The Emerging Role of p27 in Development of Diseases

MiRNA-related metastasis in oral cancer: moving and shaking

Across the world, oral cancer is a prevalent tumor. Over the years, both its mortality and incidence have grown. Oral cancer metastasis is a complex process involving cell invasion, migration, proliferation, and egress from cancer tissue either by lymphatic vessels or blood vessels. MicroRNAs (miRNAs) are essential short non-coding RNAs, which can act either as tumor suppressors or as oncogenes to control cancer development. Cancer metastasis is a multi-step process, in which miRNAs can inhibit or stimulate metastasis at all stages, including epithelial-mesenchymal transition, migration, invasion, and colonization, by targeting critical genes in these pathways. On the other hand, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), two different types of non-coding RNAs, can regulate cancer metastasis by affecting gene expression through cross-talk with miRNAs. We reviewed the scientific literature (Google Scholar, Scopus, and PubMed) for the period 2000-2023 to find reports concerning miRNAs and lncRNA/circRNA-miRNA-mRNA networks, which control the spread of oral cancer cells by affecting invasion, migration, and metastasis. According to these reports, miRNAs are involved in the regulation of metastasis pathways either by directly or indirectly targeting genes associated with metastasis. Moreover, circRNAs and lncRNAs can induce or suppress oral cancer metastasis by acting as competing endogenous RNAs to inhibit the effect of miRNA suppression on specific mRNAs. Overall, non-coding RNAs (especially miRNAs) could help to create innovative therapeutic methods for the control of oral cancer metastases.

NEDD4L inhibits glycolysis and proliferation of cancer cells in oral squamous cell carcinoma by inducing ENO1 ubiquitination and degradation

Glycolysis contributes to cell metabolism and facilitates cell proliferation of oral squamous cell carcinoma (OSCC), the most common type of oral cancer. Understanding the regulatory mechanisms involved in the glycolysis of OSCC cells may provide important therapeutic inspirations. Immunohistochemistry was used to examine protein localization patterns in human OSCC tissues and Western blot was conducted to gauge protein level. Lentivirus transduction was used to overexpress or silence genes of interest. Cell proliferation was assessed by Cell Counting Kit (CCK)-8 assay while glycolysis was examined via measurement of extracellular acidification rate, oxygen consumption rate, and lactate and ATP production. In vivo cancer development was evaluated with a mouse tumor growth model. OSCC tissues displayed reduced expression of NEDD4L compared with normal tissues. NEDD4L expression positively correlated with 5-year patient survival rate, indicating that NEDD4L may be a prognosis marker for OSCC. NEDD4L overexpression suppressed proliferation, cell cycle transition, and glycolysis in OSCC cells, and inhibited in vivo tumor growth. UbiBrowser identified ENO1, an enzyme that catalyzes glycolysis, as a substrate of NEDD4L. Overexpression of NEDD4L resulted in the ubiquitination and subsequent degradation of ENO1 whereas overexpression of ENO1 reversed the functional effects of NEDD4L overexpression, restoring proliferation, cell cycle transition, and glycolysis in OSCC cells. NEDD4L elicits tumor-suppressive functions via inhibition of OSCC cell proliferation, cell cycle transition, and glycolysis by stimulating ENO1 ubiquitination and degradation. Our results unraveled a signaling axis important for OSCC cell survival and metabolism, which can serve as a potential therapeutic target.

Cell size, body size and Peto's paradox

Carcinogenesis is one of the leading health concerns afflicting presumably every single animal species, including humans. Currently, cancer research expands considerably beyond medicine, becoming a focus in other branches of natural science. Accumulating evidence suggests that a proportional scale of tumor deaths involves domestic and wild animals and poses economical or conservation threats to many species. Therefore, understanding the genetic and physiological mechanisms of cancer initiation and its progression is essential for our future action and contingent prevention. From this perspective, I used an evolutionary-based approach to re-evaluate the baseline for debate around Peto's paradox. First, I review the background of information on which current understanding of Peto's paradox and evolutionary concept of carcinogenesis have been founded. The weak points and limitations of theoretical modeling or indirect reasoning in studies based on intraspecific, comparative studies of carcinogenesis are highlighted. This is then followed by detail discussion of an effect of the body mass in cancer research and the importance of cell size in consideration of body architecture; also, I note to the ambiguity around cell size invariance hypothesis and hard data for variability of cell size across species are provided. Finally, I point to the new research area that is driving concepts to identify exact molecular mechanisms promoting the process of tumorigenesis, which in turn may provide a proximate explanation of Peto's paradox. The novelty of the approach proposed therein lies in intraspecies testing of the effect of differentiation of cell size/number on the probability of carcinogenesis while controlling for the confounding effect of body mass/size.

