Tetraspanin-8 promotes hepatocellular carcinoma metastasis by increasing ADAM12m expression

Molecular Regulation and Oncogenic Functions of TSPAN8

Tetraspanins, a superfamily of small integral membrane proteins, are characterized by four transmembrane domains and conserved protein motifs that are configured into a unique molecular topology and structure in the plasma membrane. They act as key organizers of the plasma membrane, orchestrating the formation of specialized microdomains called "tetraspanin-enriched microdomains (TEMs)" or "tetraspanin nanodomains" that are essential for mediating diverse biological processes. TSPAN8 is one of the earliest identified tetraspanin members. It is known to interact with a wide range of molecular partners in different cellular contexts and regulate diverse molecular and cellular events at the plasma membrane, including cell adhesion, migration, invasion, signal transduction, and exosome biogenesis. The functions of cell-surface TSPAN8 are governed by ER targeting, modifications at the Golgi apparatus and dynamic trafficking. Intriguingly, limited evidence shows that TSPAN8 can translocate to the nucleus to act as a transcriptional regulator. The transcription of TSPAN8 is tightly regulated and restricted to defined cell lineages, where it can serve as a molecular marker of stem/progenitor cells in certain normal tissues as well as tumors. Importantly, the oncogenic roles of TSPAN8 in tumor development and cancer metastasis have gained prominence in recent decades. Here, we comprehensively review the current knowledge on the molecular characteristics and regulatory mechanisms defining TSPAN8 functions, and discuss the potential and significance of TSPAN8 as a biomarker and therapeutic target across various epithelial cancers.

ADAM12 promotes the resistance of lung adenocarcinoma cells to EGFR-TKI and regulates the immune microenvironment by activating PI3K/Akt/mTOR and RAS signaling pathways

Lung adenocarcinoma (LUAD) is a malignant respiratory disease, resulting in a heavy social burden. Epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance and tumor immune microenvironment are important directions in the treatment of LUAD. In this study, we confirmed the role of ADAM metallopeptidase domain 12 (ADAM12) in LUAD development and progression. Our bioinformatic analysis was conducted to screen ADAM12 was correlated with EGFR-TKI and immune infiltration in LUAD patients. Our results showed that the transcription and post-transcription level of ADAM12 is significantly increased in tumor samples compared to normal samples, and ADAM12 correlated with poor prognosis in LUAD patients. High level of ADAM12 accelerated the LUAD progression via promoting proliferation, cell cycle, apoptosis escaping, immune escaping, EGFR-TKI resistance, angiogenesis, invasion and migration based on experiment validation in vitro and in vivo, which could be attenuated by ADAM12 knockdown. Further mechanistic studies suggested that the PI3K/Akt/mTOR and RAS signaling pathways were activated after ADAM12 knockdown. Therefore, ADAM12 might be validated as a possible molecular therapy target and prognostic marker for patients with LUAD.

Sequential genome-wide CRISPR-Cas9 screens identify genes regulating cell-surface expression of tetraspanins

Tetraspanins, a superfamily of membrane proteins, mediate diverse biological processes through tetraspanin-enriched microdomains in the plasma membrane. However, how their cell-surface presentation is controlled remains unclear. To identify the regulators of tetraspanin trafficking, we conduct sequential genome-wide loss-of-function CRISPR-Cas9 screens based on cell-surface expression of a tetraspanin member, TSPAN8. Several genes potentially involved in endoplasmic reticulum (ER) targeting, different biological processes in the Golgi apparatus, and protein trafficking are identified and functionally validated. Importantly, we find that biantennary N-glycans generated by MGAT1/2, but not more complex glycan structures, are important for cell-surface tetraspanin expression. Moreover, we unravel that SPPL3, a Golgi intramembrane-cleaving protease reported previously to act as a sheddase of multiple glycan-modifying enzymes, controls cell-surface tetraspanin expression through a mechanism associated with lacto-series glycolipid biosynthesis. Our study provides critical insights into the molecular regulation of cell-surface presentation of tetraspanins with implications for strategies to manipulate their functions, including cancer cell invasion.

