Sensitivity Of Cells Research Articles

Vesicle-Transported Multidrug Resistance as a Possible Therapeutic Target of Natural Compounds

Background/Objectives: A key role of extracellular vesicles (EVs) is mediating both cell–cell and cell–stroma communication in pathological/physiological conditions. EVs from resistant tumor cells can transport different molecules like P-glycoprotein (P-gp), acting as a shuttle between donor and recipient cells, resulting in a phenotypic change. The aim of our work was to isolate, characterize, and inhibit the release of EVs in two multidrug resistance (MDR) cancer models: MCF-7R (breast cancer cell line) and HL-60R (acute myeloid leukemia cell line). Methods: The existence of P-gp in EVs from MDR cells was confirmed by Western blotting assays. The characterization of EVs was carried out by evaluating the size using NTA and the presence of specific markers such as CD63, Hsp70 and Syntenin. The ability of HL-60R and MCF-7R to perform horizontal transfer of P-gp via EVs to sensitive cells was assessed using three different methods. The acquisition of resistance and its inhibition in recipient cells was confirmed by MTS 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Results: Our data showed that cell lines (MDR) release P-gp-loaded EVs, unlike sensitive cells. The acquisition of resistance determined by the incorporation of P-gp into the membrane of sensitive cells was confirmed by the reduced cytotoxic activity of doxorubicin. Natural compounds such as curcumin, lupeol, and heptacosane can block vesicular transfer and restore the sensitivity of HL-60 and MCF-7 cells. Conclusions: Our study demonstrates that natural inhibitors able to reverse this mechanism may represent a new therapeutic strategy to limit the propagation of the resistant phenotype.

Study of TRAIL and SAHA Co-Treatment on Leukemia K562 Cell Line.

TRAIL (Tumor Necrosis Factor-Related Apoptosis-Inducing Ligand) is an attractive agent being considered a potential cancer treatment. It attaches to its death receptors, leading many cancer cells to apoptosis. However, some malignancies indicate substantial resistance to TRAIL, challenging anticancer scientists. Herein, combination therapy with TRAIL plus SAHA (Suberoyl Anilide Hydroxamic Acid) was conducted to evaluate the capability of SAHA to overcome TRAIL resistance in the leukemia K562 cell line. First, the IC50 for SAHA was calculated (2 µM) at 12, 24, 48, and 72 h of treatment using MTT assay. Second, the K562 cells were treated with concentrations of 50 and 100 nM of TRAIL and 2 μM of SAHA separately and together for 24, 48, and 72 h and the survival of these cells was evaluated by Flowcytometry following the annexin-V and PI staining. To demonstrate the non-toxicity of the combined treatment for normal cells, the HEK-293 cell line was treated with the TRAIL 100 nM and SAHA 2 μM combined and separated at the same periods. In the end, by performing real-time PCR, the amount of candidate genes' expression implicated in TRAIL resistance, and the levels of BCR-ABL expression was measured. The drug dosages were not toxic to normal cells. SAHA plus TRAIL strongly triggered apoptosis in K562 cells after 24, 48, and 72 h of exposure. Furthermore, it was shown that DR4, DR5, and CHOP expressions were enhanced, and PI3K, Akt, ERK, STAT3, c-FLIPL, NF-κB, and BCR-ABL expressions were decreased by SAHA in K562 cells. Our study indicated that SAHA combined with TRAIL can increase the sensitivity of K562 leukemic cells to TRAIL by suppressing intracellular anti-apoptotic molecules and augmenting the expressions of DR4/DR5 and CHOP.

Endogenous Magnetic Lipid Droplet-Mediated Cascade-Targeted Sonodynamic Therapy as an Approach to Reversing Breast Cancer Multidrug Resistance.

