TSG101 Silencing Suppresses Hepatocellular Carcinoma Cell Growth by Inducing Cell Cycle Arrest and Autophagic Cell Death

VPS25 Promotes an Immunosuppressive Microenvironment in Head and Neck Squamous Cell Carcinoma

The ESCRT (endosomal sorting complex required for transport) machinery is essential for various cellular processes, yet its role in head and neck squamous cell carcinoma (HNSCC) is poorly understood. We utilized The Cancer Genome Atlas (TCGA) datasets to analyze the expression of ESCRT genes. Bulk RNA-sequencing data and HNSCC tissue microarrays (TMAs) were used to evaluate VPS25 expression and its clinical significance. Single-cell RNA sequencing of tumor tissues and VPS25 knockdown experiments in CAL27 cells were used to investigate its biological functions. Immunohistochemistry, spatial transcriptomics, and immunotherapy datasets highlighted the involvement of VPS25 in immune suppression and its potential as a predictive biomarker. The results demonstrated significant VPS25 overexpression in HNSCC tissues, which correlated with poor clinical outcomes. It promoted tumor cell proliferation and migration while reducing immune cell infiltration in the tumor microenvironment (TME). Additionally, by upregulating PVR expression in tumor cells, VPS25 activated the immunosuppressive PVR-TIGIT signaling axis, thereby facilitating immune evasion. Furthermore, VPS25 emerged as a potential biomarker for predicting immunotherapy response. These findings highlight VPS25 as a pivotal regulator of tumor progression and immune evasion in HNSCC and a promising target for therapeutic strategies.

TSG101 overexpression enhances metastasis in oral squamous cell carcinoma through cell cycle regulation

The tumor susceptibility gene 101 (TSG101) was firstly identified as a tumor-inhibiting factor in 1996. Subsequent studies gradually revealed its crucial role in several important cellular processes, including cell survival, vesicle transportation, viral infection, etc. Additionally, TSG101 has been identified as an oncoprotein in certain tumorigenic processes. These conflicting findings suggest that TSG101 might exhibit tumor heterogeneity. Currently, the expression pattern and function of TSG101 in oral squamous cell carcinoma (OSCC) are still untouched. Herein, we reported that TSG101 expression is upregulated and is associated with poorer survival and a higher propensity for lymph node metastasis in OSCC patients. In vivo mouse models confirmed that TSG101 down-regulation effectively inhibited the pulmonary metastases of human OSCC cells. In vitro cell experiments not only proved that TSG101 knockdown significantly disrupted metastasis-related phenotypes in different OSCC cell lines, but also revealed that TSG101 possibly controls the cell cycle through regulating the transcription of Cyclin A/B to play these roles. Additionally, we further validated these findings with a mouse cell line and murine orthotopic OSCC models. Collectively, the oncoprotein function of TSG101 in OSCC is evident from this study. We offer fresh insights into the heterogeneity of TSG101 and highlight new potential targets for OSCC management.

TSG101 Promotes the Proliferation, Migration, and Invasion of Human Glioma Cells by Regulating the AKT/GSK3β/β-Catenin and RhoC/Cofilin Pathways

The tumor susceptibility gene 101 (TSG101) has been reported to play important roles in the development and progression of several human cancers, such as pancreatic cancer, prostate cancer, and hepatocellular carcinoma. However, its potential roles and underlined mechanisms in human glioma are still needed to be further clarified. This study was designed to assess the expression of TSG101 in glioma patients and its effects on glioma cell proliferation, migration, and invasion. Publicly available data revealed that TSG101 mRNA was significantly upregulated in glioma tissues, and high levels of TSG101 were associated with poor prognosis in glioma patients. Western blot and immunohistochemistry experiments further showed that the expression level of TSG101 protein was significantly upregulated in glioma patients, especially in the patients with high-grade glioma. The functional studies showed that knockdown of TSG101 suppressed the proliferation, migration, and invasion of glioma cells, while overexpression of TSG101 facilitated them. Mechanistic studies indicated that the proliferation, migration, and invasion induced by TSG101 in human glioma were related to AKT/GSK3β/β-catenin and RhoC/Cofilin signaling pathways. In conclusion, the above results suggest that the expression of TSG101 is elevated in glioma patients, which accelerates the proliferation, migration, and invasion of glioma cells by regulating the AKT/GSK3β/β-catenin and RhoC/Cofilin pathways.