Novel antigens for targeted radioimmunotherapy in hepatocellular carcinoma

Liver cancer is the sixth common cancer and forth cause of cancer-related death worldwide. Based on usually advanced stages of hepatocellular carcinoma (HCC) at the time of diagnosis, therapeutic options are limited and, in many cases, not effective, and typically result in the tumor recurrence with a poor prognosis. Radioimmunotherapy (RIT) offers a selective internal radiation therapy approach using beta or alpha emitting radionuclides conjugated with tumor-specific monoclonal antibodies (mAbs), or specific selective peptides. When compared to chemotherapy or radiotherapy, radiolabeled mAbs against cancer-associated antigens could provide a high therapeutic and exclusive radiation dose for cancerous cells while decreasing the exposure-induced side effects to healthy tissues. The recent advances in cancer immunotherapy, such as blockade of immune-checkpoint inhibitors (ICIs), has changed the landscape of cancer therapy, and the efficacy of different classes of immunotherapy has been tested in many clinical trials. Taking into account the use of ICIs in the liver tumor microenvironment, combined therapies with different approaches may enhance the outcome in the future clinical studies. With the development of novel immunotherapy treatment options in the recent years, there has been a great deal of information about combining the diverse treatment modalities to boost the effectiveness of immunomodulatory drugs. In this opinion review, we will discuss the recent advancements in RIT. The current status of immunotherapy and internal radiotherapy will be updated, and we will propose novel approaches for the combination of both techniques. Potential target antigens for radioimmunotherapy in Hepatocellular carcinoma (HCC). HCC radioimmunotherapy target antigens are the most specific and commonly accessible antigens on the surface of HCC cells. CTLA-4 ligand and receptor, TAMs, PD-1/PD-L, TIM-3, specific IEXs/TEXs, ROBO1, and cluster of differentiation antigens CD105, CD147 could all be used in HCC radioimmunotherapy. Abbreviations: TAMs, tumor-associated macrophages; CTLA-4, cytotoxic T-lymphocyte associated antigen-4; PD-1, Programmed cell death protein 1; PD-L, programmed death-ligand1; TIM-3, T-cell immunoglobulin (Ig) and mucin-domain containing protein-3; IEXs, immune cell-derived exosomes; TEXs, tumor-derived exosomes.

Integrated analysis identified NPNT as a potential key regulator in tumor metastasis of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the lethal malignancies worldwide. Tumor metastasis is the main cause of HCC related death. Although progress has been made in the mechanism study of HCC in the past decades, the underlying mechanism of HCC metastasis has not been fully illustrated. In the present study, bioinformatic analysis including weighted gene co-expression network analysis (WGCNA), differentially expressed gene analysis, and gene enrichment analysis were applied to discover genes correlated with HCC metastasis. Immunohistochemistry (IHC) assays were applied to detect the expression of NPNT in HCC samples. Cell transfection, wound healing, matrigel transwell assays, and western blot assays were utilized to evaluate the effects of NPNT on cell migration and invasion and signaling pathway variation. We found that NPNT was up-regulated in HCC tumor tissues compared with normal tissues. Especially, NPNT was highly expressed in metastatic tumor compared with non-metastatic HCC tumors. Down-regulation of NPNT via siRNA transfection inhibited cell migration, invasion, and FAK/PI3K/AKT signaling pathway in HCC. Our results demonstrate that NPNT is a potential key regulator in HCC metastasis.

Role of Tetraspanins in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is characterized by high prevalence, morbidity, and mortality. Liver cancer is the sixth most common cancer worldwide; and its subtype, HCC, accounts for nearly 80% of cases. HCC progresses rapidly, and to date, there is no efficacious treatment for advanced HCC. Tetraspanins belong to a protein family characterized by four transmembrane domains. Thirty-three known tetraspanins are widely expressed on the surface of most nucleated cells and play important roles in different biological processes. In our review, we summarize the functions of tetraspanins and their underlying mechanism in the life cycle of HCC, from its initiation, progression, and finally to treatment. CD9, TSPAN15, and TSPAN31 can promote HCC cell proliferation or suppress apoptosis. CD63, CD151, and TSPAN8 can also facilitate HCC metastasis, while CD82 serves as a suppressor of metastasis. TSPAN1, TSPAN8, and CD151 act as prognosis indicators and are inversely correlated to the overall survival rate of HCC patients. In addition, we discuss the potential of role of the tetraspanin family proteins as novel therapeutic targets and as an approach to overcome drug resistance, and also provide suggestions for further research.

SOX9 is a critical regulator of TSPAN8-mediated metastasis in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is the deadliest cancer mainly owing to its proclivity to early metastasis and the lack of effective targeted therapeutic drugs. Hence, understanding the molecular mechanisms underlying early invasion and metastasis by PDAC is imperative for improving patient outcomes. The present study identified that upregulation of TSPAN8 expression in PDAC facilitates metastasis in vivo and in vitro. We found SOX9 as a key transcriptional regulator of TSPAN8 expression in response to EGF stimulation. SOX9 modulation was sufficient to positively regulate endogenous expression of TSPAN8, with concomitant in vitro phenotypic changes such as loss of cell-matrix adherence and increased invasion. Moreover, increased SOX9 and TSPAN8 levels were shown to correlate in human pancreatic cancer specimens and downregulated in vitro by EGFR tyrosine kinase inhibitors. High expression of SOX9 and TSPAN8 has been associated with tumor stage, poor prognosis and poor patient survival in PDAC. In conclusion, this study highlights the importance of the EGF-SOX9-TSPAN8 signaling cascade in the control of PDAC invasion and implies that TSPAN8 may be a promising novel therapeutic target for the treatment of PDAC.