Multidrug resistance (MDR) has emerged as a major barrier to effective breast cancer treatment, contributing to high rates of chemotherapy failure and disease recurrence. There is thus a pressing need to overcome MDR and to facilitate the efficient and precise treatment of breast cancer in a targeted manner. In this study, endogenous functional lipid droplets (IR780@LDs-Fe3O4/OA) were developed and used to effectively overcome the limited diffusion distance of reactive oxygen species owing to their amenability to cascade-targeted delivery, thereby facilitating precise and effective sonodynamic therapy (SDT) for MDR breast cancer. Initially, IR780@LDs-Fe3O4/OA was efficiently enriched within tumor sites in a static magnetic field, achieving the visualization of tumor treatment. Subsequently, the cascade-targeted SDT combined with the Fenton effect induced lysosome membrane permeabilization and relieved lysosomal sequestration, thus elevating drug concentration at the target site. This treatment approach also suppressed ATP production, thereby inhibiting P-glycoprotein-mediated chemotherapeutic drug efflux. This cascade-targeted SDT strategy significantly increased the sensitivity of MDR cells to doxorubicin, increasing the IC50 value of doxorubicin by approximately 10-fold. Moreover, the cascade-targeted SDT also altered the gene expression profiles of MDR cells and suppressed the expression of MDR-related genes. In light of these promising results, the combination of cascade-targeted SDT and conventional chemotherapy holds great clinical promise as an effective treatment modality with excellent biocompatibility that can improve MDR breast cancer patient outcomes.

DNA methylation-driven gene FAM3D promotes colorectal cancer growth via the ATF4-SESN2-mTORC1 pathway.

Globally, colorectal cancer (CRC) is the malignant tumor with the highest mortality rate after lung cancer. Abnormal DNA methylation drives dysregulated gene expression, thereby promoting CRC progression and leading to poor prognosis. We identified a 3-CpG methylation signature that is independently associated with CRC prognosis. The model consists of three methylation-driven genes: FAM3 Metabolism Regulating Signaling Molecule D (FAM3D), DAPP1, and PIGR. However, the prognostic significance, biological function, and related mechanisms of the individual methylation-driven gene FAM3D in CRC have not been studied. Here, we discovered that FAM3D expression was reduced in CRC tissues and cells, and that high methylation and low expression of FAM3D were independent prognostic risk factors for CRC. In addition, FAM3D promoted the growth and movement of CRC cells in vitro and the proliferation in nude mice, mainly by inhibiting ATF4 transcription and downregulating SESN2 expression, and ultimately activating mTORC1. Furthermore, FAM3D resulted in reduced sensitivity of CRC cells to oxaliplatin, cisplatin, and 5-fluorouracil. Our study showed that FAM3D activates the mTORC1 pathway through the ATF4-SESN2 axis and promotes the malignant progression of CRC, which contributes to predict CRC prognosis and guide individualized treatment.

Cyclin C promotes development and progression of B-cell acute lymphoblastic leukemia by counteracting p53-mediated stress responses.

Despite major therapeutic advances in the treatment of acute lymphoblastic leukemia (ALL), resistances and long-term toxicities still pose significant challenges. Cyclins and their associated cyclin-dependent kinases are one focus of cancer research when looking for targeted therapies. We discovered cyclin C as a key factor for B-ALL development and maintenance. While cyclin C is non-essential for normal hematopoiesis, CcncΔ/Δ BCR::ABL1+ B-ALL cells fail to elicit leukemia in mice. RNA sequencing experiments revealed a p53 pathway deregulation in CcncΔ/Δ BCR::ABL1+ cells resulting in the incapability of the leukemic cells to adequately respond to stress. A genome-wide CRISPR/Cas9 loss-of-function screen supplemented with additional knock-outs unveiled a dependency of human B-lymphoid cell lines on CCNC. High cyclin C levels in B-cell precursor (BCP) ALL patients were associated with poor event-free survival and increased risk of early disease recurrence after remission. Our findings highlight cyclin C as potential therapeutic target for B-ALL, particularly to enhance cancer cell sensitivity to stress and chemotherapy.

Machine Learning-Aided 3D Dynamic SERS Strategy for Physiological Mapping: Biotoxicity of Environmentally Dimensional Aged Nanoplastics and Corresponding Protein Corona Complexes.

