Decreased Tumor Cell Proliferation Research Articles

CD87-targeted BiTE and CAR-T cells potently inhibit invasive nonfunctional pituitary adenomas.

Recently, bispecific T-cell engagers (BiTEs) and chimeric antigen receptor-modified T cells (CAR-Ts) have been shown to have high therapeutic efficacy in hematological tumors. CD87 is highly expressed in solid tumors with an oncogenic function. To assess their cytotoxic effects on invasive nonfunctioning pituitary adenomas (iNFPAs), we first examined CD87 expression and its effects on the metabolism of iNFPA cells. We generated CD87-specific BiTE and CAR/IL-12 T cells, and their cytotoxic effects on iNFPAs cells and in mouse models were determined. CD87 had high expression in iNFPA tissue and cell samples but was undetected in noncancerous brain samples. CD87×CD3 BiTE and CD87 CAR/IL-12 T-cells showed antigenic specificity and exerted satisfactory cytotoxic effects, decreasing tumor cell proliferation in vitro and reducing existing tumors in experimental mice. Overall, the above findings suggest that CD87 is a promising target for the immunotherapeutic management of iNFPAs using anti-CD87 BiTE and CD87-specific CAR/IL-12 T cells.

ETMR-24. SOX2 INFLUENCES IDENTITY OF GLIA-LIKE PROGENITORS AND TUMORIGENESIS IN CHOROID PLEXUS THROUGH LIM HOMEODOMAIN TRANSCRIPTION FACTORS

Abstract Choroid plexus (CP) tumors encompass a spectrum of rare brain neoplasms ranging from benign papilloma (CPP) to aggressive carcinoma (CPC) that collectively affect the pediatric population. Poor outcomes for high-grade lesions and side effects of current treatment paradigms underscore a critical need to develop safer and more efficacious therapies guided by biological understanding of these tumors. We developed mouse models from common molecular defects found in human disease. These models exploit sustained NOTCH signaling activation in the hindbrain upper rhombic lip to generate CPP and CPC. To delineate cellular composition of CP tumors, we conducted snRNA-seq in murine CP tumors. Similar to adult CP, cells in NOTCH-driven CPP partitioned into clusters identified as epithelial, mesenchymal, endothelial, immune, neuronal, and glial cells. Though tumor cells are confined to epithelial compartment based on inferCNV analysis of snRNA-seq data, they are derived from glia-like progenitors. Tumor cells are in a distinct differentiation state characterized by a lack of epithelial maturation, and aberrant expression of markers of neural progenitor/stem-like cells including SRY-Box Transcription Factor 2 (SOX2). Consistently, SOX2 inactivation decreased tumor cell proliferation and blocked NOTCH-driven CP tumor formation. ChIP-seq studies revealed SOX2 binding to promoters of LIM homeodomain transcription factors Lmx1a and Lmx1b. Enforced SOX2 expression activated the expression Lmx1a and Lmx1b, whereas Sox2 loss reduced their expressions in tumor cells. Importantly, knockdown of Lmx1a or Lmx1b decreased tumor cell proliferation, whereas overexpression of Lmx1a/b rescued proliferation of tumor cells subjected to SOX2 suppression. Contextualizing these results in CP development, SOX2 critically maintains progenitor cell identity through regulating Lmx1a/b expression in the rhombic lip. Finally, analysis of human CP tumor samples revealed abnormal expressions of SOX2 and LMX1A. Together, these results indicate that oncogenic signaling subverts SOX2 transcriptional programs that specify normal progenitor identity and lock tumor cells in unique differentiation state to facilitate CP tumor growth.

