OBJECTIVE To evaluate if RNA helicase DDX20,highly expressed in triple negative breast cancer(TNBC)cells,could serve as a surrogate marker for simvastatin treatment response.METHODS We first assessed correlation betwe...OBJECTIVE To evaluate if RNA helicase DDX20,highly expressed in triple negative breast cancer(TNBC)cells,could serve as a surrogate marker for simvastatin treatment response.METHODS We first assessed correlation between 17 mevalonate pathway-related genes and expression of DDX20 in a cohort of 1325 breast cancer tumors.TNBC cells,MDA-MB-231,were then treated with simvastatin and mevalonate pathway intermediates to assess the alteration in DDX20 expression.In the mouse model,MDA-MB-231 cells were injected to tail veins of mice,groups of 8mice each were injected intraperioneally with vehicle or simvastatin 25mg·kg-1 3times a week for 6weeks.The number of metastatic colonies formed was quantified and immunohistochemical(IHC)staining of DDX20 was carried out in the lung tissues.RESULTS Among the 17 genes evaluated,positive correlation with DDX20 expression was observed in eight of them,with HMGCR having the highest correlation.Our in vitro experiments show exposure of breast cancer cells to simvastatin lead to a Rho-dependent decrease in gene expression of DDX20,leading to decreased tumor proliferation in a mevalonate pathway-dependent manner.Conversely,ectopic overexpression of DDX20 significantly abrogated the anti-metastatic activity of simvastatin.A similar observation is seen in the mouse model,where simvastatin-injected mice show significantly fewer visible lung metastases compared to placebo-fed mice.IHC staining on these lung tissues showed decreased DDX20 expression in simvastatin-injected group,corroborating our observations in vitro.CONCLUSION DDX20 is a potential surrogate marker for simvastatin treatment response in breast cancer and a long term implication of our findings is the possibility of an effective combinatorial therapeutic intervention using statins(to suppress DDX20 gene expression)and a suitable firstline agent″for the kill″of invasive breast cancer.展开更多
OBJECTIVE Doxorubicin-based therapy has been found to be not significantly effective for the treatment of advanced stage hepatocellular carcinomas(HCCs),which often undergo epithelial-mesenchymal transition(EMT)during...OBJECTIVE Doxorubicin-based therapy has been found to be not significantly effective for the treatment of advanced stage hepatocellular carcinomas(HCCs),which often undergo epithelial-mesenchymal transition(EMT)during tumor progression.Increasing evidence suggest(s)that epithelial cell transformation to mesenchymal state canenhance the ability to self-renew and confer greater resistance to the conventional chemotherapeutic drugs.The aim of this study was to examine the potential efficacyof ascochlorin,an isoprenoid antibiotic to overcome drug resistance induced by doxorubicin in HCC cell lines and to elucidate its underlying mechanism(s)of action.METHODS The effect of doxorubicin and ascochlorin on HCC cell lines was determined by MTT,Western blotting,immunofluorescence and NF-кB DNA binding assays.RESULTS Our results indicate that HCC cells that show a mesenchymal-like phenotype,are resistance to the doxorubicin therapy which directly correlated with an increased slug expression.We also observed that activation of NF-кB pathway plays an essential role in doxorubicin induced-chemoresistance and pharmacological inhibition of this pathway with ascochlorin can significantly reverse drug-induced invasion/migration and resistance in HCC cells.CONCLUSION Our results indicate that combination treatment of doxorubicin with ascochlorin has the potential to inhibit HCC growth and metastasis.展开更多
