EGFR as a Prognostic Marker for Gastric Cancer

Progress in research of tumor biomarkers and molecular imaging probes for gastric cancer

Gastric cancer is a malignant tumor still associated with high morbidity and mortality worldwide. Its onset is relatively insidious, and when detected, it is already at an advanced stage, lacks effective individualized treatments, and has a poor prognosis. If gastric cancer can be diagnosed at an early stage, the survival rate of patients can be greatly improved. However, traditional imaging modalities lack specificity and sensitivity. In recent years, molecular imaging technology is booming, which can non-invasively and dynamically monitor gastric cancer at the cellular and molecular levels, and provide more reference information for clinical selection of treatment options and assessment of efficacy and prognosis. This article reviews the biomarkers of gastric cancer and molecular probes in various imaging modalities.

Dendrobium as a new natural source of bioactive for the prevention and treatment of digestive tract diseases: A comprehensive review with future perspectives

BACKGROUND

The incidence of diseases related to the digestive tract is on the rise, with many types of complex etiologies. Dendrobium nobile Lindl. is a famous Traditional Chinese Medicine (TCM) rich in many bioactives proven to be beneficial in several health diseases related to inflammation and oxidative stress.

PURPOSE

At present, despite the availability of various therapeutic clinical drugs used for the treatment of digestive tract diseases, resistance emergence and existence of several side effects warrant for the developing of novel drugs for improved effects on digestive tract diseases.

METHODS

"Orchidaceae", "Dendrobium", "inflammation", "digestive tract", and "polysaccharide" were used as search terms to screen the literature. The therapeutic use of Dendrobium related to digestive tract diseases relative to known polysaccharides and other bioactive compounds were derived from online databases, including Web of Science, PubMed, Elsevier, Science Direct, and China National Knowledge Infrastructure, as well as relevant information on the known pharmacological actions of the listed phytochemicals.

RESULTS

To better capitalize upon Dendrobium for preventing and treating diseases related to digestive tract, this review summarizes bioactives in Dendrobium reported of potential in digestive tract diseases management and their underlying action mechanisms. Studies revealed that Dendrobium encompasses diverse classes including polysaccharides, phenolics, alkaloids, bibenzyls, coumarins, phenanthrene and steroids, with polysaccharide as the major class. Dendrobium exerts various health effects on a variety of disease related to the digestive tract. Action mechanisms involve antioxidant, anti-inflammatory, anti-apoptotic, antioxidant, anticancer, alongside the regulation of some key signaling pathways.

CONCLUSION

Overall, Dendrobium appears as a promising TCM source of bioactives that has the potential to be further developed into nutraceuticals for digestive tract diseases compared to current drug treatments. This review highlights for Dendrobium potential effects with future perspectives for needed future research to maximize the use of bioactive compounds from Dendrobium for digestive tract disease treatment. A compile of Dendrobium bioactives is also presented alongside methods for their extraction and enrichment for potential incorporation in nutraceuticals.

Expression of HER2/c-erbB-2, EGFR Protein in Gastric Carcinoma and its Clinical Significance

Objective

To investigate the HER2/c-erbB-2, epidermal growth factor receptor (EGFR) protein expression in gastric cancer and association with patients’ clinical pathology characteristics and prognosis.

Methods

HER2/c-erbB-2 and EGFR protein expression was examined by immunohistochemical assay in gastric cancer tissue and corresponding paired normal gastric tissue of 67 patients of gastric carcinoma. The HER2/c-erbB-2, EGFR protein positive expression rate in cancer tissue and normal gastric tissue were compared. The correlation between HER2/c-erbB-2, EGFR protein positive expression and patients’ clinical pathology characteristics and survival was evaluated.

Results

The positive expression rate of HER2/c-erbB-2 in the cancer and paired normal gastric tissues were 32.8% (22/67) and 4.5% (3/67), respectively with statistical difference (p<0.05). And the positive expression rate of EGFR in cancer and paired normal gastric tissues were 41.8% (28/67) and 5.9 (4/67), respectively, with statistical difference (p<0.05). HER2/c-erbB-2 positive expression in cancer tissue was significant correlated with the pathology grading (p<0.05), tumor invasion depth (p<0.05) and local regional lymph node metastasis (p<0.05); EGFR positive expression in cancer tissue was significant correlated with the tumor invasion depth (p<0.05) and local regional lymph node metastasis (p<0.05). The median survival time was 13.14 and 23.6 months respectively for HER2/c-erbB-2 positive and negative expression groups respectively with statistical difference ( HR=2.26, 9%CI:1.06-4.80, p<0.05). However, the median survival time was 15.47 and 22.87 months for EGFR positive and negative expression groups respectively, without statistical difference (HR=1.78, 9%CI:0.96-3.29, p>0.05).

