Forty-nine gastric cancer cell lines with integrative genomic profiling for development of c-MET inhibitor

Ferroptosis regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer

BACKGROUND

Gastric cancer is one of the most common malignant tumors in the world, and its occurrence and development involve complex biological processes. Iron death, as a new cell death mode, has attracted wide attention in recent years. However, the regulatory mechanism of iron death in gastric cancer and its effect on lipid peroxidation metabolism remain unclear.

AIM

To explore the role of iron death in the development of gastric cancer, reveal its relationship with lipid peroxidation, and provide a new theoretical basis for revealing the molecular mechanism of the occurrence and development of gastric cancer.

METHODS

The process of iron death in gastric cancer cells was simulated by cell culture model, and the occurrence of iron death was detected by fluorescence microscopy and flow cytometry. The changes of gene expression related to iron death and lipid peroxidation metabolism were analyzed by high-throughput sequencing technology. In addition, a mouse model of gastric cancer was established, and the role of iron death in vivo was studied by histology and immunohistochemistry, and the level of lipid peroxidation was detected. These methods comprehensively and deeply reveal the regulatory mechanism of iron death on lipid peroxidation metabolism in the occurrence and development of gastric cancer.

RESULTS

Iron death was significantly activated in gastric cancer cells, and at the same time, associated lipid peroxidation levels increased significantly. Through high-throughput sequencing analysis, it was found that iron death regulated the expression of several genes related to lipid metabolism. In vivo experiments demonstrated that increased iron death in gastric cancer mice was accompanied by a significant increase in lipid peroxidation.

CONCLUSION

This study confirmed the important role of iron death in regulating lipid peroxidation metabolism in the occurrence and development of gastric cancer. The activation of iron death significantly increased lipid peroxidation levels, revealing its regulatory mechanism inside the cell.

Characterization of MET Alterations in 37 Gastroesophageal Cancer Cell Lines for MET-Targeted Therapy

Capmatinib and savolitinib, selective MET inhibitors, are widely used to treat various MET-positive cancers. In this study, we aimed to determine the effects of these inhibitors on MET-amplified gastric cancer (GC) cells. Methods: After screening 37 GC cell lines, the following cell lines were found to be MET-positive with copy number variation >10: SNU-620, ESO51, MKN-45, SNU-5, and OE33 cell lines. Next, we assessed the cytotoxic response of these cell lines to capmatinib or savolitinib alone using cell counting kit-8 and clonogenic cell survival assays. Western blotting was performed to assess the effects of capmatinib and savolitinib on the MET signaling pathway. Xenograft studies were performed to evaluate the in vivo therapeutic efficacy of savolitinib in MKN-45 cells. Savolitinib and capmatinib exerted anti-proliferative effects on MET-amplified GC cell lines in a dose-dependent manner. Savolitinib inhibited the phosphorylation of MET and downstream signaling pathways, such as the protein kinase B (AKT) and extracellular signal-regulated kinase (ERK) pathways, in MET-amplified GC cells. Additionally, savolitinib significantly decreased the number of colonies formed on the soft agar and exerted dose-dependent anti-tumor effects in an MKN-45 GC cell xenograft model. Furthermore, a combination of trastuzumab and capmatinib exhibited enhanced inhibition of AKT and ERK activation in human epidermal growth factor receptor-2 (HER2)- and MET-positive OE33 cells. Targeting MET with savolitinib and capmatinib efficiently suppressed the growth of MET-amplified GC cells. Moreover, these MET inhibitors exerted synergistic effects with trastuzumab on HER2- and MET-amplified GC cells.

Expressions and Clinical Significance of Met and YAP in Gastric Cancer Tissue Microarray

Objective

This study is aimed at investigating the expression of Met and YAP in gastric cancer and their impact on clinical prognosis.

Methods

Tissue samples and clinical data were collected from 89 patients with gastric cancer. Immunohistochemistry was performed to quantify the expression of Met and YAP using tissue microarray. The correlation between the expressions of Met, YAP, and clinicopathological characteristics of patients was determined using a chi-square test. Survival analysis was conducted using the Kaplan-Meier method, while multivariate survival analysis was performed using the Cox proportional hazard model. Bioinformatics analysis was carried out by downloading chip data from TCGA.

Results

The expression levels of both Met and YAP were significantly higher in gastric cancer tissues compared to adjacent tissues (P < 0.001). Met expression showed a positive association with P53 and CD133, whereas YAP expression correlated positively with tumor grade and CD133 (P < 0.05). Pearson's analysis revealed a significant correlation between Met expression and VEGFR as well as CD133, while YAP expression correlated with Ki67 and VEGFR (P < 0.05). Patients with high levels of both Met and YAP exhibited decreased survival time (P < 0.01). Furthermore, Met expression, N stage, and VEGFR were identified as independent risk factors for gastric cancer prognosis (P < 0.05), whereas no such association was observed for YAP expression. Bioinformatics analysis demonstrated a significant correlation between the expressions of Met and YAP; both proteins were highly expressed in gastric cancer patients accompanied by markedly reduced survival time.

