| BackgroundProstate cancer is the most common form of male urinary system cancer, which mostly occurs in men over the age of 50. Prostate cancer is the most common male cancer in Western Europe and the United States, and its'incidence is at the second place in the malignant tumors in Western Europe. And it has become the mainly cause of death in male cancer patients. In recent years, the incidence of this disease is increasing due to the changes in people's diet as well as the lifestyle. Epidemiological researchers have found that the incidence of prostate cancer is affected by several environmental and genetic elements, such as: the increasing of androgen levels, obesity, increasing age, smoking, heavy drinking, and family history. However, the specific incidence of prostate cancer is still unclear, so there are extensive researches conducted by many experts and scholars on the cytology of prostate cancer.The prostate cancer has two states: the androgen-dependent and androgen-independent. Removing the hormone treatment can well control the growth of the androgen-dependent prostate cancer cell, and the transmitting of the androgen receptor signal will induce the death of the cancel cell. When the cancer cells change to hormone-dependent, the anti-androgen therapy will be in-effective and the disease worsen rapidly. In fact, when the diagnosis of the prostate cancer, over half of the patients have developed to local advanced or metastatic prostate cancer, which have lost the opportunity of radical surgery. And the only treatment is to use the comprehensive endocrine treatment, which is based on blocking the androgen. Most patients, who undergo the estrogen or castration surgery, will gradually transform into androgen-independent prostate cancer from androgen-dependent prostate cancer. And after the transformation, the prostate cancer cells'sensitivity to chemotherapy also decreased and the result of the treatment is often not well. Currently, chemotherapy is the main treatment to the hormone-independent prostate cancer, and usually the maximum tolerated dose will be chosen which is based on high-dose chemotherapy. The significant side effects limit its widespread use in the clinic. On the other side, low-doses of chemotherapy drugs, which are able to affect cell and protein expression of certain genes, increase the sensitivity of tumor cells to apoptosis, as well as avoid significant cytotoxicity, have broad application prospects. As a result, delaying the transformation of androgen-independent prostate cancer from the androgen-independent prostate cancer as well as exploring the treatment of the androgen-dependent prostate cancer treatment has become the focus of prostate cancer research subjects.In the process of exploring the root cause of the prostate cancer, people found that the expression of serum leptin levels increased gradually in most advanced prostate cancer patients. It is proved that leptin plays a crucial role in prostate cancer's occurrence and development. Some scholars use leptin to stimulation the androgen-independent prostate cancer PC-3 cells in vitro, and they found the over expression of the vascular endothelial growth factor (vascular endothelial growth factor, VEGF), transforming growth factor-β1 (transforming growth factor-β1, TGF-β1) and basic fibroblast growth factor (basic fibroblast growth factor, bFGF), as well as the increasing activity of the PC-3 prostate cancer cell migration. The result shows that leptin plays a certain role in promoting androgen-independent prostate cancer Cell proliferation as well as inducing cell migration.Anthracycline anticancer drug is a classic representative of adriamycin (ADM), which has a broad spectrum anti-tumor and effective. It adverse effect on the bone marrow suppression limits it widespread and long-term usage. So cancer drugs workers actively explores new anthracycline anticancer drugs with better efficacy but toxic side effects. THP pirarubicin, also known as topiramate stars (THP), is semi-synthetic anthracycline anti-tumor compounds. It is the substituted derivatives of ADM4-O-pyran-. Studies found that the chemotherapy drug doxorubicin toxicity at low-doses can increase the tumor necrosis factor-related apoptosis-inducing ligand (TNF-related apoptosis-inducing ligand, TRAIL) on steroid-dependent LNCaP prostate cancer cells induced apoptosis and its'mechanism related to the inhibition of c-FLIP.Tumor necrosis factor-related apoptosis inducing ligand (TRAIL) is a newly discovered new member of tumor necrosis factor family and it can induce apoptosis of most tumor cells but had no effect on most normal cells. The induction of apoptosis of tumor cells through its receptor-mediated. Currently, 5 receptors have been found: death receptors