Liver X receptors agonist T0901317 exerts ferroptosis sensitization in cancer.

Numerous studies have confirmed the anticancer effects of ferroptosis on a wide range of tumors, specifically in providing new perspectives for tackling drug resistance and treating refractory tumors. Notably, mechanisms of improving tumor susceptibility to ferroptosis have been a focus of current research. This study discovered that co-treatment of LXRS agonist T0901317 and ferroptosis inducers (FINs) significantly inhibited the proliferation of cancer cells, this inhibition effect could be reversed by specific inhibitors of ferroptosis and accompanied by elevated lipid peroxides. Glutathione peroxidase 4 (GPX4) regulates T0901317 induced ferroptotic sensitization, and its overexpression dramatically reverses the joint anticancer effect of T0901317 and FINs. Furthermore, xenograft model results highly confirmed the ferroptotic sensitization effect of T0901317 in vivo. In summary, our findings indicate that drug combination and ferroptosis induction strategies provide novel options for cancer therapy.

Risk factors of lymphovascular invasion in hypopharyngeal squamous cell carcinoma and its influence on prognosis.

PURPOSE: Lymphatic vascular invasion (LVI) is a poor prognostic factor for hypopharyngeal squamous cell carcinoma (HPSCC), but the risk factors of LVI and its relationship with clinicopathological of HPSCC remain unclear. This study aims to explore these issues. METHODS: We retrospectively analyzed the clinicopathological data of 170 patients with HPSCC from January 2011 to December 2015. The relationship between LVI and clinicopathologic was analyzed by Chi-square test or Fisher's exact test. The risk factors of LVI were examined using a logistic regression model, while risk factors of survival rate were carried out using the Cox regression model. RESULTS: LVI occurred in 59 cases (34.7%). In multivariate analysis, T3-4 stage (HR = 2.877; 95% CI: 1.379-6.004; p = 0.005), N2-3 stage (HR = 2.325; 95% CI: 1.120-4.824; p = 0.024), and poor differentiation (HR = 2.983; 95% CI: 1.229-7.242; p = 0.016) were independent risk factors for LVI; positive LVI was an independent risk factor for local recurrence (HR = 2.488; 95% CI: 1.150-5.383; p = 0.021), poor 5-year OS (HR = 0.375; 95% CI: 0.232-0.606; p < 0.000), DSS (HR = 0.374; 95% CI: 0.235-0.595; p < 0.000), and DFS (HR = 0.454; 95% CI:0.254-0.813; p = 0.008). CONCLUSION: T3-4 stage, N2-3 stage and poor differentiation are independent risk factors for LVI of HPSCC; LVI increases the local recurrence and regional recurrence rate, and decreases 5-year OS, DFS and DSS of HPSCC.

GPX2 overexpression indicates poor prognosis in patients with hepatocellular carcinoma.

Glutathione peroxidase 2 has important role of tumor progression in lots of carcinomas, yet little is known about the prognosis of glutathione peroxidase 2 in hepatocellular carcinoma. Glutathione peroxidase 2 expression was assessed by immunohistochemistry in hepatocellular carcinoma tissues. The association between glutathione peroxidase 2 expression with clinicopathological/prognostic value was examined. Glutathione peroxidase 2 overexpression was correlated with alpha-fetoprotein level, larger tumor, BCLC stage, and tumor recurrence. Kaplan-Meier analysis showed that glutathione peroxidase 2 was an independent predictor for overall survival and time to recurrence. glutathione peroxidase 2 overexpression was correlated with poor prognosis in patient subgroups stratified by tumor size, differentiation, tumor-node-metastasis, and BCLC stage. Moreover, stratified analysis showed that tumor-node-metastasis stage-I patients with high glutathione peroxidase 2 expression had poor prognosis than those with low glutathione peroxidase 2 expression. Additionally, combination of glutathione peroxidase 2 and serum alpha-fetoprotein was correlated with prognosis in hepatocellular carcinoma. In conclusion, glutathione peroxidase 2 overexpression contributes to poor prognosis of hepatocellular carcinoma patients and helps to identify the high-risk hepatocellular carcinoma patients.

