New advances in targeted gastric cancer treatment

The composition and variation of the BCR CDR3s in gastric cancer

Gastric cancer (GC) is the fourth most common type of cancer and the second most common cause of cancer-associated mortality worldwide. B cell-associated autoantibodies against tumor-associated antigens are attractive biomarkers for the development of noninvasive serological tests for the early detection of cancer. This is due to their specificity and stability in the sera. In the present study multiplex polymerase chain reaction and Illumina high-throughput sequencing (HTS) was used to study the composition and variation of the B cell receptor (BCR) complimentary-determining region 3 (CDR3) in GC. The peripheral blood, cancer tissues and peri-cancer tissues were included from 7 patients with GC. On average there was a total of 403,959 CDR3 sequences, with 72,367 unique CDR3 nt sequences and 61,709 unique CDR3 aa sequences per sample identified, which are critical for further understanding the BCR repertoire in GC. The details of GC CDR3s may accelerate the screening process for possible new autoantigens and may provide additional information necessary for generating effective B cell targeted diagnosis and therapeutic strategies.

Phase II Study to Evaluate the Efficacy and Safety of Rilotumumab and Bevacizumab in Subjects with Recurrent Malignant Glioma

Lessons Learned.

Due to evolving imaging criteria in brain tumors and variation in magnetic resonance imaging evaluation, it is not ideal to use response rate as a primary objective. Future studies involving antiangiogenic agents should use overall survival.

Disease‐expected toxicities should be considered when defining the clinical significance of an adverse event. For example, vascular thromboembolic events are common in brain tumor patients and should not be attributed to the study drug in the safety analysis.

Background.

Recurrent malignant glioma (rMG) prognosis is poor, with a median patient survival of 3–11 months with bevacizumab (BEV)‐containing regimens. BEV in rMG has 6‐month progression free survival (PFS‐6) of ∼40% and an objective response rate of 21.2%. BEV‐containing regimens improve PFS‐6 to 42.6%–50.3%, indicating that BEV combination therapies may be superior to single agent. Rilotumumab, a hepatocyte growth factor (HGF) antibody, inhibits angiogenesis and expression of angiogenic autocrine factors (e.g., vascular endothelial growth factor [VEGF]) by c‐Met inhibition. Combination of rilotumumab with BEV to block vascular invasion and tumor proliferation may synergistically inhibit tumor growth.

Methods.

Thirty‐six BEV‐naïve rMG subjects received rilotumumab (20 mg/kg and BEV (10 mg/kg) every 2 weeks. Endpoints included objective response rate (using Response Assessment in Neuro‐Oncology [RANO] criteria), PFS‐6, overall survival (OS), and toxicity.

Results.

Median patient follow‐up was 65.0 months. Objective response rate was 27.8% (95% confidence interval [CI]: 15.7%–44.1%). Median OS was 11.2 months (95% CI: 7–17.5). PFS‐6 was 41.7% (95% CI: 25.6%–57.0%). Most frequent treatment‐related grade ≤2 events included weight gain, fatigue, allergic rhinitis, and voice alteration; grade ≥3 events included venous thromboembolism (four patients), including one death from pulmonary embolism.

Conclusion.

Rilotumumab with BEV did not significantly improve objective response compared with BEV alone, and toxicity may preclude the use of rilotumumab in combination BEV regimens.

A novel microRNA signature predicts survival in stomach adenocarcinoma

Recent microRNA (miRNA) expression profiling studies suggest the clinical use of miRNAs as potential prognostic biomarkers in various malignancies. In this study, aiming to identify microRNAs with prognostic value for overall survival (OS) in stomach adenocarcinoma (STAD) patients, we analyzed the miRNA expression profiles and the associated clinical characteristics in 380 STAD samples from The Cancer Genome Atlas (TCGA) dataset. An eight-miRNA signature for predicting OS in STAD patients was identified and self-validated by survival analysis and semi-supervised principal components method. We developed a linear prognostic model composed of these miRNAs to divide patients into high- and low-risk groups according to the calculated prognostic scores. Kaplan-Meier analysis demonstrated that patients in the high-risk group had worse OS compared with patients in the low-risk group. Notably, this miRNA prognostic model showed prognostic significance to the STAD patients in early stages and the chemo-resistant patients, who would potentially benefit from additional medical interventions. Finally, this eight-miRNA signature is an independent prognostic biomarker and demonstrates a good predictive performance for 5-year survival. Thus, this signature may serve as a novel biomarker for predicting survival as well as chemotherapy response in STAD patients.

