Lukasz Hudak

The histone deacetylase inhibitor valproic acid alters growth properties of renal cell carcinoma in vitro and in vivo

Histone deacetylase (HDAC) inhibitors represent a promising class of antineoplastic agents which affect tumour growth, differentiation and invasion. The effects of the HDAC inhibitor valproic acid (VPA) were tested in vitro and in vivo on pre‐clinical renal cell carcinoma (RCC) models. Caki‐1, KTC‐26 or A498 cells were treated with various concentrations of VPA during in vitro cell proliferation 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assays and to evaluate cell cycle manipulation. In vivo tumour growth was conducted in subcutaneous xenograft mouse models. The anti‐tumoural potential of VPA combined with low‐dosed interferon‐α (IFN‐α) was also investigated. VPA significantly and dose‐dependently up‐regulated histones H3 and H4 acetylation and caused growth arrest in RCC cells. VPA altered cell cycle regulating proteins, in particular CDK2, cyclin B, cyclin D3, p21 and Rb. In vivo, VPA significantly inhibited the growth of Caki‐1 in subcutaneous xenografts, accompanied by a strong accumulation of p21 and bax in tissue specimens of VPA‐treated animals. VPA–IFN‐α combination markedly enhanced the effects of VPA monotherapy on RCC proliferation in vitro, but did not further enhance the anti‐tumoural potential of VPA in vivo. VPA was found to have profound effects on RCC cell growth, lending support to the initiation of clinical testing of VPA for treating advanced RCC.

New histone deacetylase inhibitors as potential therapeutic tools for advanced prostate carcinoma

The anti‐epileptic drug valproic acid is also under trial as an anti‐cancer agent due to its histone deacetylase (HDAC) inhibitory properties. However, the effects of valproic acid (VPA) are limited and concentrations required for exerting anti‐neoplastic effects in vitro may not be reached in tumour patients. In this study, we tested in vitro and in vivo effects of two VPA‐derivatives (ACS2, ACS33) on pre‐clinical prostate cancer models. PC3 and DU‐145 prostate tumour cell lines were treated with various concentrations of ACS2 or ACS33 to perform in vitro cell proliferation 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) assays and to evaluate tumour cell adhesion to endothelial cell monolayers. Analysis of acetylated histones H3 and H4 protein expression was performed by western blotting. In vivo tumour growth was conducted in subcutaneous xenograft mouse models. Tumour sections were assessed by immunohistochemistry for histone H3 acetylation and proliferation. ACS2 and ACS33 significantly up‐regulated histone H3 and H4 acetylation in prostate cancer cell lines. In micromolar concentrations both compounds exerted growth arrest in PC3 and DU‐145 cells and prevented tumour cell attachment to endothelium. In vivo, ACS33 inhibited the growth of PC3 in subcutaneous xenografts. Immunohistochemistry and western blotting confirmed increased histone H3 acetylation and reduced proliferation. ACS2 and ACS33 represent novel VPA derivatives with superior anti‐tumoural activities, compared to the mother compound. This investigation lends support to the clinical testing of ACS2 or ACS33 for the treatment of prostate cancer.

Inhibitory effects of the HDAC inhibitor valproic acid on prostate cancer growth are enhanced by simultaneous application of the mTOR inhibitor RAD001

AIMS To analyze the combined impact of the histone deacetylase (HDAC) inhibitor valproic acid (VPA) and the mammalian target of rapamycin (mTOR) inhibitor RAD001 on prostate cancer cell growth. MAIN METHODS PC-3, DU-145 and LNCaP cells were treated with RAD001, VPA or with an RAD001-VPA combination for 3 or 5 days. Tumor cell growth, cell cycle progression and cell cycle regulating proteins were then investigated by MTT assay, flow cytometry and Western blotting, respectively. Effects of drug treatment on cell signaling pathways were determined. KEY FINDINGS Separate application of RAD001 or VPA distinctly reduced tumor cell growth and impaired cell cycle progression. Significant additive effects were evoked when both drugs were used in concert. Particularly, the cell cycle regulating proteins cdk1, cdk2, cdk4 and cyclin B were reduced, whereas p21 and p27 were enhanced by the RAD001-VPA combination. Signaling analysis revealed deactivation of EGFr, ERK1/2 and p70S6k. Phosphorylation of Akt was diminished in DU-145 but elevated in PC-3 and LNCaP cells. SIGNIFICANCE The RAD001-VPA combination exerted profound antitumor properties on a panel of prostate cancer cell lines. Therefore, simultaneous blockage of HDAC and mTOR related pathways should be considered when designing novel therapeutic strategies for treating prostate carcinoma.