Conclusion

The expressions of Met and YAP are closely associated with the survival outcomes as well as clinicopathological features in patients with gastric cancer. Moreover, our findings highlight that Met serves as an independent prognostic factor for gastric cancer.

Novel HER2-targeted therapy to overcome trastuzumab resistance in HER2-amplified gastric cancer

Trastuzumab is used to treat HER2-amplified metastatic gastric cancer; however, most patients become trastuzumab-resistant within a year. Knowledge of the mechanisms underlying trastuzumab resistance is required to overcome this limitation. Here, we aimed to elucidate this resistance mechanism using four trastuzumab-resistant (TR) cell lines and investigate the efficacy of HER2-targeted therapies to overcome treatment resistance. Each TR cell line had different phenotypic characteristics. Interestingly, HER2 expression remained as high as the parental cell lines in TR cell lines, suggesting that HER2-targeted agents were still useful. As expected, three tyrosine kinase inhibitors (lapatinib, neratinib, and tucatinib) and one antibody-drug conjugate (trastuzumab deruxtecan: T-DXd) exhibited good antitumor effects against TR cell lines. We further investigated the potential biological mechanism of T-DXd. When treated with trastuzumab or T-DXd, HER2 or its downstream signals were disrupted in parental cell lines, but not in TR cell lines. Moreover, T-DXd induced the expression of pH2A.X and cPARP and caused cell cycle arrest in the S or G2-M phase in TR cell lines. T-DXd showed promising antitumor activity in both parental and TR cell lines, suggesting that it is a potential candidate for overcoming trastuzumab resistance.

Patient-derived exosomes facilitate therapeutic targeting of oncogenic MET in advanced gastric cancer

Gastric cancer (GC) with peritoneal metastases and malignant ascites continues to have poor prognosis. Exosomes mediate intercellular communication during cancer progression and promote therapeutic resistance. Here, we report the significance of exosomes derived from malignant ascites (EXOAscites) in cancer progression and use modified exosomes as resources for cancer therapy. EXOAscites from patients with GC stimulated invasiveness and angiogenesis in an ex vivo three-dimensional autologous tumor spheroid microfluidic system. EXOAscites concentration increased invasiveness, and blockade of their secretion suppressed tumor progression. In MET-amplified GC, EXOAscites contain abundant MET; their selective delivery to tumor cells enhanced angiogenesis and invasiveness. Exosomal MET depletion substantially reduced invasiveness; an additive therapeutic effect was induced when combined with MET and/or VEGFR2 inhibition in a patient-derived MET-amplified GC model. Allogeneic MET-harboring exosome delivery induced invasion and angiogenesis in a MET non-amplified GC model. MET-amplified patient tissues showed higher exosome concentration than their adjacent normal tissues. Manipulating exosome content and production may be a promising complementary strategy against GC.

Trastuzumab Combined With Ramucirumab and Paclitaxel in Patients With Previously Treated Human Epidermal Growth Factor Receptor 2-Positive Advanced Gastric or Gastroesophageal Junction Cancer

PURPOSE

Trastuzumab-containing chemotherapy is the recommended first-line regimen for human epidermal growth factor receptor 2 (HER2)-positive advanced gastric or gastroesophageal junction (G/GEJ) cancer. We evaluated the safety and efficacy of trastuzumab combined with ramucirumab and paclitaxel as second-line treatment for HER2-positive G/GEJ cancer.

PATIENTS AND METHODS

Patients with HER2-positive advanced G/GEJ cancer who progressed after first-line treatment with trastuzumab-containing chemotherapy were enrolled from five centers in the Republic of Korea. Patients were administered a 28-day cycle of trastuzumab (once on days 1, 8, 15, and 22: 2 mg/kg followed by 4 mg/kg loading dose), ramucirumab (once on days 1 and 15: 8 mg/kg), and paclitaxel (once on days 1, 8, and 15: dose level 1, 80 mg/m2; or dose level -1, 70 mg/m2). Phase II was conducted with the recommended phase II dose (RP2D). Primary end points were determination of RP2D during phase Ib and investigator-assessed progression-free survival (PFS) in patients treated with RP2D.

RESULTS

Dose-limiting toxicity at dose level 1 was not documented during phase Ib, and a full dose combination was selected as the RP2D. Among 50 patients with a median follow-up duration of 27.5 months (95% CI, 17.4 to 37.6), median PFS and overall survival were 7.1 months (95% CI, 4.8 to 9.4) and 13.6 months (95% CI, 9.4 to 17.7), respectively. Objective response rate was 54% (27 of 50, including one complete response), and disease control rate was 96% (48 of 50). Loss of HER2 expression was observed in 34.8% (8 of 23) patients after first-line treatment, and no definite association between HER2 expression and the outcome was revealed. Safety profiles were consistent with previous reports.