Nanoplastics (NPs) are emerging pollutants that undergo inevitable aging in the environment, raising concerns about human exposure and health hazards. Research on the cytotoxicity of various polymer types of NPs, aged nanoplastics (aNPs), and their interactions with proteins (aNPs-protein corona) is still nascent. Traditional cytotoxicity detection methods often rely on end point assays with restricted temporal resolution and analysis of single or multiple biomarkers. Here, we propose a novel approach integrating the 3D dynamic SERS strategy (DSS) with machine learning to rapidly analyze the cell fate and death modes induced by NPs, aNPs, and aNPs-protein corona complexes at the molecular level. PS, PVC, PMMA, and PC products from the water environment were used to prepare the corresponding NPs, and the impact of UV irradiation on their physicochemical properties was examined. DSS systematically maps the molecular changes in the cellular secretome caused by these NPs. Machine learning effectively extracts information from complex spectra, differentiating between biological samples. Results show prolonged UV exposure increases cell sensitivity to ferroptosis and cytotoxicity in various aNPs, while the protein corona on aNPs significantly mitigates toxicity associated with surface oxygen-containing functional groups, resulting in a reduced similarity to ferroptosis signatures. 3D DSS with machine learning technique analyzes the overall metabolite profile at the molecular level rather than individual biomarkers. This study is the first attempt to compare the biotoxicity of diverse polymer NPs, aNPs, and aNPs-protein coronas at cellular and molecular levels in human hepatocytes, enhancing our understanding of the complex biological impacts of NPs.

The DHODH inhibitor teriflunomide impedes cell proliferation and enhances chemosensitivity to daunorubicin (DNR) in T-cell acute lymphoblastic leukemia.

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological tumor that requires novel treatment strategies, especially for relapsed/refractory cases. Dihydroorotate dehydrogenase (DHODH), a key enzyme in the de novo pyrimidine synthesis pathway, has been identified as a potential target for tumors. Besides, Teriflunomide (TRF) is a DHODH inhibitor with anticancer effects; however, its role in T-ALL remains poorly understood. Here, we investigated the potential anticancer effects of TRF on T-ALL cells, and the results showed that TRF inhibited cell proliferation, caused S-phase cell cycle arrest, and promoted apoptosis of T-ALL (MOLT4 and JURKAT) cell lines. In addition, TRF reduced the infiltration capacity of T-ALL cells in T-ALL xenograft mice while up-regulating the expression of P53 and BTG2. The BTG2 knockdown significantly attenuated the inhibitory effect of TRF on cellular growth and suppressed the TRF-mediated elevated expression of P53 in T-ALL cells. Moreover, combined treatment with TRF and daunorubicin (DNR) significantly reduced cell viability and promoted apoptosis in DNR-resistant T-ALL cells. Our study provides valuable insights into the critical role of TRF in treating T-ALL while increasing the sensitivity of DNR-resistant T-ALL cells to DNR.

The Impact of Spliceosome Inhibition in SF3B1-Mutated Uveal Melanoma.

Unfortunately, treatment of patients with uveal melanoma (UM) with metastatic disease is limited. Twenty percent of patients with UM harbor a mutation in the splicing factor gene SF3B1, suggesting that aberrant spliceosome function plays a vital role in tumorigenesis. Splicing inhibitors exploit the preferential sensitivity of spliceosome-compromised leukemic cells to these compounds. We studied the effect of the splicing inhibitor E7107 using two UM cell lines and ex vivo cultured SF3B1- and BAP1-mutated primary UM tumor slices. These UM cell lines and ex vivo tumor slices were exposed for 24 hours to different concentrations of E7107. Tumor slices were stained with hematoxylin and eosin (H&E) and incubated with BAP1, MelanA, MIB-1, and caspase-3 antisera. The E7107-exposed UM cell lines exhibited decreased cell viability and increased apoptosis, with the greatest effect on SF3B1-mutated UM cells. A similar effect on UM tumor slices was observed upon exposure to E7107. Additionally, RNA was isolated for differential isoform expression analysis. No significant difference in isoform usage was found genome-wide. However, specific genes were differentially expressed after E7107 treatment in the SF3B1-mutated samples. Moreover, E7107 had the greatest effect on intron retention. This study indicates/suggests that mutated SF3B1 UM cells are more sensitive to the splicing inhibitor E7107 than wild-type SF3B1 UM cells.

Expression of Concern: HER2 decreases drug sensitivity of ovarian cancer cells via inducing stem cell-like property in a NFκB-dependent way.

Expression of Concern: HER2 decreases drug sensitivity of ovarian cancer cells via inducing stem cell-like property in a NFκB-dependent way.

