Kun Tu Yeh

Association of O6-methylguanine-DNA methyltransferase (MGMT) promoter methylation with p53 mutation occurrence in non-small cell lung cancer with different histology, gender, and smoking status

BackgroundO6-methylguanine-DNA methyltransferase (MGMT) promoter methylation has been demonstrated to associate with the G:C→A:T transition mutation in the p53 gene of lung tumors. The purpose of this study is to clarify whether MGMT promoter methylation is not only associated with the shift from the G:C→A:T mutation in the p53 gene but also whether MGMT increases other mutation patterns in lung tumors.Materials and MethodsTo further verify whether a different prevalence of MGMT promoter methylation is observed in lung tumors with a different tumor histology, gender, and smoking status, 220 lung tumors were collected to evaluate the status of MGMT promoter methylation and p53 mutation using methylation-specific PCR (MSP) and direct sequencing, respectively.ResultsThe data shows that a higher prevalence of MGMT promoter methylation was observed in tumors with the G:C→A:T transition or other p53 mutation patterns compared with those with p53 wild-type (P < 0.001 for G:C→A:T; P = 0.015 for other mutation patterns), and this prevalence was more pronounced in tumors from male than from female patients. MGMT promoter methylation in p53 mutation patterns had a different effect on squamous cell carcinomas (SCC) and adenocarcinomas (ADC). Interestingly, the highest prevalence of MGMT promoter methylation was found in male nonsmokers followed by male smokers and female nonsmokers. This may be a partial explanation for the reason why male nonsmokers had a higher p53 mutation occurrence than female nonsmokers.ConclusionsMGMT promoter methylation may associate with increased occurrence of p53 mutation including the G:C→A:T transition and other p53 mutation patterns in lung cancer, especially among male nonsmokers.

A polymorphic -844T/C in FasL promoter predicts survival and relapse in non-small cell lung cancer

Purpose:Fas ligand (FasL) −844T/C polymorphism (rs763110) has a demonstrated association with lung cancer risk. FasL −844CC with higher FasL expression has been suggested to contribute to tumor progression via immune escape. However, the impact of FasL −844T/C polymorphism on the clinical outcome of non–small cell lung cancer (NSCLC) remains to be identified. Experimental Design: A total of 385 adjacent normal lung tissues from patients with NSCLC were collected to determine FasL −844T/C polymorphism by PCR-based restriction fragment length polymorphism. FasL mRNA and protein expression in lung tumors were evaluated by real-time PCR and immunohistochemistry. The prognostic value of FasL −844T/C polymorphism on survival and relapse was determined by Kaplan–Meier analysis and Cox proportional hazards models. Results: The FasL −844CC genotype had higher prevalence in those with advanced tumors than in those with early tumors (P = 0.008). In addition, patients with the FasL −844CC genotype were more prone to tumor relapse than those with the FasL −844TT+TC genotype (62.1% vs. 37.9%, P = 0.001). Multivariate Cox regression analysis showed that patients with the FasL −844CC genotype had poorer survival in terms of overall survival (OS) and relapse-free survival (RFS) than those with the FasL −844TT+TC genotype (24.1 vs. 42.8 months for OS, HR = 1.455, P = 0.004; 15.4 vs. 31.4 months for RFS, HR = 1.710, P < 0.001). Conclusions:FasL −844T/C polymorphism may predict survival and relapse in NSCLC. We suggest that FasL may be a molecular target for immunotherapeutic interventions to improve the clinical outcome of patients with NSCLC. This finding should be validated by another investigative group. Clin Cancer Res; 17(18); 5991–9. ©2011 AACR.

Effect of TIMP-1 and MMP in Pterygium Invasion

PURPOSE. The migration and invasion of tumor cells correlate with the interaction between MMP and TIMP. Therefore, the purpose of this study was to determine the role of MMP-9, MMP-10, and TIMPs in pterygium formation and progression. METHODS. MMP-9, MMP-10, and TIMP proteins were studied using immunohistochemistry on 82 pterygial specimens and 30 normal conjunctivas. Pterygium epithelial cells (PECs), cultured in a serum-free culture medium, and siRNA were used to knock down TIMP gene expression to understand the role of TIMP in pterygium invasion. RESULTS. Among the 82 pterygial samples, 29 specimens (35.4%) were positive for MMP-9 expression, 28 were positive for MMP-10 (34.1%), and 59 were positive for TIMP1 (72.0%). Staining for MMPs was limited to the cytoplasm of the epithelial layer. The TIMP staining was detected in the pterygium epithelium, fibroblasts and corneal epithelium. In the cell model, cell invasion and migration ability increased in TIMP knockdown PECs compared with the parental control. CONCLUSIONS. MMP-9 and MMP-10 may each play a role in pterygium formation, and TIMPs may contribute to pterygium invasion inhibition.

