TSPAN12 is overexpressed in NSCLC via p53 inhibition and promotes NSCLC cell growth in vitro and in vivo

The versatile roles of testrapanins in cancer from intracellular signaling to cell-cell communication: cell membrane proteins without ligands

The tetraspanins (TSPANs) are a family of four-transmembrane proteins with 33 members in mammals. They are variably expressed on the cell surface, various intracellular organelles and vesicles in nearly all cell types. Different from the majority of cell membrane proteins, TSPANs do not have natural ligands. TSPANs typically organize laterally with other membrane proteins to form tetraspanin-enriched microdomains (TEMs) to influence cell adhesion, migration, invasion, survival and induce downstream signaling. Emerging evidence shows that TSPANs can regulate not only cancer cell growth, metastasis, stemness, drug resistance, but also biogenesis of extracellular vesicles (exosomes and migrasomes), and immunomicroenvironment. This review summarizes recent studies that have shown the versatile function of TSPANs in cancer development and progression, or the molecular mechanism of TSPANs. These findings support the potential of TSPANs as novel therapeutic targets against cancer.

SOX2-positive retinal stem cells are identified in adult human pars plicata by single-cell transcriptomic analyses

Stem cell therapy is a promising strategy to rescue visual impairment caused by retinal degeneration. Previous studies have proposed controversial theories about whether in situ retinal stem cells (RSCs) are present in adult human eye tissue. Single-cell RNA sequencing (scRNA-seq) has emerged as one of the most powerful tools to reveal the heterogeneity of tissue cells. By using scRNA-seq, we explored the cell heterogeneity of different subregions of adult human eyes, including pars plicata, pars plana, retinal pigment epithelium (RPE), iris, and neural retina (NR). We identified one subpopulation expressing SRY-box transcription factor 2 (SOX2) as RSCs, which were present in the pars plicata of the adult human eye. Further analysis showed the identified subpopulation of RSCs expressed specific markers aquaporin 1 (AQP1) and tetraspanin 12 (TSPAN12). We, therefore, isolated this subpopulation using these two markers by flow sorting and found that the isolated RSCs could proliferate and differentiate into some retinal cell types, including photoreceptors, neurons, RPE cells, microglia, astrocytes, horizontal cells, bipolar cells, and ganglion cells; whereas, AQP1- TSPAN12- cells did not have this differentiation potential. In conclusion, our results showed that SOX2-positive RSCs are present in the pars plicata and may be valuable for treating human retinal diseases due to their proliferation and differentiation potential.

Identification of RHEX as a novel biomarker related to progression and immunity of non-small cell lung carcinoma

Background

The therapeutic response and prognosis of patients with non-small cell lung carcinoma (NSCLC) are widely related to immunity. To improve the prognosis of patients and provide reliable information to guide appropriate personalized treatment strategies, it is necessary to identify reliable prognostic or predictive indicators closely related to tumor phenotype and immune traits in NSCLC.

Methods

Based on The Cancer Genome Atlas (TCGA)-NSCLC mRNA expression profile data, a novel approach combining differential gene expression analysis, single-sample gene set enrichment analysis (ssGSEA), and weighted gene co-expression network analysis (WGCNA) was used to screen hub genes. Subsequently, the regulator of hemoglobinization and erythroid cell expansion (RHEX) was identified as a key gene using the log-rank test and confirmed in the ArrayExpress database. The relationship between RHEX and clinicopathological parameters was analyzed using the Wilcoxon rank-sum test. More importantly, through gene set enrichment analysis (GSEA) and cell-type identification by estimating relative subsets of RNA transcripts (CIBERSORT) algorithms, and with reference to the Tumor IMmune Estimation Resource (TIMER) database, we explored the relevant pathways of RHEX and its relationship with tumor-infiltrating immune cells (TICs). Finally, we depicted the association between RHEX and immunomodulators in the TCGA and a web portal TISIDB.

Results

The RHEX mRNA expression levels in tumor tissues were lower than those in normal tissues and declined with the progression of NSCLC. Meanwhile, RHEX overexpression was associated with high immune infiltration levels and a favorable clinical prognosis. RHEX may participate in tumor microenvironment (TME) regulation through multiple tumor-immune related pathways, especially the JAK-STAT signaling pathway. Furthermore, RHEX expression affected the infiltrating abundance of multiple TICs and positively correlated with most of the immunomodulators in NSCLC.

