Inhibition of telomerase with human telomerase reverse transcriptase antisense increases the sensitivity of tumor necrosis factor-α-induced apoptosis in prostate cancer cells

Aim： To investigate the effect of inhibition of telomerase with human telomerase reverse transcriptase （hTERT） antisense on tumor necrosis factor-α （TNF-α-induced apoptosis in prostate cancer cells （PC3）. Methods： Antisense phosphorothioate oligodeoxynucleotide （AS PS-ODN） was synthesized and purified. Telomerase activity was measured using the telomeric repeat amplification protocol （TRAP） and polymerase chain reaction enzyme-linked immunoassay （PCR-ELISA）. hTERT mRNA was measured by reverse transcription PCR （RT-PCR） assay and gel-image system, hTERT protein was detected by immunochemistry and flow cytometry. Cell viability was detected by 3-（4, 5-dimethylthiazol-2-yl）-2,5-Diphenyltetrazolium （MTT） assay. Cell apoptosis was observed by morphological method and determined by flow cytometry. Results： The telomerase activity decreased with time after hTERT AS PS-ODN treatment. The levels of hTERT mRNA decreased with time after hTERT AS PS-ODN treatment, which appeared before the decline of the telomerase activity. The percentage of positive cells of hTERT protein declined with time after hTERT AS PS-ODN treatment, which appeared after the decline of hTERT mRNA. There was no difference in telomerase activity, hTERT mRNA and protein levels between hTERT sense phosphorothioate oligodeoxynucleotide （S PS-ODN） and the control group. The cell viability decreased with time after hTERT AS PS-ODN combined with TNF-α treatment. The percentage of apoptosis increased with time after hTERT AS PS-ODN combined with TNF-α treatment. There was no difference in cell viability and the percentage of apoptosis between hTERT S PS-ODN and the control group. Conclusion： hTERT AS PS-ODN can significantly inhibit telomerase activity by downregulating the hTERT mRNA and protein expression, and inhibition of telomerase with hTERT antisense can enhance TNF-α- induced apoptosis of PC3 cells.

Expression of Nkx3.1 enhances 17β-estradiol anti-tumor action in PC3 human prostate cancer cells

Aim： To explore whether the anti-tumor action of 17β-estradiol is enhanced by re-expression of the homeodomain transcription factor Nkx3.1 in PC3 human prostate cancer cells. Methods： PC3 cells were stably transfected with pcDNA3.1-Nkx3.1-His vector, which carries a full-length cDNA of human Nkx3.1. The PC3 cells stably transfected with vector pcDNA3.1 were set as a control. The expression of Nkx3.1 protein in the cells was confirmed by Western blot analysis. The effect of Nkx3.1 on cell proliferation of PC3 cells was examined with MTT assay. The antiproliferative and apoptotic effects of 17β-estradiol alone or in combination with Nkx3.1 were estimated on PC3 cells by using MTT growth tests and flow cytometric analyses. The expression of apoptosis-related proteins was analyzed using Western blotting. Results： The plasmid carrying Nkx3.1 gene induced high expression of Nkx3.1 protein in PC3 cells. The re-expression of exogenous Nkx3.1 did not cause a significant reduction in cellular proliferation, whereas the expression of Nkx3.1 enhanced the 17β-estradiol anti-proliferative effect in PC3 cells. Nkx3.1 expres- sion promoted 17β-estradiol-induced apoptosis of PC3 cells, as shown by analysis of Bcl-2, Bax, Caspase-3 and poly （ADP-ribose） polymerase expression. Conclusion： The present study demonstrates that re-expression of Nkx3.1 enhances 17β-estradiol anti-tumor action in PC3 human prostate cancer cells. The in vitro study suggests that re- expression of Nkx3.1 is worthy of further consideration as an adjuvant treatment of androgen independent prostate cancer with estrogen anti-tumor therapies.

The multikinase inhibitor sorafenib induces caspase-dependent apoptosis in PC-3 prostate cancer cells

The present study investigated the effects of the multikinase inhibitor sorafenib on androgen-independent can- cer cells viability and intracellular signaling. Human androgen-independent PC-3 prostate cancer cells were treated with sorafenib. At concentration that suppresses extracellular signal-regulated kinase phosphorylation, sorafenib treatment reduced the mitochondrial transmembrane potential. Sorafenib also down-modulated the levels of mye- loid cell leukemia 1, survivin and cellular inhibitor of apoptosis protein 2. Sorafenib induced caspase-3 cleavage and the mitochondrial release of cytochrome c. However, no nuclear translocation of apoptosis inducing factor was detected after treatment and the pan-caspase inhibitor Z-VAD-FMK had an obvious protective effect against the drug. In conclusion, sorafenib induces apoptosis through a caspase-dependent mechanism with down-regulated antiapoptotic proteins in androgen-independent prostate cancer cells in vitro.

