Epidermal Growth Factor Receptor Family and its Role in Gastric Cancer

G protein pathway suppressor 2 suppresses gastric cancer by destabilizing epidermal growth factor receptor

G protein pathway suppressor 2 (GPS2) is expressed in most human tissues, including the stomach. However, the biological functions of GPS2 in cancer, as well as the underlying molecular mechanisms, remain poorly understood. Here, we report that GPS2 expression was aberrantly downregulated in gastric cancer (GC) tissues compared with control tissues. Clinicopathologic analysis showed that low GPS2 expression was significantly correlated with pathological grade, lymph node stage, and invasive depth. Kaplan‐Meier analysis indicated that patients with low GPS2 expression showed poorer overall survival rates than those with high GPS2 expression. Moreover, GPS2 overexpression decreased GC cell proliferation, colony formation, tumorigenesis, and invasion. Overexpression of GPS2 reduced the protein expression of epidermal growth factor receptor (EGFR) and inhibited its downstream signaling in GC cells. Interestingly, GPS2 decreased EGFR protein expression, which was reversed by a lysosome inhibitor. Furthermore, GPS2 reduced EGFR protein stability by enhancing the binding of EGFR and an E3 ligase, c‐Cbl, which promoted the ubiquitination of EGFR, ultimately leading to its degradation through the lysosomal pathway. Further analysis indicated that GPS2 activated autophagy and promoted the autophagic flux by destabilizing EGFR. Taken together, these results suggest that low GPS2 expression is associated with GC progression and provide insights into the applicability of the GPS2‐EGFR axis as a potential therapeutic target in GC.

The Radiolabeled HER3 Targeting Molecules for Tumor Imaging

The human epidermal growth factor receptor (HER) family plays pivotal roles in physiologic and pathologic conditions (such as tumor growth, proliferation, and progression in multiple epithelial malignancies). All the family members are considered tyrosine kinase, while HER3 as a member of this family shows no intrinsic tyrosine kinase. HER3 is called ‘pseudokinase’ because it undergoes heterodimerization and forms dimers such as HER2-HER3 and HER1 (EGFR)-HER3. The exact role of HER3 in cancer is still unclear; however, the overexpression of this receptor is involved in the poor prognosis of malignancies. To that end, different studies investigated the development of radiotracers for imaging of HER3. The main focus of this review is to gather all the studies on developing new radiotracers for imaging of HER3.

WBP2 promotes gastric cancer cell migration via novel targeting of LATS2 kinase in the Hippo tumor suppressor pathway

Dysregulation of signaling pathways is responsible for many human diseases. The lack of understanding of the molecular etiology of gastric cancer (GC) poses a substantial challenge to the development of effective cancer therapy. To better understand the molecular mechanisms underlying the pathogenesis of GC, which will facilitate the identification and development of effective therapeutic approaches to improve patient outcomes, mass spectrometry-based phosphoproteomics analysis was performed to map the global molecular changes in GC. A total of 530 proteins with altered phosphorylation levels were detected across a panel of 15 normal and GC cell lines. WW domain-binding protein 2 (WBP2) was validated to be upregulated in a subset of GC cell lines. WBP2 is overexpressed in 61% cases of GC compared to non-cancer tissues and high WBP2 expression correlates with poor clinical outcomes. WBP2 was found to be required for GC cell migration but is dispensable for cell growth and proliferation. WBP2 knockdown increased p-LATS2 with a concomitant increase in p-YAP, resulting in the cytoplasmic retention of YAP and ultimately the inhibition of YAP/TEAD activity and downregulation of TEAD target genes--CTGF and CYR61. Importantly, the loss of LATS2 reversed the activation of Hippo pathway caused by WBP2 knockdown, indicating that WBP2 acts through LATS2 to exert its function on the Hippo pathway. Moreover, WBP2 interacted with LATS2 to inhibit its phosphorylation and activity. In conclusion, our study established a pivotal role for WBP2 in the promotion of GC cell migration via a novel mechanism that inactivates the Hippo pathway transducer LATS2.

