Hypermethylated Epidermal growth factor receptor (EGFR) promoter is associated with gastric cancer

Hypoxia Alters the Response to Anti-EGFR Therapy by Regulating EGFR Expression and Downstream Signaling in a DNA Methylation-Specific and HIF-Dependent Manner

Intratumoral hypoxia occurs in 90% of solid tumors and is associated with a poor prognosis for patients. Cancer cells respond to hypoxic microenvironments by activating the transcription factors, hypoxia-inducible factor 1 (HIF1) and HIF2. Here, we studied the unique gene expression patterns of 31 different breast cancer cell lines exposed to hypoxic conditions. The EGFR, a member of the ErbB (avian erythroblastosis oncogene B) family of receptors that play a role in cell proliferation, invasion, metastasis, and apoptosis, was induced in seven of the 31 breast cancer cell lines by hypoxia. A functional hypoxia response element (HRE) was identified, which is activated upon HIF1 binding to intron 18 of the EGFR gene in cell lines in which EGFR was induced by hypoxia. CpG methylation of the EGFR HRE prevented induction under hypoxic conditions. The HRE of EGFR was methylated in normal breast tissue and some breast cancer cell lines, and could be reversed by treatment with DNA methyltransferase inhibitors. Induction of EGFR under hypoxia led to an increase in AKT, ERK, and Rb phosphorylation as well as increased levels of cyclin D1, A, B1, and E2F, and repression of p21 in an HIF1α-dependent manner, leading to cell proliferation and migration. Also, increased EGFR expression sensitized cells to EGFR inhibitors. Collectively, our data suggest that patients with hypoxic breast tumors and hypomethylated EGFR status may benefit from EGFR inhibitors currently used in the clinic. SIGNIFICANCE: Hypoxia sensitizes breast cancer cells to EGFR inhibitors in an HIF1α- and a methylation-specific manner, suggesting patients with hypoxic tumors may benefit from EGFR inhibitors already available in the clinic. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/22/4998/F1.large.jpg.

Zinc as a plausible epigenetic modulator of glioblastoma multiforme

Glioblastoma Multiforme (GBM) is an aggressive brain tumor (WHO grade 4 astrocytoma) with unknown causes and is associated with a reduced life expectancy. The available treatment options namely radiotherapy, surgery and chemotherapy have failed to improve life expectancy. Out of the various therapeutic approaches, epigenetic therapy is one of the most studied. Epigenetic therapy is involved in the effective treatment of GBM by inhibiting DNA methyltransferase, histone deacetylation and non-coding RNA. It also promotes the expression of the tumor suppressor gene and is involved in the suppression of the oncogene. Various targets are being studied to implement proper epigenetic regulation to control GBM effectively. Zinc is one of the micronutrients which is considered to maintain epigenetic regulation by promoting the proper DNA folding, protecting genetic material from the oxidative damage and controlling the enzyme activation involved in the epigenetic regulation. Here, we are discussing the importance of zinc in regulating the epigenetic modifications and assessing its role in glioblastoma research. The discussion also highlights the importance of artificial intelligence using epigenetics for envisaging the glioma progression, diagnosis and its management.

Long non-coding RNAs in gastric cancer: New emerging biological functions and therapeutic implications

Gastric cancer (GC) is currently the fourth most common malignancy and the third leading cause of cancer-related deaths worldwide. Long non-coding RNAs (lncRNAs), transcriptional products with more than 200 nucleotides, are not as well-characterized as protein-coding RNAs. Accumulating evidence has recently revealed that maladjustments of diverse lncRNAs may play key roles in multiple genetic and epigenetic phenomena in GC, affecting all aspects of cellular homeostasis, such as proliferation, migration, and stemness. However, the full extent of their functionality remains to be clarified. Considering the lack of viable biomarkers and therapeutic targets, future research should be focused on unravelling the intricate relationships between lncRNAs and GC that can be translated from bench to clinic. Here, we summarized the state-of-the-art advances in lncRNAs and their biological functions in GC, and we further discuss their potential diagnostic and therapeutic roles. We aim to shed light on the interrelationships between lncRNAs and GC with respect to their potential therapeutic applications. With better understanding of these relationships, the biological functions of lncRNAs in GC development will be exploitable, and promising new strategies developed for the prevention and treatment of GC.

