BMX-ARHGAP fusion protein maintains the tumorigenicity of gastric cancer stem cells by activating the JAK/STAT3 signaling pathway

Oncogenic fusion of CD63-BCAR4 contributes cancer stem cell-like properties via ALDH1 activity

Gene fusions are common somatic alterations in cancers, and fusions with tumorigenic features have been identified as novel drivers of cancer and therapeutic targets. Few studies have determined whether the oncogenic ability of fusion genes is related to the induction of stemness in cells. Cancer stem cells (CSCs) are a subset of cells that contribute to cancer progression, metastasis, and recurrence, and are critical components of the aggressive features of cancer. Here, we investigated the CSC-like properties induced by CD63-BCAR4 fusion gene, previously reported as an oncogenic fusion, and its potential contribution for the enhanced metastasis as a notable characteristic of CD63-BCAR4. CD63-BCAR4 overexpression facilitates sphere formation in immortalized bronchial epithelial cells. The significantly enhanced sphere-forming activity observed in tumor-derived cells from xenografted mice of CD63-BCAR4 overexpressing cells was suppressed by silencing of BCAR4. RNA microarray analysis revealed that ALDH1A1 was upregulated in the BCAR4 fusion-overexpressing cells. Increased activity and expression of ALDH1A1 were observed in the spheres of CD63-BCAR4 overexpressing cells compared with those of the empty vector. CD133 and CD44 levels were also elevated in BCAR4 fusion-overexpressing cells. Increased NANOG, SOX2, and OCT-3/4 protein levels were observed in metastatic tumor cells derived from mice injected with CD63-BCAR4 overexpressing cells. Moreover, DEAB, an ALDH1A1 inhibitor, reduced the migration activity induced by CD63-BCAR4 as well as the sphere-forming activity. Our findings suggest that CD63-BCAR4 fusion induces CSC-like properties by upregulating ALDH1A1, which contributes to its metastatic features.

Overexpression of Glycosyltransferase 8 Domain Containing 1 Promotes Gastric Cancer Proliferation and Inhibits Apoptosis via Mediating PTPN6/JAK2/STAT3 Signaling Axis

Background: The mechanisms of gastric cancer (GC) occurrence and development are still unclear. Although glycosyltransferase 8 domain containing 1 (GLT8D1) has been implicated in GC, its specific role and molecular mechanisms in GC progression need to be further investigated. Methods: Tissue microarrays were used to detect the expression levels of GLT8D1 in 80 GC tissues and their corresponding non-tumor adjacent tissues. The correlations between the GLT8D1 expression level and clinicopathological characteristics were evaluated. A series of in vitro and in vivo functional experiments were performed to explore the role of GLT8D1 in GC progression. Combined with transcriptomic RNA sequencing (RNA-seq) and Weighted Gene Co-expression Network Analysis (WGCNA), we delineated the potential mechanisms via experimental verification. Results: Elevated expression of GLT8D1 in GC tissues was positively correlated with advanced clinical stages and poor prognosis. Konckdown of GLT8D1 significantly inhibited GC cell proliferation and induced apoptosis, whereas overexpression did the opposite. Further researches demonstrated that protein tyrosine phosphatase non-receptor type 6 (PTPN6), a downstream target of GLT8D1, has the capacity to modulate the activity of the JAK2/STAT3 signaling pathway. Conclusions: Our study indicated that GLT8D1 expression was upregulated in GC tissues and correlated with poor prognosis. We reveal a potential molecular mechanism by which GLT8D1 promotes GC progression.

Host protein EPCAM interacting with EtMIC8-EGF is essential for attachment and invasion of Eimeria tenella in chickens

The five epidermal growth factor-like domains (EGF) of Eimeria tenella microneme protein 8 (EtMIC8) (EtMIC8-EGF) plays a vital role in host cell attachment and invasion. These processes require interactions between parasite proteins and receptors on the surface of host cells. In this study, five chicken membrane proteins potentially interacting with EtMIC8-EGF were identified using the GST pull-down assay and mass spectrometry analysis, and only chicken (Gallus gallus) epithelial cell adhesion molecule (EPCAM) could bind to EtMIC8-EGF. EPCAM-specific antibody and recombinant EPCAM protein (rEPCAM) inhibited the EtMIC8-EGF binding to host cells in a concentration-dependent manner. Furthermore, the rEPCAM protein showed a binding activity to sporozoites in vitro, and a significant reduction of E. tenella invasion in DF-1 cells was further observed after pre-incubation of sporozoites with rEPCAM. The specific anti-EPCAM antibody further significantly decreased weight loss, lesion score and oocyst output during E. tenella infection, displaying partial inhibition of E. tenella infection. These results indicate that chicken EPCAM is an important EtMIC8-interacting host protein involved in E. tenella-host cell adhesion and invasion. The findings will contribute to a better understanding of the role of adhesion-associated microneme proteins in E. tenella.