CONCLUSION

Trastuzumab combined with ramucirumab and paclitaxel showed appreciable efficacy with manageable safety profiles in patients with previously treated HER2-positive G/GEJ cancer.

Analytical and Clinical Validation of Cell-Free Circulating Tumor DNA Assay for the Estimation of Tumor Mutational Burden

Background

Ultra-deep sequencing to detect low-frequency mutations in circulating tumor-derived DNA (ctDNA) increases the diagnostic value of liquid biopsy. The demand for large ctDNA panels for comprehensive genomic profiling and tumor mutational burden (TMB) estimation is increasing; however, few ctDNA panels for TMB have been validated. Here, we designed a ctDNA panel with 531 genes, named TMB500, along with a technical and clinical validation.

Methods

Synthetic reference cell-free DNA materials with predefined allele frequencies were sequenced in a total of 92 tests in 6 batches to evaluate the precision, linearity, and limit of detection of the assay. We used clinical samples from 50 patients with various cancers, 11 healthy individuals, and paired tissue samples. Molecular barcoding and data analysis were performed using customized pipelines.

Results

The assay showed high precision and linearity (coefficient of determination, r2 = 0.87) for all single nucleotide variants, with a limit of detection of 0.24%. In clinical samples, the TMB500 ctDNA assay detected most variants present and absent in tissues, showing that ctDNA could assess tumor heterogeneity in different tissues and metastasis sites. The estimated TMBs correlated well between tissue and blood, except in 4 cases with extreme heterogeneity that showed very high blood TMBs compared to tissue TMBs. A pilot evaluation showed that the TMB500 assay could be used for disease monitoring.

Conclusions

The TMB500 assay is an accurate and reliable ctDNA assay for many clinical purposes. It may be useful for guiding the treatment of cancers with diverse genomic profiles, estimating TMB in immune therapy, and disease monitoring.

Clinicopathological difference between gastric cancer in the lesser curvature and gastric cancer in the greater curvature

Gastric cancer (GC) is a heterogeneous disease; the tumor distribution and molecular subtype could affect the prognosis of patients with GC. However, the clinicopathological difference between GC in the lesser and that in the greater curvature remains unknown. In this study, we aimed to investigate the difference and provide new clues for the treatment of GC. Between January 2010 and August 2014, 1249 consecutive patients with GC in the lesser or greater curvature were treated in our surgery department; data related to the demographic characteristics, pathological type, tumor grade, tumor size, TNM stage, tumor markers, operative methods, complications, and follow-up were retrospectively analyzed using a univariate analysis and the Kaplan-Meier method. The tumor size in lesser curvature was larger than that in the greater curvature (4.95 ± 2.57 vs 4.43 ± 2.62 cm, P = .034); patients with GC in the lesser curvature had a higher incidence of total gastrectomy and a lower incidence of distal gastrectomy than those with GC in the greater curvature (60.2% vs 43.2%, and 34.8% vs 49.2%, P = .002). No significant differences were found in the 5-year survival rate between patients with GC in the greater curvature and those with GC in the lesser curvature (62.6% vs 66.1%, P = .496). The epidermal growth factor receptor (EGFR) expression rate of tumors in the lesser curvature was 40.55%, which was significantly higher than that of tumors in the greater curvature (25.92%, P = .024), while the 5-year survival rate of patients with EGFR-positive expression was 50.8%, which was significantly lower than that of patients with EGFR-negative expression (64.8%, P = .021). Significant differences were observed in the clinicopathological features between GC in the lesser curvature and that in the greater curvature. These differences contribute to the improvement in the treatment outcome.

Receptor Tyrosine Kinases Amplified in Diffuse-Type Gastric Carcinoma: Potential Targeted Therapies and Novel Downstream Effectors

Simple Summary

Diffuse-type gastric carcinoma (DGC) is an aggressive subtype of gastric carcinoma with an extremely poor prognosis due to frequent peritoneal metastasis and high probability of recurrence. Its pathogenesis is poorly understood, and consequently, no effective molecular targeted therapy is available. The importance of oncogenic receptor tyrosine kinase (RTK) signaling has been recently demonstrated in the malignant progression of DGC. In particular, RTK gene amplification appears to accelerate peritoneal metastasis. In this review, we provide an overview of RTK gene amplification in DGC and the potential of related targeted therapies.

Abstract

Gastric cancer (GC) is a major cause of cancer-related death worldwide. Patients with an aggressive subtype of GC, known as diffuse-type gastric carcinoma (DGC), have extremely poor prognoses. DGC is characterized by rapid infiltrative growth, massive desmoplastic stroma, frequent peritoneal metastasis, and high probability of recurrence. These clinical features and progression patterns of DGC substantially differ from those of other GC subtypes, suggesting the existence of specific oncogenic signals. The importance of gene amplification and the resulting aberrant activation of receptor tyrosine kinase (RTK) signaling in the malignant progression of DGC is becoming apparent. Here, we review the characteristics of RTK gene amplification in DGC and its importance in peritoneal metastasis. These insights may potentially lead to new targeted therapeutics.