Corrigendum to "Efficacy and Safety of First-Line Immunotherapy in Combination with Chemotherapy for Patients with Extensive-Stage Small Cell Lung Cancer: A Systematic Review and Network Meta-Analysis".

[This corrects the article DOI: 10.1155/2020/2368164.].

The efficacy and safety of PD-1/PD-L1 inhibitors in patients with recurrent or metastatic nasopharyngeal carcinoma: A systematic review and meta-analysis.

OBJECTIVES: There is currently no effective salvage therapeutic modality that improves the survival outcomes of patients with recurrent or metastatic nasopharyngeal carcinoma. However, the programmed cell death protein 1 (PD-1) and its ligand (PD-L1) inhibitors may provide clinical benefit for these advanced patients. MATERIALS AND METHODS: The databases, including PubMed, Web of Science, EMBASE and Cochrane Library, were systematically searched up to Nov 5, 2019. Data of objective response rate (ORR), disease control rate (DCR), progression-free survival (PFS) rate, overall survival (OS) rate, and drug-related adverse events were extracted and pooled meta-analyzed. RESULTS: From 71 search records, eight studies were included in the systematic review, of which three were eligible for final meta-analysis. In recurrent or metastatic nasopharyngeal carcinoma patients treated with anti-PD-1 therapy, the pooled ORR was 27% (95% confidence interval [CI] 19-36%), DCR was 63% (95% CI 50-75%), 6 months PFS rate was 49% (95% CI 40-58%), 1-year PFS rate was 25% (95% CI 19-32%), 1-year OS rate was 61% (95% CI 49-72%). The pooled incidences of any grade and grade ≥ 3 drug-related adverse events were 94% and 20% respectively. CONCLUSION: We present the aggregate response rates, survival rates and incidences of drug-related adverse events for recurrent or metastatic nasopharyngeal carcinoma patients receiving PD-1/PD-L1 blockage treatment, which could provide useful information for future design of clinical studies. There is a need for more randomized controlled studies with head-to-head comparison of PD-1/PD-L1 inhibitors and traditional chemotherapeutic strategies to enable better recommendations for optimal advanced nasopharyngeal carcinoma treatment.

Efficacy and Safety of First-Line Immunotherapy in Combination with Chemotherapy for Patients with Extensive-Stage Small Cell Lung Cancer: A Systematic Review and Network Meta-Analysis.

BACKGROUND: The prognosis of patients with extensive-stage small cell lung cancer (SCLC) is poor. Adding an immune checkpoint inhibitor (ICI) to chemotherapy may exert a synergistic effect and improve survival outcomes. However, for treatment-naive extensive-stage SCLC patients, the efficacy of immunotherapy in combination with cytotoxic chemotherapy remains controversial. OBJECTIVE: To evaluate the benefits and risks of the combination of immunotherapy and chemotherapy and to assess the comparative effectiveness of different first-line treatment strategies for extensive-stage SCLC. METHODS: PubMed, Web of Science, EMBASE, and Cochrane Library were searched for randomized clinical trials studying different immunotherapeutics for patients with previously untreated extensive-stage SCLC up to Feb 16, 2020. The primary outcomes were overall survival (OS) and progression-free survival (PFS), and the secondary outcomes were objective response rate (ORR), disease control rate (DCR), and adverse events. RESULTS: We identified 141 published records, and 4 studies (comprising 2202 patients) were included in the analysis. Immunotherapy (including ipilimumab, atezolizumab, and durvalumab) plus chemotherapy was associated with better OS (hazard ratio (HR) 0.84, 95% confidence interval (CI) 0.75-0.93; risk ratio (RR) 0.90, 95% CI 0.81-1.00) and PFS (HR: 0.81, 95% CI 0.74-0.88; RR 0.96, 95% CI 0.93-0.99) than placebo plus chemotherapy. The addition of immunotherapy to chemotherapy showed similar improvement in ORR, DCR, and adverse events versus placebo plus chemotherapy. On the surface under the cumulative ranking (SUCRA) analysis, the anti-PD-L1 agent, atezolizumab, had the highest likelihood of achieving improved OS (93.4%) and PFS (95.0%). CONCLUSION: In the first-line setting, combining immunotherapy with chemotherapy is better than standard chemotherapy in terms of OS and PFS. Across the eligible studies, PD-L1 inhibitors might be preferred. Further explorations of more ICIs in the first-line treatment for extensive-stage SCLC patients should be needed.