Compensatory activity of the PC-ME1 metabolic axis underlies differential sensitivity to mitochondrial complex I inhibition.

Deficiencies in the electron transport chain (ETC) lead to mitochondrial diseases. While mutations are distributed across the organism, cell and tissue sensitivity to ETC disruption varies, and the molecular mechanisms underlying this variability remain poorly understood. Here we show that, upon ETC inhibition, a non-canonical tricarboxylic acid (TCA) cycle upregulates to maintain malate levels and concomitant production of NADPH. Our findings indicate that the adverse effects observed upon CI inhibition primarily stem from reduced NADPH levels, rather than ATP depletion. Furthermore, we find that Pyruvate carboxylase (PC) and ME1, the key mediators orchestrating this metabolic reprogramming, are selectively expressed in astrocytes compared to neurons and underlie their differential sensitivity to ETC inhibition. Augmenting ME1 levels in the brain alleviates neuroinflammation and corrects motor function and coordination in a preclinical mouse model of CI deficiency. These studies may explain why different brain cells vary in their sensitivity to ETC inhibition, which could impact mitochondrial disease management.

Targeting oncogenic MAGEA6 sensitizes triple negative breast cancer to doxorubicin through its autophagy and ferroptosis by stabling AMPKα1

Melanoma-associated antigen A6 (MAGEA6) is well known to have oncogenic activity, but the underlying mechanisms by which it regulates tumor progression and chemo-resistance, especially in triple-negative breast cancer (TNBC), have been unknown. In the study, the differential expression genes (DEGs) in TNBC tumor tissues and TNBC-resistant tumor tissues were analyzed based on TCGA and GEO datasets. MAGEA6, as the most significantly expressed gene, was analyzed by RT-qPCR, western blotting and immunohistochemistry assay in TNBC cell lines and tumor tissues. The potential mechanisms that influence chemo-resistance were also evaluated. Results displayed that MAGEA6 was highly expressed in TNBC and involved in drug resistance. MAGEA6 silencing enhanced the chemo-sensitivity of TNBC to doxorubicin (DOX) in vitro and in vivo, as determined by decreasing IC50 value, proliferation and invasion capacity, and triggering apoptosis. Mechanistically, it was shown that MAGEA6 depletion sensitized TNBC to DOX via regulating autophagy. Ubiquitination assay displayed that knockdown of MAGEA6 decreased the AMPKα1 ubiquitination, thereby elevating the levels of AMPKα1 and p-AMPKα in TNBC cells. Importantly, AMPK inhibitor (Compound C) can reduce the LC3II/I level induced by sh-MAGEA6, indicating that sh-MAGEA6 activated AMPK signaling through suppressing AMPKα1 ubiquitination and then facilitated autophagy in TNBC. Furthermore, we also observed that AMPK is required for SLC7A11 to regulate ferroptosis, and supported the crux roles of MAGEA6/AMPK/SLC7A11-mediated ferroptosis on modulating DOX sensitivity in TNBC cells. These findings indicated that targeting MAGEA6 can enhance the chemo-sensitivity in TNBC via activation of autophagy and ferroptosis; its mechanism involves AMPKα1-dependent autophagy and AMPKα1/SLC7A11-induced ferroptosis.