NDUFC1 Is Upregulated in Gastric Cancer and Regulates Cell Proliferation, Apoptosis, Cycle and Migration

Gastric cancer is one of the most common primary tumors of the digestive system. NADH: ubiquinone oxidoreductase subunit C1 (NDUFC1), which is an accessory subunit of the NADH dehydrogenase (complex I), is responsible for the transportation of electrons from NADH to the respiratory chain essential for the oxidative phosphorylation. However, little is known about the roles of NDUFC1 in carcinogenesis. In this study, NDUFC1 protein level in NSCLC tissues was tested by immunohistochemistry (IHC) staining. NDUFC1 mRNA level in gastric cancer cell lines was determined by qRT-PCR. MGC-803 and SGC-7901 cells were transfected with shNDUFC1 lentivirus designed to silence NDUFC1. MTT assay, CCK8 assay, wound healing assay and transwell migration assay were conducted. Cell cycle and apoptosis were detected by flow cytometry. In vivo experiments were performed using nude mice. The results indicated that overexpressed NDUFC1 in gastric cancer was related to more serious tumor infiltrates, a higher risk of lymphatic metastasis, a higher proportion of positive lymph nodes, and a more advanced tumor stage. Compared with shCtrl groups, MGC-803 and SGC-7901 of shNDUFC1 groups had lower abilities of proliferation and migration, higher levels of apoptosis. NDUFC1 knockdown also inhibited SGC-7901 cell growth in vivo and suppressed Ki67 expression in xenograft tumors. More importantly, we found that NDUFC1 downregulation made the levels of P-Akt, P-mTOR, CCND1, CDK6, PIK3CA, Bcl-2, Survivin, and XIAP decreased, and that PI3K/AKT signaling pathway agonist SC79 rescued the inhibitory effects on cell proliferation and migration, reversed the promoted effects on cell apoptosis caused by NDUFC1 knockdown. More importantly, compared with NDUFC1 knockdown group, the expression of P-Akt, Bcl-2, Survivin, and XIAP was raised in shNDUFC1 + SC79 group. Thus, our suspicion was that NDUFC1 exacerbates NSCLC progression via PI3K/Akt pathway. Taken together, our study indicated that targeting NDUFC1 could open innovative perspectives for new multi-targeting approaches in the treatment of gastric cancer.

LncRNA NR038975, A Serum-Based Biomarker, Promotes Gastric Tumorigenesis by Interacting With NF90/NF45 Complex

Gastric cancer (GC) is one of the deadliest cancers, and long noncoding RNAs (lncRNAs) have been reported to be the important regulators during the occurrence and development of GC. The present study identified a novel and functional lncRNA in GC, named NR038975, which was confirmed to be markedly upregulated in the Gene Expression Profiling Interactive Analysis (GEPIA) dataset and our independent cohort of GC tissues. We firstly characterized the full-length sequence and subcellular location of NR038975 in GC cells. Our data demonstrated that upregulated NR038975 expression was significantly related to lymph node metastasis and TNM stage. In addition, knockdown of NR038975 inhibited GC cell proliferation, migration, invasion, and clonogenicity and vice versa. Mechanistically, RNA pull-down and mass spectrometry assays identified the NR038975-binding proteins and NF90/NF45 complex, and the binding was also confirmed by RNA immunoprecipitation and confocal experiments. We further demonstrated that genetic deficiency of NR038975 abrogated the interaction between NF45 and NF90. Moreover, NF90 increased the stability of NR038975. Thus, NR038975-NF90/NF45 will be an important combinational target of GC. Finally, we detected NR038975 in serum exosomes and serum of GC patients. Our results indicated that NR038975 was a biomarker for gastric tumorigenesis. The current study demonstrated that NR038975 is a novel lncRNA that is clinically and functionally engaged in GC progression and might be a novel diagnostic marker and potential therapeutic target.

Inhibition of the bromodomain and extra-terminal family of epigenetic regulators as a promising therapeutic approach for gastric cancer

PURPOSE

Epigenetic dysregulation is a common characteristic of cancers, including gastric cancer (GC), and contributes to cancer development and progression. Although the efficacy of BET (an epigenetic regulator) inhibition has been demonstrated in various cancer types, predictive genetic markers of its efficacy in GC are currently lacking. Therefore, we aimed to identify markers that predict the response of BET inhibition in GC and, suggest an effective treatment regimen through combined therapy.

METHODS

The effect of BET inhibition was evaluated using iBET-151, a small-molecule inhibitor of BET proteins, in a large panel (n = 49) of GC cell lines and xenograft mouse models. Comprehensive genetic information was used to identify cell lines sensitive to iBET-151. Flow cytometry, Western blotting, and colony-formation and migration assays were used to evaluate the effects of iBET-151 and/or paclitaxel. The synergistic effect of iBET-151 and paclitaxel was evaluated using an organoid model.

