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Purpose:Both gain-of-function enhancer of zeste homolog 2 (EZH2) mutations and inactivating histone acetyltransferases mutations, such as CREBBP and EP300, have been implicated in the pathogenesis of germinal center (GC)–derived lymphomas. We hypothesized that direct inhibition of EZH2 and histone deacetyltransferase (HDAC) would be synergistic in GC-derived lymphomas.Experimental Design:Lymphoma cell lines (n = 21) were exposed to GSK126, an EZH2 inhibitor, and romidepsin, a pan-HDAC inhibitor. Synergy was assessed by excess over bliss. Western blot, mass spectrometry, and coimmunoprecipitation were performed. A SU-DHL-10 xenograft model was utilized to validate in vitro findings. Pretreatment RNA-sequencing of cell lines was performed. MetaVIPER analysis was used to infer protein activity.Results:Exposure to GSK126 and romidepsin demonstrated potent synergy in lymphoma cell lines with EZH2 dysregulation. Combination of romidepsin with other EZH2 inhibitors also demonstrated synergy suggesting a class effect of EZH2 inhibition with romidepsin. Dual inhibition of EZH2 and HDAC led to modulation of acetylation and methylation of H3K27. The synergistic effects of the combination were due to disruption of the PRC2 complex secondary to acetylation of RbAP 46/48. A common basal gene signature was shared among synergistic lymphoma cell lines and was characterized by upregulation in chromatin remodeling genes and transcriptional regulators. This finding was supported by metaVIPER analysis which also revealed that HDAC 1/2 and DNA methyltransferase were associated with EZH2 activation.Conclusions:Inhibition of EZH2 and HDAC is synergistic and leads to the dissociation of PRC2 complex. Our findings support the clinical translation of the combination of EZH2 and HDAC inhibition in EZH2 dysregulated lymphomas.

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Nephrotic syndrome (NS), a frequent chronic kidney disease in children and young adults, is the most common phenotype associated with primary coenzyme Q(10) (CoQ(10)) deficiency and is very responsive to CoQ(10) supplementation, although the pathomechanism is not clear. Here, using a mouse model of CoQ deficiency-associated NS, we show that long-term oral CoQ(10) supplementation prevents kidney failure by rescuing defects of sulfides oxidation and ameliorating oxidative stress, despite only incomplete normalization of kidney CoQ levels and lack of rescue of CoQ-dependent respiratory enzymes activities. Liver and kidney lipidomics, and urine metabolomics analyses, did not show CoQ metabolites. To further demonstrate that sulfides metabolism defects cause oxidative stress in CoQ deficiency, we show that silencing of sulfide quinone oxido-reductase (SQOR) in wild-type HeLa cells leads to similar increases of reactive oxygen species (ROS) observed in HeLa cells depleted of the CoQ biosynthesis regulatory protein COQ8A. While CoQ(10) supplementation of COQ8A depleted cells decreases ROS and increases SQOR protein levels, knock-down of SQOR prevents CoQ(10) antioxidant effects. We conclude that kidney failure in CoQ deficiency-associated NS is caused by oxidative stress mediated by impaired sulfides oxidation and propose that CoQ supplementation does not significantly increase the kidney pool of CoQ bound to the respiratory supercomplexes, but rather enhances the free pool of CoQ, which stabilizes SQOR protein levels rescuing oxidative stress.

The peripheral T-cell lymphomas (PTCL) could be considered the prototypical epigenetic disease. As a disease, they are uniquely sensitive to histone deacetylase (HDAC) and DNA methyltransferase (DNMT) inhibitors, both alone and in combination, are characterized by a host of mutations in epigenetic genes, and can develop spontaneously in genetically engineered murine models predicated on established recurring mutations in (RHOAG17V) and TET2, an epigenetic gene governing DNA methylation. Given the clinical benefit of HDAC inhibitors (HDACi) and hypomethlyation agents alone and in combination in PTCL, we sought to explore a mechanistic basis for these agents in PTCL. Herein, we reveal profound class synergy between HDAC and DNMT inhibitors in PTCL, and that the combination induces degrees of gene expression that are substantially different and more extensive than that observed for the single agents. A prominent signature of the combination relates to the transcriptional induction of cancer testis antigens and genes involved in the immune response. Interestingly, TBX21 and STAT4, master regulators of TH1 differentiation, were among the genes upregulated by the combination, suggesting the induction of a TH1-like phenotype. Moreover, suppression of genes involved in cholesterol metabolism and the matrisome were also identified. We believe that these data provide a strong rationale for clinical studies, and future combinations leveraging an immunoepigenetic platform.

