Abstract 5321: BRG399: A novel potent small molecule modulator of UBE2K for the treatment of various cancers

The ubiquitin-proteasome system (UPS) plays an important role in cellular processes for protein quality control and homeostasis and indeed, dysregulation within the pathway has implications in numerous diseases, especially cancer. Here, we introduce BRG399, a novel modulator of UBE2K - a unique E2 conjugating enzyme of the UPS, that we previously identified as a potential therapeutic target using BERG’s Interrogative Biology® platform. The anticancer potential of UBE2K modulation was validated by gene manipulation using siRNA mediated knockdown of UBE2K in several cancer cell models. Knockdown of UBE2K resulted in a 50% decrease in cell number in MIA PaCa2 cells and a 30% decrease in cell number in SKHEP1 and HepG2 cells at 96h post transfection. This effect was the result of a robust G2/M cell cycle arrest associated with increased CyclinB1 expression. In addition, a modest increase in apoptosis/necrosis (6-8%) was observed in cells with UBE2K knockdown. Using Fragment-Based Ligand Discovery and structure-based drug design, BRG399 was developed as a new chemical entity (NCE) which binds to UBE2K, resulting in modulation of several established canonical functions and an anti-cancer phenotype. In a panel of 102 cancer cell lines, BRG399 exhibited an anti-cancer activity in all cell lines tested as evident by extrapolation of IC50 and %Max Effect values from the dose response curves. In all but one cell line, double to triple digit nanomolar potency was observed ranging from 17nM to 318 nM and viability of 76 cell lines was reduced by more than 70%. The anti-cancer potency of BRG399 was also established in a multi-tumor type panel of patient-derived organoids (PDO) of which 68% were highly or partially responsive to BRG399 as indicated by 37-73% decrease in PDO viability. Mechanistic studies demonstrated that BRG399’s anti-cancer effect was a result of a robust G2/M cell cycle arrest and apoptosis mediated cell death. Molecular events associated with G2/M arrest included stabilization of CyclinB1 and sustained activation of cyclin-dependent kinase CDK1, while those associated with apoptosis involved decreased expression of anti-apoptotic proteins Bcl-XL and Mcl-1 and increased expression of cleaved PARP (cPARP) and Capase 3. Together, these results support a novel role for UBE2K in the regulation of the cell cycle in cancer cells and demonstrate that its modulation by BRG399 influences phenotypic end-points consistent with an anti-cancer effect.

Citation Format: Maria-Dorothea Nastke, Marisa Permatteo, Pragalath Sundararajan, Shefali Sharma, Jacob Matson, Kaleigh Gray, Arcan Guven, Shiva Kazerounian, Anne Diers, Rangaprasad Sarangarajan, Niven R. Narain, Vivek K. Vishnudas, Stephane Gesta. BRG399: A novel potent small molecule modulator of UBE2K for the treatment of various cancers [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5321.

Abstract 5320: BRG399, a small molecule modulator of UBE2K demonstrated dose-dependent anti-cancer efficacy in an in vivo model for gastric cancer

Gastric cancer is difficult to treat and exhibits poor survival with current therapies (five-year survival for all stages is 32% and 5% for metastatic gastric cancer) demonstrating a clear unmet clinical need. UBE2K was identified as a drug target from the BERG Interrogative Biology® Platform, from an Artificial Intelligence derived in vitro pan-cancer Bayesian network. UBE2K (also known as Huntington Interacting Protein 2 and E2-25K) is one of the ~40 E2 enzymes from the Ubiquitin Proteasome System and belongs to the Class II of E2 enzymes that preferentially catalyze the synthesis of Lys48-linked changes on monoubiquitinated substrates. Recently, high expression of UBE2K in tumors of gastric cancer patients has been shown to associate with poor prognosis. BERG has developed BRG399 as a candidate molecule to modulate UBE2K activity for use in oncology. Here, we evaluated the anti-cancer effect of BRG399 using Hs 746T, a human xenograft in vivo model for gastric cancer. In vitro evaluation of BRG399 potency revealed an IC50 of 44.3nM in Hs 746T cells. For determination of BRG399 potency in vivo, nude mice were inoculated subcutaneously with Hs 746T cell line and tumors were allowed to reach 120mm3. Animals were then randomized into four groups to receive oral administration of vehicle, 75, 100, or 150mg/kg of BRG399 twice per day for 15 days. The result revealed that BRG399 significantly decreased the growth of Hs 746T tumors in a dose-dependent manner. Statistical analysis using a mixed effect linear model of the tumor volumes on the last day of study demonstrated a tumor growth inhibition of 60.3, 71.2 and 85.3% at the three doses, respectively, without any significant effect on body weight. These results are well correlated with the dose-dependent increase of BRG399 in both plasma and tumor tissues. Anti-tumor effect of BRG399 appears to be the result of G2/M arrest, as indicated by a dose-dependent elevation of two cell cycle-dependent biomarkers, CNNB1 and pHH3, in tumor tissue. This is consistent with the role of UBE2K in regulating several components of cell cycle for dictating the precise timing of cell division. Mixed effect multivariable regression modeling was employed to identify the relationship between these two biomarkers and response. This analysis indicated that the level of plasma concentration of BRG399, together with the tumor levels of CNNB1 and pHH3, are significantly and negatively associated with tumor volume, allowing an inference that these biomarkers are indicative and/or involved in the tumor response of BRG399. In summary, these results signify the anti-cancer efficacy of BRG399 and support its potential as a drug candidate for treatment of gastric cancer.

Citation Format: Shiva Kazerounian, Mollie O'Hara, Arcan Guven, Kashni Grover, Nicole Pellegrino, Kayleigh Gray, Can Bruce, Gregory M. Miller, Maria-Dorothea Nastke, Michael A. Kiebish, Eric M. Grund, Rangaprasad Sarangarajan, Niven R. Narain, Stephane Gesta, Vivek K. Vishnudas. BRG399, a small molecule modulator of UBE2K demonstrated dose-dependent anti-cancer efficacy in an in vivo model for gastric cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5320.