RESULTS

We found that iBET-151 showed a modest growth-inhibitory effect in GC cells (73%, 36/49). iBET-151 inhibited tumorigenicity in vitro and significantly promoted cell cycle arrest and apoptosis. Based on comprehensive genetic information analysis in relation to BET family expression, we found that BRD4 was highly expressed in the iBET-151-sensitive cell lines. We also identified WNT5B and IRS2 as potential biomarkers that are predictive for sensitivity to iBET-151. In GC xenograft model mice, iBET-151 significantly decreased tumor volumes and Ki-67 and BRD4 expression. Combination treatment showed that iBET-151 increased the sensitivity of GC cells to paclitaxel in approximately 70% of the cell lines (34/49) tested. iBET-151 plus paclitaxel significantly promoted cell cycle arrest and apoptosis and suppressed c-Myc, Bcl-2 and Bcl-xL expression. In GC organoids, iBET-151 and paclitaxel showed a synergistic effect.

CONCLUSIONS

Collectively, our data suggest that iBET-151 is a potential therapeutic agent for GC, especially in combination with paclitaxel, and that WNT5B and IRS2 may predict iBET-151 sensitivity.

CHSY1 is upregulated and acts as tumor promotor in gastric cancer through regulating cell proliferation, apoptosis, and migration

Gastric cancer is one of the most frequently diagnosed malignant tumors, with rapid progression and poor prognosis. The role of chondroitin sulfate synthase 1 (CHSY1) in the development and progression of gastric cancer was explored and clarified in this study. The immunohistochemistry analysis of clinical tissue samples as well as data mining of public database showed that CHSY1 was significantly upregulated in gastric cancer and associated with more advanced tumor stage and poorer prognosis. In vitro loss-of-function experiments demonstrated the inhibited cell proliferation, colony formation, cell migration, as well as the promoted cell apoptosis by CHSY1 knockdown. Moreover, recovery of CHSY1 expression could attenuate the regulatory effects induced by CHSY1 knockdown. Correspondingly, gastric cancer cells with CHSY1 knockdown showed reduced tumorigenicity and slower tumor growth in vivo. In conclusion, this study identified CHSY1 as a tumor promotor in gastric cancer, which may be utilized as a novel indicator of patients' prognosis and therapeutic target for developing more effective drug for GC treatment.

Oncogenic mechanism-based pharmaceutical validation of therapeutics targeting MET receptor tyrosine kinase

Aberrant expression and/or activation of the MET receptor tyrosine kinase is characterized by genomic recombination, gene amplification, activating mutation, alternative exon-splicing, increased transcription, and their different combinations. These dysregulations serve as oncogenic determinants contributing to cancerous initiation, progression, malignancy, and stemness. Moreover, integration of the MET pathway into the cellular signaling network as an addiction mechanism for survival has made this receptor an attractive pharmaceutical target for oncological intervention. For the last 20 years, MET-targeting small-molecule kinase inhibitors (SMKIs), conventional therapeutic monoclonal antibodies (TMABs), and antibody-based biotherapeutics such as bispecific antibodies, antibody–drug conjugates (ADC), and dual-targeting ADCs have been under intensive investigation. Outcomes from preclinical studies and clinical trials are mixed with certain successes but also various setbacks. Due to the complex nature of MET dysregulation with multiple facets and underlying mechanisms, mechanism-based validation of MET-targeting therapeutics is crucial for the selection and validation of lead candidates for clinical trials. In this review, we discuss the importance of various types of mechanism-based pharmaceutical models in evaluation of different types of MET-targeting therapeutics. The advantages and disadvantages of these mechanism-based strategies for SMKIs, conventional TMABs, and antibody-based biotherapeutics are analyzed. The demand for establishing new strategies suitable for validating novel biotherapeutics is also discussed. The information summarized should provide a pharmaceutical guideline for selection and validation of MET-targeting therapeutics for clinical application in the future.

Lidocaine suppresses the malignant behavior of gastric cancer cells via the c-Met/c-Src pathway

The present study was designed to investigate the role and mechanism of action behind the action of lidocaine in gastric cancer cells. Lidocaine was tested for its potential role in affecting the viability of cells using Cell Counting Kit-8 (CCK-8) assays. It was found that there was a decreased MKN45 cell viability upon lidocaine treatment in a dose-dependent manner. Phosphorylated c-Met, phosphorylated c-Src, c-Met and c-Src levels were detected using western blotting following lidocaine or hepatocyte growth factor (HGF) intervention. It was found that the phosphorylation levels of c-Met and c-Src were markedly reduced by lidocaine treatment, with this effect being further relieved by the addition of HGF. Subsequently, whether lidocaine repressed the malignant biological properties of gastric cancer cells through the c-Met/c-Src axis was further investigated through the detection of epithelial-mesenchymal transition markers (N-caderin and vimentin), wound healing and transwell assay analysis. In addition, cell apoptosis and the levels of apoptosis-related proteins were determined using TUNEL and western blot assays, respectively. The results demonstrated that the malignant behavior of cells were notably repressed upon lidocaine treatment, but the addition of HGF markedly reversed these effects, indicating that the effects of lidocaine on supressing the malignant behaviour of cells could be mediated through the c-Met/c-Src axis. Subsequently, whether lidocaine affected the sensitivity of cells to cisplatin or 5-FU was analyzed using a CCK-8 assay. Enhanced sensitivity of cells to cisplatin or 5-FU was observed when treated in combination with lidocaine. The present study concluded that the involvement of the c-Met/c-Src pathway in the biological behaviour of MKN45 cells was mediated by lidocaine. Therefore, lidocaine may have the potential to suppress the malignant behaviour and proliferation of gastric cancer cells.