Glucocorticoid receptor-mediated oncogenic activity is dependent on breast cancer subtype

Breast cancer incidence has been steadily rising and is the leading cause of cancer death in women due to its high metastatic potential. Individual breast cancer subtypes are classified by both cell type of origin and receptor expression, namely estrogen, progesterone and human epidermal growth factor receptors (ER, PR and HER2). Recently, the importance and context-dependent role of glucocorticoid receptor (GR) expression in the natural history and prognosis of breast cancer subtypes have been uncovered. In ER-positive breast cancer, GR expression is associated with a better prognosis as a result of ER-GR crosstalk. GR appears to modulate ER-mediated gene expression resulting in decreased tumor cell proliferation and a more indolent cancer phenotype. In ER-negative breast cancer, including GR-positive triple-negative breast cancer (TNBC), GR expression enhances migration, chemotherapy resistance and cell survival. In invasive lobular carcinoma, GR function is relatively understudied, and more work is required to determine whether lobular subtypes behave similarly to their invasive ductal carcinoma counterparts. Importantly, understanding GR signaling in individual breast cancer subtypes has potential clinical implications because of the recent development of highly selective GR non-steroidal ligands, which represent a therapeutic approach for modulating GR activity systemically.

First-in-Class Humanized Antibody against Alternatively Spliced Tissue Factor Augments Anti-Metastatic Efficacy of Chemotherapy in a Preclinical Model of Pancreatic Ductal Adenocarcinoma.

Alternatively spliced tissue factor (asTF) promotes the progression of pancreatic ductal adenocarcinoma (PDAC) by activating β1-integrins on PDAC cell surfaces. hRabMab1, a first-in-class humanized inhibitory anti-asTF antibody we recently developed, can suppress PDAC primary tumor growth as a single agent. Whether hRabMab1 has the potential to suppress metastases in PDAC is unknown. Following in vivo screening of three asTF-proficient human PDAC cell lines, we chose to make use of KRAS G12V-mutant human PDAC cell line PaCa-44, which yields aggressive primary orthotopic tumors with spontaneous spread to PDAC-relevant anatomical sites, along with concomitant severe leukocytosis. The experimental design featured orthotopic tumors formed by luciferase labeled PaCa-44 cells; administration of hRabMab1 alone or in combination with gemcitabine/paclitaxel (gem/PTX); and the assessment of the treatment outcomes on the primary tumor tissue as well as systemic spread. When administered alone, hRabMab1 exhibited poor penetration of tumor tissue; however, hRabMab1 was abundant in tumor tissue when co-administered with gem/PTX, which resulted in a significant decrease in tumor cell proliferation; leukocyte infiltration; and neovascularization. Gem/PTX alone reduced primary tumor volume, but not metastatic spread; only the combination of hRabMab1 and gem/PTX significantly reduced metastatic spread. RNA-seq analysis of primary tumors showed that the addition of hRabMab1 to gem/PTX enhanced the downregulation of tubulin binding and microtubule motor activity. In the liver, hRabMab1 reduced liver metastasis as a single agent. Only the combination of hRabMab1 and gem/PTX eliminated tumor cell-induced leukocytosis. We here demonstrate for the first time that hRabMab1 may help suppress metastasis in PDAC. hRabMab1's ability to improve the efficacy of chemotherapy is significant and warrants further investigation.

Role of INPP4B in the proliferation, migration, invasion, and survival of human endometrial cancer cells.

Inositol polyphosphate 4-phosphatase type II (INPP4B) has been identified as a tumor repressor in several human cancers while its role in endometrial cancer has not been investigated yet. Therefore, the current study was designed to determine whether INPP4B participates in the progression of endometrial cancer by utilizing clinical data and experimental determination. We first include six chemotherapy-treated patients with recurrent and metastatic endometrioid carcinoma to determine the relationship between INPP4B mutation and relative tumor burden. By using siRNA-mediated gene silencing and vector-mediated gene overexpression, we further determined the effect of manipulating INPP4B expression on the proliferation, invasion, and survival of endometrial cancer cells. Furthermore, the repressing effect of INPP4B together with its role in chemotherapy was further validated by xenograft tumor-bearing mice models. Western blot analysis was used to explore further downstream signaling modulated by INPP4B expression manipulation. Two of the patients were found to have INPP4B mutations and the mutation frequency of INPP4B increased during the progression of chemotherapy resistance. Endometrial cancer cells with silenced INPP4B expression were found to have promoted tumor cell proliferation, invasion, and survival. Endometrial cancer cells overexpressing INPP4B were found to have decreased tumor cell proliferation, invasion, and survival. An in vivo study using six xenograft tumor-bearing mice in each group revealed that INPP4B overexpression could suppress tumor progression and enhance chemosensitivity. Furthermore, INPP4B overexpression was found to modulate the activation of Wnt3a signaling. The current study suggested that INPP4B could be a suppressor in endometrial cancer progression and might be a target for endometrial cancer treatment. Also, INPP4B might serve as a predictor of chemosensitivity determination.