Abstract 2328: Interrogating the anti-cancer effects of co-enzyme Q10 (CoQ10) identifies metabolic and mitochondrial apoptotic responses as primary mechanisms in squamous cell carcinoma model

Targeting mitochondrial function as a therapeutic modality in cancer has been extensively investigated. BPM 31510 is a proprietary drug-lipid nanoconjugate formulation enabling delivery of supra-physiological concentrations of oxidized CoQ10 specifically into mitochondria. In this study, the anti-cancer properties of CoQ10 in squamous cell carcinoma (SCC) and its mechanism of action were investigated in in vivo xenograft and in vitro model systems. Nude mice were inoculated with a squamous carcinoma cell line isolated from tongue, SCC-25, and treated with a topical formulation containing 1.5% or 5% CoQ10. Treatment was associated with a dose-dependent delay in the detection of palatable tumors (14 ± 3 days vehicle control, 27 ± 7 days 1.5% cream, 39 ± 9 days 5% cream), (p<0.05). Histology and immunostaining analysis demonstrated a decrease in expression of VEGF in the treatment groups (p<0.05). The anti-cancer mechanism of action of CoQ10 was further investigated by interrogating the influence of CoQ10 exposure on molecular profiles using SCC-25 cells in vitro. Cell based assays, mRNA-based RT-PCR assays, and protein-based antibody chip microarrays confirmed an apoptotic response as a major anti-cancer effect in SCC-25 cells in response to CoQ10 exposure. The change in anti- and pro-apoptotic markers (Bcl-2 and caspase families) was independently confirmed by western blotting. In addition, global proteomic analysis revealed alterations in key metabolic proteins in the Pentose Phosphate Pathway (PPP). For example, expression of Transaldolase 1, an enzyme involved in the cellular protection against oxidative stress, resistance/susceptibility to apoptosis, and SCC tumor development and progression, was reduced 1.5 fold at both 6 and 24 hour time point in response to CoQ10 treatment. Together, the data suggests that CoQ10 influences cancer metabolism and redox pathway in activating apoptosis in SCC cancer model.

Citation Format: Niven R. Narain, Shiva Kazerounian, Shivani Khatu, Anne R. Diers, John McCook, Stephane Gesta, Robert S. Kirsner, Brian Berman, Rangaprasad Sarangarajan. Interrogating the anti-cancer effects of co-enzyme Q10 (CoQ10) identifies metabolic and mitochondrial apoptotic responses as primary mechanisms in squamous cell carcinoma model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2328.

Elevated levels of mitochondrial CoQ10 induce ROS-mediated apoptosis in pancreatic cancer

Reactive oxygen species (ROS) are implicated in triggering cell signalling events and pathways to promote and maintain tumorigenicity. Chemotherapy and radiation can induce ROS to elicit cell death allows for targeting ROS pathways for effective anti-cancer therapeutics. Coenzyme Q10 is a critical cofactor in the electron transport chain with complex biological functions that extend beyond mitochondrial respiration. This study demonstrates that delivery of oxidized Coenzyme Q10 (ubidecarenone) to increase mitochondrial Q-pool is associated with an increase in ROS generation, effectuating anti-cancer effects in a pancreatic cancer model. Consequent activation of cell death was observed in vitro in pancreatic cancer cells, and both human patient-derived organoids and tumour xenografts. The study is a first to demonstrate the effectiveness of oxidized ubidecarenone in targeting mitochondrial function resulting in an anti-cancer effect. Furthermore, these findings support the clinical development of proprietary formulation, BPM31510, for treatment of cancers with high ROS burden with potential sensitivity to ubidecarenone.

High levels of ubidecarenone (oxidized CoQ10) delivered using a drug-lipid conjugate nanodispersion (BPM31510) differentially affect redox status and growth in malignant glioma versus non-tumor cells

Metabolic reprogramming in cancer cells, vs. non-cancer cells, elevates levels of reactive oxygen species (ROS) leading to higher oxidative stress. The elevated ROS levels suggest a vulnerability to excess prooxidant loads leading to selective cell death, a therapeutically exploitable difference. Co-enzyme Q₁₀ (CoQ₁₀) an endogenous mitochondrial resident molecule, plays an important role in mitochondrial redox homeostasis, membrane integrity, and energy production. BPM31510 is a lipid-drug conjugate nanodispersion specifically formulated for delivery of supraphysiological concentrations of ubidecarenone (oxidized CoQ₁₀) to the cell and mitochondria, in both in vitro and in vivo model systems. In this study, we sought to investigate the therapeutic potential of ubidecarenone in the highly treatment-refractory glioblastoma. Rodent (C6) and human (U251) glioma cell lines, and non-tumor human astrocytes (HA) and rodent NIH3T3 fibroblast cell lines were utilized for experiments. Tumor cell lines exhibited a marked increase in sensitivity to ubidecarenone vs. non-tumor cell lines. Further, elevated mitochondrial superoxide production was noted in tumor cells vs. non-tumor cells hours before any changes in proliferation or the cell cycle could be detected. In vitro co-culture experiments show ubidecarenone differentially affecting tumor cells vs. non-tumor cells, resulting in an equilibrated culture. In vivo activity in a highly aggressive orthotopic C6 glioma model demonstrated a greater than 25% long-term survival rate. Based on these findings we conclude that high levels of ubidecarenone delivered using BPM31510 provide an effective therapeutic modality targeting cancer-specific modulation of redox mechanisms for anti-cancer effects.