Transcriptome analysis of iBET-151, a BET inhibitor alone and in combination with paclitaxel in gastric cancer cells

BET inhibitor, as an epigenetic regulator inhibitor, reduces the expression of oncogenes such as Myc and Bcl-2, which affects cancer growth and development. However, it has modest activity because of the narrow therapeutic index. Therefore, combination therapy is necessary to increase the anti-tumor effect. Paclitaxel, an anti-mitotic inhibitor, is used as second-line therapy for gastric cancer (GC) as a monotherapy or combination. In this study, we performed RNA sequencing of GC cells treated with iBET-151 and/or paclitaxel to identify the differentially expressed genes associated with possible mechanisms of synergistic effect. We also performed Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes pathway analyses to determine the most enriched terms and pathways of upregulated and downregulated genes. We found 460 genes in which iBET-151 and paclitaxel combination treatment changed more than single-treatment or no-treatment. Thus, additional functional studies are needed, but our results provide the first evidence of the synergistic effect between iBET-151 and paclitaxel in regulating the transcriptome of GC cells.

Antibody-Based Targeting of Interferon-Beta-1a Mutein in HER2-Positive Cancer Enhances Antitumor Effects Through Immune Responses and Direct Cell Killing

Type I interferon (IFN) has been approved as an anticancer agent to treat some malignancies. However, IFNs have a short in vivo half-life, systemic toxicity, and poor biophysical properties, which prevent it from being widely used for cancer therapy. This study aimed to construct recombinant IFN-β-1a mutein immunocytokines that comprise a human epidermal growth factor receptor 2 (HER2)-targeting antibody and IFN-β muteins with an additional glycosylation, which can overcome the limitation of the cytokine itself. Hence, the molecular design aims to 1) enhance productivity and biophysical properties by adding secondary glycosylation in IFN-β, 2) increase the therapeutic index of IFN-β therapy by preferential retention at the tumor by possessing high affinity for HER2-expressing cancer cells, and 3) improve the pharmacokinetics and, thus, the convenience of IFN-β administration. The yield of trastuzumab-IFN-β mutein was higher than that of trastuzumab-wild-type IFN-β in the mammalian cell culture system. Trastuzumab-IFN-β mutein showed similar IFN activity and HER2-targeting ability equivalent to that of IFN-β mutein and trastuzumab, respectively. Trastuzumab-IFN-β mutein directly inhibited the growth of HER2-positive gastric cancer cell lines and was more effective than trastuzumab or IFN-β mutein alone. Trastuzumab-IFN-β mutein and IFN-β mutein displayed enhanced immune cell-mediated cytotoxicity. Collectively, trastuzumab-IFN-β mutein may have indirect immune cell-mediated antitumor effects and direct cell growth inhibitory effects. Tumor-targeting effect of trastuzumab-IFN-β mutein was analyzed using in vivo fluorescence imaging. The accumulation of trastuzumab-IFN-β mutein was observed in HER2-positive tumors rather than other tissues except the liver. To evaluate the both direct tumor growth inhibition effect and indirect immune cell-mediated antitumor effect, we tested the effect of trastuzumab-IFN-β mutein in HER2-positive cancer xenograft models using nude mice or humanized mice. Trastuzumab-IFN-β mutein could significantly enhance tumor regression when compared with trastuzumab or IFN-β mutein. In addition, an increase in tumor-infiltrating lymphocytes was observed in the trastuzumab-IFN-β mutein-treated group, implying that the tumor-targeting IFN-β may have an enhanced antitumor effect through increased immune response. Therefore, targeting IFN-β with an anti-HER2 monoclonal antibody makes the immunocytokine more potent than either agent alone. These novel findings suggest that trastuzumab-IFN-β mutein merits clinical evaluation as a new candidate of anticancer therapeutics.

p16 methylation is a potential predictive marker for abemaciclib sensitivity in gastric cancer

Cell cycle control is often disrupted in gastric cancer (GC), making it an attractive therapeutic target. Abemaciclib is a specific CDK4/6 inhibitor that has been shown to improve treatment efficacy in hormone receptor-positive advanced breast cancer; however, its potential therapeutic value and predictive markers have not yet been revealed in GC. In this study, we investigated the efficacy of abemaciclib using preclinical GC models representing defined molecular subtypes from The Cancer Genome Atlas. In these 49 GC cell lines, Epstein-Barr virus (EBV) and high microsatellite instability (MSI-H)-type cell lines were p16 methylated and sensitive to abemaciclib; further, genomically stable (GS), and chromosomal instability (CIN)-type cell lines with p16 methylation and intact Rb were also found to be responsive. In addition, we found that GC patients with p16 methylation often displayed a poor prognosis. Collectively, these data provide a foundation for clinical trials to assess the therapeutic efficacy of abemaciclib in GC and suggest that p16 methylation could be used as a predictive marker to identify patients with GC who may benefit from abemaciclib-based therapies.

