Application Of Tumor-associated Proteins In Diagnosis And Treatment Of Colorectal Cancer

At present, colorectal cancer (CRC) is the third most common cause of cancer deaths worldwide. The incidence of CRC in China has increased rapidly during the past few decades, thereby it becomes the focus of our health work, and also the focus of clinical researchers. The detection of tumor markers holds important guiding meaning in the diagnosis and treatment of colorectal cancer, and it has become a common assistant examination meaning in clinic. Detection of CEA, CA199 in serum has been widely used in diagnosis and treatment of colorectal cancer, but their specificity is low, because they belong to the carbohydrate antigen and their expression increased in many other non-gastrointestinal tumors and certain benign digestive diseases. To find tumor markers with high specificity and sensitivity are of great importance in the early diagnosis and early treatment of colorectal cancer. Additionally, in the process of colorectal cancer, tumor metastasis played an important role and became another research focus. The current study confirmed that: as an independent prognostic indicator, the value of micro-metastasis was superior to tumor staging, detection of micro-metastasis indicated high-risk of tumor recurrence. However, there is not yet an effective tumor marker to predict lymph node metastasis in colorectal cancer, therefore, to find such a tumor marker is imperative. Finally, the tumor marker has been widely used as theraputic target for cancer in clinic. For example, curcumin can regulate the level of P53, thereby inhibit the development of tumor, however, the specific therapeutic mechanism is unclear. To clarify its mechanism is of important guiding significance for the treatment of colorectal cancer. This research is just raised on such a background: First, several common used tumor markers of colorectal cancer (CEA, P53, Ki-67 and GST-Ï€) were screened through immunohistochemistry, and the corresponding clinical biological behaviors of tumor were analyzed, and finally the proteins most relevant to the diagnosis, prognosis and recurrence of colorectal cancer was found out. Subsequently, in order to further clarify the metastasis-associated protein of colorectal cancer, the proteome approach was applied to the identification of differential proteins between normal lymph nodes and sentinel lymph node micrometastasis of colorectal cancer. By comparing these two sets of samples of protein electrophoresis, differentially expressed proteins were identified and further analyzed. Finally, the application of tumor markers as a molecular target in colorectal cancer treatment was researched, we found that curcumin can decrease the level of P53 in tumor tissue, thereby promoting tumor cell necrosis, the study results laid a theoretical foundation for the use of curcumin in the treatment of colorectal cancer, and have important guiding meaning. Part I. Immunohistochemical study of colorectal tumor-associated proteinsObjective: To investigate the correlation of expression of CEA, P53, Ki-67, GST-Ï€and pathological characteristics in colorectal carcinoma. Methods: The expression of CEA, P53, Ki-67, GST-Ï€were detected by SP immunohistochemical staining in the tissues of 63 cases of colorectal carcinoma admitted from January 2004 to June 2007, and the clinical data and follow-up documents were analyzed retrospectively.Results: The positive rates of CEA, P53, Ki-67 and GST-Ï€expression in colorectal cancer were 95.2%, 55.6%, 52.4% and 82.5% respectively. P53 and Ki-67 expression were significantly correlated with the Dukes stages and lymph node metastasis. The positive rates of P53 and Ki-67 expression were significantly higher in Dukes C, D stages than those in Dukes A, B stages. The expression of P53 had a positive correlation with that of Ki-67. Also, the expression of GST-Ï€also had a positive correlation with that of P53. P53 and Ki-67 expression were significantly related to the prognosis. The positive rate of P53 and Ki-67 expression were notably higher in patients survived over or equal to 1 year, under to the survived less than 1 year in evidence.Conclusion:CEA, P53, Ki-67 and GST-Ï€were significantly correlated with the invasion, metastasis and prognosis of colorectal carcinoma. The examination of CEA, P53, Ki-67, GST-Ï€may be useful for the estimation of the cell biological action and play an important role in determining prognosis of colorectal carcinoma. Part II. Proteomics study of colorectal cancer metastasis-associated proteinsObjective: The sentinel lymph node (SLN) is the first lymph node to which metastatic cancer cells spread. Therefore, detection of the differentially expressed proteins between normal lymph nodes (NLNs) and SLN micrometastasis (SLNMM) is of great significance in understanding the molecular mechanism of early metastasis. The aim of this study is to investigate the early metastasis-associated proteins in SLNMMs of colorectal cancer (CRC) through comparative proteome.Methods: Hydrophobic protein samples were extracted from individual-matched NLNs and SLNMMs of CRC. Differentially expressed protein spots were detected with two-dimensional electrophoresis and image analysis, subsequently identified by MALDI-TOF-MS, and then followed by Western blotting confirmation.Results: Forty proteins were found to be differentially expressed between NLNs and SLNMMs. Four proteins including hnRNP A1, Ezrin, Tubulin beta-2C and Annexin A1 highly expressed in SLNMMs were all related to the cellular pathways of tumor cell migration. Further immunohistochemistry staining of these four proteins showed the clinicopathological characteristics of these proteins in lymph node metastasis of CRC.Conclusion:Our data indicate variations of hydrophobic protein expression between NLNs and SLNMMs in CRC and the increased expression of hnRNP A1, Ezrin, Tubulin beta-2C and Annexin A1 in SLNMMs suggests a significantly elevated incidence of early metastasis in CRC. Part III. Regulation of the expression of P53: the possible mechanism of Curcumin inhibiting the metastasis of colorectal cancerObjective: Treatment of advanced cancer is still difficult; radiotherapy, chemotherapy and some biological therapies are the major choices for those not suitable for surgical treatment. The present study aimed to examine the inhibitory mechanism of curcumin on cancer cells in a group of patients with colorectal cancer.Method: A total of 126 patients with colorectal cancer were recruited in this study. Sixty-three patients were received curcumin treatment during the period of waiting for surgery. Cancer specimens were collected at diagnostic biopsy and surgically removed tumor tissue. Body weight was recorded for each patient; serum tumor necrosis factor (TNF)-alpha, p53 and apoptotic cells in tumor tissue were examined.Results: The treatment with curcumin improved body weight loss, decreased serum TNF-alpha, increased apoptotic tumor cells, decreased p53 molecule expression in tumor tissue and modulated tumor cell apoptotic pathway.Conclusion: We conclude that treatment with curcumin improves the health condition of patients with colorectal cancer via decreasing the expression of p53 in tumor cells and subsequently speeds up tumor cell apoptosis.