Long non-coding RNA PTENP1 functions as a ceRNA to modulate PTEN level by decoying miR-106b and miR-93 in gastric cancer. Oncotarget. 2017;8:26079-26089. [PMID: 28212532 PMCID: PMC5432239 DOI: 10.18632/oncotarget.15317]

Recent studies have shown that competing endogenous RNAs (ceRNAs) play an important role in the regulation of gene expression, and participate in a wide range of biological processes, including carcinogenesis. Long non-coding RNA PTENP1, the pseudogene of PTEN tumor suppressor, has been reported to exert its tumor suppressive function via modulation of PTEN expression in many malignancies. However, whether a PTENP1∼miRNA∼PTEN ceRNA network exists and how it functions in gastric cancer (GC) remains elusive. In order to identify and characterize the PTENP1∼miRNA∼PTEN ceRNA network in GC, we first determined PTENP1 levels in clinical GC samples and found that PTENP1 and PTEN were concurrently downregulated in these samples. We further demonstrated that PTENP1 could act as a ceRNA to sponge miR-106b and miR-93 from targeting PTEN for downregulation using a novel ceRNA in vitro gradient assay. Thus, we revealed a tumor suppressive role of PTENP1 as ceRNA in GC and pinpointed the specific miRNAs decoyed by PTENP1, highlighting the emerging roles of ceRNAs in the biological regulation of GC cells and their possible clinical significance.

Identification of significant biomarkers and pathways associated with gastric carcinogenesis by whole genome-wide expression profiling analysis

The incidence of gastric cancer (GC) is extremely high in East Asia. GC is also one of the most common and lethal forms of cancer from a global perspective. However, to date, we have not been able to determine one or several genes as biomarkers in the diagnosis of GC and have also been unable to identify the genes which are important in the therapy of GC. In this study, we analyzed all genome-wide expression profiling arrays uploaded onto the Gene Expression Omnibus (GEO) database to filtrate the differentially expressed genes (DEGs) between normal stomach tissues and GC tissues. GSE13911, GSE19826 and GSE79973 were based on the GPL570 platform, and GSE29272 was based on the GPL96 platform. We screened out the DEGs from the two platforms and by selecting the intersection of these two platforms, we identified the common DEGs in the sequencing data from different laboratories. Finally, we obtained 3 upregulated and 34 downregulated DEGs in GC from 384 samples. As the number of downregulated DEGs was greater than that of the upregulated DEGs, functional analysis and pathway enrichment analysis were performed on the downregulated DEGs. Through our analysis, we identified the most significant genes associated with GC, such as secreted phosphoprotein 1 (SPP1), sulfatase 1 (SULF1), thrombospondin 2 (THBS2), ATPase H+/K+ transporting beta subunit (ATP4B), gastric intrinsic factor (GIF) and gastrokine 1 (GKN1). The prognostic power of these genes was corroborated in the Oncomine database and by Kaplan-Meier plotter (KM-plotter) analysis. Moreover, gastric acid secretion, collecting duct acid secretion, nitrogen metabolism and drug metabolism were significantly related to GC. Thus, these genes and pathways may be potential targets for improving the diagnosis and clinical effects in patients with GC.

vacA s1m1 genotype and cagA EPIYA-ABC pattern are predominant among Helicobacter pylori strains isolated from Mexican patients with chronic gastritis

Purpose

Virulent genotypes of Helicobacter pylori vacA s1m1/cagA⁺/babA2⁺ have been associated with severe gastric diseases. VacA, CagA and BabA are polymorphic proteins, and their association with the disease is allele-dependent. The aims of this work were: (i) to determine the prevalence of H. pylori by type of chronic gastritis; (ii) to describe the frequency of cagA, babA2 and vacA genotypes in strains from patients with different types of chronic gastritis; (iii) to characterize the variable region of cagA alleles.

Methodology

A total of 164 patients with chronic gastritis were studied. Altogether, 50 H. pylori strains were isolated, and the status of cagA, babA2 and vacA genotypes was examined by PCR. cagA EPIYA segment identification was performed using PCR and sequencing of cagA fragments of six randomly selected strains.

Results/Key findings

The overall prevalence of H. pylori was 30.5 %. Eighty percent of the isolated strains were vacA s1m1, and the cagA and babA2 genes were detected in 74 and 32 % of the strains, respectively. The most frequent genotypes were vacA s1m1/cagA⁺/babA2^- and vacA s1m1/cagA⁺/babA2⁺, with 40 % (20/50) and 28 % (14/50), respectively. In cagA⁺, the most frequent EPIYA motif was -ABC (78.4 %), and EPIYA-ABCC and -ABCCC motifs were found in 10.8 % of the strains. A modified EPIYT-B motif was found in 66.6 % of the sequenced strains.

Conclusion

H. pylori strains carrying vacA s1m1, cagA⁺ and babA2^- genotypes were the most prevalent in patients with chronic gastritis from the south of Mexico. In the cagA⁺ strains, the EPIYA-ABC motif was the most common.