Actinidia Chinensis Planch Root extract attenuates proliferation and metastasis of hepatocellular carcinoma by inhibiting the DLX2/TARBP2/JNK/AKT pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Many studies have confirmed that traditional Chinese herbs exert potential anti-tumor effects. Actinidia Chinensis Planch root has been used as a traditional Chinese medicine (TCM) for thousands of years. However, the mechanism of anti-tumor effects of Actinidia Chinensis Planch root has not been clearly clarified.

AIM OF THE STUDY

To explore the molecular biological mechanisms underlying the inhibitory effect of Actinidia Chinensis Planch root extract (acRoots) on hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

In our previous study, we used mRNA chip analyses to identify genes regulated by acRoots. Further analyses of altered genes led to the identification of a key regulator of genes that responds to acRoots. We explored the effects of acRoots on the proliferation and invasion of HCC cells via cell counting as well as transwell assays, and further explored the molecular mechanisms underlying the effects of acRoots on HCC cells using qRT-PCR, western blot, and Chip-PCR.

RESULTS

Increasing the concentration of acRoots as well as prolonging its action time enhanced the inhibitory activity of acRoots as well as its cytotoxicity against HCC cells. High TARBP2 expression in HCC cells, which is associated with advanced-stage HCC and poor prognoses in HCC patients, was downregulated by treatment with acRoots. Furthermore, acRoots inhibited proliferation, invasion, and epithelial-to-mesenchymal transition by downregulating TARBP2 expression. HCC cells with higher TARBP2 expression were more sensitive to acRoots. The expression of TARBP2 and DLX2 in HCC patients and HCC cell lines was significantly positively correlated, and DLX2 as a transcription factor may promote TARBP2 expression, thereby further activating the JNK/AKT signaling pathway leading to the inhibition of HCC.

CONCLUSIONS

acRoots inhibited the malignant behavior of HCC cells by inhibiting TARBP2 expression, which is affected by the transcription factor DLX2, leading to a reduction in JNK/AKT signaling pathway activation.

TSPAN8 as a Novel Emerging Therapeutic Target in Cancer for Monoclonal Antibody Therapy

Tetraspanin 8 (TSPAN8) is a member of the tetraspanin superfamily that forms TSPAN8-mediated protein complexes by interacting with themselves and other various cellular signaling molecules. These protein complexes help build tetraspanin-enriched microdomains (TEMs) that efficiently mediate intracellular signal transduction. In physiological conditions, TSPAN8 plays a vital role in the regulation of biological functions, including leukocyte trafficking, angiogenesis and wound repair. Recently, reports have increasingly shown the functional role and clinical relevance of TSPAN8 overexpression in the progression and metastasis of several cancers. In this review, we will highlight the physiological and pathophysiological roles of TSPAN8 in normal and cancer cells. Additionally, we will cover the current status of monoclonal antibodies specifically targeting TSPAN8 and the importance of TSPAN8 as an emerging therapeutic target in cancers for monoclonal antibody therapy.

Extracellular vesicle tetraspanin-8 level predicts distant metastasis in non-small cell lung cancer after concurrent chemoradiation

Non-small cell lung cancer (NSCLC) is the most commonly diagnosed cancer and the leading cause of cancer death worldwide. More than half of patients with NSCLC die after developing distant metastases, so rapid, minimally invasive prognostic biomarkers are needed to reduce mortality. We used proteomics to identify proteins differentially expressed on extracellular vesicles (EVs) of nonmetastatic 393P and metastatic 344SQ NSCLC cell lines and found that tetraspanin-8 (Tspan8) was selectively enriched on 344SQ EVs. NSCLC cell lines treated with EVs overexpressing Tspan8 also exhibited increased Matrigel invasion. Elevated Tspan8 expression on serum EVs of individuals with stage III premetastatic NSCLC tumors was also associated with reduced distant metastasis-free survival, suggesting that Tspan8 levels on serum EVs may predict future metastasis. This result suggests that a minimally invasive blood test to analyze EV expression of Tspan8 may be of potential value to guide therapeutic decisions for patients with NSCLC and merits further study.

