An integrin beta4-EGFR unit promotes hepatocellular carcinoma lung metastases by enhancing anchorage independence through activation of FAK–AKT pathway

MDFI promotes the proliferation and tolerance to chemotherapy of colorectal cancer cells by binding ITGB4/LAMB3 to activate the AKT signaling pathway

Colorectal cancer (CRC) is one of the most lethal cancers. Single-cell RNA sequencing (scRNA-seq) and protein-protein interactions (PPIs) have enabled the systematic study of CRC. In our research, the activation of the AKT pathway in CRC was analyzed by KEGG using single-cell sequencing data from the GSE144735 dataset. The correlation and PPIs of MDFI and ITGB4/LAMB3 were examined. The results were verified in the TCGA and CCLE and further tested by coimmunoprecipitation experiments. The effect of MDFI on the AKT pathway via ITGB4/LAMB3 was validated by knockdown and lentiviral overexpression experiments. The effect of MDFI on oxaliplatin/fluorouracil sensitivity was probed by colony formation assay and CCK8 assay. We discovered that MDFI was positively associated with ITGB4/LAMB3. In addition, MDFI was negatively associated with oxaliplatin/fluorouracil sensitivity. MDFI upregulated the AKT pathway by directly interacting with LAMB3 and ITGB4 in CRC cells, and enhanced the proliferation of CRC cells via the AKT pathway. Finally, MDFI reduced the sensitivity of CRC cells to oxaliplatin and fluorouracil. In conclusion, MDFI promotes the proliferation and tolerance to chemotherapy of colorectal cancer cells, partially through the activation of the AKT signaling pathway by the binding to ITGB4/LAMB3. Our findings provide a possible molecular target for CRC therapy.

Machine learning-based identification of biomarkers and drugs in immunologically cold and hot pancreatic adenocarcinomas

BACKGROUND

Pancreatic adenocarcinomas (PAADs) often exhibit a "cold" or immunosuppressive tumor milieu, which is associated with resistance to immune checkpoint blockade therapy; however, the underlying mechanisms are incompletely understood. Here, we aimed to improve our understanding of the molecular mechanisms occurring in the tumor microenvironment and to identify biomarkers, therapeutic targets, and potential drugs to improve PAAD treatment.

METHODS

Patients were categorized according to immunologically hot or cold PAAD subtypes with distinct disease outcomes. Cox regression and weighted correlation network analysis were performed to construct a novel gene signature, referred to as 'Downregulated in hot tumors, Prognostic, and Immune-Related Genes' (DPIRGs), which was used to develop prognostic models for PAAD via machine learning (ML). The role of DPIRGs in PAAD was comprehensively analyzed, and biomarker genes able to distinguish PAAD immune subtypes and predict prognosis were identified by ML. The expression of biomarkers was verified using public single-cell transcriptomic and proteomic resources. Drug candidates for turning cold tumors hot and corresponding target proteins were identified via molecular docking studies.

RESULTS

Using the DPIRG signature as input data, a combination of survival random forest and partial least squares regression Cox was selected from 137 ML combinations to construct an optimized PAAD prognostic model. The effects and molecular mechanisms of DPIRGs were investigated by analysis of genetic/epigenetic alterations, immune infiltration, pathway enrichment, and miRNA regulation. Biomarkers and potential therapeutic targets, including PLEC, TRPV1, and ITGB4, among others, were identified, and the cell type-specific expression of the biomarkers was validated. Drug candidates, including thalidomide, SB-431542, and bleomycin A2, were identified based on their ability to modulate DPIRG expression favorably.

CONCLUSIONS

By combining multiple ML algorithms, we developed a novel prognostic model with excellent performance in PAAD cohorts. ML also proved to be powerful for identifying biomarkers and potential targets for improved PAAD patient stratification and immunotherapy.

Muscone restores anoikis sensitivity in TMZ-resistant glioblastoma cells by suppressing TOP2A via the EGFR/Integrin β1/FAK signaling pathway

BACKGROUND

Temozolomide (TMZ) resistance is the main obstacle faced by glioblastoma multiforme (GBM) treatment. Muscone, one of the primary active pharmacological ingredients of Shexiang (Moschus), can cross the blood-brain barrier (BBB) and is being investigated as an antineoplastic medication. However, muscone treatment for GBM has received little research, and its possible mechanisms are still unclear.

PURPOSE

This study aims to evaluate the effect and the potential molecular mechanism of muscone on TMZ-resistant GBM cells.

METHODS

The differentially expressed genes (DEGs) between TMZ-resistant GBM cells and TMZ-sensitive GBM cells were screened using GEO2R. By progressively raising the TMZ concentration, a relatively stable TMZ-resistant human GBM cell line was established. The drug-resistance traits of U251-TR cells were assessed via the CCK-8 assay and Western Blot analysis of MGMT and TOP2A expression. Cell viability, cell proliferation, cell migration ability, and drug synergism were detected by the CCK-8 assay, colony formation assay, wound healing assay, and drug interaction relationship test, respectively. Anoikis was quantified by Calcein-AM/EthD-1 staining, MTT assay, and flow cytometry. Measurements of cell cycle arrest, apoptosis, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) were performed using cell cycle staining, Annexin V-FITC/PI labeling, JC-1 assay, and ROS assay, respectively. DNA damage was measured by TUNEL assay, alkaline comet assay, and γ-H2AX foci assay. GEPIA was used to investigate the link between the anoikis marker (FAK)/drug resistance gene and critical proteins in the EGFR/Integrin β1 signaling pathway. Molecular docking was used to anticipate the probable targets of muscone. The intracellular co-localization and expression of EGFR and FAK were shown using immunofluorescence. The U251-TR cell line stably overexpressing EGFR was constructed using lentiviral transduction to assess the involvement of EGFR-related signaling in anoikis resistance. Western Blot was employed to detect the expression of migration-related proteins, cyclins, anoikis-related proteins, DNA damage/repair-related proteins, and associated pathway proteins.

RESULTS

DEGs analysis identified 97 deregulated chemotherapy-resistant genes and 3779 upregulated genes in TMZ-resistant GBM cells. Subsequent experiments verified TMZ resistance and the hyper-expression of DNA repair-related genes (TOP2A and MGMT) in continuously low-dose TMZ-induced U251-TR cells. Muscone exhibited dose-dependent inhibition of U251-TR cell migration and proliferation, and its co-administration with TMZ showed the potential for enhanced therapeutic efficacy. By downregulating FAK, muscone reduced anoikis resistance in anchorage-independent U251-TR cells. It also caused cell cycle arrest in the G2/M phase by upregulating p21 and downregulating CDK1, CDK2, and Cyclin E1. Muscone-induced anoikis was accompanied by mitochondrial membrane potential collapse, ROS production, an increase in the BAX/Bcl-2 ratio, as well as elevated levels of Cytochrome c (Cyt c), cleaved caspase-9, and cleaved caspase-3. These findings indicated that muscone might trigger mitochondrial-dependent anoikis via ROS generation. Moreover, significant DNA damage, DNA double-strand breaks (DSBs), the formation of γ-H2AX foci, and a reduction in TOP2A expression are also associated with muscone-induced anoikis. Overexpression of EGFR in U251-TR cells boosted the expression of Integrin β1, FAK, β-Catenin, and TOP2A, whereas muscone suppressed the expression levels of EGFR, Integrin β1, β-Catenin, FAK, and TOP2A. Muscone may influence the expression of the key DNA repair enzyme, TOP2A, by suppressing the EGFR/Integrin β1/FAK pathway.

CONCLUSION

We first demonstrated that muscone suppressed TOP2A expression through the EGFR/Integrin β1/FAK pathway, hence restoring anoikis sensitivity in TMZ-resistant GBM cells. These data suggest that muscone may be a promising co-therapeutic agent for enhancing GBM treatment, particularly in cases of TMZ-resistant GBM with elevated TOP2A expression.

Targeting anoikis resistance as a strategy for cancer therapy

Anoikis, known as matrix detachment-induced apoptosis or detachment-induced cell death, is crucial for tissue development and homeostasis. Cancer cells develop means to evade anoikis, e.g. anoikis resistance, thereby allowing for cells to survive under anchorage-independent conditions. Uncovering the mechanisms of anoikis resistance will provide details about cancer metastasis, and potential strategies against cancer cell dissemination and metastasis. Here, we summarize the principal elements and core molecular mechanisms of anoikis and anoikis resistance. We discuss the latest progress of how anoikis and anoikis resistance are regulated in cancers. Furthermore, we summarize emerging data on selective compounds and nanomedicines, explaining how inhibiting anoikis resistance can serve as a meaningful treatment modality against cancers. Finally, we discuss the key limitations of this therapeutic paradigm and possible strategies to overcome them. In this review, we suggest that pharmacological modulation of anoikis and anoikis resistance by bioactive compounds could surmount anoikis resistance, highlighting a promising therapeutic regimen that could be used to overcome anoikis resistance in cancers.

Pharmacologically inducing anoikis offers novel therapeutic opportunities in hepatocellular carcinoma

Tumor metastasis occurs in hepatocellular carcinoma (HCC), leading to tumor progression and therapeutic failure. Anoikis is a matrix detachment-induced apoptosis, also known as detachment-induced cell death, and mechanistically prevents tumor cells from escaping their native extracellular matrix to metastasize to new organs. Deciphering the regulators and mechanisms of anoikis in cancer metastasis is urgently needed to treat HCC. Several natural and synthetic products induce anoikis in HCC cells and in vivo models. Here, we first briefly summarize the current understanding of the molecular mechanisms of anoikis regulation and relevant regulators involved in HCC metastasis. Then we discuss the therapeutic potential of pharmacological induction of anoikis as a potential treatment against HCC. Finally, we discuss the key limitations of this therapeutic paradigm and propose possible strategies to overcome them. Cumulatively this review suggests that the pharmacological induction of anoikis can be used a promising therapeutic modality against HCC.

