Loss Of Receptors Research Articles

Therapeutic Exploitation of Neuroendocrine Transdifferentiation Drivers in Prostate Cancer

Neuroendocrine prostate cancer (NEPC), an aggressive and lethal subtype of prostate cancer (PCa), often arises as a resistance mechanism in patients undergoing hormone therapy for prostate adenocarcinoma. NEPC is associated with a significantly poor prognosis and shorter overall survival compared to conventional prostate adenocarcinoma due to its aggressive nature and limited response to standard of care therapies. This transdifferentiation, or lineage reprogramming, to NEPC is characterised by the loss of androgen receptor (AR) and prostate-specific antigen (PSA) expression, and the upregulation of neuroendocrine (NE) biomarkers such as neuron-specific enolase (NSE), chromogranin-A (CHGA), synaptophysin (SYP), and neural cell adhesion molecule 1 (NCAM1/CD56), which are critical for NEPC diagnosis. The loss of AR expression culminates in resistance to standard of care PCa therapies, such as androgen-deprivation therapy (ADT) which target the AR signalling axis. This review explores the drivers of NE transdifferentiation. Key genetic alterations, including those in the tumour suppressor genes RB1, TP53, and PTEN, and changes in epigenetic regulators, particularly involving EZH2 and cell-fate-determining transcription factors (TFs) such as SOX2, play significant roles in promoting NE transdifferentiation and facilitate the lineage switch from prostate adenocarcinoma to NEPC. The recent identification of several other key novel drivers of NE transdifferentiation, including MYCN, ASCL1, BRN2, ONECUT2, and FOXA2, further elucidates the complex regulatory networks and pathways involved in this process. We suggest that, given the multifactorial nature of NEPC, novel therapeutic strategies that combine multiple modalities are essential to overcome therapeutic resistance and improve patient outcomes.

Exposure to an environmentally representative mixture of polybrominated diphenyl ethers (PBDEs) alters zebrafish neuromuscular development

Polybrominated diphenyl ethers (PBDEs) are a prevalent group of brominated flame retardants (BFRs) added to several products such as electronics, plastics, and textiles to reduce their flammability. They are reported as endocrine disruptors and neurodevelopmental toxicants that can accumulate in human and wildlife tissues, thus making their ability to leach out of products into the environment a great cause for concern. In this study, zebrafish (Danio rerio) embryos and larvae were exposed to a wide concentration range (1.5, 15, 150 and 300 pM) of a PBDE mixture from one to six days post-fertilization (dpf). Hatching rates, mortality and general morphology were assessed during the exposure period. A delay in hatching was observed at the two highest PBDEs concentrations and mortality rate increased at 6 dpf. By 4 dpf, larvae exposed to 150 pM and 300 pM PBDEs developed an upcurved phenotype. Analysis of motor behavior at 6 dpf revealed that PBDE exposure acutely reduced locomotion. To further analyze these motor deficits, we assessed the neural network density and motor neuron and neuromuscular junctions (NMJ) development by immunostaining and imaging. Acetylated α-tubulin staining revealed a significant loss of neurons in a dose-dependent manner. Synaptic vesicle protein 2 (SV2) and ⍺-bungarotoxin (⍺-BTX) staining revealed a similar pattern, with a significant loss of SV2 and nicotinic acetylcholine receptors, thus preventing the colocalization of presynaptic neurons with postsynaptic neurons. Consistent with these results, the presence of cleaved caspase-3 and acridine orange positive cells showed increased cell death in zebrafish larvae exposed to PBDEs. Our results suggest that exposure to PBDEs leads to deficits in the zebrafish neuromuscular system through neuron death, inducing morphological and motor deficiencies throughout their development. They provide valuable insight into the neurotoxic effects of PBDEs, further highlighting the relevance of the zebrafish model in toxicological studies.

Framework for the Pathology Workup of Metastatic Castration-Resistant Prostate Cancer Biopsies.

Lineage plasticity and histologic transformation from prostate adenocarcinoma to neuroendocrine prostate cancer (NEPC) occurs in up to 15-20% of patients with castration-resistant prostate cancer (CRPC) as mechanism of treatment resistance and is associated with aggressive disease and poor prognosis. NEPC tumors typically display small cell carcinoma morphology with loss of androgen receptor (AR) expression and gain of neuroendocrine (NE) lineage markers. However, there is a spectrum of phenotypes that are observed during the lineage plasticity process, and the clinical significance of mixed histologies or those that co-express AR and NE markers or lack all markers is not well defined. Translational research studies investigating NEPC have used variable definitions making clinical trial design challenging. Here we discuss the diagnostic workup of metastatic biopsies to help guide the reproducible classification of phenotypic CRPC subtypes. We recommend classifying CRPC tumors based on histomorphology (adenocarcinoma, small cell carcinoma, poorly differentiated carcinoma, other morphologic variant, or mixed morphology) and immunohistochemical markers with a priority for AR, NKX3.1, INSM1, synaptophysin and cell proliferation based on Ki-67 positivity, with additional markers to be considered based on the clinical context. Ultimately, a unified workup of metastatic CRPC biopsies can improve clinical trial design and eventually practice.