FTO Promotes the Stemness of Gastric Cancer Cells

The full name of the FTO gene is fat mass and obesity-associated gene. In recent years, it has also been found that FTO is involved in m6A demethylation and regulates the progression of multiple cancers, including gastric cancer. The cancer stem cell theory argues that cancer stem cells are key factors in cancer metastasis, and inhibiting the expression of stemness genes is a good method to inhibit metastasis of gastric cancer. Currently, the role of the FTO gene in regulating stemness of gastric cancer cells is still unclear. By analyzing public databases, it was discovered that FTO gene expression was increased in gastric cancer, and high expression of FTO was associated with poor prognosis of patients with gastric cancer. After gastric cancer stem cells were isolated, it was found that FTO protein expression was increased in gastric cancer stem cells; stemness of gastric cancer cells was reduced after the FTO gene knockdown; subcutaneous tumors of nude mice were smaller than those of the control group after FTO knockdown; and stemness of gastric cancer cells was enhanced after FTO was overexpressed by plasmid. By reviewing additional literature and experimental validation, we found that SOX2 may be the factor by which FTO promotes the stemness of gastric cancer cells. Therefore, it was concluded that FTO could promote the stemness of gastric cancer cells, and targeting FTO may be a potential therapeutic approach for patients with metastatic gastric cancer. CTR number: TOP-IACUC-2021-0123.

Tumor Cell-Intrinsic CD96 Mediates Chemoresistance and Cancer Stemness by Regulating Mitochondrial Fatty Acid β-Oxidation

Targeting CD96 that originates in immune cells has shown potential for cancer therapy. However, the role of intrinsic CD96 in solid tumor cells remains unknown. Here, it is found that CD96 is frequently expressed in tumor cells from clinical breast cancer samples and is correlated with poor long-term prognosis in these patients. The CD96⁺ cancer cell subpopulations exhibit features of both breast cancer stem cells and chemoresistance. In vivo inhibition of cancer cell-intrinsic CD96 enhances the chemotherapeutic response in a patient-derived tumor xenograft model. Mechanistically, CD96 enhances mitochondrial fatty acid β-oxidation via the CD155-CD96-Src-Stat3-Opa1 pathway, which subsequently promotes chemoresistance in breast cancer stem cells. A previously unknown role is identified for tumor cell-intrinsic CD96 and an attractive target in improving the chemotherapeutic response.

ARHGAP-RhoA signaling provokes homotypic adhesion-triggered cell death of metastasized diffuse-type gastric cancer

Genetic alteration of Rho GTPase-activating proteins (ARHGAP) and GTPase RhoA is a hallmark of diffuse-type gastric cancer and elucidating its biological significance is critical to comprehensively understanding this malignancy. Here, we report that gene fusions of ARHGAP6/ARHGAP26 are frequent genetic events in peritoneally-metastasized gastric and pancreatic cancer. From the malignant ascites of patients, we established gastric cancer cell lines that spontaneously gain hotspot RHOA mutations or four different ARHGAP6/ARHGAP26 fusions. These alterations critically downregulate RhoA-ROCK-MLC2 signaling, which elicits cell death. Omics and functional analyses revealed that the downstream signaling initiates actin stress fibers and reinforces intercellular junctions via several types of catenin. E-cadherin-centered homotypic adhesion followed by lysosomal membrane permeabilization is a pivotal mechanism in cell death. These findings support the tumor-suppressive nature of ARHGAP-RhoA signaling and might indicate a new avenue of drug discovery against this refractory cancer.

Targeting Gastric Cancer Stem Cells to Enhance Treatment Response

Gastric cancer (GC) was the fourth deadliest cancer in the world in 2020, and about 770,000 people died from GC that year. The death of patients with GC is mainly caused by the metastasis, recurrence, and chemotherapy resistance of GC cells. The cancer stem cell theory defines cancer stem cells (CSCs) as a key factor in the metastasis, recurrence, and chemotherapy resistance of cancer. It considers targeting gastric cancer stem cells (GCSCs) to be an effective method for the treatment of GC. For GCSCs, genes or noncoding RNAs are important regulatory factors. Many experimental studies have found that some drugs can target the stemness of gastric cancer by regulating these genes or noncoding RNAs, which may bring new directions for the clinical treatment of gastric cancer. Therefore, this review mainly discusses related genes or noncoding RNAs in GCSCs and drugs that target its stemness, thereby providing some information for the treatment of GC.

