Histone Deacetylase Inhibitor PXD101 Research Articles

Evaluation of the effects of histone deacetylase inhibitor PXD-101 on osteosarcoma cell lines

Evaluation of the effects of histone deacetylase inhibitor PXD-101 on osteosarcoma cell lines

Effects of PXD101 and Embryo Aggregation on the In Vitro Development of Mouse Parthenogenetic Embryos.

To improve the isolation efficiency of parthenogenetic embryonic stem cells (pESCs) in mice, it is necessary to optimize the method to increase in vitro developmental competence of mice parthenogenetic blastocysts. Therefore, this study aims to investigate an optimal method for the production of mouse parthenogenetic blastocysts and isolation of pESC colonies by comparing the effects of two methods: (1) the treatment of histone deacetylase inhibitor PXD101 before, during, or after parthenogenetic activation; (2) parthenogenetic embryo aggregation; and (3) their combination treatment. The results suggest that application of PXD101 treatment and embryo aggregation could both improve the development of mouse parthenogenetic blastocysts (50 nM PXD101 treated 4 hours during activation and further 4 hours after activation: 40.0% vs. 20.0%; p < 0.05; two-cell embryo aggregation: 38.3% vs. 20.0%; p < 0.05) and also enhance the isolation rate of pESC colonies (PXD101: 33.3% vs. 11.8%; p < 0.05; two-cell embryo aggregation: 36.4% vs. 11.8%; p < 0.05). The combination of their treatments had the higher rate of parthenogenetic blastocyst development (41.7%) and significantly higher rate of pESC colony isolation from parthenogenetic blastocysts (45.0%); therefore, we concluded that the combination of these two methods (50 nM PXD101 treated for 8 hours and then aggregated at two-cell stage with 0.25% pronase for 10 minutes in our self-made concave) is considered the optimal way for the in vitro development of parthenogenetic blastocysts and subsequent pESC colony isolation in mice, opening new opportunities for application of this combination method to improve the parthenogenetic embryo development in other species.

Gemigliptin, a novel dipeptidyl peptidase-IV inhibitor, exerts a synergistic cytotoxicity with the histone deacetylase inhibitor PXD101 in thyroid carcinoma cells.

The influence of the dipeptidyl peptidase-IV inhibitor gemigliptin alone or in combination with the histone deacetylase inhibitor PXD101 on survival of thyroid carcinoma cells was investigated. SW1736, TPC-1, 8505C and BCPAP human thyroid carcinoma cells were used. To assess cell survival, cell viability, the percentage of viable cells and dead cells, cytotoxic activity, ATP levels and FACS analysis were measured. To validate the impact of gemigliptin combined with PXD101, the interactions were estimated by obtaining combination index in cells treated with two agents. In cells treated with gemigliptin or PXD101, cell viability, the percentage of viable cells and ATP levels were reduced, and the percentage of dead cells and cytotoxic activity were elevated. In cells treated with both gemigliptin and PXD101, compared with PXD101 alone, cell death was augmented, and all of the combination index values were lower than 1.0, suggesting the synergism between gemigliptin and PXD101. The percentage of apoptotic cells, and the protein levels of Bcl2 and cleaved poly (ADP-ribose) polymerase were elevated, and the protein levels of xIAP and survivin were reduced. The protein levels of phospho-Akt and phospho-AMPK were elevated, and cell migration was reduced. Our results demonstrate that gemigliptin induces cytotoxicity in thyroid carcinoma cells. Moreover, gemigliptin has a synergistic activity with PXD101 in the induction of cell death through involvement of Bcl2 family proteins, xIAP and survivin as well as mediation of Akt and AMPK in thyroid carcinoma cells.

Effects of Embryo Aggregation and PXD101 on the In Vitro Development of Mouse Somatic Cell Nuclear Transfer Embryos.

