Enhanced therapeutic effect on androgen-independent prostate cancer by depsipeptide (FK228), a histone deacetylase inhibitor, in combination with docetaxel

A glimpse into novel acylations and their emerging role in regulating cancer metastasis

Metastatic cancer is a major cause of cancer-related mortality; however, the complex regulation process remains to be further elucidated. A large amount of preliminary investigations focus on the role of epigenetic mechanisms in cancer metastasis. Notably, the posttranslational modifications were found to be critically involved in malignancy, thus attracting considerable attention. Beyond acetylation, novel forms of acylation have been recently identified following advances in mass spectrometry, proteomics technologies, and bioinformatics, such as propionylation, butyrylation, malonylation, succinylation, crotonylation, 2-hydroxyisobutyrylation, lactylation, among others. These novel acylations play pivotal roles in regulating different aspects of energy mechanism and mediating signal transduction by covalently modifying histone or nonhistone proteins. Furthermore, these acylations and their modifying enzymes show promise regarding the diagnosis and treatment of tumors, especially tumor metastasis. Here, we comprehensively review the identification and characterization of 11 novel acylations, and the corresponding modifying enzymes, highlighting their significance for tumor metastasis. We also focus on their potential application as clinical therapeutic targets and diagnostic predictors, discussing the current obstacles and future research prospects.

Ultrasound image features of intravesical prostatic protrusion indicated failure of medication therapy of finasteride and doxazosin in patients with benign prostatic hyperplasia (LUTS/BPH)

BACKGROUND

Intravesical prostatic protrusion (IPP) is a type of benign prostatic hyperplasia (BPH) adenoma, and it plays a critical role in the pathogenesis of bladder outlet obstruction in patients with lower urinary tract syndromes (LUTS/BPH).

AIMS

The goal of this study was to investigate the effect of a combination therapy with finasteride and doxazosin on IPP in BPU/LUTS patients.

METHODS

A total of 322 BPH patients with enlarged prostatic volume as well as moderate to severe symptom scores were enrolled and divided into four groups according to the degree of IPP (IPP > 10 mm, 5-10 mm, <5 mm and no IPP) in this study. Aggravated International Prostatic Symptom Score (IPSS), acute urinary retention or relevant urinary complications were considered as failure of the therapy. The degrees of IPP were recorded before and after 6 months of treatment. Student's t test and χ ² were performed between the baseline and endpoint of the therapy.

RESULTS

The results showed that the total prostate volume (TPV) and transition zone volume (TZV) of the prostate decreased significantly after 6-month combination therapy (P < 0.05), while no significant changes in IPP were observed at that point (P > 0.05). Failure rates of the medication differed significantly among the four groups.

CONCLUSIONS

The study indicated that the combination therapy using finasteride and doxazosin could not reduce the degree of IPP. LUTS/BPH patients with IPP which contributes to the failure of medication tend to have a higher risk of progression.

Epigenetic modulators as therapeutic targets in prostate cancer

Prostate cancer is one of the most common non-cutaneous malignancies among men worldwide. Epigenetic aberrations, including changes in DNA methylation patterns and/or histone modifications, are key drivers of prostate carcinogenesis. These epigenetic defects might be due to deregulated function and/or expression of the epigenetic machinery, affecting the expression of several important genes. Remarkably, epigenetic modifications are reversible and numerous compounds that target the epigenetic enzymes and regulatory proteins were reported to be effective in cancer growth control. In fact, some of these drugs are already being tested in clinical trials. This review discusses the most important epigenetic alterations in prostate cancer, highlighting the role of epigenetic modulating compounds in pre-clinical and clinical trials as potential therapeutic agents for prostate cancer management.

Histone deacetylase inhibitors in oral squamous cell carcinoma treatment

Introduction: The involvement of the histone deacetylases (HDACs) family in tumor development and progression is well demonstrated. HDAC inhibitors (HDACis) constitute a novel, heterogeneous family of highly selective anticancer agents that inhibit HDACs and present significant antitumor activity in several human malignancies, including oral squamous cell carcinoma (OSCC). Areas covered: This review summarizes the current research on the anticancer activity of HDACis against OSCC. The review also presents the molecular mechanisms of HDACis action and the existing studies evaluating their utilization in combined therapies of OSCC. Expert opinion: The currently available data support evidence that HDACis may provide new therapeutic options against OSCC, decreasing treatment side effects and allowing a more conservative therapeutic approach. Future research should be focused on in vivo and clinical evaluation of their utilization as combined therapies or monotherapies. Before HDACis can be brought into clinical practice as treatment options for OSCC, further evaluation is needed to determine their optimal dosage, the appropriate duration of treatment and whether they should be used in combination or as stand-alone therapeutics.

