United States

Contribution of β-cell GLUT2 to systemic glucose homeostasis remains controversial in humans. For example, recent publications indicate that GLUT2 is not a major glucose transporter in β-cells in humans and therefore may not be involved in regulating systemic glucose homeostasis, which is in strong contrast to its previously assumed contribution to influencing systemic glucose balance. Although global Glut2 knockout mice develop diabetes, the contribution of β-cell Glut2 toward this phenotype is unknown. To determine the role of β-cell Glut2 in systemic glucose homeostasis, we crossed Glut2LoxP/LoxP mice with INSCreERT2 mouse strain to obtain mice that will potentially lack Glut2 specifically in β-cells (β-Glut2 KO) after administration of tamoxifen (100 mg/kg, i.p., once daily for five days) to induce the Cre-Lox recombination. We measured 6 h fasting blood glucose levels, glucose tolerance, and glucose-induced insulin secretion in the β-Glut2 KO mice. We observed that the KO mice had normal fasting blood glucose levels (male: 194.2 ±9.3 vs 192.0 ±3.5; female: 177.3 ±8.5 vs 157.3 ±9.8 mg/dL, Control vs. β-Glut2 KO). Similarly, the β-Glut2 KO mice exhibited normal glucose tolerance following oral administration of 60 mg glucose (Area under the curve for glucose tolerance, male: 39,911 ±1,632 vs. 39,633 ±1,275; female: 47,321 ±3,294 vs. 43,673 ±2,677 mg/dL*min, Control vs. β-Glut2 KO). Moreover, the KO mice had normal glucose-stimulated insulin secretion (baseline fasting plasma insulin levels: male - 0.84 ±0.14 vs. 0.5 ±0.01; female - 0.45 ±0.09 vs 0.48 ±0.1; plasma insulin levels 20 min. after oral glucose administration: male - 2.39 ±0.13 vs 2.48 ±0.51; female - 1.63 ±0.3 vs 1.11 ±0.12 ng/ml, Control vs. β-Glut2 KO). We had validated the loss of β-cell Glut2 using mRNA in situ hybridization. Altogether, our findings indicate that β-cell Glut2 is not essential for regulating systemic glucose homeostasis in mice, which was also observed recently with human β-cells. Therefore, the currently assumed major role of β-cell GLUT2 in directly influencing blood glucose levels needs to be reexamined to better understand the pathophysiology of impaired glucose homeostasis in diabetes.

ENDO 2022

Loss of β-Cell Glut2 Does Not Affect Systemic Glucose Homeostasis in Mice

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technical paper

Glucagon stimulates glycogenolysis and gluconeogenesis in liver resulting in increased hepatic glucose output. Thus, interrupting glucagon signaling in liver reduces blood glucose levels in animal models and individuals with diabetes. However, interrupting glucagon signaling also leads to hyperaminoacidemia and proliferation of glucagon secreting alpha cells, evidence of an endocrine liver-alpha cell axis. Among the high amino acids, we previously identified high glutamine levels are required for alpha cell proliferation. We recently found that glutaminase (GLS) is expressed in alpha cells at much higher levels than any other pancreatic endocrine cells. Additionally, mouse pancreatic islets cultured in high amino acid containing media and treated with the small molecule inhibitor of GLS (CB839) have reduced alpha cell proliferation (Vehicle: 7.6 ± 2.2%, 0.1µM CB839: 0.11 ± 0.05%**, 10µM: 0.02 ± 0.01%**; n=3-4, **p < 0.01). To further characterize the role of glutamine metabolism in glutamine-induced alpha cell proliferation, GLS activity was specifically knocked out in mouse alpha cells by breeding Gcg-CRE ERT2 with Glsflox mice (aGlsKO). Targeted deletion of Gls expression in most alpha cells was confirmed by staining for GLS and glucagon (aGlsWT: 95% GLS+, aGlsKO: 18% GLS+). Mice were treated with a glucagon receptor monoclonal antibody (GCGR mAb/mAb-4) for 10 days or with isotype control IgG. aGlsWT mice treated with GCGR mAb have robust alpha cell proliferation while aGlsKO mice treated with GCGR mAb for 10 days showed a 4.5-fold decrease in alpha cell proliferation and were similar to mice treated with the control IgG (aGlsWT Ab: 15.7 ± 3.6% alpha cell proliferation, aGlsWT IgG: 1.0 ± 0.4%***, aGlsKO Ab: 3.4 ± 0.6%**; n=4-6, ***p < 0.001). In addition, aGlsWT mice treated with GCGR mAb showed a robust activation of mTOR in alpha cells as measured by phospho-S6 expression while this was lost in aGlsKO mice treated with GCGR mAb. Induced expression of the mTOR-dependent glutamine transporter SLC38A5 was also lost (aGlsWT Ab: 25.0 ± 4.8% alpha cell SLC38A5 expression, aGlsWT IgG: 0.40 ± 0.27%***, aGlsKO Ab: 3.7 ± 3.5%***, n= 2-4, ***p < 0.001). Similar results on proliferation and mTOR activation in alpha cells were observed after 4 weeks of GCGR mAb treatment. Together these data suggest a critical role for glutamine metabolism via glutaminase in alpha cell proliferation.