Abstract 2943: Interrogative Biology® platform identifies a novel target in the ubiquitin pathway and its utility in cancer is supported by small molecule modulators

Identification of novel therapeutic targets for the development of drugs with a large spectrum of applications in oncology is extremely difficult due, in part, to the complex and heterogenous etiology of the disease. To address this, we interrogated in vitro cancer models representative of multiple tumor types (HepG2, MIA PaCa2, SKMEL28, SCC-25, SkBr-3 MCF7, PC-3, and LnCAP) and compared them to non-tumorigenic and primary cells. Proteomic profiling of these models under various cancer relevant perturbations and analysis through a Bayesian Artificial Intelligence algorithm (Interrogative Biology® platform) allowed the generation of causal inference networks which identified BPM42522 as potential therapeutic target. The anticancer potential of BPM42522, an enzyme in the ubiquitin proteasomal system, was then validated through molecular and pharmacological modulation. siRNA mediated knockdown of BPM42522 resulted in a 50% decrease in cell number in MIA PaCa2 cells and a 30% decrease in cell number in SKHEP1 and HepG2 cells at 96h post transfection. This effect was the result of a robust G2/M cell cycle arrest associated with increased CyclinB1 expression. In addition, a modest increased in apoptosis/necrosis (6-8%) was observed in cells with BPM42522 knockdown. Using Fragment-Based Ligand Discovery, we developed a series of compounds modulating BPM42522 activity and exhibiting anti-cancer properties. A panel of cells lines (Oncolines™) was used to evaluate the potency of our optimized lead compounds. Of 102 cell lines, treatment with optimized lead molecules for 72h reduced the viability of 76 cells lines by more than 70% with an IC50 ranging from 17nM to 318nM. Additional studies on a selected panel of cancer cell lines, upon treatment with modulators, demonstrated that this effect was the result of a G2/M arrest occurring as early as 5h and significantly different by 24h. The accumulation of cells in G2/M was confirmed by increased expression of CyclinB1 and phospho-histone H3 in a dose dependent manner. Furthermore, this increase in G2/M arrest was followed by an increase in apoptosis which could be observed within 24h and progressed until 72h. Identification of BPM42522 as a target for cancer and development of small molecule modulators demonstrates the utility of BERG's Interrogative Biology® platform in elucidating fundamental biology to identify novel therapeutic targets, based on causality, with broad anti-cancer properties.

Citation Format: Stephane Gesta, Shefali Sharma, Pragalath Sundararajan, Mingshu Huang, Kayleigh Gray, Maria Nastke, Arcan Guven, Anne Diers, Shiva Kazerounian, Suwagmani Hazarika, Eric M. Grund, Vivek K. Vishnudas, Niven R. Narain, Rangaprasad Sarangarajan. Interrogative Biology® platform identifies a novel target in the ubiquitin pathway and its utility in cancer is supported by small molecule modulators [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2943.

Abstract 2968: BPM31510, a Coenzyme Q10 (CoQ10) containing lipid nanodispersion, enhances radiation effects to prolong survival in a rodent glioblastoma model

BPM31510 is a Coenzyme Q10 (CoQ10)-containing lipid nanodispersion in clinical development for the treatment of glioblastoma. Prior results demonstrate that high doses of CoQ10 delivered via BPM31510 differentially increases oxidative stress in glioblastoma relative to non-tumor cells in vitro and extends long-term survival (LTS) in an in vivo glioblastoma model. Since a primary consequences of tumor irradiation is induction of oxidative stress, we hypothesized that BPM31510 treatment would result in an enhanced radiation response and influence survival outcomes.1 x 106 luciferase labeled C6 cells were implanted into the right striatum of Sprague Dawley rats. 4 days post-implantation, rats were randomized into one of four groups: (i) Saline injection ip bid; (ii) BPM31510 50 mg/kg ip bid to continue up to 35 days; (iii) 12 Gy radiotherapy (RT) to be administered on Day 8 post-implant with saline injection; and (iv) BPM31510 + RT. Tumor-bearing rats were monitored until death or Day 50. Log rank survival analysis indicated a marked enhancement of median survival with the addition of BPM31510 to RT. While neither RT nor BPM31510 enhanced median survival relative to saline, the combination was markedly more effective (median survival of 17, 19, 24 and >50 days for saline, BPM31510, RT and combination, respectively, p < 0.001). This was also reflected in increase in frequency of LTS, which was over 70% (11 of 14 rats) in the combination group (p < 0.01 compared to control). BPM31510 significantly enhanced the therapeutic efficacy of radiation in this model of glioblastoma. Effects on median survival and an enhancement of LTS with combination treatment were observed. While the mechanistic underpinnings are under investigation, the low toxicity profile of BPM31510 and its potential protective effects on normal cells may offer a unique strategy with which to enhance radiation.

Citation Format: Jiaxin Sun, Milton Merchant, Anne R. Diers, Shiva Kazerounian, Stephane Gesta, Niven R. Narain, Rangaprasad Sarangarajan, Seema Nagpal, Lawrence Recht. BPM31510, a Coenzyme Q10 (CoQ10) containing lipid nanodispersion, enhances radiation effects to prolong survival in a rodent glioblastoma model [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2968.

Abstract 3608: BPM31510 exploits differential redox vulnerabilities between normal and glioblastoma cells to mediate its anti-cancer effect

Glioblastoma is an aggressive cancer, the proliferative capacity of which is correlated with glycolytic metabolism. BPM31510 is a novel formulation for delivery of supraphysiological levels of ubidecarenone to the mitochondria, enabling cancer specific metabolic switches. It is being studied in Phase I clinical trials versus a number of tumors, including glioma. Here, the effects of ubidecarenone on viability and redox homeostasis of glioma and non-tumorigenic cells was assessed using in vitro monoculture and coculture systems and an in vivo preclinical model. BPM31510 administration (50 mg/kg bid i.p., beginning 4-8 days post-inoculation) resulted in over a 20% long term survival rate in C6 tumor-bearing rats. We next compared BPM31510 effects in vitro between glioma lines (rat C6, human U251) and murine NIH3T3 fibroblasts, as a stromal control. In monocultures, decreased growth was observed in glioma lines and NIH3T3 with increasing BPM31510 doses; however, glioma lines were 2-fold more sensitive to BPM31510 compared to NIH3T3 cells (IC50 glioma lines: 230 µM vs IC50 NIH3T3: >460 µM). To investigate the differential sensitivity to BPM31510, a coculture system was developed by coincubating 2 x 105 C6-GFP labeled cells and NIH3T3 cells. After 6 days of coculture, the percentage of C6 relative to NIH3T3 cells was lowest at doses of BPM31510 between 115 µM and 230 µM, evidence of greater sensitivity to BPM31510-induced cytotoxicity in the C6 glioma cells than the non-tumorigenic component. At higher doses, differential effects on cell viability were less apparent. The level of superoxide, a central reactive oxygen species important in redox homeostasis, was also assessed using Mitosox in cocultures. At a BPM31510 dose which resulted in maximal differential viability between C6 and NIH3T3 cells (230 μM), the maximal differential superoxide level was likewise greatest. The basal differential in Mitosox signal was 9-fold between C6 and NIH3T3 cells, and it increased to over 50-fold upon treatment with BPM31510 (230 μM), implying that BPM31510 exploits differential redox vulnerabilities between C6 and NIH3T3 to mediate its anti-cancer activity. At high doses of BPM31510, differential effects on superoxide levels were less apparent. In summary, BPM31510 has marked anti-cancer activity in rats implanted with C6 glioma, and its differential effects on the viability of normal and transformed cells are associated with maximal differences in BPM31510-induced superoxide production. Together, these data suggest that differential redox vulnerabilities between tumorigenic and non-tumorigenic cells may underpin the anti-cancer activity of BPM31510, and identification of in vivo correlates of redox indices may represent an avenue to improved measurement of anti-cancer efficacy as well as define patient populations responsive to BPM31510.