Efficacy and safety of a combination anti-tumor against breast cancer in the central and south of Iraq.

Aim: To explore efficacy and safety of combined anti-tumor treatments against breast cancer to help health professionals and decision-makers take strategies to slow the spread of breast cancer and improve women's health. Material and Methods: A cross-sectional study was used by various Iraqi governments. The survey was conducted between July 1, 2022 and April 30, 2023. The study depended on describing studying of 100 patients in detail and with long-term follow-up who go to hospitals and take anti-cancer medications from different provinces of central and south Iraq. The questionnaire form contains 17 fields divided into three sections. The diagnosis tumor before and after treatment parameters: histopathology, CT-scan, tumor marker (Nuclear protein Ki67, Cancer antigen 153 (CA 153), human epidermal growth factor receptor 2, and carcinoembryonic antigen), renal function tests, liver function tests, and Complete Blood Count. Results: The use of anti-tumor medications was coupled with markedly decreased tumor cell proliferation via reduced biomarker levels of cancer (CA-15-3), HER-2, and Ki-67 levels, and decreased the mammary ductal epithelium's thickness. Conclusions: The study showed efficiency of combination medications to prevent breast cancer cell development by preventing cell growth.

A novel treatment to enhance survival for end stage triple negative breast cancer using repurposed veterinary anthelmintics combined with gut‑supporting/immune enhancing molecules.

Patients with end‑stage metastatic disease have limited treatment options and those diagnosed with triple negative breast cancer (Her2, Estrogen receptor, Progesterone receptor) have a poor prognosis. Using a triple negative mammary tumor model selected for brain metastasis (4T1Br4) in the mouse, treatment options that may increase survival when therapeutics are applied at post‑metastasis were assessed. Anti‑parasitic benzimidazoles (BZs) destabilize microtubules, inhibit metabolic pathways, reduce cell proliferation, and induce apoptosis in tumor cells. Co‑administration of two BZs was selected, oxfendazole (OFZ) and parbendazole (PBZ), shown to overcome resistance development in anthelmintic effects by imposing metabolic delay to assess if multiple BZ approach is also suitable to enhance anticancer effects. It has been previously reported that treatment of mammary tumor‑bearing mice at an early stage with chitin microparticles (CMPs) decreased tumor growth and metastases by enhancing both innate M1 macrophage and TH1 adaptive immune response. Oral administration of CMPs was previously revealed to affect the gut in intestinal inflammation. A combination BZ (OFZ/PBZ) and CMP treatment was tested to target tumor development and metastasis and effects were compared in response to monotherapies of the same compounds or to untreated mice. The results demonstrated increased survival, decreased tumor cell proliferation, decreased metastasis in lungs and brain, increased levels of fecal SCFAs butyric, acetic, propionic and valeric acids with increased butyric and propionic acid levels in brain biopsies in combination treated compared with untreated mice. At the primary tumor, SCFA receptor FFAR2 expression was increased in combination treatment compared with untreated mice, suggestive of a non‑invasive cancer phenotype. The superior cytotoxic effects of OFZ/PBZ were confirmed as opposed to single treatment with OFZ or PBZ using 3D spheroids generated from a human breast cancer cell line, MDA‑MB‑468. These data are compelling for treatment option possibility even at late stages of metastasized breast cancer.

Target Separation and Potential Anticancer Activity of Withanolide-Based Glucose Transporter Protein 1 Inhibitors from Physalis angulata var. villosa.