Genetic Inactivation of Glutaminase Reduces Amino Acid Induced Alpha Cell Proliferation

Oxidative stress-induced lipid peroxidation generates oxidized phospholipids (OxPL), such as oxidized phosphatidylcholine, that are pro-inflammatory moieties present on oxidized low density lipoproteins and apoptotic cells. OxPL have been implicated in the pathogenesis of cardiovascular, neurological, autoimmune, liver, and lung diseases. It has been shown earlier that OxPL decrease bone formation. Natural antibodies (NAb) produced by B-1 lymphocytes, bind OxPL and prevent their inflammatory activity. The NAb E06 blocks oxidized phosphatidylcholine, and transgenic expression of a single chain (scFv) form of the antigen-binding domain of E06 IgM (E06-scFv) prevents many age-associated diseases, such as atherosclerosis, non-alcoholic steatohepatitis and age-related bone loss. OxPL are also implicated in the pathogenesis of the metabolic syndrome and diabetes by either causing insulin resistance, increasing macrophage infiltration and inflammation in white adipose tissue, decreasing insulin gene expression, and/or causing death of pancreatic beta cells through induction of oxidative stress and amyloid protein misfolding. Consistent with this evidence, NAb produced by B-1b lymphocytes are protective against obesity associated inflammation, glucose intolerance, and insulin resistance. In the work reported here, we have investigated the impact of oxidized phosphatidylcholine on glucose metabolism and age–related glucose intolerance. To this end, we aged chow-fed female and male C57BL/6 E06-scFv transgenic mice (and their WT littermates) up to 22 and 24 months. Both male and female E06-scFv transgenic mice accumulated less fat mass than WT littermates during aging, as determined by sequential body composition measurements by DXA. Intraperitoneal glucose tolerance test, performed at 10 and at 15 months of age, showed that glucose tolerance was greater in both male and female E06-ScFv transgenic mice than WT littermates and did not differ from the glucose tolerance of young mice. Insulin sensitivity, measured by insulin tolerance test, was increased in 4- and 10-month-old old transgenic females and in 15-month-old transgenic males. There was no difference in food consumption calculated over 5 days or the production of glucose after pyruvate infusion, indicating similar liver gluconeogenesis in both strains. Physical activity or energy expenditure, measured by indirect calorimetry in 11-month-old females, was indistinguishable between transgenic and WT mice. However, E06-scFv transgenic mice exhibited a significant increase in the respiratory exchange ratio, indicating that utilization of glucose was the main metabolic source under basal conditions. Collectively, these results show that blocking oxidized phosphatidylcholine improves age–related glucose intolerance in mice fed a normal diet; hence, OxPL are major culprits of the aging-associated glucose intolerance. Therefore, targeting OxPL with a neutralizing antibody represents a novel therapeutic intervention that may simultaneously ameliorate several age-associated diseases, including the metabolic syndrome and diabetes.