Purpose: Both gain-of-function enhancer of zeste homolog 2 (EZH2) mutations and inactivating histone acetyltransferases mutations, such as CREBBP and EP300, have been implicated in the pathogenesis of germinal center (GC)–derived lymphomas. We hypothesized that direct inhibition of EZH2 and histone deacetyltransferase (HDAC) would be synergistic in GC-derived lymphomas. Experimental Design: Lymphoma cell lines (n = 21) were exposed to GSK126, an EZH2 inhibitor, and romidepsin, a pan-HDAC inhibitor. Synergy was assessed by excess over bliss. Western blot, mass spectrometry, and coimmunoprecipitation were performed. A SU-DHL-10 xenograft model was utilized to validate in vitro findings. Pretreatment RNA-sequencing of cell lines was performed. MetaVIPER analysis was used to infer protein activity. Results: Exposure to GSK126 and romidepsin demonstrated potent synergy in lymphoma cell lines with EZH2 dysregulation. Combination of romidepsin with other EZH2 inhibitors also demonstrated synergy suggesting a class effect of EZH2 inhibition with romidepsin. Dual inhibition of EZH2 and HDAC led to modulation of acetylation and methylation of H3K27. The synergistic effects of the combination were due to disruption of the PRC2 complex secondary to acetylation of RbAP 46/48. A common basal gene signature was shared among synergistic lymphoma cell lines and was characterized by upregulation in chromatin remodeling genes and transcriptional regulators. This finding was supported by metaVIPER analysis which also revealed that HDAC 1/2 and DNA methyltransferase were associated with EZH2 activation. Conclusions: Inhibition of EZH2 and HDAC is synergistic and leads to the dissociation of PRC2 complex. Our findings support the clinical translation of the combination of EZH2 and HDAC inhibition in EZH2 dysregulated lymphomas.