Clinical value of peripheral blood microRNA detection in evaluation of SOX regimen as neoadjuvant chemotherapy for gastric cancer

BACKGROUND

Neoadjuvant chemotherapy has been widely applied in treating advanced gastric cancer (GC). However, little research has been conducted on evaluating the effect of neoadjuvant chemotherapy. Purpose of this study was to evaluate the effect of SOX regimen as neoadjuvant chemotherapy by detecting some microRNAs.

METHODS

Total 120 GC patients who had received neoadjuvant chemotherapy (SOX regimen) were recruited with 100 healthy participants as control contemporarily. Age and gender have no significant difference in both groups (P > .05). The effect of chemotherapy was evaluated by the results of CT scan and surgery. Also, adverse effects of chemotherapy were documented. Peripheral blood of GC patients was collected twice: one day before chemotherapy and surgery, respectively, whereas healthy controls' peripheral blood was collected once. Quantitative real-time PCR (qPCR) was utilized to detect expression of miR-145, miR-185, miR-381, and miR-195 of peripheral blood in both groups.

RESULTS

One hundred and twenty patients with advanced GC completed a total of 386 cycles of neoadjuvant chemotherapy with effective rate at 84.17% (101 of 120). Expression of miR-145, miR-185, and miR-381 of patients with GC was lower than that in the control group before chemotherapy commence (all P < .05), while the expressions of miR-145 and miR-185 elevated noticeably in CG patients after neoadjuvant chemotherapy (P < .05). The differences in the expression of miR-145 and miR-185 in advanced GC patients with different chemotherapy outcomes were detected.

CONCLUSION

Patients with GC at advanced stages had aberrant miRs expressions. Detection of miR-145 and miR-185 expression may assist to predict effectiveness and adverse effects of SOX regimen as neoadjuvant chemotherapy.

Long noncoding RNA SNHG20 promotes gastric cancer progression by inhibiting p21 expression and regulating the GSK-3β/ β-catenin signaling pathway

Recent studies have indicated that long non-coding RNAs (lncRNAs) play important regulatory roles in tumor development and progression. However, the contribution of small nucleolar RNA host gene 20 (SNHG20) to gastric cancer development remains largely unknown. The aim of the study is to investigate the functional significance of SNHG20 involved in gastric cancer (GC) progression. In the study, our results demonstrated that the expression levels of SNHG20 were remarkably up-regulated in GC cells. Functionally, SNHG20 promoted the GC MKN45 and BGC-823 cells proliferation and invasion. Furthermore, knockdown of SNHG20 significantly inhibited the epithelial-mesenchymal transition (EMT) in MKN45 and BGC-823 cells, whereas, the overexpression of SNHG20 had the promoting effects. Moreover, we found that overexpression of SNHG20 in MKN45 and BGC-823 cells significantly inhibited the expression of E-cadherin and p21 via binding to EZH2 and regulated the GSK-3β/β-catenin signaling pathway. Thus, the results showed that SNHG20 acted as an oncogene in GC and targeting SNHG20 may serve as a therapeutic target for GC.

Combined aspirin and apatinib treatment suppresses gastric cancer cell proliferation

Gastric cancer (GC), one of the types of tumor most prone to malignancy, is characterized by high lethality. Numerous molecular mediators of GC have been identified, including transcription factors, signaling molecules and non-coding RNAs. Recently, inhibition of angiogenesis has emerged as a potential strategy for GC therapy. In the present study, the levels of vascular endothelial growth factor (VEGF), peroxisome proliferator-activated receptor-α (PPARα) and miR-21 in GC patients and individuals without cancer, and the correlation between VEGF and miR-21, and PPARα and miR-21 expression were analyzed. In addition, the GC MKN45 cell line was treated with apatinib (a tyrosine kinase inhibitor) and aspirin (an activator of the transcription factor, PPARα) to investigate the effects of these compounds on tumorigenesis. Furthermore, the present study attempted to elucidate the molecular mechanisms of alteration of GC tumorigenesis by aspirin and apatinib. The results of the current study demonstrated that there was a higher expression of VEGF and miR-21 in GC tissues compared with that in morphologically adjacent normal tissues whereas PPARα expression was decreased. These results were confirmed in vitro, as treatment of MKN45 cells with VEGF resulted in a significant increase in miR-21 expression and a significant reduction in PPARα protein expression. Furthermore, the inhibitory effects of VEGF on PPARα mRNA and protein expression were demonstrated to be mediated by miR-21. Suppression of PPARα protein expression attenuated the inhibitory effects of miR-21 on the level of PPARα mRNA, thereby enhancing tumorigenesis in gastric cancer. Treatment of MKN45 cells with aspirin reduced the levels of phosphorylated AKT by activating PPARα, whereas treatment with apatinib inhibited the phosphorylation of vascular endothelial growth factor receptor 2 and phosphoinositide-3 kinase in MKN45 cells. Finally, treatment of MKN45 cells with apatinib and aspirin suppressed tumorigenesis by inhibiting cell proliferation, migration, invasion and colony formation. Taken together, the results of the present study indicate that treatment with a combination of aspirin and apatinib may be a potential therapeutic strategy for GC treatment.

