Hongyan Cheng

Red and Processed Meat Intake Is Associated with Higher Gastric Cancer Risk: A Meta-Analysis of Epidemiological Observational Studies

Background Red and processed meat was concluded as a limited-suggestive risk factor of gastric cancer by the World Cancer Research Fund. However, recent epidemiological studies have yielded inconclusive results. Methods We searched Medline, EMBASE, and the Cochrane Library from their inception to April 2013 for both cohort and case-control studies which assessed the association between red and/or processed meat intake and gastric cancer risk. Study-specific relative risk estimates were polled by random-effect or fixed-effect models. Results Twelve cohort and thirty case-control studies were included in the meta-analysis. Significant associations were found between both red (RR: 1.45, 95% CI: 1.22–1.73) and processed (RR: 1.45, 95% CI: 1.26–1.65) meat intake and gastric cancer risk generally. Positive findings were also existed in the items of beef (RR: 1.28, 95% CI: 1.04–1.57), bacon (RR: 1.37, 95% CI: 1.17–1.61), ham (RR: 1.44, 95% CI: 1.00–2.06), and sausage (RR: 1.33, 95% CI: 1.16–1.52). When conducted by study design, the association was significant in case-control studies (RR: 1.63, 95% CI: 1.33–1.99) but not in cohort studies (RR: 1.02, 95% CI: 0.90–1.17) for red meat. Increased relative risks were seen in high-quality, adenocarcinoma, cardia and European-population studies for red meat. And most subgroup analysis confirmed the significant association between processed meat intake and gastric cancer risk. Conclusions Our findings indicate that consumption of red and/or processed meat contributes to increased gastric cancer risk. However, further investigation is needed to confirm the association, especially for red meat.

MicroRNA-21 is a novel promising target in cancer radiation therapy

MicroRNAs (miRNAs) represent an important nonprotein part of the human genome in tumor biology. Among the several types of miRNAs, microRNA-21 (miR-21) is dysregulated in several types of cancer and plays a key role in carcinogenesis, recurrence, and metastasis. Thus, it can be a potential target for cancer therapy including radiation therapy. In this review, we focus on miR-21, which has been identified in human cancer tissues, to suggest reasonable strategies for future research. miR-21 may have an influence on cell cycle, DNA damage repair, apoptosis, autophagy, and hypoxia of cancer during irradiation. We review the use of miR-21 in cancer radiation therapy and describe the known functions and possible underlying molecular mechanisms of miR-21 in radiosensitivity and radioresistance. Furthermore, the current and potential future applications of miR-21 in cancer radiation therapy are also discussed.

Berberine enhances radiosensitivity of esophageal squamous cancer by targeting HIF-1α in vitro and in vivo.

Radiation therapy is an important treatment approach for esophageal squamous cell carcinoma (ESCC). However, how to promote radiation sensitivity in ESCC remains a challenge. This study aimed to evaluate the effects of berberine, a common used Chinese medicine, on the radiosensitivity of ESCC. ECSS cell line ECA109 and TE13 were subjected to hypoxia and/or ionizing radiation (IR), in the presence or absence of berberine treatment. Cell growth and survival, and apoptosis were evaluated. In addition, ECA109 cells were xenografted into nude mice and subjected to IR and/or berberine treatment. The expression of HIF-1α and VEGF was detected by western blot and immunohistochemical analysis. Our results showed that berberine increased radiosensitivity of ESCC cells and xenografts, and this was associated with the inhibition of HIF-1α and VEGF expression. These data suggest that berberine may be a potential radiotherapy sensitization drugs due to its significant anti-hypoxia activity.

Autophagy and its function in radiosensitivity.

Autophagy differs from apoptosis and is independent of phagocytes by the appearance of autophagosomes, autolysosomes, and complete nuclei in the cell. This process significantly contributes to the antineoplastic effects of radiation. Radiation is an important strategy in cancer treatment; however, many types of cancer show radioresistance. The effects of radiotherapy are affected by factors, including the degree of tumor tissue hypoxia, the ability to repair DNA damage, and the presence of cancer stem cells. We review the relationships among autophagy, the three factors in cancer radiation, and the possible underlying molecular mechanisms. The therapeutic implications of these relationships and mechanisms in clinical settings are also discussed.