A Positive Tetraspanin 8 (TSPAN8)/β-Catenin Regulatory Loop Enhances the Stemness of Colorectal Cancer Cells

BACKGROUND The expression of TSPAN8 (tetraspanin 8) is upregulated in colorectal cancer; however, its roles in colorectal cancer progression are never been revealed. This work aimed to investigate TSPAN8 effects and the molecular basis in regulating colorectal cancer stemness. MATERIAL AND METHODS Real-time quantitative polymerase chain reaction and western blot analysis were used to detect the expression of TSPAN8 expression in clinical samples and the expression of stemness genes in colorectal cancer cells. Sphere forming analysis was performed to detect TSPAN8 effects on sphere forming ability of colorectal cancer cells. Co-IP and ChIP analysis were performed to confirm the molecular basis contributing to TSPAN8-mediated effects on colorectal cancer stemness. RESULTS TSPAN8 expression is increased in colorectal cancer tissues. Knockdown of TSPAN8 reduced the expression of stemness genes and sphere forming capacity in colorectal cancer cells. Mechanistically, TSPAN8 directly interacted ß-catenin and enhanced its protein expression, which is necessary for TSPAN8-mediated effects on colorectal cancer stemness. Conversely, ß-catenin directly bound to TSPAN8 promoter and enhanced TSPAN8 transcription. CONCLUSIONS TSPAN8 promotes colorectal cancer stemness through a positive TSPAN8/ß-catenin regulatory loop.

CRISPR/Cas9-mediated knockout of NSD1 suppresses the hepatocellular carcinoma development via the NSD1/H3/Wnt10b signaling pathway

Background

The NSD family of histone lysine methyltransferases have emerged as important biomarkers that participate in a variety of malignancies. Recent evidence has indicated that somatic dysregulation of the nuclear receptor binding SET domain-containing protein 1 (NSD1) is associated with the tumorigenesis in HCC, suggesting that NSD1 may serve as a prognostic target for this malignant tumor. However, its mechanism in human hepatocellular carcinoma (HCC), the major primary malignant tumor in the human liver, remains unclear. Hence, we investigated how NSD1 regulated HCC progression via regulation of the Wnt/β-catenin signaling pathway.

Methods

Reverse transcription quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis was performed to identify the expression of NSD1 in HCC cells and clinically obtained tissues. The relationship between NSD1 expression and prognosis was analyzed by Kaplan-Meier survival curve. Further, a NSD1 knockout cell line was constructed by CRISPR/Cas9 genomic editing system, which was investigated in a battery of assays such as HCC cell proliferation, migration and invasion, followed by the investigation into NSD1 regulation on histone H3, Wnt10b and Wnt/β-catenin signaling pathway via ChIP. Finally, a nude mouse xenograft model was conducted in order to assess tumorigenesis affected by NSD1 knockout in vivo.

Results

NSD1 was overexpressed in HCC tissues and cell lines in association with poor prognosis. Knockout of NSD1 inhibited the proliferation, migration and invasion abilities of HCC cells. CRISPR/Cas9-mediated knockout of NSD1 promoted methylation of H3K27me3 and reduced methylation of H3K36me2, which inhibited Wnt10b expression. The results thereby indicated an inactivation of the Wnt/β-catenin signaling pathway suppressed cell proliferation, migration and invasion in HCC. Moreover, these in vitro findings were reproduced in vivo on tumor xenograft in nude mice.

Conclusion

In conclusion, the study provides evidence that CRISPR/Cas9-mediated NSD1 knockout suppresses HCC cell proliferation and migration via the NSD1/H3/Wnt10b signaling pathway, suggesting that NSD1, H3 and Wnt10b may serve as potential targets for HCC.

The Pancreatic Cancer-Initiating Cell Marker CD44v6 Affects Transcription, Translation, and Signaling: Consequences for Exosome Composition and Delivery

Pancreatic cancer-initiating cells (PaCIC) express CD44v6 and Tspan8. A knockdown (kd) of these markers hinders the metastatic capacity, which can be rescued, if the cells are exposed to CIC-exosomes (TEX). Additional evidence that CD44v6 regulates Tspan8 expression prompted us to explore the impact of these PaCIC markers on nonmetastatic PaCa and PaCIC-TEX. We performed proteome, miRNA, and mRNA deep sequencing analyses on wild-type, CD44v6kd, and Tspan8kd human PaCIC and TEX. Database comparative analyses were controlled by qRT-PCR, Western blot, flow cytometry, and confocal microscopy. Transcriptome analysis of CD44 versus CD44v6 coimmunoprecipitating proteins in cells and TEX revealed that Tspan8, several signal-transducing molecules including RTK, EMT-related transcription factors, and proteins engaged in mRNA processing selectively associate with CD44v6 and that the membrane-attached CD44 intracytoplasmic tail supports Tspan8 and NOTCH transcription. Deep sequencing uncovered a CD44v6 contribution to miRNA processing. Due to the association of CD44v6 with Tspan8 in internalization prone tetraspanin-enriched membrane domains (TEM) and the engagement of Tspan8 in exosome biogenesis, most CD44v6-dependent changes were transferred into TEX such that the input of CD44v6 to TEX activities becomes largely waved in both a CD44v6kd and a Tspan8kd. Few differences between CD44v6kd- and Tspan8kd-TEX rely on CD44v6 being also recovered in non-TEM derived TEX, highlighting distinct TEX delivery from individual cells that jointly account for TEX-promoted target modulation. This leads us to propose a model in which CD44v6 strongly supports tumor progression by cooperating with signaling molecules, altering transcription of key molecules, and through its association with the mRNA processing machinery. The association of CD44v6 with Tspan8, which plays a crucial role in vesicle biogenesis, promotes metastases by transferring CD44v6 activities into TEM and TEM-independently derived TEX. Further investigations of the lead position of CD44v6 in shifting metastasis-promoting activities into CIC-TEX may offer a means of targeting TEX-CD44v6 in therapeutic applications.