The modulation of PI3K/Akt pathway by 3β hydroxylup-12-en-28-oic acid isolated from Thymus linearis induces cell death in HCT-116 cells

The presence of intricate carbon skeletons in natural compounds enhances their bioactivity spectrum with unique modes of action at several targets in various dreadful diseases like cancer. The present study was designed to purify the molecules from Thymus linearis and elucidate their antiproliferative activity. The compounds were isolated from the active methanolic extract of Thymus linearis through column chromatography and characterized by various spectroscopic techniques. Antiproliferative activity of isolated compounds was evaluated using MTT assay on cancer and normal cell lines. Mechanism of cell death was elucidated using flow cytometric, microscopic, and Western blot analysis. Four compounds, Sitosterol, Chrysin, 3β-hydroxylup-12-en-28-oic acid (3BH), and β-Sitosterol glycoside, were isolated. Among these, 3BH was most potent antiproliferative agent across all cell lines under study, HCT-116 being the most affected one. 3BH was demonstrated to downregulate PI3Ksubunits (p110α and p85α), downstream pAktSer⁴⁷³ and prompted G₁ phase cell cycle arrest. The cell cycle CDK inhibitor p27 and p21 were upregulated with simultaneous downregulation of cyclin D1 and cyclin E in HCT-116 cells. This was accompanied by apoptosis, as depicted by decrease in Bcl-2/Bax ratio, with increase in active caspases-3 and caspase-9, cleavage of PARP-1, the generation of reactive oxygen species (ROS), and the loss of mitochondrial membrane potential. The findings established that 3BH induced cell death in HCT-116 cells by modulating PI3K/Akt signaling axis, impeding cell cycle, and instigating apoptosis.

Cyclin-dependent kinase inhibitor 1B acts as a novel molecule to mediate testosterone synthesis and secretion in mouse Leydig cells by luteinizing hormone (LH) signaling pathway

Cyclin-dependent kinase inhibitor 1B (Cdkn1b, p27) plays important regulatory roles in many cellular processes. p27 is highly expressed in the mouse testis, but its roles and underlying mechanisms for testosterone synthesis and secretion remain not well understood. In the current study, we found that p27 located in Leydig cells and Sertoli cells of adult mouse testis. To explore the function of p27 in Leydig cells, p27 inhibitor and activator were injected into the adult mice, primary Leydig cells and TM3 cells. Our in vivo and in vitro results showed that change in the expression of p27 significantly alters the testosterone in both globe serum and culture medium. Meanwhile, the steroidogenesis-related gene expression was significantly regulated too. Moreover, our in vitro study showed that luteinizing hormone (LH) significantly increased p27 mRNA levels. Furthermore, our results proved that altering the mRNA expression of p27 leads to the synchronized changes of Lhcgr, Star, Cyp11a1, Hsd3b6, Cyp11a1, and Hsd17b3. Alterations of p27 also result in synchronously changes of RAF1 and ERK1/2 phosphorylation. These findings indicate that p27 plays vital roles in LH-induced testosterone production, providing a novel mechanism that p27 acts as an upstream molecule to elevate ERK1/2 phosphorylation to promote the expression of StAR and other cholesterol-metabolizing enzymes.

Lupus susceptibility region containing CDKN1B rs34330 mechanistically influences expression and function of multiple target genes, also linked to proliferation and apoptosis

OBJECTIVE

A recent genome-wide association study (GWAS) reported a significant genetic association between rs34330 of cyclin-dependent kinase inhibitor 1B (CDKN1B) and risk of systemic lupus erythematosus (SLE) in Han Chinese. This study aims to validate the reported association and elucidate the biochemical mechanisms underlying the variant's effect.