STAT3 inhibitor NSC74859 radiosensitizes esophageal cancer via the downregulation of HIF-1α

Radiotherapy is the main therapy for inoperable and locally advanced esophageal squamous cell carcinoma (ESCC). However, radioresistance in ESCC remains a challenge. The aim of this study is to investigate the radiosensitizing effects of STAT3 inhibitor NSC74859 on ESCC and explore the underlying mechanisms. ECA109 and TE13 cells were exposed to hypoxia, and treated with NSC74859 or radiation, alone or in combination. Cell proliferation, survival, apoptosis, and double-stranded DNA breaks (DSBs) were examined. Nude mice model of ECA109 xenograft was treated with radiation and/or NSC74859. The levels of STAT3, p-STAT3, HIF-1α, and VEGF were detected by Western blot analysis. NSC74859 efficiently radiosensitized ESCC cells and xenografts in nude mice, and inhibited hypoxia-/radiation-induced activation of STAT3 and upregulation of HIF-1α and VEGF expression. NSC74859 confers radiosensitivity in ESCC via the inhibition of STAT3 activation and the downregulation of HIF-1α and VEGF expression. NSC74859 may become a promising radiosensitizer for ESCC radiotherapy.

Berberine radiosensitizes human nasopharyngeal carcinoma by suppressing hypoxia-inducible factor-1α expression.

Abstract Conclusion: Berberine confers radiosensitivity on nasopharyngeal carcinoma (NPC) and this is associated with the down-regulation of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) expression. Berberine could be a promising radiosensitizer for NPC radiotherapy. Objectives: NPC has a poor prognosis. Radiotherapy as first-line therapy significantly increases patient survival but radioresistance is a problem. This study aimed to investigate the radiosensitizing effects of berberine on NPC and explore the underlying mechanisms. Methods: CNE-1 and CNE-2 cells were exposed to hypoxia and treated with berberine at different concentrations. The MTT assay, clonogenic assay, and flow cytometry were performed to analyze cell proliferation, colony formation, and apoptosis. The expression of HIF-1α and VEGF was assessed by Western blot and immunofluorescence analysis. Male nude mice inoculated subcutaneously with CNE-2 cells were used to examine the sensitizing effects of berberine in vivo. Results: Berberine efficiently radiosensitized NPC cells and xenografts in mice, and inhibited hypoxia/radiation-induced up-regulation of HIF-1α and VEGF expression.

Polymorphisms in XPD Gene Could Predict Clinical Outcome of Platinum-Based Chemotherapy for Non-Small Cell Lung Cancer Patients: A Meta-Analysis of 24 Studies

Objective Xeroderma pigmentosum group D (XPD) is an essential gene involved in the nucleotide excision repair (NER) pathway. Two commonly studied single nucleotide polymorphisms (SNPs) of XPD (Lys751Gln, A>C, rs13181; Asp312Asn, G>A, rs1799793) are implicated in the modulation of DNA repair capacity, thus related to the responses to platinum-based chemotherapy. Here we performed a meta-analysis to better evaluate the association between the two XPD SNPs and clinical outcome of platinum-based chemotherapy in non-small cell lung cancer (NSCLC) patients. Methods A comprehensive search of PubMed database was conducted to identify relevant articles. Primary outcomes included objective response (i.e., complete response + partial response vs. stable disease + progressive disease), progression-free survival (PFS) and overall survival (OS). The pooled and 95% confidence intervals (CIs) of ORs (odds ratios) and HRs (hazard ratios) were estimated using the fixed or random effect model. Results Twenty-four studies were eligible according to the inclusion criteria. None of the XPD Lys751Gln/Asp312Asn polymorphisms was associated with objective response, PFS or OS in NSCLC patients treated with platinum drugs. However, in stratified analysis by ethnicity, the XPD Lys751Gln (A>C) polymorphism was not significantly associated with increased response in Caucasians (OR = 1.35, 95%CI = 1.0–1.83, P = 0.122 for heterogeneity) but was associated with decreased PFS in Asians (HR = 1.39, 95%CI = 1.07–1.81, P = 0.879 for heterogeneity). Furthermore, a statistically significant difference existed in the estimates of effect between the two ethnicities (P = 0.014 for TR; P<0.001 for PFS). Conclusions XPD Lys751Gln (A>C) may have inverse predictive and prognostic role in platinum-based treatment of NSCLC according to different ethnicities. Further studies are needed to validate our findings.