Exosomes, metastases, and the miracle of cancer stem cell markers

Cancer-initiating cells (CIC) are the driving force in tumor progression. There is strong evidence that CIC fulfill this task via exosomes (TEX), which modulate and reprogram stroma, nontransformed cells, and non-CIC. Characterization of CIC, besides others, builds on expression of CIC markers, many of which are known as metastasis-associated molecules. We here discuss that the linkage between CIC/CIC-TEX and metastasis-associated molecules is not fortuitously, but relies on the contribution of these markers to TEX biogenesis including loading and TEX target interactions. In addition, CIC markers contribute to TEX binding- and uptake-promoted activation of signaling cascades, transcription initiation, and translational control. Our point of view will be outlined for pancreas and colon CIC highly expressing CD44v6, Tspan8, EPCAM, claudin7, and LGR5, which distinctly but coordinately contribute to tumor progression. Despite overwhelming progress in unraveling the metastatic cascade and the multiple tasks taken over by CIC-TEX, there remains a considerable gap in linking CIC biomarkers, TEX, and TEX-initiated target modulation with metastasis. We will try to outline possible bridges, which could allow depicting pathways for new and expectedly powerful therapeutic interference with tumor progression.

Pancreatic cancer-initiating cell exosome message transfer into noncancer-initiating cells: the importance of CD44v6 in reprogramming

BACKGROUND

Cancer-initiating cell (CIC) exosomes (CIC-TEX) are suggested reprogramming Non-CIC. Mode of message transfer and engagement of CIC-markers being disputed, we elaborated the impact of CD44v6 and Tspan8 on the response of Non-CIC.

METHODS

Non-metastasizing CD44v6- and Tspan8-knockdown (kd) pancreatic cancer cells served as Non-CIC. CIC-TEX coculture-induced changes were evaluated by deep-sequencing and functional assays. Tumor progression was surveyed during in vivo CIC-TEX treatment.

RESULTS

Deep-sequencing of CIC-TEX-cocultured CD44v6kd-Non-CIC revealed pronounced mRNA changes in signaling, transport, transcription and translation; altered miRNA affected metabolism, signaling and transcription. CIC-TEX coculture-induced changes in Tspan8kd-Non-CIC mostly relied on CIC-TEX-Tspan8 being required for targeting. CIC-TEX transfer supported apoptosis resistance and significantly promoted epithelial mesenchymal transition, migration, invasion and (lymph)angiogenesis of the kd Non-CIC in vitro and in vivo, deep-sequencing allowing individual mRNA and miRNA assignment to altered functions. Importantly, CIC-TEX act as a hub, initiated by CD44v6-dependent RTK, GPCR and integrin activation and involving CD44v6-assisted transcription and RNA processing. Accordingly, a kinase inhibitor hampered CIC-TEX-fostered tumor progression, which was backed by an anti-Tspan8 blockade of CIC-TEX binding.

CONCLUSIONS

This in depth report on the in vitro and in vivo impact of CIC-TEX on CD44v6kd and Tspan8kd Non-CIC unravels hub CIC-TEX activity, highlighting a prominent contribution of the CIC-markers CD44v6 to signaling cascade activation, transcription, translation and miRNA processing in Non-CIC and of Tspan8 to CIC-TEX targeting. Blocking CIC-TEX binding/uptake and uptake-initiated target cell activation significantly mitigated the deleterious CIC-TEX impact on CD44v6kd and Tspan8kd Non-CIC.