To improve the cloning efficiency of somatic cell nuclear transfer (SCNT) and to establish nuclear transfer embryonic stem cells (NT-ESCs) reliably, it is necessary to produce high-quality blastocysts derived from mice SCNT embryos. Therefore, the present study aims to investigate an optimal method for mouse SCNT embryo production and NT-ESCs derivation by comparing the effects of two methods: the treatment of histone deacetylase inhibitor PXD101 after SCNT, embryo aggregation and their combination treatment. The results suggest that embryo aggregation at four-cell stage and 50 nM PXD101 treated for 10 hours during and after activation could improve both mouse SCNT embryos' development (PXD101: 40.0% vs. 18.5%; p < 0.05; aggregation: 40.2% vs. 18.5%; p < 0.05) and also enhance the isolation rate of NT-ESCs (PXD101: 38.2% vs. 12.5%; p < 0.05; aggregation: 39.0% vs. 12.5%; p < 0.05). The combination of their treatments had a higher development rate (43.6%) and significantly higher NT-ESCs isolation rate (54.7%), therefore, we concluded that the combination of these two methods (50 nM PXD101 treated for 10 hours after SCNT and then aggregated at four-cell stage) is considered as the optimal way for the in vitro development of SCNT embryo and subsequent NT-ESCs isolation in mice, providing a new approach for the practical improvement of mouse cloning techniques and opening new opportunities to improve cloning efficiencies in other species.

PXD101 significantly improves nuclear reprogramming and the in vitro developmental competence of porcine SCNT embryos

In this study, we investigated the effects of the histone deacetylase inhibitor PXD101 (belinostat) on the preimplantation development of porcine somatic cell nuclear transfer (SCNT) embryos and their expression of the epigenetic markers histone H3 acetylated at lysine 9 (AcH3K9). We compared the in vitro developmental competence of SCNT embryos treated with various concentrations of PXD101 for 24h. Treatment with 0.5μM PXD101 significantly increased the proportion of SCNT embryos that reached the blastocyst stage, in comparison to the control group (23.3% vs. 11.5%, P<0.05). We tested the in vitro developmental competence of SCNT embryos treated with 0.5μM PXD101 for various amounts of times following activation. Treatment for 24h significantly improved the development of porcine SCNT embryos, with a significantly higher proportion of embryos reaching the blastocyst stage in comparison to the control group (25.7% vs. 10.6%, P<0.05). PXD101-treated SCNT embryos were transferred into two surrogate sows, one of whom became pregnant and four fetuses developed. PXD101 treatment significantly increased the fluorescence intensity of immunostaining for AcH3K9 in embryos at the pseudo-pronuclear and 2-cell stages. At these stages, the fluorescence intensities of immunostaining for AcH3K9 were significantly higher in PXD101-treated embryos than in control untreated embryos. In conclusion, this study demonstrates that PXD101 can significantly improve the in vitro and in vivo developmental competence of porcine SCNT embryos and can enhance their nuclear reprogramming.

Novel heat shock protein 90 inhibitor NVP-AUY922 synergizes with the histone deacetylase inhibitor PXD101 in induction of death of anaplastic thyroid carcinoma cells.

The influence of the novel heat shock protein 90 (hsp90) inhibitor NVP-AUY922 (AUY922) on anaplastic thyroid carcinoma (ATC) cells has not been investigated. The effect of AUY922 alone or in combination with the histone deacetylase inhibitor PXD101 on survival of ATC cells was evaluated. In ATC cells, AUY922, compared with 17-allylamino-17-demethoxygeldanamycin, herbimycin A and radicicol, potently lead to growth inhibition and cell death with cleavage of caspase-3 and poly (ADP-ribose) polymerase (PARP) and concomitant changes in expression of hsp90 client proteins. After treatment of both AUY922 and PXD101, compared with treatment of AUY922 or PXD101 alone, the percentage of nonviable cells, annexin V-stained cells, and cytotoxic activity increased. All of the combination index values were lower than 1.0, suggesting the synergism between AUY922 and PXD101 in induction of cell death. In cells treated with both AUY922 and PXD101, compared with cells treated with AUY922 alone, the protein levels of phospho-Akt, cellular inhibitor of apoptosis protein, X-linked inhibitor of apoptosis protein, survivin, ataxia telangiectasia mutated (ATM), and ATM and Rad-3 related (ATR) decreased, whereas those of acetyl. histone H3, acetyl. histone H4, phospho-histone H2A.X, cleaved DFF45, and cleaved PARP increased. Our results demonstrate that AUY922 potently induces cytotoxicity with concomitant modulation of hsp90 client proteins in ATC cells. Moreover, AUY922 has a synergistic activity with PXD101 in induction of cytotoxicity in conjunction with the inactivation of PI3K/Akt signaling and survivin and the activation of DNA damage response in ATC cells.