Molecular Pathways and Druggable Targets in Head and Neck Squamous Cell Carcinoma

Head and neck cancers are a heterogeneous group of neoplasms, affecting an ever increasing global population. Despite advances in diagnostic technology and surgical approaches to manage these conditions, survival rates have only marginally improved and this has occurred mainly in developed countries. Some improvements in survival, however, have been a result of new management and treatment approaches made possible because of our ever-increasing understanding of the molecular pathways triggered in head and neck oncogenesis, and the growing understanding of the abundant heterogeneity of this group of cancers. Some important pathways are common to other solid tumours, but their impact on reducing the burden of head and neck disease has been less than impressive. Other less known and little-explored pathways may hold the key to the development of potential druggable targets. The extensive work carried out over the last decade, mostly utilising next generation sequencing has opened up the development of many novel approaches to head and neck cancer treatment. This paper explores our current understanding of the molecular pathways of this group of tumours and outlines associated druggable targets which are deployed as therapeutic approaches in head and neck oncology with the ultimate aim of improving patient outcomes and controlling the personal and economic burden of head and neck cancer.

Nanomedicines functionalized with anti-EGFR ligands for active targeting in cancer therapy: Biological strategy, design and quality control

Recently, active targeting using nanocarriers with biological ligands has emerged as a novel strategy for improving the delivery of therapeutic and/or imaging agents to tumor cells. The presence of active targeting moieties on the surface of nanomedicines has been shown to play an important role in enhancing their accumulation in tumoral cells and tissues versus healthy ones. This property not only helps to increase the therapeutic index but also to minimize possible side effects of the designed nanocarriers. Since the overexpression of epidermal growth factor receptors (EGFR) is a common occurrence linked to the progression of a broad variety of cancers, the potential application of anti-EGFR immunotherapy and EGFR-targeting ligands in active targeting nanomedicines is getting increasing attention. Henceforth, the EGFR-targeted nanomedicines were extensively studied in vitro and in vivo but exhibited both satisfactory and disappointing results, depending on used protocols. This review is designed to give an overview of a variety of EGFR-targeting ligands available for nanomedicines, how to conjugate them onto the surface of nanoparticles, and the main analytical methods to confirm this successful conjugation.

A Reliable and Standardizable Differential PCR and qPCR Methodology Assesses HER2 Gene Amplification in Gastric Cancer

We have applied two PCR techniques, differential PCR (diffPCR) and qPCR for the identification of HER2 gene amplifications in genomic DNA of tumor and distal gastric samples from patients with gastric cancer. The diffPCR technique consists of the simultaneous amplification of the HER2 gene and a housekeeping gene by conventional PCR and the densitometric analysis of the bands obtained. We established a cut-off point based on the mean and standard deviation analyzing the DNA of 30 gastric tissues from patients undergoing non-cancer gastrectomy. diffPCR and qPCR yielded consistent results. HER2-overexpression was detected in 25% of patients and was further confirmed by immunohistochemistry and immunofluorescence. The approaches herein described may serve as complementary and reliable methods to assess HER2 amplification.

TDO2 overexpression correlates with poor prognosis, cancer stemness, and resistance to cetuximab in bladder cancer

Background

Bladder cancer (BC) is the 10th most common cancer in the world. BC with muscle invasion results in a poor prognosis and is usually fatal. Cancer cell metabolism has an essential role in the development and progression of tumors. Expression of tryptophan 2,3‐dioxygenase (TDO2) is associated with tumor progression and worse survival in some other cancers. However, no studies have been performed to uncover the biofunctional roles of TDO2 in BC.

Aim

This study aim to investigate the clinicopathologic significance of TDO2 in BC.

Methods and results

TDO2 expression was evaluated by qRT‐PCR and immunohistochemistry in an integrated analysis with the Cancer Genome Atlas (TCGA) and other published datasets. TDO2 overexpression was significantly associated with T classification, N classification, and M classification, tumor stage, recurrence, and basal type, and with the expression of CD44 and aldehyde dehydrogenase 1 (ALDH1) in BC. High TDO2 expression correlated with poor outcome of BC patients. Using BC cell lines with knockdown and forced expression of TDO2, we found that TDO2 was involved in the growth, migration, and invasiveness of BC cells. Moreover, TDO2 was found to be crucial for spheroid formation in BC cells. Importantly, TDO2 promoted BC cells resistance to cetuximab through integration of the EGFR pathway.