Bone morphogenetic proteins mediate crosstalk between cancer cells and the tumour microenvironment at primary tumours and metastases (Review)

Bone morphogenetic proteins (BMP) are pluripotent molecules, co‑ordinating cellular functions from early embryonic and postnatal development to tissue repair, regeneration and homeostasis. They are also involved in tumourigenesis, disease progression and the metastasis of various solid tumours. Emerging evidence has indicated that BMPs are able to promote disease progression and metastasis by orchestrating communication between cancer cells and the surrounding microenvironment. The interactions occur between BMPs and epidermal growth factor receptor, hepatocyte growth factor, fibroblast growth factor, vascular endothelial growth factor and extracellular matrix components. Overall, these interactions co‑ordinate the cellular functions of tumour cells and other types of cell in the tumour to promote the growth of the primary tumour, local invasion, angiogenesis and metastasis, and the establishment and survival of cancer cells in the metastatic niche. Therefore, the present study aimed to provide an informative summary of the involvement of BMPs in the tumour microenvironment.

Tyrosine Kinases in Helicobacter pylori Infections and Gastric Cancer

Helicobacter pylori (H. pylori) has been identified as a leading cause of gastric cancer, which is one of the most frequent and malignant types of tumor. It is characterized by its rapid progression, distant metastases, and resistance to conventional chemotherapy. A number of receptor tyrosine kinases and non-receptor tyrosine kinases have been implicated in H. pylori-mediated pathogenesis and tumorigenesis. In this review, recent findings of deregulated EGFR, c-Met, JAK, FAK, Src, and c-Abl and their functions in H. pylori pathogenesis are summarized.

NMR-based metabolomics Reveals Alterations of Electro-acupuncture Stimulations on Chronic Atrophic Gastritis Rats

Chronic atrophic gastritis (CAG) is a common gastrointestinal disease which has been considered as precancerous lesions of gastric carcinoma. Previously, electro-acupuncture stimulation has been shown to be effective in ameliorating symptoms of CAG. However the underlying mechanism of this beneficial treatment is yet to be established. In the present study, an integrated histopathological examination along with molecular biological assay, as well as ¹H NMR analysis of multiple biological samples (urine, serum, stomach, cortex and medulla) were employed to systematically assess the pathology of CAG and therapeutic effect of electro-acupuncture stimulation at Sibai (ST 2), Liangmen (ST 21), and Zusanli (ST 36) acupoints located in the stomach meridian using a rat model of CAG. The current results showed that CAG caused comprehensive metabolic alterations including the TCA cycle, glycolysis, membrane metabolism and catabolism, gut microbiota-related metabolism. On the other hand, electro-acupuncture treatment was found able to normalize a number of CAG-induced metabolomics changes by alleviating membrane catabolism, restoring function of neurotransmitter in brain and partially reverse the CAG-induced perturbation in gut microbiota metabolism. These findings provided new insights into the biochemistry of CAG and mechanism of the therapeutic effect of electro-acupuncture stimulations.

Dynamic tracing for epidermal growth factor receptor mutations in urinary circulating DNA in gastric cancer patients

The mutations of epidermal growth factor receptor are detected in gastric cancer, indicating its suitability as a target for receptor tyrosine kinase inhibitors, as well as a marker for clinical outcome of chemotherapeutic treatments. However, extraction of quality tumor tissue for molecular processes remains challenging. Here, we aimed to examine the clinical relevance of urinary cell-free DNA as an alternative tumor material source used specifically for monitoring epidermal growth factor receptor mutations. Therefore, 120 gastric cancer patients with epidermal growth factor receptor mutations and 100 healthy controls were recruited for the study. The gastric patients also received epidermal growth factor receptor inhibitor treatment for a serial monitoring study. Paired primary tumor specimens were obtained with blood and urine samples, which were taken at a 1-month interval for a duration of 12 months. We found that urinary cell-free DNA yielded a close agreement of 92% on epidermal growth factor receptor mutation status when compared to primary tissue at baseline, and of 99% epidermal growth factor receptor mutation status when compared to plasma samples at different time points. Thus, our data suggest that urinary cell-free DNA may be a reliable source for screening and monitoring epidermal growth factor receptor mutations in the primary gastric cancer.

Methylation analysis of plasma cell-free DNA for breast cancer early detection using bisulfite next-generation sequencing

Circulating cell-free DNA (cfDNA) has been considered as a potential biomarker for non-invasive cancer detection. To evaluate the methylation levels of six candidate genes (EGFR, GREM1, PDGFRB, PPM1E, SOX17, and WRN) in plasma cfDNA as biomarkers for breast cancer early detection, quantitative analysis of the promoter methylation of these genes from 86 breast cancer patients and 67 healthy controls was performed by using microfluidic-PCR-based target enrichment and next-generation bisulfite sequencing technology. The predictive performance of different logistic models based on methylation status of candidate genes was investigated by means of the area under the ROC curve (AUC) and odds ratio (OR) analysis. Results revealed that EGFR, PPM1E, and 8 gene-specific CpG sites showed significantly hypermethylation in cancer patients' plasma and significantly associated with breast cancer (OR ranging from 2.51 to 9.88). The AUC values for these biomarkers were ranging from 0.66 to 0.75. Combinations of multiple hypermethylated genes or CpG sites substantially improved the predictive performance for breast cancer detection. Our study demonstrated the feasibility of quantitative measurement of candidate gene methylation in cfDNA by using microfluidic-PCR-based target enrichment and bisulfite next-generation sequencing, which is worthy of further validation and potentially benefits a broad range of applications in clinical oncology practice. Quantitative analysis of methylation pattern of plasma cfDNA by next-generation sequencing might be a valuable non-invasive tool for early detection of breast cancer.