Utility of a Histone Deacetylase Inhibitor (PXD101) for Thyroid Cancer Treatment

BackgroundWe evaluated the therapeutic effects of the histone deacetylase inhibitor PXD101 alone and in combination with conventional chemotherapy in treating thyroid cancer.Methodology/Principal FindingsWe studied eight cell lines from four types of thyroid cancer (papillary, follicular, anaplastic and medullary). The cytotoxicity of PXD101 alone and in combination with three conventional chemotherapeutic agents (doxorubicin, paclitaxel and docetaxel) was measured using LDH assay. Western blot assessed expression of acetylation of histone H3, histone H4 and tubulin, proteins associated with apoptosis, RAS/RAF/ERK and PI3K/AKT/mTOR signaling pathways, DNA damage and repair. Apoptosis and intracellular reactive oxygen species (ROS) were measured by flow cytometry. Mice bearing flank anaplastic thyroid cancers (ATC) were daily treated with intraperitoneal injection of PXD101 for 5 days per week. PXD101 effectively inhibited thyroid cancer cell proliferation in a dose-dependent manner. PXD101 induced ROS accumulation and inhibited RAS/RAF/ERK and PI3K/mTOR pathways in sensitive cells. Double-stranded DNA damage and apoptosis were induced by PXD101 in both sensitive and resistant cell lines. PXD101 retarded growth of 8505C ATC xenograft tumors with promising safety. Combination therapy of PXD101with doxorubicin and paclitaxel demonstrated synergistic effects against four ATC lines in vitro.ConclusionsPXD101 represses thyroid cancer proliferation and has synergistic effects in combination with doxorubicin and paclitaxel in treating ATC. These findings support clinical trials using PXD101 for patients with this dismal disease.

The histone deacetylase inhibitor PXD101 increases the efficacy of irinotecan in in vitro and in vivo colon cancer models

Histone deacetylase inhibitors (HDACIs), such as PXD101 and suberoylanilide hydroxamic acid, inhibit proliferation and stimulate apoptosis of tumor cells. The enhanced effectiveness of chemotherapy or radiotherapy when combined with HDACIs has been observed in several cancers. In this study, we investigated the antitumor effect of PXD101 combined with irinotecan in colon cancer. HCT116 and HT29 colon cancer cells for cell viability assay were treated with PXD101 and/or SN-38, the active form of irinotecan. Antitumor effects of HCT116 and HT29 xenografts treated with these combinations were evaluated. [(18)F]FLT-PET was used to detect early responses to PXD101 and irinotecan in colon cancer. PXD101 and SN38 possessed dose-dependent antiproliferative activity against HCT116 and HT29 cells and exerted a synergistic effect when used in combination. In xenografted mice, PXD101 in combination with irinotecan dramatically inhibited tumor growth without causing additive toxicity. Apoptotic effects on xenograft tumors were greater with combined treatment than with irinotecan alone. [(18)F]FLT-PET imaging revealed a 64% decrease in [(18)F]FLT uptake in tumors of HCT116 xenograft-bearing mice treated with a combination of PXD101 and irinotecan, indicating a decrease in thymidine kinase 1 (TK1) activity. These results were supported by Western blot analyses showing a decrease in tumor thymidine kinase 1 protein levels, suggesting that [(18)F]FLT-PET can be used to non-invasively detect early responses to these agents. These data show that PXD101 increases the cytotoxic activity of irinotecan in in vitro and in vivo colon cancer models and suggest these agent combinations should be explored in the treatment of colon cancer.