Tumour cell-expressed PD-L1 reprograms lipid metabolism via EGFR/ITGB4/SREBP1c signalling in liver cancer

Background & Aims

The programmed death-ligand 1 (PD-L1) is a major co-inhibitory checkpoint factor that controls T-cell activities in tumours. PD-L1 is expressed on immune cells and tumour cells. Whether tumour cell-expressed PD-L1 affects tumour cells in an immune cell-independent fashion remains largely elusive. In this study, we investigated the significance of tumour cell-expressed PD-L1 with a focus on downstream signals and changes in lipid metabolism.

Methods

Immune-independent functions of PD-L1 in tumour growth were investigated in vitro and in immuno-deficient mice in vivo. The global influence of PD-L1 in targeted/untargeted lipidomic metabolites was studied by comprehensive mass spectrometry-based metabolomic analysis in liver cancer. Effects on lipid metabolism were confirmed by triglyceride and cholesterol assays as well as by Oil Red O staining in liver, pancreatic, breast, and oesophageal squamous cancer. Underlying mechanisms were investigated by real-time quantitative PCR, Western blot analysis, co-immunoprecipitation, pull-down assays, immunofluorescence staining, and RNA sequencing.

Results

PD-L1 enhanced the accumulation of triglycerides, cholesterol, and lipid droplets in tumours. PD-L1 influenced targeted/untargeted lipidomic metabolites in hepatoma, including lipid metabolism, glucose metabolism, amino acid metabolism, nucleotide metabolism, and energy metabolism, suggesting that PD-L1 globally modulates the metabolic reprogramming of tumours. Mechanistically, PD-L1 activated epidermal growth factor receptor (EGFR) and/or integrin β4 (ITGB4) by forming a complex of PD-L1/EGFR/ITGB4 in the cell membrane, prior to activating PI3K/mTOR/SREBP1c signalling, leading to reprogramming of lipid metabolism in tumours. Functionally, PD-L1-mediated lipid metabolism reprogramming supported the tumour growth in vitro and in vivo through EGFR and/or ITGB4 in an immune cell-independent manner.

Conclusions

Our findings on lipogenesis and EGFR activation by tumour cell-expressed PD-L1 suggest that, in addition to its immunostimulatory effects, anti-PD-L1 may restrict lipid metabolism and EGFR/ITGB4 signalling in liver cancer therapy.

Impact and implications

In this study, we present evidence that PD-L1 drives the reprogramming of lipid metabolism in tumours. PD-L1 forms a complex with epidermal growth factor receptor (EGFR) and ITGB4, activating the PI3K/Akt/mTOR/SREBP1c signalling pathway and thereby contributing to lipid metabolism in cancer progression. Our findings offer novel insights into the mechanisms by which PD-L1 initiates the reprogramming of lipid metabolism in tumours. From a clinical perspective, the anti-PD-L1 antibody may alleviate resistance to the anti-EGFR antibody cetuximab and inhibit the reprogramming of lipid metabolism in tumours.

Knockdown of ribosome RNA processing protein 15 suppresses migration of hepatocellular carcinoma through inhibiting PATZ1-associated LAMC2/FAK pathway

BACKGROUND

Ribosomal RNA processing protein 15 (RRP15) has been found to regulate the progression of hepatocellular carcinoma (HCC). Nevertheless, the extent to which it contributes to the spread of HCC cells remains uncertain. Thus, the objective of this research was to assess the biological function of RRP15 in the migration of HCC.

METHODS

The expression of RRP15 in HCC tissue microarray (TMA), tumor tissues and cell lines were determined. In vitro, the effects of RRP15 knockdown on the migration, invasion and adhesion ability of HCC cells were assessed by wound healing assay, transwell and adhesion assay, respectively. The effect of RRP15 knockdown on HCC migration was also evaluated in vivo in a mouse model.

RESULTS

Bioinformatics analysis showed that high expression of RRP15 was significantly associated with low survival rate of HCC. The expression level of RRP15 was strikingly upregulated in HCC tissues and cell lines compared with the corresponding controls, and TMA data also indicated that RRP15 was a pivotal prognostic factor for HCC. RRP15 knockdown in HCC cells reduced epithelial-to-mesenchymal transition (EMT) and inhibited migration in vitro and in vivo, independent of P53 expression. Mechanistically, blockade of RRP15 reduced the protein level of the transcription factor POZ/BTB and AT hook containing zinc finger 1 (PATZ1), resulting in decreased expression of the downstream genes encoding laminin 5 subunits, LAMC2 and LAMB3, eventually suppressing the integrin β4 (ITGB4)/focal adhesion kinase (FAK)/nuclear factor κB kappa-light-chain-enhancer of activated B cells (NF-κB) signaling pathway.

CONCLUSIONS

RRP15 promotes HCC migration by activating the LAMC2/ITGB4/FAK pathway, providing a new target for future HCC treatment.

Exosome-transmitted FOSL1 from cancer-associated fibroblasts drives colorectal cancer stemness and chemo-resistance through transcriptionally activating ITGB4

Cancer-associated fibroblasts (CAFs) have been proved to facilitate colorectal cancer (CRC) development, either with boosting chemo-resistance by communicating with CRC cells in the tumor microenvironment. However, the underlying molecular mechanisms remain largely unclear. Relative expressions of FOSL1 and ITGB4, either with their correlations in CRC tissues, were assessed using qRT-PCR analysis. Also, Kaplan-Meier survival analysis was employed for evaluating the prognosis. Identification of CAFs was determined by the detection of specific makers (α-SMA, FAP, and FSP1) using western blot and immunofluorescence staining. Cell proliferation, self-renewal capacity, and cell apoptosis were estimated by CCK-8, sphere-formation, and flow cytometry assays. Transcriptional regulation of FOSL1 on integrin β4 (ITGB4) was confirmed using ChIP and dual-luciferase reporter assays. Increased FOSL1 and ITGB4 in CRC tissues were both positively correlated with the poor prognosis of CRC patients. Interestingly, FOSL1 was enriched in the CAFs isolated from CRC stroma, instead of ITGB4. CRC cells under a co-culture system with CAFs-conditioned medium (CAFs-CM) exhibited increased FOSL1, promotive cell proliferation, and reduced apoptosis, while these effects could be blocked by exosome inhibitor (GW4869). Moreover, CAFs-derived exosomal FOSL1 was validated to enhance proliferative ability and oxaliplatin resistance of CRC cells. Our results uncovered that CAFs-derived exosomes could transfer FOSL1 to CRC cells, thereby promoting CRC cell proliferation, stemness, and oxaliplatin resistance by transcriptionally activating ITGB4.

Integrin β4 Regulates Cell Migration of Lung Adenocarcinoma Through FAK Signaling

The role of the integrin family in malignancy has received increasing attention. Many studies have confirmed that ITGB4 could activate multiple signal pathways and promote cell migration in various cancers. However, the regulatory role of integrin β4 (ITGB4) in lung adenocarcinoma (LUAD) is still unclear. Examination of the expression or survival analysis of ITGB4 in cells, pathological samples, and bioinformatics lung adenocarcinoma databases showed ITGB4 was highly expressed in LUAD and significantly associated with poor prognosis. Small interfering RNA and plasmids were performed to investigate the effect of changes in ITGB4 expression on lung adenocarcinoma. Focal adhesion kinase (FAK) inhibitor defactinib was used to further explore the molecular mechanism of ITGB4. The results showed depletion of ITGB4 inhibited migration and activation of FAK signaling pathways in lung adenocarcinoma cells. Moreover, increased ITGB4 expression activated FAK signaling and promoted cell migration, which can be reversed by defactinib. In addition, ITGB4 could interact with FAK in lung adenocarcinoma cells. ITGB4 may promote cell migration of lung adenocarcinoma through FAK signaling pathway and has the potential to be a biomarker for lung adenocarcinoma.

Hypoxia inducible factor-1ɑ as a potential therapeutic target for osteosarcoma metastasis

Osteosarcoma (OS) is a malignant tumor originating from mesenchymal tissue. Pulmonary metastasis is usually present upon initial diagnosis, and metastasis is the primary factor affecting the poor prognosis of patients with OS. Current research shows that the ability to regulate the cellular microenvironment is essential for preventing the distant metastasis of OS, and anoxic microenvironments are important features of solid tumors. During hypoxia, hypoxia-inducible factor-1α (HIF-1α) expression levels and stability increase. Increased HIF-1α promotes tumor vascular remodeling, epithelial-mesenchymal transformation (EMT), and OS cells invasiveness; this leads to distant metastasis of OS cells. HIF-1α plays an essential role in the mechanisms of OS metastasis. In order to develop precise prognostic indicators and potential therapeutic targets for OS treatment, this review examines the molecular mechanisms of HIF-1α in the distant metastasis of OS cells; the signal transduction pathways mediated by HIF-1α are also discussed.

The expression of VEGF and cyclin D1/EGFR in common primary liver carcinomas in Egypt: an immunohistochemical study

Background

The most common types of primary malignant liver tumours are hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). Treatment options for patients who are inoperable/advanced, or recurring are challenging. Cyclin D1, epidermal growth factor (EGFR) and vascular endothelial growth factor (VEGR) are common carcinogenic proteins that have potential therapeutic targets in various cancers. They have been implicated in the development of HCC and CCA. In this study, we aimed to evaluate the oncogenic function expression of cyclin D1, EGFR and VEGF in HCC and CCA of Egyptian patients. This could help to validate their therapeutic potential.