8038 Targeting Breast Cancer Stem Cells With Oncolytic Mammalian Orthoreovirus (MRV)

Abstract Disclosure: N.I. Roman Ortiz: None. J. Davydova: None. P. Danthi: None. J.H. Ostrander: None. Breast cancer is the most frequently diagnosed malignant cancer in women and is the second leading cause of cancer deaths among women in the United States. Patients with ER+ breast cancer can experience recurrence for more than 10 years after initial diagnosis. Breast cancer stem-like cells (BCSC) are slowly proliferative and exist as a minority sub-population (0-5%) within the tumor. Existing treatments target rapidly dividing cells, and BCSC are unresponsive to these therapies. Due to their self-renewal capabilities, BCSCs can fuel recurrence, metastasis, and resistance to therapies. Notably, no FDA-approved therapeutics selectively target BCSCs. Mammalian orthoreovirus (MRV) is an oncolytic virus tested in clinical trials for many cancer types including metastatic breast cancer. MRV was deemed safe but lacked efficacy as standalone treatment. We tested various laboratory MRV strains (T1L, R2) with T3D, a similar strain to the one evaluated in clinical trials. Our studies suggest that T3D is less effective in killing ER+ breast cancer cells and BCSCs compared to T1L and R2. To understand how T1L and R2 are more effective at killing ER+ breast cancer we aim to test the stages of MRV infection and how MRV induces cell death in ER+ therapy sensitive and resistant cells. MRV can enter cells by receptor mediated endocytosis through attachment with Junctional Adhesion Molecule A (JAM-A) and sialic acids as co-receptors. We have found that T1L attaches to cells in a JAM-A-dependent manner in ER+ sensitive cancer cells, while ER+ therapy resistant cells have increased resistance to JAM-A mediated endocytosis. Previous work has shown that apoptosis is involved in MRV-induced cell death. We found that apoptosis inhibitors in MRV-treated cells increase cell viability, suggesting that MRV-induces apoptotic cell death in ER+ breast cancer cells. Our current studies involve using RNA sequencing as a tool to assess gene expression of ER+ therapy sensitive and resistant cells infected with MRV at early and late stages of infection to determine key genes and pathways associated with cell death.We also aim to generate novel MRV strains with enhanced BCSC killing. We used a forward genetic approach and serially passaged MRV strains in BCSC enriched tumorsphere cultures of MCF-7 paclitaxel resistant (TaxR) cells to generate a selective oncolytic virus that can infect and kill BCSCs. Preliminary data has shown that serially passaged (SP) MRV strains (T1L SP, R2 SP) are more effective in decreasing cell viability and inhibiting tumorsphere formation compared to the parental strains (T1L and R2). Current studies are focused on sequencing SP clones to identify mutations that enhance BCSC death. We expect these studies to enhance MRV virotherapeutics for combined use with clinically relevant inhibitors (i.e. CDK4/6 inhibitors), anti-estrogens, or immunotherapy to prevent and treat metastatic ER+ breast cancer. Presentation: 6/2/2024

8038 Targeting Breast Cancer Stem Cells with Oncolytic Mammalian Orthoreovirus (MRV)

Abstract Disclosure: N.I. Roman Ortiz: None. J. Davydova: None. P. Danthi: None. J.H. Ostrander: None. Breast cancer is the most frequently diagnosed malignant cancer in women and is the second leading cause of cancer deaths among women in the United States. Patients with ER+ breast cancer can experience recurrence for more than 10 years after initial diagnosis. Breast cancer stem-like cells (BCSC) are slowly proliferative and exist as a minority sub-population (0-5%) within the tumor. Existing treatments target rapidly dividing cells, and BCSC are unresponsive to these therapies. Due to their self-renewal capabilities, BCSCs can fuel recurrence, metastasis, and resistance to therapies. Notably, no FDA-approved therapeutics selectively target BCSCs. Mammalian orthoreovirus (MRV) is an oncolytic virus tested in clinical trials for many cancer types including metastatic breast cancer. MRV was deemed safe but lacked efficacy as standalone treatment. We tested various laboratory MRV strains (T1L, R2) with T3D, a similar strain to the one evaluated in clinical trials. Our studies suggest that T3D is less effective in killing ER+ breast cancer cells and BCSCs compared to T1L and R2. To understand how T1L and R2 are more effective at killing ER+ breast cancer we aim to test the stages of MRV infection and how MRV induces cell death in ER+ therapy sensitive and resistant cells. MRV can enter cells by receptor mediated endocytosis through attachment with Junctional Adhesion Molecule A (JAM-A) and sialic acids as co-receptors. We have found that T1L attaches to cells in a JAM-A-dependent manner in ER+ sensitive cancer cells, while ER+ therapy resistant cells have increased resistance to JAM-A mediated endocytosis. Previous work has shown that apoptosis is involved in MRV-induced cell death. We found that apoptosis inhibitors in MRV-treated cells increase cell viability, suggesting that MRV-induces apoptotic cell death in ER+ breast cancer cells. Our current studies involve using RNA sequencing as a tool to assess gene expression of ER+ therapy sensitive and resistant cells infected with MRV at early and late stages of infection to determine key genes and pathways associated with cell death.We also aim to generate novel MRV strains with enhanced BCSC killing. We used a forward genetic approach and serially passaged MRV strains in BCSC enriched tumorsphere cultures of MCF-7 paclitaxel resistant (TaxR) cells to generate a selective oncolytic virus that can infect and kill BCSCs. Preliminary data has shown that serially passaged (SP) MRV strains (T1L SP, R2 SP) are more effective in decreasing cell viability and inhibiting tumorsphere formation compared to the parental strains (T1L and R2). Current studies are focused on sequencing SP clones to identify mutations that enhance BCSC death. We expect these studies to enhance MRV virotherapeutics for combined use with clinically relevant inhibitors (i.e. CDK4/6 inhibitors), anti-estrogens, or immunotherapy to prevent and treat metastatic ER+ breast cancer. Presentation: 6/2/2024