Targeting protein kinases in cancer stem cells

Cancer stem cells (CSCs) are subpopulations of cancer cells within the tumor bulk that have emerged as an attractive therapeutic target for cancer therapy. Accumulating evidence has shown the critical involvement of protein kinase signaling pathways in driving tumor development, cancer relapse, metastasis, and therapeutic resistance. Given that protein kinases are druggable targets for cancer therapy, tremendous efforts are being made to target CSCs with kinase inhibitors. In this review, we summarize the current knowledge and overview of the roles of protein kinases in various signaling pathways in CSC regulation and drug resistance. Furthermore, we provide an update on the preclinical and clinical studies for the use of kinase inhibitors alone or in combination with current therapies for effective cancer therapy. Despite great premises for the use of kinase inhibitors against CSCs, further investigations are needed to evaluate their efficiencies without any adverse effects on normal stem cells.

ErbB4 Is a Potential Key Regulator of the Pathways Activated by NTRK-Fusions in Thyroid Cancer

NTRK gene fusions are drivers of tumorigenesis events that specific Trk-inhibitors can target. Current knowledge of the downstream pathways activated has been previously limited to the pathways of regulator proteins phosphorylated directly by Trk receptors. Here, we aimed to detect genes whose expression is increased in response to the activation of these pathways. We identified and analyzed differentially expressed genes in thyroid cancer samples with NTRK1 or NTRK3 gene fusions, and without any NTRK fusions, versus normal thyroid gland tissues, using data from the Cancer Genome Atlas, the DESeq2 tool, and the Genome Enhancer and geneXplain platforms. Searching for the genes activated only in samples with an NTRK fusion as opposed to those without NTRK fusions, we identified 29 genes involved in nervous system development, including AUTS2, DTNA, ERBB4, FLRT2, FLRT3, RPH3A, and SCN4A. We found that genes regulating the expression of the upregulated genes (i.e., upstream regulators) were enriched in the “signaling by ERBB4” pathway. ERBB4 was also one of three genes encoding master regulators whose expression was increased only in samples with an NTRK fusion. Moreover, the algorithm searching for positive feedback loops for gene promoters and transcription factors (a so-called “walking pathways” algorithm) identified the ErbB4 protein as the key master regulator. ERBB4 upregulation (p-value = 0.004) was confirmed in an independent sample of ETV6-NTRK3-positive FFPE specimens. Thus, ErbB4 is the potential key regulator of the pathways activated by NTRK gene fusions in thyroid cancer. These results are preliminary and require additional biochemical validation.

Fas signaling in adipocytes promotes low-grade inflammation and lung metastasis of colorectal cancer through interaction with Bmx

Obesity is a global public health issue. Obesity-related chronic low-grade inflammation (meta-inflammation) can lead to aberrant adipokine release and promote cardiometabolic diseases and obesity-related tumors. However, the mechanisms involved in the initiation of inflammatory responses in obesity and obesity-related tumors as well as metastasis are not fully understood. In this study, we found that the increased tumor necrosis factor-alpha (TNF-α) in adipocytes promoted the lung metastasis of MC38 colon cancer cells via Fas signaling. The release of TNF-α and interleukin (IL)-6 by Fas signaling in adipocytes was caused by the activation of the nuclear factor-kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) pathways mediated by the interaction of Fas with Bmx, a non-receptor tyrosine kinase. Moreover, the Fas/Bmx complex is involved in the inflammation of adipocytes via Fas at the Tyr189 site and SH2 domain of Bmx. This is the first study to report the interaction between Fas and Bmx in adipocyte inflammation, which may provide clues for the development of potential new treatment strategies for obesity-related diseases.

The impact of fusion genes on cancer stem cells and drug resistance

With ever increasing evidences on the role of fusion genes as the oncogenic protagonists in myriad cancers, it's time to explore if fusion genes can be the next generational drug targets in meeting the current demands of higher drug efficacy. Eliminating cancer stem cells (CSC) has become the current focus; however, we have reached a standstill in drug development owing to the lack of effective strategies to eradicate CSC. We believe that fusion genes could be the novel targets to overcome this limitation. The intriguing feature of fusion genes is that it dominantly impacts every aspect of CSC including self-renewal, differentiation, lineage commitment, tumorigenicity and stemness. Given the clinical success of fusion gene-based drugs in hematological cancers, our attempt to target fusion genes in eradicating CSC can be rewarding. As fusion genes are expressed explicitly in cancer cells, eradicating CSC by targeting fusion genes provides yet an another advantage of negligible patient side effects since normal cells remain unaffected by the drug. We hereby delineate the latest evidences on how fusion genes regulate CSC and drug resistance.