OBJECTIVE In prostate cancer(PCa),signal transducer and activator of transcription factor3(STAT3)has been strongly associated with tumor progression,through numerous means.Hence this allows STAT3 to be an important ta...OBJECTIVE In prostate cancer(PCa),signal transducer and activator of transcription factor3(STAT3)has been strongly associated with tumor progression,through numerous means.Hence this allows STAT3 to be an important target for therapeutic action.Artesunate(ART),a well know antimalarial agentis making its way as an anticancer drug.In the present study,we investigated whether ART can control aberrant STAT3 signaling,and thereby take a toll on PCa development.METHODS Various PCa cell lines(DU145,PC3,LNCaP)and in vivo xenograft mouse model are used.Cytotoxic effects of ART against various PCa cell lines were evaluated by MTT assay.Flow cytometry cell cycle analysis and DNA fragmentation assay was done to detect the apoptotic effect of ART.Expression of STAT3 and its regulated gene in the presence and absence of ART were measured by WB,IHC and RT PCR.STAT3 DNA binding activities was analyzed by ELISA.RESULTS ART was found to dephosphorylate STAT3 at Tyr 405,thereby reducing its nuclear translocation and DNA binding efficiency in DU145 PCa cells.We proclaim that ART can prevent the PCa development,as it can inhibit proliferation,bring about cell cycle arrest at G0/G1 phase,AnnexinⅤ positive staining,DNA fragmentation,caspase 3activation and PARP cleavage in PCa cell lines.Furthermore,inhibition of constitutive STAT3 expression was associated with the ability of ART to suppress its upstream kinases such as Janus kinase 1and 2(JAK1and JAK2).SHP-1,protein tyrosine phosphatases which are considered to be one of the major regulators of STAT3 phosphorylation was upregulated in the presence of ART.We observed reversal in ART mediated inhibition of STAT3 in the presence of pervanadate,tyrosine phosphates inhibitor and during SHP-1 knock down.ART was able to inactivate STAT3 in DU145 cells exposed to conditioned media(CM)rich in cytokines.In the presence of ART we observed the down regulation of various STAT3 regulated gene products which are involved in proliferation,survival,and angiogenesis.ART even blocked the motility and invasion of PCa cells.ART substantially decreased the tumor volume in xenograft mouse which is implanted with DU145 cells.Also ability of ART to control aberrant STAT3 signaling was in accordance with its invitrostudies.CONCLUSION Over all through our findings,we have disclosed for the first time that ART could possibly exerts it antitumor effect by interrupting deregulated expression of STAT3 in PCa,both in vitro and in vivo.展开更多
基金The project supported by grants from the Academic Research Fund Tier 1(R-184-000-228-112)the Cancer Science Institute of Singapore,Experimental Therapeutics I Program(grant R-713-001-011-271)
文摘OBJECTIVE To evaluate if RNA helicase DDX20,highly expressed in triple negative breast cancer(TNBC)cells,could serve as a surrogate marker for simvastatin treatment response.METHODS We first assessed correlation between 17 mevalonate pathway-related genes and expression of DDX20 in a cohort of 1325 breast cancer tumors.TNBC cells,MDA-MB-231,were then treated with simvastatin and mevalonate pathway intermediates to assess the alteration in DDX20 expression.In the mouse model,MDA-MB-231 cells were injected to tail veins of mice,groups of 8mice each were injected intraperioneally with vehicle or simvastatin 25mg·kg-1 3times a week for 6weeks.The number of metastatic colonies formed was quantified and immunohistochemical(IHC)staining of DDX20 was carried out in the lung tissues.RESULTS Among the 17 genes evaluated,positive correlation with DDX20 expression was observed in eight of them,with HMGCR having the highest correlation.Our in vitro experiments show exposure of breast cancer cells to simvastatin lead to a Rho-dependent decrease in gene expression of DDX20,leading to decreased tumor proliferation in a mevalonate pathway-dependent manner.Conversely,ectopic overexpression of DDX20 significantly abrogated the anti-metastatic activity of simvastatin.A similar observation is seen in the mouse model,where simvastatin-injected mice show significantly fewer visible lung metastases compared to placebo-fed mice.IHC staining on these lung tissues showed decreased DDX20 expression in simvastatin-injected group,corroborating our observations in vitro.CONCLUSION DDX20 is a potential surrogate marker for simvastatin treatment response in breast cancer and a long term implication of our findings is the possibility of an effective combinatorial therapeutic intervention using statins(to suppress DDX20 gene expression)and a suitable firstline agent″for the kill″of invasive breast cancer.