7880 The Role Of PTHrP In Glucose Metabolism And Insulin Secretion

Abstract Disclosure: I.M. Max-Harry: None. N. Kantake: None. C.S. Nunemaker: None. T.J. Rosol: None. Insulin and glucagon are the two most important hormones for blood glucose homeostasis. Identifying the key players in their regulation will contribute greatly towards combatting types 1 and 2 diabetes. Parathyroid Hormone-related protein (PTHrP), a protein expressed by pancreatic beta cells, has been implicated in various developmental and physiological roles, but particularly, PTHrP increases beta-cell proliferation and insulin secretion in pancreatic islets. Incubating mouse pancreatic islets and Min6 cells with 10nM exogenous PTHrP showed a significant increase in both insulin secretion (for islets, PTHrP: 865.4ng/ml ± 77.66, con: 498.5ng/ml ± 40.63, p=0.024, n=4) and glucagon secretion (PTHrP: 20.87pmol/l ± 3.776, con: 8.798pmol/l ± 1.616, p= 0.068, n=3) after 24hours. In order to further investigate the effects observed, min6 cells were transiently transfected to overexpress PTHrP, and a glucose-stimulated insulin secretion (GSIS) assay was carried out with 2mM and 20mM glucose. The results showed a reduction in basal insulin secretion at 2mM glucose and an increase in insulin secretion at 20mM glucose for the PTHrP transfected cells. PTHrP improved the stimulation index of Min6 cells (PTHrP: 2.279 ± 0.2056, con: 1.659 ± 0.1386, p= 0.03, n=6) and enhanced their sensitivity to glucose. Preliminary proliferation assays showed that cells transfected with PTHrP have increased proliferation and a protection from cell death when incubated in serum-free media. This study, in addition to our previously published research showing that a lack of intact PTHrP leads to islet dysfunction, revealed that PTHrP may be crucial to appropriate glucose sensitivity of beta cells. Further studies are being carried out to understand the mechanism behind these effects and the genes/proteins involved in the regulation of insulin secretion by PTHrP. Presentation: 6/1/2024

NPC1 links cholesterol trafficking to microglial morphology via the gastrosome.

Microglia play important roles in brain development and homeostasis by removing dying neurons through efferocytosis. Morphological changes in microglia are hallmarks of many neurodegenerative conditions, such as Niemann-Pick disease type C. Here, NPC1 loss causes microglia to shift from a branched to an ameboid form, though the cellular basis and functional impact of this change remain unclear. Using zebrafish, we show that NPC1 deficiency causes an efferocytosis-dependent expansion of the microglial gastrosome, a collection point for engulfed material. In vivo and in vitro experiments on microglia and mammalian macrophages demonstrate that NPC1 localizes to the gastrosome, and its absence leads to cholesterol accumulation in this compartment. NPC1 loss and neuronal cell death synergistically affect gastrosome size and cell shape, increasing the sensitivity of NPC1-deficient cells to neuronal cell death. Finally, we demonstrate conservation of cholesterol accumulation and gastrosome expansion in NPC patient-derived fibroblasts, offering an interesting target for further disease investigation.

