Phosphorylation of OCT4 Serine 236 Inhibits Germ Cell Tumor Growth by Inducing Differentiation

DNA methylation of POU5F1 by DNMT1 and DNMT3B triggers apoptosis in interstitial Cajal-like cells via c-kit/SCF inhibition during cholesterol gallstone formation

We have previously reported that inactivation of c-kit and stem cell factor (SCF) might reduce interstitial Cajal-like cells (ICLCs) density, leading to gallbladder motility impairment and cholesterol gallstone (CG) formation. Based on bioinformatics prediction, this study explores the possible role of POU class 5 homeobox 1 (POU5F1) in c-kit/SCF regulation and investigates their function in ICLC activity and CG development. POU5F1 was identified as a transcription factor targeting both c-kit and SCF for transcription activation. They were poorly expressed in mice fed a lithogenic diet (LD) and mouse ICLCs treated with cholesterol. Upregulation of POU5F1 alleviated ICLC apoptosis, contraction dysfunction, and CG formation in the gallbladder wall of mice. Similarly, the POU5F1 upregulation enhanced the viability of ICLCs in vitro while reducing cell apoptosis. However, these effects were blocked by either c-kit or SCF knockdown. Furthermore, DNA methyltransferase 1 (DNMT1) and DNMT3B were identified as two important regulators suppressing POU5F1 transcription through DNA methylation. Knockdown of either DNMT1 or DNMT3B restored POU5F1 and c-kit/SCF levels, therefore reducing ICLC apoptosis and CG formation. In conclusion, this study demonstrates that DNMT1/DNMT3B-mediated DNA methylation of POU5F1 induces c-kit/SCF downregulation, thus promoting apoptosis of ICLCs and CG formation.

SOX2 Expression Does Not Guarantee Cancer Stem Cell-like Characteristics in Lung Adenocarcinoma

Effectively targeting cancer stemness is essential for successful cancer therapy. Recent studies have revealed that SOX2, a pluripotent stem cell factor, significantly contributes to cancer stem cell (CSC)-like characteristics closely associated with cancer malignancy. However, its contradictory impact on patient survival in specific cancer types, including lung adenocarcinoma (LUAD), underscores the need for more comprehensive research to clarify its functional effect on cancer stemness. In this study, we demonstrate that SOX2 is not universally required for the regulation of CSC-like properties in LUAD. We generated SOX2 knockouts in A549, H358, and HCC827 LUAD cells using the CRISPR/Cas9 system. Our results reveal unchanged CSC characteristics, including sustained proliferation, tumor sphere formation, invasion, migration, and therapy resistance, compared to normal cells. Conversely, SOX2 knockdown using conditional shRNA targeting SOX2, significantly reduced CSC traits. However, these loss-of-function effects were not rescued by SOX2 resistant to shRNA, underscoring the potential for SOX2 protein level-independent results in prior siRNA- or shRNA-based research. Ultimately, our findings demonstrate that SOX2 is not absolutely essential in LUAD cancer cells. This emphasizes the necessity of considering cancer subtype-dependent and context-dependent factors when targeting SOX2 overexpression as a potential therapeutic vulnerability in diverse cancers.

Crosstalk between Noncoding RNAs and the Epigenetics Machinery in Pediatric Tumors and Their Microenvironment

According to the World Health Organization, every year, an estimated 400,000+ new cancer cases affect children under the age of 20 worldwide. Unlike adult cancers, pediatric cancers develop very early in life due to alterations in signaling pathways that regulate embryonic development, and environmental factors do not contribute much to cancer development. The highly organized complex microenvironment controlled by synchronized gene expression patterns plays an essential role in the embryonic stages of development. Dysregulated development can lead to tumor initiation and growth. The low mutational burden in pediatric tumors suggests the predominant role of epigenetic changes in driving the cancer phenotype. However, one more upstream layer of regulation driven by ncRNAs regulates gene expression and signaling pathways involved in the development. Deregulation of ncRNAs can alter the epigenetic machinery of a cell, affecting the transcription and translation profiles of gene regulatory networks required for cellular proliferation and differentiation during embryonic development. Therefore, it is essential to understand the role of ncRNAs in pediatric tumor development to accelerate translational research to discover new treatments for childhood cancers. This review focuses on the role of ncRNA in regulating the epigenetics of pediatric tumors and their tumor microenvironment, the impact of their deregulation on driving pediatric tumor progress, and their potential as effective therapeutic targets.

Circ_0061395 functions as an oncogenic gene in hepatocellular carcinoma by acting as a miR-1182 sponge

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in liver cancer, with a high rate of metastasis and recurrence. Circular RNA_0061395 (circ_0061395) has been shown to be involved in the advance of HCC. However, the interaction between circ_0061395 and microRNA (miRNA) in HCC has not been studied. Quantitative real-time polymerase-chain reaction (qRT-PCR) was used to detect the expression of related genes in liver cancer tissues and cells. The stability of circ_0061395 was verified by RNase R digestion. Through detection of cell malignant behavior and apoptosis, the capping experiment was carried out to verify the regulatory relationship between miR-1182 and circ_0061395 or SPARC/osteonectin, CWCV and Kazal-like domains proteoglycan 1 (SPOCK1). The expression of related proteins was detected by western blot. The interaction of miR-1182 with circ_0061395 or SPOCK1 has been notarized by Dual-luciferase reporter analysis and RNA immunoprecipitation (RIP) assay. Xenotransplantation experiments using BALB/C nude mice were used to confirm the function of circ_0061395 in vivo. Circ_0061395 and SPOCK1 were significantly expressed in liver cancer tissues and cells. Silencing circ_0061395 reduced the proliferation, migration, invasion, tube formation and tumor spheroid formation rate of Huh-7 and SNU-387 cells. MiR-1182 was a target of circ_0061395. Silencing circ_0061395 inhibited the malignant behavior of HCC cells by releasing miR-1182. In addition, SPOCK1 was the target of miR-1182. Overexpression of SPOCK1 partially restored the inhibitory effect of miR-1182 on cell proliferation. Animal experiments confirmed the anti-tumor effect of silence circ_0061395. Circ_0061395 induced the changes of the expression of SPOCK1 by regulating miR-1182, thereby mediating the process of HCC, and at least partially promoting the development of HCC cells, providing a novel targeted therapy for HCC.

