Research On The Expression Level Of Folate Receptor Alpha In Esophageal Carcinoma

ObjectiveThe aim of this experiment was to detect the expression level of folate receptor alpha (FOLR1) in esophageal cancerous tissues, the paired adjacent tissues, the normal esophageal mucosa and EC109 (esophageal carcinoma cell line), to compare their differences of FOLR1 expression level. And analyzing the correlation between FOLR1 expression level and smoking, excessive drinking, bad eating habit, tumor clinical pathological character.MethodsEsophageal cancerous tissues and the paired adjacent tissues in 40 cases were collected after the operation. All the cases were from the First Affiliated Hospital of Medical College, Shantou University (October, 2006 to May, 2007). At the same time, cells of esophageal carcinoma cell line EC109, peripheral blood lymphocyte, 5 cases normal esophageal mucosa were collected as contrast. Detected the FOLR1 expression level in all samples.1) EC109 cells were cultured in folic-free RPMI1640, stained by FA-FITC. Positive cell percentage and fluorescence intensity of EC109 cells were detected by flow cytometry.2) Fresh esophageal carcinoma tissues and the paired adjacent ones were taken just after the operation, made into monoplast suspension and stained by FA-FITC respectively. Positive cell percentage and fluorescence intensity were detected by flow cytometry. All the paired adjacent tissues were taken in 2 cm to 5cm from the edge of the carcinoma.3)Detected FOLR1 protein in esophageal carcinoma tissue, the paired adjacent esophagus tissue and EC109 cells by immunohistochemistry.4)Total RNA of 40 cases carcinoma tissues and the paired adjacent esophagus tissues, 5 cases normal esophageal mucosa, EC109 cells and peripheral blood lymphocyte was abstracted by RNAiso Reagents, reversely transcribed into cDNA and detected FOLR1 expression level by real time polymerase chain reaction.Result1) We only took 10 cases samples to make into monoplast suspension and to stain by FA-FITC respectively. Then detected the samples by flow cytometry. It was showed that FA-FITC positive cells percentage in the monoplast suspension of carcinoma tissues was 0.21(0.37), which was lower than that in the monoplast suspension of the paired adjacent tissues 0.37(0.82). The difference was statistically significant(P=0.038,<0.05). FA-FITC positive cells percentage in EC109 cells was 98.7%.2) Detected esophageal cancerous tissues and the paired adjacent tissues by immunohistochemical method. In the observed 40 cases, 32 cases (80%) showed (-), 8 cases (20%) showed (±) in esophageal carcinoma tissues. Meanwhile, 16 cases (40%) showed FRα(-), 20 cases (50%) showed (±), 4 cases (10%) showed (+) in the paired adjacent tissues. The difference of FRαexpression was significant (P=0.000,<0.01).3) Relatively quantitative analysis by real time RT-PCR: Set the expression level of FOLR1 in peripheral blood lymphocyte was 1.00. The expression level of FOLR1 in cancerous tissues, the paired adjacent tissues, normal esophageal mucosa was 1.03(4.63), 35.66(315.44), 54.15(566.67) respectively. It was suggested that FOLR1 expression level was lowly expressed in cancerous tissues. The difference of FOLR1 expression level in cancerous tissues compared with that in the adjacent tissues and normal esophageal mucosa was statistically significant(P=0.000,<0.01), but the difference of FOLR1 expression level between the paired adjacent tissues and normal esophageal mucosa was not statistically significant(P=0.263,>0.05).4) Relative quantitative analysis by Real time RT-PCR: FOLR1 level of carcinoma tissues was higher in patients with ages≥60 years, tumor diameter≥5cm, full-thickness mucosa invasion and lymph node metastasis than in those ages<60 years, tumor diameter<5cm, superficial invasion and non-lymph node metastasis, but there was no statistically significance(P>0.05). It was found that no correlation between FOLR1 level of carcinoma tissues and gender, tumor pathological type, diseased region (P>0.05). FRαexpression depression in carcinoma tissues was more obvious in the cases ages <60 years compared with those ages≥60 years, and the difference of NFRα(the level of mRNA FRαexpression in carcinoma tissue was represented as N-times the level detected in the paired adjacent tissue) between two groups was statistically significant(P<0.01). No significant correlation between NFRαand diseased region, pathological type, TNM stage, tumor size, depth of invasion ,lymph node metastasis was found(P>0.05).5) It was observed that no significant correlation between FOLR1 expression level and three behavior risk factors (smoking, excessive drinking and eating too hot, too cold or too fast) (P>0.05).6) It was found that no significant correlation between ABO blood type and FOLR1 expression level (P>0.05).Conclusion1) FOLR1 was expressed in cancerous tissues, the paired adjacent mucosa and EC109 in different level and they all had the capability of binding folic acid.2) Detection of FOLR1 expression level in esophageal cancerous tissues and the paired adjacent mucosa was meaningful for judging the extent of disease and guiding surgery treatment.3) The FOLR1 expression level in esophageal carcinoma tissues were not related with age, gender, tumor size, depth of invasion and pathological type.4) Smoking, excessive drinking and eating too hot, too cold or too fast had no influence on the FOLR1 expression level in esophageal carcinoma tissues.5)The FOLR1 expression level in esophageal carcinoma tissues has no relationship with ABO blood types.