Expression of Cholinesterase in Bone Tumors, Blood and Cord Blood

The present study aimed to analyze Cholinesterase (CE) levels in cord blood from preeclamptic women and to evaluate cholinesterase status in patients with osteosarcoma. Serum cholinesterase levels were assessed in 30 cases of osteosarcoma and 30 controls suffering from musculoskeletal pain. Additionally, maternal and cord blood samples were collected from 25 women with preeclampsia and compared with those from 25 normotensive pregnant women and 25 normal, healthy controls. The results indicated that serum cholinesterase levels were significantly lower in osteosarcoma patients (Group I) compared to those with musculoskeletal pain (Group II, p < 0.05). Similarly, cholinesterase levels were reduced in the maternal blood of women with preeclampsia when compared to normotensive controls. Cord blood cholinesterase levels were lower in the infants of normotensive mothers, with levels reaching 88.65% of the maternal levels. Furthermore, cord blood cholinesterase levels were significantly lower in preeclamptic women compared to normotensive pregnant women. When comparing cholinesterase levels to those of normal controls, it was observed that CE levels were significantly elevated in both normotensive and preeclamptic women. The findings of low serum cholinesterase levels in this study suggest that cholinesterase secreted by osteoblasts is utilized in bone formation and tumorigenesis. Additionally, the decrease in cholinesterase levels associated with preeclampsia may be linked to the loss of muscarinic cholinergic receptors that occur in this condition.

PATH-08. MOLECULAR DIVERGENCE RATES DIFFER BETWEEN BRAIN METASTASES AND EXTRACRANIAL DISEASE SITES ACROSS PRIMARY TUMOR HISTOLOGIES

Abstract Genomic alterations and molecular subgroups between extracranial disease sites and brain metastases often differ, yet the prevalence and clinical significance of divergent evolution in brain metastases is not fully understood. This study examined genomic alterations and molecular subgroup divergence rates between matched brain metastases and extracranial disease sites. A retrospective, two-center study was conducted on patients who underwent resection of brain metastases between 2014-2022 with clinical and matched genomic data and/or molecular markers available. The overall cohort comprised 256 patients with matched tumors from multiple cancer types, most commonly from breast (n=108, 42.2%), melanoma (n=83, 32.4%), and NSCLC (n=43, 16.8%). Targeted next-generation sequencing of over 500 oncogenes was performed on resected tumors as part of clinical care (n=41 patients with matched specimens). Molecular subgroups for breast, melanoma, and non-small cell lung cancer were also assessed by immunohistochemistry to evaluate rates of molecular subgroup discordance between sites. Subgroup discordance by immunohistochemistry was observed most frequently across breast cancer (22.2%, n=24/108) with loss of the estrogen receptor (ER) and progesterone receptor (PR) and gain of HER2 most frequently observed within brain metastases. Molecular subgroup discordance was rare within melanoma (7.3%, n=6/82) and NSCLC (14.0%, n=6/43) patients. When evaluating oncogenomic alterations from targeted DNA sequencing in 41 patients with matched specimens, 80.5% (33/41) of brain metastases demonstrated a unique oncogene alteration profile compared to an extracranial disease site. Fourteen patients (34.1%) had a gain of at least 1 targetable alteration within a brain metastasis that was not observed in an extracranial disease site. Brain metastases demonstrated high rates of genomic divergence compared to primary and extracranial metastatic disease sites. This data supports obtaining brain metastasis tissue and conducting molecular profiling of this tissue to help select optimal CNS penetrant systemic therapies for each patient.

