Study On Expression Of Annexin A5 In Sporadic Colorectal Cancer And Its Relation With Tumor Stage And Prognosis In Colorectal Cancer

Carcinoma of the colon and rectum is one of the most common alimentary malignancies in developed nations, and cancer mortality among the first places 2,3. Even in developing countries, morbidity is with a increasing trend. Now, CRC has become one of malignancies with the fastest rising incidence in most parts of China. In Shanghai, 2002, colorectal cancer incidence has gone beyond the first two ranks, second only to lung cancer. Today , operation is the most important treatment of CRC, supported by chemotherapy, radiotherapy or immunotherapy, as well as traditional Chinese medicine treatment. However, colorectal cancer after 5 years the relapse rate, mortality still remains at a higher level. To take positive measures for early detection and effective treatment has become the common goal for medical workers. So looking for new tumor markers for early diagnosis of colorectal cancer and new protein for therapeutic targets is a hot spots for basic and clinical research of CRC.This study we are concerned is one important member of annexin A family ---Annexin A5. The annexins are characterized as a family of proteins capable of binding to acidic phospholipids in a Ca2+-dependent manner and they appear to be widely distributed throughout nature. Up to this day, there are total of twelve annexins have been found in higher vertebrates and form the A family of the annexins. In most biological contexts studied, the annexins are highly abundant proteins, reaching the level as high as 0.5% to 2% of the total cellular proteins and all these proteins present a homologous core structure and a highly variable N-terminus. Based on their Ca2+-dependent interaction with phospholipids and membranes, many physiological functions have been described for the annexins including endocytosis, exocytosis, cell-cell or cell-matrix interaction, formation of ion channels, inhibition of phospholipase A2 and so on. Unfortunately, there has not been a definitive description of any physiological role played by these annexins in more than 20 years of study. Although any exact in physiological function has not been described for the annexins, there are great deals of evidence to suggest that they are involved in the pathogenesis of many different cancers. In many cancers, there is sharp up-regulation of annexins in both mRNA and protein levels. On the other hand, there is data indicating that down-regulation of annexins may play a significant role in tumorigenesis and metastasis of other types of cancer. However, the precise role played by the annexins in the pathogenesis of tumor is still unknown. Related studies have shown that expression of some members of annexin A family has changed in the colorectal cancer tissues with different characteristics. That means these members have been playing important roles in the occurrence and the development process of colorectal cancer. Nevertheless, no strong evidences had shown they had affected incidence of colorectal cancer, even different researchers had conflicting results.Therefore, in our opinion, it is necessary to analyze the expression of A family members in colorectal cancer and their mechanism in tumorigenesis.Above all, we succeeded in cloning full length sequence of human annexin A5 coding regions of from human placenta by RT-PCR. Then we constructed and identified recombinant eukaryotic expression vectors of annexin A5.51 tumor samples with complete clinical data were selected. At the same time 51 normal tissues (obtained from patients with benign colorectal diseases) were chosen as normal control. We firstly detected p53 and Ki-67 in tumor tissues by immunoassaying and split all tumor samples into two groups separately according to the detection of p53 or Ki-67. Then the mRNA and protein levels of annexin A5 in each sample were analyzed by real-time quantitative PCR and immunohistochemistry. We found that there is an up-regulation of annexin A5 in colorectal cancer. We also found the up-regulation has a positive correlation with the mutation of p53 or Labeling Index (Ki-67) in tumor tissues. Besides, the mutation of p53 in tumor tissues has a negative correlation with Labeling Index (Ki-67). Our study indicates that annexin A5 might be used as an assistant clinicopathological biomarker in cancer diagnosis and the up-regulation of annexin A5 in colorectal cancer might be related to the malignant proliferation of tumor cells.We investigated the expression of ANXA5 in colorectal adenocarcinoma. This study included 176 consecutive patients with sporadic colorectal cancer. Paired colorectal tissue samples and corresponding nonmalignant tissues were obtained by surgical resection. ANXA5 mRNA and protein expression in each tissue were assessed by real-time RT-PCR and immunohistochemical staining. Real-time RT-PCR showed that there is an up-regulation in mRNA level of ANXA5 in tumors . Immunohistochemical study revealed that high ANXA5 expression was present in 40.58% of tumors. Data were statistically correlated with pathological parameters and clinical outcome. In this study, we have shown that expression of ANXA5 can be used as a potential molecular marker to predict patient outcome in patients treated with surgical resection alone. Our data showed that high ANXA5 expression has a strong correlation with decreased five-year survival and increased tumor recurrence both in univariate and multivariate analyses. Multivariate analysis indicated that ANXA5 expression is an independent prognostic factor for poor survival. Thus, tumor levels of ANXA5 regardless of tumor stage can be used to determine patient outcome. In addition, ANXA5 expression level can potentially be used as a prognostic factor before surgery can be done. Our findings also suggest that ANXA5 plays an important role in tumor growth, progression, and metastasis in colorectal adenocarcinoma.We selected two human colon adenocarcinoma cell lines and analyzed their metastatic potentials by invasion/migration assay (higher metastatic potential: SW620; lower metastatic potential:SW480). Then we analyzed expression of annexin A1, A2 and A5 mRNA and protein levels in cell lines by real-time PCR and western blot. We found that the order of A1, A2, A5 expression level from high to low was separately SW620 >SW480, SW480 > SW620, and SW480≥SW620. Our results indicated that annexin A1 and A2 may play important roles in tumor metastasis and annexin A5 may not work in metastasis but apoptosis. We also imagine that different annexins may be complementary in functionWe analyzed expression of annexin A5 in spocitic colorectal cancer and its mechnium in tumorigenesis. We determined its prognostic significance by correlating ANXA5 expression with tumor stage and clinicopathologic features.Our work would make the groundwork for further researches on physiological functions of the annexins and their role in tumorigenesis.