Differential IL-4/Stat6 activities correlate with differential expression of regulatory genes SOCS-1, SHP-1, and PP2A in colon cancer cells.

PURPOSE: To investigate potential differences in the expression of Stat6 regulatory genes that may influence IL-4/Stat6 activities (phenotypes) in colon cancer cells. METHODS: RT-PCR method was employed to examine the constitutive mRNA expression of Stat6 negative regulators SOCS-1 and SHP-1, and positive regulator PP2A in colon cancer cell lines HT-29 and Caco-2. Stat6 protein expression and nuclear phosphorylation were detected using Western blotting. RESULTS: Caco-2 cells carrying inactive Stat6(null) phenotype showed normal constitutive expression of Stat6 but decreased phosphorylation of nuclear Stat6 compared with HT-29 cells carrying active Stat6(high) phenotype. Stat6(null) Caco-2 cells expressed increased levels of mRNA and protein of SOCS-1 and SHP-1, and decreased mRNA expression of PPP2CA and PPP2CB, encoding two critical subunits of PP2A. CONCLUSIONS: Constitutively increased expression of Stat6 negative regulators SOCS-1 and SHP-1, together with decreased expression of positive regulator PP2A, may play a role in forming the inactive Stat6(null) phenotype in colon cancer cells.

The effects and safety of PD-1/PD-L1 inhibitors on head and neck cancer: A systematic review and meta-analysis.

BACKGROUND: Inhibitors of programmed cell death-1 (PD-1) and its ligand (PD-L1) have been increasingly used in head and neck cancer therapy and reported to improve the outcomes with an acceptable safety profile. This systematic review and meta-analysis was conducted to assess the benefit and risk of PD-1/PD-L1 inhibitors in patients with head and neck cancer. METHOD: The PubMed, Cochrane Library, EMBASE and Web of Science databases were systematically searched to find potentially eligible studies up to May 30, 2019. Primary outcomes were overall survival (OS), progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR) and adverse events. RESULTS: Overall, this analysis consisted of nine eligible studies, with two randomized controlled trials and seven single arm trials. In the treatment of recurrent or metastatic head and neck cancer, PD-1 inhibitors showed significantly lower relative risk of death than standard-of-care therapy (odds ratio [OR] = 0.60, 95% confidence interval [CI]: 0.44-0.82, I2  = 0%, P = .001). Programmed cell death-1 inhibitors also decreased the risk of disease progression, however, there was no statistically significant difference of PFS between the treatments (OR = 0.69, 95% CI: 0.48-1.01, I2  = 0%, P = .05). Subgroup analysis showed that human papillomavirus (HPV) positive patients had higher response rates than HPV negative patients in PD-1/PD-L1 inhibitors-treated population (ORR: 18.8% vs 12.2%; DCR: 42.8% vs 34.4%). The most common any-grade and grade ≥3 treatment-related adverse events were fatigue (14.7%, 95% CI: 12.3%-17.1%) and aspartate aminotransferase increased (1.6%, 95% CI: 0.3%-2.9%), respectively. CONCLUSION: Programmed cell death-1 inhibitors prolonged OS in comparison with standard-of-care therapy in recurrent or metastatic head and neck cancer patients. Human papillomavirus positive patients were superior to HPV negative patients in the treatment of PD-1/PD-L1 inhibitors. More phase III randomized controlled trials are warranted to confirm our findings.

LINC01939 inhibits the metastasis of gastric cancer by acting as a molecular sponge of miR-17-5p to regulate EGR2 expression.

Accumulating evidence have suggested that long noncoding RNAs (lncRNAs) are known to regulate diverse tumorigenic processes. Recently, a novel lncRNA LINC01939 was underexpressed and emerged as a tumor suppressive lncRNA in gastric cancer (GC). In this study, we aimed to investigate the biological function and molecular mechanism of LINC01939 in GC. We found that LINC01939 expression was significantly downregulated in GC tissues and cell lines. Low expression of LINC01939 was correlated with tumor metastasis and shorter survival in GC patients. Functionally, LINC01939 overexpression remarkably inhibited the invasion and migration of GC cells in vitro and in vivo. Mechanistically, LINC01939 regulated the expression of early growth response 2 (EGR2) protein by competitively binding to miR-17-5p. Upregulation of miR-17-5p reversed GC metastasis and EMT process caused by LINC01939 by rescue analysis. Taken together, these results suggested that LINC01939 repressed GC invasion and migration by functioning as a ceRNA for miR-17-5p to regulate EGR2 expression. Our findings provided a novel prognostic marker and therapeutic target for GC patients.