The cdk1-cyclin B complex is involved in everolimus triggered resistance in the PC3 prostate cancer cell line

The growth potential of PC3 prostate cancer cells, sensible (PC3(par)) or resistant (PC3(res)) to the mTOR inhibitor everolimus (RAD001) was investigated. Cell growth and proliferation of PC3(res) was similar to that of PC3(par), and late apoptosis increased in PC3(par) but decreased in PC3(res) following treatment with low dosed everolimus. PC3(res) accumulated in the G2/M-phase, accompanied by cdk1, cdk2 and cyclin B elevation. Knocking down cdk1 or cyclin B distinctly blocked the growth activity of PC3(res). One reason for everolimus resistance may be up-regulation of the cdk1-cyclin B complex in prostate cancer cells, leading to enhanced progression towards G2/M.

Combining the receptor tyrosine kinase inhibitor AEE788 and the mammalian target of rapamycin (mTOR) inhibitor RAD001 strongly inhibits adhesion and growth of renal cell carcinoma cells

BackgroundTreatment options for metastatic renal cell carcinoma (RCC) are limited due to resistance to chemo- and radiotherapy. The development of small-molecule multikinase inhibitors has now opened novel treatment options. We evaluated the influence of the receptor tyrosine kinase inhibitor AEE788, applied alone or combined with the mammalian target of rapamycin (mTOR) inhibitor RAD001, on RCC cell adhesion and proliferation in vitro.MethodsRCC cell lines Caki-1, KTC-26 or A498 were treated with various concentrations of RAD001 or AEE788 and tumor cell proliferation, tumor cell adhesion to vascular endothelial cells or to immobilized extracellular matrix proteins (laminin, collagen, fibronectin) evaluated. The anti-tumoral potential of RAD001 combined with AEE788 was also investigated. Both, asynchronous and synchronized cell cultures were used to subsequently analyze drug induced cell cycle manipulation. Analysis of cell cycle regulating proteins was done by western blotting.ResultsRAD001 or AEE788 reduced adhesion of RCC cell lines to vascular endothelium and diminished RCC cell binding to immobilized laminin or collagen. Both drugs blocked RCC cell growth, impaired cell cycle progression and altered the expression level of the cell cycle regulating proteins cdk2, cdk4, cyclin D1, cyclin E and p27. The combination of AEE788 and RAD001 resulted in more pronounced RCC growth inhibition, greater rates of G0/G1 cells and lower rates of S-phase cells than either agent alone. Cell cycle proteins were much more strongly altered when both drugs were used in combination than with single drug application. The synergistic effects were observed in an asynchronous cell culture model, but were more pronounced in synchronous RCC cell cultures.ConclusionPotent anti-tumoral activitites of the multikinase inhibitors AEE788 or RAD001 have been demonstrated. Most importantly, the simultaneous use of both AEE788 and RAD001 offered a distinct combinatorial benefit and thus may provide a therapeutic advantage over either agent employed as a monotherapy for RCC treatment.

Molecular targeting of prostate cancer cells by a triple drug combination down-regulates integrin driven adhesion processes, delays cell cycle progression and interferes with the cdk-cyclin axis

BackgroundSingle drug use has not achieved satisfactory results in the treatment of prostate cancer, despite application of increasingly widespread targeted therapeutics. In the present study, the combined impact of the mammalian target of rapamycin (mTOR)-inhibitor RAD001, the dual EGFr and VGEFr tyrosine kinase inhibitor AEE788 and the histone deacetylase (HDAC)-inhibitor valproic acid (VPA) on prostate cancer growth and adhesion in vitro was investigated.MethodsPC-3, DU-145 and LNCaP cells were treated with RAD001, AEE788 or VPA or with a RAD-AEE-VPA combination. Tumor cell growth, cell cycle progression and cell cycle regulating proteins were then investigated by MTT-assay, flow cytometry and western blotting, respectively. Furthermore, tumor cell adhesion to vascular endothelium or to immobilized extracellular matrix proteins as well as migratory properties of the cells was evaluated, and integrin α and β subtypes were analyzed. Finally, effects of drug treatment on cell signaling pathways were determined.ResultsAll drugs, separately applied, reduced tumor cell adhesion, migration and growth. A much stronger anti-cancer effect was evoked by the triple drug combination. Particularly, cdk1, 2 and 4 and cyclin B were reduced, whereas p27 was elevated. In addition, simultaneous application of RAD001, AEE788 and VPA altered the membranous, cytoplasmic and gene expression pattern of various integrin α and β subtypes, reduced integrin-linked kinase (ILK) and deactivated focal adhesion kinase (FAK). Signaling analysis revealed that EGFr and the downstream target Akt, as well as p70S6k was distinctly modified in the presence of the drug combination.ConclusionsSimultaneous targeting of several key proteins in prostate cancer cells provides an advantage over targeting a single pathway. Since strong anti-tumor properties became evident with respect to cell growth and adhesion dynamics, the triple drug combination might provide progress in the treatment of advanced prostate cancer.

HDAC inhibition delays cell cycle progression of human bladder cancer cells in vitro.