The Multifaceted Roles of the Tumor Susceptibility Gene 101 (TSG101) in Normal Development and Disease

The multidomain protein encoded by the Tumor Susceptibility Gene 101 (TSG101) is ubiquitously expressed and is suggested to function in diverse intracellular processes. In this review, we provide a succinct overview of the main structural features of the protein and their suggested roles in molecular and cellular functions. We then summarize, in more detail, key findings from studies using genetically engineered animal models that demonstrate essential functions of TSG101 in cell proliferation and survival, normal tissue homeostasis, and tumorigenesis. Despite studies on cell lines that provide insight into the molecular underpinnings by which TSG101 might function as a negative growth regulator, a biologically significant role of TSG101 as a tumor suppressor has yet to be confirmed using genuine in vivo cancer models. More recent observations from several cancer research teams suggest that TSG101 might function as an oncoprotein. A potential role of post-translational mechanisms that control the expression of the TSG101 protein in cancer is being discussed. In the final section of the review, we summarize critical issues that need to be addressed to gain a better understanding of biologically significant roles of TSG101 in cancer.

Mechanical Stress-Dependent Autophagy Component Release via Extracellular Nanovesicles in Tumor Cells

Tumor cells metastasizing through the bloodstream or lymphatic systems must withstand acute shear stress (ASS). Autophagy is a cell survival mechanism that functions in response to stressful conditions, but also contributes to cell death or apoptosis. We predicted that a compensation pathway to autophagy exists in tumor cells subjected to mechanical stress. We found that ASS promoted autophagosome (AP) accumulation and induced release of extracellular nanovesicles (EVs) containing autophagy components. Furthermore, we found that ASS promoted autophagic vesicles fused with multivesicular body (MVB) to form an AP-MVB compartment and then induced autophagy component release into the extracellular space via EVs through the autophagy-MVB-exosome pathway. More importantly, either increasing intracellular autophagosome accumulation or inhibiting autophagic degradation promoted AP-MVB accumulation but did not induce autophagy-associated protein release via EVs except under ASS, demonstrating the existence of a mechanical stress-dependent compensation pathway. Together, these findings revealed that EVs provide an additional protection mechanism for tumor cells and counteract autophagy to maintain cellular homeostasis under acute shear stress.

siRNA against TSG101 reduces proliferation and induces G0/G1 arrest in renal cell carcinoma - involvement of c-myc, cyclin E1, and CDK2

Objective

The tumor susceptibility gene 101 (TSG101) is closely associated with various tumor types, but its role in the pathogenesis of renal cell carcinoma (RCC) is still unknown. This study used RNA interference to silence the expression of TSG101 in RCC cell lines and explore the role of TSG101 in RCC.

Methods

Immunohistochemistry and western blot were performed to detect the expression of TSG101 in 15 paired renal tumor samples. A small interfering RNA (siRNA) targeting TSG101 was transfected into A498 and 786-O cell lines. The Cell Counting Kit-8 (CCK-8) assay and colony formation assay were used to observe the changes in cell proliferation after transfection. Flow cytometry was used to detect the effect on the cell cycle. Western blot was conducted to study the changes of related functional proteins.

Results

The expression of TSG101 was higher in RCC tissues than in adjacent normal tissues. The CCK-8 assay showed that the proliferation and colony formation of the A498 and 786-O cell lines were attenuated after suppression of TSG101. Flow cytometry showed that silencing of TSG101 induced G0/G1 arrest. The western blot results revealed that the levels of cell cycle-related proteins (c-myc, cyclin E1 and cyclin-dependent kinase 2 (CDK2)) were markedly decreased in the siRNA groups.

Conclusions

TSG101 promotes proliferation of RCC cells. This positive effect on tumor growth involves activation of c-myc and cyclin E1/CDK2 and their effect on cell cycle distribution.

Tumor Susceptibility Gene 101 Mediates Anoikis Resistance of Metastatic Thyroid Cancer Cells

BACKGROUND/AIM

Resistance to anoikis is a pre-requisite step in metastasis, a major cause of death in patients with cancer, including thyroid cancer. Impairing anoikis resistance is a possible strategy for therapy of metastatic cancer. We, therefore, we aimed to investigate the key players of anoikis resistance.

MATERIALS AND METHODS

Papillary-type (BCPAP), follicular-type (FTC133), and anaplastic-type (ARO) thyroid carcinoma cells, cultured in poly(2-hydroxyethyl methacrylate)-coated plates to mimic circulating cells, were used as model systems in this study. Flow cytometry and soft-agar assays were used to determine cells exhibiting anoikis resistance. Proteomics was used to identify candidate proteins and validated using western blot and siRNA knockdown.

RESULTS

Only ARO cells showed both anoikis resistance potential and anchorage-independent growth ability. Tumor susceptibility gene 101 protein (TSG101) was identified to be potentially important in anoikis resistance, which was confirmed by an increase in anoikis and expression of a pro-apoptotic protein (BCL-2 like protein 4) and an apoptotic marker (cleaved poly-ADP ribose polymerase) in floating siTSG101-knockdown cells.