A Natural Antibody Against Oxidized Phospholipids Improves Glucose Metabolism in Aging Mice

Excess blood lipids increase the total intramyocellular (IMC) lipid content and ectopic fat storage resulting in lipotoxicity and insulin resistance in skeletal muscle, which is one of the main targets of insulin whose action is central for the maintenance of glucose homeostasis. Consumption of a diet high in fat and refined sugars, a Western Diet (WD), has been shown to activate mineralocorticoid receptors (MRs) to promote insulin resistance. However, our understanding of the precise mechanisms by which enhanced MR activation promotes skeletal muscle insulin resistance remains unclear. In this study we investigated the roles and mechanisms by which enhanced MR signaling in soleus muscle promotes ectopic lipid accumulation and related insulin resistance in diet-induced obesity. Six week-old C57BL6J mice were fed either a mouse chow diet or WD with or without spironolactone (1 mg/kg/day) for 16 weeks. Spironolactone attenuated 16 weeks of WD - induced in vivo glucose intolerance and improved soleus insulin metabolic signaling (protein kinase B and AMP kinase α pathways). Improved insulin sensitivity was accompanied by increased Glut-4 expression in conjunction with decreased IMC lipid content and reduced free fatty acid (FFA) levels and CD36 expression in soleus skeletal muscle tissue. Related to this, miR-99a was identified to negatively target CD36(www.targetscan.org/vert_72/) and elevated CD36 induced excessive FFA uptake, ectopic lipid accumulation, as well as systemic and tissue insulin resistance. Furthermore, in skeletal muscle cells spironolactone prevented enhanced MR signaling mediated reduction of miR-99a and related increased CD36. These data indicate that inhibition of MR activation with spironolactone reversed diet - induced reduction of miR-99a, thereby reducing CD36 expression, leading to reduced IMC lipid content and improved soleus insulin sensitivity.

Mineralocorticoid receptors mediate diet - induced lipid infiltration of skeletal muscle and insulin resistance

Insulin replacement therapy is lifesaving for insulin-dependent diabetic patients, but it comes with an ever-present threat of hypoglycemia, which can eventually cause ischemic events, arrhythmias, neurological damage, coma, or even death. Consequently, the risk of hypoglycemia remains the most significant obstacle that prevents insulin-dependent patients from attaining adequate metabolic control. One approach to solve this issue involves the co-injection of insulin and glucagon at a fixed ratio, which has been shown to improve glycemic control with prevention of hypoglycemia. The co-administration of both hormones is based on two known physiological processes: first, insulin is a potent inhibitor of glucagon activity, especially under hyperglycemic conditions, and second, glucagon overpowers insulin and stimulates hepatic glucose production under hypoglycemic circumstances. In this work, we took this concept further into developing an insulin/glucagon fusion protein that will provide glycemic control (by the insulin portion) while preventing hypoglycemia (through the glucagon portion). Because both hormones are known to be unstable and form amyloid-like fibrils, our approach consists of using a fibrillation-resistant single-chain insulin (SCI) analog fused to a novel fibrillation-resistant glucagon analog. These molecules were independently synthesized by Solid-Phase Peptide Synthesis (SPPS) and linked together from the C-Terminus of the glucagon analog to the N-Terminus of the SCI analog by trypsin-mediated ligation. By themselves or when fused, these ultra-stable analogs didn't form fibrils after one month of agitation at 37°C in PBS (pH 7.4). By contrast, native insulin started fibrillation at 12.14 ± 3.65 hours, and native glucagon at time 0. The glucagon analog was designed to be less potent than the native molecule to allow unopposed insulin activity while in hyperglycemia but maintaining full agonism to prevent hypoglycemia. The in vitro glucagon activity was measured by cAMP production in HEK293 expressing the glucagon receptor. The glucagon analog was determined to be a full agonist with an EC50 of 125.7 nM, a ~58-fold potency difference to the native molecule (2.175 nM). The fusion protein was tested in vitro and in vivo to determine the activities of both moieties when fused. The in vitro insulin activity of the fusion protein measured by traditional and in-cell western blot was comparable to the SCI alone. The in vitro glucagon activity of the fusion protein was also similar to the glucagon analog alone (EC50 151.2 nM), therefore validating our fusion approach. The in vivo insulin and glucagon activities are currently being tested by subcutaneous injection in diabetic (STZ) and normal rats. So far, both insulin and glucagon moieties have shown to be fully active, and hypoglycemia has not been observed in rats. Increasing doses studies are underway. We believe that this approach will allow the design of next-generation insulin treatments protected against hypoglycemia, ultra-stable, and amenable for multiplatform delivery.

