The Expression Of Notch1 In Prostate Cancer And Its Effects On The Biological Behavior Of The Prostate Cancer

Prostate cancer is a common lethal malignancy among men in the west. The incidence and morality rates of prostate cancer have increased year by year. Although its morality rate is lower than that of lung cancer, its incidence rate is higher than that of lung cancer and become the highest incidence rate of cancer. In our country, prostate carcinoma is the third leading cause of cancer hi male genitourinary tumor. With the aging of population, prostate cancer is one of the common life threading diseases and it is important to study its affected factors. At present, the research of prostate cancer is the most popular topic.The Notch gene got its name from a strain of Drosophila with notched wing blades in 1916. The gene was cloned by Artavanis Tsakonas in 1980's. Notch genes encode 300 kDa single pass transmembrane receptors, compose of 2753 amino acid residues. Notch genes have been foundgenetically conserved in many species including humans. In vertebrates, four Notch genes have been described: Notchl, -2, -3, and -4. Notch signaling is involved in cell specification, proliferation, and apoptosis that affect the development and function of many organs. Pathophysiologic alterations in Notch signaling have been associated with tumorigenesis. Overexpression of active Notchl inhibited the proliferation of various prostate cancer cells, suggesting that Notch activation can also induce growth arrest and apparently reduce the neoplastic potential of tumors.In present study, our research is aimed to observe the expression of Notchl in prostate cancer and explore its preliminary function. The major findings of the present work are as follows:1. The expression of Notchl mRNA was analyzed by means of Semiquantitative RT-PCR in 38 samples with prostate cancer (Pea), 32 samples with benign prostatic hyperplasia (BPH) and 12 samples with normal prostate (NP). The results showed that Notchl mRNA was differentially expressed in three tissues. And significantly more BPH and NP than Pca expressed Notchl (P<0.05).2. To study the expression and significance of Notchl in 48 samples with prostate cancer (Pca), 66 samples with benign prostatic hyperplasia (BPH) and 18 samples with normal prostate (NP). We employed inimunohistochemical methods with monoclonal antibody against Notchl protein on archival prostate cancer materials. The results showed that Notchl protein was detected in 23 out of 48 cases of Pca, 48 out of 66 of BPH, 14 out of 18 of NP. The immunohistochemical results suggested thatexpression of Notchl in Pea was significantly lower than that in NP and BPH (P<0.01). Moreover, the positive rate of Notchl expression in cases of well and moderately differentiated prostate cancer was higher than that in poorly differentiated prostate cancer (P<0.05). And clinical Tl and T2 stages prostate cancer showed stronger Notchl expression than T3 and T4 stages cancer (P<0.05). However, the expression intensity of Notchl was not related with volume of prostate and level of serumal PSA (P>0.050).3. With Lipofectamine^TM2000, we transfected flourescence plasmid pRAMIC-IRESI-EGFP-Notchl and control plasmid into PC-3 cell line. The results showed that untransfection group could not produce green fluorescence; however, transfection group (including pRAMIC-IRES2-EGFP and control plasmid pIRES2-EGFP) could produce green fluorescence. And the transfection cells did not changed in the size and shape. Moreover, we compared the expression quantity of Notchl in the PC-3 cell line after transfection. It had been verified that the mRNA and protein expression of Notchl were steady in human PC-3 cell. The transfection rate were 57.74% in control plasmid pIRES2-EGFP and 55.52% in pRAMIC-IRESI-EGFP group.4. We also investigated that the growth, adhesion, ultramicrostrucrure, cell cycle, invasiveness and tumorigenesis ability in vitro of PC-3 after transfection. The results showed that the growth of PC-3 cell were inhibited, homogeneity adhesion rate decreased, malignant phenotype characteristic lost, cell cycle inhibition from G₁→S₀ and showed up a small apoptosis peak. Moreover, invasiveness cell count and tumorigenesis ability in vitro...