CONCLUSION

To our knowledge, this is the first study that implicates the importance of TSG101 in anoikis resistance of thyroid cancer.

TSG101 promotes the proliferation, migration and invasion of hepatocellular carcinoma cells by regulating the PEG10

The tumour susceptibility gene 101 (TSG101) is reported to play important roles in the development and progression of several human cancers. However, its potential roles and underlined mechanisms in human hepatocellular carcinoma (HCC) are still needed to be further clarified. In the present study, we reported that knock down of TSG101 suppressed the proliferation, migration and invasion of HCC cells, while overexpression of TSG101 facilitated them. Molecularly, the results revealed that knock down of TSG101 significantly decreased the cell cycle related regulatory factor p53 and p21. In another point, knock down of TSG101 also obviously decreased the level of metallopeptidase inhibitor TIMP1 (Tissue inhibitors of metalloproteinases 1), which results in inhibition of MMP2, MMP7 and MMP9. In contrast, overexpression of TSG101 had opposite effects. The iTRAQ proteomics analysis identified that oncogenic protein PEG10 (Paternally expressed gene 10) might be a potential downstream target of TSG101. Further investigation showed that TSG101 interacted with PEG10 and protected it from proteasomal degradation thereby regulating the expression of p53, p21 and MMPs. Finally, we found that both TSG101 and PEG10 proteins are up-regulated and presented a direct correlation in HCC patients. In conclusion, these results suggest that TSG101 is up-regulated in human HCC patients, which may accelerate the proliferation, migration and invasion of HCC cells through regulating PEG10.

MicroRNA-766-3p Inhibits Tumour Progression by Targeting Wnt3a in Hepatocellular Carcinoma

Recent studies have indicated that microRNAs (miRNAs) play an important role in hepatocellular carcinoma (HCC) progression. In this study, we showed that miR-766-3p was decreased in approximately 72% of HCC tissues and cell lines, and its low expression level was significantly correlated with tumour size, TNM stage, metastasis, and poor prognosis in HCC. Ectopic miR-766-3p expression inhibited HCC cell proliferation, colony formation, migration and invasion. In addition, we showed that miR-766-3p repressed Wnt3a expression. A luciferase reporter assay revealed that Wnt3a was a direct target of miR-766-3p, and an inverse correlation between miR-766-3p and Wnt3a expression was observed. Moreover, Wnt3a up-regulation reversed the effects of miR-766-3p on HCC progression. In addition, our study showed that miR-766-3p up-regulation decreased the nuclear β-catenin level and expression of Wnt targets (TCF1 and Survivin) and reduced the level of MAP protein regulator of cytokinesis 1 (PRC1). However, these effects of miR-766-3p were reversed by Wnt3a up-regulation. In addition, PRC1 up-regulation increased the nuclear β-catenin level and protein expression of TCF1 and Survivin. iCRT3, which disrupts the β-catenin-TCF4 interaction, repressed the TCF1, Survivin and PRC1 protein levels. Taken together, our results suggest that miR-766-3p down-regulation promotes HCC cell progression, probably by targeting the Wnt3a/PRC1 pathway, and miR-766-3p may serve as a potential therapeutic target in HCC.

DNM3 Attenuates Hepatocellular Carcinoma Growth by Activating P53

BACKGROUND

Primary hepatocellular carcinoma is one of the most common malignant tumors in China and its mortality rate shows no sign at present of ceasing to rise. In our previous study, we found that the mRNA level of Dynamin3 (DNM3), a member of the Dynamin family, is significantly lower in hepatocellular carcinoma tissues than in non-tumor tissues. The aim of this study was to investigate the expression pattern and potential function of DNM3 in hepatocellular carcinoma.

MATERIAL/METHODS

First, we determined the expression ofDNM3 in human hepatocellular carcinoma tissues and cell lines. We then studied the biological function of DNM3 on hepatocellular carcinoma cells by proliferation assay and colony formation assay. Flow cytometry was used to study the effect of DNM3 on cell cycle and apoptosis.

RESULTS

Expression of DNM3 was significantly downregulated in hepatocellular carcinoma tissues and was associated with vein invasion and tumor metastasis. In addition, upregulation of DNM3 reduced hepatocellular carcinoma cell proliferation and colony formation, induced hepatocellular carcinoma cell G0/G1 phase arrest, and stimulated hepatocellular carcinoma cell apoptosis. We also found that DNM3 may exert its anti-proliferative effect through upregulating p53.

CONCLUSIONS

Our findings suggest that DNM3 attenuates the proliferation and induces apoptosis of gastric cancer cells. Modulation of DNM3 may prove to be an efficient method of hepatocellular carcinoma treatment.