IL-4/Stat6 activities correlate with apoptosis and metastasis in colon cancer cells.

IL-4-induced Stat6 signaling is active in a variety of cell types and plays a role in cell proliferation/growth and resistance to apoptosis. Using EMSA, we identified differential IL-4/Stat6 activities in colorectal cancer cell lines, HT-29 being active Stat6(high) phenotype and Caco-2 being defective Stat6(null) phenotype, respectively. Active Stat6(high) HT-29 cells exhibited resistance to apoptosis by flowcytometry and aggressive metastasis by Transwell assay compared with defective Stat6(null) Caco-2 cells. Comparing one another using RT-PCR, Stat6(high) HT-29 cells expressed more mRNA of anti-apoptotic and pro-metastatic genes Survivin, MDM2, and TMPRSS4, while Stat6(null) Caco-2 cells expressed more mRNA of pro-apoptotic and anti-metastatic genes BAX, CAV1, and P53, respectively. This is the first study describing correlations of IL-4/Stat6 activities with apoptosis and metastasis in colon cancer. These findings, together with the observation of constitutive Stat6 activation in many human malignancies, suggest that Stat6 activities could be a biomarker for cancer cell's invasive/metastatic capability.

IL-4-induced Stat6 activities affect apoptosis and gene expression in breast cancer cells.

IL-4-induced Stat6 signaling is active in a variety of cell types, including immune cells and cancer cells, and plays an important role in the regulation of gene expression. Using EMSA gel shift assay and an antibody to Stat6, we phenotyped two breast cancer cell lines, ZR-75-1 being active Stat6(high) phenotype and BT-20 being defective Stat6(null) phenotype, respectively. Breast cancer cells carrying Stat6(null) phenotype exhibited increased spontaneous apoptosis compared with those carrying Stat6(high) phenotype. Expression microarray analyses demonstrated that IL-4 upregulated CCL26, SOCS1, CISH, EGLN3, and SIDT1, and downregulated DUSP1, FOS, and FOSB, respectively, in these breast cancer cells. Among those genes, CCL26 and SOCS1 were known genes regulated by IL-4/Stat6 pathway, but CISH, EGLN3, SIDT1, DUSP1, FOS, and FOSB were novel genes demonstrated to be IL-4 responsive for the first time. IL-4 also upregulated 38 genes unique to Stat6(null) BT-20 cells and 23 genes unique to Stat6(high) ZR-75-1 cells, respectively. Furthermore, Stat6(high) and Stat6(null) cells showed very different profiles of constitutively expressed genes relevant to apoptosis and metastasis among others, which serve as a valuable expression database and warrant for detailed studies of IL-4/Stat6 pathway in breast cancer.

Melatonin suppresses thyroid cancer growth and overcomes radioresistance via inhibition of p65 phosphorylation and induction of ROS.

Thyroid cancer is the most common endocrine carcinoma with increasing incidence worldwide and anaplastic subtypes are frequently associated with cancer related death. Radioresistance of thyroid cancer often leads to therapy failure and cancer-related death. In this study, we found that melatonin showed potent suppressive roles on NF-κB signaling via inhibition of p65 phosphorylation and generated redox stress in thyroid cancer including the anaplastic subtypes. Our data showed that melatonin significantly decreased cell viability, suppressed cell migration and induced apoptosis in thyroid cancer cell lines in vitro and impaired tumor growth in the subcutaneous mouse model in vivo. By contrast, irradiation of thyroid cancer cells resulted in elevated level of phosphorylated p65, which could be reversed by cotreatment with melatonin. Consequently, melatonin synergized with irradiation to induce cytotoxicity to thyroid cancer, especially in the undifferentiated subgroups. Taken together, our results suggest that melatonin may exert anti-tumor activities against thyroid carcinoma by inhibition of p65 phosphorylation and induction of reactive oxygen species. Radio-sensitization by melatonin may have clinical benefits in thyroid cancer.