Monoalleleic inactivating mutations in histone acetyltransferase (HAT) enzymes promote lymphomagenesis in germinal center derived B-cell lymphomas, follicular lymphoma (FL) and diffuse large B cell lymphoma (DLBCL), occurring in about 40% of patients. The intact wild-type allele offers an opportunity to leverage the normal enzyme to overcome the pathogenic impact of the mutated allele. We hypothesize that if inactivating mutations in HATs are critical to FL and DLBCL lymphomagenesis, then drugs capable of inducing enhanced function of the wild-type HAT allele product should be cytotoxic in cells harboring HAT mutations. We designed and synthesized a library of new chemical entities with HAT activating properties (N=70). The cytotoxic effects of the compounds (N=29) were evaluated via medium-throughput screening in 4 DLBCL cell lines. IC50 ranged from 3.6 to 43.2 µM. Focusing on 6 analogue compounds, which share the same Nphenylbenzamide scaffold, we evaluated cytotoxicity across an expanded panel of 11 DLBCL cell lines. The median IC50 of 6 analogues tested was lower in the EP300 mutated cell lines (median 9.6 µM, range 5 - 11 µM) compared to the wildtype lines (median, 17 µM, range 15 - 24 µM). YF2 was chosen as the lead compound because it was the most selective of the analogues in inducing cytotoxicity in cell lines harboring EP300 mutations compared to wildtype (IC50 5 µM and 19 µM respectively, p To determine YF2's functional effect on activating p300 in a cell free assay, p300-mediated histone and p53 acetylation was measured by combining recombinant p300, substrate and acetyl-CoA. YF2 increased p300-mediated histone H3 lysine27 acetylation (EC50=38.64 nM) and H3 lysine18 acetylation (EC50=1.656 nM). YF2 also induced acetylation of p53 by 5-fold in a dose dependent manner. In cellular assays, YF2 induces acetylation of histone (H3K27 2-fold and H3K14 1.6-fold) after exposure in the SUDHL-6 cell line (EP300 mutated) as measured by mass spectrometry and confirmed by immunoblot of histone extracts. To assess the pharmacokinetics (PK) and preliminary in vivo efficacy of YF2, SUDHL-6 (EP300-mutated) xenograft bearing mice were treated once daily i.p. for 6 days with YF2 doses of 40mg/kg or 60mg/kg. Serum and tumor samples were collected at sequential time points. The Cmax of YF2 60mg/kg was 2424 ng/mL (5.1 µM) whereas Cmax of 40mg/kg was 2091.96 ng/mL (4.5 µM) which is consistent with the cellular IC50. Both concentrations of YF2, 40mg/kg and 60mg/kg, accumulated in tumor with Cmax 9536.71 and 9858.15 ng/g, respectively. YF2 is rapidly absorbed in the serum (Tmax 0.25 h) and sustained in the tumor (Tmax 4h). Significant effects on tumor size were observed in 13 of 19 mice demonstrating decreased tumor volume following only 6 days of YF2 treatment. Mice treated with YF2 40mg/kg induced H3K27 acetylation in tumor specimens as determined by mass spectrometry.YF2 40mg/kg was well tolerated in SCID/beige mice for 30 days without significant weight loss, while 60mg/kg YF2 led to 20% weight loss during 6-days of treatment. Additionally, YF2 demonstrated cytotoxic effects in 2 primary patient lymphoma samples but were non-cytotoxic to peripheral blood mononuclear cells from healthy donors. Furthermore, we hypothesized that if DLBCL is sensitive to an enhanced acetylation state, then combined targeting of epigenetic machinery with HAT activators and HDAC inhibitors may induce profound epigenetic modification leading to synergistic induction of programmed cell death. The concentration : effect relationship of YF2 and the pan-HDAC inhibitor, romidepsin, was evaluated over time across a panel of lymphoma cell lines (N=7). Synergy was calculated by Excess over Bliss (EOB>10 connotes synergy). Combination of YF2 and romidepsin demonstrated strong synergism in DLBCL lines (EOB = 48). The combination led to enhanced histone acetylation compared to either single agents. The combination is safe in mice and murine xenograft studies of the combination are underway. In summary, YF2 induces HAT-mediated acetylation of histone and p53. It demonstrates selective cytotoxic effects in EP300-mutated DLBCL cell lines, and is both well tolerated and effective in xenograft mouse models of lymphoma suggesting potential clinical application and precision medicine opportunities for patients harboring this mutation. Disclosures O'Connor: Seattle Genetics: Research Funding; ADC Therapeutics: Research Funding; Celgene: Research Funding.

7546Background: EZH2 is the catalytic subunit of PRC2, and induces methylation of H3K27. Activating mutations and overexpression of EZH2 are found in NHL. Inactivating mutations in histone acetyltr...

