Cervical cancer (CC) stem cell-like cells (CCSLCs), defined by the capacity of differentiation and self-renewal and proliferation, play a significant role in the progression of CC. However, the molecular mechanisms regulating their self-renewal are poorly understood. Therefore, elucidation of the epigenetic mechanisms that drive cancer stem cell self-renewal will enhance our ability to improve the effectiveness of targeted therapies for cancer stem cells.

To explore how DNA methyltransferase 1 (DNMT1)/miR-342-3p/Forkhead box M1 (FoxM1), which have been shown to have abnormal expression in CCSLCs, and their signaling pathways could stimulate self-renewal-related stemness in CCSLCs.

Sphere-forming cells derived from CC cell lines HeLa, SiHa and CaSki served as CCSLCs. Self-renewal-related stemness was identified by determining sphere and colony formation efficiency, CD133 and CD49f protein level, and SRY-box transcription factor 2 and octamer-binding transcription factor 4 mRNA level. The microRNA expression profiles between HeLa cells and HeLa-derived CCSLCs or mRNA expression profiles that HeLa-derived CCSLCs were transfected with or without miR-342-3p mimic were compared using quantitative PCR analysis. The expression levels of DNMT1 mRNA, miR-342-3p, and FoxM1 protein were examined by quantitative real-time PCR and western blotting. In vivo carcinogenicity was assessed using a mouse xenograft model. The functional effects of the DNMT1/miR-342-3p/FoxM1 axis were examined by in vivo and in vitro gain-of-activity and loss-of-activity assessments. Interplay among DNMT1, miR-342-3p, and FoxM1 was tested by methylation-specific PCR and a respective luciferase reporter assay.

CCSLCs derived from the established HeLa cell lines displayed higher self-renewal-related stemness, including enhanced sphere and colony formation efficiency, increased CD133 and CD49f protein level, and heightened transcriptional quantity of stemness-related factors SRY-box transcription factor 2 and octamer-binding transcription factor 4 in vitro as well as a stronger tumorigenic potential in vivo compared to their parental cells. Moreover, quantitative PCR showed that the miR-342-3p level was downregulated in HeLa-derived CCSLCs compared to HeLa cells. Its mimic significantly decreased DNMT1 and FoxM1 mRNA expression levels in CCSLCs. Knockdown of DNMT1 or miR-342-3p mimic transfection suppressed DNMT1 expression, increased miR-342-3p quantity by promoter demethylation, and inhibited CCSLC self-renewal. Inhibition of FoxM1 by shRNA transfection also resulted in the attenuation of CCSLC self-renewal but had little effect on the DNMT1 activity and miR-342-3p expression. Furthermore, the loss of CCSLC self-renewal exerted by miR-342-3p mimic was inverted by the overexpression of DNMT1 or FoxM1. Furthermore, DNMT1 and FoxM1 were recognized as straight targets by miR-342-3p in HeLa-derived CCSLCs.

Our findings suggested that a novel DNMT1/miR-342-3p/FoxM1 signal axis promotes CCSLC self-renewal and presented a potential target for the treatment of CC through suppression of CCSLC self-renewal. However, this pathway has been previously implicated in CC, as evidenced by prior studies showing miR-342-3p-mediated downregulation of FoxM1 in cervical cancer cells. Additionally, research on liver cancer further supports the involvement of miR-342-3p in suppressing FoxM1 expression. While our study contributed to this body of knowledge, we did not present a completely novel axis but reinforced the therapeutic potential of targeting the DNMT1/miR-342-3p/FoxM1 axis to suppress CCSLC self-renewal in CC treatment.

Hepatocellular carcinoma (HCC) is among the most malignant tumors and seriously threatens human health worldwide, and its incidence rate is increasing annually. USP15 is a member of the ubiquitination-specific protease (USP) family, which can regulate protein ubiquitination, thereby affecting their stability, and is dysregulated in many cancers, but its expression and regulatory mechanism in HCC are unclear. The aims of this study were to explore the role and mechanism of USP15 in regulating HCC cell stemness, proliferation, and lenvatinib resistance. Immunohistochemistry and high-throughput sequencing analyses of tumor and adjacent normal tissue samples from 52 patients with HCC were conducted. Functional analyses of immortalized human liver and HCC cell lines were conducted, including quantitative real-time PCR; western blot; plasmid, lentivirus, and siRNA transfection; co-immunoprecipitation; mass spectrometry; MeRIP-qPCR; and ubiquitination, cell growth, colony formation, and spheroid formation assays. HCC tumor growth was also assessed using cell transplantation in nude mice. We found that USP15 is upregulated in HCC and affects patient prognosis. Our results demonstrated that USP15 can increase LGALS3 stability in HCC through deubiquitination modification, and affect the stemness, proliferation, and lenvatinib resistance of HCC cells by activating the AKT/mTOR pathway. USP15 expression levels were positively correlated with HCC cell stemness, proliferation, and lenvatinib resistance. In addition, methyltransferase-like protein 3 (Mettl3) N6-methyladenosine (m6A) modified USP15 to upregulate its levels by increasing its mRNA stability. These findings provide a theoretical basis for the potential discovery of new HCC oncogenes, as well as the identification of effective targets and development of novel anti-HCC drugs and clinical applications.

