Effects Of Andrographolide On Proliferation, Invasion And Expression Of Interleukin-6of Prostate Cancer DU145Cells

Objective: Today, prostate cancer has become a major health problem,being the most frequently diagnosed noncutaneous cancer and thesecond-leading cause of cancer-related deaths in men worldwide.Androgen-deprivation therapy is the major treatment in recurrent andmetastatic prostate cancer. However, in most cases, prostate cancer progressesto an apoptosis resistant androgen-independent stage for which there is noavailable therapy. It is therefore important to understand the molecularmechanisms underlying prostate cancer progression, and how prostate cancercells evade apoptotic mechanisms that give rise to their uncontrolled growthbehaviour. However, while we await more conclusive evidences of good drugtargets in prostate cancer, there is a need to discover new agents that have thepotential to induce growth arrest and apoptosis in metastatic prostate cancercells.Interleukin-6(IL-6), a major mediator of the inflammatory response, hasbeen implicated in androgen receptor (AR) activation, cellular growth anddifferentiation, plays important roles in the development and progression ofprostate cancer, and is a potential target in cancer therapy. Andrographolide(AGP) is a natural compound isolated from Andrographis paniculata, whichexhibits a wide spectrum of biological activities of therapeutic importanceincluding antibacterial, anti-inflammatory, antimalarial, and anticancerproperties and used extensively in the traditional medicine of India and China.Currently, andrographolide effects on prostate cancer cells and its mechanismis rarely reported at home and abroad. This topic intends to study the effect ofandrographolide on DU145prostate cancer cell proliferation, cell invasion andand its effect on the expression of IL-6, STAT3phosphorylation, and exploreits possible mechanism of action, in order to seek new effective drugs for the treatment of hormone-dependent prostate cancer and provide basicinformation for the IL-6/STAT3signaling pathway of targeted cancer therapy.Method: Human prostate cancer DU145cells were cultivated in vitroand then treated with various concentrations of Andrographolide. MTT assaysand cell counting were performed to investigate the effects of AGP onproliferation in DU145cells. Using microscope observed the change ofmorphologic of DU145cells.Effect of andrographolide on IL-6proteinexpression was measured by enzyme-linked immunosorbent assay(ELISA).Expression of Stat3in DU145cells was detected by Western blot assay. Theresults were analyzed by SPSS13.0, and we established the standard ofstatistic significance as p<0.05.Results:1Andrographolide inhibits cell viability and cell invasion：To determinewhether andrographolide affects prostate cancer cell growth, human prostatecancer cell lines DU145were treated with increasing doses of andrographolide.MTT assays and cell counting were performed to investigate the effects ofAGP on proliferation in DU145cells. Results suggested that AGP inhibitsDU145proliferation (P<0.05). Observed using a microscope found that theDU145cells exposed to AGP became round, small, cell shrinkage, membraneblebbing and so on. To determine the effects of andrographolide on cellinvasion, DU145cells were treated with different doses of andrographolide,and invasion was determined as the ability of cells to penetrate throughMatrigel in invasion assay as described. The data of Transwell invasion assaysuggest that andrographolide inhibits prostate cancer cell invasion（P <0.05).2Andrographolide inhibits IL-6expression：In an attempt to identifypotential inhibitors of IL-6, DU145human prostate cancer cells that expressIL-6autocrine loop were treated with andrographolide for24hours. Themedia were collected and used for measurement of IL-6protein by ELISA.The data showed that andrographolide inhibits IL-6expression at protein levelin dose-effect manner (P<0.05). 3Andrographolide antagonizes IL-6–induced signaling：Human prostatecancer cell lines(DU145cells)that express constitutive IL-6autocrine loopwere treated with increasing doses of andrographolide, and cell lysates werecollected and analyzed for protein expression. The results of Western botindicate that andrographolide was able to block IL-6–stimulated STAT3phosphorylation.Conclusions: Andrographolide could inhibits cell viability and cellinvasion in hormone-refractory prostate cancer DU145cells possibly bysuppresses both IL-6expression and IL-6–induced signaling including STAT3phosphorylation.