Conclusion

Positive expression of HER2/c-erbB-2 and EGFR proteins in cancer tissue was significant higher than normal gastric tissue and have significant correlation with prognosis.

Regulatory network analysis of high expressed long non-coding RNA LINC00941 in gastric cancer

Accumulating evidence suggests that the aberrant expression of long non-coding RNAs is closely related to the carcinogenesis and progression of gastric cancer (GC), which is a type of prevalent tumor with a high incidence and mortality rate. However, it is still a challenge to find reliable biomarkers and to understand their molecular mechanisms in GC. In this study, we first confirmed that LINC00941was up-regulated in GC tumor tissues compared with adjacent normal tissues by RT-PCR, and found that the expression level of LINC00941 was correlated with invasion depth, lymphatic metastasis, and the TNM stage of patients with GC. Furthermore, by performing enrichment analysis based on the co-expression network and regulatory network, we found that LINC00941 was associated with cancer related biological processes such as cell cycle, cell communication, cell migration, cell division, as well as processes associated with the immune system. Our results suggested that LINC00941 may be a potential novel biomarker for therapeutic or diagnostic of GC.

Downregulation of c-Met expression does not enhance the sensitivity of gastric cancer cell line MKN-45 to gefitinib

The aim of the present study was to investigate the effect of downregulation of the c‑Met gene on signal transduction and apoptosis in gastric cancer MKN‑45 cells; furthermore, the study aimed to determine whether altered c‑Met gene expression affected MKN‑45 sensitivity to gefitinib. Three c‑Met‑specific small interfering RNAs (siRNAs) were synthesized and transfected into MKN‑45 cells. Messenger RNA (mRNA) and protein levels of c‑Met and its downstream signaling molecules [phosphoinositide 3‑kinase (PI3K) and AKT] were examined using reverse transcription polymerase chain reaction and western blot analysis 48 h following transfection. Cell apoptosis was evaluated using Annexin‑V/propidium iodide double staining and fluorescence‑activated cell sorting analysis. An MTT assay was performed in order to measure the 50% inhibitory concentration (IC50) of gefitinib on MKN‑45 cells. The results of the present study demonstrated that 48 h post‑transfection with c‑Met siRNA, MKN‑45 cells showed significantly downregulated expression of c‑Met mRNA and protein as well as an increased rate of apoptosis (P<0.05). In addition, following c‑Met siRNA transfection mRNA and protein levels of PI3K and AKT were not significantly altered in MKN‑45 cells (P>0.05); however, a marked decrease in the expression levels of phosphorylated (p)‑PI3K and p‑AKT was observed (P<0.05). Furthermore, the IC50 of gefitinib in MKN‑45 cells was not significantly decreased. In conclusion, knockdown of the c‑Met gene promoted gastric cancer cell apoptosis and inhibited downstream p‑PI3K and p‑AKT; however, the sensitivity of MKN‑45 cells to gefitinib was not increased.

Prognostic role of human epidermal growth factor receptor in gastric cancer: a systematic review and meta-analysis

BACKGROUND AND AIMS

Human epidermal growth factor receptor (EGFR) and HER2 (ErbB2) both belong to EGFR family, which are overexpressed in a significant proportion of cases of gastric cancer (GC). Various studies have evaluated the prognostic value of EGFR or HER level in GC. However, the overall test performance remains unclear. We undertook this study to perform a systematic review and meta-analysis of prognostic cohort studies evaluating the use of EGFR or HER2 as a predictor of survival time in patients with GC.

METHODS

Eligible studies were identified through multiple search strategies. Studies were assessed for quality using the Newcastle-Ottawa Tool. Data were collected comparing overall survival (OS) in patients with high and low EGFR or HER2 level. Studies were pooled and summary hazard ratios were calculated.

RESULTS

Studies were listed twice if they provided overall survival data for both EGFR and HER2. Eight studies (seven for EGFR and eight for HER2) were included. Two distinct groups were pooled for analysis and revealed that high EGFR, HER2 levels predicted poor overall (HR = 1.66, 95% CI: 1.35-2.02) and (HR = 1.43, 95% CI: 1.09-1.88) survival. No publication bias was found.

CONCLUSIONS

This meta-analysis result suggested that EGFR or HER2 should have significant predictive ability for estimating overall survival in GC patients and may be useful for defining prognosis of GC patients.