The glucose transporter 1 (GLUT1) protein is involved in the basal-level absorption of glucose in tumor cells. Inhibiting GLUT1 decreases tumor cell proliferation and induces tumor cell damage. Natural GLUT1 inhibitors have been studied only to a small extent, and the structures of known natural GLUT1 inhibitors are limited to a few classes of natural products. Therefore, discovering and researching other natural GLUT1 inhibitors with novel scaffolds are essential. Physalis angulata L. var. villosa is a plant known as Mao-Ku-Zhi (MKZ). Withanolides are the main phytochemical components of MKZ. MKZ extracts and the components of MKZ exhibited antitumor activity in recent pharmacological studies. However, the antitumor-active components of MKZ and their molecular mechanisms remain unknown. A cell membrane-biomimetic nanoplatform (CM@Fe3O4/MIL-101) was used for target separation of potential GLUT1 inhibitors from MKZ. A new withanolide, physagulide Y (2), together with six known withanolides (1, 3-7), was identified as a potential GLUT1 inhibitor. Physagulide Y was the most potent GLUT1 inhibitor, and its antitumor activity and possible mechanism of action were explored in MCF-7 human cancer cells. These findings advance the development of technologies for the targeted separation of natural products and identify a new molecular framework for the investigation of natural GLUT1 inhibitors.

Abstract B033: Multiplex analysis of the tumor immune microenvironment during treatment with atezolizumab/pelareorep/letrozole reveals novel immune-tumor interactions

Abstract Background: Pelareorep (pela) is a non-modified intravenously administered oncolytic reovirus exhibiting effective tumor suppression through both innate and adaptive immune responses, as well as direct tumor lysis. Findings from the AWARE-1 window of opportunity study previously demonstrated the synergistic potential of combining pela with atezolizumab (atezo), showcasing promising immunological reactions within tumors of early breast cancer (eBC) patients. To gain deeper insights into the complex tumor immune microenvironment (TiME) pre- and post-treatment, we employed imaging mass cytometry (IMC) to conduct high-dimensional, single-cell analysis of tissue samples. Methods: Patients (n=10) received pela (days 1, 2 and 8, 9), atezolizumab (day 3), and letrozole (day 1 to 21). Tumor biopsies (FFPE samples) were collected pre-treatment on day 3 (prior to atezolizumab administration) and on day ~21 (surgical excision). Samples from 8 out of 10 patients were subjected to IMC with a comprehensive panel of 37 antibodies for single cell investigation of TiME changes. Tumor, proliferation, T cell, macrophage, NK, and immunoregulatory markers were included in the panel. Results: Our first pass analysis of IMC images, showed an increase in proliferating (Ki67+) cytotoxic T cells adjacent to apoptotic (caspase 3+) tumor cells post-treatment (both D3 and D21) samples indicating immunogenic cell death. Conversely, we observed a decrease in Ki67+ and ER-positive tumor cells after treatment indicating decreased tumor cell proliferation and hormone expression. In 3 out of 8 patients, treatment was associated with a shift in monocyte/macrophages from an M1 (CD68+/CD163-) to M2 (CD68+/CD163+) phenotype associated with significant tumor infiltration. Surprisingly, in these patients we also noted a significant increase in apoptotic M2 macrophages on D21. Consistent with the known immune priming effects of pela, both PD-1 and PD-L1 increased on D3. Subsequently, on day 21, post atezo, tumor PD-L1 decreased on tumor cells while PD-1 expression persisted. Pela induced IDO expression on both tumor and monocyte/macrophage cells. Unlike its effect on PD-L1, atezo did not appear to attenuate IDO expression on day 21. We were also able to detect a treatment related increase in immune cell perivascular localization on D3 providing further evidence of TiME priming. Conclusions: The immune system plays a crucial role in regulating cancer progression; however, our understanding of immune interactions with tumors remains limited. Our study utilizing IMC revealed complex immune-tumor interactions changes during treatment with atezo/pela/letrozole. These findings provide valuable insights into the intricate dynamics of the TiME and may inform new therapeutic combination approaches in breast cancer treatment. Citation Format: Homa Dadrastoussi, Julian Olea, Eduardo Fernandez Hernandez, Hugo Lara Martinez, Kaijin Wu, Houra Loghmani, Thomas Heineman, Richard Trauger, Matt Coffey, Akil Merchant, Kevin Kelly. Multiplex analysis of the tumor immune microenvironment during treatment with atezolizumab/pelareorep/letrozole reveals novel immune-tumor interactions [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr B033.