Design of an Ultra-Stable Insulin/Glucagon Fusion Protein

Emerging evidence suggests an association between FSH and bone mass in peri- and postmenopausal women. The aim of the present study was to assess body composition parameters and hormone levels as risk factors for low bone mass in women with recent menopause. In this cross-sectional study, we analyzed biorepository samples from 139 postmenopausal women aged 42 to 68 years with no evidence of clinical CVD. Inclusion criteria were as follows: menopause, defined as last menstrual period at least 12 months of amenorrhea and/or 6 months or more of amenorrhea plus FSH levels ≥35 mIU/mL occurring after 40 years of age, and no use of hormone therapy (HT) in the past 3 month. BMD and body composition were assessed by dual-energy X-ray absorptiometry (DXA), SHBG and FSH levels were measured in all patients. Serum estradiol levels were measured by gas chromatography/tandem mass spectrometry assay (GC/MS/MS) in a subset of 57 participants and free estrogen index (FEI) was estimated by dividing estradiol by SHBG × 100. Low bone mass was considered osteoporosis and osteopenia. The mean age was 54.33±5.30 years and median time since menopause was 4 (2 - 9) years. The mean BMI was 26.73±4.38 kg/m² and 66% of participants were classified as overweight or obese. BMI, BMD and T-sc, lean mass index (LMI) and fat mass index (FMI) were lower, and SHBG was higher in women with FSH levels above the median values (83.6mUI/mL). FSH was inversely correlated with FEI (rho=-0.283, p=0.033) as well as with FMI (rho=-0.288, p=0.001) and LMI (rho=-0.186, p=0.029), but significance was lost after adjustment for estradiol levels (p=0.651).  In the univariate linear regression analysis, FSH, FEI, time since menopause, SHBG, FMI and LMI were significant predictors to total femur bone mass, explaining 3.8%, 11.9%, 7.4%, 14.7%, 19.7% and 8.4% of variance in BMD at this site, respectively. In the multivariate model, the association of FSH, time since menopause and FMI with hip bone mass was no longer significant after inclusion of FEI in the respective model. The present results indicate that the negative association between FSH levels and femoral BMD in postmenopausal women are influenced by endogenous estradiol levels, time since menopause and fat mass. Additional studies are needed in order to further analyze whether some direct effect of FSH on bone mass may be additive to the presence of low bone mass in this population.

Associations between bone mass, hormone levels and body composition in postmenopausal women