Morusin inhibits cell proliferation and tumor growth by down-regulating c-Myc in human gastric cancer

Morusin is a pure extract from the root bark of Morus australis (Moraceae). In recent years, morusin has been reported to exhibit anti-tumor biological activity in some types of human cancers through different mechanisms. Here, we attempted to investigate the inhibitory effect and mechanism of morusin on gastric cancer. Morusin markedly inhibited gastric cancer cell proliferation by down-regulating CDKs and Cyclins, such as CDK2, CDK4, Cyclin D1 and Cyclin E1. Additionally, morusin suppressed tumor growth in vitro and in vivo. Up-regulation of CDKs and Cyclins in gastric cancer cells was induced by c-Myc binding at the E-Box regions of CDKs and the Cyclin promoter. In addition, compared with the control group, the morusin-treated group showed reduced expression of c-Myc and c-Myc protein binding at the E-Box regions. Based on these results, we overexpressed c-Myc in gastric cancer cells and found that overexpressing c-Myc rescued morusin-induced inhibition of cell proliferation and tumor growth. These results suggest that morusin inhibits cell proliferation and tumor growth by down-regulating c-Myc in human gastric cancer.

Clinical value of miR-425-5p detection and its association with cell proliferation and apoptosis of gastric cancer

Researches have shown that miR-425-5p expression altered in lung, esophageal, and glial cancer. Similarly, in our previous study, we found miR-425-5p expression was up-regulated in GC cells and could promote gastric cancer (GC) cell invasion and metastasis. However, the functional mechanism and the prognostic significance of miR-425-5p in GC remain unclear. Therefore, the present study examined miR-425-5p expression in GC tissues and also evaluated miR-425-5p of the therapeutic and prognostic value. Moreover, with interference of miR-425-5p expression in cell lines, we investigated the molecular mechanism of miR-425-5p and the expression level was higher in GC tissues comparing with that in gastric tumor-adjacent mucosa. These results suggested that miR-425-5p over-expression may be associated with depth of invasion and TNM stages and can be a prognostic marker of poor outcome. After inhibition of miR-425-5p expression in MKN45 cells, the cell activity was weakened. The number of G0/G1 cells increased while G2/M and S cells decreased, and the cell apoptotic rates elevated (P<0.05). Some proliferation and apoptosis related genes were altered (P<0.05). Consequently, miR-425-5p can be considered as a marker of poor prognosis and it is probably involved in GC cell proliferation and apoptosis by regulating some of the genes which participate these processes.

MiR-29 modulates multidrug resistance of gastric cancer cells by targeting Mcl-1

AIM

To investigate the differential expression of miR-29 in SGC7901/vincristine (VCR), SGC7901/adriamycin (ADR) and SGC7901 gastric cancer cell lines, and to explore its role in multidrug resistance of gastric cancer cells and the possible mechanism involved.

METHODS

qRT-PCR was used to detect the expression of miR-29 in different gastric cancer cell lines. After up- or down-regulation of miR-29 expression, MTT assay was applied to detect the changes in drug sensitivity (IC₅₀) of different gastric cancer cell lines. Apoptosis and cell cycle arrest were analyzed by flow cytometry. Western blot analysis and luciferase assay were performed to investigate the possible mechanism involved.

RESULTS

The expression levels of the miR-29 family members (miR-29a/b/c) in SGC7901/VCR and SGC7901/ADR cell lines were significantly lower than those in parental SGC7901 cells (P < 0.05). MTT assay showed that down-regulation of miR-29 led to a significant increase in the drug sensitivity (IC₅₀) of SGC7901 cells, while up-regulation of miR-29 induced a significant decrease in the drug sensitivity (IC₅₀) of SGC7901/VCR and SGC7901/ADR cells (P < 0.05). Flow cytometry analysis indicated that altered miR-29 expression caused significant changes in 5-fluorouridine induced apoptosis (P < 0.05). Western blot analysis and luciferase assay demonstrated that in gastric cancer cells myeloid cell leukemia-1 (Mcl-1) is the direct functional target of miR-29.

CONCLUSION

MiR-29 modulates multidrug resistance of gastric cancer cells by directly targeting the expression of anti-apoptotic Mcl-1.