Gene Expression Profiling Identifies Akt as a Target for Radiosensitization in Gastric Cancer Cells

Background

Despite the important role of radiotherapy in cancer treatment, a subset of patients responds poorly to treatment majorly due to radioresistance. Particularly the role of radiotherapy has not been established in gastric cancer (GC). Herein, we aimed to identify a radiosensitivity gene signature and to discover relevant targets to enhance radiosensitivity in GC cells.

Methods

An oligonucleotide microarray (containing 22,740 probes) was performed in 12 GC cell lines prior to radiation. A clonogenic assay was performed to evaluate the survival fraction at 2 Gy (SF2) as a surrogate marker for radiosensitivity. Genes differentially expressed (fold change > 6, q-value < 0.025) were identified between radiosensitive and radioresistant cell lines, and quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) was performed for validation. Gene set and pathway analyses were performed using Ingenuity Pathway Analysis (IPA).

Results

Radiosensitive (SF2 < 0.4) and radioresistant cell lines (SF2 ≥ 0.6) exhibited a marked difference in gene expression. We identified 68 genes that are differentially expressed between radiosensitive and radioresistant cell lines. The identified genes showed interactions via AKT, HIF1A, TGFB1, and TP53, and their functions were associated with the genetic networks associated with cellular growth and proliferation, cellular movement, and cell cycle. The Akt signaling pathway exhibited the highest association with radiosensitivity. Combinatorial treatment with MK-2206, an allosteric Akt inhibitor, and radiotherapy significantly increased cell death compared with radiotherapy alone in two radioresistant cell lines (YCC-2 and YCC-16).

Conclusion

We identified a GC-specific radiosensitivity gene signature and suggest that the Akt signaling pathway could serve as a therapeutic target for GC radiosensitization.

The expression of epidermal growth factor receptor 1 and human epidermal growth factor receptor 2 based on tumor location affect survival in gastric cancer

To investigate the different expression of epidermal growth factor receptor 1 (EGFR) and human epidermal growth factor receptor 2 (HER2) in gastric cancer based on tumor locations and its impact on patients survival.Gastric cancer is heterogeneous disease, recent years have established a molecular classification and described distribution of molecular subtypes in stomach. However, the difference of EGFR and HER-2 expression among tumor location is still unknown.Between January 2010 and August 2014, 2477 consecutive patients with gastric cancer were treated in our surgery department. The tumor locations were classified into 4 groups: cardia, fundus, corpus, and antrum. Based on tumor locations, the clinicopathologic characteristics, EGFR and HER-2 expression, and follow-up data were analyzed by univariant analysis and Kaplan-Meier analysis retrospectively.There were difference of gender, age, Borrmann type, pathological type, differentiation, T-stage, tumor size, gastrectomy method, and complications among the locations. The positive rate of EGFR expression in fundus was 18.18%, which was lower than cardia (46.21%), corpus (43.62%), and antrum (48.83%) (P < .001). The 5-year survival rate in EGFR positive patients was 50.8%, which was significantly lower than EGFR negative patients (64.0%, P = .021). The positive rate of HER-2 expression in cardia was 48.15%, which was significantly higher than fundus (37.5%), corpus (35.45%), and antrum (38.54%) (P = .009), but HER-2 expression did not correlate with 5-year survive (P = .548).Our results suggest that there exist difference of EGFR and HER-2 expression based on tumor locations, and the distribution of EGFR impact on patients survival. Emphasizing the role of EGFR and HER-2 in the context of location contribute to make appropriate treatment strategy and improve prognosis of gastric cancer.

Design, Synthesis, and Biological Evaluation of Pyridineamide Derivatives Containing a 1,2,3-Triazole Fragment as Type II c-Met Inhibitors

A series of 4-(pyridin-4-yloxy)benzamide derivatives containing a 1,2,3-triazole fragment were designed, synthesized, and their inhibitory activity against A549, HeLa, and MCF-7 cancer cell lines was evaluated. Most compounds exhibited moderate to potent antitumor activity against the three cell lines. Among them, the promising compound B26 showed stronger inhibitory activity than Golvatinib, with IC₅₀ values of 3.22, 4.33, and 5.82 μM against A549, HeLa, and MCF-7 cell lines, respectively. The structure–activity relationships (SARs) demonstrated that the modification of the terminal benzene ring with a single electron-withdrawing substituent (fluorine atom) and the introduction of a pyridine amide chain with a strong hydrophilic group (morpholine) to the hinge region greatly improved the antitumor activity. Meanwhile, the optimal compound B26 showed potent biological activity in some pharmacological experiments in vitro, such as cell morphology study, dose-dependent test, kinase activity assay, and cell cycle experiment. Finally, the molecular docking simulation was performed to further explore the binding mode of compound B26 with c-Met.

