RESUMO
Emerging evidence supports that prostate cancer originates from a rare subpopulation of cells, namely prostate cancer stem cells (CSCs). Conventional therapies for prostate cancer are believed to mainly target the majority of differentiated tumor cells but spare CSCs, which may account for the subsequent disease relapse after treatment. Therefore, successful elimination of CSCs may be an effective strategy to achieve complete remission from this disease. Gamma-tocotrienols (γ-T3) is one of the vitamin-E constituents, which have been shown to have anticancer effects against a wide range of human cancers. Recently, we have reported that γ-T3 treatment not only inhibits prostate cancer cell invasion but also sensitizes the cells to docetaxel-induced apoptosis, suggesting that γ-T3 may be an effective therapeutic agent against advanced stage prostate cancer. Here, we demonstrate for the first time that γ-T3 can downregulate the expression of prostate CSC markers (CD133/CD44) in androgen-independent prostate cancer cell lines (PC-3 and DU145), as evident from Western blotting analysis. Meanwhile, the spheroid formation ability of the prostate cancer cells was significantly hampered by γ-T3 treatment. In addition, pretreatment of PC-3 cells with γ-T3 was found to suppress tumor initiation ability of the cells. More importantly, although CD133-enriched PC-3 cells were highly resistant to docetaxel treatment, these cells were as sensitive to γ-T3 treatment as the CD133-depleted population. Our data suggest that γ-T3 may be an effective agent in targeting prostate CSCs, which may account for its anticancer and chemosensitizing effects reported in previous studies.
Assuntos
Antineoplásicos/farmacologia , Cromanos/farmacologia , Células-Tronco Neoplásicas/efeitos dos fármacos , Neoplasias da Próstata/patologia , Vitamina E/análogos & derivados , Animais , Western Blotting , Linhagem Celular Tumoral , Humanos , Masculino , Camundongos , Camundongos Nus , Células-Tronco Neoplásicas/patologia , Vitamina E/farmacologia , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
The recent introduction of docetaxel in the treatment of hormone refractory prostate cancer (HRPC) has made a small but significant impact on patient survival. However, its effect is limited by intolerance and resistance. The aim of our study was to investigate if the garlic-derived compound, S-allylmercaptocysteine (SAMC), was able to act as a docetaxel sensitizing agent. First, the effect of SAMC on docetaxel sensitivity was examined on 3 HRPC cell lines by colony forming assay. We found that SAMC increased the efficacy of docetaxel on colony forming inhibition by 9-50% compared to single agent treatment. Second, using the HRPC CWR22R nude mice model, we found that the combination of SAMC and docetaxel was 53% more potent than docetaxel alone (p = 0.037). In addition, there was no additive toxicity in the mice treated with the combination therapy evidenced by histological and functional analysis of liver, kidney and bone marrow. These results suggest that SAMC is able to increase the anticancer effect of docetaxel without causing additional toxic effect in vivo. Third, flow cytometry and Western blotting analysis on HRPC cell lines demonstrated that SAMC promoted docetaxel-induced G2/M phase cell cycle arrest and apoptotic induction. In addition, immunohistochemistry on CWR22R xenograft revealed a suppression of Bcl-2 expression and upregulation of E-cadherin in the SAMC and docetaxel treated animals. These results suggest that SAMC may promote docetaxel-induced cell death through promoting G2/M cell cycle arrest and apoptosis. Our study implies a potential role for SAMC in improving docetaxel based chemotherapy for the treatment of HRPC.
Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/farmacologia , Apoptose/efeitos dos fármacos , Cisteína/análogos & derivados , Alho , Neoplasias da Próstata/tratamento farmacológico , Neoplasias da Próstata/metabolismo , Taxoides/farmacologia , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Western Blotting , Caderinas/metabolismo , Divisão Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Cisteína/efeitos adversos , Cisteína/farmacologia , Docetaxel , Regulação para Baixo/efeitos dos fármacos , Sinergismo Farmacológico , Citometria de Fluxo , Fase G2/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Humanos , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Nus , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Taxoides/efeitos adversos , Transplante Heterólogo , Ensaio Tumoral de Célula-Tronco , Regulação para Cima/efeitos dos fármacosRESUMO
The presence of circulating tumor cells (CTC) is common in prostate cancer patients, however until recently their clinical significance was unknown. The CTC stage is essential for the formation of distant metastases, and their continuing presence after radical prostatectomy has been shown to predict recurrent or latent disease. Despite their mechanistic and prognostic importance, due both to their scarcity and difficulties in their isolation, little is known about the characteristics that enable their production and survival. The aim of this study was to investigate the molecular mechanisms underlying the survival of CTC cells. A novel CTC cell line from the bloodstream of an orthotopic mouse model of castration-resistant prostate cancer was established and compared with the primary tumor using attachment assays, detachment culture, Western blot, flow cytometry and 2D gel electrophoresis. Decreased adhesiveness and expression of adhesion molecules E-cadherin, beta4-integrin and gamma-catenin, together with resistance to detachment and drug-induced apoptosis and upregulation of Bcl-2 were integral to the development of CTC and their survival. Using proteomic studies, we observed that the GRP94 glycoprotein was suppressed in CTC. GRP94 was also shown to be suppressed in a tissue microarray study of 79 prostate cancer patients, indicating its possible role in prostate cancer progression. Overall, this study suggests molecular alterations accounting for the release and survival of CTC, which may be used as drug targets for either anti-metastatic therapy or the suppression of latent disease. We also indicate the novel involvement of GRP94 suppression in prostate cancer metastasis.