Peripheral T-cell lymphoma (PTCL) is a heterogeneous group of lymphomas in which only ~25% of patients experience long-term survival with CHOP chemotherapy. Recently several drugs have been approved for this entity including pralatrexate (P), romidepsin (R), and belinostat which have response rates ranging from 26%-29% as single agents. Based on our demonstration of synergy of P+R in preclinical models of TCL, we initiated a study on the safety and efficacy of P+R in a phase I-II study for relapsed or refractory lymphomas (NCT01947140) and sought to evaluate biological mechanisms of synergy. A 3+3 dose-escalation study started at P 10mg/m2 and R 12mg/m2 with escalation to P 25 mg/m2 and R 14 mg/m2. Patients were treated on 1 of 3 dosing schedules (weekly x 3 Q28D; weekly x 2 Q21D and QOW Q28D). The primary objective was to determine MTD and DLT; the secondary objective included describing ORR (CR+PR). Patients were required to have relapsed lymphoma of any subtype, ECOG PS ≤2, and adequate organ and marrow function. There was no upper limit to the number of prior therapies or transplantation. Twenty-six patients were enrolled and were evaluable for toxicity. Median age was 52 yrs (23-73) and 58% were male. The median number of prior therapies was 3 (range 1-16). Histologies included HL (N=3), B-cell (N=10 of which FL=4) and T-cell (N=13). The median number of cycles completed was 4 (range 1-12). There were 3 DLTs in cohort 4 (P 20mg/m2 & R 12mg/m2given weekly x 2 Q21D) consisting of 2 Grade 3 oral mucositis and 1 Grade 4 sepsis. The QOW Q28D schedule had no mucositis at all dose levels. Patients dosed at the MTD (P 25 mg/m2 & R 12mg/m2 QOW) did not experience any toxicities. The grade 3/4 toxicities reported in >5% of patients were: neutropenia (31%), thrombocytopenia (31%), anemia (23%), oral mucositis (15%), hyponatremia (8%), pneumonia (8%) and sepsis (8%). Twenty-two patients were evaluable for response, 1 patient is currently on therapy. The ORR in the total, non-PTCL and PTCL populations was 59%; 33% (no CR) and 77% respectively. Of the PTCL patients 4/13 (31%) achieved a CR, 6/13 (46%) achieved a PR, and 1 patient had stable disease. The mean duration of response (DOR) for all patients on the study (N=13) was 6.1 months (1.1 - 26.5), for the non-PTCL population (N=3) was 4.8 m (1.1-11) and for the PTCL population (N=10) was 6.55 months (range 1.6 - 26.5 +ongoing). The mean progression free survival (PFS) for all patients on study (N=26) was 4.8 m (.3 - 30.2), for the non-PTCL population (N=13) was 2.8 m (0.3-14.5), and for the PTCL population was 6.13 months (range 1.5 - 30.2 +ongoing). Pharmacokinetic studies were performed for P and R and data for the first 15 patients is presently available for reporting. PK analyses were performed using WinNonLin® to determine Cmax and AUC. Preliminary Cmax results for P 10 mg/m2 and P 15 mg/m2 are 1810+/-1063 ng/mL and 2748+/-995 ng/mL, respectively. Preliminary Cmax results for R 12 mg/m2 and R 14 mg/m2 are 420+/-198 ng/mL and 552+/- 346 ng/mL, respectively. After infusion with P 10 mg/m2 or 15 mg/m2 PK analysis indicate AUC0-24.08h of 3616+/-1543 h*ng/mL and 4104+/-2124 h*ng/mL, respectively. AUC0-28h after treatment with R 12 mg/m2or 14 mg/m2 was 1503+/-1286 h*ng/ml and 2535+/-2560 h*ng/mL. These values are consistent with that observed for both of these drugs in previous studies. Results from the phase I study conclude that the combination of P + R given on the QOW schedule is safe and very well tolerated. These data support the lineage specific activity of the P+R combination, which is currently being expanded to a multicenter Phase II for PTCL. Figure Figure. Disclosures Amengual: Bristol-Myers Squibb: Research Funding; Acetylon Pharmaceuticals, Inc: Research Funding. Sawas:Seattle Genetics: Honoraria; Gilead Sciences: Speakers Bureau. O'Connor:Spectrum: Research Funding; Seattle Genetics: Research Funding; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Research Funding; Mundipharma: Membership on an entity's Board of Directors or advisory committees; Spectrum: Research Funding; TG Therapeutics: Research Funding; TG Therapeutics: Research Funding; Bristol Myers Squibb: Research Funding; Bristol Myers Squibb: Research Funding; Celgene: Research Funding; Celgene: Research Funding.