Material and methods

Tumour cases were selected from 82 cases of primary liver carcinomas, with 58 cases being from HCC and 24 cases from CCA compared to 51 non-tumour adjacent liver cases and 18 from normal liver tissue. The immunohistochemical study of cyclin D1, EGFR and VEGR was conducted.

Results

Cyclin D1, EGFR and VEGF are overexpressed in HCC and CCA as compared to the control group (p < 0.001). Cyclin D1 was related to well-differentiated grade and early pathologic stage in HCC (p = 0.016 and p = 0.042, respectively). The well-differentiated grade showed significantly higher VEGF levels (p = 0.04). In the CCA group, however, EGFR was strongly related to high tumour size (p = 0.047). EGFR and VEGF were overexpressed in HCC raised in the non-cirrhotic liver compared to those developed in post-hepatitic liver cirrhosis (p = 0.003 and p = 0.014).

Conclusion

Cyclin D1, EGFR and VEGF shared significant overexpression in HCC and CCA. EGFR and VEGF may play an oncogenic function in the development of HCC in non-cirrhotic liver. Furthermore, cyclin D1 and VEGF may play a good prognostic function in HCC, but EGFR may play a bad prognostic role in CCA.

ITGB4 Serves as an Identification and Prognosis Marker Associated with Immune Infiltration in Small Cell Lung Carcinoma

Integrin beta 4 (ITGB4) is a vital factor for numerous cancers. However, no reports regarding ITGB4 in small cell lung carcinoma (SCLC) have been found in the existing literature. This study systematically investigated the expression and clinical value of ITGB4 in SCLC using multi-center and large-sample (n = 963) data. The ITGB4 expression levels between SCLC and control tissues were compared using standardized mean difference and Wilcoxon rank-sum test. The clinical significance of the gene in SCLC was observed using Cox regression and Kaplan-Meier curves. ITGB4 is overexpressed in multiple cancers and represents significant value in distinguishing among cancer samples (AUC = 0.91) and predicting the prognoses (p < 0.05) of patients with different cancers. In contrast, decreased ITGB4 mRNA expression was determined in SCLC (SMD < 0), and this finding was further confirmed at protein levels using in-house specimens (p < 0.05). This decrease in expression may be attributed to the regulatory role of estrogen receptor 1. ITGB4 may participate in the progression of SCLC by affecting several signaling pathways (e.g., tumor necrosis factor signaling pathway) and a series of immune cells (e.g., dendritic cells) (p < 0.05). The gene may serve as a potential marker for predicting the disease status (AUC = 0.97) and prognoses (p < 0.05) of patients with SCLC. Collectively, ITGB4 was identified as an identification and prognosis marker associated with immune infiltration in SCLC.

Integrin β4 induced epithelial-to-mesenchymal transition involves miR-383 mediated regulation of GATA6 levels

BACKGROUND

The process of transdifferentiating epithelial cells to mesenchymal-like cells (EMT) involves cells gradually taking on an invasive and migratory phenotype. Many cell adhesion molecules are crucial for the management of EMT, integrin β4 (ITGB4) being one among them. Although signaling downstream of ITGB4 has been reported to cause changes in the expression of several miRNAs, little is known about the role of such miRNAs in the process of EMT.

METHODS AND RESULTS

The cytoplasmic domain of ITGB4 (ITGB4CD) was ectopically expressed in HeLa cells to induce ITGB4 signaling, and expression analysis of mesenchymal markers indicated the induction of EMT. β-catenin and AKT signaling pathways were found to be activated downstream of ITGB4 signaling, as evidenced by the TOPFlash assay and the levels of phosphorylated AKT, respectively. Based on in silico and qRT-PCR analysis, miR-383 was selected for functional validation studies. miR-383 and Sponge were ectopically expressed in HeLa, thereafter, western blot and qRT-PCR analysis revealed that miR-383 regulates GATA binding protein 6 (GATA6) post-transcriptionally. The ectopic expression of shRNA targeting GATA6 caused the reversal of EMT and β catenin activation downstream of ITGB4 signaling. Cell migration assays revealed significantly high cell migration upon ectopic expression ITGB4CD, which was reversed upon ectopic co-expression of miR-383 or GATA6 shRNA. Besides, ITGB4CD promoted EMT in in ovo xenograft model, which was reversed by ectopic expression of miR-383 or GATA6 shRNA.

CONCLUSION

The induction of EMT downstream of ITGB4 involves a signaling axis encompassing AKT/miR-383/GATA6/β-catenin.

A Signature Constructed Based on the Integrin Family Predicts Prognosis and Correlates with the Tumor Microenvironment of Patients with Lung Adenocarcinoma

As an important element in regulating the tumor microenvironment (TME), integrin plays a key role in tumor progression. This study aimed to establish prognostic signatures to predict the overall survival and identify the immune landscape of patients with lung adenocarcinoma based on integrins. The Cancer Genome Atlas-Lung Adenocarcinoma (TCGA-LUAD) and Gene Expression Omnibus datasets were used to obtain information on mRNA levels and clinical factors (GSE72094). The least absolute shrinkage and selection operator (LASSO) model was used to create a prediction model that included six integrin genes. The nomogram, risk score, and time-dependent receiver operating characteristic analysis all revealed that the signatures had a good prognostic value. The gene signatures may be linked to carcinogenesis and TME, according to a gene set enrichment analysis. The immunological and stromal scores were computed using the ESTIMATE algorithm, and the data revealed, the low-risk group had a higher score. We discovered that the B lymphocytes, plasma, CD4+ T, dendritic, and mast cells were much higher in the group with low-risk using the CiberSort. Inflammatory processes and several HLA family genes were upregulated in the low-risk group. The low-risk group with a better prognosis is more sensitive to immune checkpoint inhibitor medication, according to immunophenoscore (IPS) research. We found that the patients in the high-risk group were more susceptible to chemotherapy than other group patients, according to the prophetic algorithm. The gene signatures could accurately predict the prognosis, identify the immune status of patients with lung adenocarcinoma, and provide guidance for therapy.

Integrins in human hepatocellular carcinoma tumorigenesis and therapy

ABSTRACT

Integrins are a family of transmembrane receptors that connect the extracellular matrix and actin skeleton, which mediate cell adhesion, migration, signal transduction, and gene transcription. As a bi-directional signaling molecule, integrins can modulate many aspects of tumorigenesis, including tumor growth, invasion, angiogenesis, metastasis, and therapeutic resistance. Therefore, integrins have a great potential as antitumor therapeutic targets. In this review, we summarize the recent reports of integrins in human hepatocellular carcinoma (HCC), focusing on the abnormal expression, activation, and signaling of integrins in cancer cells as well as their roles in other cells in the tumor microenvironment. We also discuss the regulation and functions of integrins in hepatitis B virus-related HCC. Finally, we update the clinical and preclinical studies of integrin-related drugs in the treatment of HCC.

The Association of Integrins β3, β4, and αVβ5 on Exosomes, CTCs and Tumor Cells with Localization of Distant Metastasis in Breast Cancer Patients

Integrins are cell adhesion receptors, which play a role in breast cancer invasion, angiogenesis, and metastasis. Moreover, it has been shown that exosomal integrins provide organotropic metastasis in a mouse model. In our study, we aimed to investigate the expression of integrins β3, β4, and αVβ5 on exosomes and tumor cells (circulating tumor cells and primary tumor) and their association with the localization of distant metastasis. We confirmed the association of exosomal integrin β4 with lung metastasis in breast cancer patients. However, we were unable to evaluate the role of integrin β3 in brain metastasis due to the rarity of this localization. We established no association of exosomal integrin αVβ5 with liver metastasis in our cohort of breast cancer patients. The further evaluation of β3, β4, and αVβ5 integrin expression on CTCs revealed an association of integrin β4 and αVβ5 with liver, but not the lung metastases. Integrin β4 in the primary tumor was associated with liver metastasis. Furthermore, an in-depth analysis of phenotypic characteristics of β4+ tumor cells revealed a significantly increased proportion of E-cadherin+ and CD44+CD24- cells in patients with liver metastases compared to patients with lung or no distant metastases.

ITGB4 deficiency in airway epithelia enhances HDM-induced airway inflammation through hyperactivation of TLR4 signaling pathway

Airway epithelial cells (AECs) are the first cell barrier of the respiratory system against external stimuli that play a critical role in the development of asthma. It is known that AECs play a key role in asthma susceptibility and severity. ITGB4 is a downregulated adhesion molecule in the airway epithelia of asthma patients, which was involved in the exaggerated lung inflammation after allergy stimulation. Toll-like receptor 4 (TLR4) in AECs has also been shown to play a crucial role in the development of lung inflammation in asthma patients. However, the specific intrinsic regulatory mechanism of TLR4 in AECs are still obscure. In this article, we demonstrated that ITGB4 deficiency in AECs enhances HDM-induced airway inflammation through hyperactivation of the TLR4 signaling pathway, which is mediated by inhibition of FYN phosphorylation. Moreover, TLR4-antagonist treatment or blockade of FYN can inhibit or exaggerate lung inflammation in HDM-stressed ITGB4-deficient mice, separately. Together, these results demonstrated that ITGB4 deficiency in AECs enhances HDM-induced lung inflammatory response through the ITGB4-FYN-TLR4 axis, which may provide new therapeutic approaches for the management of lung inflammation in asthma.