MicroRNA-610 inhibits the migration and invasion of gastric cancer cells by suppressing the expression of vasodilator-stimulated phosphoprotein

Vasodilator-stimulated phosphoprotein (VASP) has been implicated in the establishment of cancerous phenotypes. However, the role of VASP in gastric cancer progression and metastasis remains poorly understood. Here, we demonstrated that VASP was upregulated by epidermal growth factor (EGF) and promoted the migration and invasion of gastric cancer cells. Then we explored the regulatory mechanisms responsible for high expression of VASP in gastric cancer. Based on miRNA expression profiling of the paired gastric cancer tissues and their adjacent non-tumour gastric tissues 18 miRNAs were identified including microRNA-610 (miR-610) which were down-regulated in gastric cancer. Next, we observed an inverse correlation between VASP and miR-610 expression levels in gastric cancer cells after EGF stimulation. Then we performed bioinformatics analysis, Western blot and reverse transcription polymerase chain reaction (RT-PCR) analysis and luciferase assay to establish that miR-610 directly targets VASP 3'-UTR and inhibits its expression. Functionally, we demonstrated that miR610-mediated inhibition of VASP expression resulted in a significant reduction in the migration and invasion properties of gastric cancer cells. The identification of miR-610 as a novel miRNA regulated by EGF that targets VASP in gastric cancer cells suggests that EGF-miR610-VASP axis may be exploited for therapeutic intervention to inhibit gastric cancer progression and metastasis.

An EGFR inhibitor enhances the efficacy of SN38, an active metabolite of irinotecan, in SN38-refractory gastric carcinoma cells

BACKGROUND

Acquired drug resistance to irinotecan is one of the significant obstacles in the treatment of advanced gastric cancer. This study was performed to clarify the effect of epidermal growth factor receptor (EGFR) inhibitors in combination with SN38, an active metabolite of irinotecan, on the proliferation of irinotecan-refractory gastric cancer.

METHODS

Two irinotecan-resistant gastric cancer cell lines, OCUM-2M/SN38 and OCUM-8/SN38 were, respectively, established by stepwise exposure to SN38 from the parent gastric cancer cell lines OCUM-2M and OCUM-8. The combination effects of two EGFR inhibitors, gefitinib and lapatinib, with SN38 on proliferation, apoptosis, and cell cycle on gastric cancer cells were examined.

RESULTS

Gefitinib or lapatinib showed synergistic anti-tumour effects against OCUM-2M/SN38 and OCUM-8/SN38 cells when used in combination with SN38, but not against OCUM-2M or OCUM-8 cells. SN38 increased the expression of EGFR and HER2 in OCUM-2M/SN38 and OCUM-8/SN38 cells. The combination of an EGFR inhibitor and SN38 significantly increased the levels of apoptosis-related molecules, caspase-6, p53, and DAPK-2, and resulted in the induction of apoptosis of irinotecan-resistant cells. The EGFR inhibitors increased the S-phase and decreased the UGT1A1 and ABCG expression in irinotecan-resistant cells. The SN38 plus Lapatinib group more effectively suppressed in vivo tumour growth by OCUM-2M/SN38 cells than either alone group.

CONCLUSION

The combination treatment with an EGFR inhibitor and irinotecan might produce synergistic anti-tumour effects for irinotecan-refractory gastric cancer cells. The regulation of SN38 metabolism-related genes and cell cycle by EGFR inhibitors might be responsible for the synergism.

Clinical significance of EGFR expression in Chinese gastric cancer patients

AIM: To investigate the correlation between epidermal growth factor receptor (EGFR) protein expression and clinicopathological parameters in patients with gastric cancer.

METHODS: The expression of EGFR protein in 775 gastric adenocarcinoma specimens was examined by immunohistochemistry using the EliVisionTM plus kit.

RESULTS: The positive rate of EGFR protein overexpression in gastric adenocarcinoma was 17.03% (132/775). EGFR protein overexpression is associated with tumor invasion depth, histotype, differentiation, and lymph node metastasis (all P < 0.05), but not with sex, age, tumor site, TNM stage, and distant metastasis (all P > 0.05). Multivariate analysis demonstrated that tumor invasion depth, histotype, differentiation, and lymph node metastasis were significant predictors of EGFR protein overexpression in gastric cancer (all P < 0.05).

CONCLUSION: Detection of EGFR protein expression can be used to assess the malignant biological behavior and prognosis of gastric cancer and therefore provides a theoretical target for therapy of gastric cancer.