7448 Endogenous ACTH But Not Intermittent Cosyntropin Prevents Dexamethasone-Induced Adrenal Suppression In Mice

Abstract Disclosure: L.S. Gaston: None. H.R. Friedman: None. J.A. Majzoub: None. Background: Iatrogenic adrenal insufficiency (IAI) can persist for up to a year after withdrawal of long-term glucocorticoids (GC) by unknown mechanisms. We developed a mouse model of IAI in which 8 weeks of dexamethasone (DEX) induced protracted adrenocortical dysfunction despite early ACTH recovery. We then asked if 1) adrenal secretory dysfunction after GC withdrawal exceeded the cellular defect, and 2) ongoing trophic ACTH signaling while on DEX (either exogenous cosyntropin [COS] or endogenous ACTH) prevented IAI. Methods: Adult, male, wild-type C56BL/6J (n=3-6) mice were treated for 8 weeks (long-term) or 4-days (short-term) with DEX ± daily, intraperitoneal COS. At 1-2-week intervals after DEX±COS withdrawal, basal and stimulated ACTH and CORT were measured (mean±SEM) followed by necroscopy for morphometric analysis of immunostained, equatorial adrenal sections. Experiments were repeated in mice with irrepressible, endogenous ACTH due to selective loss of the hypothalamic GC receptor (Sim1-Cre:GR fl/fl, or SGR) and their Cre-negative (WT) littermates. Results: Stimulated corticosterone (CORT) required 8 weeks to normalize after stopping long-term DEX. Notably, both basal (811±220 vs. 216±24 pg/mL) and stimulated (1708±85 vs. 876±44) ACTH increased above controls by 1-week post-withdrawal (p<0.001 for both). Adrenal weights (1±0.1 vs. 2.5±0.1 mg) and cortical areas (480±9 vs. 1290±222 mm2) were significantly lower in DEX-treated glands vs. controls (p≤ 0.0001 for both) but recovered by 1-week post-withdrawal. Paucicellular, lipofuscin-rich accumulations were present in DEX-treated glands and persisted through 8 weeks post-withdrawal. In a linear regression of cortical area minus these inclusions (functional cortical area) vs. stimulated CORT (r2=0.43), predicted CORT was >2x higher (10 and 11 mg/dL) than measured CORT (5 for both) at 1- and 2-weeks post-DEX. In subsequent experiments, short-term COS inhibited DEX-induced adrenocortical apoptosis (200±85 vs 1170±481 TUNEL+ cells/HPF, p<0.01). However, CORT recovered more slowly in mice treated with long-term DEX+COS vs. DEX alone (doubling time=5.2 vs. 2.5 weeks), and glands were atrophic with lipofuscin-rich inclusions. Meanwhile, SGR mice maintained normal ACTH levels on long-term DEX. At the time of DEX withdrawal, SGR basal (14±4 vs.1.5±1.7 mcg/dL, p<0.05) and stimulated CORT responses (33±9.6 vs. 1.1±1.1, p<0.001), adrenal weights (2.3±0.2 vs. 1.1±0.06 mg, p≤ 0.001), and functional cortical area (1249±45 vs. 324±102 mm2, p≤ 0.001) were all greater than WT littermates, and lipofuscin-rich inclusions were absent in DEX-treated SGR glands. Conclusions: The adrenal is the major anatomic locus of post-withdrawal IAI in mice, which may involve early defects in both cortical size and secretory function. Novel therapies that mimic endogenous ACTH signaling during the period of GC exposure may prevent IAI. Presentation: 6/2/2024

Loss of C1q alters the auditory brainstem response.

Neural circuits in the auditory brainstem compute interaural time and intensity differences used to determine the locations of sound sources. These circuits display features that are specialized for these functions. The projection from the ventral cochlear nucleus (VCN) to the medial nucleus of the trapezoid (MNTB) body travels along highly myelinated fibers and terminates in the calyx of Held. This monoinnervating synapse emerges during development as multiple inputs are eliminated. We previously demonstrated that elimination of microglia with a colony stimulating factor-1 inhibitor results in impaired synaptic pruning so that multiple calyceal terminals reside on principal cells of MNTB. This inhibitor also resulted in impaired auditory brainstem responses (ABRs), with elevated thresholds and increased peak latencies. Loss of the microglial fractalkine receptor, CX3CR1, decreased peak latencies in the ABR. The mechanisms underlying these effects are not known. One prominent microglial signaling pathway involved in synaptic pruning and plasticity during development and aging is the C1q-initiated compliment cascade. Here we investigated the classical complement pathway initiator, C1q, in auditory brainstem maturation. We found that C1q expression is detected in the MNTB by the first postnatal week. C1q levels increased with age and were detected within microglia and surrounding the soma of MNTB principal neurons. Loss of C1q did not affect microglia-dependent calyceal pruning. Excitatory and inhibitory synaptic markers in the MNTB and LSO were not altered with C1q deletion. ABRs showed that C1q KO mice had normal hearing thresholds but shortened peak latencies. Altogether this study uncovers the developmental time frame of C1q expression in the sound localization pathway and shows a subtle functional consequence of C1q knockdown.