Actinidia chinensis Planch root extract attenuates proliferation and metastasis of hepatocellular carcinoma by inhibiting epithelial-mesenchymal transition

ETHNO-PHARMACOLOGICAL RELEVANCE

Numerous studies have demonstrated the potent anticancer activity of various Chinese herbs. Actinidia chinensis Planch root (acRoots), a traditional Chinese medicine, functions as an antitumor and detoxifying agent and plays a role in diuresis and hemostasis. Treatment with acRoots confers strong inhibition of tumor growth in various forms of cancer. Here, we evaluated the anticancer activity and molecular mechanisms of Actinidia chinensis Planch root extract (acRoots) on hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Our previous study used mRNA chip analyses to identify the genes regulated by acRoots. Further analyses of the altered genes identified a key regulator of genes in response to acRoots. Here, the effects of acRoots on HCC cell proliferation, migration, invasion, and apoptosis were evaluated by cell counting, Transwell and apoptosis assays. In addition, the in vivo anti-HCC effects of acRoots were investigated using an HCC animal model. The expression of a key regulator of genes in response to acRoots was analyzed using quantitative polymerase chain reaction and western blotting.

RESULTS

Treatment with acRoots (10 mg/mL) had no cytotoxicity in L02 cells and had a positive effect on L02 cell viability; however, it significantly inhibited HCC cell proliferation. Treatment with acRoots downregulated DLX2 gene expression in HCC cells, and high DLX2 expression was associated with advanced stage and poor prognosis in patients with HCC. Treatment with acRoots inhibited proliferation, invasion and migration, clonality, and the epithelial-to-mesenchymal transition, and promoted the apoptosis of HCC cells by downregulating DLX2 expression. HCC cells with higher DLX2 expression were more sensitive to acRoots.

CONCLUSIONS

acRoots inhibited the malignant biological behavior of HCC cells via regulation of the epithelial-mesenchymal transition (EMT) by DLX2.

Blood-based analysis of type-2 diabetes mellitus susceptibility genes identifies specific transcript variants with deregulated expression and association with disease risk

Despite significant progress by genome-wide association studies, the ability of genetic variants to conduce to the prediction or prognosis of type-2 diabetes (T2D) is weak. Expression analysis of the corresponding genes may suggest possible links between single-nucleotide polymorphisms and T2D phenotype and/or risk. Herein, we investigated the expression patterns of 24 T2D-susceptibility genes, and their individual transcript variants (tv), in peripheral blood of T2D patients and controls (CTs), applying RNA-seq and real-time qPCR methodologies, and explore possible associations with disease features. Our data revealed the deregulation of certain transcripts in T2D patients. Among them, the down-regulation of CAPN10 tv3 was confirmed as an independent predictor for T2D. In patients, increased expression of CDK5 tv2, CDKN2A tv3 or THADA tv5 correlated positively with serum insulin levels, of CDK5 tv1 positively with % HbA1c levels, while in controls, elevated levels of TSPAN8 were associated positively with the presence of T2D family history. Herein, a T2D-specific expression profile of specific transcripts of disease-susceptibility genes is for the first time described in human peripheral blood. Large-scale studies are needed to evaluate the potential of these molecules to serve as disease biomarkers.

Ping-Pong-Tumor and Host in Pancreatic Cancer Progression

Metastasis is the main cause of high pancreatic cancer (PaCa) mortality and trials dampening PaCa mortality rates are not satisfying. Tumor progression is driven by the crosstalk between tumor cells, predominantly cancer-initiating cells (CIC), and surrounding cells and tissues as well as distant organs, where tumor-derived extracellular vesicles (TEX) are of major importance. A strong stroma reaction, recruitment of immunosuppressive leukocytes, perineural invasion, and early spread toward the peritoneal cavity, liver, and lung are shared with several epithelial cell-derived cancer, but are most prominent in PaCa. Here, we report on the state of knowledge on the PaCIC markers Tspan8, alpha6beta4, CD44v6, CXCR4, LRP5/6, LRG5, claudin7, EpCAM, and CD133, which all, but at different steps, are engaged in the metastatic cascade, frequently via PaCIC-TEX. This includes the contribution of PaCIC markers to TEX biogenesis, targeting, and uptake. We then discuss PaCa-selective features, where feedback loops between stromal elements and tumor cells, including distorted transcription, signal transduction, and metabolic shifts, establish vicious circles. For the latter particularly pancreatic stellate cells (PSC) are responsible, furnishing PaCa to cope with poor angiogenesis-promoted hypoxia by metabolic shifts and direct nutrient transfer via vesicles. Furthermore, nerves including Schwann cells deliver a large range of tumor cell attracting factors and Schwann cells additionally support PaCa cell survival by signaling receptor binding. PSC, tumor-associated macrophages, and components of the dysplastic stroma contribute to perineural invasion with signaling pathway activation including the cholinergic system. Last, PaCa aggressiveness is strongly assisted by the immune system. Although rich in immune cells, only immunosuppressive cells and factors are recovered in proximity to tumor cells and hamper effector immune cells entering the tumor stroma. Besides a paucity of immunostimulatory factors and receptors, immunosuppressive cytokines, myeloid-derived suppressor cells, regulatory T-cells, and M2 macrophages as well as PSC actively inhibit effector cell activation. This accounts for NK cells of the non-adaptive and cytotoxic T-cells of the adaptive immune system. We anticipate further deciphering the molecular background of these recently unraveled intermingled phenomena may turn most lethal PaCa into a curatively treatable disease.