METHODS

We performed allelic association with SLE followed by meta-analysis across 11 independent cohorts (n=28,872). We applied in silico bioinformatics and experimental validation in SLE-relevant cell lines to determine the functional consequences of rs34330.

RESULTS

We replicated genetic association between SLE and rs34330 (P_meta =5.29x10^-22 , OR (95% CI)=0.84 (0.81-0.87)). Follow-up bioinformatics and eQTL analysis suggest that rs34330 is located in active chromatin and potentially regulates several target genes. Using luciferase and ChIP-qPCR, we demonstrated substantial allele-specific promoter and enhancer activity, and allele-specific binding of three histone marks (H3K27ac, H3K4me3, H3K4me1), RNA pol II, CTCF, and a critical immune transcription factor (IRF-1). Chromosome conformation capture (3C) detected long-range chromatin interactions between rs34330 and the promoters of neighboring genes APOLD1 and DDX47, and effects on CDKN1B and the other target genes were directly validated by CRISPR-based genome editing. Finally, CRISPR-dCas9-based epigenetic activation/silencing confirmed these results. Gene-edited cell lines also showed higher levels of proliferation and apoptosis.

CONCLUSION

Collectively, these findings suggest a mechanism whereby the rs34330 risk allele (C) influences the presence of histone marks, RNA pol II, and the IRF-1 transcription factor to regulate expression of several target genes linked to proliferation and apoptosis, which potentially underlie the association of rs34330 with SLE.

A SOX2 Reporter System Identifies Gastric Cancer Stem-Like Cells Sensitive to Monensin

Gastric cancer remains a serious health burden with few therapeutic options. Therefore, the recognition of cancer stem cells (CSCs) as seeds of the tumorigenic process makes them a prime therapeutic target. Knowing that the transcription factors SOX2 and OCT4 promote stemness, our approach was to isolate stem-like cells in human gastric cancer cell lines using a traceable reporter system based on SOX2/OCT4 activity (SORE6-GFP). Cells transduced with the SORE6-GFP reporter system were sorted into SORE6+ and SORE6- cell populations, and their biological behavior characterized. SORE6+ cells were enriched for SOX2 and exhibited CSC features, including a greater ability to proliferate and form gastrospheres in non-adherent conditions, a larger in vivo tumor initiating capability, and increased resistance to 5-fluorouracil (5-FU) treatment. The overexpression and knockdown of SOX2 revealed a crucial role of SOX2 in cell proliferation and drug resistance. By combining the reporter system with a high-throughput screening of pharmacologically active small molecules we identified monensin, an ionophore antibiotic, displaying selective toxicity to SORE6+ cells. The ability of SORE6-GFP reporter system to recognize cancer stem-like cells facilitates our understanding of gastric CSC biology and serves as a platform for the identification of powerful therapeutics for targeting gastric CSCs.

Long noncoding RNA GAS5 impairs the proliferation and invasion of endometrial carcinoma induced by high glucose via targeting miR-222-3p/p27

Long noncoding RNAs (lncRNAs) have been identified to be critical functional regulator in the human tumors, while the deepgoing mechanism by which lncRNAs modulates the endometrial carcinoma is still elusive. In this work, we found that lncRNA GAS5 was under-expressed in the endometrial carcinoma tissue specimens, especially these samples with type 2 diabetes mellitus. Besides, the aberrant under-expression of GAS5 was correlated with the advanced tumor stage as well as poor prognosis outcome. In cellular experiments, GAS5 was decreased in the cells exposed to the high glucose. Enforced GAS5 expression repressed the tumor phenotype of endometrial carcinoma cells, including proliferation and invasion. Molecular mechanism study further demonstrated that GAS5 functioned as a sponge for miR-222-3p, abrogating its ability of inhibiting p27 protein expression. In conclusion, these results confirmed the vital regulation of GAS5/miR-222-3p/p27 axis in the endometrial carcinoma tumorigenesis.