HOXC6 predicts invasion and poor survival in hepatocellular carcinoma by driving epithelial-mesenchymal transition.

Aberrant expression of HOXC6 has been reported in several malignant tumors, yet little is known about the value of HOXC6 in invasion and prognosis of hepatocellular carcinoma (HCC). HOXC6 expression was positively correlated with high AFP level, liver cirrhosis, larger tumor, vascular invasion and BCLC stage. Kaplan-Meier analysis revealed that HOXC6 was an independent predictor for overall survival (OS) and time to recurrence (TTR). In addition, HOXC6 status could act as prognostic predictor in different risk subgroups. Moreover, HOXC6 maintained its prognostic value in different ability of invasiveness. Furthermore, combination of HOXC6 and serum AFP could be a potential predictor for survival in HCC patients. Additionally, further study showed that HOXC6 may promote invasion of HCC by driving epithelial-mesenchymal transition (EMT). Knockdown of HOXC6 significantly decreased the migration and invasion of HCC cells and changed the expression pattern of EMT markers. An opposite expression pattern of EMT markers was observed in HOXC6-transfected cells. In addition, immunohistochemistry and RT-PCR results further confirmed this correlation. In conclusion, HOXC6 contributes to invasion by inducing EMT pathway and predicts poor prognosis of HCC. HOXC6/AFP expression may help to distinguish the different risks of HCC patients after hepatectomy.

Analysis of efficacy and prognosis of neoadjuvant chemotherapy and （or） surgery plus radiotherapy for hypopharyngeal squamous cell carcinoma / 临床耳鼻咽喉头颈外科杂志

Objective:To analyze the risk factors that affect the prognosis of patients with hypopharyngeal squamous cell carcinoma（HPSCC） and to compare the efficacy of surgical resection followed by adjuvant radiotherapy（SR） with that of neoadjuvant therapy consisting of platinum-based chemotherapy and fluorouracil combined with either cetuximab or nimotuzumab, followed by SR. The study also aimed to evaluate the overall survival（OS） of patients, their postoperative eating function, tracheostomy decannulation rate, and tumor response to the two neoadjuvant chemotherapies. Methods:A retrospective analysis was performed on the medical records of HPSCC patients who received SR or neoadjuvant therapy followed by SR treatment at the Shanghai General Hospital from 2012 to 2019 and had not undergone any prior treatment. The prognostic factors were analyzed, and the survival analysis of patients who underwent SR treatment with two neoadjuvant chemotherapy regimens was performed. Results:A total of 108 patients were included in the study. The results of the univariate analysis showed that gender（P=0.850） had no significant correlation with the survival rate of HPSCC patients who underwent SR. However, age, smoking history, alcohol consumption history, platelet-to-lymphocyte ratio（PLR）, neutrophil-to-lymphocyte ratio（NLR）, T stage, N stage, neoadjuvant therapy with either cetuximab or nimotuzumab combined with platinum-based chemotherapy and fluorouracil, and histological grade were significantly associated with prognosis（P<0.05）. The multivariate analysis revealed that smoking history, histological grade, and neoadjuvant therapy with either cetuximab or nimotuzumab combined with platinum-based chemotherapy and fluorouracil were independent risk factors affecting the prognosis of HPSCC（P<0.05）. Patients who received neoadjuvant therapy had longer OS than those who underwent SR only（P<0.001）. There was no significant difference in tumor response to the two neoadjuvant therapies and in OS（P>0.05）, and there was no significant difference in the rate of oral feeding and tracheostomy decannulation among the three treatment groups（P>0.05）. Conclusion:Univariate analysis showed that age at tumor onset, smoking history, alcohol consumption history, NLR, PLR, T stage, N stage, whether receiving neoadjuvant chemotherapy, and pathological grade were associated with the prognosis of HPSCC patients receiving SR treatment. Multivariate analysis showed that smoking history, pathological grade, and neoadjuvant chemotherapy were independent risk factors affecting the prognosis. Neoadjuvant chemotherapy with cetuximab or nimotuzumab can prolong the OS of patients, providing a certain basis and reference for the treatment of HPSCC.

