The RECQ1 Helicase Is Highly Expressed Associated With PCNA In Human Gliomas

Objective:Gliomas have the highest occurrence rate among primary tumors of the central nervous system affecting humans. In spite of comprehensive management which includes operation, radiation therapy and chemotherapy, the prognosis of patients with high-grade glioma remains poor. According to the reports, the median survival time of patients with glioma of WHO grade III glioblastoma (WHO IV) are both very low. Therefore, new therapeutic approaches that based on a better understanding of the mechanisms of malignant glioma genesis and development are urgently needed. Identification of several biomarkers that are differentially expressed between the high grade gliomas and the lowgrade tumors or normal brain tissues is important to elucidate the critical mole-cular events of thetumors, to accurately predict the patient prognosis and to identify the most suitable pathways to target using novel therapeutic agents.RecQ helicases are a ubiquitous family of DNA unwinding enzymes involved in the maintenance of chromosome stability. In order to determine RecQ1 whether it can be used for the degree of malignancy in human glioma and prognostic indicators, feasibility theoretical basis for gene therapy of gliomas. As an indicator of cell proliferation, we used the proliferation cell nuclear antigen (PCNA) expression index.In the present study, the level of RECQ1 mRNA and the protein were measured by RT-PCR and immunohistochemistry separately both in primary human glioma samples of different grades and normal brain tissues. Besides, the association of patient prognosis with PCNA expression was also determined. Our results suggest that RecQl is an intrinsic regulator of the gliomagenesis and may be used as a potential target and predictor of survival in gliomas. However, the mechanism that is responsible for RecQ1 in tumorigenesis and the biological functions merit further evaluation.Methods:1 Tumor specimens and patients clinicopathological characteristicsA total of 83 cases with glioma were admitted to the neurosurgical department for operation at the Second Hospital of Hebei Medical University and the first hospital of BAODING between 2012 Nov and 2013 Dec. Patient characteristics were collected before initial surgery. In 83 patients, including male 47 cases, female 36 cases, in which low grade gliomas (WHO grade 1-2) in 39 cases of high grade gliomas (WHO grade 3-4) in 44 cases. The tumors located in the hemisphere in 74 cases,4 cases of cerebellum,3 cases of thalamus,1 cases of the third ventricle,1 cases of brain stem.80 case of single and multiple in 3 cases.None of the patients received any management such as chemotherapy or radiation before the operation. Thirteen normal brain tissue samples were from consenting individuals who died of traffic accidents. These samples were identified as normal by special tissue staining and light microcopy. These tissues were divided into two parallel subgroups randomly:one subgroup was frozened and stored at -80℃ before RNA and protein were extracted, and the other was formalin-fixed. All tumor samples was diagnosed by two or more experienced neuropathologists from the department of pathology of the same hospital to identify character and degree.2 The expression of RecQ1 was detected by immunohistochemistry.The expression of RecQ1 was examined by immunohistochemistry in primary human glioma samples of different grades and normal brain tissues. 3 The relationship between RecQl expression pattern and various clinicopat hological characteristics of patients including age, sex, tumor pathological grade and PCNA expression at the time of surgery is recorded.4 The expression of RecQ1 mRNA in glioma samples and normal brain tissues.The expression of RecQ1 mRNA were examined using RT-PCR in primary human glioma samples of different grades and normal brain tissues.Results:1 Immunostaining analysis manifested that RecQl protein was localized to the cytoplasm and nucleus of glioma cells and was highly expressed. The frequency of RecQl-positive specimens was 56.6%(47/83). The frequency of RecQl-positive were 72.9%(35/48) and 34.3% (12/35) in high-grade glioma and low-grade ones, respectely. In 18 normal brain tissues, the expression of RecQl was not detected. In addition, gliomas of different grades exhibited mild to strong RecQ1 expression.2 Immunostaining analysis showed that PCNA protein was localized in the cytoplasm.75 specimens was PCNA-positive of all the 83 glioma samples (80.7%) that were examined. However, no PCNA-positive cells were observed in normal brain tissues. The percentage of PCNA-positive cells had a positive correlation with increasing glioma grades (P<0.05).3 RecQl mRNA in gliomas tissues of different grades and normal brain tissues was examined by RT-PCR. The mRNA expression in gliomas was displayed. The normalized mRNA expression of RecQ1 was 0.37±0.02,1.05±0.08 and 2.22±0.14 for normal brain tissues, low- and high-grade gliomas, respectively. RecQ1 mRNA expression was increased significantly in glioma samples compared to that in the normal brain tissues (P<0.05).Conclusions:1 We demonstrate that RecQ1 is overexpressed in gliomas and the expression is increased with ascending tumor grades.2 The level of RecQl mRNA is amplified in different grades of glioma tissues. Expression of RecQ1 mRNA were higher in the high-grade glioma than in the low-grade ones. Expression of RecQl mRNA were few in the normal brain tissues.3 The PCNA index is higher in the RecQl-positive group than in the RecQl-negative group. Positive correlation between RecQ1 and PCNA expression is shown in the glioma tissues. The association of the RecQ1 expression with the glioma pathological grade and PCNA expression is positive and significant. No significant correlation is found between RecQl expression and age or gender.