BACKGROUND This study determined the effects of S-allylmercaptocysteine (SAMC), a phytoconstituent from garlic, on the expression of androgen-responsive biomarkers, prostate specific antigen (PSA), and prostate specific membrane antigen (PSMA), in human prostatic carcinoma cells (LNCaP). METHODS Secretion of PSA was determined as well as the activity of PSMA measured as a function of its ability to hydrolyze poly-γ-glutamated folate and N-acetylaspartylglutamate (NAAG). Folate hydrolase capacity was also determined in SAMC-treated cells grown in charcoal stripped fetal calf serum (CS-FCS). In addition, testosterone disappearance was measured from culture media of SAMC-treated LNCaP and PC-3 cells as well as from cell free lysates. RESULTS PSA secretions were significantly decreased compared to control values at 1 day (8.4 ± 2.6 vs. 18.9 ± 1.7, P < 0.01), 4 days (18.9 ± 5.3 vs. 73.8 ± 4.4, P < 0.001), and 6 days (35.6 ± 2.1 vs. 96.5 ± 17.9 ng/105 cells, P < 0.01; mean ± SD). By contrast, PSMA activity measured as either folate hydrolase or NAAG dipeptidase (NAALADase) activity increased in cells treated with SAMC. PSMA-folate hydrolase activity in SAMC-treated cells grown in CS-FCS increased beyond that observed in cells grown in CS-FCS alone. Pre-exposure of LNCaP cells to SAMC resulted in enhanced rate of testosterone disappearance from culture media at 6 hr (P < 0.01) and at 48 hr (P < 0.001) compared to media from cells not previously exposed to SAMC. Results similar to these were also observed in androgen-independent PC-3 cells treated with SAMC. In lysates of SAMC-treated LNCaP cells, the rate of testosterone catabolism was twice that from phosphate buffered saline (PBS)-treated cells. SAMC-treated LNCaP cells grown in media supplemented with testosterone temporarily exhibited enhanced growth over a 2 day period but cell numbers declined later to levels similar to those of SAMC treatment. CONCLUSIONS These results show that SAMC exhibits differential effects on recognized biomarkers for LNCaP cells similar to those produced by androgen deprivation and strongly suggests that this effect may be mediated, in part, by diminishing the trophic effects of testosterone, likely by converting it to metabolites less reactive toward androgen receptors. Prostate 45:304–314, 2000. © 2000 Wiley-Liss, Inc.

This study investigated whether naturally occurring garlic derivatives and synthetic S-cysteinyl compounds that resemble garlic constituents have antiproliferative effects on human prostate carcinoma (LNCaP) cells. Studies also examined whether S-allylmercaptocysteine and S-allylcysteine affect two important molecular targets, namely reduced glutathione and polyamines. Results showed that S-allylmercaptocysteine (50 mg/L) diminished LNCaP cell growth whereas the antiproliferative effect of S-allylcysteine was not as pronounced. Studies using synthetic S-cysteinyl analogues revealed that growth inhibition was most effective with compounds containing a disulfide or an active diallyl moiety. Marginal to no inhibitory effect was observed with monosulfinic analogues. Both S-allylmercaptocysteine and S-allylcysteine caused an increase in LNCaP cell reduced glutathione concentrations. Putrescine and spermine concentrations decreased and spermidine increased 3 d after S-allylmercaptocysteine treatment. At 5 d after S-allylmercaptocysteine treatment, polyamine concentrations were similar to those of saline-treated controls. Diminished cell growth and altered polyamine concentrations suggest that S-allylmercaptocysteine may impede the polyamine synthesizing enzyme, ornithine decarboxylase, either by enhancing the formation of reduced glutathione, a known inhibitor of ornithine decarboxylase, or by reacting directly with ornithine decarboxylase at its nucleophilic thiol moiety. Because S-allylcysteine also increases reduced glutathione formation but does not significantly inhibit growth, the latter mechanism may be more likely for this compound. These data provide further evidence that nonessential nutrients derived from garlic may modulate tumor growth. Further research is required on effects of garlic derivatives in vivo before information from the present studies can be used to assist in the development of effective nutritional strategies for preventing progression of prostate cancer.

Factors controlling glutathione metabolism may govern sensitivity to chemotherapeutic agents such as cisplatin. Using a battery of cell lines derived from previously untreated head and neck squamous cell carcinomas, we examined cisplatin resistance relative to (a) glutathione-S-transferase (GST)-pi gene amplification and expression, (b) basal and inducible GST-total and GST-pi enzymatic activity, and (c) cellular levels of reduced glutathione (GSH). Using Southern blot analysis and northern blot hybridization, no relationship between GST-pi gene amplification, mRNA expression and drug resistance could be identified. Despite the capacity of cisplatin to induce GST enzyme activity, the response was variable and unrelated to cisplatin responsiveness. However, an inverse relationship between GSH levels and cisplatin sensitivity was identified. To further clarify these effects, cells were treated with S-allyl cysteine (SAC), a thioallyl derivative isolated from garlic (Allium sativum), which altered cellular GSH in a biphasic manner. Pretreatment with SAC to lower cellular GSH levels followed by exposure to cisplatin significantly enhanced the cytotoxic effects of cisplatin, while SAC alone had no effect on cell growth.