As a hallmark of cancer, metabolic reprogramming adjusts macromolecular synthesis, energy metabolism and redox homeostasis processes to adapt to and promote the complex biological processes of abnormal growth and proliferation. The complexity of metabolic reprogramming lies in its precise regulation by multiple levels and factors, including the interplay of multiple signalling pathways, precise regulation of transcription factors and dynamic adjustments in metabolic enzyme activity. In this complex regulatory network, acetylation and deacetylation, which are important post-translational modifications, regulate key molecules and processes related to metabolic reprogramming by affecting protein function and stability. Dysregulation of acetylation and deacetylation may alter cancer cell metabolic patterns by affecting signalling pathways, transcription factors and metabolic enzyme activity related to metabolic reprogramming, increasing the susceptibility to rapid proliferation and survival. In this review, we focus on discussing how acetylation and deacetylation regulate cancer metabolism, thereby highlighting the central role of these post-translational modifications in metabolic reprogramming, and hoping to provide strong support for the development of novel cancer treatment strategies. KEY POINTS: Protein acetylation and deacetylation are key regulators of metabolic reprogramming in tumour cells. These modifications influence signalling pathways critical for tumour metabolism. They modulate the activity of transcription factors that drive gene expression changes. Metabolic enzymes are also affected, altering cellular metabolism to support tumour growth.

Liver cancer stem cell (CSC) self-renewal and tumorigenesis are important causes of hepatocellular carcinoma (HCC) recurrence. We purposed to investigate the function of long noncoding RNA small nucleolar RNA host gene 9 (SNHG9) in liver CSC self-renewal and tumorigenesis in this study. Flow cytometry was carried out to separate CD133+ Populations and CD133- Populations from HCC cell lines. A combination of CD133+ cells and Matrigel matrix was subcutaneously injected to create the NOD-SCID mouse xenograft tumor model. Colony formation test and spheroids formation assay were carried out to clarify the impact of SNHG9 on the self-renewal of liver CSCs. RNA immunoprecipitation, RNA-pull down, and chromatin immunoprecipitation were performed on CD133+ cells to elucidate the mechanism of SNHG9 regulating PTEN expression. We found that SNHG9 was highly expressed in HCC clinical samples, HCC cells, and CD133+ cells. In vitro, interference with SNHG9 prevented the formation of colonies and spheroids in liver CSC cells and primary HCC cells. In vivo, interference with SNHG9 reduced the tumor volume and weight. SNHG9 could bind to EZH2, and SNHG9 interference suppressed EZH2 recruitment and H3K27me3 levels in the PTEN promoter region. In addition, SNHG9 inhibition promoted PTEN expression while having little impact on EZH2 levels. Interference with SNHG9 inhibited liver CSC self-renewal and tumorigenesis by up-regulating PTEN levels. In conclusion, by binding to EZH2, SNHG9 down-regulated PTEN levels, promoting liver CSC self-renewal and tumor formation, and exacerbating HCC progression.

Tendon-derived stem cells (TDSCs) are proposed as a potential cell-seed for the treatment of tendon injury due to their tenogenic differentiation potential. In this work, we defined the action of long non-coding RNA (lncRNA) muscle differentiation 1 (LINCMD1) in tenogenic differentiation of human TDSCs (hTDSCs).

Quantitative real-time PCR (qRT-PCR) was used to assess the levels of LINCMD1, microRNA (miR)-342-3p, and early growth response-1 (EGR1) mRNA. Cell proliferation was detected by the XTT colorimetric assay. Protein expression was quantified by western blot. hTDSCs were grown in an osteogenic medium to induce osteogenic differentiation, and the extent of osteogenic differentiation was assessed by Alizarin Red Staining (ARS). The activity of alkaline phosphatase (ALP) was measured by the ALP Activity Assay Kit. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to evaluate the direct relationship between miR-342-3p and LINCMD1 or EGR1.

Our results showed that enforced expression of LINCMD1 or suppression of miR-342-3p accelerated the proliferation and tenogenic differentiation and reduced osteogenic differentiation of hTDSCs. LINCMD1 regulated miR-342-3p expression by binding to miR-342-3p. EGR1 was identified as a direct and functional target of miR-342-3p, and knockdown of EGR1 reversed the effects of miR-342-3p suppression on cell proliferation and tenogenic and osteogenic differentiation. Furthermore, the miR-342-3p/EGR1 axis mediated the regulation of LINCMD1 on hTDSC proliferation and tenogenic and osteogenic differentiation.

Our study suggests the induction of LINCMD1 in tenogenic differentiation of hTDSCs through miR-342-3p/EGR1 axis.

Deregulation of protein post-translational modifications is intensively involved in the etiology of diseases, including degenerative diseases, inflammatory injuries, and cancers. Acetylation is one of the most common post-translational modifications of proteins, and the acetylation levels are controlled by two mutually antagonistic enzyme families, histone acetyl transferases (HATs) and histone deacetylases (HDACs). HATs loosen the chromatin structure by neutralizing the positive charge of lysine residues of histones; whereas HDACs deacetylate certain histones, thus inhibiting gene transcription. Compared with HATs, HDACs have been more intensively studied, particularly regarding their clinical significance. HDACs extensively participate in the regulation of proliferation, migration, angiogenesis, immune escape, and therapeutic resistance of cancer cells, thus emerging as critical targets for clinical cancer therapy. Compared to HATs, inhibitors of HDAC have been clinically used for cancer treatment. Here, we enumerate and integratethe mechanisms of HDAC family members in tumorigenesis and cancer progression, and address the new and exciting therapeutic implications of single or combined HDAC inhibitor (HDACi) treatment.