Identification of a novel anoikis-related gene signature to predict prognosis and tumor microenvironment in lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD) is the most prevalent histotype of non-small cell lung cancer. Anoikis, an alternative form of programmed cell death, plays a pivotal role in cancer invasion and metastasis, preventing the detached cancer cells from readhering to other substrates for abnormal proliferation. The aim of this study was to conduct a comprehensive analyses of the prognostic implications of anoikis-related genes (ARGs) in LUAD.

METHODS

ARGs were selected from The Cancer Genome Atlas (TCGA) database and Genecards dataset using differential expression analysis. The signature incorporating ARGs was identified using univariate Cox regression analysis and LASSO regression analysis. Furthermore, a nomogram containing the signature and clinical information was developed through univariate and multivariate Cox regression analysis. Kaplan-Meier survival analysis and receiver operating characteristic (ROC) curves were applied to evaluate the predictive validity of these risk models. Finally, functional analysis of the selected ARGs in signature and analysis of immune landscape were also conducted.

RESULTS

A 16-gene signature was integrated to stratify LUAD patients into different survival risk groups. The prognostic risk score generated from the signature and TNM stage were identified as independent prognostic factors and utilized to develop a nomogram. Both the signature and the nomogram showed satisfactory prediction performance in predicting overall survival (OS) of LUAD patients. The ARGs were enriched in several biological functions and signaling pathways. Finally, differences of immune landscape were investigated among the high- and low-risk groups stratified by the signature.

CONCLUSIONS

This study revealed potential relationships between ARGs and prognosis of LUAD. The prognostic predictors identified in present study could be utilized as potential biomarkers for clinical applications.

OCT6 inhibits differentiation of porcine-induced pluripotent stem cells through MAPK and PI3K signaling regulation

As a transcription factor of the Pit-Oct-Unc (POU) domain family, octamer-binding transcription factor 6 ( OCT6) participates in various aspects of stem cell development and differentiation. At present, however, its role in porcine-induced pluripotent stem cells (piPSCs) remains unclear. Here, we explored the function of OCT6 in piPSCs. We found that piPSCs overexpressing OCT6 maintained colony morphology and pluripotency under differentiation conditions, with a similar gene expression pattern to that of non-differentiated piPSCs. Functional analysis revealed that OCT6 attenuated the adverse effects of extracellular signal-regulated kinase (ERK) signaling pathway inhibition on piPSC pluripotency by activating phosphatidylinositol 3-kinase-protein kinase B (PI3K-AKT) signaling activity. Our research sheds new light on the mechanism by which OCT6 promotes PSC maintenance.

Investigation of Anti-Liver Cancer Activity of the Herbal Drug FDY003 Using Network Pharmacology

Globally, liver cancer (LC) is the sixth-most frequently occurring and the second-most fatal malignancy, responsible for 0.83 million deaths annually. Although the application of herbal drugs in cancer therapies has increased, their anti-LC activity and relevant mechanisms have not been fully studied from a systems perspective. To address these issues, we conducted a system-perspective network pharmacological investigation into the activity and mechanisms underlying the action of the herbal drug. FDY003 reduced the viability of human LC treatment. FDY003 reduced the viability of human LC cells and elevated their chemosensitivity. There were a total of 16 potential bioactive chemical components in FDY003 and they had 91 corresponding targets responsible for the pathological processes in LC. These FDY003 targets were functionally involved in regulating the survival, proliferation, apoptosis, and cell cycle of LC cells. Additionally, we found that FDY003 may target key signaling cascades connected to diverse LC pathological mechanisms, namely, PI3K-Akt, focal adhesion, IL-17, FoxO, MAPK, and TNF pathways. Overall, this study contributed to integrative mechanistic insights into the anti-LC potential of FDY003.

A transcriptomic map of EGFR-induced epithelial-to-mesenchymal transition identifies prognostic and therapeutic targets for head and neck cancer

Background

Epidermal growth factor receptor (EGFR) is both a driver oncogene and a therapeutic target in advanced head and neck squamous cell carcinoma (HNSCC). However, response to EGFR treatment is inconsistent and lacks markers for treatment prediction. This study investigated EGFR-induced epithelial-to-mesenchymal transition (EMT) as a central parameter in tumor progression and identified novel prognostic and therapeutic targets, and a candidate predictive marker for EGFR therapy response.

Methods

Transcriptomic profiles were analyzed by RNA sequencing (RNA-seq) following EGFR-mediated EMT in responsive human HNSCC cell lines. Exclusive genes were extracted via differentially expressed genes (DEGs) and a risk score was determined through forward feature selection and Cox regression models in HNSCC cohorts. Functional characterization of selected prognostic genes was conducted in 2D and 3D cellular models, and findings were validated by immunohistochemistry in primary HNSCC.

Results

An EGFR-mediated EMT gene signature composed of n = 171 genes was identified in responsive cell lines and transferred to the TCGA-HNSCC cohort. A 5-gene risk score comprising DDIT4, FADD, ITGB4, NCEH1, and TIMP1 prognosticated overall survival (OS) in TCGA and was confirmed in independent HNSCC cohorts. The EGFR-mediated EMT signature was distinct from EMT hallmark and partial EMT (pEMT) meta-programs with a differing enrichment pattern in single malignant cells. Molecular characterization showed that ITGB4 was upregulated in primary tumors and metastases compared to normal mucosa and correlated with EGFR/MAPK activity in tumor bulk and single malignant cells. Preferential localization of ITGB4 together with its ligand laminin 5 at tumor-stroma interfaces correlated with increased tumor budding in primary HNSCC tissue sections. In vitro, ITGB4 knock-down reduced EGFR-mediated migration and invasion and ITGB4-antagonizing antibody ASC8 impaired 2D and 3D invasion. Furthermore, a logistic regression model defined ITGB4 as a predictive marker of progression-free survival in response to Cetuximab in recurrent metastatic HNSCC patients.

Conclusions

EGFR-mediated EMT conveyed through MAPK activation contributes to HNSCC progression upon induction of migration and invasion. A 5-gene risk score based on a novel EGFR-mediated EMT signature prognosticated survival of HNSCC patients and determined ITGB4 as potential therapeutic and predictive target in patients with strong EGFR-mediated EMT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01646-1.

KRAS Mutants Upregulate Integrin β4 to Promote Invasion and Metastasis in Colorectal Cancer

KRAS mutation in colorectal cancer is associated with aggressive tumor behavior through increased invasiveness and higher rates of lung metastases, but the biological mechanisms behind these features are not fully understood. In this study, we show that KRAS-mutant colorectal cancer upregulates integrin α6β4 through ERK/MEK signaling. Knocking-out integrin β4 (ITGB4) specifically depleted the expression of integrin α6β4 and this resulted in a reduction in the invasion and migration ability of the cancer cells. We also observed a reduction in the number and area of lung metastatic foci in mice that were injected with ITGB4 knockout KRAS-mutant colorectal cancer cells compared with the mice injected with ITGB4 wild-type KRAS-mutant colorectal cancer cells, while no difference was observed in liver metastases. Inhibiting integrin α6β4 in KRAS-mutant colorectal cancer could be a potential therapeutic target to diminish the KRAS-invasive phenotype and associated pulmonary metastasis rate.

IMPLICATIONS

Knocking-out ITGB4, which is overexpressed in KRAS-mutant colorectal cancer and promotes tumor aggressiveness, diminishes local invasiveness and rates of pulmonary metastasis.

ITGB4 Deficiency in Airway Epithelium Aggravates RSV Infection and Increases HDM Sensitivity

Background

The heterogeneity of RSV-infected pathology phenotype in early life is strongly associate with increased susceptibility of asthma in later life. However, the inner mechanism of this heterogeneity is still obscure. ITGB4 is a down-regulated adhesion molecular in the airway epithelia of asthma patients which may participate in the regulation of RSV infection related intracellular pathways.

Object

This study was designed to observe the involvement of ITGB4 in the process of RSV infection and the effect of ITGB4 deficiency on anti-RSV responses of airway epithelia.

Results

RSV infection caused a transient decrease of ITGB4 expression both in vitro and in vivo. Besides, ITGB4 deficiency induced not only exacerbated RSV infection, but also enhanced HDM sensitivity in later life. Moreover, IFN III (IFN-λ) was significantly suppressed during RSV infection in ITGB4 deficient airway epithelial cells. Furthermore, the suppression of IFN-λ were regulated by IRF-1 through the phosphorylation of EGFR in airway epithelial cells after RSV infection.

Conclusion

These results demonstrated the involvement of ITGB4 deficiency in the development of enhance RSV infection in early life and the increased HDM sensitivity in later life by down-regulation of IFN-λ through EGFR/IRF-1 pathway in airway epithelial cells.

Integrin α2 and β1 Cross-Communication with mTOR/AKT and the CDK-Cyclin Axis in Hepatocellular Carcinoma Cells

Simple Summary

Hepatocellular carcinoma (HCC) progression depends on two major processes, tumor growth and invasion. The present study investigated how these events are linked. A panel of HCC cell lines were stimulated with insulin-like growth factor-1 (IGF1) and the biological behavior was evaluated. IGF1 activated the proliferation and invasion cascade by altering the expression level of integrin α subtypes, which were associated with the AKT-mTOR pathway and the CDK-Cyclin axis. We assume that HCC progression is controlled by a fine-tuned network between IGF1 driven integrin signaling, the Akt-mTOR pathway, and the CDK-Cyclin axis. Concerted targeting of these pathways may, therefore, become an innovative option to prevent cancer dissemination.