Prostate-cancer-targeted N-(2-hydroxypropyl)methacrylamide copolymer/docetaxel conjugates

Biodistribution, pharmacokinetics, and efficacy of prostate-cancer-targeted HPMA copolymer/DTX conjugates are evaluated in nude mice bearing prostate cancer C4-2 xenografts. PSMA-specific monoclonal antibodies 3F/11 are used as the targeting moiety. Control conjugates tumor accumulation to total background organs (heart, lung, kidney, liver, spleen and blood) accumulation increase substantially with time for the targeted conjugate, and the ratio at 48 h is 7-fold higher than that at 6 h. Preliminary evaluation of the efficacy of the conjugates in vivo show tumor growth inhibition for all HPMA copolymer/DTX conjugates.

Finding the place of histone deacetylase inhibitors in prostate cancer therapy

Histone deacetylase inhibitors (HDACIs) are showing promise as therapeutic agents for hematological malignancies and solid tumors. In the case of prostate cancer, HDACIs are effective at inhibiting proliferation and inducing apoptosis in a range of in vitro and in vivo experimental models. Recent studies have revealed that the actions of HDACIs in prostate cancer cells extend beyond regulation of histone acetylation and affect proteins involved in maintaining cellular homeostasis and tumor progression, including the androgen receptor, p21(WAF1) and VEGF. The broad spectrum of HDACI targets has allowed rational design of combinations with other therapeutic agents to target multiple pathways involved in prostate cancer progression, including angiogenesis and androgen signaling. In particular, synergistic inhibition of prostate cancer cell growth has been demonstrated using HDACIs in combination with radio- and chemo-therapy, Apo2L/TRAIL, angiogenesis inhibitors, heat-shock protein 90 inhibitors and androgen receptor antagonists. This review examines the current understanding of the actions of HDACIs in prostate cancer cells, both in a laboratory and a clinical context and discusses the potential utility of combination strategies for the treatment of prostate cancer.

Phase II trial of the histone deacetylase inhibitor romidepsin in patients with recurrent/metastatic head and neck cancer

OBJECTIVES

Patients with advanced squamous cell carcinoma of the head and neck (SCCHN) have limited treatment options. Inhibition of histone deacetylases (HDACs) represents a novel therapeutic approach warranting additional investigation in solid tumors.

METHODS

A phase II trial of single agent romidepsin, an HDAC inhibitor, was performed in 14 patients with SCCHN who provided consent for pre- and post-therapy samples of accessible tumor, blood and uninvolved oral mucosa. Romidepsin was administered at 13 mg/m(2) as a 4-h intravenous infusion on days 1, 8 and 15 of 28 day cycles, with response assessment by RECIST every 8 weeks.

RESULTS

Objective responses were not observed, although 2 heavily pretreated patients had brief clinical disease stabilization. Observed toxicities were expected, including frequent severe fatigue. Immunohistochemical analysis of 7 pre- and post-treatment tumor pairs demonstrated induction of p21(Waf1/Cip1) characteristic of HDAC inhibition, as well as decreased Ki67 staining. Exploratory microarray analyses of mucosal and tumor samples detected changes in gene expression following romidepsin treatment that were most commonly associated with regulation of transcription, cell cycle control, signal transduction, and electron transport. Treatment with romidepsin did not alter the extent of DNA methylation of candidate gene loci (including CDH1 and hMLH1) in SCCHN tumors.

CONCLUSIONS

Single agent romidepsin has limited activity for the treatment of SCCHN but can effectively achieve tumor-associated HDAC inhibition. Although tolerability of romidepsin in this setting may be limiting, further evaluation of other HDAC inhibitors in combination with active therapies may be justified.

A novel histone deacetylase inhibitor, CG200745, potentiates anticancer effect of docetaxel in prostate cancer via decreasing Mcl-1 and Bcl-XL

We synthesized a novel hydroxamate-based pan-histone deacetylase inhibitor (HDACI), CG200745 {(E)-2-(Naphthalen-1-yloxymethyl)-oct-2-enedioic acid 1-[(3-dimethylamino-propyl)-amide] 8-hydroxyamide]}. Like other inhibitors, for example vorinostat and belinostat, CG200745 has the hydroxamic acid moiety to bind zinc at the bottom of catalytic pocket. Firstly, we analyzed its inhibitory activity against histone deacetylase (HDAC) in hormone-dependent LNCaP cells and hormone-independent DU145 and PC3 cells. CG200745 inhibited deacetylation of histone H3 and tubulin as much as vorinostat and belinostat did. CG200745 also inhibited growth of prostate cancer cells, increased sub-G1 population, and activated caspase-9, -3 and -8 in LNCaP, DU145 and PC3 cells. These results indicate that CG200745 induces apoptosis. Next, we examined the effect of CG200745 on cell death induced by docetaxel in DU145 cells in vitro and in vivo. Compared to mono-treatment with each drug, pre-treatment of DU145 cells with docetaxel followed by CG200745 showed synergistic cytotoxicity, and increased the apoptotic sub-G1 population, caspase activation, and tubulin acetylation. Moreover, the combination treatment decreased Mcl-1 and Bcl-(XL). Docetaxel and CG200745 combination reduced tumor size in the DU145 xenograft model. These preclinical results show that combination treatment with docetaxel and new HDACI, CG200745, potentiated anti-tumor effect in hormone-refractory prostate cancer (HRPC) cells via activation of apoptosis.

