Analysis of Outpatient Adherence in 45,237 Patients Referred by an Emergency Department to Surgical Clinics.

INTRODUCTION: This study examines referral patterns to surgical clinics from the emergency department and the impact of sociodemographic factors on adherence. METHODS: Patients from 2017 to 2021 were identified who had a referral placed to surgical specialties from the ED. The primary outcome was the proportion of patients who had a referral to surgery placed during an ED visit but who showed up to surgery clinic visit within 60 days of referral placement. Univariate and multivariate analysis was performed. RESULTS: Referrals were made for 45,237 patients overall and 4130 for general surgery specifically. 44% showed up to general surgery clinic visit. In univariate and multivariate analysis, those who showed up to clinic were older, tended to be female, had a lower social economic status, had Medicaid or Medicare insurance and had more comorbidities compared to those who did not show up. Asians and Hispanics were more likely to show up to clinic compared to Whites. CONCLUSIONS: Assigning navigators in the ED to follow-up with patients who are younger and healthier, with private insurances who have existing PCPs to ensure they follow up as advised is a potential targeted intervention to improve clinic adherence.

Cyclin-dependent kinase 4/6 inhibitors require an arcuate-to-paraventricular hypothalamus melanocortin circuit to treat diet-induced obesity.

The arcuate nucleus (ARC) of the hypothalamus comprises two antagonistic neuron populations critical for energy balance, namely, the anorexigenic pro-opiomelanocortin (POMC) and the orexigenic agouti-related peptide (AgRP) neurons that act as agonists and antagonists, respectively, for neurons expressing the type IV melanocortin receptor (MC4R) (Andermann ML and Lowell BB. Neuron 95: 757-778, 2017). MC4R activation increases energy expenditure and decreases food intake during positive energy balance states to prevent diet-induced obesity (DIO). Work from our group identified aberrant neuronal cell cycle events both as a novel biomarker and druggable target in the ARC for the treatment of DIO, demonstrating pharmacological restoration of retinoblastoma protein function in the ARC using cyclin-dependent kinase 4/6 (CDK4/6) inhibitors could treat DIO in mice by increasing lipid oxidation to selectively decrease fat mass. However, the role of CDK4/6 inhibitors on food intake was not examined. Four-week-old Mc4r-loxTB mice were continuously administered high-fat diet (60% kcal fat). At 8 wk of age, animals were administered 60 mg/kg abemaciclib orally or a saline control and monitored every 2 wk for fat mass changes by MRI. At 11 wk of age, all animals were injected bilaterally in the paraventricular hypothalamus with AAV8 serotype virus expressing a Cre-mCherry and monitored for another 5 wk. Restoration of Mc4r expression in the paraventricular hypothalamic nucleus (PVN/PVH) reduced food intake in hyperphagic obese mice when given CDK4/6 inhibitor therapy. The reduced food intake was responsible for reduced fat mass in mice treated with abemaciclib. These results indicate that targeting POMC neurons could be an effective strategy in treating diet-related obesity.NEW & NOTEWORTHY We have defined some of the necessary components to prevent high-fat diet-induced obesity at the molecular and cellular level. Within POMC neurons, the retinoblastoma protein must remain active and prevented from phosphoinactivation by cyclin-dependent kinases. The downstream neurons within the PVH must also properly express MC4R for the circuit to appropriately regulate feeding behavior.

Targeted Inhibition of the E3 Ligase SCFSkp2/Cks1 Has Antitumor Activity in RB1-Deficient Human and Mouse Small-Cell Lung Cancer.

The RB1 tumor suppressor gene is mutated in highly aggressive tumors including small-cell lung cancer (SCLC), where its loss, along with TP53, is required and sufficient for tumorigenesis. While RB1-mutant cells fail to arrest at G1-S in response to cell-cycle restriction point signals, this information has not led to effective strategies to treat RB1-deficient tumors, as it is challenging to develop targeted drugs for tumors that are driven by the loss of gene function. Our group previously identified Skp2, a substrate recruiting subunit of the SCF-Skp2 E3 ubiquitin ligase, as an early repression target of pRb whose knockout blocked tumorigenesis in Rb1-deficient prostate and pituitary tumors. Here we used genetic mouse models to demonstrate that deletion of Skp2 completely blocked the formation of SCLC in Rb1/Trp53-knockout mice (RP mice). Skp2 KO caused an increased accumulation of the Skp2-degradation target p27, a cyclin-dependent kinase inhibitor, which was confirmed as the mechanism of protection by using knock-in of a mutant p27 that was unable to bind to Skp2. Building on the observed synthetic lethality between Rb1 and Skp2, we found that small molecules that bind/inhibit Skp2 have in vivo antitumor activity in mouse tumors and human patient-derived xenograft models of SCLC. Using genetic and pharmacologic approaches, antitumor activity was seen with Skp2 loss or inhibition in established SCLC primary lung tumors, in liver metastases, and in chemotherapy-resistant tumors. Our data highlight a downstream actionable target in RB1-deficient cancers, for which there are currently no targeted therapies available. SIGNIFICANCE: There are no effective therapies for SCLC. The identification of an actionable target downstream of RB1, inactivated in SCLC and other advanced tumors, could have a broad impact on its treatment.