The preclinical activity of the histone deacetylase inhibitor PXD101 (belinostat) in hepatocellular carcinoma cell lines

The activity of the histone deacetylase inhibitor PXD101 was investigated in three hepatocellular carcinoma (HCC) cell lines. PXD101 was found to inhibit cell growth at a dose-dependent manner and induce histone acetylation in PLC/PRF/5, Hep3B and HepG2 cells. In PLC/PRF/5 and Hep3B cells which express hepatitis B-related genes (HBx, HBc and HBc), treatment with PXD101 resulted in apoptosis without a significant effect on viral gene expression. Exposure to PXD101 for up to 48 h had varying effects on the expression of 12 cellular genes with tumor suppressor functions, including p21, SOCS1, CMTM5, RASAL1, DLEC1, SFRP (-1, -2, -4 and -5), ADAMTS (-8 and -9). This study provided the basis for a phase II clinical trial of PXD101 in inoperable hepatitis-B associated HCC.

Nuclear factor-κB p65 small interfering RNA or proteasome inhibitor bortezomib sensitizes head and neck squamous cell carcinomas to classic histone deacetylase inhibitors and novel histone deacetylase inhibitor PXD101

Histone deacetylase inhibitors (HDI) can inhibit proliferation and enhance apoptosis in a wide range of malignancies. However, HDIs show relatively modest activity in head and neck squamous cell carcinomas (HNSCC), in which we have shown the activation of nuclear factor-kappaB (NF-kappaB; NF-kappaB1/RelA or p50/p65), a transcription factor that promotes expression of proliferative and antiapoptotic genes. In this study, we examined if HDIs enhance activation of NF-kappaB and target genes and if genetic or pharmacologic inhibition of NF-kappaB can sensitize HNSCC to HDIs. Limited activity of classic HDIs trichostatin A and sodium butyrate was associated with enhanced activation of NF-kappaB reporter activity in a panel of six HNSCC cell lines. HDIs enhanced NF-kappaB p50/p65 DNA binding and acetylation of the RelA p65 subunit. Transfection of small interfering RNAs targeting p65 strongly inhibited NF-kappaB expression and activation, induced cell cycle arrest and cell death, and further sensitized HNSCC cells when combined with HDIs. The p65 small interfering RNA inhibited HDI-enhanced expression of several NF-kappaB-inducible genes implicated in oncogenesis of HNSCC, such as p21, cyclin D1, and BCL-XL. Bortezomib, an inhibitor of proteasome-dependent NF-kappaB activation, also increased sensitization to trichostatin A, sodium butyrate, and a novel HDI, PXD101, in vitro, and to the antitumor effects of PXD101 in bortezomib-resistant UMSCC-11A xenografts. However, gastrointestinal toxicity, weight loss, and mortality of the combination were dose limiting and required parenteral fluid administration. We conclude that HDI-enhanced NF-kappaB activation is one of the major mechanisms of resistance of HNSCC to HDIs. The combination of HDI and proteasome inhibitor produced increased antitumor activity. Low starting dosages for clinical studies combining HDIs with proteasome inhibitors and IV fluid support may be warranted.

The histone deacetylase inhibitor PXD101 synergises with 5-fluorouracil to inhibit colon cancer cell growth in vitro and in vivo