Citation Format: Jiaxin Sun, Seema Nagpal, Chirag Patel, Milton Merchant, Tiachang Jang, Anne R. Diers, Shiva Kazerounian, Stephane Gesta, Niven R. Narain, Rangaprasad Sarangarajan, Lawrence Recht. BPM31510 exploits differential redox vulnerabilities between normal and glioblastoma cells to mediate its anti-cancer effect [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3608.

Abstract 4915: Preclinical pharmacology and toxicology of intravenous BPM31510, a coenzyme Q10-containing lipid nanodispersion

Coenzyme Q10 (CoQ10) plays an important role in cellular metabolism with redox capabilities beyond the mitochondria. Although, the role of CoQ10 in providing benefit in diseases such as cardiovascular, neurodegeneration, and cancer is well established, it has been limited by the absence of delivery methods to achieve physiologically relevant bio-availability. BPM31510 is a CoQ10 (ubidecarenone) containing lipid nanodispersion that delivers supraphysiological concentrations of CoQ10 to tissues, cells and mitochondria. BPM31510 is currently in clinical trials for the treatment of solid tumors including pancreatic cancer and glioblastoma multiforme. This study describes the preclinical pharmacokinetic (PK) and toxicokinetic assessment of BPM31510 (62.5, 125, and 250 mg/kg) after acute (single) intravenous (IV) administration and chronic (3 times a week for 4 weeks), and after a two week recovery from the last exposure in rats. Here, it was demonstrated that the formulation enables an effective delivery of CoQ10 with a robust increase in plasma level and dose-dependent accumulation in several tissues. PK analysis of mean plasma concentration of CoQ10 after a single and repeat dose administration revealed a dose proportion effect on peak (Cmax) and total exposure (AUC0-t). Tissue analysis of CoQ10 levels demonstrates a dose-dependent increase in liver, lung and pancreas 72 hours post-last dose. A dose dependent elimination was observed in both male and females. No difference in pharmacokinetic of CoQ10 using this formulation was observed between males and females. Notably, chronic exposure to BPM31510 does not lead to toxicities as assessed by hematology and coagulation, clinical chemistry, histopathology and gross necropsy. These results indicate that the effective delivery and bioavailability of supraphysiological levels of CoQ10 after IV administration of BPM31510 is well tolerated.

Citation Format: David Linsenmayer, Shiva Kazerounian, Khampaseuth Thapa, Carrie Spencer, Aishwarya Sarma, John McCook, Stephane Gesta, Vivek Vishnudas, Niven R. Narain, Rangaprasad Sarangarajan. Preclinical pharmacology and toxicology of intravenous BPM31510, a coenzyme Q10-containing lipid nanodispersion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4915.

Abstract 4724: Immuno-modulatory activity of BPM31510 supports T cell viability, proliferation, and function while reversing early signs of exhaustion

Regulation of mitochondrial metabolism is crucial to alter immune cell differentiation and function; therefore, therapeutic agents which regulate mitochondrial metabolism may have efficacy in immune-mediated tumor elimination. BPM31510 is a clinical stage, nanodispersion of ubidecarenone (coenzyme Q10), an electron transfer molecule in the mitochondrial electron transport chain required for oxidative phosphorylation. Here, we used BPM31510 to assess the role of CoQ10 in the regulation of T cell function. Healthy donor peripheral blood mononuclear cells (PBMCs) activated ex vivo with αCD3/CD28 beads were used as model system to test the effects of BPM31510 on viability and functionality of T cell subpopulations. In contrast to its ability to initiate regulated cell death in cancer cells, treatment of PBMCs with increasing concentrations of BPM31510 lead to an increased frequency of viable CD3+ cells. Further phenotypic analysis revealed that cytotoxic T cells (CD8+/CD3+) and T helper cells (CD4+/CD3+), as well as NKT cells (CD56+/CD3+), contributed to the observed increase in T cell frequency. Proliferation measurements by EdU-incorporation indicated enhanced cytotoxic T cell proliferation in BPM31510 treated PBMCs, and likewise, BPM31510 increased degranulation of activated cytotoxic T cells, as indicated by measurement of plasma membrane-exposed lysosomal-associated membrane protein 1 (CD107a). Consistent with the ex vivo observations, in vivo studies using the syngeneic MC38 murine tumor model demonstrated that BPM31510 administration resulted in a dose-dependent enhancement of the number of CD3+ cells in the tumor microenvironment with cytotoxic T cells (CD8+/CD3+) representing the largest population. Together, these data define a supportive effect of BPM31510 on T cell frequency, viability, and functionality. In addition, in ex vivo activated PBMCs, BPM31510 decreased the percentage of PD1+ T cells while simultaneously increasing the percentage of PD1- T cells in the population. Moreover, in the PD1+ T cell population, PD1 expression on the cell surface was increased while PD1- T cells experienced no change in cell surface expression of PD1. These data suggest BPM31510 treatment promotes highly functional cytotoxic T cells while cells with early signs of exhaustion are induced to follow the path of exhaustion and elimination. Collectively, these results define an immune-modulatory activity for BPM31510, particularly in the T cell compartment, in part, through regulation of T cell exhaustion; this may have important implications for the use of BPM31510 in ‘immunologically cold' tumor types or in combination with immune checkpoint blockade strategies.