Conclusion

Our results indicate that TDO2 might take an essential part in BC progression and could be a potential marker for targeted therapy in BC.

HER2-targeted therapies in gastric cancer

Molecular targeted therapy of cancer has always been the focus of clinicians. Among those therapeutic targets, the human epidermal growth factor receptor-2 (HER-2) signaling pathway is one of the most popular targets for translational research in cancer. However, unlike prospect in breast cancer, HER-2 inhibitor trastuzumab is the only molecular targeted drug approved by US Food and Drug Administration (FDA) for the first-line treatment of HER-2 positive advanced gastric cancer. On this basis, a variety of novel HER2- targeted drugs for gastric cancer are under development, and related clinical researches are in full swing, including small molecular kinase inhibitors (e.g., afatinib, neratinib, pyrotinib), antibody-drug conjugates (e.g., DS-8201a, RC48-ADC) and other novel therapies (e.g., ZW25, CAR-T, BVAC-B). In this study, we will summarize the recent advances in anti-HER-2 agents, potential mechanisms of resistance to HER2-targeted therapy in HER2-positive gastric cancer. We will also discuss the future prospects of potential strategies to overcome anti-HER-2 resistance and development of novel anti-HER-2 approaches for the treatment of HER2-positive gastric cancer patients.

The Anti-PD-1/PD-L1 Immunotherapy for Gastric Esophageal Cancer: A Systematic Review and Meta-Analysis and Literature Review

Background:

Treatment options for advanced gastric esophageal cancer are quite limited. Chemotherapy is unavoidable at certain stages, and research on targeted therapies has mostly failed. The advent of immunotherapy has brought hope for the treatment of advanced gastric esophageal cancer. The aim of the study was to analyze the safety of anti-PD-1/PD-L1 immunotherapy and the long-term survival of patients who were diagnosed as gastric esophageal cancer and received anti-PD-1/PD-L1 immunotherapy.

Method:

Studies on anti-PD-1/PD-L1 immunotherapy of advanced gastric esophageal cancer published before February 1, 2020 were searched online. The survival (e.g. 6-month overall survival, 12-month overall survival (OS), progression-free survival (PFS), objective response rates (ORR)) and adverse effects of immunotherapy were compared to that of control therapy (physician’s choice of therapy).

Results:

After screening 185 studies, 4 comparative cohort studies which reported the long-term survival of patients receiving immunotherapy were included. Compared to control group, the 12-month survival (OR = 1.67, 95% CI: 1.31 to 2.12, P < 0.0001) and 18-month survival (OR = 1.98, 95% CI: 1.39 to 2.81, P = 0.0001) were significantly longer in immunotherapy group. The 3-month survival rate (OR = 1.05, 95% CI: 0.36 to 3.06, P = 0.92) and 18-month survival rate (OR = 1.44, 95% CI: 0.98 to 2.12, P = 0.07) were not significantly different between immunotherapy group and control group. The ORR were not significantly different between immunotherapy group and control group (OR = 1.54, 95% CI: 0.65 to 3.66, P = 0.01). Meta-analysis pointed out that in the PD-L1 CPS ≥10 sub group population, the immunotherapy could obviously benefit the patients in tumor response rates (OR = 3.80, 95% CI: 1.89 to 7.61, P = 0.0002).

Conclusion:

For the treatment of advanced gastric esophageal cancer, the therapeutic efficacy of anti-PD-1/PD-L1 immunotherapy was superior to that of chemotherapy or palliative care.