Abstract

Integrin receptors contribute to hepatocellular carcinoma (HCC) invasion, while AKT-mTOR signaling controls mitosis. The present study was designed to explore the links between integrins and the AKT-mTOR pathway and the CDK-Cyclin axis. HCC cell lines (HepG2, Huh7, Hep3B) were stimulated with soluble collagen or Matrigel to activate integrins, or with insulin-like growth factor 1 (IGF1) to activate AKT-mTOR. HCC growth, proliferation, adhesion, and chemotaxis were evaluated. AKT/mTOR-related proteins, proteins of the CDK-Cyclin axis, focal adhesion kinase (FAK), and integrin-linked kinase (ILK) were determined following IGF1-stimulation or integrin knockdown. Stimulation with collagen or Matrigel increased tumor cell growth and proliferation. This was associated with significant alteration of the integrins α2, αV, and β1. Blockade of these integrins led to cell cycle arrest in G2/M and diminished the number of tumor cell clones. Knocking down the integrins α2 or β1 suppressed ILK, reduced FAK-phosphorylation and diminished AKT/mTOR, as well as the proteins of the CDK-Cyclin axis. Activating the cells with IGF1 enhanced the expression of the integrins α2, αV, β1, activated FAK, and increased tumor cell adhesion and chemotaxis. Blocking the AKT pathway canceled the enhancing effect of IGF on the integrins α2 and β1. These findings reveal that HCC growth, proliferation, and invasion are controlled by a fine-tuned network between α2/β1-FAK signaling, the AKT-mTOR pathway, and the CDK–Cyclin axis. Concerted blockade of the integrin α2/β1 complex along with AKT-mTOR signaling could, therefore, provide an option to prevent progressive dissemination of HCC.

EGFR/MET promotes hepatocellular carcinoma metastasis by stabilizing tumor cells and resisting to RTKs inhibitors in circulating tumor microemboli

The receptor tyrosine kinases (RTKs) family is well-recognized as vital targets for the treatment of hepatocarcinoma cancer (HCC) clinically, whereas the survival benefit of target therapy sorafenib is not satisfactory for liver cancer patients due to metastasis. EGFR and MET are two molecules of the RTK family that were related to the survival time of liver cancer patients and resistance to targeted therapy in clinical reports. However, the mechanism and clinical therapeutic value of EGFR/MET in HCC metastasis are still not completely clarified. The study confirmed that EGFR/MET was highly expressed in HCC cells and tissues and the phosphorylation was stable after metastasis. The expression of EGFR/MET was up-regulated in circulating tumor microemboli (CTM) to accelerate IL-8 production and resistance to the lethal effect of leukocytes. Meanwhile, highly expressed EGFR/MET effectively regulated the Ras/MAPK pathway and stabilized suspended HCC cells by facilitating proliferation and inhibiting apoptosis. Moreover, EGFR/MET promoted phosphorylation of hetero-RTKs, which was dependent on high-energy phosphoric acid compounds rather than their direct interactions. In conclusion, highly expressed EGFR/MET could be used in CTM identification and suitable for preventing metastasis of HCC in clinical practice.

SPC25 promotes hepatocellular carcinoma metastasis via activating the FAK/PI3K/AKT signaling pathway through ITGB4

Hepatocellular carcinoma (HCC) is a malignant tumor with a high metastatic rate. Recent studies have shown that the mitosis-associated spindle-assembly checkpoint regulatory protein spindle pole body component 25 homolog (SPC25) promotes HCC progression, although the underlying mechanism has yet to be fully elucidated. The aim of the present study was to investigate the mechanism through which SPC25 may promote HCC progression in greater detail. First, the expression of SPC25 was analyzed in publicly available databases to explore the association between SPC25 and HCC metastasis. Western blotting was subsequently performed to examine the level of SPC25 expression in different HCC cell lines. SPC25 was then silenced in HCCLM3 and Huh7 cells, and the effects of SPC25 silencing were investigated using cell proliferation, wound-healing, Transwell migration assays and an in vivo mouse model. Finally, the mechanism of SPC25 action with respect to the promotion of HCC metastasis was explored using microarray analysis and rescue experiments. The results obtained demonstrated that SPC25 is highly expressed in HCC, and this high level of expression is associated with poor prognosis and metastasis. Moreover, SPC25 silencing led to a marked inhibition of the invasion and migration of HCC cells both in vitro and in vivo. The gene-expression profiling and mechanistic experiments suggest that SPC25 preferentially influences the expression of genes associated with extracellular matrix (ECM)-integrin interactions, including integrin subunit β4 (ITGB4), an upstream element of the integrin pathway. ITGB4 upregulation partly reversed the decline in cell invasion and migration capacities that resulted from SPC25 silencing. Furthermore, deleting both SPC25 and ITGB4 caused a decrease in the phosphorylation of focal adhesion kinase (FAK), phosphoinositide 3-kinase (PI3K) and AKT, which are downstream elements of the integrin pathway. Taken together, the results of the present study demonstrated the important role of SPC25 as a prognostic indicator and as a promoter of metastasis in HCC, and the underlying mechanism of its action has been partially elucidated, suggesting that SPC25 could be used as a biomarker and as a target for therapeutic intervention in the treatment of HCC.

ITGB4 deficiency induces mucus hypersecretion by upregulating MUC5AC in RSV-infected airway epithelial cells

Respiratory syncytial virus (RSV) infection is the main cause of bronchiolitis in children. Excessive mucus secretion is one of the primary symbols in RSV related lower respiratory tract infections (RSV-related LRTI), which is closely associated with the occurrence and development of asthma in later life. Integrin β4 (ITGB4) is down-regulated in the airway epithelial cells (AECs) of asthma patients which plays a critical role in the pathogenesis of asthma. However, whether ITGB4 is involved in the pathological processes of RSV infection remains unclear. In this study, we found that decreased expression of ITGB4 was negatively correlated with the level of MUC5AC in childhood AECs following RSV infection. Moreover, ITGB4 deficiency led to mucus hypersecretion and MUC5AC overexpression in the small airway of RSV-infected mice. MUC5AC expression was upregulated by ITGB4 in HBE cells through EGFR, ERK and c-Jun pathways. EGFR inhibitors treatment inhibited mucus hypersecretion and MUC5AC overexpression in ITGB4-deficient mice after RSV infection. Together, these results demonstrated that epithelial ITGB4 deficiency induces mucus hypersecretion by upregulating the expression of MUC5AC through EGFR/ERK/c-Jun pathway, which further associated with RSV-related LRTI.

Silencing ZIC2 abrogates tumorigenesis and anoikis resistance of non-small cell lung cancer cells by inhibiting Src/FAK signaling

Aberrant expression of the zinc finger protein (ZIC) family has been extensively reported to contribute to progression and metastasis in multiple human cancers. However, the functional roles and underlying mechanisms of ZIC2 in non-small cell lung cancer (NSCLC) are largely unknown. In this study, ZIC2 expression was evaluated using qRT-PCR, western blot, and immunohistochemistry, respectively. Animal experiments in vivo and functional assays in vitro were performed to investigate the role of ZIC2 in NSCLC. Luciferase assays and chromatin immunoprecipitation (ChIP) were carried out to explore the underlying target involved in the roles of ZIC2 in NSCLC. Here, we reported that ZIC2 was upregulated in NSCLC tissues, and high expression of ZIC2 predicted worse overall and progression-free survival of NSCLC patients. Silencing ZIC2 repressed tumorigenesis and reduced the anoikis resistance of NSCLC cells. Mechanical investigation further revealed that silencing ZIC2 transcriptionally inhibited Src expression and inactivated steroid receptor coactivator/focal adhesion kinase signaling, which further attenuated the anoikis resistance of NSCLC cells. Importantly, our results showed that the number of circulating tumor cells (CTCs) was positively correlated with ZIC2 expression in NSCLC patients. Collectively, our findings unravel a novel mechanism implicating ZIC2 in NSCLC, which will facilitate the development of anti-tumor strategies in NSCLC.

Synthetic Evaluation of MicroRNA-1-3p Expression in Head and Neck Squamous Cell Carcinoma Based on Microarray Chips and MicroRNA Sequencing

Background

MicroRNA-1-3p (miR-1-3p) exerts significant regulation in various tumor cells, but its molecular mechanisms in head and neck squamous cell carcinoma (HNSCC) are still ill defined. This study is aimed at detecting the expression of miR-1-3p in HNSCC and at determining its significant regulatory pathways.

Methods

Data were obtained from the Cancer Genome Atlas (TCGA), Gene Expression Omnibus (GEO), Oncomine, ArrayExpress, Sequence Read Archive (SRA) databases, and additional literature. Expression values of miR-1-3p in HNSCC were analyzed comprehensively. The R language software was employed to screen differentially expressed genes, and bioinformatics assessment was performed. One sequence dataset (HNSCC: n = 484; noncancer: n = 44) and 18 chip datasets (HNSCC: n = 656; noncancer: n = 199) were obtained.

Results

The expression of miR-1-3p in HNSCC was visibly decreased in compare with noncancerous tissues. There were distinct differences in tumor state (P = 0.0417), pathological stage (P = 0.0058), and T stage (P = 0.0044). Comprehensive analysis of sequence and chip data also indicated that miR-1-3p was lowly expressed in HNSCC. The diagnostic performance of miR-1-3p in HNSCC is reflected in the sensitivity and specificity of the collection, etc. Bioinformatics analysis showed the possible biological process, cellular component, molecular function, and KEGG pathways of miR-1-3p in HNSCC. And ITGB4 was a possible target of miR-1-3p.

Conclusions

miR-1-3p's low expression may facilitate tumorigenesis and evolution in HNSCC through signaling pathways. ITGB4 may be a key gene in targeting pathways but still needs verification through in vitro experiments.