Citation Format: Maria Nastke, Shiva Kazerounian, Nidhi Gaur, Shyamali Jayashankar, David Linsenmayer, Carrie Spencer, Arun Nambiar, Aishwarya Sarma, Anne R. Diers, Stephane Gesta, Vivek Vishnudas, Vikas P. Sukhatme, Niven R. Narain, Rangaprasad Sarangarajan. Immuno-modulatory activity of BPM31510 supports T cell viability, proliferation, and function while reversing early signs of exhaustion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4724.

Abstract 5576: BPM 31510, a clinical stage candidate demonstrates potent anti-tumor effect in an immune-competent syngeneic pancreatic cancer model

BPM 31510, a clinical stage nanodispersion of ubidecarenone, demonstrates anti-tumor effects by eliciting an anti-Warburg metabolic switch in cancer. Previous studies in an immune compromised PaCa2 xenograft model has unequivocally demonstrated significant efficacy of BPM 31510 on tumor volume and survival. The fundamental property of BPM 31510 to influence mitochondrial bioenergetics and the recognized interplay between T cell metabolism and maturation prompted investigation into the effects of BPM 31510 on T lymphocyte functions in eliciting anti-cancer effects. In this study BPM 31510 selectively influenced activation and maturation of T cells in murine peripheral blood mononuclear cells (PBMCs). Moreover, in addition to determining changes in the CD3+ population, changes in surface expression of PD-1 and CTLA4 along with the IFN-γ secretion were examined. Murine cancer cell lines exposed to BPM 31510 were associated with variable sensitivity with highly metabolic tumor types being most sensitive. Next, the anti-cancer activity of BPM 31510 in an in vivo immunocompetent syngeneic Pan02 rodent model was investigated. Murine Pan02 pancreatic cancer cells were implanted subcutaneously into C57BL/6 mice. Tumors with mean volume of 80 mm3 were treated twice a day with vehicle control or BPM 31510 at 25, 50, 100 mg/kg, administered intraperitoneal. Tumor volumes were measured every 4 days. At day 21 post treatment, tumors were harvested and analyzed for the level of infiltrating immune cells by immunofluorescent staining with CD8+ for T cells and F4/80 for tumor macrophages. These results demonstrate a dose-dependent reduction in tumor volume following 21 days of BPM 31510 treatment. In summary, BPM 31510 exerts potent anti-tumor effects through its dual function of modulating tumor cell metabolism and potentially influencing immune check-point to improve overall survival outcomes.

Citation Format: Shiva Kazerounian, Aishwarya Sarma, Nidhi Gaur, Maria D. Nastke, Tulin Dadali, Anne R. Diers, Stephane Gesta, Vivek K. Vishnudas, Rangaprasad Sarangarajan, Niven R. Narain. BPM 31510, a clinical stage candidate demonstrates potent anti-tumor effect in an immune-competent syngeneic pancreatic cancer model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5576. doi:10.1158/1538-7445.AM2017-5576

RhoB controls coordination of adult angiogenesis and lymphangiogenesis following injury by regulating VEZF1-mediated transcription

Mechanisms governing the distinct temporal dynamics that characterize post-natal angiogenesis and lymphangiogenesis elicited by cutaneous wounds and inflammation remain unclear. RhoB, a stress-induced small GTPase, modulates cellular responses to growth factors, genotoxic stress and neoplastic transformation. Here we show, using RhoB null mice, that loss of RhoB decreases pathological angiogenesis in the ischaemic retina and reduces angiogenesis in response to cutaneous wounding, but enhances lymphangiogenesis following both dermal wounding and inflammatory challenge. We link these unique and opposing roles of RhoB in blood versus lymphatic vasculatures to the RhoB-mediated differential regulation of sprouting and proliferation in primary human blood versus lymphatic endothelial cells. We demonstrate that nuclear RhoB-GTP controls expression of distinct gene sets in each endothelial lineage by regulating VEZF1-mediated transcription. Finally, we identify a small-molecule inhibitor of VEZF1-DNA interaction that recapitulates RhoB loss in ischaemic retinopathy. Our findings establish the first intra-endothelial molecular pathway governing the phased response of angiogenesis and lymphangiogenesis following injury.

RhoB differentially controls Akt function in tumor cells and stromal endothelial cells during breast tumorigenesis

Tumors are composed of cancer cells but also a larger number of diverse stromal cells in the tumor microenvironment. Stromal cells provide essential supports to tumor pathophysiology but the distinct characteristics of their signaling networks are not usually considered in developing drugs to target tumors. This oversight potentially confounds proof-of-concept studies and increases drug development risks. Here, we show in established murine and human models of breast cancer how differential regulation of Akt by the small GTPase RhoB in cancer cells or stromal endothelial cells determines their dormancy versus outgrowth when angiogenesis becomes critical. In cancer cells in vitro or in vivo, RhoB functions as a tumor suppressor that restricts EGF receptor (EGFR) cell surface occupancy as well as Akt signaling. However, after activation of the angiogenic switch, RhoB functions as a tumor promoter by sustaining endothelial Akt signaling, growth, and survival of stromal endothelial cells that mediate tumor neoangiogenesis. Altogether, the positive impact of RhoB on angiogenesis and progression supercedes its negative impact in cancer cells themselves. Our findings elucidate the dominant positive role of RhoB in cancer. More generally, they illustrate how differential gene function effects on signaling pathways in the tumor stromal component can complicate the challenge of developing therapeutics to target cancer pathophysiology.

