Zhi Gang Liu

Prognostic significance and therapeutic implications of centromere protein F expression in human nasopharyngeal carcinoma

BackgroundOur recent cDNA microarray data showed that centromere protein F (CENP-F) is significantly upregulated in primary cultured nasopharyngeal carcinoma (NPC) tumor cells compared with normal nasopharyngeal epithelial cells. The goal of this study was to further investigate the levels of CENP-F expression in NPC cell lines and tissues to clarify the clinical significance of CENP-F expression in NPC as well as the potential therapeutic implications of CENP-F expression.MethodsReal-time RT-PCR and western blotting were used to examine CENP-F expression levels in normal primary nasopharyngeal epithelial cells (NPEC), immortalized nasopharyngeal epithelial cells and NPC cell lines. Levels of CENP-F mRNA were determined by real-time RT-PCR in 23 freshly frozen nasopharyngeal biopsy tissues, and CENP-F protein levels were detected by immunohistochemistry in paraffin sections of 202 archival NPC tissues. Statistical analyses were applied to test for prognostic associations. The cytotoxicities of CENP-F potential target chemicals, zoledronic acid (ZOL) and FTI-277 alone, or in combination with cisplatin, in NPC cells were determined by the MTT assay.ResultsThe levels of CENP-F mRNA and protein were higher in NPC cell lines than in normal and immortalized NPECs. CENP-F mRNA level was upregulated in nasopharyngeal carcinoma biopsy tissues compared with noncancerous tissues. By immunohistochemical analysis, CENP-F was highly expressed in 98 (48.5%) of 202 NPC tissues. Statistical analysis showed that high expression of CENP-F was positively correlated with T classification (P < 0.001), clinical stage (P < 0.001), skull-base invasion (P < 0.001) and distant metastasis (P = 0.012) inversely correlated with the overall survival time in NPC patients. Multivariate analysis showed that CENP-F expression was an independent prognostic indicator for the survival of the patient. Moreover, we found that ZOL or FTI-277 could significantly enhance the chemotherapeutic sensitivity of NPC cell lines (HONE1 and 6-10B) with high CENP-F expression to cisplatin, although ZOL or FTI-277 alone only exhibited a minor inhibitory effect to NPC cells.ConclusionOur data suggest that CENP-F protein is a valuable marker of NPC progression, and CENP-F expression is associated with poor overall survival of patients. In addition, our data indicate a potential benefit of combining ZOL or FTI-277 with cisplatin in NPC suggesting that CENP-F expression may have therapeutic implications.

Increased pretreatment levels of serum LDH and ALP as poor prognostic factors for nasopharyngeal carcinoma

Serum enzymes that play potential roles in tumor growth have recently been reported to have prognostic relevance in a diverse array of tumors. However, prognosis-related serum enzymes are rarely reported for nasopharyngeal carcinoma (NPC). To clarify whether the level of serum enzymes is linked to the prognosis of NPC, we reviewed the pretreatment data of lactate dehydrogenase (LDH), alkaline phosphatase (ALP), and glutamyl transferase (GGT) in 533 newly diagnosed NPC patients who underwent radical radiotherapy between May 2002 and October 2003 at Sun Yat-sen University Cancer Center. Patients were grouped according to the upper limit of normal values of LDH, ALP, and GGT. The Kaplan-Meier method and log-rank test were used for selecting prognostic factors from clinical characteristics and serum enzymes, and the Chi-square test was applied to analyze the relationships of clinical characteristics and serum enzymes. Finally, a Cox proportional hazards model was used to identify the independent prognostic factors. We found that increased levels of LDH had poor effects on both overall survival and distant metastasis-free survival (P = 0.009 and 0.035, respectively), and increased pretreatment level of serum ALP had poor effects on both overall survival and local recurrence-free survival (P = 0.037 and 0.039, respectively). In multivariate analysis, increased LDH level was identified as an independent prognostic factor for overall survival. Therefore, we conclude that increased pretreatment serum LDH and ALP levels are poor prognostic factors for NPC.

Haemoglobin, Neutrophil to Lymphocyte Ratio and Platelet Count Improve Prognosis Prediction of the TNM Staging System in Nasopharyngeal Carcinoma: Development and Validation in 3237 Patients from a Single Institution

AIMS To improve prediction efficiency by incorporating complete blood count (CBC) into the TNM system on 5 year disease-specific survival (DSS) for patients with nasopharyngeal carcinoma (NPC). MATERIALS AND METHODS The CBC of 3237 patients undergoing radiotherapy was retrospectively evaluated. In total, 2820 patients treated with non-intensity-modulated radiotherapy (IMRT) were randomly divided into development (1895 patients) and validation cohorts (925 patients). The association of potential risk factors with 5 year DSS was tested by Cox proportional hazards analysis and a prognostic index was created by assigning weighted scores proportional to a regression coefficient to each factor. Each cohort was divided into low, intermediate and high prognostic index. The prognostic index was validated in the validation cohort and compared with the TNM system on prediction of 5 year DSS. Validation was repeated in another independent group of 417 patients treated with IMRT. RESULTS Eight independent prognostic factors were identified: gender, age, T or N stages, anaemia or thrombocytosis during radiotherapy, continuous reduction in haemoglobin, high neutrophil-lymphocyte ratio before radiotherapy. Each was assigned a number of points. The area under curve (AUC) of the prognostic index was larger than that of Union Internationale Contre le Cancer/American Joint Cancer Committee TNM system 2009 (0.697 versus 0.619, P < 0.001). CONCLUSION A CBC-based prognostic index was developed and had a higher prediction efficiency on 5 year DSS in NPC than the TNM system alone.