Conclusions

Our study is the first to propose that RHEX is an immune-related gene with prognostic value in NSCLC and reveals the underlying mechanism between RHEX and tumor-immune system interactions. These results ultimately provide guidance for prognosis and immunotherapy for NSCLC patients.

m5C RNA Methylation Regulators Predict Prognosis and Regulate the Immune Microenvironment in Lung Squamous Cell Carcinoma

RNA methylation is a novel epigenetic modification that can be used to evaluate tumor prognosis. However, the underlying mechanisms are unclear. This study aimed to investigate the genetic characteristics of 5-methylcytosine (m5C) and N1-methyladenosine (m1A) regulators in lung squamous cell carcinoma (LUSC) and the prognostic value and immune-related effects of m5C regulators. To this end, we selected the public LUSC dataset from the Cancer Genome Atlas and Gene Expression Omnibus. The least absolute shrinkage and selection operator regression model was used to identify prognostic risk signatures. We used the UALCAN and Human Protein Atlas databases to study the expression of target gene mRNA/protein expression. Furthermore, the Tumor Immune Single Cell Hub and the Tumor Immune Estimation Resource were used to evaluate the degree of immune cell infiltration. Most of the m5C and m1A regulators showed significantly different expression between LUSC and normal samples. The m5C regulators were associated with poor prognosis. In addition, a prognostic risk signature was developed based on two m5C regulators, NOP2/Sun RNA methyltransferase 3 (NSUN3), and NOP2/Sun RNA methyltransferase 4 (NSUN4). Compared with normal lung tissues, the expression of NSUN3 and NSUN4 in the LUSC TCGA dataset was increased, which was related to clinicopathological characteristics and survival. NSUN3 and NSUN4 were related to the infiltration of six major immune cells; especially NSUN3, which was closely related to CD8+ T cells, while NSUN4 was closely related to neutrophils. Our findings suggest that m5C regulators can predict the clinical prognosis risk and regulate the tumor immune microenvironment in LUSC.

Ring finger protein 152-dependent degradation of TSPAN12 suppresses hepatocellular carcinoma progression

BACKGROUND

Hepatocellular carcinoma (HCC) is the third cause of cancer death in the world, and few molecularly targeted anticancer therapies have been developed to treat it. The E3 ubiquitin ligase RNF152 has been reported to regulate the activity of the mechanistic target of rapamycin complex 1 (mTORC1), induce autophagy and apoptosis. However, the relationship between RNF152 and HCC is unclear.

METHODS

Transcriptome RNA-sequencing data of HCC samples and normal tissues were used to detect the mRNA expression of RNF152. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were used to determine the transcriptional regulation of RNF152 in HCC by FoxO1. RNAi, cell proliferation, colony formation and transwell assays were used to determine the in vitro functions of RNF152. Mouse xenograft models were used to study the in vivo effects of RNF152. The immunoprecipitation assay was used to determine the interaction between RNF152 and TSPAN12. The in vivo ubiquitination assay was performed to determine the regulation of TSPAN12 by RNF152.

RESULTS

We found that RNF152 is significantly down-regulated in clinic HCC samples, and its down-regulation is associated with pool overall survival (OS), progression-free survival (PFS) and disease-specific survival (DSS) in HCC patients. The transcription factor FoxO1 was significantly positively correlated RNF152 expression in HCC tissues. FoxO1 recognizes a classic insulin response element (IRE) on the RNF152 promoter to regulate its expression in HCC. RNF152 suppressed HCC cell proliferation, clonogenic survival, invasion in vitro, and tumorigenesis in vivo. Mechanistically, RNF152 interacted with TSPAN12 and targeted it for ubiquitination and proteasomal degradation, thereby inhibiting TSPAN12-dependent CXCL6 expression and HCC progression.