Identification of prognostic and bone metastatic alternative splicing signatures in bladder cancer

Bladder cancer (BLCA), originating from the epithelium of the urinary bladder, was the second most common malignancy in the urinary system with a high metastasis rate and poor post-metastasis prognosis. Alternative splicing events (ASEs) were regarded as important markers of tumor progression and prognosis, however, their roles in bladder cancer bone metastasis have not been recognized. In this study, we constructed a predictive model based on ASEs and explored the molecular mechanism of ASEs in BLCA bone metastasis, based on data from the Cancer Genome Atlas (TCGA) and TCGASpliceSeq databases. We proposed the hypothesis that the splicing events of ITGB4 was regulated by the splicing factor JUP, and this regulation might play a key role in BLCA bone metastasis through the glycosphingolipid biosynthesis ganglio series pathway.

Integrin β4 as a Potential Diagnostic and Therapeutic Tumor Marker

Integrin β4 (ITGβ4) is a class of transmembrane adhesion molecules composed of hemidesmosomes (HDs). Its unique long intracellular domain provides intricate signal transduction functions. These signal transduction effects are especially prominent in tumors. Many recent studies have shown that integrin β4 is differentially expressed in various tumors, and it plays a vital role in tumor invasion, proliferation, epithelial–mesenchymal transition, and angiogenesis. Therefore, we categorize the research related to integrin β4, starting from its structure and function in tumor tissues, and provide a basic description. Based on its structure and function, we believe that integrin β4 can be used as a tumor marker. In clinical practice, it is described as a diagnostic marker for the targeted treatment of cancer and will be helpful in the clinical diagnosis and treatment of tumors.

Stanniocalcin-2 promotes cell EMT and glycolysis via activating ITGB2/FAK/SOX6 signaling pathway in nasopharyngeal carcinoma

Stanniocalcin-2 (STC2) has been proved to regulate a variety of signaling pathways including cell growth, metastasis, and therapeutic resistance. However, the role of STC2 in the regulation of nasopharyngeal carcinoma (NPC) remains poorly understood. In this study, we investigated the regulatory function of STC2 on epithelial-mesenchymal transition (EMT) and glycolysis traits in NPC and revealed the underlying molecular mechanisms. We found that STC2 was highly expressed in primary nasopharyngeal carcinoma tissues and lymph node metastatic tissues. Silencing of STC2 inhibited cell proliferation, invasion, and glycolysis. Further analyses for the clinical samples demonstrated that STC2 expression was associated with the poor clinical progression. Moreover, we demonstrated the interaction of ITGB2 with STC2 and its involvement in STC2-mediated ITGB2/FAK/SOX6 axis. Collectively, our results provide new insights into understanding the regulatory mechanism of STC2 and suggest that the STC2/ITGB2/FAK/SOX6 signaling axis may be a potential therapeutic target for NPC.

Long Noncoding RNAs in Gastrointestinal Cancer: Tumor Suppression Versus Tumor Promotion

Approximately 80% of the human genome harbors biochemical marks of active transcription that its majority transcribes to noncoding RNAs, namely long noncoding RNAs (lncRNAs). LncRNAs are heterogeneous RNA transcripts that regulate critical biological processes such as cell survival and death. They involve in the progression of different cancers by affecting transcriptional and post-transcriptional modifications as well as epigenetic control of numerous tumor suppressors and oncogenes. Recent findings show that aberrant expression of lncRNAs is associated with tumor initiation, progression, invasion, and overall survival of patients with gastrointestinal (GI) cancers. Some lncRNAs play as tumor suppressors in all GI cancers, but others play as tumor promoters. However, some other lncRNAs might function as a tumor suppressor in one GI cancer, but as a tumor promoter in another GI cancer type. This fact highlights possible context dependency of the expression patterns and roles of at least some lncRNAs in GI cancer development and progression. Here, we review the functional relation of lncRNAs involved in the development and progression of GI cancer by focusing on their roles as tumor suppressor and tumor promoter genes.

Airway epithelial integrin β4 suppresses allergic inflammation by decreasing CCL17 production

Airway epithelial cells (AECs) play a key role in asthma susceptibility and severity. Integrin β4 (ITGB4) is a structural adhesion molecule that is down-regulated in the airway epithelium of asthma patients. Although a few studies hint toward the role of ITGB4 in asthmatic inflammation pathogenesis, their specific resultant effects remain unexplored. In the present study, we determined the role of ITGB4 of AECs in the regulation of Th2 response and identified the underpinning molecular mechanisms. We found that ITGB4 deficiency led to exaggerated lung inflammation and AHR with higher production of CCL17 in house dust mite (HDM)-treated mice. ITGB4 regulated CCL17 production in AECs through EGFR, ERK and NF-κB pathways. EFGR-antagonist treatment or the neutralization of CCL17 both inhibited exaggerated pathological marks in HDM-challenged ITGB4-deficient mice. Together, these results demonstrated the involvement of ITGB4 deficiency in the development of Th2 responses of allergic asthma by down-regulation of EGFR and CCL17 pathway in AECs.

Inhibition of p70 isoforms of S6K1 induces anoikis to prevent transformed human hepatocyte growth

AIMS

The mTOR/S6K1 signaling axis, known for cell growth regulation, is hyper-activated in multiple cancers. In this study, we have examined the mechanisms for ribosomal protein p70-S6 kinase 1 (S6K1) associated transformed human hepatocyte (THH) growth regulation.

MAIN METHODS

THH were treated with p70-S6K1 inhibitor and analyzed for cell viability, cell cycle distribution, specific marker protein expression by western blot, and tumor inhibition in a xenograft mouse model. We validated our results by knockdown of p70-S6K1 using specific siRNA.

KEY FINDINGS

p70-S6K1 inhibitor treatment caused impairment of in vitro hepatocyte growth, and arrested cell cycle progression at the G1 phase. Further, p70-S6K1 inhibitor treatment exhibited a decrease in FAK and Erk activation, followed by altered integrin-β1 expression, caspase 8, and PARP cleavage appeared to be anoikis like growth inhibition. p70-S6K1 inhibitor also depolymerized actin microfilaments and diminished active Rac1/Cdc42 complex formation for loss of cellular attachment. Similar results were obtained with other transformed human hepatocyte cell lines. p70-S6K1 inhibition also resulted in a reduced phospho-EGFR, Slug and Twist; implicating an inhibition of epithelial-mesenchymal transition (EMT) state. A xenograft tumor model, generated from implanted THH in nude mice, following intraperitoneal injection of S6K1 inhibitor prevented further tumor growth.

SIGNIFICANCE

Our results suggested that p70-S6K1 inhibition alters orchestration of cell cycle progression, induces cell detachment, and sensitizes hepatocyte growth impairment. Targeting p70 isoform of S6K1 by inhibitor may prove to be a promising approach together with other therapies for hepatocellular carcinoma (HCC) treatment.

circRASGRF2 functions as an oncogenic gene in hepatocellular carcinoma by acting as a miR-1224 sponge

Circular RNAs (circRNAs) are a class of non-coding RNAs broadly expressed in cells of various species. However, the contributions and molecular mechanisms of circRNAs to hepatocellular carcinoma (HCC) remain largely unknown. In the present study, we compared the expression of circRNAs between five paired HCC and adjacent noncancerous liver (ANL) tissues by using RNA-sequencing (RNA-seq). circRASGRF2 (a circRNA located on chromosome 5 and derived from RASGRF2, hsa_circ_0073181) was identified and validated by quantitative reverse transcriptase PCR. The role of circRASGRF2 in HCC progression was assessed both in vitro and in vivo. Mechanistically, RNA immunoprecipitation and luciferase reporter assays were performed to confirm the interaction between circRASGRF2 and miR-1224 in HCC. circRASGRF2 was found to be significantly upregulated in HCC tissues and HCC cell lines compared with paired ANL tissues and normal cells. Our in vivo and in vitro data indicated that knockdown of circRASGRF2 inhibits the proliferation and migration of HCC cells. Mechanistically, we found that circRASGRF2 could promote the expression of focal adhesion kinase (FAK) by sponging miR-1224. Our data showed that circRASGRF2 is a central component linking circRNAs to progression of HCC, making it a potential therapeutic target.

AHNAK2 Is Associated with Poor Prognosis and Cell Migration in Lung Adenocarcinoma

BACKGROUND

Lung adenocarcinoma (LUAD), as the main subtype of lung cancer, is one of the common causes of cancer-related deaths worldwide. The AHNAK family is correlated with cell structure and migration, cardiac calcium channel signaling, and tumor metastasis. Previous studies showed AHNAK2 could promote tumor progression and cell migration in melanoma and renal clear cell carcinoma. However, the role of AHNAK2 in LUAD remains unknown.

METHODS

We examined the levels of AHNAK2 in pathological specimens and the database of Clinical Proteomic Tumor Analysis Consortium-Lung adenocarcinoma (CPTAC-LUAD), The Cancer Genome Atlas-Lung Adenocarcinoma (TCGA-LUAD), Gene Expression Omnibus dataset (GSE72094, GSE26939), and The Genotype-Tissue Expression (GTEx) of lung tissue samples. Univariate Cox regression, multivariate Cox regression, and Kaplan-Meier survival analysis were performed to reveal the relationship between AHNAK2 and prognosis. A nomogram was constructed to predict 2- or 3-year overall survival and validated via calibration curves, receiver operating characteristic (ROC) analysis, and decision curve analysis (DCA). Furthermore, Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were used to explore the functional role of AHNAK2 in lung adenocarcinoma. Finally, by transfecting siRNA, we examined the regulatory effect of AHNAK2 on cell migration.