RhoB loss prevents streptozotocin-induced diabetes and ameliorates diabetic complications in mice

RhoB is an early-response gene whose expression is elevated by multiple cellular stresses; this gene plays an important role in cancer, macrophage motility, and apoptosis. These factors are essential for the onset of type 1 diabetes mellitus and related complications. This study explores the role of RhoB in β-cell depletion and hyperglycemia-associated complications and tests whether the pleiotropic effect of statins on glycemic control is RhoB dependent. We induced β-cell depletion in RhoB(+/+), RhoB(+/-), and RhoB(-/-) mice with streptozotocin (STZ). Diabetic status was assessed by glucose tolerance and pancreatic islet loss. RhoB(-/-) mice showed a significant reduction in the severity of STZ-induced diabetes; only 13% of the STZ-treated RhoB-null animals became hyperglycemic, as opposed to 61% of the wild-type controls. Diabetes-related complications, such as wound healing rate and onset of nephropathy, were also assessed. Hyperglycemic RhoB(-/-) mice had fewer signs of nephropathy and showed faster wound healing than RhoB(+/+) animals. After assessing the diabetic status of mice treated simultaneously with STZ and simvastatin, we conclude that the effect of statins in improving glycemic control is RhoB independent. We propose that RhoB is a modifier of diabetes, important for the induction of β-cell loss. Suppression of RhoB expression may have potential application in the treatment of diabetes and associated complications.

Thrombospondins in cancer

The thrombospondins (TSPs) are a family of five proteins that are involved in the tissue remodeling that is associated with embryonic development, wound healing, synaptogenesis, and neoplasia. These proteins mediate the interaction of normal and neoplastic cells with the extracellular matrix and surrounding tissue. In the tumor microenvironment, TSP-1 has been shown to suppress tumor growth by inhibiting angiogenesis and by activating transforming growth factor beta. TSP-1 inhibits angiogenesis through direct effects on endothelial cell migration and survival, and through effects on vascular endothelial cell growth factor bioavailability. In addition, TSP-1 may affect tumor cell function through interaction with cell surface receptors and regulation of extracellular proteases. Whereas the role of TSP-1 in the tumor microenvironment is the best characterized, the other TSPs may have similar functions. (Part of a Multi-author Review).

Interruption of homologous desensitization in cyclic guanosine 3',5'-monophosphate signaling restores colon cancer cytostasis by bacterial enterotoxins

Bacterial diarrheagenic heat-stable enterotoxins induce colon cancer cell cytostasis by targeting guanylyl cyclase C (GCC) signaling. Anticancer actions of these toxins are mediated by cyclic guanosine 3',5'-monophosphate (cGMP)-dependent influx of Ca2+ through cyclic nucleotide-gated channels. However, prolonged stimulation of GCC produces resistance in tumor cells to heat-stable enterotoxin-induced cytostasis. Resistance reflects rapid (tachyphylaxis) and slow (bradyphylaxis) mechanisms of desensitization induced by cGMP. Tachyphylaxis is mediated by cGMP-dependent protein kinase, which limits the conductance of cyclic nucleotide-gated channels, reducing the influx of Ca2+ propagating the antiproliferative signal from the membrane to the nucleus. In contrast, bradyphylaxis is mediated by cGMP-dependent allosteric activation of phosphodiesterase 5, which shapes the amplitude and duration of heat-stable enterotoxin-dependent cyclic nucleotide accumulation required for cytostasis. Importantly, interruption of tachyphylaxis and bradyphylaxis restores cancer cell cytostasis induced by heat-stable enterotoxins. Thus, regimens that incorporate cytostatic bacterial enterotoxins and inhibitors of cGMP-mediated desensitization offer a previously unrecognized therapeutic paradigm for treatment and prevention of colorectal cancer.

Proliferative signaling by store-operated calcium channels opposes colon cancer cell cytostasis induced by bacterial enterotoxins

Guanylyl cyclase C and accumulation of cGMP induced by bacterial heat-stable enterotoxins (STs) promote colon cancer cell cytostasis, serving as a tumor suppressor in intestine. Conversely, capacitative calcium entry through store-operated calcium channels (SOCs) is a key signaling mechanism that promotes colon cancer cell proliferation. The present study revealed that proliferative signaling by capacitative calcium entry through SOCs opposes and is reciprocally coupled to cytostasis mediated by guanylyl cyclase C in T84 human colon carcinoma cells. Elimination of capacitative calcium entry employing 2-aminoethoxydiphenylborate (2-APB), a selective inhibitor of SOCs, potentiated cytostasis induced by ST. Opposition of ST-induced cytostasis by capacitative calcium entry reflects reciprocal inhibition of guanylyl cyclase C signaling. Calcium entry through SOCs induced by the calcium-ATPase inhibitor thapsigargin or the receptor agonists UTP or carbachol inhibited guanylyl cyclase C-dependent cGMP accumulation. This effect was mimicked by the calcium ionophore ionomycin and blocked by 2-APB and intracellular 1,2-bis(o-amino-5,5'-dibromophenoxy)ethane-N,N,N',N'-tetraacetic acid-acetoxymethyl ester (BAPTA-AM), a chelator of calcium. Moreover, regulation by capacitative calcium entry reflected ligand-dependent sensitization of guanylyl cyclase C to inhibition by that cation. Although basal catalytic activity was refractory, ST-stimulated guanylyl cyclase C was inhibited by calcium, which antagonized binding of magnesium to allosteric sites required for receptor-effector coupling. These observations demonstrate that reciprocal regulation of guanylyl cyclase C signaling by capacitative calcium entry through SOCs represents one limb of a coordinated mechanism balancing colon cancer cell proliferation and cytostasis. They suggest that combining guanylyl cyclase C agonists and SOC inhibitors offers a novel paradigm for cGMP-directed therapy and prevention for colorectal tumors.

Reciprocal regulation and integration of signaling by intracellular calcium and cyclic GMP

Calcium and guanosine-3',5'-cyclic monophosphate (cGMP) are second messenger molecules that regulate opposing physiological functions, reflected in the reciprocal regulation of their intracellular concentrations, in many systems. Indeed, cGMP and Ca2+ constitute discrete points of integration between multiple cell signaling cascades in both convergent and parallel pathways. This chapter describes the molecular mechanisms regulating intracellular Ca2+ and cGMP, and their integration in specific cellular responses.