Influence of pretreatment ideal body weight percentile and albumin on prognosis of nasopharyngeal carcinoma: Long-term outcomes of 512 patients from a single institution.

The purpose of this study was to investigate the relationship between pretreatment nutritional status and prognosis of nasopharyngeal carcinoma (NPC).

Bmi-1 induces radioresistance in MCF-7 mammary carcinoma cells

Bmi-1, a member of the polycomb family, it is involved in self renewal of stem cells and functions as an oncogene in many malignant human cancer types. Recent studies have demonstrated that Bmi-1 is a predictive factor for poor patient prognosis. However, the underlying mechanisms of radioresistance mediated by Bmi-1 are poorly understood. In this study, the dose-survival relationship was analyzed using a clonogenic survival assay and combined radiation treatment with Bmi-1 overexpression or silencing. DNA double-strand break (DSB) and repair was assessed by immunofluorescence staining of γH2AX foci. In addition, mitochondrial membrane potential was detected between Bmi-1 knockdown and control MCF-7 cells after irradiation. Apoptosis and cell cycle were evaluated by flow cytometry. We found that exposure of MCF-7 cells overexpressing Bmi-1 to ionizing radiation resulted in dramatically enhanced survival relative to control cells, whereas cells with silenced Bmi-1 showed markedly reduced survival. Bmi-1 inhibition significantly increased DSBs and decreased DSB repair. Furthermore, Bmi-1 knockdown induced loss of mitochondrial membrane potential and enhanced apoptosis by up-regulating p53, p21, Bax expression and down-regulating p-AKT and Bcl-2 expression. These results indicate that Bmi-1 may play an important role in radiosensitivity, and the suppression of its expression might be a potential therapeutic target for breast cancer.

Identifying FGA peptides as nasopharyngeal carcinoma‐associated biomarkers by magnetic beads

Early diagnosis and treatment is known to improve prognosis for nasopharyngeal carcinoma (NPC). The study determined the specific peptide profiles by comparing the serum differences between NPC patients and healthy controls, and provided the basis for the diagnostic model and identification of specific biomarkers of NPC. Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOF‐MS) can be used to detect the molecular mass of peptides. Mass spectra of peptides were generated after extracting and purification of 40 NPC samples in the training set, 21 in the single center validation set and 99 in the multicenter validation set using weak cationic‐exchanger magnetic beads. The spectra were analyzed statistically using FlexAnalysis™ and ClinProt™ bioinformatics software. The four most significant peaks were selected out to train a genetic algorithm model to diagnose NPC. The diagnostic sensitivity and specificity were 100% and 100% in the training set, 90.5% and 88.9% in the single center validation set, 91.9% and 83.3% in the multicenter validation set, and the false positive rate (FPR) and false negative rate (FNR) were obviously lower in the NPC group (FPR, 16.7%; FNR, 8.1%) than in the other cancer group (FPR, 39%; FNR, 61%), respectively. So, the diagnostic model including four peptides can be suitable for NPC but not for other cancers. FGA peptide fragments identified may serve as tumor‐associated biomarkers for NPC. J. Cell. Biochem. 113: 2268–2278, 2012.

Relationship between methylation status of ERCC1 promoter and radiosensitivity in glioma cell lines

Ionizing radiation represents one of the most important therapies for glioma, a lethal primary brain tumor, while radiotherapy remains a challenge for radiation oncologist because of radioresistance. Radiosensitivity of gliomas determines radiotherapy efficacy. Evidence demonstrated that methylation of CpG Island in the promoter region may result in gene silencing. This study was designed to determine the relationship between methylation status of ERCC1 promoter region and radiosensitivity in glioma cell lines. We investigated the expression levels of ERCC1 transcripts and protein in GBM cell lines. Colony forming experiments was used to measure surviving fraction at 2 Gy (SF2) in four human glioma cell lines, MGR1, MGR2, SF767 and T98G. Methylation status in the promoter region of ERCC1 in these glioma cell lines was determined by using bisulphate sequencing and MSP analysis. Radiosensitivity was examined to be heterogeneous in these glioma cell lines. There was a statistical difference in the radiosensitivity between glioma cell lines with and without methylation of ERCC1 gene promoter CpG islands. Furthermore, we promoted ERCC1 expression by 5‐azacytidine treatment which resulted in the reduction of radiation‐induced cell killing in radiosensitive cell lines. Our data indicate that methylation status of ERCC1 is associated with radiosensitivity in glioma cell lines. It could be used as a new biomarker for predicting the radiosensitivity of human gliomas.

Establishment and characterization of a novel nasopharyngeal carcinoma cell line (SUNE2) from a Cantonese patient

The undifferentiated form of nasopharyngeal carcinoma (NPC) is the most common malignant head and neck cancer in South China, especially in Cantonese populations. However, few NPC cell lines have been established from the patients in this region. In this study, we established a new NPC cell line, termed SUNE2, from a Cantonese patient with undifferentiated NPC. This cell line had extremely low concentrations of Epstein-Barr virus (EBV) DNA in long-term culture and expressed low levels of latent membrane protein 1 (LMP1), latent membrane protein 2A (LMP2A), BamH1-A right frame 1 (BARF1), EBV-encoded RNA-1 (EBER1), and EBV-encoded RNA-2 (EBER2) in early passages. SUNE2 cells also showed much stronger transforming ability than 5-8F cells in colony formation assays and anchorage-independent growth assays in soft agar, and they only need 2 weeks to form tumors in nude mice. In summary, the SUNE2 cell line is a new in vitro model that can be used for further research on the mechanisms underlying the occurrence and development of NPC.