The expression of circ_0090049 in hepatocellular carcinoma and the molecular regulation mechanism of other biological functions

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors in liver cancer. Circular RNA_0090049 (circ_0090049) has been shown to be involved in the advance of HCC. However, the interaction between circ_0090049 and microRNA (miRNA) in HCC has not been studied. Quantitative real-time PCR was used to detect the expression of related genes. Through detection of cell proliferation, migration, invasion, and rate of tumor sphere formation, the capping experiment was carried out to verify the regulatory relationship between miRNA and circ_0090049 or circ_0090049 and ubiquitin-conjugating enzyme E2 T (UBE2T). The expression of related proteins was detected by Western blotting. The interaction of miRNA with circ_0090049 or UBE2T was notarized by Dual-luciferase reporter assay. Xenotransplantation experiments confirmed the function of circ_0090049 in vivo. Circ_0090049 and UBE2T were upregulated in liver cancer. Silencing circ_0090049 reduced the proliferation, migration, invasion, and tumor spheroid formation rate of Huh7 and HCCLM3 cells. MiR-605-5p and miR-548c-3p were identified as targets of circ_0090049, and UBE2T was the target of miR-605-5p and miR-548c-3p. Anti-miR-605-5p, anti-miR-548c-3p or UBE2T overexpression restored the inhibitory effect of circ_0090049 knockdown on HCC cells. Animal experiments confirmed the antitumor effect of silence circ_0090049. Circ_0090049 regulates the expression of UBE2T by regulating miR-605-5p or miR-548c-3p, thereby promoting the development of HCC cells.

O-GlcNAcylation of Sox2 at threonine 258 regulates the self-renewal and early cell fate of embryonic stem cells

Sox2 is a core transcription factor in embryonic stem cells (ESCs), and O-GlcNAcylation is a type of post-translational modification of nuclear-cytoplasmic proteins. Although both factors play important roles in the maintenance and differentiation of ESCs and the serine 248 (S248) and threonine 258 (T258) residues of Sox2 are modified by O-GlcNAcylation, the function of Sox2 O-GlcNAcylation is unclear. Here, we show that O-GlcNAcylation of Sox2 at T258 regulates mouse ESC self-renewal and early cell fate. ESCs in which wild-type Sox2 was replaced with the Sox2 T258A mutant exhibited reduced self-renewal, whereas ESCs with the Sox2 S248A point mutation did not. ESCs with the Sox2 T258A mutation heterologously introduced using the CRISPR/Cas9 system, designated E14-Sox2^TA/WT, also exhibited reduced self-renewal. RNA sequencing analysis under self-renewal conditions showed that upregulated expression of early differentiation genes, rather than a downregulated expression of self-renewal genes, was responsible for the reduced self-renewal of E14-Sox2^TA/WT cells. There was a significant decrease in ectodermal tissue and a marked increase in cartilage tissue in E14-Sox2^TA/WT-derived teratomas compared with normal E14 ESC-derived teratomas. RNA sequencing of teratomas revealed that genes related to brain development had generally downregulated expression in the E14-Sox2^TA/WT-derived teratomas. Our findings using the Sox2 T258A mutant suggest that Sox2 T258 O-GlcNAc has a positive effect on ESC self-renewal and plays an important role in the proper development of ectodermal lineage cells. Overall, our study directly links O-GlcNAcylation and early cell fate decisions.

SEZ6L2 Is an Important Regulator of Drug-Resistant Cells and Tumor Spheroid Cells in Lung Adenocarcinoma

Many lung cancer deaths result from relapses in distant organs, such as the brain or bones, after standard chemotherapy. For cancer cells to spread to other organs, they must survive as circulating tumor cells (CTCs) in blood vessels. Thus, reducing distant recurrence after chemotherapy requires simultaneously inhibiting drug resistance and CTC survival. Here, we investigated the molecular pathways and genes that are commonly altered in drug-resistant lung cancer cells and lung tumor spheroid (TS) cells. First, RNA sequencing was performed in drug-resistant cells and TS cells originating from H460 and A549 lung cancer cells. Bioinformatic pathway analysis showed that cell cycle-related pathways were downregulated in drug-resistant cells, and cholesterol biosynthesis-related pathways were upregulated in TS cells. Seizure-related 6 homolog-like 2 (SEZ6L2) was selected as a gene that was commonly upregulated in both drug-resistant cells and TS cells, and that showed elevated expression in samples from lung adenocarcinoma patients. Second, the protein expression of SEZ6L2 was analyzed by flow cytometry. The proportions of SEZ6L2 positive cells among both drug-resistant cells and TS cells was increased. Finally, as SEZ6L2 is a transmembrane protein with an extracellular region, the function of SEZ6L2 was disrupted by treatment with an anti-SEZ6L2 antibody. Treatment with the anti-SEZ6L2 antibody reduced drug resistance and TS formation. Overall, our data showed that SEZ6L2 plays an important role in drug resistance and TS formation and may be a therapeutic target for reducing distant recurrence of lung adenocarcinoma.