7323 Prostatic Acid Phosphatase Is Negatively Regulated by Androgens and Persists in Castration-resistant Prostate Cancer

Abstract Disclosure: A. Kirschenbaum: None. P. Cheung: None. S. Yao: None. P. Cheung: None. Background: Prostate cancer (PCa) is the most common cancer and second leading cause of cancer death in American men. Most patients with metastatic PCa respond initially to androgen deprivation therapy (ADT) but the majority will progress to lethal, metastatic, castrate-resistant PCa (mCRPC). The identification of markers of mCRPC that are not regulated or negatively regulated by androgens can serve as markers and therapeutic targets in mCRPC. We hypothesized that prostatic acid phosphatase (PAP), a protein phosphatase and 5’ectonucleotidase that is expressed in both the cytoplasm and transmembrane (TM-PAP) of PCa cells, is negatively regulated by androgen signaling and can serve as a therapeutic target. Methods: PAP protein expression was assessed by immunohistochemistry (IHC) in PCa cell line spheroids (VCaP, 22Rv1, LNCaP, C42B) +/- androgen addition as well as in LNCaP s.c. xenografts +/- castration. Protein expression of PAP was assessed with western blotting in PCa cell lines after treatment with androgens (DHT) and anti-androgen (enzalutamide). Results: In spheroids derived from PCa cell lines, there is some IHC expression of PAP with the strongest staining in VCaP and 22Rv1 spheroids. DHT decreased PAP IHC expression in all spheroids. LNCaP and VCaP s.c. xenografts demonstrated that castration decreased tumor growth rates but that in castrate as well as control tumors PAP expression persisted. All forms of PAP including TM-PAP are expressed in VCaP cell line and were negatively regulated by androgen addition. Conclusions: The identification of markers of mCRPC that are not regulated or are negatively regulated by androgen could help identify recalcitrant tumor cells and mount targeted delivery of therapeutic agents. In several androgen sensitive PCa cell lines, DHT addition decreased PAP expression in spheroids. In vivo, PAP expression persists after castration in spite of decreases in tumor growth rates. Finally, DHT decreases and enzalutamide restores PAP expression in vitro. These data demonstrate that PAP is a more progenitor cell marker in PCa that persists after castration and may be targeted in castration-resistant disease. Presentation: 6/3/2024

8302 A Novel Tool to Map Estrogen Responsiveness Within Estrogen Sensitive Hypothalamic Neurons in Mice

Abstract Disclosure: A.L. Cara: None. A.L. Hall: None. K.K. Soma: None. J. van Veen: None. S.M. Correa: None. Identification of hormone sensitive cells has been traditionally evaluated by hormone receptor expression. Receptor positive cells can be labeled via expression of mRNA transcript via in situ hybridization, presence of protein via immunohistology, or via conditionally-dependent Cre recombinase driven reporter expression. However, these methods used to label and manipulate cells only indicate which cells are capable of sensing hormones, and not necessarily which cells are responding to a hormonal signal in a specific physiologic or behavioral context. Furthermore, broad labeling of all receptor positive cells may not accurately reflect the heterogeneous nature of certain cell populations, particularly in the brain. The hypothalamus is a brain region with well characterized hormone receptor expression, including estrogen receptors, such as ERα (encoded by the Esr1 gene). Estrogens have a broad array of physiologic and behavioral functions which are mediated through hypothalamic nuclei, including thermoregulation, metabolism, and reproduction. Neuronal populations mediating these functions have been characterized, targeted, and manipulated based on ERα expression, but the dynamic response to estrogens in these highly heterogeneous populations has yet to be uncovered. We developed a custom reporter virus that fluorescently labels estrogen-sensitive and responsive cells. The virus contains a flip-excision switch (FLEX) to drive Cre-dependent expression of a FusionRed fluorescent reporter, eight tandem estrogen response elements (ERE), and a destabilized enhanced green fluorescent protein (EGFP) with a 2-hour half-life. The Cre-dependent expression of FusionRed identifies all Esr1-Cre cells at the time of transduction, while the ERE-EGFP identifies a subset of Esr1-Cre+ cells that are actively responding to estrogens via nuclear receptor signaling. We stereotactically injected the ERE-EGFP virus to distinct hypothalamic nuclei of Esr1-Cre female mice. Following transduction, mice were sacrificed during different stages of the estrous cycle. Spatial analysis of ERE-EGFP expression revealed dynamic changes across the estrous cycle, with responses differing based on hypothalamic nucleus. Reporter expression dynamics were compared to estrogen levels measured by LC-MS/MS in ovary, serum, and microdissected brain tissue. A separate group of mice were ovariectomized and given estradiol benzoate (EB) or vehicle control, and neurons were flow sorted for bulk RNA sequencing. We discovered transcriptomic differences in FusionRed+ cells with high or low ERE-EGFP expression, including upregulation of estrogen target genes (e.g., Pgr, encoding progesterone receptor) with EB treatment in ERE-EGFP+ cells. In summary, this new viral reporter reveals divergent responses to estrogens across subsets of estrogen sensitive neurons, brain regions, and hormonal states. Presentation: 6/2/2024