Entecavir: A Review and Considerations for Its Application in Oncology.

Entecavir (ETV) is a drug used as a first-line treatment for chronic hepatitis B (CHB) virus infection because it is a guanosine nucleoside analogue with activity against the hepatitis B virus polymerase. The ETV dosage can range from 0.5 mg to 1 mg once a day and the most common side effects include headache, insomnia, fatigue, dizziness, somnolence, vomiting, diarrhea, nausea, dyspepsia, and increased liver enzyme levels. In addition to its conventional use, ETV acts as an inhibitor of lysine-specific demethylase 5B (KDM5B), an enzyme that is overexpressed in breast, lung, skin, liver, and prostate tumors and is involved in the hormonal response, stem cell regeneration, genomic stability, cell proliferation, and differentiation. The KDM5B enzyme acts as a transcriptional repressor in tumor suppressor genes, silencing them, and its overexpression leads to drug resistance in certain tumor types. Furthermore, the literature suggests that KDM5B activates the PI3K/AKT signaling pathway, while reducing KDM5B expression decreases AKT signaling, resulting in decreased tumor cell proliferation. In silico studies have demonstrated that ETV can inhibit tumor cell proliferation and induce apoptosis by reducing KDM5B expression. ETV also appears to inhibit PARP-1, has a high genetic barrier, reducing the chance of resistance development, and can also prevent the reactivation of the hepatitis B virus in cancer patients, which have proven to be significant advantages regarding its use as a repurposed drug in oncology. Therefore, ETV holds promise beyond its original therapeutic indication.

Significance of NotchScore and JAG1 in predicting prognosis and immune response of low-grade glioma.

Low-grade glioma (LGG) is a prevalent malignant tumor in the intracranial region. Despite the advancements in treatment methods for this malignancy over the past decade, significant challenges still persist in the form of drug resistance and tumor recurrence. The Notch signaling pathway plays essential roles in many physiological processes as well as in cancer development. However, the significance of the pathway and family genes in LGG are poorly understood. We conducted gene expression profiling analysis using the TCGA dataset to investigate the gene set associated with the Notch signaling pathway. we have proposed a metric called "NotchScore" that quantifies the strength of the Notch signaling pathway and enables us to assess its significance in predicting prognosis and immune response in LGG. We downregulated JAG1 in low-grade gliomas to assess its influence on the proliferation and migration of these tumors. Ultimately, we determined the impact of the transcription factor VDR on the transcription of PDL1 through chip-seq data analysis. Our findings indicate that tumors with a higher NotchScore, exhibit poorer prognosis, potentially due to their ability to evade the anti-tumor effects of immune cells by expressing immune checkpoints. Among the genes involved in the Notch signaling pathway, JAG1 has emerged as the most representative in terms of capturing the characteristics of both NotchScore and Notch pathways. The experimental results demonstrate that silencing JAG1 yielded a significant decrease in tumor cell proliferation in LGG cell lines. Our study revealed mechanisms by which tumors evade the immune system through the modulation of PDL1 transcription levels via the PI3K-Akt signaling pathway. Additionally, JAG1 potentially influences PDL1 in LGG by regulating the PI3K-Akt signaling pathway and the expression of the transcription factor VDR. These findings contribute to our understanding of immune evasion by tumors in LGG. The insights gained from this research may have implications for the development of therapeutic interventions for LGG.

BIOM-29. FIBRONECTIN TYPE III DOMAIN CONTAINING 3B AS PROGNOSTIC BIOMARKER AND REGULATORY TARGET FOR MALIGNANT BRAIN TUMOR

Abstract Malignant brain tumor (MBT) is an aggressive tumor with high drug-resistance and recurrence rates. Using ‘Oncopression’ big data analysis, we found that a fibronectin-related protein, fibronectin type III domain containing 3B (FNDC3B), was specifically overexpressed in brain tumor patients and conducted a pilot and mechanism study on the role of FNDC3B in MBT. We evaluated the functional significance of FNDC3B in MBT using FNDC3B specific siRNA and performing cell viability assay, real-time qPCR, Western blot, 3D-invasion assay, and wound healing assay. Furthermore, using proteome profiler human phospho-kinase arrays, we investigated the correlated signaling which activated while FNDC3B-mediated MBT cell progression. We found that down-regulation of FNDC3B decreased tumor cell proliferation, migratory and invasiveness properties as well as stemness phenotype which are hallmarks of cancer progression. Furthermore, we demonstrate that PI3K/AKT signaling pathways were involved mainly in FNDC3B-related tumor growth and mesenchymal phenotypes. Although follow-up studies are necessary, the results of this study suggest that FNDC3B is worth investigating as a novel alternative diagnostic and therapeutic target candidate for MBT.

