The Expression Of CXCR4 Gene In Gastric Carcinoma And Its Clinicopathological Significance

ObjectiveChemokine ( C - X - C motif) receptor 4 ( CXCR4 ) is a chemokine receptor in the G protein - coupled receptors (GPCR) gene family. CXCR4 is seven - transmembrane G protein - coupled receptors for alpha - chemokines. They also function as fusion cofactors for T - cell - tropic HIV - 1 strains. CXCL12 ( Stromal cell - derived factor -1; SDF -1) is the of CXCR4. CXCL12 and its cognate receptor CXCR4 make up of a CXCL12/CXCR4 biological axis. The CXCL12/CXCR4 biological axis is involved in regulating special signal and mediating different effects. Recent evidence has suggested that CXCL12/CXCR4 biological axis not only regulates the assemble of leukocyte but also induces many effects which directly work on stroma and cancer cell. Binding of chemokines to their receptors triggers the activation of signal transduction pathway such as ras/MAPK (mitogen -activated protein kinase) pathway, actin polymerization , cytoskeleton rearrangements, pseudopod formation and the increase of ability of cell migration and invasion. All these suggest that CXCR4 plays a role in neoplasm metastasis. Muller et al. reported that CXCL12/CXCR4 biological axis determined the pattern of breast cancer metastasis. Because CXCR4 also expressed in prostate carcinomas, astrocytomas and chronic lymphocytic leukemia, the reaction of CXCR4 maybe not have been limited in breast cancer.Gastric carcinoma is one of the most common malignant tumors in China. Although implementing gastric carcinoma radical resection, the 5 - year survival rate is still around 50%. The invasion and metastasis are main reasons for poor prognosis of advanced gastric carcinoma. To improve clinical curative effect, the understanding molecular mechanism of neoplasm metastasis is can't be evasivework. And the molecular mechanism of neoplasm metastasis is the base of confirm therapy target.To understand whether and which step CXCR4 influences the generation and the process of gastric carcinoma, in this study, we mensurated the expression of CXCR4 in gastric carcinoma and analyzed the relationship between the expression of CXCR4 and the progression and metastasis of gastric carcinoma. And then evaluated the probability of CXCR4 as a molecular marker of gastric carcinoma progression and a therapy target based on the results above.Materials and methods1. SpecimensAll specimens were obtained from 30 patients (18males and 12 females) with gastric carcinoma who underwent operation at the Department of Oncolozy Surgery (First Teaching Hospital, China Medical University, Shen Yang, P. R. CHINA) between August 2003 and November 2003. None of the patients received neoadjuvant chemotherapy or radiotherapy. Cancer tissue ( wipe off ne-crotissue) and uninvolved normal tissue ( 5 cm away from the edge of cancer tissue ) were collected during operation. Those were frozen in liquid nitrogen for 30 minutes and then stored in -80^ refrigerators. Routinely, the resected specimens were histologically examined by H&E staining according to the general rules of the Japanese Classification of Gastric Carcinoma. The Borrmann gross type, Ming classification of growth pattern, and grade of differentiation were obtained from the operative records and the pathology reports. The pT classification representing the depth of wall invasion and the pN classification representing the extent of regional lymph node metastasis were assessed using the standard criteria of the 5th TNM staging system.2. ReagentsTrizol (BioBasic Inc. Canada) RNA PCR Kit (AMV) Ver. 3.0 (TaKaRa. Dalian) Primers of CXCR4 and B - actin were synthesized by Beijing BGI life Tech Co. Ltd.3. Experimental methodsThe expression of CXCR4 in gastric carcinoma and uninvolved normal tissue were measured by RT - PCR. And then the relationship between CXCR4 and Gastric Carcinoma biology behavior was analyzed. Total RNA was extracted by One - step method. The purification was determined by the spectrophotome-ter. Total RNA had an OD 260/280 ratio of 1. 8 to 2. The RNA was reverse transcripted to cDNA for PCR amplification. The amplified products were elec-trophoresed on 2% agarose gel. Gels were stained with ethidium bromide and photographed. All signals were normalized to the mRNA levels of β- actin , and expressed as a radio.4. Statistical analysisAll data were analyzed by SPSS software. The data are present as mean ± standard deviation ( SD) of the mean; the Student's t test was performed for qualitative data;P value less than 0.05 was considered statistically significant.Result1. The relationship between CXCR4 gene RT - PCR assay of gastric carcinoma and lymphatic metastasis: The expression index of CXCR4 in lymph node metastasis positive group (0.34 ±0. 12) is significantly higher than that in metastasis negative group (0.23 ±0.07) (p<0.05), and the expression indexes of CXCR4 were 0. 26 ±0.04 in gastric carcinoma stage pN₁ and 0. 51 ±0.09 in gastric carcinoma stage pN₂ - pN₃. ( p < 0. 05).2. The expressions of CXCR4 in gastric carcinoma without regional lymph node metastasis and uninvolved normal tissue were not of statistics difference observed in the present study.3. We noted no significant correlation between CXCR4 gene expressions in gastric carcinoma and the Borrmann gross type or depth of invasion or the Ming classification of growth pattern or grade of differentiation in the present study.