Our aim was to analyze the impact of the histone deacetylase (HDAC)-inhibitor valproic acid (VPA) on bladder cancer cell growth in vitro. RT-4, TCCSUP, UMUC-3, and RT-112 bladder cancer cells were treated with VPA (0.125–1 mmol/l) without and with preincubation periods of 3 and 5 days. Controls remained untreated. Tumor cell growth, cell cycle progression, and cell cycle-regulating proteins were investigated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, flow cytometry, and western blotting, respectively. Effects of VPA on histone H3 and H4 acetylation and HDAC3 and HDAC4 were also determined. Without preincubation, no tumor cell growth reduction was observed with 0.125 and 0.25 mmol/l VPA in TCCSUP, UMUC-3, and RT-112 cells, whereas 0.5 and 1 mmol/l VPA diminished the cell number significantly. VPA (0.25 mmol/l) did exert tumor growth-blocking effects after a 3-day preincubation. To achieve antitumor effects with VPA (0.125 mmol/l), a 5-day preincubation was necessary. A 3-day or 5-day preincubation was also necessary to distinctly delay cell cycle progression, with maximum effects at VPA (1 mmol/l). After the 5-day preincubation, the cell cycle-regulating proteins cdk1, cdk2, cdk4, and cyclins B, D1, and E were reduced, whereas p27 was enhanced. Diminished HDAC3 and 4 expression induced by VPA was accompanied by elevated acetylation of H3 and H4. VPA exerted growth-blocking properties on a panel of bladder cancer cell lines, commensurate with dose and exposure time. Long-term application induced much stronger effects than did shorter application and should be considered when designing therapeutic strategies for treating bladder carcinoma.

Effects of combined valproic acid and the epidermal growth factor/vascular endothelial growth factor receptor tyrosine kinase inhibitor AEE788 on renal cell carcinoma cell lines in vitro

To evaluate adhesion and growth inhibiting effects of the multiple receptor tyrosine kinase inhibitor AEE788 and the histone deacetylase (HDAC) inhibitor valproic acid (VPA) on renal cell carcinoma (RCC) cells.

Effects of electrical stimulation on rat limb regeneration, a new look at an old model

Limb loss is a devastating disability and while current treatments provide aesthetic and functional restoration, they are associated with complications and risks. The optimal solution would be to harness the body’s regenerative capabilities to regrow new limbs. Several methods have been tried to regrow limbs in mammals, but none have succeeded. One such attempt, in the early 1970s, used electrical stimulation and demonstrated partial limb regeneration. Several researchers reproduced these findings, applying low voltage DC electrical stimulation to the stumps of amputated rat forelimbs reporting “blastema, and new bone, bone marrow, cartilage, nerve, skin, muscle and epiphyseal plate formation”. In spite of these encouraging results this research was discontinued. Recently there has been renewed interest in studying electrical stimulation, primarily at a cellular and subcellular level, and studies have demonstrated changes in stem cell behavior with increased proliferation, differentiation, matrix formation and migration, all important in tissue regeneration. We applied electrical stimulation, in vivo, to the stumps of amputated rat limbs and observed significant new bone, cartilage and vessel formation and prevention of neuroma formation. These findings demonstrate that electricity stimulates tissue regeneration and form the basis for further research leading to possible new treatments for regenerating limbs.

Low dosed interferon alpha augments the anti-tumor potential of histone deacetylase inhibition on prostate cancer cell growth and invasion.

We evaluated whether low‐dosed interferon alpha (IFNa) may augment the anti‐tumor potential of the histone deacetylase (HDAC)‐inhibitor valproic acid (VPA) on prostate cancer cells in vitro and in vivo. PC‐3, DU‐145, or LNCaP prostate cancer cells were treated with VPA (1 mM), IFNa (200 U/ml), or with the VPA‐IFNa combination. Tumor cell growth, cell cycle progression, and cell cycle regulating proteins were then investigated by the MTT assay, flow cytometry, and western blotting. Tumor cell adhesion to endothelium or to immobilized extracellular matrix proteins, as well as migratory properties of the cells, were evaluated. Integrin α and β adhesion molecules and alterations of cell signaling pathways were analyzed. Finally, effects of the drug treatment on prostate cancer growth in vivo were determined in the NOD/SCID mouse model. VPA reduced tumor cell adhesion, migration, and growth in vitro. A much stronger anti‐cancer potential was evoked by the VPA‐IFNa combination, although IFNa in itself did not block growth or adhesion. The same effect was seen when tumor growth was evaluated in vivo. Molecular analysis revealed distinct elevation of histone H3 acetylation caused by VPA which was further up‐regulated by VPA‐IFNa, whereas IFNa alone did not alter H3 acetylation. The combinatorial benefit became obvious in Akt phosphorylation, p21 and p27 and integrin α1, α3, and β1 expression. Application of low‐dosed IFNa to a VPA based regimen profoundly boosts the anti‐tumor properties of VPA. The combined use of VPA and low‐dosed IFNa may therefore be an innovative option in treating advanced prostate cancer. Prostate 72:1719–1735, 2012.