Background:
Liver transplantation is an established treatment for patients with end-stage liver disease. In 2021 more than 8,400 liver transplants were performed in the United States. Although successful transplantation can reverse many complications of end organ failure, disturbance of bone and mineral metabolism may persist, which can contribute substantially to morbidity and mortality. It is important to assess whether liver transplant patients are getting bone density screening and treatment.
Objective:
Our goal is to assess current practice in bone density screening in patients who have undergone liver transplant at our medical center, to identify if these patients are being screened for metabolic bone disease before and after transplant, and to improve management of such patients by initiating a provider work flow that is based on available data and evidence.
Study Design:
The first phase was a survey of the liver transplant team to assess the current protocol for screening. The second phase involved retrospective chart review of patients at our institution who had a liver transplant between October 2008 and April 2021. The findings will be used to create an institutional protocol for osteoporosis screening and management.
Results:
Survey results: 62.5% of liver transplant providers knew that guidelines or a protocol are being used to screen liver transplant recipients for osteoporosis. 75% said that dual-energy x-ray absorptiometry (DXA) scans are always obtained before liver transplantation, while 25% said they are sometimes obtained. There were mixed results regarding monitoring post transplant. All respondents agreed that creating a protocol for osteoporosis screening would improve outcomes of bone health in transplant patients.
Chart review results: We reviewed 243 liver transplant recipients between October 2008 and April 2021. After excluding duplicate transplants and those less than 18 years old, 234 patients were included in analysis. 59% of patients were men with a median age of 63.5. The most common etiologies of pre-transplant liver disease were Hepatocellular Carcinoma (29%), Hepatitis C (17%), alcoholic cirrhosis (16%) and NASH (5%). 72% of transplant patients had a DXA before transplant and 28% did not. Of those with a pre-transplant DXA, 28% had normal bone density, 50% had osteopenia, and 20% had osteoporosis. The remainder did not have data available. Among those with a diagnosis of osteoporosis pre-transplant, 41% received treatment while 56% did not receive any bone-specific therapy.
Discussion:
The majority of providers in our liver transplant team are aware of the need for bone health screening and treatment in liver transplant candidates. Most patients received a DXA prior to transplant however less than half of the patients with osteoporosis were started on treatment. Our study shows the need for developing an institutional work flow to optimize bone health in patients undergoing liver transplant.

Osteoporosis Screening of Liver Transplant Patients in a Tertiary Urban Medical Center

Background: Obesity is associated with relative growth hormone (GH) deficiency and increased fracture risk. We hypothesized that GH administration would improve bone endpoints in individuals with overweight/obesity.
Methods: 77 adults ages 18-65 years, BMI ≥25 kg/m², and BMD T- or Z-score ≤ -1.0 were randomized in a double-blind protocol to daily subcutaneous GH or placebo for 18 months, targeting IGF-1 in the upper quartile of the age-appropriate normal range. There was a post-treatment observation period from 18-24 months. DXA and high-resolution peripheral quantitative CT were performed at baseline, 18 months and 24 months. Volumetric quantitative CT was performed at baseline and 18 months. Results are reported as mean ±SD or mean (95% confidence interval).
Results: There were no pretreatment differences between the GH (n=39) and placebo groups (n=38), including mean age (48±12y), BMI (33.1±5.7kg/m²) and BMD at any site. Forty-nine subjects (47% female) completed 18 months. P1NP, osteocalcin and CTX increased (p<0.005) and visceral adipose tissue decreased (p=0.04) at 18 months in the GH vs placebo group. Hip and radius aBMD, spine and tibial vBMD, tibial cortical thickness, and radial and tibial failure load decreased at 18 months in the GH vs placebo group (p<0.05). During the post-treatment observation period (18 to 24 months), total radius aBMD and tibia cortical thickness increased in the GH vs placebo group (p<0.05); there was also a trend toward an increase in total hip aBMD in the GH vs placebo group (p=0.06). At 24 months, none of the differences between the GH and placebo groups remained significant. There was a higher incidence of numbness and tingling (33% vs 8%, p=0.01) and joint pain or stiffness (33% vs 5%, p=0.003) in the GH vs placebo group. There were no other differences in adverse events between groups.
Conclusions: We demonstrated that GH administration for 18 months to individuals with overweight/obesity and low BMD decreased some measures of BMD, bone microarchitecture, and bone strength compared with placebo. None of these differences remained significant after 6 months off therapy. A longer duration of treatment, or a longer duration of observation post-treatment, may be necessary to see the expected biphasic decline and then increase in BMD reflecting an expanding remodeling space followed by mineralization that has previously been seen with GH administration in other populations, including individuals with and without GH deficiency. Although future investigation of the effects of GH on bone is required to assess the true long-term impact on skeletal integrity as well as fracture reduction, our study suggests that GH administration for 18 months to adults with overweight/obesity does not improve BMD, bone microarchitecture, or bone strength.