Assuntos
Anoikis/fisiologia , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Membrana/metabolismo , Células Neoplásicas Circulantes/metabolismo , Neoplasias da Próstata/sangue , Neoplasias da Próstata/patologia , Animais , Western Blotting , Adesão Celular/fisiologia , Linhagem Celular Tumoral , Sobrevivência Celular/fisiologia , Citometria de Fluxo , Humanos , Imuno-Histoquímica , Masculino , Camundongos , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise Serial de TecidosRESUMO
OBJECTIVE: To evaluate the effect of S-allylcysteine (SAC) on CWR22R, a human androgen-independent (AI) prostate cancer xenograft, in nude mice. Despite extensive research worldwide there is no effective way to control the growth of prostate cancer, and we previously reported that SAC and S-allylmercaptocysteine (SAMC), two water-soluble derivatives of garlic, inhibit cancer cell invasion through restoration of E-cadherin expression in vitro. MATERIALS AND METHODS: The effects of SAC on tumour cell proliferation markers such as Ki-67 and proliferating cell nuclear antigen, and apoptotic regulators including Bcl-2 and cleaved caspase-3, were assessed by immunohistochemical staining. The inhibitory effects of SAC on prostate cancer invasion was examined by immunoreactivity of E-cadherin and its binding proteins alpha, beta and gamma-catenins. The serum prostate-specific antigen (PSA) level at three different times (initiation, middle and end of treatment) and toxicity of SAC on several organs after treatment were assessed. RESULTS: Treatment with SAC resulted in inhibition of the growth of CWR22R, with no detectable toxic effect on nude mice. The SAC-induced growth reduction was correlated with a concurrent reduction in serum PSA level and proliferation rate of xenografts, together with an inhibition of invasion through the restoration of E-cadherin and gamma-catenin expression. Furthermore, the apoptotic rate of SAC-treated tumours increased together with a decrease in Bcl-2 and increase in cleaved caspase-3. CONCLUSION: These results suggest that this garlic-derived compound might be a potential therapeutic agent for suppressing AI prostate cancer.
Assuntos
Antineoplásicos/farmacologia , Cisteína/análogos & derivados , Neoplasias Hormônio-Dependentes/tratamento farmacológico , Neoplasias da Próstata/tratamento farmacológico , Androgênios/metabolismo , Animais , Cisteína/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Masculino , Camundongos , Camundongos Nus , Neoplasias Hormônio-Dependentes/patologia , Antígeno Prostático Específico/sangue , Neoplasias da Próstata/patologia , Transplante Heterólogo , Resultado do TratamentoRESUMO
The failure of prostate cancer treatment is largely due to the development of androgen independence, since the androgen depletion therapy remains the front-line option for this cancer. Previously, we reported that over-expression of the helix-loop-helix protein Id-1 was associated with progression of prostate cancer and ectopic expression of Id-1 induced serum-independent proliferation in prostate cancer cells. In the present study, we investigated if exogenous Id-1 expression in the androgen sensitive LNCaP cells had any effect on androgen-dependent cell growth and studied the molecular mechanisms involved. Using stable Id-1 transfectants, we found that expression of Id-1 was able to reduce androgen-stimulated growth and S phase fraction of the cell cycle in LNCaP cells, indicating that Id-1 may be involved in the development of androgen independence in these cells. The Id-1-induced androgen-independent prostate cancer cell growth was correlated with up-regulation of EGF-R (epidermal growth factor-receptor) and PSA (prostate specific antigen) expression, as confirmed by western blotting analysis and luciferase assays. In contrast, down-regulation of Id-1 in androgen-independent DU145 cells by its antisense oligonucleotides resulted in suppression of EGF-R expression at both transcriptional and protein levels. In addition, the results from immunohistochemistry study showed that Id-1 expression was significantly elevated in hormone refractory prostate cancer tissues when compared with the hormone-dependent tumours. Our results suggest that up-regulation of Id-1 in prostate cancer cells may be one of the mechanisms responsible for developing androgen independence and this process may be regulated through induction of EGF-R expression. Inactivation of Id-1 may provide a potential therapeutic strategy leading to inhibition of androgen-independent prostate cancer cell growth.
Assuntos
Androgênios/farmacologia , Receptores ErbB/fisiologia , Neoplasias da Próstata/patologia , Proteínas Repressoras , Fatores de Transcrição/genética , Adenocarcinoma/patologia , Animais , Divisão Celular/efeitos dos fármacos , Divisão Celular/genética , Linhagem Celular Tumoral , Núcleo Celular/fisiologia , Receptores ErbB/genética , Humanos , Imuno-Histoquímica , Proteína 1 Inibidora de Diferenciação , Masculino , Camundongos , Camundongos Nus , NF-kappa B/antagonistas & inibidores , Nitrilas/farmacologia , Regiões Promotoras Genéticas , Sulfonas/farmacologia , Transfecção , Transplante HeterólogoRESUMO
Using two-dimensional gel electrophoresis, we investigated the profile of prostatic secretory proteins in human expressed prostatic secretion (EPS) from benign prostate hyperplasia (BPH) patients and compared the patterns with normal controls. We identified three specifically expressed proteins, including prostate secretory protein 61 (PSP61), in EPS from benign BPH patients but absent in normal controls. In addition, we found that PSP61 was a modified isoform of the well-documented PSP-94, which had a perfect matching (100% homology) to the first 61 amino acids of the PSP-94 protein but with a deleted C-terminus. This shortened PSP61 was not due to alternative splicing of the PSP-94 gene at transcription level. Our results provide first evidence on the possibility of using PSP61 as a specific biological marker for diagnosis of BPH.