Epigenetic regulation of prostate cancer

Prostate cancer is a commonly diagnosed cancer in men and a leading cause of cancer deaths. Whilst the underlying mechanisms leading to prostate cancer are still to be determined, it is evident that both genetic and epigenetic changes contribute to the development and progression of this disease. Epigenetic changes involving DNA hypo- and hypermethylation, altered histone modifications and more recently changes in microRNA expression have been detected at a range of genes associated with prostate cancer. Furthermore, there is evidence that particular epigenetic changes are associated with different stages of the disease. Whilst early detection can lead to effective treatment, and androgen deprivation therapy has a high response rate, many tumours develop towards hormone-refractory prostate cancer, for which there is no successful treatment. Reliable markers for early detection and more effective treatment strategies are, therefore, needed. Consequently, there is a considerable interest in the potential of epigenetic changes as markers or targets for therapy in prostate cancer. Epigenetic modifiers that demethylate DNA and inhibit histone deacetylases have recently been explored to reactivate silenced gene expression in cancer. However, further understanding of the mechanisms and the effects of chromatin modulation in prostate cancer are required. In this review, we examine the current literature on epigenetic changes associated with prostate cancer and discuss the potential use of epigenetic modifiers for treatment of this disease.

The HDAC inhibitor FK228 enhances adenoviral transgene expression by a transduction-independent mechanism but does not increase adenovirus replication

The histone deacetylase inhibitor FK228 has previously been shown to enhance adenoviral transgene expression when cells are pre-incubated with the drug. Upregulation of the coxsackie adenovirus receptor (CAR), leading to increased viral transduction, has been proposed as the main mechanism. In the present study, we found that the highest increase in transgene expression was achieved when non-toxic concentrations of FK228 were added immediately after transduction, demonstrating that the main effect by which FK228 enhances transgene expression is transduction-independent. FK228 had positive effects both on Ad5 and Ad5/f35 vectors with a variety of transgenes and promoters, indicating that FK228 works mainly by increasing transgene expression at the transcriptional level. In some cases, the effects were dramatic, as demonstrated by an increase in CD40L expression by FK228 from 0.3% to 62% when the murine prostate cancer cell line TRAMP-C2 was transduced with Ad[CD40L]. One unexpected finding was that FK228 decreased the transgene expression of an adenoviral vector with the prostate cell-specific PPT promoter in the human prostate adenocarcinoma cell lines LNCaP and PC-346C. This is probably a consequence of alteration of the adenocarcinoma cell lines towards a neuroendocrine differentiation after FK228 treatment. The observations in this study indicate that FK228 enhances adenoviral therapy by a transduction-independent mechanism. Furthermore, since histone deacetylase inhibitors may affect the differentiation of cells, it is important to keep in mind that the activity and specificity of tissue- and tumor-specific promoters may also be affected.

Adenoviral-mediated pHyde gene transfer and cisplatin additively inhibit human prostate cancer growth by enhancing apoptosis

BACKGROUND

A novel gene, rat pHyde, has been cloned by us recently. The rat pHyde was shown by the same group to have growth inhibitory effects on human prostate cancer through the induction of apoptosis.

METHODS

In this report, a human homologue, hpHyde of the rat pHyde, was cloned by cDNA libraries screening. The database search and in situ hybridization were used to map the genomic loci of hpHyde in human chromosome. The anti-prostate cancer effects of pHyde in conjunction with chemotherapy agent were analyzed by in vitro and in vivo assays using adenoviral vector expressing pHyde (AdRSVpHyde) in combination with DNA damaging chemotherapeutic agent, cisplatin, and docetaxel, respectively.

RESULTS

Database search and FISH analysis consistently indicated that hpHyde gene localizes at human chromosome 2q14. Protein sequence analysis suggests that hpHyde may be a plasma membrane protein. hpHyde is differentially expressed in various normal human tissues and organs, suggesting that hpHyde may play roles in development and differentiation. Growth suppression and induction of apoptosis were additively greater in DU145 human prostate cancer cells treated with AdRSVpHyde and cisplatin than either agent alone both in vitro and in vivo. Moreover, AdRSVpHyde and docetaxel also have a similar additively inhibitory effect on DU145 cell growth.

CONCLUSIONS

A novel gene hpHyde, the human homologue of rat pHyde, has been cloned and its genomic location in the human chromosome has been identified. Our results support the potential use of pHyde for prostate cancer gene therapy coupled with chemotherapy to improve therapeutic index.