Eradication of Helicobacter pylori and Gastric Cancer: A Controversial Relationship

Worldwide, gastric cancer (GC) represents the fifth cancer for incidence, and the third as cause of death in developed countries. Indeed, it resulted in more than 780,000 deaths in 2018. Helicobacter pylori appears to be responsible for the majority of these cancers. On the basis of recent studies, and either alone or combined with additional etiological factors, H. pylori is considered a “type I carcinogen.” Over recent decades, new insights have been obtained into the strategies that have been adopted by H. pylori to survive the acidic conditions of the gastric environment, and to result in persistent infection, and dysregulation of host functions. The multistep processes involved in the development of GC are initiated by transition of the mucosa into chronic non-atrophic gastritis, which is primarily triggered by infection with H. pylori. This gastritis then progresses into atrophic gastritis and intestinal metaplasia, and then to dysplasia, and following Correa’s cascade, to adenocarcinoma. The use of antibiotics for eradication of H. pylori can reduce the incidence of precancerous lesions only in the early stages of gastric carcinogenesis. Here, we first survey the etiology and risk factors of GC, and then we analyze the mechanisms underlying tumorigenesis induced by H. pylori, focusing attention on virulence factor CagA, inflammation, oxidative stress, and ErbB2 receptor tyrosine kinase. Moreover, we investigate the relationships between H. pylori eradication therapy and other diseases, considering not only cardia (upper stomach) cancers and Barrett’s esophagus, but also asthma and allergies, through discussion of the “hygiene hypothesis. ” This hypothesis suggests that improved hygiene and antibiotic use in early life reduces microbial exposure, such that the immune response does not become primed, and individuals are not protected against atopic disorders, asthma, and autoimmune diseases. Finally, we overview recent advances to uncover the complex interplay between H. pylori and the gut microbiota during gastric carcinogenesis, as characterized by reduced bacterial diversity and increased microbial dysbiosis. Indeed, it is of particular importance to identify the bacterial taxa of the stomach that might predict the outcome of gastric disease through the stages of Correa’s cascade, to improve prevention and therapy of gastric carcinoma.

The NRG3/ERBB4 signaling cascade as a novel therapeutic target for canine glioma

Canine glioma is a common brain tumor with poor prognosis despite surgery and/or radiation therapy. Therefore, newer and more effective treatment modalities are needed. Neuregulin 3 (NRG3) has known to be a ligand of ERBB4. This study aimed to investigate the usefulness of the NRG3/ERBB4 signaling cascade as a novel therapeutic target in canine glioma. We found out that microRNA (miR)-190a was downregulated in canine brain tumor tissues, including glioma and meningioma. miR-190a directly targeted NRG3 and inhibited the growth of canine glioma cells. The level of p-Akt, which is a downstream target of ERBB4 signaling, was decreased by transfection with miR-190a. NRG3 silencing also suppressed cell growth and decreased the levels of p-Akt and p-ERK1/2, and NRG3 overexpression exhibited opposed effects in canine glioma J3T-1 cells. The mRNA level of erbb4 was significantly upregulated in glioma tissues compared with that in normal brain tissues and meningioma tissues. Furthermore, compared with gefitinib and lapatinib, afatinib exerted a greater inhibitory effect on the growth of canine glioma cells. In conclusion, NRG3/ERBB4 signaling is negatively regulated by miR-190a and contributes to the growth of canine glioma cells, indicating that it may be a promising therapeutic target in canine glioma.

Inhibition of Glutamine Uptake Improves the Efficacy of Cetuximab on Gastric Cancer