CLCA4 inhibits cell proliferation and invasion of hepatocellular carcinoma by suppressing epithelial-mesenchymal transition via PI3K/AKT signaling.

Calcium activated Chloride Channel A4 (CLCA4), as a tumor suppressor, was reported to contribute to the progression of several malignant tumors, yet little is known about the significance of CLCA4 in invasion and prognosis of hepatocellular carcinoma (HCC). CLCA4 expression was negatively correlated with tumor size, vascular invasion and TNM stage. Kaplan-Meier analysis showed that CLCA4 was an independent predictor for overall survival (OS) and time to recurrence (TTR). In addition, CLCA4 status could act as prognostic predictor in different risk of subgroups. Moreover, combination of CLCA4 and serum AFP could be a potential predictor for survival in HCC patients. Furthermore, CLCA4 may inhibit cell migration and invasion by suppressing epithelial-mesenchymal transition (EMT) via PI3K/ATK signaling. Knockdown of CLCA4 significantly increased the migration and invasion of HCC cells and changed the expression pattern of EMT markers and PI3K/AKT phosphorylation. An opposite expression pattern of EMT markers and PI3K/AKT phosphorylation was observed in CLCA4-transfected cells. Additionally, immunohistochemistry and RT-PCR results further confirmed this correlation. Taken together, CLCA4 contributes to migration and invasion by suppressing EMT via PI3K/ATK signaling and predicts favourable prognosis of HCC. CLCA4/AFP expression may help to distinguish different risks of HCC patients after hepatectomy.

Redox-dependent modulation of metformin contributes to enhanced sensitivity of esophageal squamous cell carcinoma to cisplatin.

Glutathione is the major intracellular anti-oxidant against reactive oxygen species and serves as a detoxification essential. The anti-diabetic drug metformin has been showed to exert anti-tumor activity via modulation of redox homeostasis. In this study, we provided evidence that metformin inhibits proliferation and induces apoptosis of esophageal squamous cancer cells. Importantly, we found that metformin acts as pro-oxidant via depletion of intracellular glutathione. Co-treatment with metformin reversed the elevated intracellular glutathione induced by cisplatin and therefore enhanced the sensitivity to cisplatin in vitro and in vivo. Taken together, our data indicate that combination of metformin with cisplatin may represent a novel therapeutic strategy for esophageal squamous cell carcinoma treatment.

Upregulation of the long non-coding RNA PVT1 promotes esophageal squamous cell carcinoma progression by acting as a molecular sponge of miR-203 and LASP1.

Long non-coding RNAs are a group of non-coding RNAs longer than 200 nucleotides and possess diverse functions and exhibit exquisite cell-specific and developmental dynamic expression patterns. The role of the long non-coding RNA PVT1 in esophageal squamous cell carcinoma remains unsolved. Here, we showed that PVT1 expression is significantly up-regulated in ESCC tumor samples compared with their normal counterparts. Knockdown of PVT1 suppressed tumor growth in vitro and in vivo. Further studies revealed that silence of PVT1 lead to up-regulation of miR-203, and vice versa. Moreover, LASP1 was found to be downregulated after knockdown of PVT1 and overexpression of LASP1 attenuated the tumor-suppressive roles of PVT1 knockdown. Our results suggest that PVT1 promote ESCC progression via functioning as a molecular sponge for miR-203 and LASP1 and provide the first evidence of dysregulated PVT1/miR-203/LASP1 axis in ESCC.

Low heme oxygenase-1 expression promotes gastric cancer cell apoptosis, inhibits proliferation and invasion, and correlates with increased overall survival in gastric cancer patients.