STAM2 knockdown inhibits proliferation, migration, and invasion by affecting the JAK2/STAT3 signaling pathway in gastric cancer

Signal transducing adaptor molecule 2 (STAM2) is a phosphotyrosine protein, which regulates receptor signaling and trafficking of mammalian cells. However, its role in gastric cancer (GC) remains undiscovered. In this study, we aimed to investigate the functions of STAM2 in GC. The mRNA and protein expression levels of STAM2 were measured by quantitative real-time PCR, western blot analysis, and immunohistochemistry. STAM2 was stably silenced in AGS and HGC-27 cells using small interfering RNA. The function of STAM2 in GC cells was further investigated by CCK-8 assay, EdU incorporation assay, flow cytometry, and scratch wound healing and Boyden chamber assays. Additionally, we conducted biological pathway enrichment analysis and rescue assays to explore the effects of STAM2 on JAK/STAT signaling pathway. Our results showed that STAM2 is remarkably highly expressed in GC tissues and cells, and overexpressed STAM2 is correlated with tumor size, advanced tumor node metastasis stage, and poor prognosis. In addition, STAM2 knockdown could significantly inhibit proliferation, block cell cycle, and restrain migration and invasion capabilities of GC cells. Mechanistically, we found that STAM2 knockdown effectively decreased the expressions of MMP2 and MMP9 and the phosphorylation levels of JAK2 and STAT3. Taken together, this study revealed that STAM2 knockdown could suppress malignant process by targeting the JAK2/STAT3 signaling pathway in GC.

Versatile role of curcumin and its derivatives in lung cancer therapy

Lung cancer is a main cause of death all over the world with a high incidence rate. Metastasis into neighboring and distant tissues as well as resistance of cancer cells to chemotherapy demand novel strategies in lung cancer therapy. Curcumin is a naturally occurring nutraceutical compound derived from Curcuma longa (turmeric) that has great pharmacological effects, such as anti-inflammatory, neuroprotective, and antidiabetic. The excellent antitumor activity of curcumin has led to its extensive application in the treatment of various cancers. In the present review, we describe the antitumor activity of curcumin against lung cancer. Curcumin affects different molecular pathways such as vascular endothelial growth factors, nuclear factor-κB (NF-κB), mammalian target of rapamycin, PI3/Akt, microRNAs, and long noncoding RNAs in treatment of lung cancer. Curcumin also can induce autophagy, apoptosis, and cell cycle arrest to reduce the viability and proliferation of lung cancer cells. Notably, curcumin supplementation sensitizes cancer cells to chemotherapy and enhances chemotherapy-mediated apoptosis. Curcumin can elevate the efficacy of radiotherapy in lung cancer therapy by targeting various signaling pathways, such as epidermal growth factor receptor and NF-κB. Curcumin-loaded nanocarriers enhance the bioavailability, cellular uptake, and antitumor activity of curcumin. The aforementioned effects are comprehensively discussed in the current review to further direct studies for applying curcumin in lung cancer therapy.

B7-H3 Regulates Glioma Growth and Cell Invasion Through a JAK2/STAT3/Slug-Dependent Signaling Pathway

Purpose

The aim of this study was to explore the potential role of B7-H3 in malignant glioma progression and identify an innovative approach in clinical glioma therapy.

Methods

The protein expression of B7-H3 in high- and low-grade tumor tissues from glioma patients was assessed by immunohistochemistry. The proliferative and invasive ability of B7-H3-overexpressing or knockout glioma cells was analyzed in vitro and in vivo by CCK-8 assay and an orthotopic mouse glioma model, respectively. Activation of the JAK2/STAT3/Slug signaling pathway and epithelial-mesenchymal transition (EMT) was examined by Western blotting and immunofluorescence. The anticancer effects of napabucasin (NAP) and temozolomide (TMZ) were analyzed in an orthotopic mouse glioma model.

Results

The expression of B7-H3 was higher in high-grade than in low-grade tumor tissues from glioma patients. In line with this, overexpression of B7-H3 enhanced glioma cell proliferation, induced sustained glioma growth, and promoted glioma cell invasion in vitro and in vivo. Moreover, these effects were mediated through the activation of the JAK2/STAT3/Slug signaling pathway in B7-H3 overexpression glioma cells. We also found that B7-H3 induced EMT processes through downregulation of E-cadherin and upregulation of MMP-2/-9 expression, resulting in enhanced invasion of glioma cells. Finally, we show that the combination of NAP and TMZ significantly suppressed glioma growth and glioma cell invasion, both in vitro and in vivo.

Conclusion

B7-H3 overexpression facilitated sustained glioma growth and promoted glioma cell invasion through a JAK2/STAT3/Slug-dependent signaling pathway. Application of the STAT3 inhibitor NAP significantly suppressed glioma growth and invasion, and has potential as a therapeutic strategy for the treatment of glioma.