Treatment for advanced gastric cancer is challenging. Epidermal growth factor receptor (EGFR) contributes to the proliferation and development of gastric cancer (GC), and its overexpression is associated with unfavorable prognosis in GC. Cetuximab, a monoclonal antibody targeting EGFR, failed to improve the overall survival of gastric cancer patients indicated in phase III randomized trials. Glutamine is a vital nutrient for tumor growth and its metabolism contributes to therapeutic resistance, making glutamine uptake an attractive target for cancer treatment. The aim of the present study was to investigate whether intervention of glutamine uptake could improve the effect of cetuximab on GC. The results of MTT assay showed that by glutamine deprivation or inhibition of glutamine uptake, the viability of gastric carcinoma cells was inhibited more severely than that of human immortal gastric mucosa epithelial cells (GES-1). The expression of the key glutamine transporter alanine-serine-cysteine (ASC) transporter 2 (ASCT2; SLC1A5) was significantly higher in gastric carcinoma tissues and various gastric carcinoma cell lines than in normal gastric tissues and cells, as shown by immunohistochemistry and western blotting, while silencing ASCT2 significantly inhibited the viability and proliferation of gastric carcinoma cells. Consistent with previous studies, it was shown herein by MTT and EdU assays that cetuximab had a weak inhibitory effect on the cell viability of gastric carcinoma cells. However, inhibiting glutamine uptake by blockade of ASCT2 with l-γ-glutamyl-p-nitroanilide (GPNA) significantly enhanced the inhibitory effect of cetuximab on suppressing the proliferation of gastric cancer both in vitro and in vivo. Moreover, combining cetuximab and GPNA induced cell apoptosis considerably in gastric carcinoma cells, as shown by flow cytometry, and had a higher depressing effect on gastric cancer proliferation both in vitro and in vivo, as compared to either treatment alone. The present study suggested that inhibition of glutamine uptake may be a promising strategy for improving the inhibitory efficacy of cetuximab on advanced gastric cancer.

Type 2 diabetes mellitus facilitates endometrial hyperplasia progression by activating the proliferative function of mucin O-glycosylating enzyme GALNT2

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is thought to be a risk factor for endometrial hyperplasia, but potential links between the two diseases are unknown. This study aims to evaluate the role of T2DM in the progression of endometrial hyperplasia.

METHODS

Female Sprague-Dawley rats were randomly divided into normal (N) group, endometrial hyperplasia (NH) group, T2DM (T) group, and endometrial hyperplasia with T2DM (TH) group. Proteomics analysis was performed to determine the protein profile of endometrial tissues. Proliferation, migration, and invasion of cells with/without GLANT2-knockdown were assessed. Immunohistochemical staining and ELISA were used to examine the expression of GALNT2 in endometrial tissues and serum of clinical samples.

RESULTS

The highest uterus index and endometrial thickness were observed in TH group, with the expression of proliferation marker PCNA increased significantly, indicating that T2DM facilitates the progress of endometrial hyperplasia. Proteomics analysis showed that there were significant differences in protein profiles among groups and differential proteins were mainly enriched in metabolic pathways. Further verification by molecular biology analysis indicated that GALNT2 is the key target for T2DM facilitating endometrial hyperplasia. The expression of GALNT2 was significantly decreased in high glucose environment. T2DM could synergize the proliferative function of GALNT2 aberration by activating EGFR/AKT/ERK pathway. The decreased expressions of GALNT2 in clinical samples were associated with worse subtypes of endometrial hyperplasia.

CONCLUSION

T2DM promoted the progression of endometrial hyperplasia by regulating the GALNT2-mediated phosphorylation of EGFR and enhancing cell proliferation. GALNT2 has the potential to be a novel biomarker in the treatment of endometrial hyperplasia.

Structural Perspectives on Extracellular Recognition and Conformational Changes of Several Type-I Transmembrane Receptors

Type-I transmembrane proteins represent a large group of 1,412 proteins in humans with a multitude of functions in cells and tissues. They are characterized by an extracellular, or luminal, N-terminus followed by a single transmembrane helix and a cytosolic C-terminus. The domain composition and structures of the extracellular and intercellular segments differ substantially amongst its members. Most of the type-I transmembrane proteins have roles in cell signaling processes, as ligands or receptors, and in cellular adhesion. The extracellular segment often determines specificity and can control signaling and adhesion. Here we focus on recent structural understanding on how the extracellular segments of several diverse type-I transmembrane proteins engage in interactions and can undergo conformational changes for their function. Interactions at the extracellular side by proteins on the same cell or between cells are enhanced by the transmembrane setting. Extracellular conformational domain rearrangement and structural changes within domains alter the properties of the proteins and are used to regulate signaling events. The combination of structural properties and interactions can support the formation of larger-order assemblies on the membrane surface that are important for cellular adhesion and intercellular signaling.