Impact of GH Administration on Skeletal Endpoints in Adults with Overweight/Obesity

Osteoporosis is a common systemic skeletal disease that predominantly affects people older than 50 years and often co-occurs with dementia. Studies have been conducted to find out the relation between the two, but this is not well studied in the Vietnamese population. This study aimed to analyze the impact of osteoporosis on the risk of dementia in Vietnamese immigrants.
We identified 38(female(F) 26, male(M) 12) community-dwelling Vietnamese patients aged ≥ 55 seen at the cognitive assessment clinic in a community health center 1/2021-8/2021 through chart review. Because either DEXA was not performed or the results were unavailable, 23 patients (F 12, M 11) were excluded. We assigned the patients with normal cognitive tests results or a diagnosis of mild cognitive impairment to the control group and those diagnosed with dementia to the study group.
Among 15 patients, 10(F 9, M 1) patients were diagnosed with dementia. Seven patients (F 6, M 1) had osteoporosis. Five patients (F 5) were assigned to the control group, and two patients had osteoporosis. (OR 3.5000, P = 0.2736)
The odds of developing dementia were 3.5 higher given osteoporosis diagnosis than with no osteoporosis. These results suggested a positive association between osteoporosis and dementia in Vietnamese immigrants. More studies with a larger number of patients in this cohort are needed to investigate this further.

Osteoporosis Likely Increases the Risk of Dementia in Vietnamese Immigrants

While anorexia nervosa is associated with impaired skeletal integrity, less is known about the skeletal effects of atypical anorexia nervosa, in which psychological criteria for anorexia nervosa are met, but affected individuals are not low weight. Mean bone mineral density (BMD) is higher in atypical anorexia nervosa than in low-weight anorexia nervosa but lower than in healthy controls. However, it is unknown whether bone microarchitecture and strength are affected. We hypothesized that bone microarchitecture and estimated strength would be impaired in women with atypical anorexia nervosa.
This was a cross-sectional study of women ages 21-46 years (n=55): n=28 with atypical anorexia nervosa (body mass index (BMI) >18.5 kg/m²), n=27 healthy, normal weight, eumenorrheic controls. Exclusion criteria included use of oral contraceptives. Areal BMD (aBMD) was assessed by DXA. Volumetric BMD (vBMD), microarchitecture, and failure load (a bone strength estimate) at the distal tibia and radius were assessed by high-resolution peripheral quantitative CT.
Median(IQR) BMI was lower [19.4(18.6,20.2) vs 22.2(21.5,23.0), p<0.0001] and median serum 25OH vitamin D level was higher [31(24,39) vs 22(17,25), p=0.0001] in atypical anorexia nervosa than healthy controls. In the atypical anorexia nervosa group, 89% had a history of low weight, 21% had a history of overweight/obesity, 31% had current amenorrhea, and 88% had a history of amenorrhea; median duration of anorexia nervosa was 11(5,14) years.
Median lateral spine, total hip, femoral neck, and total radius aBMD Z-scores were lower in atypical anorexia nervosa than healthy controls [lateral spine: -1.1(-2.0,-0.1) vs -0.4(-0.7,0.4), total hip: -0.8(-1.3,0.2) vs 0.2(-0.4,0.7), femoral neck: -0.9(-1.4,0.1) vs -0.1(-0.9,0.6), radius: -0.2(-0.9,0.3) vs 0.1(-0.4,0.6); p≤0.04 for all]. At the tibia, median total, cortical, and trabecular vBMD; cortical thickness; trabecular bone volume fraction; and failure load were lower in atypical anorexia nervosa than healthy controls (p<0.05). At the radius, median trabecular number was lower and trabecular separation was higher in atypical anorexia nervosa than healthy controls (p≤0.04), but there was no difference in failure load between the groups. After controlling for baseline BMI, differences at the radius but not tibia remained significant. At the tibia and radius, median total vBMD, cortical vBMD, and cortical thickness were lower in atypical anorexia nervosa subjects with amenorrhea compared to healthy controls and to atypical anorexia nervosa subjects with eumenorrhea (p≤0.04).
Conclusions: We demonstrate that, despite normal weight, women with atypical anorexia nervosa have impaired vBMD, microarchitecture, and estimated strength compared to healthy controls, with differences more pronounced at the weight-bearing tibia vs non-weight-bearing radius. Individuals with amenorrhea had additional impairments in the non-weight-bearing radius, suggesting an effect of systemic estrogen deficiency. Our data suggest that current normal weight is not protective against impaired bone structure and strength in atypical anorexia nervosa.

