The Detection Of Circulating Bmi-1 MRNA In Colorectal Cancer And Its Significance

Backgroud and Purpose Colorectal cancer(CRC) is the most common malignancy in the digest system,but detection and treatment of this disease at an early stage and rationally judge therapeutic efficacy can dramatically improve survival.So,accurate diagnosis and prognostication for individual patients with CRC is essential for planning treatment strategies.Traditional clinical and histologic markers such as P53,CEA,et al, are commonly used today,but the sensitivity and accuracy of these parameters are still unsatisfactory.The Bmi-1 proto-oncogene is a transcriptional repressor which originally identified as a c-myc cooperating oncogene.Deregulation of Polycomb member Bmi-1 is involved in cell proliferation and human oncogenesis.Expression of Bmi-1 is found in several tumor tissues,including colorectal cancer gastric cancer,breast and so on;Now, experiments have indicated that Bmi-1 protein regulates the INK4a/ARF locus,which encodes the two tumor suppressors,p16^INK4a and p^19ARF which act in pRb and p53 cell cycle control pathways.Free plasma mRNA has been studied extensivly in patients with cancer in recent years which is thought to have correlations with early diagnosis and prognosis. Here we investigate the presence at diagnosis of detectable Bmi-1mRNA and the possible correlations between this event and a series of clinical pathological parameters of the tumors and hope to find a new method to diagnose colorectal cancerMaterials and Methods Between August 2008 and Octobor 2008,blood samples (10 mL) were taken from 44 patients with colorectal cancer by venipuncture before the day of surgery.Plasma was prepared by centrifugation of peripheral blood at 10 000 rpm for 15 minutes at 4℃temperature and diviede into aliqutors,which were snap-frozen at -80℃untill use.It is also to the 18 of controls and 15(the last hospital number is double) of after sugery at the third day.Bmi-1 mRNA expression levels were quantified by Fluorescence Quantitative PCR.Clinical and pathological data,including gender,ages, lymph node status,and p53 et al were all collected.Reuslts The cancer patiens with the presence of Bmi-1mRNA in plasma have higher levels than healty controls and decreased dramatically after tumor removal.The higher expression levels have no correlation with well-established markers of poor clinical outcome in colorectal cancer such as postive p53,lymph nodes metastasis,but we also observe that the trend of high expression of Bmi-1 mRNA correlate with the progress of Dukes classification,postive ofβ-catenin expression and large tumors which diametres exceed 5 cm.Conclusion 1.Bmi-1 mRNA is detectable in all samples.2.Our results suggest that levels of Bmi-1 expression are higher than control group and decrease after surgery.It may be a surrogate of curative effect and noninvasive diagnostic markers and become clinically useful.