Histone deacetylase inhibitors (HDACi) inhibit the growth of cancer cells, and combinations of HDACi with established chemotherapeutics can lead to synergistic effects. We have investigated effects of PXD101 (HDACi in phase II clinical trials) in combination with 5-fluorouracil, on tumour cell proliferation and apoptosis both in vitro and in vivo. HCT116 cells were studied using proliferation and clonogenic assays. Synergistic inhibition of proliferation and clonogenicity was determined by incubation with PXD101 and 5-fluorouracil, and analysis using CalcuSyn software. The effect of combining PXD101 and 5-fluorouracil on apoptosis was examined in vitro using PARP-cleavage and TUNEL. Finally, the effectiveness of combining PXD101 and 5-fluorouracil in vivo was tested using both HT-29 and HCT116 xenograft models. Synergistic inhibition of proliferation and clonogenicity was obtained when HCT116 cells were incubated with PXD101 and 5-fluorouracil. 5-fluorouracil combined with PXD101 also increased DNA fragmentation and PARP cleavage in HCT116 cells. Incubation with PXD101 down regulated thymidylate synthase expression in HCT116 cells. In vivo studies, using mouse HT29 and HCT116 xenograft models, showed improved reductions in tumour volume compared to single compound, when PXD101 and 5-fluorouracil were combined. PXD101 and 5-fluorouracil synergistically combine in their anti-tumour effects against colon cancer cells in vitro and show enhanced activity when combined in vivo. Based on the results presented herein, a rationale for the use of PXD101 and 5-fluorouracil in combination in the clinic has been demonstrated.

Combination of the Proteasome Inhibitor Bortezomib and a Histone Deacetylase Inhibitor PXD101 Results in Synergistic Inhibition of Osteoclastogenesis and Significantly Stronger Inhibition of Multiple Myeloma Growth In Vitro and In Vivo.

Bortezomib, a proteasome inhibitor, has been known to have in vitro and in vivo activity against multiple myeloma (MM). PXD101, a novel, low molecular weight histone deacetylase (HDAC) inhibitor recently has been recognized to induce growth arrest and apoptosis in MM cells. We hypothesized that these two agents, with different molecular targets, can be combined with a high probability of additive or synergistic effects without exerting cross-resistance.In this study, we investigated the activity of the combination of PXD101 and bortezomib against osteoclast generation and MM cell growth. To evaluate the effects of bortezomib and PXD101 on the formation of osteoclasts from mononuclear hematopoietic precursors, we generated osteoclasts cultured from human bone marrow cells from healthy donors and MM patients using in vitro RANKL/M-CSF stimulation. Proliferation of MM cell lines treated with PXD101, bortezomib, or their combination was determined by measuring 3H-Thymidine incorporation. Annexin V-FITC/PI staining was used to determine the degree of apoptosis, and trypan blue was used to assess cell viability. We utilized a xenograft murine model to test the in vivo synergistic activity of the two agents against MM tumor formation.We found that even though either drug alone significantly inhibited osteoclast formation at concentrations of PXD101 at 25 nM or bortezomib at 1 nM, the combination resulted in synergistic inhibition in osteoclast assays. Treatment of MM cells lines (MM.1S, RPMI-8226, OPM2) with serial dilutions (10–100 nM) of the combination also led to significantly stronger inhibition of proliferation, apoptosis and cell death than single drug treatment. In addition, the combination demonstrated synergistic induction of cell death in primary human CD138+ myeloma cells isolated from patient samples. In vivo, the combination of PXD101 and bortezomib resulted in significantly higher xenograft tumor inhibition compared to either drug treatment alone and was not more toxic.The current study provides the rationale for clinical evaluation of this novel PXD101-bortezomib combination for patients with MM. The data generated here support the hypothesis that simultaneous targeting of different proliferative and anti-apoptotic pathways both in tumor cells and activated osteoclasts avoids cross-resistance and constitutes a dynamic approach to treat MM.

A phase 1 pharmacokinetic (PK) and pharmacodynamic (PD) study of the histone deacetylase (HDAC) inhibitor PXD101 in patients (pts) with advanced solid tumours