Tspan8 and Tspan8/CD151 knockout mice unravel the contribution of tumor and host exosomes to tumor progression

BACKGROUND

The tetraspanins Tspan8 and CD151 promote metastasis, exosomes (Exo) being suggested to be important in the crosstalk between tumor and host. The contribution of Tspan8 and CD151 to host versus tumor-derived exosome (TEX) activities being not defined, we approached the questions using 3-methylcholanthrene-induced (MCA) tumors from wt, Tspan8ko, CD151ko and Tspan8/CD151 (db)ko mice, implanted into tetraspanin-competent and deficient hosts.

METHODS

Tumor growth and dissemination, hematopoiesis and angiogenesis were surveyed in wild type (wt), Tspan8ko, CD151ko and dbko mice bearing tetraspanin-competent and -deficient MCA tumors. In vitro studies using tumor cells, bone marrow cells (BMC) and endothelial cells (EC) elaborated the mechanism of serum (s)Exo- and TEX-induced target modulation.

RESULTS

Tumors grew in autochthonous and syngeneic hosts differing in Tspan8- and/or CD151-competence. However, Tspan8ko- and/or CD151ko-tumor cell dissemination and settlement in metastatic organs was significantly reduced in the autochthonous host, and less severely in the wt-host. Impaired wt-MCA tumor dissemination in the ko-host confirmed a contribution of host- and tumor-Tspan8/-CD151 to tumor cell dissemination, delivery of sExo and TEX being severely impaired by a Tspan8ko/CD151ko. Coculturing tumor cells, BMC and EC with sExo and TEX revealed minor defects in epithelial mesenchymal transition and apoptosis resistance of ko tumors. Strongly reduced migratory and invasive capacity of Tspan8ko/CD151ko-MCA relies on distorted associations with integrins and CAM and missing Tspan8/CD151-promoted recruitment of proteases. The defects, differing between Tspan8ko- and CD151ko-MCA, were rescued by wt-TEX and, less efficiently Tspan8ko- and CD151ko-TEX. Minor defects in hematopoietic progenitor maturation were based on the missing association of hematopoietic growth factors /- receptors with CD151 and, less pronounced, Tspan8. Rescue of impaired angiogenesis in ko mice by wt-sExo and promotion of angiogenesis by TEX depended on the association of Tspan8 and CD151 with GPCR and RTK in EC and tumor cells.

CONCLUSIONS

Tspan8-/CD151-TEX play central roles in tumor progression. Tspan8-/CD151-sExo and TEX contribute by stimulating angiogenesis. Tspan8 and CD151 fulfill these tasks by associating with function-relevant proteins, the additive impact of Tspan8 and CD151 relying on differences in preferred associations. The distinct Tspan8 and CD151 contributions suggest a blockade of TEX-Tspan8 and -CD151 promising for therapeutic intervention.

Immune Targeting of Tetraspanins Involved in Cell Invasion and Metastasis

Metastasis is the ultimate consequence of cancer progression and the cause of patients’ death across different cancer types. Patients with initial diagnosis of distant disease have a worst 5-year survival compared to patients with localized disease. Therapies that target primary tumors fail to eradicate distant dissemination of cancer. Recently, immunotherapies have improved the survival of patients with metastatic disease, such as melanoma and lung cancer. However, only a fraction of patients responds to immunotherapy modalities that target the host immune system. The need to identify new druggable targets that inhibit or prevent metastasis is, therefore, much needed. Tetraspanins have emerged as key players in regulating cell migration, invasion, and metastasis. By serving as molecular adaptors that cluster adhesion receptors, signaling molecules, and cell surface receptors; tetraspanins are involved in all steps of the metastatic cascade. They regulate cell proliferation, participate in EMT transition, modulate integrin-mediated cell adhesion, and participate in angiogenesis and invasion processes. Tetraspanins have also been shown to modulate metastasis indirectly through exosomes and by regulating cellular interactions in the immune system. Importantly, targeting individual tetraspanin with antibodies has impacted tumor progression. This review will focus on the contribution of tetraspanins to the metastatic process and their potential as therapeutic tumor targets.

