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Acid ceramidase as a therapeutic target in metastatic prostate cancer.

ABSTRACT: Acid ceramidase (AC) catalyzes the hydrolysis of ceramide into sphingosine, in turn a substrate of sphingosine kinases that catalyze its conversion into the mitogenic sphingosine-1-phosphate. AC is expressed at high levels in several tumor types and has been proposed as a cancer therapeutic target. Using a model derived from PC-3 prostate cancer cells, the highly tumorigenic, metastatic, and chemoresistant clone PC-3/Mc expressed higher levels of the AC ASAH1 than the nonmetastatic clone PC-3/S. Stable knockdown of ASAH1 in PC-3/Mc cells caused an accumulation of ceramides, inhibition of clonogenic potential, increased requirement for growth factors, and inhibition of tumorigenesis and lung metastases. We developed de novo ASAH1 inhibitors, which also caused a dose-dependent accumulation of ceramides in PC-3/Mc cells and inhibited their growth and clonogenicity. Finally, immunohistochemical analysis of primary prostate cancer samples showed that higher levels of ASAH1 were associated with more advanced stages of this neoplasia. These observations confirm ASAH1 as a therapeutic target in advanced and chemoresistant forms of prostate cancer and suggest that our new potent and specific AC inhibitors could act by counteracting critical growth properties of these highly aggressive tumor cells.

SUBMITTER: Camacho L

PROVIDER: S-EPMC3622318 | biostudies-literature | 2013 May

REPOSITORIES: biostudies-literature

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Acid ceramidase as a therapeutic target in metastatic prostate cancer.

Camacho Luz L Meca-Cortés Oscar O Abad José Luis JL García Simón S Rubio Nuria N Díaz Alba A Celià-Terrassa Toni T Cingolani Francesca F Bermudo Raquel R Fernández Pedro L PL Blanco Jerónimo J Delgado Antonio A Casas Josefina J Fabriàs Gemma G Thomson Timothy M TM

Journal of lipid research 20130219 5

Acid ceramidase (AC) catalyzes the hydrolysis of ceramide into sphingosine, in turn a substrate of sphingosine kinases that catalyze its conversion into the mitogenic sphingosine-1-phosphate. AC is expressed at high levels in several tumor types and has been proposed as a cancer therapeutic target. Using a model derived from PC-3 prostate cancer cells, the highly tumorigenic, metastatic, and chemoresistant clone PC-3/Mc expressed higher levels of the AC ASAH1 than the nonmetastatic clone PC-3/S. ...[more]

PMID: 23423838

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Project description:BACKGROUND:Metastatic castration resistant prostate cancer (mCRPC) is incurable and progression after drugs that target the androgen receptor-signaling axis is inevitable. Thus, there is an urgent need to develop more effective treatments beyond hormonal manipulation. We sought to identify activated kinases in mCRPC as therapeutic targets for existing, approved agents, with the goal of identifying candidate drugs for rapid translation into proof of concept Phase II trials in mCRPC. METHODS:To identify evidence of activation of druggable kinases in these patients, we compared mRNA expression from metastatic biopsies of patients with mCRPC (n?=?101) to mRNA expression in localized prostate from TCGA and used this analysis to infer differential kinase activity. In addition, we assessed the differential phosphorylation levels for key MAPK pathway kinases between mCRPC and localized prostate cancers. RESULTS:Transcriptomic profiling of 101 patients with mCRPC as compared to patients with localized prostate cancer identified evidence of hyperactive ERK1, and whole genome sequencing revealed frequent amplifications of members of the MAPK pathway in 32% of this cohort. Next, we confirmed elevated levels of phosphorylated ERK1/2 in castration resistant prostate cancer as compared to untreated primary prostate cancer. We observed that the presence of detectable phosphorylated ERK1/2 in the primary tumor is associated with biochemical failure after radical prostatectomy independent of clinicopathologic features. ERK1 is the immediate downstream target of MEK1/2, which is druggable with trametinib, an approved therapeutic for melanoma. Trametinib elicited a profound biochemical and clinical response in a patient who had failed multiple prior treatments for mCRPC. CONCLUSIONS:We conclude that pharmacologic targeting of the MEK/ERK pathway may be a viable treatment strategy for patients with refractory metastatic prostate cancer. An ongoing Phase II trial tests this hypothesis.

Project description:BackgroundA number of studies have previously shown that the over expression of different ribosomal proteins might play an important role in cancer (i.e. S3a, L10, L16). We have previously reported that RPS2, a 33 Kda ribosomal protein was over expressed in malignant prostate cancer cell lines and in archived tumor specimens. Thus, RPS2 or other aberrantly over-expressed ribosomal proteins might promote cancer and be excellent therapeutic targets for treatment of the disease.MethodsWestern blotting and RT-PCR have been used to measure and compare the levels of expression of RPS2 in a variety of malignant prostate cancer cell lines, plus normal and benign cells lines. We have developed a 'ribozyme-like' DNAZYM-1P '10-23' motif oligonucleotide and examined whether it targets RPS2 in different cell lines by RT-PCR and Western blots. Growth and apoptosis assays were carried out to measure whether DNAZYM-1P 'knock-down' of RPS2 influenced cell proliferation or survival. We have also developed a SCID mouse tumor model with PC-3ML cells to determine whether DNAZYM-1P targeting of RPS2 compromised tumor growth and mouse survival rates in vivo.ResultsWestern blots showed that PC-3ML, LNCaP, CPTX-1532, and pBABE-cmyc stably transfected IBC-10a cells all over-expressed RPS2, whereas IBC-10a parent, NPTX-1532, and BPH-1 cells or mouse NIH-3T3 cells expressed barely detectable levels of RPS2. RT-PCR assays showed that DNAZYM-1P, which targeted RPS2, 'knocked-down' RPS2 expression in the malignant cells (i.e. PC-3ML cells) in vitro. The DNAZYM-1P also inhibited cell growth and induced apoptosis in the malignant prostate cells, but had little effect on the normal IBC-10a or NPTX-1532 cell lines. Finally, SCID mouse tumor modeling studies showed that DNAZYM-1P blocked tumor growth and metastasis by PC-3ML cells and eventually eradicated tumors following localized or systemic i.v. delivery. Mouse survival studies revealed that there was a dosage dependent increase in disease free survival rates in mice treated systemically with DNAZYM-1P (i.e. mouse survival increased from 0% to 100%).ConclusionIn sum, we have shown for the first time that therapeutic targeting of RPS2 is an excellent approach for the eradication of prostate cancer in preclinical tumor modeling studies.

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Acid ceramidase as a therapeutic target in metastatic prostate cancer.

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Acid ceramidase as a therapeutic target in metastatic prostate cancer.

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