Guanylyl cyclase is an ATP sensor coupling nitric oxide signaling to cell metabolism

Defending cellular integrity against disturbances in intracellular concentrations of ATP ([ATP](i)) is predicated on coordinating the selection of substrates and their flux through metabolic pathways (metabolic signaling), ATP transfer from sites of production to utilization (energetic signaling), and the regulation of processes consuming energy (cell signaling). Whereas NO and its receptor, soluble guanylyl cyclase (sGC), are emerging as key mediators coordinating ATP supply and demand, mechanisms coupling this pathway with metabolic and energetic signaling remain undefined. Here, we demonstrate that sGC is a nucleotide sensor whose responsiveness to NO is regulated by [ATP](i). Indeed, ATP inhibits purified sGC with a K(i) predicting >60% inhibition of NO signaling in cells maintaining physiological [nucleotide](i). ATP inhibits sGC by interacting with a regulatory site that prefers ATP > GTP. Moreover, alterations in [ATP](i), by permeabilization and nucleotide clamping or inhibition of mitochondrial ATP synthase, regulate NO signaling by sGC. Thus, [ATP](i) serves as a "gain control" for NO signaling by sGC. At homeostatic [ATP](i), NO activation of sGC is repressed, whereas insults that reduce [ATP](i,) derepress sGC and amplify responses to NO. Hence, sGC forms a key synapse integrating metabolic, energetic, and cell signaling, wherein ATP is the transmitter, allosteric inhibition the coupling mechanism, and regulated accumulation of cGMP the response.

Functional and molecular characterization of beta-adrenoceptors in the internal anal sphincter

The purpose of the present study was to characterize different beta-adrenoceptors (beta-ARs) and determine their role in the spontaneously tonic smooth muscle of the internal anal sphincter (IAS). The beta-AR subtypes in the opossum IAS were investigated by functional in vitro, radioligand binding, Western blot, and reverse transcription-polymerase chain reaction (RT-PCR) studies. ZD 7114 [(S)-4-[2-hydroxy-3-phenoxypropylaminoethoxy]-N-(2-methoxyethyl)phenoxyacetamide], a selective beta(3)-AR agonist, caused a potent and concentration-dependent relaxation of the IAS smooth muscle that was antagonized by the beta(3)-AR antagonist SR 59230A [1-(2-ethylphenoxy)-3-[[(1S)-1,2,3,4-tetrahydro-1-naphthalenyl]amino]-(2S)-2-propanol hydrochloride]. Conversely, the IAS smooth muscle relaxation caused by beta(1)- and beta(2)-AR agonists (xamoterol and procaterol, respectively) was selectively antagonized by their respective antagonists CGP 20712 [(+/-)-2-hydroxy-5-[2-[[2-hydroxy-3-[4-[1-methyl-4-(trifluoromethyl)-1H-imidazol-2-yl]phenoxy]propyl]amino]ethoxy]-benzamide methanesulfonate salt] and ICI 118551. Saturation binding of [(125)I]iodocyanopindolol to beta-AR subtypes revealed the presence of a high-affinity site (K(d1) = 96.4 +/- 8.7 pM; B(max1) = 12.5 +/- 0.6 fmol/mg protein) and a low-affinity site (K(d2) = 1.96 +/- 1.7 nM; B(max2) = 58.7 +/- 4.3 fmol/mg protein). Competition binding with selective beta-AR antagonists revealed that the high-affinity site correspond to beta(1)/beta(2)-AR and the low affinity site to beta(3)-AR. Receptor binding data suggest the predominant presence of beta(3)-AR over beta(1)/beta(2)-AR. Western blot studies identified beta(1)-, beta(2)-, and beta(3)-AR subtypes. The presence of beta(1)-, beta(2)-, and beta(3)-ARs was further demonstrated by mRNA analysis using RT-PCR. The studies demonstrate a comprehensive functional and molecular characterization of beta(1)-, beta(2)-, and beta(3)-ARs in IAS smooth muscle. These studies may have important implications in anorectal and other gastrointestinal motility disorders.

Bacterial enterotoxins are associated with resistance to colon cancer

One half million patients suffer from colorectal cancer in industrialized nations, yet this disease exhibits a low incidence in under-developed countries. This geographic imbalance suggests an environmental contribution to the resistance of endemic populations to intestinal neoplasia. A common epidemiological characteristic of these colon cancer-spared regions is the prevalence of enterotoxigenic bacteria associated with diarrheal disease. Here, a bacterial heat-stable enterotoxin was demonstrated to suppress colon cancer cell proliferation by a guanylyl cyclase C-mediated signaling cascade. The heat-stable enterotoxin suppressed proliferation by increasing intracellular cGMP, an effect mimicked by the cell-permeant analog 8-br-cGMP. The antiproliferative effects of the enterotoxin and 8-br-cGMP were reversed by L-cis-diltiazem, a cyclic nucleotide-gated channel inhibitor, as well as by removal of extracellular Ca(2+), or chelation of intracellular Ca(2+). In fact, both the enterotoxin and 8-br-cGMP induced an L-cis-diltiazem-sensitive conductance, promoting Ca(2+) influx and inhibition of DNA synthesis in colon cancer cells. Induction of this previously unrecognized antiproliferative signaling pathway by bacterial enterotoxin could contribute to the resistance of endemic populations to intestinal neoplasia, and offers a paradigm for targeted prevention and therapy of primary and metastatic colorectal cancer.

Paraneoplastic pemphigus in children and adolescents

BACKGROUND

Paraneoplastic pemphigus (PNP) is an autoimmune mucocutaneous disease associated with specific B-cell lymphoproliferative neoplasms. There has been an increasing number of individual reports in the childhood and adolescent population.

OBJECTIVES

To examine the clinical and immunopathological features of PNP occurring in children and adolescents.

PATIENTS AND METHODS

We analysed the clinical and immunopathological findings of 14 patients under the age of 18 years with a confirmed diagnosis of PNP. Sera from all patients were analysed by indirect immunofluorescence (IF) and immunoprecipitation for plakin autoantibodies, immunoblotting for detection of plectin autoantibodies, and enzyme-linked immunosorbent assay (ELISA) for the detection of desmoglein (Dsg) 1 and Dsg3 autoantibodies.