Neuronal Cell Cycle Events Link Caloric Intake to Obesity.

Obesity is a neurological disorder that operates by favoring energy storage within adipose depots and increased caloric intake. Most cases of human obesity are acquired without any underlying genetic basis. Here, we suggest that obesity can impair the function of some hypothalamic neurons critical to body weight regulation. Genetic ablation of the retinoblastoma (Rb) gene within pro-opiomelanocortin (POMC) neurons leads to death of the neurons and subsequent obesity. The Rb protein (pRb), a key inhibitor of the cell cycle, can also be inactivated by cyclin dependent kinase (CDK)-mediated phosphorylation. Extensive development led to the production of FDA-approved CDK4/6 inhibitors. Based on our own results, we propose that maintaining or re-instating pRb function using CDK4/6 inhibitors are potentially effective treatments of diet-induced obesity (DIO).

Genes and Pathways Promoting Long-Term Liver Repopulation by Ex Vivo hYAP-ERT2 Transduced Hepatocytes and Treatment of Jaundice in Gunn Rats.

Hepatocyte transplantation is an attractive alternative to liver transplantation. Thus far, however, extensive liver repopulation by adult hepatocytes has required ongoing genetic, physical, or chemical injury to host liver. We hypothesized that providing a regulated proliferative and/or survival advantage to transplanted hepatocytes should enable repopulation in a normal liver microenvironment. Here, we repopulated livers of DPPIV- (dipeptidyl peptidase-4) rats and Ugt1a1 (uridinediphosphoglucuronate glucuronosyltransferase 1a1)-deficient Gunn rats (model of Crigler-Najjar syndrome type 1), both models without underlying liver injury, for up to 1 year by transplanting lenti-hYAP-ERT2 (mutated estrogen receptor ligand-binding domain 2)-transduced hepatocytes (YAP-Hc). Yap (yes-associated protein) nuclear translocation/function in YAP-Hc was regulated by tamoxifen. Repopulating YAP-Hc and host hepatocytes were fluorescence-activated cell sorting-purified and their transcriptomic profiles compared by RNAseq. After 1 year of liver repopulation, YAP-Hc clusters exhibited normal morphology, integration into hepatic plates and hepatocyte-specific gene expression, without dysplasia, dedifferentiation, or tumorigenesis. RNAseq analysis showed up-regulation of 145 genes promoting cell proliferation and 305 genes suppressing apoptosis, including hepatocyte growth factor and connective tissue growth factor among the top 30 in each category and provided insight into the mechanism of cell competition that enabled replacement of host hepatocytes by YAP-Hc. In Gunn rats transplanted with YAP-Hc+tamoxifen, there was a 65%-81% decline in serum bilirubin over 6 months versus 8%-20% with control-Hc, representing a 3-4-fold increase in therapeutic response. This correlated with liver repopulation as demonstrated by the presence of Ugt1a1-positive hepatocyte clusters in livers and western blot analysis of tissue homogenates. Conclusion: Tamoxifen-regulated nuclear translocation/function of hYAP-ERT2 enabled long-term repopulation of DPPIV-/- and Gunn rat livers by hYAP-ERT2-transduced hepatocytes without tumorigenesis. This cell transplantation strategy may offer a potential therapy for most of the inherited monogenic liver diseases that do not exhibit liver injury.

Cyclin-dependent kinase 4 is a preclinical target for diet-induced obesity.

When obesity is caused by consumption of a high-fat diet, the tumor suppressor pRb is phosphoinactivated in the neurons of the mediobasal hypothalamus, a brain area critical for energy-balance regulation. However, the functional relevance of pRb phosphoinactivation in the mediobasal hypothalamus to diet-induced obesity remains unknown. Here, we show that inhibiting pRb phosphorylation in the mediobasal hypothalamus can prevent and treat diet-induced obesity in mice. Expressing an unphosphorylable pRb nonselectively in the mediobasal hypothalamus or conditionally in anorexigenic POMC neurons inhibits diet-induced obesity. Intracerebroventricular delivery of US Food and Drug Administration-approved (FDA-approved) cyclin-dependent kinase 4 (CDK4) inhibitor abemaciclib inhibits pRb phosphorylation in the mediobasal hypothalamus and prevents diet-induced obesity. Oral administration of abemaciclib at doses approved for human use reduces fat mass in diet-induced obese mice by increasing lipid oxidation without significantly reducing lean mass. With analysis of recent literature identifying CDK4 as the most abundantly expressed neuronal CDK in the mediobasal hypothalamus, our work uncovers CDK4 as the major kinase for hypothalamic pRb phosphoinactivation and a highly effective central antiobesity target. As three CDK4/6 inhibitors have recently received FDA approval for life-long breast cancer therapy, our study provides a preclinical basis for their expedient repurposing for obesity management.