RESULTS

The expression of AHNAK2 was upregulated in tumor samples and correlated with poor prognosis in LUAD patients. Nomogram with AHNAK2 and clinical parameters showed a good prediction in overall survival (OS), especially the 2-year OS. In addition, functional analyses and wound healing assay suggested that AHNAK2 might be involved in the regulation of migration in LUAD.

CONCLUSION

In summary, our study showed that AHNAK2 might be a novel biomarker in LUAD and revealed the potential mechanism of AHNAK2 in LUAD progression which could provide new insights for target therapy.

ZKSCAN3 drives tumor metastasis via integrin β4/FAK/AKT mediated epithelial-mesenchymal transition in hepatocellular carcinoma

Background

ZKSCAN3, a zinc-finger transcription factor containing KRAB and SCAN domains, has been reported to be regulated in several human cancers. However, its expression and function in hepatocellular carcinoma (HCC) remains unknown.

Methods

Expression of ZKSCAN3 in HCC was analyzed by western blotting, immunohistochemistry, and real time PCR. Its correlation with the clinicopathological characteristics and prognosis of HCC patients was analyzed. The effects of ZKSCAN3 on the migration and invasion were determined by Transwell assays. The potential downstream targets of ZKSCAN3 and related molecular mechanisms were clarified by Western blot and dual luciferase reporter assay.

Results

In this study, we demonstrated for the first time that ZKSCAN3 mRNA and protein was up-regulated in HCC tissues and cell lines. High ZKSCAN3 expression was significantly associated with poor prognostic features, including advanced TNM stage and vascular invasion. For 5-year survival, ZKSCAN3 served as a potential prognostic marker of HCC patients. Functionally, ZKSCAN3 promoted migration, invasion and EMT progress via directly binding to integrin β4 (ITGB4) promoter and enhanced its expression. Further investigation proved that ITGB4 triggers the focal adhesion kinase (FAK) to activate the AKT signaling pathway. Inactivation of FAK and AKT by their specific inhibitors respectively reversed the effects of ZKSCAN3 on HCC cells. In addition, we demonstrated that ZKSCAN3 expression was regulated by miR-124. In HCC tissues. MiR-124 has an inverse correlation with ZKSCAN3 expression.

Conclusion

We demonstrate for the first time that ZKSCAN3 is overexpressed in HCC tissues and promotes migration, invasion and EMT process through ITGB4-dependent FAK/AKT activation, which was regulated by miR-124, suggesting the potential therapeutic value for HCC.

Whole-exome mutational landscape of metastasis in patient-derived hepatocellular carcinoma cells

In order to explore the genomic basis for liver cancer metastasis, whole-exome sequencing (WES) was performed on patient-derived hepatocellular carcinoma (HCC) cell lines with differential metastatic potentials and analyzed their clonal evolution relationships. An evolutionary tree based on genomic single nucleotide polymorphism (SNP) was constructed in MegaX software. The WES data showed that the average percentage of heterogeneous mutations in each HCC cell lines was 16.55% (range, 15.38%–18.17%). C: G > T: A and T: A > C: G somatic transitions were the two most frequent substitutions. In these metastatic HCC cell lines, non-silent gene mutations were found in 21.88% of known driver genes and 10 classical signaling pathways. The protein interaction network was constructed by STRING, and hub genes were found in the shared trunk mutation genes and the heterogeneous branch mutations respectively. In cBioPortal database, some of the selected hub genes were found to be associated with poor overall survival (OS) of HCC patients. Among the mutated HCC driver genes, a novel KEAP1 mutation with a homozygous frameshift truncation at the c-terminal Nrf2 binding region was detected and verified in MHCC97-H and HCC97LM3 cells. In conclusion, WES data demonstrate that HCC cell lines from tumor biopsy specimens of the same patient have obtained different metastatic potentials through repeated selection in rodents in vivo, and they do indeed have a genetic relationship at the genomic level.

Airway epithelial ITGB4 deficiency in early life mediates pulmonary spontaneous inflammation and enhanced allergic immune response

Lung immune responses to respiratory pathogens and allergens are initiated in early life which will further influence the later onset of asthma. The airway epithelia form the first mechanical physical barrier to allergic stimuli and environmental pollutants, which is also the key regulator in the initiation and development of lung immune response. However, the epithelial regulation mechanisms of early-life lung immune responses are far from clear. Our previous study found that integrin β4 (ITGB4) is decreased in the airway epithelium of asthma patients with specific variant site. ITGB4 deficiency in adult mice aggravated the lung Th2 immune responses and enhanced airway hyper-responsiveness (AHR) with a house dust mite (HDM)-induced asthma model. However, the contribution of ITGB4 to the postnatal lung immune response is still obscure. Here, we further demonstrated that ITGB4 deficiency following birth mediates spontaneous lung inflammation with ILC2 activation and increased infiltration of eosinophils and lymphocytes. Moreover, ITGB4 deficiency regulated thymic stromal lymphopoietin (TSLP) production in airway epithelial cells through EGFR pathways. Neutralization of TSLP inhibited the spontaneous inflammation significantly in ITGB4-deficient mice. Furthermore, we also found that ITGB4 deficiency led to exaggerated lung allergic inflammation response to HDM stress. In all, these findings indicate that ITGB4 deficiency in early life causes spontaneous lung inflammation and induces exaggerated lung inflammation response to HDM aeroallergen.

Integrin β4-Targeted Cancer Immunotherapies Inhibit Tumor Growth and Decrease Metastasis

Integrin β4 (ITGB4) has been shown to play an important role in the regulation of cancer stem cells (CSC). Immune targeting of ITGB4 represents a novel approach to target this cell population, with potential clinical benefit. We developed two immunologic strategies to target ITGB4: ITGB4 protein-pulsed dendritic cells (ITGB4-DC) for vaccination and adoptive transfer of anti-CD3/anti-ITGB4 bispecific antibody (ITGB4 BiAb)-armed tumor-draining lymph node T cells. Two immunocompetent mouse models were utilized to assess the efficacy of these immunotherapies in targeting both CSCs and bulk tumor populations: 4T1 mammary tumors and SCC7 head and neck squamous carcinoma cell line. Immunologic targeting of ITGB4 utilizing either ITGB4-DC or ITGB4 BiAb-T cells significantly inhibited local tumor growth and metastases in both the 4T1 and SCC7 tumor models. Furthermore, the efficacy of both of these ITGB4-targeted immunotherapies was significantly enhanced by the addition of anti-PD-L1. Both ITGB4-targeted immunotherapies induced endogenous T-cell cytotoxicity directed at CSCs as well as non-CSCs, which expressed ITGB4, and immune plasma-mediated killing of CSCs. As a result, ITGB4-targeted immunotherapy reduced not only the number of ITGB4^high CSCs in residual 4T1 and SCC7 tumors but also their tumor-initiating capacity in secondary mouse implants. In addition, treated mice demonstrated no apparent toxicity. The specificity of these treatments was demonstrated by the lack of effects observed using ITGB4 knockout 4T1 or ITGB4-negative CT26 colon carcinoma cells. Because ITGB4 is expressed by CSCs across a variety of tumor types, these results support immunologic targeting of ITGB4 as a promising therapeutic strategy.Significance: This study identifies a novel mechanism of resistance to anti-PD-1/PD-L1 immunotherapy mediated by HPV E5, which can be exploited using the HPV E5 inhibitor rimantadine to improve outcomes for head and neck cancer patients.

The clinical significance and potential molecular mechanism of integrin subunit beta 4 in laryngeal squamous cell carcinoma

The relationship between integrin beta 4 (ITGB4) expression and laryngeal squamous cell carcinoma (LSCC) remains unclarified. The object of the present study was to explore the clinical significance and potential molecular mechanism of ITGB4 in LSCC. The protein level of ITGB4 was significantly higher in 46 LSCC patients than in 26 non-LSCC tissues detected by in-house immunohistochemistry. Consistently, ITGB4 mRNA level was also greatly upregulated based on microarray and RNA-seq data (standard mean difference, SMD = 1.62, 95 % CI: 1.23-2.00). And the area under curves (AUC) of summary receiver operator characteristic (SROC) was 0.87 (95 % CI: 0.84-0.90) based on 172 cases of LSCC and 59 cases of non-cancerous controls. Ninety genes were intersected by the ITGB4 related genes and LSCC differential expressed genes (DEGs) from all available microarray and RNA-seq datasets. Based on Gene Ontology (GO) analysis, the top terms of biological process (BP), cellular component (CC) and molecular function (MF) for the 90 ITGB4 related DEGs were extracellular matrix organization, basement membrane and extracellular matrix structural constituent, respectively. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that ITGB4 related DEGs mainly participated in the pathways of ECM-receptor interaction, Focal adhesion and Small cell lung cancer. Moreover, the Protein-Protein Interaction (PPI) network indicated that ITGA3, ITGA5, ITGB4, MET, LAMA3, and COL4A1 might be the core genes of LSCC development related to ITGB4. In conclusion, high ITGB4 expression may lead to the occurrence and development of LSCC via various signaling pathways.

Rosmarinic acid inhibits proliferation and invasion of hepatocellular carcinoma cells SMMC 7721 via PI3K/AKT/mTOR signal pathway

OBJECTIVE

To investigate the effect of rosmarinic acid (RosA) on hepatocellular carcinoma cell in vivo and in vitro and to explore its possible mechanism of anti-hepatocarcinoma.

METHODS

The hepatocellular carcinoma cell line SMMC-7721 was treated with different concentrations of RosA (0, 20, 50, 100 μmol/L) to detect cell proliferation, cell cycle, apoptosis and invasion.PI3K pathway-specific activator IGF-1 was used to explore whether the mechanism for RosA action relates to PI3K/AKT signal pathway.Nude mice inoculated with SMMC-7721 cells were treated with different doses of RosA (0, 5, 10 and 20 mg/kg) to detect the tumor formation of cancer cells in vivo.