3035 BackgroundPXD101 is a novel HDAC inhibitor with potent antiproliferative activity in vitro. PXD101 inhibits tumour growth in vivo in pre-clinical models. We present a phase 1 trial of PXD101 in pts with advanced solid tumours re fractory to standard therapy. Methods Sequential cohorts of 3–6 pts were recruited to this study to determine the maximum tolerated dose of PXD101 administered as a 30 minute IV infusion on days 1 - 5 of a 21 day cycle. The PK profile of PXD101 was calculated by non-compartmental analysis of plasma and urine from 2–4 pts at each dose level. Acetylation of histones extracted from PMN cells was measured by Western blotting. The PK profile of a single oral dose of PXD101 was evaluated in 3 pts. Results 21 pts (median age 58 years, range 39–72); 10M 11F; all ECOG PS ≤ 2) have been treated with a total of 57 cycles of PXD101 (median 2; range 1 to 7) at 5 escalating dose levels: 150mg/m2(4pts), 300 mg/m2(4pts), 600 mg/m2 (6pts), 900 mg/m2 (3pts) and 1200mg/m2 (3pts). No haematological toxicity was observed. Dose limiting toxicity was seen in 3 pts: G3 fatigue (1 pt) at 600 mg/m2, reversible atrial fibrillation (1 pt) at 1200 mg/m2and G3 diarrhoea and lethargy (1pt) at 1200mg/m2. All other adverse effects were ≤ G2. PXD101 displays linear kinetics. Dose-proportional Cmax (range 2.1 - 68.1μg/ml) was reached at the end of the infusion. The elimination half-life of 0.5–1 hr was independent of dose. PXD101 was detected in plasma at low levels after 10 hrs at 1200 mg/m2but undetectable after 8–10 hrs at lower doses. There was no drug accumulation on repeated dosing. Mean oral bioavailability of PXD101 was 33% (range 32–35%). Histone H4 hyperacetylation was observed at the end of each infusion and was sustained for 4–24 hrs in a dose-dependent manner. PXD101 induced p21, p19 and Apaf-1 expression in PMN cells. To date, stable disease has been achieved in 3pts for 2 cycles; 2pts for 4 cycles and 2 pts for 6 cycles. ConclusionsThe novel HDAC inhibitor PXD101 is well tolerated and exhibits dose-dependent PD effects. 1200mg/m2 was the maximally administered dose and dose escalation has ceased. Recruitment to a 1000mg/m2 dose level continues. Further studies of oral PXD101 are planned. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Topotarget Topotarget Topotarget

A phase I study of the histone deacetylase (HDAC) inhibitor PXD101 in patients with advanced hematological tumors

3137 Background PXD101 is a novel hydroxamate HDAC inhibitor with potent antiproliferative activity in vitro against many different neoplastic cell lines including myeloma and leukemia/ lymphoma lines. PXD101 inhibits tumor growth in vivo in pre-clinical models and is generally well tolerated. A phase 1 trial of intravenous PXD101 treatment in patients with advanced solid tumors proved PXD101 to be clinically well tolerated at doses leading to prolonged pharmacodynamic effects such as acetylation of circulating white blood cells. We now present a Phase 1 trial of PXD101 in patients with advanced hematological tumors refractory to standard therapy. Objective The objective of this study is to determine the maximum tolerated dose (MTD) of PXD101 administered as a 30-minute IV infusion on days 1 to 5 of a 21 days cycle in hematological patients. Methods Sequential cohorts of 3–6 patients were recruited for each dose level starting with 600 mg/m2, a dose level already proven to be well tolerated in patients with solid tumors. Results Two dose levels 600 mg/m2/d and 900 mg/m2/d have so far been examined (3 patients each) and recruitment to the dose level 1000 mg/m2/d is ongoing. The 6 patients have each been treated with 1–3 cycles of treatment. The adverse events related to PXD101 treatment have been of grade 1–2. The most frequent were fatigue (6/9 treatment cycles), nausea (7/9 cycles), vomiting (7/9 cycles) and diarrhoea (3/9 cycles). Further safety data will be presented. So far no significant trends indicating hematological or any other systemic toxicity has been noted. Antineoplastic activity has been observed; detailed response data will be presented. ConclusionsThe novel HDAC inhibitor PXD101 is generally well tolerated in patients with previously treated hematological neoplasms. The MTD has not yet been defined and evaluation of patients at the 1000 mg/m2 dose level continues. Further studies using an oral administration of PXD101 are planned. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration Topotarget Topotarget