Significance of PI3K/AKT signaling pathway in metastasis of esophageal squamous cell carcinoma and its potential as a target for anti-metastasis therapy

Metastasis is the most lethal hallmark of esophageal squamous cell carcinoma (ESCC). The aim of the study is to identify key signaling pathways that control metastasis in ESCC. Highly invasive ESCC sublines (designated I3 cells) were established through three rounds of selection of cancer cells invading through matrigel-coated chambers. Gene expression profile of one of the I3 sublines was compared with that of its parental cell line using cDNA microarray analysis. Gene ontology and pathway analyses of the differentially expressed genes (both upregulated and downregulated) indicated that genes associated with cellular movement and the AKT pathway were associated with increased cancer cell invasiveness. Western blot analysis confirmed increased phosphorylated AKT (p-AKT), N-cadherin and decreased E-cadherin expression in the I3 cells. Immunohistochemistry was used to evaluate the clinical significance of p-AKT expression in ESCC, and the results showed higher p-AKT nuclear expression in lymph node metastases when compared with primary carcinoma. Inactivation of the PI3K/AKT pathway with specific inhibitors, or with PTEN overexpression, resulted in reversed cadherin switching and inhibited cancer cell motility. Inhibition of the pathway by treatment with wortmannin markedly suppressed experimental metastasis in nude mice. Our data demonstrated the importance of the PI3K/AKT signaling pathway in ESCC metastasis and support PI3K/AKT as a valid therapeutic target in treatment of metastatic ESCC.

Diselaginellin B, an Unusual Dimeric Molecule from Selaginella pulvinata, Inhibited Metastasis and Induced Apoptosis of SMMC-7721 Human Hepatocellular Carcinoma Cells

Two new unusual dimeric selaginellins, diselaginellins A and B (1 and 2), along with two known derivatives, selaginellin (3) and selaginellin B (4), were isolated from Selaginella pulvinata. Their structures were elucidated by extensive NMR and high-resolution ESIMS data analysis. Compound 2 displayed apoptosis-inducing and antimetastatic activities against the human hepatocellular carcinoma cell line SMMC-7721. A microarray analysis revealed that genes related to metabolism, angiogenesis, and metastasis were altered by 2. The up- and down-regulation of the mRNA levels of related genes was confirmed by RT-qPCR. Metabolism modulation and metastasis inhibition might be the mechanisms of the antitumor properties of diselaginellin B (2).

Tetraspanin 8 (TSPAN 8) as a potential target for radio-immunotherapy of colorectal cancer

Tetraspanin 8 (TSPAN8) overexpression is correlated with poor prognosis in human colorectal cancer (CRC). A murine mAb Ts29.2 specific for human TSPAN8 provided significant efficiency for immunotherapy in CRC pre-clinical models. We therefore evaluate the feasability of targeting TSPAN8 in CRC with radiolabeled Ts29.2. Staining of tissue micro-arrays with Ts29.2 revealed that TSPAN8 espression was restricted to a few human healthy tissues. DOTA-Ts29.2 was radiolabeled with 111In or 177Lu with radiochemical purities >95%, specific activity ranging from 300 to 600 MBq/mg, and radioimmunoreactive fractions >80%. The biodistribution of [111In]DOTA-Ts29.2 in nude mice bearing HT29 or SW480 CRC xenografts showed a high specificity of tumor localization with high tumor/blood ratios (HT29: 4.3; SW480-TSPAN8: 3.9 at 72h and 120h post injection respectively). Tumor-specific absorbed dose calculations for [177Lu]DOTA-Ts29.2 was 1.89 Gy/MBq, establishing the feasibility of using radioimmunotherapy of CRC with this radiolabeled antibody. A significant inhibition of tumor growth in HT29 tumor-bearing mice treated with [177Lu]DOTA-Ts29.2 was observed compared to control groups. Ex vivo experiments revealed specific DNA double strand breaks associated with cell apoptosis in [177Lu]DOTA-Ts29.2 treated tumors compared to controls. Overall, we provide a proof-of-concept for the use of [111In/177Lu]DOTA-Ts29.2 that specifically target in vivo aggressive TSPAN8-positive cells in CRC.

Joint features and complementarities of Tspan8 and CD151 revealed in knockdown and knockout models

Tetraspanins are highly conserved 4-transmembrane proteins which form molecular clusters with a large variety of transmembrane and cytosolic proteins. By these associations tetraspanins are engaged in a multitude of biological processes. Furthermore, tetraspanin complexes are located in specialized microdomains, called tetraspanin-enriched microdomains (TEMs). TEMs provide a signaling platform and are poised for invagination and vesicle formation. These vesicles can be released as exosomes (Exo) and are important in cell contact-independent intercellular communication. Here, we summarize emphasizing knockdown and knockout models' pathophysiological joint and selective activities of CD151 and Tspan8, and discuss the TEM-related engagement of CD151 and Tspan8 in Exo activities.