RESULTS

RosA significantly inhibited the proliferation of SMMC-7721 cells and induced G1 arrest and apoptosis in a dose-dependent manner. RosA might inhibit cell invasion by regulating epithelial-mesenchymal transition. Rescue experiments showed that IGF-1 could reverse the inhibition of PI3K/AKT/mTOR signal pathway by RosA and the effect on proliferation, apoptosis, cell cycle, invasion and EMT by IGF-1 in SMMC-7721 cells;RosA could inhibit tumor formation of SMMC-7721 cells in vivo.

CONCLUSION

RosA can inhibit the proliferation and invasion of hepatocellular carcinoma cell in vitro and inhibit tumour growth in vivo and the mechanism may relate to inhibiting the activation of PI3K/AKT signal pathway.

Integrin β4 promotes invasion and anoikis resistance of papillary thyroid carcinoma and is consistently overexpressed in lymphovascular tumor thrombus

Although the majority of papillary thyroid cancers (PTC) are indolent, a subset of PTCs behaves aggressively due to extensive invasion and distant metastasis. Integrin β4, a member of the integrin family, has been shown to enhance the progression in some malignancies; however, its role in PTC remains unclear. Here, we demonstrated that β4 overexpression was associated with extrathyroid extension, lymph node metastasis, high TNM stage, and poor overall survival based on The Cancer Genome Atlas cohort. Immunohistochemistry showed that β4 expression was significantly upregulated in the tumors with infiltrating growth pattern, as well as those with positive lymphovascular invasion. Moreover, β4 was invariably overexpressed in the lymphovascular tumor thrombi, which has not been reported before. After shRNA-induced knockdown of β4 in vitro, the migration, invasion and scratch repair ability of the tumor cells were significantly reduced. Furthermore, β4 reduction decreased anchorage-independent growth and increased anoikis. The bioinformatics analysis revealed that approximately 70 pathways were significantly dysregulated in the high β4 expression group. The MAPK pathway and propanoate metabolism were located in the network center of those pathways. Taken together, our results suggest that β4 could promote the tumor's aggressiveness by enhancing invasion and antagonizing anoikis. The upregulated expression of β4 in the tumor thrombi is intrinsically linked to its role in strengthening the anoikis resistance.

Circ_0015756 promotes proliferation, invasion and migration by microRNA-7-dependent inhibition of FAK in hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) afflicts more than half a million people each year worldwide. It was reported that circ_0015756 was up-regulated in HCC, but the mechanism did not extensively studied. Methods: we collected 24 paired cancerous and noncancerous liver tissues surgically resected from HCC patients. HCC cell proliferation, invasion, migration and apoptosis in vitro were evaluated using MTT assay, Transwell assay, scratch test and Annexin-V/PI staining respectively. Interactions between circ_0015756 and miR-7, miR-7 and FAK were further validated by the luciferase reporter assay. Tumor xenografts of HCC cells with circ_0015756 knockdown were established in nude mice. Results: The expression level of circ_0015756 was increased and the expression level of miR-7 was diminished in cancerous liver tissues relative to noncancerous liver tissues. Circ_0015756 knockdown was shown to increase the expression of miR-7, reduce the proliferation, invasion, migration and resistance to apoptosis, and down-regulate the expression of FAK in HCC. We found miR-7 impaired expression of FAK to inhibit HCC cells, suggesting that miR-7 is responsible for the dysfunction of FAK. Importantly, we showed circ_0015756 could up-regulate FAK via targeting miR-7. These in vitro findings were reproduced in vivo that circ_0015756 knockdown decreased HCC xenograft growth. Conclusion: Our present study reveals a model of HCC development that is composed of circ_0015756, miR-7 and FAK. Modulation of their levels exhibits a promise in the treatment of HCC. Abbreviations: HCC: hepatocellular carcinoma; circRNAs: circular RNAs; miRNA/miR: microRNA; miR-7: microRNA-7; FAK: focal adhesion kinase; KLF-4: kruppel like factor 4; DKK1: dickkopf WNT signaling pathway inhibitor 1; ccRCC: clear cell renal cell carcinoma; PI3K: phosphoinositide 3-kinase; Ct: comparative threshold cycle; RPMI: Roswell Park Memorial Institute; FBS: fetal bovine serum; RT: reverse transcription; qPCR: quantitative polymerase chain reaction; RIPA: radioimmunoprecipitation assay; SDS-PAGE: sodium dodecyl sulfate-polyacrylamide gel electrophoresis; PVDF: polyvinylidene difluoride; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; MTT: 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; DMSO: dimethyl sulfoxide; DMEM: Dulbecco's modified Eagle's medium; PI: propidium iodide; SPF: specific pathogen-free; SD: standard deviation; p-Akt: phosphorylated-Akt; shRNAs: small hairpin RNAs; 3'UTR: 3'-untranslated regions.

MROH7-TTC4 read-through lncRNA suppresses vascular endothelial cell apoptosis and is upregulated by inhibition of ANXA7 GTPase activity

Apoptosis of vascular endothelial cells (VEC) is the main form of vascular injury that is closely linked to numerous cardiovascular diseases. Therefore, it is important to find new factors that can suppress VEC apoptosis. By using long noncoding RNA (lncRNA) microarray analysis, we found a new read-through lncRNA, MROH7-TTC4, which acted as an apoptosis inhibitor in VECs. Furthermore, by using the inhibitor (ABO) of annexin A7 (ANXA7) GTPase, we discovered that ANXA7 translocated into nucleus and interacted with 5'→3' exoribonuclease (XRN2). The decreased XRN2 phosphorylation induced by ANXA7 GTPase activity inhibition, promoted MROH7-TTC4 expression. Moreover, T-cell intracellular antigen-1 (TIA1), a binding protein of MROH7-TTC4, processed it into MROH7 and TTC4 that could inhibit VEC apoptosis. Here, we conclude that inhibiting ANXA7 GTPase activity promotes the interaction of ANXA7 and XRN2 in nucleus, which regulates the read-through transcription of MROH7-TTC4, and TIA1 is responsible for the process of MROH7-TTC4 that inhibits apoptosis through MROH7 and TTC4.

DEPTOR induces a partial epithelial-to-mesenchymal transition and metastasis via autocrine TGFβ1 signaling and is associated with poor prognosis in hepatocellular carcinoma

Background

DEPTOR is an endogenous inhibitor of mTORC1 and mTORC2 that plays a vital role in the progression of human malignances. However, the biological function of DEPTOR in HCC metastasis and the underlying molecular mechanisms are still unclear.

Methods

Western blot analysis and immunohistochemistry(IHC) were employed to examine DEPTOR expression in HCC cell lines and tissues. A series of in vivo and in vitro assays were performed to determine the function of DEPTOR and the possible mechanisms underlying its role in HCC metastasis.

Results

We found that DEPTOR was frequently overexpressed in HCC tissues, and its high expression was associated with high serum AFP levels, increased tumor size, vascular invasion and more advanced TMN and BCLC stage, as well as an overall poor prognosis. Functional experiments demonstrated that DEPTOR silencing inhibited the proliferation and mobility of HCC cells in vitro and suppressed tumor growth and metastasis of HCC cells in vivo. Accordingly, DEPTOR overexpression promoted the invasion and metastasis of HCC cells in vitro and in vivo, but had no effect on cell proliferation in vitro. Overexpression of DEPTOR induced EMT by snail induction. Conversely, knockdown of snail expression impaired the DEPTOR-induced migration, invasion and EMT of HCC cells. Furthermore, we found that the increase of snail expression by DEPTOR overexpression was due to an activation of TGF-β1-smad3/smad4 signaling possibly through feedback inhibition of mTOR.

Conclusion

DEPTOR promotes the EMT and metastasis of HCC cells by activating the TGF-β1-smad3/smad4-snail pathway via mTOR inhibition. Therefore, targeting DEPTOR may be an ideal treatment strategy for inhibiting the growth and metastasis of HCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1220-1) contains supplementary material, which is available to authorized users.

Mechanisms behind Temsirolimus Resistance Causing Reactivated Growth and Invasive Behavior of Bladder Cancer Cells In Vitro

Background: Although mechanistic target of rapamycin (mTOR) inhibitors, such as temsirolimus, show promise in treating bladder cancer, acquired resistance often hampers efficacy. This study evaluates mechanisms leading to resistance. Methods: Cell growth, proliferation, cell cycle phases, and cell cycle regulating proteins were compared in temsirolimus resistant (res) and sensitive (parental—par) RT112 and UMUC3 bladder cancer cells. To evaluate invasive behavior, adhesion to vascular endothelium or to immobilized extracellular matrix proteins and chemotactic activity were examined. Integrin α and β subtypes were analyzed and blocking was done to evaluate physiologic integrin relevance. Results: Growth of RT112res could no longer be restrained by temsirolimus and was even enhanced in UMUC3res, accompanied by accumulation in the S- and G2/M-phase. Proteins of the cdk-cyclin and Akt-mTOR axis increased, whereas p19, p27, p53, and p73 decreased in resistant cells treated with low-dosed temsirolimus. Chemotactic activity of RT112res/UMUC3res was elevated following temsirolimus re-exposure, along with significant integrin α2, α3, and β1 alterations. Blocking revealed a functional switch of the integrins, driving the resistant cells from being adhesive to being highly motile. Conclusion: Temsirolimus resistance is associated with reactivation of bladder cancer growth and invasive behavior. The α2, α3, and β1 integrins could be attractive treatment targets to hinder temsirolimus resistance.