RESULTS

Severe oral mucositis was observed in all patients, and lichenoid cutaneous lesions in eight of 14 patients. The average age at presentation was 13 years. Striking findings included: pulmonary destruction leading to bronchiolitis obliterans in 10 patients, association with Castleman's disease in 12 patients, and a fatal outcome in 10 patients. The underlying neoplasm was occult in 10 patients. Histological findings include lichenoid and interface dermatitis with variable intraepithelial acantholysis. Deposition of IgG and C3 in the mouth and skin by direct IF was not found in some cases, but indirect IF detected IgG autoantibodies in all cases. Immunoprecipitation revealed IgG autoantibodies against desmoplakin I, envoplakin and periplakin in all cases, and against desmoplakin II and the 170-kDa antigen in 13 and 10 patients, respectively. Dsg3 and Dsg1 autoantibodies were present in 10 and three patients, respectively, and plectin autoantibodies in 13 patients.

CONCLUSIONS

PNP in children and adolescents is most often a presenting sign of occult Castleman's disease. It presents with severe oral mucositis and cutaneous lichenoid lesions. Serum autoantibodies against plakin proteins were the most constant diagnostic markers. Pulmonary injury appears to account for the very high mortality rates observed.

Soluble guanylate cyclase is allosterically inhibited by direct interaction with 2-substituted adenine nucleotides

Nitric oxide (NO), the principal endogenous ligand for soluble guanylate cyclase (sGC), stimulates that enzyme and accumulation of intracellular cGMP, which mediates many of the (patho) physiological effects of NO. Previous studies demonstrated that 2-substituted adenine nucleotides, including 2-methylthioATP (2MeSATP) and 2-chloroATP (2ClATP), allosterically inhibit guanylate cyclase C, the membrane-bound receptor for the Escherichia coli heat-stable enterotoxin in the intestine. The present study examined the effects of 2-substituted adenine nucleotides on crude and purified sGC. 2-Substituted nucleotides inhibited basal and NO-activated crude and purified sGC, when Mg2+ served as the substrate cation cofactor. Similarly, 2-substituted adenine nucleotides inhibited those enzymes when Mn2+, which activates sGC in a ligand-independent fashion, served as the substrate cation cofactor. Inhibition of sGC by 2-substituted nucleotides was associated with a decrease in Vmax, consistent with a noncompetitive mechanism. In contrast to guanylate cyclase C, 2-substituted nucleotides inhibited sGC by a guanine nucleotide-independent mechanism. These studies demonstrate that 2-substituted adenine nucleotides allosterically inhibit basal and ligand-stimulated sGC. They support the suggestion that allosteric inhibition by adenine nucleotides is a general characteristic of the family of guanylate cyclases. This allosteric inhibition is mediated by direct interaction of adenine nucleotides with sGC, likely at the catalytic domain in a region outside the substrate-binding site.

Nitric oxide activation of soluble guanylyl cyclase reveals high and low affinity sites that mediate allosteric inhibition by calcium

Cyclic GMP (cGMP) and Ca(2+) regulate opposing mechanisms in (patho)physiological processes reflected in the reciprocal regulation of their intracellular concentrations. Although mechanisms by which cGMP regulates [Ca(2+)](i) have been described, those by which Ca(2+) regulates [cGMP](i) are less well understood. In the present study, Ca(2+) inhibited purified sGC activated by sodium nitroprusside (SNP), a precursor of nitric oxide (NO), employing Mg-GTP as substrate in a concentration-dependent fashion, but was without effect on basal enzyme activity. Ca(2+) inhibited sGC stimulated by protoporphyrin IX or YC-1 suggesting that inhibition was not NO-dependent. In contrast, Ca(2+) was without effect on sGC activated by SNP employing Mn-GTP as substrate, demonstrating that inhibition did not reflect displacement of heme from sGC. Ligand activation of sGC unmasked negative allosteric sites of high (K(i) similar 10(-7) M) and low (K(i) approximately 10(-5) M) affinity for Ca(2+) that mediated noncompetitive and uncompetitive inhibition, respectively. Free Mg(2+) in excess of substrate did not alter the concentration-response relationship of Ca(2+) inhibition at high affinity sites, but produced a rightward shift in that relationship at low affinity sites. Similarly, Ca(2+) inhibition at high affinity sites was noncompetitive, whereas inhibition at low affinity sites was competitive, with respect to free Mg(2+). Purified sGC specifically bound (45)Ca(2+) in the presence of a 1000-fold excess of Mg(2+) and in the absence of activating ligands. These data suggest that sGC is a constitutive Ca(2+) binding protein whose allosteric function is conditionally dependent upon ligand activation.

Guanylyl cyclases and signaling by cyclic GMP

Guanylyl cyclases are a family of enzymes that catalyze the conversion of GTP to cGMP. The family comprises both membrane-bound and soluble isoforms that are expressed in nearly all cell types. They are regulated by diverse extracellular agonists that include peptide hormones, bacterial toxins, and free radicals, as well as intracellular molecules, such as calcium and adenine nucleotides. Stimulation of guanylyl cyclases and the resultant accumulation of cGMP regulates complex signaling cascades through immediate downstream effectors, including cGMP-dependent protein kinases, cGMP-regulated phosphodiesterases, and cyclic nucleotide-gated ion channels. Guanylyl cyclases and cGMP-mediated signaling cascades play a central role in the regulation of diverse (patho)physiological processes, including vascular smooth muscle motility, intestinal fluid and electrolyte homeostasis, and retinal phototransduction. Topics addressed in this review include the structure and chromosomal localization of the genes for guanylyl cyclases, structure and function of the members of the guanylyl cyclase family, molecular mechanisms regulating enzymatic activity, and molecular sequences coupling ligand binding to catalytic activity. A brief overview is presented of the downstream events controlled by guanylyl cyclases, including the effectors that are regulated by cGMP and the role that guanylyl cyclases play in cell physiology and pathophysiology.