Microglial Melatonin Receptor 1 Degrades Pathological Alpha-Synuclein Through Activating LC3-Associated Phagocytosis InVitro.

Parkinson's disease (PD) is characterized by the formation of Lewy bodies (LBs), primarily constituted of α-synuclein (α-Syn). Microglial cells exhibit specific reactivity toward misfolded proteins such as α-Syn. However, the exact clearance mechanism and related molecular targets remain elusive. BV2 cells, primary microglia from wild-type and MT1 knockout mice, and primary cortical neurons were utilized as experimental models. The study investigated relevant mechanisms by modulating microglial MT1 expression through small RNA interference (RNAi) and lentiviral overexpression techniques. Furthermore, pathological aggregation of α-Syn was induced using pre-formed fibrils (PFF) α-Syn. Co-immunoprecipitation, immunofluorescence, Western blot (WB), and quantitative real-time PCR were used to elucidate the mechanisms of molecular regulation. In this study, we elucidated the regulatory role of the melatonin receptor 1 (MT1) in the microglial phagocytic process. Following MT1 knockout, the ability of microglial cells to engulf latex beads and zymosan particles decreased, subsequently affecting the phagocytic degradation of fibrillar α-Syn by microglial cells. Furthermore, the loss of MT1 receptors in microglial cells exacerbates the aggregation of α-Syn in neurons induced by pre-formed fibrils (PFF) α-Syn. Mechanistically, MT1 influences the phagocytic function of microglial cells by regulating the Rubicon-dependent LC3-associated phagocytosis (LAP) pathway. Taken together, the results suggest the neuroprotective function of microglial cells in clearing α-Syn through MT1-mediated LAP, highlighting the potential key role of MT1 in pathogenic mechanisms associated with α-Syn.

The 129 strain-derived passenger mutations in ACKR1-deficient mice alter the expression of PYHIN and Fc-gamma receptor genes.

A majority of genetically modified mice have been produced using 129 strain-derived embryonic stem cells (ESCs). Despite ample backcrosses with other strains, these may retain characteristic for 129 passenger mutations leading to confounding phenotypes unrelated to targeted genes. Here we show that widely used Ackr1-/-129ES mice have approximately 6Mb of the 129-derived genome retained adjacently to the Ackr1 locus on chromosome 1, including several characteristic polymorphisms. These most notably affect the expression of PYHIN and Fc-gamma receptor genes in myeloid cells resulting in the overproduction of IL-1β by activated macrophages and the loss of Fc-gamma receptors on myeloid progenitor cells. Therefore, caution is warranted when interpreting Ackr1-/-129ES mouse phenotypes as being solely due to the ACKR1 deficiency. Our findings call for a careful reevaluation of data from previous studies using Ackr1-/-129ES mice and underscore the limitations and pitfalls inherent to mouse models produced using traditional genetic engineering techniques involving 129 ESCs.

Abstract B054: Protease activity as a biomarker and potential target among pancreatic cancer patients

Abstract Background: The pancreas produces digestive proteases, which are often elevated in diseased states and capable of indiscriminate cell surface receptor cleavage. High levels of digestive protease activity have been implicated in the pathophysiology of pancreatic ductal adenocarcinoma (PDAC). We hypothesize that elevated digestive protease activity might downregulate or cleave immune cell receptors from the surface of cancer cells and contribute to the resistance of PDAC to immunotherapy. We have focused initially on major histocompatibility complex (MHC)-1, a ubiquitous receptor essential for antigen presentation, and CD155, an adhesion molecule over-expressed on cancer cells that regulates immune surveillance through binding to the TIGIT and CD226 receptors on leukocytes. Methods: The Rapid Assay for Protease Detection (RAPD) assay is a novel assay developed at our institution that utilizes fluorescent charge-changing peptide substrates to produce a positively charged fluorescent product fragment upon cleavage by the target protease. The RAPD assay was used to analyze protease activity levels in PDAC patients (N=50) and healthy (N=25) plasma samples. We also analyzed plasma samples obtained from an orthotopic KPC-derived mouse model for PDAC. We investigated the effects of specific proteases as well as plasma samples from PDAC and healthy subjects on MHC-1 and CD-155 receptor cleavage in cultured cells in vitro. Utilizing flow cytometry and immunofluorescent imaging, receptor loss was quantified for different proteases and plasma samples. Results: We observed elevated activity levels of digestive protease chymotrypsin as well as cathepsin-S and MMP-2 in the plasma of PDAC patients compared to healthy subjects. Similar patterns of protease activity were seen in plasma from tumor-bearing mice compared to non-tumor-bearing mice. Additionally, our results suggest loss of CD155 and MHC-1 from pancreatic cancer cells when incubated with trypsin and cathepsin-S. Incubation of cells with PDAC plasma also decreases the number of cells expressing MHC-1 and CD155 compared to control plasma, with greater differences observed in plasma with higher protease levels. Higher levels of cleaved CD155 are also detectable by ELISA in human and mouse PDAC plasma than in control plasma. Also, the protease activity (MMP2 and trypsin) correlates with plasma levels of CD155 and PD-L1. Conclusions: These studies begin to elucidate a possible role of digestive proteases in the ability of PDAC to evade the immune system. Ongoing experiments are exploring other immune receptors (including checkpoints) and whether specific protease inhibitors can block immune receptor cleavage. These experiments will inform subsequent experiments combining protease inhibitors with immunotherapy in mouse models. Citation Format: Utsav Joshi, Heather Farris, Jorge De La Torre De La Torre, kim Nguyen-Ta1, Michael Heller, Geert Schmid-Schonbein, Rebekah White. Protease activity as a biomarker and potential target among pancreatic cancer patients [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Advances in Pancreatic Cancer Research; 2024 Sep 15-18; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(17 Suppl_2):Abstract nr B054.