Effects of combining erlotinib and RNA-interfered downregulation of focal adhesion kinase expression on gastric cancer

Objective

To investigate the synergistic effects of combining erlotinib and RNA-interference downregulation of focal adhesion kinase (FAK) expression on the proliferation, apoptosis, invasion and migration of the human gastric adenocarcinoma cell line AGS.

Methods

Cells were divided into five experimental groups: Group A, nontransfected control; Group B, transfected with empty vector; Group C, transfected with FAK-shRNA; Group D, erlotinib treatment; Group E, combination erlotinib treatment and transfected with FAK-shRNA. FAK protein levels were confirmed via Western blotting. Cell proliferation (CCK-8 assay, apoptosis (flow cytometry), cell invasion (transwell assay) and migration (scratch assay) were evaluated.

Results

RNA interference significantly decreased FAK protein levels. Cell proliferation, invasion and migration were significantly lower in Groups C, D and E compared with Group A, and significantly lower in Group E than in Groups C and D.

Conclusions

RNA interference effectively silences FAK expression and inhibits malignant cell proliferation and invasion in gastric cancer cells. The effect of FAK inhibition is increased by co-treatment with erlotinib.

Tumor-associated macrophages of the M2 phenotype contribute to progression in gastric cancer with peritoneal dissemination

BACKGROUND

Tumor-associated macrophages (TAMs) of the M2 phenotype are known to promote tumor proliferation and to be associated with a poor prognosis in numerous cancers. Here, we investigated whether M2 macrophages participate in the development of peritoneal dissemination in gastric cancer.

METHODS

The characteristics of peritoneal macrophages in gastric cancer patients with or without peritoneal dissemination were examined by flow cytometry and the real-time quantitative polymerase chain reaction. The effects of M2 macrophages on phenotypic changes of the gastric cancer cell line MKN45 were assessed with a direct or indirect co-culture system in vitro and an in vivo mouse xenograft model.

RESULTS

The number of peritoneal macrophages with the M2 phenotype (CD68(+)CD163(+) or CD68(+)CD204(+)) was significantly higher in gastric cancer patients with peritoneal dissemination than in those without peritoneal dissemination. Higher expression of the M2-related messenger RNAs (IL-10, vascular endothelial growth factor A, vascular endothelial growth factor C, matrix metalloproteinase 1, and amphiregulin) and lower expression of M1-related messenger RNAs (TNF-α, CD80, CD86, and IL-12p40) were also confirmed in the TAMs. Macrophage co-culture with gastric cancer cells converted M1 phenotype into M2 phenotype. Moreover, the coexistence of MKN45 cells with M2 macrophages resulted in cancer cell proliferation and an acceleration of tumor growth in the xenograft model.

CONCLUSIONS

Intraperitoneal TAMs in gastric cancer patients with peritoneal dissemination were polarized to the M2 phenotype, and could contribute to tumor proliferation and progression. Therefore, intraperitoneal TAMs are expected to be a promising target in the treatment of peritoneal dissemination in gastric cancer.

Linc00152 promotes proliferation in gastric cancer through the EGFR-dependent pathway

Background

Linc00152 has been identified highly associated with the tumorigenesis and development of gastric cancer, however, the detailed mechanism of Linc00152 involved still remains unclear.

Methods

RT-PCR and western blot were used to detect the expression of Linc00152 and EGFR. The CCK8 and EDU assay was employed to measure cell proliferation while xenotransplantation technology was applied in BALB/C nude mice. The interaction between lncRNA and target protein was investigated by RNA pull-down and RNA immunoprecipitation assay.

Results

In this study, we first confirmed the upregulation of cytoplasmic expressed Linc00152 in 72 pair tissues of gastric patients. A suppression of cell proliferation and tumor growth was obtained in MGC803 and HGC-27 cells treated with Linc00152 shRNA. RNA pull-down and RIP assay revealed that Linc00152 could directly bind with EGFR which caused an activation of PI3K/AKT signaling.

Conclusion

We first found that Linc00152 could promote tumor growth through EGFR-mediated PI3K/AKT pathway which may serve as potential targets for therapy in the future.