Deciphering MOSPD1's impact on breast cancer progression and therapeutic response.

Motile Sperm Domain-Containing Protein 1 (MOSPD1) has been implicated in breast cancer (BC) pathophysiology, but its exact role remains unclear. This study aimed to assess MOSPD1 expression levels in BC versus normal tissues and investigate its diagnostic potential. MOSPD1 expression was analyzed in BC and normal tissues, with Receiver Operating Characteristic analysis for diagnostic evaluation. Validation was performed using immunohistochemistry. Functional studies included tumor growth assays, MOSPD1 suppression and overexpression experiments, and testing BC cell responses to anti-PD-L1 therapy. MOSPD1 expression was significantly higher in BC samples than normal tissues, correlating with poor clinical outcomes in BC patients. MOSPD1 suppression inhibited tumor growth, while overexpression accelerated it. Silencing MOSPD1 enhanced BC cell sensitivity to anti-PD-L1 therapy and decreased Th2 cell activity. In vivo experiments supported these findings, showing the impact of MOSPD1 on tumor growth and response to therapy. Elevated MOSPD1 levels in BC suggest its potential as a biomarker for adverse outcomes. Targeting MOSPD1, particularly with anti-PD-L1 therapy, may effectively inhibit BC tumor growth and modulate immune responses. This study emphasizes the significance of MOSPD1 in BC pathophysiology and highlights its promise as a therapeutic target.

Highly sensitive reporter cell line for detection of interferon types I-III and their neutralization by antibodies.

Interferons (IFNs) are a critical component of innate immune defenses and limit viral disease severity. To advance studies on IFNs and their neutralization by pathogenic autoantibodies, we generated a Renilla luciferase-based reporter cell line capable of detecting the activities of IFN-Is, IFN-II, and IFN-IIIs. The reporter cell line exhibits a 125- to 2000-fold higher sensitivity to IFNs than a commonly used alternative biological reporter system and allows for a rapid and simple live-cell workflow for detecting low titer amounts of neutralizing anti-IFN antibodies.

Interleukin-2 improves insulin sensitivity through hypothalamic sympathetic activation in obese mice

BackgroundIL-2 regulates T cell differentiation: low-dose IL-2 induces immunoregulatory Treg differentiation, while high-dose IL-2 acts as a potent activator of cytotoxic T cells and NK cells. Therefore, high-dose IL-2 has been studied for use in cancer immunotherapy. We aimed to utilize low-dose IL-2 to treat inflammatory diseases such as obesity and insulin resistance, which involve low-grade chronic inflammation.Main bodySystemic administration of low-dose IL-2 increased Treg cells and decreased inflammation in gonadal white adipose tissue (gWAT), leading to improved insulin sensitivity in high-fat diet-fed obese mice. Additionally, central administration of IL-2 significantly enhanced insulin sensitivity through the activation of the sympathetic nervous system. The sympathetic signaling induced by central IL-2 administration not only decreased interferon γ (IFNγ) + Th1 cells and the expression of pro-inflammatory cytokines, including Il-1β, Il-6, and Il-8, but also increased CD4 + CD25 + FoxP3 + Treg cells and Tgfβ expression in the gWAT of obese mice. These phenomena were accompanied by hypothalamic microgliosis and activation of pro-opiomelanocortin neurons. Furthermore, sympathetic denervation in gWAT reversed the enhanced insulin sensitivity and immune cell polarization induced by central IL-2 administration.ConclusionOverall, we demonstrated that IL-2 improves insulin sensitivity through two mechanisms: direct action on CD4 + T cells and via the neuro-immune axis triggered by hypothalamic microgliosis.