Therapeutic Implications of Epidermal Growth Factor Receptor (EGFR) in the Treatment of Metastatic Gastric/GEJ Cancer

Gastric cancer remains third leading cause of global cancer mortality and is the fifth most common type of cancer in the United States. A select number of gastric cancers harbor alterations in EGFR and/or have amplification/overexpression in the HER2; 2-35 and 9-38%, respectively. The advent of next-generation sequencing of tissue and circulating tumor DNA has allowed for the massive expansion of targeted therapeutics to be employed in many settings. There have been a handful of trials using EGFR inhibitors with modest outcomes. Using novel strategies to target multiple co-mutations as well as identifying immunoregulatory molecule expression patterns will potentially drive future trials and improve gastric cancer patient outcomes.

Reactive oxygen species and enzyme dual-responsive biocompatible drug delivery system for targeted tumor therapy

Spurred by newly developed drug delivery systems (DDSs), side effects of cancer chemotherapy could be reduced by using multifunctional nanoplatforms. However, the facile synthesis of effective DDSs remains a challenge. Here, a six-arginine-tailed anti-epidermal growth factor receptor (EGFR) affibody was employed to easily synthesize the highly reactive oxygen species (hROS)- and trypsin-responsive 11-mercaptoundecanoic acid-modified gold nanoclusters (MUA-Au NCs) for tumor-targeted drug delivery. The polyarginine moiety of affibody sealed methotrexate (MTX)-loaded MUA-Au NCs through charge effect, as well as leaving the rest targeting fragment of the affibody to specifically bind tumor overexpressed EGFR. As the shell of MUA-Au NCs-MTX-Affibody (MAMA), polyarginine chains of affibody could be digested by trypsin, helping to release MTX from MAMA. The released MTX accelerated destroying MUA-Au NCs through inducing the generation of hROS. Specifically targeting EGFR-overexpressed tumors, quickly delivering a sufficient amount of drug to the tumor, subsequently increasing the local MTX and hROS levels, and safely eliminating the biocompatible structure from kidney, endowed MAMA greater treatment effectiveness and lower side effect than chemotherapy, especially in pancreatic cancer due to its high trypsin level. This simply fabricated DDS may find applications in high effective cancer therapy, especially for tumors with high trypsin activity.

Hierarchical Micro-Nano Topography Promotes Cell Adhesion and Osteogenic Differentiation via Integrin α2-PI3K-AKT Signaling Axis

Surface topography dictates important aspects of cell biological behaviors. In our study, hierarchical micro-nano topography (SLM-AHT) with micro-scale grooves and nano-scale pores was fabricated and compared with smooth topography (S) and irregular micro-scale topography (SLA) surfaces to investigate mechanism involved in cell-surface interactions. Integrin α2 had a higher expression level on SLM-AHT surface compared with S and SLA surfaces, and the expression levels of osteogenic markers icluding Runx2, Col1a1, and Ocn were concomitantly upregulated on SLM-AHT surface. Moreover, formation of mature focal adhesions were significantly enhanced in SLM-AHT group. Noticablely, silencing integrin α2 could wipe out the difference of osteogenic gene expression among surfaces with different topography, indicating a crucial role of integrin α2 in topography induced osteogenic differentiation. In addition, PI3K-AKT signaling was proved to be regulated by integrin α2 and consequently participate in this process. Taken together, our findings illustrated that integrin α2-PI3K-AKT signaling axis plays a key role in hierarchical micro-nano topography promoting cell adhesion and osteogenic differentiation.