Nuclear lamin A/C phosphorylation by loss of androgen receptor leads to cancer-associated fibroblast activation

Alterations in nuclear structure and function are hallmarks of cancer cells. Little is known about these changes in Cancer-Associated Fibroblasts (CAFs), crucial components of the tumor microenvironment. Loss of the androgen receptor (AR) in human dermal fibroblasts (HDFs), which triggers early steps of CAF activation, leads to nuclear membrane changes and micronuclei formation, independent of cellular senescence. Similar changes occur in established CAFs and are reversed by restoring AR activity. AR associates with nuclear lamin A/C, and its loss causes lamin A/C nucleoplasmic redistribution. AR serves as a bridge between lamin A/C and the protein phosphatase PPP1. Loss of AR decreases lamin-PPP1 association and increases lamin A/C phosphorylation at Ser 301, a characteristic of CAFs. Phosphorylated lamin A/C at Ser 301 binds to the regulatory region of CAF effector genes of the myofibroblast subtype. Expression of a lamin A/C Ser301 phosphomimetic mutant alone can transform normal fibroblasts into tumor-promoting CAFs.

Receptors and Host Factors for Enterovirus Infection: Implications for Cancer Therapy.

Enteroviruses, with their diverse clinical manifestations ranging from mild or asymptomatic infections to severe diseases such as poliomyelitis and viral myocarditis, present a public health threat. However, they can also be used as oncolytic agents. This review shows the intricate relationship between enteroviruses and host cell factors. Enteroviruses utilize specific receptors and coreceptors for cell entry that are critical for infection and subsequent viral replication. These receptors, many of which are glycoproteins, facilitate virus binding, capsid destabilization, and internalization into cells, and their expression defines virus tropism towards various types of cells. Since enteroviruses can exploit different receptors, they have high oncolytic potential for personalized cancer therapy, as exemplified by the antitumor activity of certain enterovirus strains including the bioselected non-pathogenic Echovirus type 7/Rigvir, approved for melanoma treatment. Dissecting the roles of individual receptors in the entry of enteroviruses can provide valuable insights into their potential in cancer therapy. This review discusses the application of gene-targeting techniques such as CRISPR/Cas9 technology to investigate the impact of the loss of a particular receptor on the attachment of the virus and its subsequent internalization. It also summarizes the data on their expression in various types of cancer. By understanding how enteroviruses interact with specific cellular receptors, researchers can develop more effective regimens of treatment, offering hope for more targeted and efficient therapeutic strategies.

The third symposium on treatment-induced neuroendocrine prostate cancer: insights and future directions.

Neuroendocrine prostate cancer (NEPC) is a rare and aggressive subtype of prostate cancer (PCa), emerging from advanced treatments and characterized by loss of androgen receptor (AR) signaling and neuroendocrine features, leading to rapid progression and treatment resistance. The third symposium on treatment-induced NEPC, held from 21 to23 June2024, at Harrison Hot Springs Resort, BC, Canada, united leading global researchers and clinicians. Sponsored by the Vancouver Prostate Centre (VPC), Canadian Institute of Health Research, Prostate Cancer Foundation Canadaand Pharma Planter Inc, the event focused on the latest NEPC research and innovative treatment strategies. Co-chaired by Drs. Yuzhuo Wang and Martin Gleave, the symposium featured sessions on NEPC's historical context, molecular pathways, epigenetic regulationand the role of the tumor microenvironment and metabolism in its progression. Keynotes from experts like Dr. Himisha Beltran and Dr. Martin Gleave highlighted the complexity of NEPC. The Emerging Talent session showcased new research, pointing to the future of NEPC treatment. The symposium concluded with a consensus on the need for early detection, targeted therapiesand personalized medicine to effectively combat NEPC, emphasizing the importance of global collaboration in advancing NEPC understanding and treatment.