Impairments in volumetric bone mineral density, bone microarchitecture, and estimated strength in women with atypical anorexia nervosa

Background: Adrenocortical cancer (ACC) is a rare endocrine malignancy frequently diagnosed at an advanced stage when prognosis is dismal. Mitotane, the only approved therapy for locally advanced or metastatic disease, is minimally effective, and recent clinical trials with multi-kinase inhibitors or immunotherapies have been disappointing. OR-449 is a potent, selective, and orally bioavailable small molecule antagonist to steroidogenic factor-1 (SF-1 or NR5A1), a nuclear receptor and a transcription factor essential for the growth and development of the adrenal gland. SF-1 was recently described as a candidate "master transcription factor" in adult ACC (1). We previously reported that OR-449, dosed orally at 30 mg/kg for 28 days, completely blocked the growth of SJ-ACC3, a pediatric ACC patient-derived tumor xenograft (PDX), in immunocompromised mice. To help identify biomarkers for following the action of OR-449 in patient tumors, we evaluated a second pediatric ACC PDX, SW1939, which has high SF-1 expression and responded to OR-449 (10, 30 or 100 mg/kg) with inhibition of tumor growth and improved event-free survival over 24 days of dosing (an event is a 4-fold increase in tumor volume). Methods: We first measured circulating steroids, steroid precursors and steroid sulfates in SW1939 tumor-bearing mice with or without OR-449 treatment using liquid chromatography/tandem mass spectrometry. Second, we investigated common pathways of gene regulation by OR-449 in SW1939 and SJ-ACC3 tumors by RNAseq after seven days of dosing (100 mg/kg or 30 mg/kg, respectively). Results: Cortisol, DHEAS, steroid precursors (11-deoxycortisol, 17OH-progesterone, 17OH-pregnenolone) and sulfated Δ5 steroid precursors (pregnenolone sulfate, 17OH-pregnenolone sulfate, androstenediol-sulfate) were elevated in serum from SW1939 tumor-bearing mice compared to CD-1 non tumor-bearing mice, consistent with tumor-derived origin. Moreover, DHEAS, pregnenolone sulfate, 17OH-pregnenolone sulfate and androstenediol-sulfate were significantly suppressed (12-fold, 7.6-fold, 10.6-fold and 4.4-fold, respectively) following administration of OR-449 (100 mg/kg/day for 24 days) in SW1939 tumor-bearing mice. Final tumor weights were ~2-fold lower than controls, indicating that circulating steroid reduction was disproportionately greater than the change in tumor volume. Global gene expression was significantly altered following 7-day exposure to OR-449 in both tumors. Significantly, PAPSS2 and SULT2A1 within the sulfation pathway were down-regulated in both SW1939 (2.3-fold and 1.2-fold, respectively) and SJ-ACC3 (1.6-fold and 5-fold, respectively). Conclusions: OR-449 reduces steroid production, alters gene expression, and suppresses growth of two PDX models of ACC in mice. Tumor gene expression and steroid regulation by OR-449 are currently under investigation in other pediatric and adult ACC PDX models to evaluate these endpoints as potential biomarkers of SF-1 receptor engagement for initial clinical trials of OR-449 in ACC. Reference: (1) Corces et al., Science. 2018 Oct 26;362(6413): eaav1898; Reddy et al., Sci Adv. 2021 Nov 26;7(48): eabf6123.

Loss of β-Cell Glut2 Does Not Affect Systemic Glucose Homeostasis in Mice

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