Heme oxygenase-1 (HO-1) plays a key role in anti-oxidation, anti-apoptosis, and anti-proliferation in various types of cancers. However, the relationship between HO-1 expression and gastric cancer development remains largely unknown. In this study, the protein expression of HO-1 in human gastric cancer was measured by immunohistochemistry on paraffin sections of 89 paired gastric carcinoma tissues and adjacent non-cancer tissues. The correlation of HO-1 expression with 5-year overall survival rate was estimated. The effects of decreased HO-1 expression by two strands of small interfered RNAs (siRNAs) on cell apoptosis, proliferation, and invasion of gastric cancer cell lines were examined by flow cytometry, the MTT assay, and the cell migration assay, respectively. High expression of HO-1 was detected in 11.2% (10/89) of gastric carcinoma tissues, compared with 1.1% (1/89) in matched adjacent normal tissues, and correlated with a decreased survival rate in gastric cancer patients. There were no significant correlations between HO-1 expression and clinical characteristics. Downregulation of HO-1 expression using two strands of siRNAs promoted apoptosis and inhibited the proliferation and invasion of two gastric cancer cell lines, SGC7901 and MKN-28 cells. This study demonstrated that HO-1 plays a vital role in the development of gastric cancer and may serve as a therapeutic target of this type of cancer.

Low-dose hyper-radiosensitivity in human hepatocellular HepG2 cells is associated with Cdc25C-mediated G2/M cell cycle checkpoint control.

PURPOSE: Although the significance of cell cycle checkpoints in overcoming low-dose hyper-radiosensitivity (HRS) has been proposed, the underlying mechanism of HRS in human hepatocellular cells remains unclear. Therefore, the aim of this study was to characterize HRS inhuman hepatocellular HepG2 cells and to explore the molecular mechanism(s) mediating this response. MATERIALS AND METHODS: HepG2 cells were exposed to various single doses of γ radiation (from 0 Gy to 4 Gy), and then were assayed at subsequent time-points. Survival curves were then generated using a linear-quadratic (LQ) equation and a modified induced repair model (MIRM). The percentage of cells in the G1, G2/M, and S phases of the cell cycle were also examined using propidium iodide (PI) staining and flow cytometry. Levels of total cell division cyclin 25C (Cdc25C) and phosphorylated Cdc25C were examined by Western blotting. RESULTS: Low-dose γ radiation (<0.3 Gy) induced HRS in HepG2 cells, while doses of 0.3, 0.5, and 2.0 Gy γ radiation significantly arrested HepG2 cells in the G2/M phase. While total Cdc25C levels remained unchanged after irradiation, levels of phosphorylated Cdc25C markedly increased 6, 16, and 24 h after treatment with 0.5 or 2.0 Gy radiation, and they peaked after 16 h. The latter observation is consistent with the G2/M arrest that was detected following irradiation. CONCLUSIONS: These findings indicate that low-dose HRS in HepG2 cells may be associated with Cdc25C-mediated G2/M cell cycle checkpoint control.

Evaluation of HO-1 expression, cellular ROS production, cellular proliferation and cellular apoptosis in human esophageal squamous cell carcinoma tumors and cell lines.

Patients with esophageal squamous cell carcinoma (ESCC) have a poor prognosis. However, the related mechanisms are unclear, thus we investigated the expression of HO-1 in ESCC tissue and explored possible mechanisms of tumor progression. Expression of HO-1 was examined by immunohistochemistry in 143 ESCC tumors. The correlation of HO-1 with clinicopathological characteristics was also examined. Two human ESCC cell lines, TE-13 and Eca109 were studied. Silencing of cell line HO-1 by specific small interfering RNA (siRNA) was evaluated using real-time quantitative PCR. Cell line viability, apoptosis and intracellular levels of reactive oxygen species (ROS) after transfection were determined using MTT and flow cytometry, respectively. HO-1, Bax, Bcl-2 and A-caspase-3/-9 expression was evaluated using western blot analyses. We found that HO-1 was expressed in 58 of 143 ESCC tumors, mainly in the cytoplasm. There was a significant association between HO-1 expression and tumor grade (P<0.001). Knockdown of HO-1 expression in cell lines was associated with significantly decreased cellular proliferation (P<0.05) and a higher rate of apoptosis (P<0.001) 48 h after treatment. Treatment of the cell lines with the ROS inhibitor N-acetylcysteine abrogated this effect. Knockdown of HO-1 was associated with increased A-caspase-3 and -9 expression, but no change in Bax or Bcl-2 expression or Bax/Bcl-2 ratio was observed. Thus, the present study identified that ESCC tumors frequently expressed HO-1. Knockdown of HO-1 promoted apoptosis through activation of a ROS-mediated caspase apoptosis pathway.