The histone methyltransferase Mixed-lineage-leukemia-1 drives T cell phenotype via Notch signaling in diabetic tissue repair.

Immune cell-mediated inflammation is important in normal tissue regeneration but can be pathologic in diabetic wounds. Limited literature exists on the role of CD4+ T cells in normal or diabetic wound repair; however, the imbalance of CD4+ Th17/Tregs has been found to promote inflammation in other diabetic tissues. Here, using human tissue and murine transgenic models, we identified that the histone methyltransferase Mixed-lineage-leukemia-1 (MLL1) directly regulates the Th17 transcription factor RORγ via an H3K4me3 mechanism and increases expression of Notch receptors and downstream Notch signaling. Furthermore, we found that Notch receptor signaling regulates CD4+ Th cell differentiation and is critical for normal wound repair, and loss of upstream Notch pathway mediators or receptors in CD4+ T cells resulted in the loss of CD4+ Th cell differentiation in wounds. In diabetes, MLL1 and Notch-receptor signaling was upregulated in wound CD4+ Th cells, driving CD4+ T cells toward the Th17 cell phenotype. Treatment of diabetic wound CD4+ T cells with a small molecule inhibitor of MLL1 (MI-2) yielded a significant reduction in CD4+ Th17 cells and IL-17A. This is the first study to our knowledge to identify the MLL1-mediated mechanisms responsible for regulating the Th17/Treg balance in normal and diabetic wounds and to define the complex role of Notch signaling in CD4+ T cells in wounds, where increased or decreased Notch signaling both result in pathologic wound repair. Therapeutic targeting of MLL1 in diabetic CD4+ Th cells may decrease pathologic inflammation through regulation of CD4+ T cell differentiation.

Ngfr+ cholinergic projection from SI/nBM to mPFC selectively regulates temporal order recognition memory

Acetylcholine regulates various cognitive functions through broad cholinergic innervation. However, specific cholinergic subpopulations, circuits and molecular mechanisms underlying recognition memory remain largely unknown. Here we show that Ngfr+ cholinergic neurons in the substantia innominate (SI)/nucleus basalis of Meynert (nBM)-medial prefrontal cortex (mPFC) circuit selectively underlies recency judgements. Loss of nerve growth factor receptor (Ngfr−/− mice) reduced the excitability of cholinergic neurons in the SI/nBM-mPFC circuit but not in the medial septum (MS)-hippocampus pathway, and impaired temporal order memory but not novel object and object location recognition. Expression of Ngfr in Ngfr−/− SI/nBM restored defected temporal order memory. Fiber photometry revealed that acetylcholine release in mPFC not only predicted object encounters but also mediated recency judgments of objects, and such acetylcholine release was absent in Ngfr−/− mPFC. Chemogenetic and optogenetic inhibition of SI/nBM projection to mPFC in ChAT-Cre mice diminished mPFC acetylcholine release and deteriorated temporal order recognition. Impaired cholinergic activity led to a depolarizing shift of GABAergic inputs to mPFC pyramidal neurons, due to disturbed KCC2-mediated chloride gradients. Finally, potentiation of acetylcholine signaling upregulated KCC2 levels, restored GABAergic driving force and rescued temporal order recognition deficits in Ngfr−/− mice. Thus, NGFR-dependent SI/nBM-mPFC cholinergic circuit underlies temporal order recognition memory.

Estrogen Regulated Genes Compel Apoptosis in Breast Cancer Cells, Whilst Stimulate Antitumor Activity in Peritumoral Immune Cells in a Janus-Faced Manner.

