epidemiological observational studies unveiled that aging is one of the risk factors for liver fibrosis, and the hepatic tissues in the elderly harbor more fibrotic lesions when compared to those in young people. Previous investigations found that TGFβ1 was elevated with aging and promoted liver fibrosis. However, the underlying mechanisms of aging and liver fibrosis remain largely unknown. CCl₄-induced liver fibrosis animal models were used in this study. The impact of NAT10 on liver fibrosis and cellular senescence was analyzed by using NAT10 overexpression or knockout hepatic stellate cell lines. The distribution of ac4C RNA modification was monitored by the acRIP-seq. The RNA-protein interaction was examined by the RNA immunoprecipitation. We demonstrated that the middle-aged mice were more susceptible to the CCl₄-induced liver fibrosis when compared to the young mice. Then, we found that RNA ac4C-modifying enzyme NAT10 was transcriptionally activated by TGFβ1/SMAD2/3 axis and highly expressed in the aging liver as well as liver fibrosis mouse model. Suppression of NAT10 by its inhibitor Remodelin or specific shRNA attenuated senescence and activation of hepatic stellate cells. Subsequent studies found that NAT10 directly triggered the ac4C RNA modification of TGFβ1 mRNA by physically interacting with the RNA-binding protein PTBP1, enhancing the stabilization of TGFβ1 mRNA and subsequent activation of TGFβ/SMAD signaling pathway. Animal studies demonstrated that inhibition of NAT10 by Remodelin significantly alleviated liver fibrosis and cellular senescence. Our study identified a previously unknown mechanism of how TGFβ1 drives cellular senescence and liver fibrosis through NAT10-mediated ac4C mRNA modification.

The receptor for growth hormone-releasing hormone (GHRH-R) has been shown to upregulate specifically in the ciliary and iris epithelial cells and infiltrating cells in the aqueous humor in a rat model of acute anterior uveitis. Treatment with GHRHR-R antagonist alleviates significantly these inflammatory responses. Herein we investigated whether the ciliary and iris epithelial cells can respond directly to lipopolysaccharide (LPS) without the influences of circulating leukocytes to produce inflammatory mediators through a GHRH-R mediated mechanism. In explant cultures of rat ciliary body and iris, LPS caused a substantial increase of GHRH-R in 24 h. Immunohistochemistry showed a localization of TLR4, the receptor for LPS, and an elevated expression of IL-6 and IL-1β in ciliary and iris epithelial cells after LPS treatment. LPS also elevated the level of IL-1β, IL-6, and iNOS and increased secretion of IL-1β and IL-6 from the explants. The GHRH-R antagonist, MIA-602, suppressed the elevated expression of IL-1β and IL-6, and reduced the release of IL-6. Such effects were not seen for the GHRHR agonist, MR-409. When co-cultured with leukocytes, expression of GHRH-R in the ocular explants was further enhanced during LPS treatment. Our results demonstrate a direct action of LPS on ciliary and iris epithelial cells to produce pro-inflammatory factors through a GHRH-R mediated mechanism, and suggest a role of these epithelial cells, in addition to the resident antigen presenting cells, in immune surveillance of the eye. Infiltrating leukocytes may enhance these inflammatory responses by regulating GHRH-R in ciliary and iris epithelial cells, in addition to their functions of synthesizing proinflammatory cytokines.

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are widely used for patients with EGFR-mutated lung cancer. Despite its initial therapeutic efficacy, most patients eventually develop drug resistance, which leads to a poor prognosis in lung cancer patients. Previous investigations have proved that non-coding RNAs including long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs) contribute to drug resistance by various biological functions, whereas how they regulate EGFR-TKI resistance remains unclear. In this study, we examined gene expression using the microarray technology on gefitinib-resistant NSCLC cells to obtain differentially expressed (DE) lncRNAs and mRNAs. A total of 45 DE-lncRNAs associated with overall survival and 1799 target DE-mRNAs were employed to construct a core lncRNA–miRNA–mRNA network to illustrate underlying molecular mechanisms of how EGFR-TKI resistance occurs in NSCLC. We found that target DE-mRNAs were mainly enriched in pathways involved in EGFR-TKI resistance, especially the target DE-mRNAs regulated by LINC01128 were significantly enriched in the PI3K/Akt signaling pathway, where the synergy of these target DE-mRNAs may play a key role in EGFR-TKI resistance. In addition, downregulated LINC01128, acting as a specific miRNA sponge, decreases PTEN via sponging miR-25-3p. Furthermore, signaling reactions caused by the downregulation of PTEN would activate the PI3K/Akt signaling pathway, which may lead to EGFR-TKI resistance. In addition, a survival analysis indicated the low expression of LINC01128, and PTEN is closely related to poor prognosis in lung adenocarcinoma (LUAD). Therefore, the LINC01128/miR-25-3p/PTEN axis may promote EGFR-TKI resistance via the PI3K/Akt signaling pathway, which provides new insights into the underlying molecular mechanisms of drug resistance to EGFR-TKIs in NSCLC. In addition, our study sheds light on developing novel therapeutic approaches to overcome EGFR-TKI resistance in NSCLC.