| PrefacesMany studies have shown that p21 was a cyclin-dependent ki-nase inhibitor ( GDI) , inhibit the cyclin - compound, and plays an important role in the growth, progression, and biology behavior of tumor, may be a new indicator to evaluate malignant level of carcino-ma. Absence of p21 may significant the carcinoma growth quickly, p21 expression have closely associated with the TNM stage, the be-havior of invasion and metastasis of carcinoma. Esophageal carcinoma is more and more threatening the health and life of human. In this study, we examined and analyzed the expression of p21 mRNA in pri-mary esophageal carcinoma by reverse trascription polymerase chain reaction ( RT - PCR) to define the role of p21 in this kind of cancer.Materials and MethodsEsophageal carcinoma tissues and surrounding esophageal tissues from patients who received surgery at the First Affilated Hospital of China Medical University and the Liao Ning Tumor Hospital between 2001 January to October . The tissues were frozen at - 80℃. The pa-tients had no detectable metastases in distant organs at the time of sur-gery. No patient had received chemotherapy or radiation therapy be-fore surgery.1. Extraction of total RNA; Total RNA was extracted from tissue samples using a RNA extraction reagent, Trizol reagent(GIBCOBRL, Int). The concentration of total RNA was adjusted to l|xg/|xl.2. Reverse Transcription ( RT) ;2μJ of total RNA were incubated in 12μl of reaction buffer.3. Polymerase Chain Reaction ( PCR ) : PCR primers ( Sangon, China) for p21cDNA according to the p21 gene structure. The PCR reaceion was carried out in three steps as follows; 95℃ for 2min(l cycle) ; 94℃ for Imin; 55℃ for Imin; 72℃ for 1.5min(28 cycle) ; and 72℃ for7min(l cycle)4. PCR fragments were analyzed by electrophoresis on 12% poly-acrylamide gels, and DNA was visualized by ethidium bromide stai-ning.Results1. RT -PCR analysis of p21mRNA in esophageal carcinoma and surrounding esophageal carcinoma tissues: in 54 esophageal carcinoma tissues, there were 16(29.6% ) cases expressed p21 mRNA, in sur-rounding esophageal carcinoma tissues, there were 50(92.6% ) cases expressed p21mRNA. Statistical, analysis shows significant difference between the expression of p21mRNA in carcinomas and surrounding e-sophageal carcinoma tissues ( P <0.01).2. p21 expression and tumor progression; in 54 esophageal carci-noma tissues were divided in two groups; one with lymph node metas-tasis; the other without lymph node metastasis. p21 mRNA was more expressed in cases without lymph node metastasis (13/33 39. 4% ) than those with lymph node metastasis (3/21 14.2% ). Statistical a-nalysis shows significant difference between the expression of p21mRNA in without lymph node metastasis and with lymph node me-tastasis ( P < 0. 05 ). Statistical analysis shows significant difference between the expression of p21mRNA in TNM stage I and HI, (P < 0.05) , no significant difference between I and II ( P >0.05) , and II and IH(P>0.05).DisscussionIn this study, p21 high expression in normal surrounding esopha-geal carcinoma tissues than esophageal carcinoma tissues. P21 expres-sion have opposite relation with esophageal carcinoma TNM stage, and p21 low expression in the tissue that with lymph node metastasis, these result imply'; absence expression and lose function of p21 play an important role in esophageal carcinoma happen; the expression of p21 protein may be an reference indictor to determine differentiation level of carcinoma.Conclusion1. p21 was high expression in surrounding esophageal carcinoma tissues than esophageal carcinoma tissues.2. p21 was high expression in without lymph node metastasis group than with lymph node metastasis group.3. The expression of p21 is closely associated with the TNMstage, the behavior of invasion and metastasis of primary esophageal carcinoma.
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