Effects of 9-cis retinoic acid on human homeobox gene NKX3.1 expression in prostate cancer cell line LNCaP

Aim:To study the regulatory effects of 9-cis retinoic acid(RA)on the expression of human homeobox gene NKX3.1 in prostate cancer cell line LNCaP.Methods:Flow cytometry,reverse transcriptase polymerase chain reaction and Western blotting were performed to evaluate the effects of 9-cis RA on NKX3.1 expression and cell cycle of LNCaP cells.To identify a regulatory region within the NKX3.1 promoter contributing to the regulation induced by 9-cis RA, we have constructed an NKX3.1 promoter-reporter plasmid,pGL_3-1040bp,and its 5′-deletion mutants,which were transfected into LNCaP cells with treatment of 9-cis RA in indicated concentrations.Results:With the treatment of 9-cis RA,the NKX3.1 promoter activity was increased in reporter gene assay and NKX3.1 expression was enhanced at both mRNA and protein levels in LNCaP cells.We found that the region between -936 and -921 in the upstream of NKX3.1 gene involved the inducible regulation by 9-cis RA treatment.In flow cytometry,9-cis RA treatment caused accumulation of cells in the G_1 phase of the cell cycle and a fewer cells pass through to G_2/M.Conclusion:Our results demonstrated that 9-cis RA as a differentiating agent can arrest prostate cancer cells in G_1 phase and reduce cell mitosis,and upregulate the expression of human homeobox gene NKX3.1,which is thought to play an important role in prostate differentiation and to act as a tumor suppressor gene in the prostate.(Asian J Androl 2006 Jul;8:435-441)

Effect of miR-296 on the Apoptosis of Androgen-independent Prostate Cancer Cells

Objective To investigate the miR-296＇s function in prostate carcinoma（PCa） cells. Methods In order to profile the miRNA expression in LNCaP cells, the cultured cells were stimulated with androgen after 48-h starvation, miRNA microarray analysis and Q-RT-PCR assay were performed. To characterize the effects of miR296 on PCa cells, CL-1 and PC-3 cells were transfected with miR-296 and antisense-miR-296, cell growth and apoptosis were then analyzed. Results The miR-296-5p expression was up-regulated by 2.22 folds in the CL-1 cells, which do not express significantly androgen receptor, than in LNCaP cells. Knockdown of miR-296-5p induced apoptosis of CL-1 cells, but not LNCaP cells. However, knockdown of miR-296-5p inhibited the growth rate of LNCaP cells cultured in absence of androgen. Conclusion MiR-296-5p could be important for development of prostate cancer from androgen dependence to androgen independence.

Loss of the vitamin D receptor in human breast and prostate cancers strongly induces cell apoptosis through downregulation of Wnt/β-catenin signaling

Vitamin D co-regulates cell proliferation, differentiation and apoptosis in numerous tissues, including cancers. The known anti-proliferative and pro-apoptotic actions of the active metabolite of vitamin D, 1,25-dihydroxy-vitamin D [1,25（OH）2D] are mediated through binding to the vitamin D receptor （VDR）. Here, we report on the unexpected finding that stable knockdown of VDR expression in the human breast and prostate cancer cell lines, MDA-MB-231 and PC3, strongly induces cell apoptosis and inhibits cell proliferation in vitro. Implantation of these VDR knockdown cells into the mammary fat pad （MDA-MB-231）, subcutaneously （PC3） or intra-tibially （both cell lines） in immune-incompetent nude mice resulted in reduced tumor growth associated with increased apoptosis and reduced cell proliferation compared with controls. These growth-retarding effects of VDR knockdown occur in the presence and absence of vitamin D and are independent of whether cells were grown in bone or soft tissues. Transcriptome analysis of VDR knockdown and non-target control cell lines demonstrated that loss of the VDR was associated with significant attenuation in the Wnt/0-catenin signaling pathway. In particular, cytoplasmic and nuclear β-catenin protein levels were reduced with a corresponding downregulation of downstream genes such as Axin2, Cyclin D1, interleukin-6 （IL-6）, and IL-8. Stabilization of 0-catenin using the GSK-3β inhibitor BIO partly reversed the growth-retarding effects of VDR knockdown. Our results indicate that the unliganded VDR possesses hitherto unknown functions to promote breast and prostate cancer growth, which appear to be operational not only within but also outside the bone environment. These novel functions contrast with the known anti-proliferative nuclear actions of the liganded VDR and may represent targets for new diagnostic and therapeutic approaches in breast and prostate cancer.