DR4 and DR5 (the existence of intracellular death domain)-induced apoptosis of tumor cells, soluble receptor (OPG) and DCR1 (no cell death within the structure Domain) and DCR2 (intracellular death domain is not complete), all of these 5 receptors won't transmit TRAIL death signal. TRAIL plays a key combination with the DR5 induced apoptosis at physiological conditions. Related research suggests that DR5-mediated signaling pathway play an important position in TRAIL-induced apoptosi.Purpose:This study was designed to study the expression of leptin in prostate cancer cells and the relevance on the inhibitory effect of the pirarubicin to human prostate cancer DU-145 cell line cycle. Low expression of leptin influences the therapeutic effect of pirarubicin on the prostate cancer. Finally, Provide new treatment strategy on prostate cancer to enhance the clinical efficacy, improve patient outcomes and prolong survival.Methods: 1. Using vitro cell culture. The experimental cells, hormone-dependent prostate cancer DU-145 line cells, were purchased from cell bank of Shanghai Institute.2. Subculture, logarithmic growth phase DU-145 cells were planted 96, leptin (100ng/ml) 24h after the randomized intervention, divided into negative control group, leptin intervention group and intervention group, adding different concentrations of leptin antagonists. Use MTT method to survey the cell activity in each group (OD) respectively and then calculate rate of cell growth inhibition.3. Take logarithmic growth phase DU-145 cells were added 24h after the intervention 100ng/ml leptin, randomized, divided into 6 groups, that is: control group, human recombinant leptin antagonist group, pirarubicin 0.5mg / L group, pirarubicin 1.0mg / L group, recombinant human leptin antagonist + pirarubicin 0.5mg / L group, recombinant human leptin antagonist + pirarubicin 1.0mg / L group . Use MTT method to survey the above 6 groups'vitro prostate cancer DU-145 cells in 24h, 48h of cell proliferation respectively.4. Use flow cytometry to detect the cell cycle inhibition of the above 6 groups'DU-145 prostate cancer cells in 24h, 48h.5. Adopt Western blotting method to detect the expression of DR5 of the above 6 groups'DU-145 prostate cancer cells respectively.6. Use SPSS13.0 software to conduct the statistical analysis on the results.Results:1. MTT method showed that: all groups'cell proliferation activity was significantly better than the control group under the intervention of the 100ng/ml leptin. In human leptin antagonist group 50ng/ml recombinant, the growth of DU-145 cells significantly inhibited and the cell growth inhibition rate was: 15.86%±0.82%. When continually increasing the dose, there was no clear effect on inhibiting the growth of DU-145cells. 2. MTT method showed that: (1) Only use pirarubicin group to intervene, the DU-145 cells were significantly inhibited. And with increasing doses, there was increasing rate of cell growth inhibition. In each group there was significant difference (P <0.05); (2) There were significant different (P <0.05) cell inhibition rate in 24h and 48h; (3) Compared with signal drug group, in combination therapy, the inhibition rate of cell growth increased gradually with the dose increasing and time increasing. There was significant difference (P <0.05).3. The results of the flow cytometry showed that:(1). There was significant difference (P <0.05) in signal leptin antagonist group, that is, compared with control group, there was higher rate of G1 phase cell and lower rate of G2 phase cell in DU-145 cells.(2). Compared with control group, there was significant difference (P <0.05) in signal pirarubicin group. That is, there was significant increase of S phrase cell in DU-145 cells.(3). Compared with control group and individual treatment group, there was significant difference (P <0.05) in combined treatment group. That is, there was increased rate of G1 and S phrase in DU-145 cells compared with pirarubicin group, and there was clearly increased rate in S phrase in DU-145 cells compared with leptin antagonist group.4. Western blotting results showed that: compared with single treatment group, there was increased DR5 expression with increasing doses of pirarubicin and time increasing in combined treatment group. And there was significant difference (P <0.05) among the groups.Conclusion:Pirarubicin combined with leptin inhibitors can inhibit the hormone leptin-independent DU-145 prostate cancer cell proliferation; increase the expression of the apoptosis-related protein. With the increasing in the concentration of pirarubicin, there was increasing trend either in the prostate cancer cell proliferation inhibition or the expression of the related protein. |
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