The Influence Of HIF-1α And Microvessel Density As Well As Apoptosis Associated Index On The Prognosis Of Pancreatic Adenocarcinoma

BACKGROUND Hypoxia and gene mutation of the tumor cells can lead to over-expression and stabilization of HIF-1α, HIF-1α and HIF-1β combine with each other in the nucleus to form HIF-1 that subsequently transactivates the genes which play an important role on angiogenesis, glycose metabolism and metastasis. Several studies have already confirmed that hypoxia existed inside pancreatic cancer tissue and many human pancreatic cancer cell lines have HIF-1α expression. AIM Immunohistochemistry, RT-PCR and Western blot analysis are applied to detect the expression of HIF-1α as well as the proteins associated with microvessel density, apoptosis and proliferation, to evaluate the correlation between HIF-1α and the proteins related with tumor angiogenesis, cell proliferation or apoptosis and its clinical significance.MATERIALS AND METHODS 1. Tumor samples are obtained from 41 patients with primary pancreatic carcinoma who underwent surgical resection during the time between April 1993 and February 2003 in general surgery department of our hospital, and 20 cases of normal pancreatic tissue. Immunohistochemistry was used to explore the expression of HIF-1α, VEGF, CD34, Bcl-Xl, p53, CyclinDl, Ki67, Glut-1 in the tissues mentioned above. CD34 was taken as the marker to calculate the microvessel density (MVD) and In situ cell death detection kit (AP) was used to detect cell death of the sections. Then the correlation between the expression of HIF-1α and the proteins/indexes which are associated with tumor angiogenesis, cell proliferation and apoptosis was respectively analyzed, and the relationship between the expression of the proteins and clinical characteristics of pancreatic cancer as well as its significance were investigated. 2. 21 samples of pancreatic carcinoma tissue which obtained from the resectable patients during the time between June 2002 and January 2005 and 10cases of normal pancreas tissue are subjected to our study, RT-PCR and Western blot analysis were used to detect the mRNA and protein expression of HIF-la, VEGF and Bcl-XLin the cancerous and normal tissue.RESULTS 1. The positive expression rate of HIF-la, VEGF, BcI-Xl, P53, CyclinDl and Glut-1 was 63.4%, 75.6%, 87.8%, 46.3% and 68.3% respectively, however none of the normal pancreas (the exocrine portion) showed positive staining of HIF-la, VEGF, P53, CyclinDl and Glut-1 proteins and merely 6 cases (30%) exhibited BcI-Xl positive expression. Mean MVD calculation of pancreatic caner tissue was (33.85±17.69), which was much higher than that of normal tissue (11.95±3.90). Mean apoptotic index of the pancreatic cancer tissues was (1.50+0.69) %, and mean proliferative index was (28.84±18.98) %. 2. The correlation between expression of HIF-la and associated proteins: the expression of HIF-la was positive correlated with VEGF, BcI-Xl and Glut-1 expression, but was not with CyclinDlor p53 expression. MVD calculation was related with HIF-la expression. HIF-la or BcI-Xl positive group of pancreatic cancer tissue had a lower apoptotic index than the negative group, and the proliferative index of the HIF-la or Glut-1 positive group was higher than that of negative group. 3. The relationship between HIF-la or correlated proteins with clinical pathological characteristics: HIF-la and Glut-1 was associated with tumor size, pathological stage and lymphnode metastasis. VEGF correlated with tumor size and pathological stage. p53 related with pathological stage. CyclinDl was associated with lymphnode metastasis. 4. Among the 21 cases of pancreatic cancer tissue, 15 cases showed positive mRNA expression of HIF-la, VEGF 16 cases and BcI-Xl 17 cases. On the contrary, none of the normal tissue was verified positive HIF-la, VEGF or BcI-Xl mRNA expression. In terms of protein expression, 15 cases were confirmed to be HIF-la positive, 16 cases were VEGF positive and 18 cases were BcI-Xl positive among the cancer tissues, however HIF-la and VEGF were both negative in the normal counterparts, among which only 2 cases showed BcI-Xl positive.CONLUSION 1. The expression of HIF-la, VEGF, BcI-Xl, p53, CyclinDl and Glut-1 are strong in pancreatic cancer tissue. 2. HIF-la may promote angiogenensisof pancreatic cancer via up-regurating VEGF expression. 3. HIF-la inhibits cell apoptosis of pancreatic cancer cell probably through up-regulating BcI-Xl. 4. HIF-la possibly up-regulates Glut-1 expression and plays an essential role in tumor progression. 5. The expression of HIF-la is associated with the tumor size, pathological stage and lymphnode metastasis. The expression of HIF-la and certain proteins indicates poor prognosis of the patients.