Background: Breast cancer incidence and mortality exhibit a rising trend globally among both premenopausal and postmenopausal women, suggesting that there are serious errors in our preventive and therapeutic measures. Purpose: Providing a series of valuable, but misunderstood inventions highlighting the role of increasing estrogen signaling in prevention and therapy of breast cancer instead of its inhibition. Results: 1. Breast cells and breast cancer cells with germline BRCA1/2 mutations similarly show defects in liganded estrogen receptor (ER) signaling, demonstrating its role in genomic instability and cancer initiation. 2. In breast tumors, the increased expression of special receptor family maybe an effort for self-directed improvement of genomic defects, while the weakness or loss of receptors indicates a defect requiring medical repair. 3. ER overexpression in breast cancer cells is capable of strengthening estrogen signaling and DNA repair, while in ER negative tumors, HER2 overexpression tries to upregulate unliganded ER activation and genome stabilization. 4. ER-positive breast cancers responsive to endocrine therapy may show a compensatory ER overexpression resulting in a transient tumor response. Breast cancers non-responsive to antiestrogen treatment exhibit HER2-overexpression for compensating the complete inhibition of hormonal ER activation. 5. In breast tumors, somatic mutations serve upregulation of ER activation via liganded or unliganded pathway helping genome stabilization and apoptotic death. 6. The mutual communication between breast cancer and its inflammatory environment is a wonderful partnership among cells fighting for genome stabilization and apoptotic death of tumor. 7. In breast cancers, there is no resistance to genotoxic or immune blocker therapies, but rather, the nonresponsive tumor cells exhaust all compensatory possibilities against therapeutic damages. Conclusions: Understanding the behavior and ambition of breast cancer cells may achieve a turn in therapy via applying supportive care instead of genotoxic measures.

Assessments of prostate cancer cell functions highlight differences between a pan-PI3K/mTOR inhibitor, gedatolisib, and single-node inhibitors of the PI3K/AKT/mTOR pathway.

Metastatic castration-resistant prostate cancer (mCRPC) is characterized by loss of androgen receptor (AR) sensitivity and oncogenic activation of the PI3K/AKT/mTOR (PAM) pathway. Loss of the PI3K regulator PTEN is frequent during prostate cancer (PC) initiation, progression, and therapeutic resistance. Co-targeting the PAM/AR pathways is a promising mCRPC treatment strategy but is hampered by reciprocal negative feedback inhibition or feedback relief. Most PAM inhibitors selectively spare (or weakly inhibit) one or more key nodes of the PAM pathway, potentiating drug resistance depending on the PAM pathway mutation status of patients. We posited that gedatolisib, a uniformly potent inhibitor of all class I PI3K isoforms, as well as mTORC1 and mTORC2, would be more effective than inhibitors targeting single PAM pathway nodes in PC cells. Using a combination of functional and metabolic assays, we evaluated a panel of PC cell lines with different PTEN/PIK3CA status for their sensitivity to multi-node PAM inhibitors (PI3K/mTOR: gedatolisib, samotolisib) and single-node PAM inhibitors (PI3Kα: alpelisib; AKT: capivasertib; mTOR: everolimus). Gedatolisib induced anti-proliferative and cytotoxic effects with greater potency and efficacy relative to the other PAM inhibitors, independent of PTEN/PIK3CA status. The superior effects of gedatolisib were likely associated with more effective inhibition of critical PAM-controlled cell functions, including cell cycle, survival, protein synthesis, oxygen consumption rate, and glycolysis. Our results indicate that potent and simultaneous blockade of all class I PI3K isoforms, mTORC1, and mTORC2 could circumvent PTEN-dependent resistance. Gedatolisib, as a single agent and in combination with other therapies, reported promising preliminary efficacy and safety in various solid tumor types. Gedatolisib is currently being evaluated in a Phase 1/2 clinical trial in combination with darolutamide in patients with mCRPC previously treated with an AR inhibitor, and in a Phase 3 clinical trial in combination with palbociclib and fulvestrant in patients with HR+/HER2- advanced breast cancer.

Loss of Smooth Muscle Tenascin-X Inhibits Vascular Remodeling Through Increased TGF-β Signaling.

Vascular smooth muscle cells (VSMCs) are highly plastic. Vessel injury induces a phenotypic transformation from differentiated to dedifferentiated VSMCs, which involves reduced expression of contractile proteins and increased production of extracellular matrix and inflammatory cytokines. This transition plays an important role in several cardiovascular diseases such as atherosclerosis, hypertension, and aortic aneurysm. TGF-β (transforming growth factor-β) is critical for VSMC differentiation and to counterbalance the effect of dedifferentiating factors. However, the mechanisms controlling TGF-β activity and VSMC phenotypic regulation under in vivo conditions are poorly understood. The extracellular matrix protein TN-X (tenascin-X) has recently been shown to bind TGF-β and to prevent it from activating its receptor. We studied the role of TN-X in VSMCs in various murine disease models using tamoxifen-inducible SMC-specific knockout and adeno-associated virus-mediated knockdown. In hypertensive and high-fat diet-fed mice, after carotid artery ligation as well as in human aneurysmal aortae, expression of Tnxb, the gene encoding TN-X, was increased in VSMCs. Mice with smooth muscle cell-specific loss of TN-X (SMC-Tnxb-KO) showed increased TGF-β signaling in VSMCs, as well as upregulated expression of VSMC differentiation marker genes during vascular remodeling compared with controls. SMC-specific TN-X deficiency decreased neointima formation after carotid artery ligation and reduced vessel wall thickening during Ang II (angiotensin II)-induced hypertension. SMC-Tnxb-KO mice lacking ApoE showed reduced atherosclerosis and Ang II-induced aneurysm formation under high-fat diet. Adeno-associated virus-mediated SMC-specific expression of short hairpin RNA against Tnxb showed similar beneficial effects. Treatment with an anti-TGF-β antibody or additional SMC-specific loss of the TGF-β receptor reverted the effects of SMC-specific TN-X deficiency. In summary, TN-X critically regulates VSMC plasticity during vascular injury by inhibiting TGF-β signaling. Our data indicate that inhibition of vascular smooth muscle TN-X may represent a strategy to prevent and treat pathological vascular remodeling.