Natural Killer Cell Responses in Hepatocellular Carcinoma: Implications for Novel Immunotherapeutic Approaches

Hepatocellular carcinoma (HCC) still represents a significant complication of chronic liver disease, particularly when cirrhosis ensues. Current treatment options include surgery, loco-regional procedures and chemotherapy, according to specific clinical practice guidelines. Immunotherapy with check-point inhibitors, aimed at rescuing T-cells from exhaustion, has been applied as second-line therapy with limited and variable success. Natural killer (NK) cells are an essential component of innate immunity against cancer and changes in phenotype and function have been described in patients with HCC, who also show perturbations of NK activating receptor/ligand axes. Here we discuss the current status of NK cell treatment of HCC on the basis of existing evidence and ongoing clinical trials on adoptive transfer of autologous or allogeneic NK cells ex vivo or after activation with cytokines such as IL-15 and use of antibodies to target cell-expressed molecules to promote antibody-dependent cellular cytotoxicity (ADCC). To this end, bi-, tri- and tetra-specific killer cell engagers are being devised to improve NK cell recognition of tumor cells, circumventing tumor immune escape and efficiently targeting NK cells to tumors. Moreover, the exciting technique of chimeric antigen receptor (CAR)-engineered NK cells offers unique opportunities to create CAR-NK with multiple specificities along the experience gained with CAR-T cells with potentially less adverse effects.

IntegrinB5 upregulated by HER2 in gastric cancer: a promising biomarker for liver metastasis

Background

Liver is the most frequent metastatic site of gastric cancer (GC), especially in patients with HER2 positive GC. Exosomal integrin αvβ5 has been shown to promote liver metastasis (LM), and the cross talk between integrins and HER2 during breast cancer metastasis has been reported. However, whether there's an association between HER2 and integrin αvβ5 (ITGAvB5), and whether their association has predictive value in GC liver metastasis (GCLM) remains unknown.

Methods

The association between ITGβ5 and HER2 were accessed by RT-PCR, western blot and ELISA. We tested the function of ITGβ5 on HER2 positive GC cells using Transwell assays and scratch assays. Besides, we detect ITGβ5 expression in tumor tissue of GC patients and exosomes derived from advanced GC to analyze the association between HER2 and LM.

Results

In our study, we found that ITGβ5, rather than ITGAV, was highly upregulated by HER2 through PI3K-AKT pathways in HER2 positive GC. Overexpression of ITGβ5 promoted the migration and invasion of HER2 positive GC cells in vitro. ITGβ5 was found to be an independent prognostic factor for GC. Besides, ITGβ5 level was only associated with LM. Detection of exosomal ITGβ5 and HER2 in the serum of GC patients revealed that exosomal ITGβ5 and HER2 levels are in accordance with that in tissue, and exosomal ITGβ5 level was higher in GCLM than other metastasis.

Conclusions

Our study demonstrated ITGβ5 is regulated and functions in accordance with HER2 in promoting GCLM. Exosomal ITGβ5 levels might be a potential liquid biopsy biomarker for GCLM.

Regulation of aberrantly expressed SERPINH1 by antitumor miR-148a-5p inhibits cancer cell aggressiveness in gastric cancer

RNA-sequencing-based microRNA (miRNA) expression signatures have revealed that miR-148a-5p (the passenger strand of the miR-148a-duplex) is downregulated in various kinds of cancer tissues. Analysis of The Cancer Genome Atlas (TCGA) database showed that low expression of miR-148a-5p was predictive of a lower survival rate (p = 0.041) in patients with gastric cancer (GC). Downregulation of miR-148a-5p was confirmed in GC clinical specimens, and its ectopic expression attenuated GC cell proliferation. Our search for miRNA target genes identified a total of 18 oncogenic targets of miR-148a-5p in GC cells. Among these targets, high expression levels of six genes (THBS2, P4HA3, SERPINH1, CDH11, BCAT1, and KCNG3) were closely associated with a poor prognosis (10-year survival rates) in GC patients (p < 0.05) according to TCGA database analyses. Furthermore, we focused on SERPINH1 as a chaperone protein involved in collagen folding in humans. Aberrant expression of SERPINH1 (mRNA and protein levels) was confirmed in GC clinical specimens. Knockdown assays of SERPINH1 using siRNAs resulted in inhibition of the aggressive phenotype of GC cells. Exploring the molecular networks controlled by miRNAs (including miRNA passenger strands) will broaden our understanding of the molecular pathogenesis of GC.