Effect of hypoxia-inducible factor-1α on proliferation and invasion of prostate cancer PC-3 cell in hypoxic situation

Objective We transfected recombinant expression plasmid of pcDNA3. 1-HIF-1α into prostate cancer cells, to research effect of HIF-1α on proliferation of prostate cancer cell PC-3. Methods We selected a stable expression cell line with G418 we selected by transfection

Fu-Zheng-Yi-Liu Formula inhibits the stem cells and metastasis of prostate cancer via tumor-associated macrophages/C-C motif chemokine ligand 5 pathway in tumor microenvironment

Prostate cancer(PCa)is the second most common malignancy among men globally.The Fu-Zheng-Yi-Liu(FZYL)Formula has been widely utilized in the treatment of PCa.This study investigates whether the FZYL Formula can inhibit PCa by tar-geting the TAMs/CCL5 pathway.We conducted in vitro co-cultures and in vivo co-injections of PCa cells and TAMs to mimic their in-teraction.Results showed that the FZYL Formula significantly reduced the proliferation,colony formation,subpopulations of PCSCs,and sphere-formation efficacy of PCa cells,even in the presence of TAM co-culture.Additionally,the Formula markedly decreased the migration,invasion,and epithelial-mesenchymal transition(EMT)of PCa cells induced by TAMs.The FZYL Formula also reversed M2 phenotype polarization in TAMs and dose-dependently reduced their CCL5 expression and secretion,with minimal cytotoxicity observed.Mechanistic studies confirmed that the TAMs/CCL5 axis is a critical target of the FZYL Formula,as the addition of exogen-ous CCL5 partially reversed the formula’s inhibitory effects on PCSCs self-renewal in the co-culture system.Importantly,the Formula also significantly inhibited the growth of PCa xenografts,bone metastasis,and PCSCs activity in vivo by targeting the TAMs/CCL5 pathway.Overall,this study not only elucidates the immunomodulatory mechanism of the FZYL Formula in PCa therapy but also highlights the TAMs/CCL5 axis as a promising therapeutic target.

Exogenous p27KIP1 expression induces anti-tumour effects and inhibits the EGFR/PI3K/Akt signalling pathway in PC3 cells

p27 is a cyclin-dependent kinase inhibitor that regulates the progression of cells from G1 to S phase of the cell cycle. Loss of p27 has been associated with disease progression and with an unfavourable outcome in prostate cancer. In this study, we investigated whether exogenous p27 expression in the human androgen-independent prostate cancer PC3 cell line had any effect on cell growth, and we studied the molecular mechanisms involved. p27 expression was restored in PC3 cells by plasmid delivery. Cell proliferation and apoptosis were assessed in PC3 cells transfected with p27. We also investigated the effects of p27 on the epidermal growth factor receptor （EGFR）/ phosphatidylinositol 3-kinase （PI3K）/Akt signalling pathway in PC3 cells. By restoring p27 expression in PC3 cells, we observed that p27 reduced proliferation and induced arrest in G0/G1 phase. Moreover, p27-transfected PC3 cells underwent apoptosis, as shown by flow cytometric analysis and western blotting analysis of Bcl-2, Bax, Bad, caspase-3 and poly（ADP-ribose）polymerase expression. Furthermore, the p27-induced anti-tumour action corre- lated with inhibition of the EGFR/PI3K/Akt signalling pathway, as confirmed by western blotting analysis and densitometry of EGFR, PI3K （p85）, Akt and p-Akts473 expression. Our results suggest that exogenous expression of p27 inhibits the proliferation of PC3 cells through induction of G1 arrest and apoptosis, and this process correlates with inhibition of the EGFR/PI3K/Akt signalling pathway.

RNA INTERFERENCE OF ANNEXIN II GENE IN PC3 CELLS BY USING SMALL INTERFERENCE RNA SYNTHESIZED WITH IN VITRO TRANSCRIPTION

Objective To silence annexin Ⅱ gene expression by using small interference RNA （siRNA） in prostate cancer cell line PC3. Methods For in vitro transcription, four sequences of 29-nucleotide DNA template oligonucleotides were designed, and one pair of the sequences were complementary to annexin Ⅱ gene. The other pair was negative control. The 8 nucleotides at the 3＇ end of each oligonucleotide were complementary to the T7 Promoter Primer. The sense and anti-sense siRNA templates were transcribed by T7 RNA polymerase and the resulting RNA transcripts were hybridized to create dsRNA. The siRNA was transfected into prostate cancer cell PC3. For assaying the efficiency of siRNA, confocal microscopy, Northern blotting, and Western blotting were employed to examine the expression of annexin Ⅱ protein and its mRNA. ^3H thymidine was used to measure DNA synthesis. Results The siRNA sequence specific to annexin Ⅱ gene was capable of inhibiting the expression of annexin Ⅱ protein and its mRNA. And cellular DNA synthesis was significantly reduced in siRNA transfected cells.Conclusions The protocol for the synthesis of siRNA by T7 RNA polymerase is feasible. Annexin Ⅱ might be involved in DNA synthesis.