Gender difference in the prognostic role of interleukin 6 in oral squamous cell carcinoma.

Background Interleukin 6 (IL6) plays an important role in immunoregulation and tumorigenesis in human cancers. Oral squamous cell carcinoma (OSCC) is a malignant tumor of the oral cavity with a male predominant tendency and a poor clinical prognosis. Due to the relatively few cases in females, the gender difference of prognostic markers for OSCC is seldom discussed. Methods In this study, we used immunohistochemical staining methods to investigate the associations between IL6 expression and the clinicopathological characteristics of OSCC. In addition, we collected 74 female and 263 male OSCC patients for evaluation. Results High IL6 expression in tumor cells was significantly associated OSCC patient characteristics including female gender (P<0.001), high lymph node metastatic rate (P = 0.007), and poor tumor differentiation (P = 0.008). Tumor-expressed IL6 had prognostic role in male OSCC patients as defined by the log-rank test (P = 0.014), but not in female patients (P = 0.959). In male OSCC patients, high IL6 expression in tumor cells was associated with poor prognosis (P = 0.025) and a 1.454-fold higher death risk, as determined by Cox regression. Conclusions High IL6 expression in tumor cells was therefore significantly associated with aggressive clinical manifestations and might be an independent survival predictor, particularly in male OSCC patients.

Differential impact of IL-10 expression on survival and relapse between HPV16-positive and -negative oral squamous cell carcinomas.

Human papillomavirus (HPV) is a risk factor in a subset of oropharyngeal cancer; however, the contribution of HPV in the malignancy of oral squamous cell carcinomas (OSCC) is not fully understood in Taiwanese. Herein, 61 patients with no risk factors and 117 patients with one or more risk factors were enrolled in this study. HPV16/18 infection rate in non-smokers, non-drinkers and non-betel quid chewers was higher than their counterparts. The development of HPV-infected cancer has been shown to be associated with interleukin-10 (IL-10) expression. To this end, IL-10 mRNA expression in OSCC tumors was evaluated by real-time RT-PCR. Data showed that HPV-positive patients had higher IL-10 mRNA levels than in HPV-negative patients. Kaplan-Meier and Cox-regression analysis indicated that the prognostic significance of IL-10 mRNA on overall survival and relapse free survival was only observed in HPV-positive OSCC, but not in HPV-negative OSCC. Mechanistically, the elevation of IL-10 by E6 was responsible for increased colony formation and migration capability in OSCC cells. Therefore, we suggest that IL-10 induced by E6 promotes cell growth and migration capability and consequent poor survival and relapse in HPV-positive OSCC.

p53 Dysfunction by Xeroderma Pigmentosum Group C Defects Enhance Lung Adenocarcinoma Metastasis via Increased Mmp1 Expression

Xeroderma pigmentosum group C (XPC) interacts with hHR23B to recognize DNA damage in global genomic repair. We previously showed that XPC is predominantly affected by its hypermethylation and is associated with an increased occurrence of p53 mutation in lung cancer. Tumors with low XPC mRNA levels had a poorer prognosis than those with high XPC mRNA levels, suggesting that XPC defects may enhance tumor metastasis. However, the underlying mechanism is unclear. Here, we show that p53 transcriptional activity is modulated by XPC, whereby XPC stabilizes hHR23B to form an hHR23B-p53 complex that prevents p53 degradation. In addition, in lung cancer cells and xenograft tumors in nude mice, overexpression of XPC suppresses cell/tumor metastatic ability via repression of matrix metalloproteinase-1 (MMP1) transcription by p53. Among tumors from lung cancer patients, those with low XPC mRNA also tended to have low expression of MMP1 mRNA compared with those with high XPC mRNA. Patients with low XPC mRNA levels also more commonly had tumors with late-stage, distant metastasis (M1), nodal metastasis, and T value (P < 0.001 for tumor stage, distant metastasis, and nodal metastasis; P = 0.006 for t value). In conclusion, p53 dysfunction caused by XPC defects in lung cancers may enhance tumor metastasis via increased MMP1 expression.