PDGFD induces ibrutinib resistance of diffuse large B‑cell lymphoma through activation of EGFR

Ibrutinib, an FDA approved, orally administered BTK inhibitor, has demonstrated high response rates to diffuse large B-cell lymphoma (DLBCL), however, complete responses are infrequent and acquired resistance to BTK inhibition can emerge. The present study investigated the role of the platelet-derived growth factor D (PDGFD) gene and the ibrutinib resistance of DLBCL in relation to epidermal growth factor receptor (EGFR). Bioinformatics was used to screen and analyze differentially expressed genes (DEGs) in complete response (CR), partial response (PR) and stable disease (SD) in DLBCL treatment with ibrutinib, and Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to analyze enriched the signaling pathways increasing DEGs. The Search Tool for Interactions of Chemicals database was used to analyze the target genes of ibrutinib. An interaction network of DEGs, disease-related genes and ibrutinib was constructed. The expression of PDGFD in tissues that were resistant or susceptible to DLBCL/ibrutinib was detected via immunohistochemistry (IHC), and the expression of PDGFD in DLBCL/ibrutinib-resistant strains and their parental counterparts were examined via reverse transcription-quantitative PCR and western blot analyses. Subsequently, a drug-resistant cell model of DLBCL/ibrutinib in which PDGFD was silenced was constructed. The apoptosis of the DLBCL/ibrutinib-resistant strains was examined using MTT and flow cytometry assays. EGFR gene expression was then assessed. At the same time, a PDGFD-interfering plasmid and an EGFR overexpression plasmid were transfected into the DLBCL drug-resistant cells (TMD8-ibrutinib, HBL1-ibrutinib) separately or together. MTT was used to measure cell proliferation and changes in the IC₅₀ of ibrutinib. A total of 86 DEGs that increased in the CR, PR and SD tissues were screened, and then evaluated with GO and KEGG. The interaction network diagram showed that there was a regulatory relationship between PDGFD and disease-related genes, and that PDGFD could indirectly target the ibrutinib target gene EGFR, indicating that PDGFD could regulate DLBCL via EGFR. IHC results showed high expression of PDGFD in diffuse large B-cell lymphoma tissues with ibrutinib tolerance. PDGFD expression in ibrutinib-resistant DLBCL cells was higher compared with in parental cells. Following interference with PDGFD expression in ibrutinib-resistant DLBCL cells, the IC₅₀ value of ibrutinib decreased, the rate of apoptosis increased and EGFR expression decreased. In brief, EGFR overexpression can reverse the resistance of DLBCL to ibrutinib via PDGFD interference, and PDGFD induces the resistance of DLBCL to ibrutinib via EGFR.

Helicobacter Pylori Targets the EPHA2 Receptor Tyrosine Kinase in Gastric Cells Modulating Key Cellular Functions

Helicobacter pylori, a stomach-colonizing Gram-negative bacterium, is the main etiological factor of various gastroduodenal diseases, including gastric adenocarcinoma. By establishing a life-long infection of the gastric mucosa, H. pylori continuously activates host-signaling pathways, in particular those associated with receptor tyrosine kinases. Using two different gastric epithelial cell lines, we show that H. pylori targets the receptor tyrosine kinase EPHA2. For long periods of time post-infection, H. pylori induces EPHA2 protein downregulation without affecting its mRNA levels, an effect preceded by receptor activation via phosphorylation. EPHA2 receptor downregulation occurs via the lysosomal degradation pathway and is independent of the H.pylori virulence factors CagA, VacA, and T4SS. Using small interfering RNA, we show that EPHA2 knockdown affects cell–cell and cell–matrix adhesion, invasion, and angiogenesis, which are critical cellular processes in early gastric lesions and carcinogenesis mediated by the bacteria. This work contributes to the unraveling of the underlying mechanisms of H. pylori–host interactions and associated diseases. Additionally, it raises awareness for potential interference between H. pylori infection and the efficacy of gastric cancer therapies targeting receptors tyrosine kinases, given that infection affects the steady-state levels and dynamics of some receptor tyrosine kinases (RTKs) and their signaling pathways.