High-grade Anaplastic Transformation of Ovarian Serous Borderline Tumor: A Distinctive Morphology With Abundant Dense Eosinophilic Cytoplasm and Dismal Prognosis.

Ovarian serous borderline tumors (SBTs) have a generally favorable prognosis. Although the risk of progression to low-grade serous carcinoma is well documented, progression to high-grade carcinoma is rare. We report the clinicopathologic features of seven SBTs, each associated with the presence of a morphologically unique high-grade component with an extremely dismal prognosis. All of the SBTs exhibited typical hierarchical branching and scattered eosinophilic cells, whereas the high-grade component consisted of a profuse proliferation of epithelioid cells with abundant dense, eosinophilic cytoplasm, variable nuclear pleomorphism, and evident loss of WT1, estrogen receptor, and p16 positivity. In most cases, the SBT demonstrated an abrupt transition to the high-grade component, but one patient initially presented with the usual SBT and developed a recurrent disease that was composed entirely of the high-grade component. Targeted next-generation sequencing revealed identical driver mutations in both the SBT and high-grade components ( BRAF in 3, KRAS in 1), confirming clonality. Three cases, in addition, harbored telomerase reverse transcriptase promoter mutations in both components. One case, despite insufficient material for sequencing, was BRAF V600E-positive by immunohistochemistry. Most patients with available follow-up data died within 9 months of diagnosis. This study confirms prior reports of ovarian SBT transformation to high-grade carcinoma and further characterizes a distinct subset with abundant dense eosinophilic cytoplasm and an extremely dismal prognosis. The presence of BRAF mutations in a major subset of these tumors questions the notion that BRAF is associated with senescent eosinophilic cells and improved outcomes in SBT. The role of the additional telomerase reverse transcriptase promoter mutations merits further investigation.

Loss of the systemic vitamin A transporter RBPR2 affects the quantitative balance between chromophore and opsins in visual pigment synthesis.

The distribution of dietary vitamin A/all-trans retinol (ROL) throughout the body is critical for maintaining retinoid function in peripheral tissues and for generating visual pigments for photoreceptor cell function. ROL circulates in the blood bound to the retinol binding protein 4 (RBP4) as RBP4-ROL. Two membrane receptors, RBPR2 in the liver and STRA6 in the eye are proposed to bind circulatory RBP4 and this mechanism is critical for internalizing ROL into cells. Here, we present a longitudinal investigation towards the importance of RBPR2 and influence of the diet on systemic retinoid homeostasis for visual function. Age matched Rbpr2-KO (Rbpr2 -/- ) and wild-type (WT) mice were fed either a vitamin A sufficient (VAS) or a vitamin A deficient (VAD) diet. At 3- and 6-months, we performed retinoid quantification of ocular and non-ocular tissues using HPLC analysis and complemented the data with visual physiology, rhodopsin quantification by spectrophotometry, and biochemical analysis. At 3-months and compared to WT mice, Rbpr2 -/- mice fed either vitamin A diets displayed lower scotopic and photopic electroretinogram (ERG) responses, which correlated with HPLC analysis that revealed Rbpr2 -/- mice had significantly lower hepatic and ocular retinoid content. Interestingly, with the exception of the liver, long-term feeding of Rbpr2 -/- mice with a VAS diet promoted all-trans retinol accumulation in most peripheral tissues. However, even under VAS dietary conditions significant amounts of unliganded opsins in rods, together with decreased visual responses were evident in aged mice lacking RBPR2, when compared to WT mice. Together, our analyses characterize the molecular events underlying nutritional blindness in a novel mouse model and indicate that loss of the liver specific RBP4-ROL receptor, RBPR2, influences systemic retinoid homeostasis and rhodopsin synthesis, which causes profound visual function defects under severe vitamin A deficiency conditions.