CONCLUSION

Collectively, our data revealed a tumor suppressor role of RNF152 and a connection between RNF152 and FoxO1 in HCC. Our results support an important role of the FoxO1-RNF152-TSPAN12 axis in the development of HCC. Therapeutic targeting this axis may be an effective means of treating HCC.

miR-196b-5p-mediated downregulation of TSPAN12 and GATA6 promotes tumor progression in non-small cell lung cancer

Lung cancer is the leading cause of cancer-related deaths worldwide and non-small cell lung cancer (NSCLC) accounts for over 80% of lung cancer cases. The RNA binding protein, QKI, belongs to the STAR family and plays tumor-suppressive functions in NSCLC. QKI-5 is a major isoform of QKIs and is predominantly expressed in NSCLC. However, the underlying mechanisms of QKI-5 in NSCLC progression remain unclear. We found that QKI-5 regulated microRNA (miRNA), miR-196b-5p, and its expression was significantly up-regulated in NSCLC tissues. Up-regulated miR-196b-5p promotes lung cancer cell migration, proliferation, and cell cycle through directly targeting the tumor suppressors, GATA6 and TSPAN12. Both GATA6 and TSPAN12 expressions were down-regulated in NSCLC patient tissue samples and were negatively correlated with miR-196b-5p expression. Mouse xenograft models demonstrated that miR-196b-5p functions as a potent onco-miRNA, whereas TSPAN12 functions as a tumor suppressor in NSCLC in vivo. QKI-5 bound to miR-196b-5p and influenced its stability, resulting in up-regulated miR-196b-5p expression in NSCLC. Further analysis showed that hypomethylation in the promoter region enhanced miR-196b-5p expression in NSCLC. Our findings indicate that QKI-5 may exhibit novel anticancer mechanisms by regulating miRNA in NSCLC, and targeting the QKI5∼miR-196b-5p∼GATA6/TSPAN12 pathway may enable effectively treating some NSCLCs.

TSPAN12 Precedes Tumor Proliferation by Cell Cycle Control in Ovarian Cancer

TSPAN12, a member of the tetraspanin family, has been highly connected with the pathogenesis of cancer. Its biological function, however, especially in ovarian cancer (OC), has not been well elucidated. In this study, The Cancer Genome Atlas (TCGA) dataset analysis revealed that upregulation of TSPAN12 gene expression was significantly correlated with patient survival, suggesting that TSPAN12 might be a potential prognostic marker for OC. Further exploration showed that TSPAN12 overexpression accelerated proliferation and colony formation of OVCAR3 and SKOV3 OC cells. Knockdown of TSPAN12 expression in A2780 and SKOV3 cells decreased both proliferation and colony formation. Western blot analysis showed that several cyclins and cyclin-dependent kinases (CDK) (e.g., Cyclin A2, Cyclin D1, Cyclin E2, CDK2, and CDK4) were significantly involved in the regulation of cell cycle downstream of TSPAN12. Moreover, TSPAN12 accelerated mitotic progression by controlling cell cycle. Thus, our data demonstrated that TSPAN12 could be a novel molecular target for the treatment of OC.

Correlative analysis of miR-34b and p53 with pathological characteristics of NSCLC

The expression of miR-34b and p53 in non-small cell lung cancer (NSCLC) was investigated to explore its relationship with clinical pathology of NSCLC. Reverse transcription-quantitative PCR (RT-qPCR) method was used to quantitatively analyze miR-34b and p53 in cancer tissue and adjacent paraneoplastic (PTLC) tissue in 54 cases of NSCLC. The relationship between gene expression and clinical pathological data was analyzed. The expression of miR-34b in tumor tissues of NSCLC patients was significantly downregulated in comparison with PTLC. The expression level of miR-34b was negatively correlated with lymph node metastasis. It was positively correlated with the degree of differentiation and negatively correlated with the pathological stage (P<0.05). There was no significant association in the expression of miR-34b with age, sex, histological type, and gross classification (all P>0.05). The expression of p53 in the tumor tissue of NSCLC patients was significantly reduced in comparison with PTLC, and its expression was negatively correlated with the pathological stage, lymph node metastasis, and was positively correlated with the degree of differentiation. The expression of p53 in adenocarcinoma was generally higher than that of squamous cell carcinoma and large cell carcinoma. The expression of p53 in central type cancer was significantly higher than that in peripheral type (P<0.05). The expression of miR-34b and p53 was positively correlated in NSCLC tissues (r=0.797, P<0.001). The high expression of miR-34b and p53 is closely related to the clinical stage and pathological grade of NSCLC. miR-34b and p53 may serve as important tumor markers for NSCLC.