Cortactin overexpression in the esophageal squamous cell carcinoma and its involvement in the carcinogenesis

The aim of this study is to examine whether dysregulated expression of cortactin occurs in esophageal squamous cell carcinoma (ESCC) and is involved in the development of ESCCs. An immunohistochemistry study for cortactin expression was performed on 46 pairs of surgically resected non-tumor and ESCC tumor tissues and murine tumors of esophagi induced by a carcinogen. The results show increased cortactin expression in 20 and in 22 to a lesser extent, out of a total 46 ESCC tumor tissues. Increased cortactin was also detected in the premalignant lesions, the early stage dysplasia and carcinoma in situ, of ESCC tumor tissues. Differential polymerase chain reaction results showed slight increases in the EMS1 gene only in two of 10 ESCC tumor tissues, suggesting that EMS1 gene amplification is not the only mechanism for cortactin overexpression. In the mouse model induced by treatment with 4-nitroquinoline 1-oxide and arecoline, increased cortactin was detected in the epithelia with hyperkeratosis, papillomas, and ESCCs with invasion into the submucosa, respectively. Overall, we observed cortactin overexpression in early and late stages of human ESCCs and carcinogen-induced murine ESCCs, suggesting a role for cortactin in esophageal carcinogenesis.

Upregulation of microRNA-4417 and Its Target Genes Contribute to Nickel Chloride-promoted Lung Epithelial Cell Fibrogenesis and Tumorigenesis

Nickel compounds have been classified as carcinogens and shown to be associated with induction of epithelial-mesenchymal transition (EMT) in fibrogenesis and tumorigenesis, as well as the crucial role of microRNAs (miRNAs) and their related genes in controlling EMT and cancer metastasis. Thus, the mechanisms involved in the regulation of EMT in nickel-treated cells are of potential interest in understanding lung fibrosis and tumor progression. We investigated the miRNA-dependent mechanisms involved in nickel-induced EMT in lung epithelial cells. Nickel increased miR-4417 expression and decreased its target gene TAB2 expression. Treatment of cells with TGF-β inhibitor SB525334 significantly blocked NiCl2 and TGF-β-induced EMT. The expression of miR-4417 was abolished by SB525334 in TGF-β-treated cells, but not in nickel-treated cells. Both overexpression of miR-4417 and silencing of TAB2 induced fibronectin expression, but did not reduce E-cadherin expression. Moreover, oral administration of nickel promoted lung tumor growth in nude mice that had received BEAS-2B transformed cells by intravenous injection. The induction of EMT by nickel is mediated through multiple pathways. Induction of abundant miR-4417 and reduction of TAB2 expression following nickel exposure and may be involved in nickel-induced fibronectin. These findings provide novel insight into the roles of nickel in fibrogenesis and tumor progression.

BPDE-like DNA adduct level in oral tissue may act as a risk biomarker of oral cancer.

OBJECTIVE Most reports have shown that PAH-related DNA adducts are positively correlated with the smoking status of oral cancer patients. However, these reports did not focus on a specific carcinogen in cigarette smoke. The purpose of this study was to elucidate the role of the BPDE (7,8-dihydroxy-anti-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene)-DNA adduct in the development of oral cancer in Taiwanese patients. DESIGN We enrolled 158 oral cancer patients and 64 non-cancer controls to investigate whether there were differences in susceptibility to cigarette smoke exposure in the formation of DNA adducts between cancer patients and controls. Immunohistochemistry and ELISA (enzyme-linked immunosorbent assay) were used to evaluate BPDE-DNA adduct levels in this study. RESULTS Our data showed that the BPDE-DNA adduct levels were positively correlated with gender, smoking status, betel nut chewing and alcohol consumption. The difference in DNA adduct levels could be explained by genetic polymorphisms of glutathione S-transferase M1 (GSTM1), but not by cytochrome P-4501A1 (CYP1A1). Patients with high DNA adduct levels (≧34.03 adducts/10(8) nucleotides) had an approximately 9.936-fold risk of oral cancer compared with those with low DNA adduct levels (<34.03 adducts/10(8) nucleotides) (p<0.001). CONCLUSIONS We suggest that genetic background and carcinogen exposure may increase the risk of developing oral cancer.