Inhibiting casein kinase 2 overcomes paclitaxel resistance in gastric cancer

PURPOSE

Casein kinase (CK) 2 activation has been implicated in the proliferation of various tumor types and resistance to chemotherapy. We investigated the mechanistic basis for the association between CK2 activation and paclitaxel resistance in a gastric cancer (GC).

EXPERIMENTAL DESIGN

CK2 expression was evaluated in 59 advanced GC patients treated with paclitaxel as the second-line therapy. The efficacy of a CK2 inhibitor, CX-4945, and paclitaxel was evaluated in GC cell lines and a xenograft model.

RESULTS

Patients with high CK2 expression (29/59, 39%) showed lower disease control rates (47.7% vs. 72.3%, p = 0.017) and shorter progression-free survival (2.8 vs. 4.8 months, p = 0.009) than patients with low CK2 expression. CK2 protein expression was associated with sensitivity to paclitaxel in 49 GC cell lines. Combination therapy with CX-4945 and paclitaxel exerted synergistic antiproliferative effects and inhibited the downregulation of phosphatidylinositol 3-kinase/AKT signaling in SNU-1 cells. In the SNU-1 xenograft model, the combination treatment was significantly superior to either single agent, suppressing tumor growth without notable toxicities.

CONCLUSIONS

These results demonstrated that CK2 activation was related to paclitaxel resistance and that CX-4945 in combination with paclitaxel could be used as a potential treatment for paclitaxel resistance in GC.

Long Noncoding RNA UCA1 Regulates PRL-3 Expression by Sponging MicroRNA-495 to Promote the Progression of Gastric Cancer

Gastric cancer (GC) is among the most frequently occurring malignancies worldwide. In recent years, long noncoding RNAs (lncRNAs) have been widely studied because of their ability to regulate the cellular processes involved with tumorigenesis. The present study aims to investigate the underlying molecular mechanism by which lncRNA urothelial carcinoma-associated 1 (UCA1) influences the progression of GC. Differentially expressed lncRNA UCA1 was initially identified by microarray-based analysis, after which a high expression of UCA1 was determined in GC tissues and cells. It is important to note that UCA1 could upregulate the expression of phosphatase of regenerating liver-3 (PRL-3) by sponging miR-495. The expression of UCA1 and miR-495 was altered in human GC cells to evaluate cell activity in vitro, as well as peritoneal metastasis and tumor formation ability in vivo. Results suggested that increased expression of UCA1 promoted cell proliferation, migration, and invasion, accompanied by suppressed cell apoptosis, as well as enhanced peritoneal metastasis and tumorigenesis of GC cells. Meanwhile, the upregulated expression of miR-495 could reverse the promotive effects exerted by UCA1. Taken conjointly, UCA1, as a competing endogenous RNA (ceRNA) of miR-495, could accelerate the development of GC by upregulating PRL-3, highlighting a potentially promising basis for the targeted intervention treatment of GC.

MET as resistance factor for afatinib therapy and motility driver in gastric cancer cells

The therapeutic options for advanced gastric cancer are still limited. Several drugs targeting the epidermal growth factor receptor family have been developed. So far, the HER2 antibody trastuzumab is the only drug targeting the HER-family that is available to gastric cancer patients. The pan-HER inhibitor afatinib is currently investigated in clinical trials and shows promising results in cell culture experiments and patient-derived xenograft (PDX) models. However, some cell lines do not respond to afatinib treatment. The determination of resistance factors in these cell lines can help to find the best treatment option for gastric cancer patients. In this study, we analyzed the role of MET as a resistance factor for afatinib therapy in a gastric cancer cell line. MET expression in afatinib-resistant MET-amplified Hs746T cells was reduced by means of siRNA transfection. The effects of MET knockdown on signal transduction, cell proliferation and motility were examined. In addition to the manual assessment of cell motility, a computational motility analysis involving parameters such as (approximate) average speed, displacement entropy or radial effectiveness was realized. Moreover, the impact of afatinib was compared between MET knockdown cells and control cells. MET knockdown in Hs746T cells resulted in impaired signal transduction and reduced cell proliferation and motility. Moreover, the afatinib resistance of Hs746T cells was reversed after MET knockdown. Therefore, the amplification of MET is confirmed as a resistance factor in gastric cancer cells. Whether MET is a useful resistance marker for afatinib therapy or other HER-targeting drugs in patients should be investigated in clinical trials.