基金The project supported in part by agrant from National Medical Research Council of Singapore
文摘OBJECTIVE Doxorubicin-based therapy has been found to be not significantly effective for the treatment of advanced stage hepatocellular carcinomas(HCCs),which often undergo epithelial-mesenchymal transition(EMT)during tumor progression.Increasing evidence suggest(s)that epithelial cell transformation to mesenchymal state canenhance the ability to self-renew and confer greater resistance to the conventional chemotherapeutic drugs.The aim of this study was to examine the potential efficacyof ascochlorin,an isoprenoid antibiotic to overcome drug resistance induced by doxorubicin in HCC cell lines and to elucidate its underlying mechanism(s)of action.METHODS The effect of doxorubicin and ascochlorin on HCC cell lines was determined by MTT,Western blotting,immunofluorescence and NF-кB DNA binding assays.RESULTS Our results indicate that HCC cells that show a mesenchymal-like phenotype,are resistance to the doxorubicin therapy which directly correlated with an increased slug expression.We also observed that activation of NF-кB pathway plays an essential role in doxorubicin induced-chemoresistance and pharmacological inhibition of this pathway with ascochlorin can significantly reverse drug-induced invasion/migration and resistance in HCC cells.CONCLUSION Our results indicate that combination treatment of doxorubicin with ascochlorin has the potential to inhibit HCC growth and metastasis.
文摘OBJECTIVE In prostate cancer(PCa),signal transducer and activator of transcription factor3(STAT3)has been strongly associated with tumor progression,through numerous means.Hence this allows STAT3 to be an important target for therapeutic action.Artesunate(ART),a well know antimalarial agentis making its way as an anticancer drug.In the present study,we investigated whether ART can control aberrant STAT3 signaling,and thereby take a toll on PCa development.METHODS Various PCa cell lines(DU145,PC3,LNCaP)and in vivo xenograft mouse model are used.Cytotoxic effects of ART against various PCa cell lines were evaluated by MTT assay.Flow cytometry cell cycle analysis and DNA fragmentation assay was done to detect the apoptotic effect of ART.Expression of STAT3 and its regulated gene in the presence and absence of ART were measured by WB,IHC and RT PCR.STAT3 DNA binding activities was analyzed by ELISA.RESULTS ART was found to dephosphorylate STAT3 at Tyr 405,thereby reducing its nuclear translocation and DNA binding efficiency in DU145 PCa cells.We proclaim that ART can prevent the PCa development,as it can inhibit proliferation,bring about cell cycle arrest at G0/G1 phase,AnnexinⅤ positive staining,DNA fragmentation,caspase 3activation and PARP cleavage in PCa cell lines.Furthermore,inhibition of constitutive STAT3 expression was associated with the ability of ART to suppress its upstream kinases such as Janus kinase 1and 2(JAK1and JAK2).SHP-1,protein tyrosine phosphatases which are considered to be one of the major regulators of STAT3 phosphorylation was upregulated in the presence of ART.We observed reversal in ART mediated inhibition of STAT3 in the presence of pervanadate,tyrosine phosphates inhibitor and during SHP-1 knock down.ART was able to inactivate STAT3 in DU145 cells exposed to conditioned media(CM)rich in cytokines.In the presence of ART we observed the down regulation of various STAT3 regulated gene products which are involved in proliferation,survival,and angiogenesis.ART even blocked the motility and invasion of PCa cells.ART substantially decreased the tumor volume in xenograft mouse which is implanted with DU145 cells.Also ability of ART to control aberrant STAT3 signaling was in accordance with its invitrostudies.CONCLUSION Over all through our findings,we have disclosed for the first time that ART could possibly exerts it antitumor effect by interrupting deregulated expression of STAT3 in PCa,both in vitro and in vivo.