Genetic variants and risk of esophageal squamous cell carcinoma: A GWAS-based pathway analysis

This study was designed to identify candidate single-nucleotide polymorphisms (SNPs) that may affect the susceptibility to esophageal squamous cell carcinoma (ESCC) and elucidate their potential mechanisms to generate SNP-to-gene-to-pathway hypotheses. A genome-wide association study (GWAS) dataset for ESCC, which included 453,852 SNPs from 1898 ESCC patients and 2100 control subjects of Chinese population, was reviewed. The identify candidate causal SNPs and pathways (ICSNPathway) analysis identified seven candidate SNPs, five genes, and seven pathways, which together revealed seven hypothetical biological mechanisms. The three strongest hypothetical biological mechanisms were as follows: rs4135113→TDG→BASE EXCISION REPAIR; rs1800450→MBL2→MONOSACCHARIDE BINDING; and rs3769823→CASP8→d4gdiPathway. The GWAS dataset was evaluated using the ICSNPathway, which showed seven candidate SNPs, five genes, and seven pathways that may contribute to the susceptibility of patients to ESCC.

Small-molecule survivin inhibitor YM155 enhances radiosensitization in esophageal squamous cell carcinoma by the abrogation of G2 checkpoint and suppression of homologous recombination repair

BackgroundSurvivin is overexpressed in cancer cells and plays a crucial role in apoptosis evasion. YM155, a small-molecule inhibitor of survivin, could enhance the cytotoxicity of various DNA-damaging agents. Here, we evaluated the radiosensitizaion potential of YM155 in human esophageal squamous cell carcinoma (ESCC).MethodsCell viability was determined by CCK8 assay. The radiosensitization effect of YM155 was evaluated by clonogenic survival and progression of tumor xenograft. Cell cycle progression was determined by flow cytometric analysis. Radiation-induced DNA double strand break (DSB) and homologous recombination repair (HRR) were detected by the staining of γ-H2AX and RAD51, respectively. Expression of survivin and cell cycle regulators was detected by Western blot analysis.ResultsYM155 induced radiosensitization in ESCC cell lines Eca109 and TE13, associated with the abrogation of radiation induced G2/M checkpoint, impaired Rad51 focus formation, and the prolongation of γ-H2AX signaling. G2/M transition markers, including the activation of cyclinB1/Cdc2 kinase and the suppression of Cdc2 Thr14/Tyr15 phosphorylation were induced by YM155 in irradiated cells. The combination of YM155 plus irradiation delayed the growth of ESCC tumor xenografts to a greater extent compared with either treatment modality alone.ConclusionsOur findings suggest that the abrogation of G2 checkpoint and the inhibition of HRR contribute to radiosensitization by YM155 in ESCC cells.

Gambogic acid enhances the radiosensitivity of human esophageal cancer cells by inducing reactive oxygen species via targeting Akt/mTOR pathway

Radiotherapy is a widespread treatment in human solid tumors. However, therapy resistance and poor prognosis are still problems. Gambogic acid (GA), extracted from the dried yellow resin of gamboges, has an anticancer effect against various types of cancer cells. To explore the radiosensitivity of GA on esophageal cancer cell line TE13, cell viability was tested by Cell Counting Kit-8 (CCK-8) assay, colony formation assay was used to assess the effects of GA on the radiosensitivity of TE13, and flow cytometry was performed to meter the percentage of apoptosis. The protein levels of microtubule-associated protein 1 light chain 3 (LC3), caspase3, caspase8, casepase9, pAkt, and p-mammalian target of rapamycin (p-mTOR) were tested using Western blot. The distribution of LC3 was detected by immunofluorescence. Additionally, we also examined reactive oxygen species (ROS) expression by laser scanning confocal microscope (LSCM). The cells were transfected with adenovial vector to monitor the autophagy through the expression of green fluorescent protein (GFP–red fluroscent protein (RFP)–LC3. The rates of apoptotic cells in combined-treated TE13 increased significantly compared with the control groups in accordance with the results of Western blot. The clonogenic survival assay showed that GA enhances radiosensitivity with a sensitizing enhancement ratio (SER) of 1.217 and 1.436 at different concentrations. The LC3-II protein level increased in the combined group indicating the increase of autophagy incidence, and the results of GFP–RFP–LC3 experiment showed that GA may block the process of autophagic flux in TE13 cells. Moreover, we successfully demonstrated that ROS is involved in the induction of autophagy. ROS-mediated autophagy depends on the inhibition of the Akt/mTOR pathway. Taken together, GA induced radiosensitivity involves autophagy and apoptosis which are regulated by ROS hypergeneration and Akt/mTOR inhibition.