WD Repeat and HMG Box DNA Binding Protein 1: An Oncoprotein at the Hub of Tumorigenesis and a Novel Therapeutic Target.

WD repeat and HMG-box DNA binding protein 1 (WDHD1) is a highly conserved gene from yeast to humans. It actively participates in DNA replication, playing a crucial role in DNA damage repair and the cell cycle, contributing to centromere formation and sister chromosome segregation. Notably, several studies have implicated WDHD1 in the development and progression of diverse tumor types, including esophageal carcinoma, pulmonary carcinoma, and breast carcinoma. Additionally, the inhibitor of WDHD1 has been found to enhance radiation sensitivity, improve drug resistance, and significantly decrease tumor cell proliferation. This comprehensive review aims to provide an overview of the molecular structure, biological functions, and regulatory mechanisms of WDHD1 in tumors, thereby establishing a foundation for future investigations and potential clinical applications of WDHD1.

Liver X receptors induce antiproliferative effects in basal-like breast cancer.

Liver X receptors (LXRs) are nuclear transcription factors important in the regulation of cholesterol transport, and glucose and fatty acid metabolism. The antiproliferative role of LXRs has been studied in a variety of malignancies and may represent a therapeutic opportunity in cancers lacking targeted therapies, such as triple-negative breast cancer. In this study, we investigated the impact of LXR agonists alone and in combination with carboplatin in preclinical models of breast cancer. In vitro experiments revealed a dose-dependent decrease in tumor cell proliferation in estrogen receptor-positive breast cancer cells, whereas LXR activation in vivo resulted in an increased growth inhibitory effect in a basal-like breast cancer model (in combination with carboplatin). Functional proteomic analysis identified differences in protein expression between responding and nonresponding models related to Akt activity, cell-cycle progression, and DNA repair. Furthermore, pathway analysis suggested that the LXR agonist in combination with carboplatin inhibits the activity of targets of E2F transcription factors and affects cholesterol homeostasis in basal-like breast cancer.

Ultra-high dose-rate proton FLASH improves tumor control

Background and purposeProton radiotherapy (PRT) offers potential benefits over other radiation modalities, including photon and electron radiotherapy. Increasing the rate at which proton radiation is delivered may provide a therapeutic advantage. Here, we compared the efficacy of conventional proton therapy (CONVpr) to ultrahigh dose-rate proton therapy, FLASHpr, in a mouse model of non-small cell lung cancers (NSCLC). Materials and methodsMice bearing orthotopic lung tumors received thoracic radiation therapy using CONVpr (<0.05 Gy/s) and FLASHpr (>60 Gy/s) dose rates. ResultsCompared to CONVpr, FLASHpr was more effective in reducing tumor burden and decreasing tumor cell proliferation. Furthermore, FLASHpr was more efficient in increasing the infiltration of cytotoxic CD8+ T-lymphocytes inside the tumor while simultaneously reducing the percentage of immunosuppressive regulatory T-cells (Tregs) among T-lymphocytes. Also, compared to CONVpr, FLASHpr was more effective in decreasing pro-tumorigenic M2-like macrophages in lung tumors, while increasing infiltration of anti-tumor M1-like macrophages. Finally, FLASHpr treatment reduced expression of checkpoint inhibitors in lung tumors, indicating reduced immune tolerance. ConclusionsOur results suggest that FLASH dose-rate proton delivery modulates the immune system to improve tumor control and might thus be a promising new alternative to conventional dose rates for NSCLC treatment.

Abstract B074: Targeting CBP/p300 and its downstream transcriptional machinery in advanced PCa

Abstract Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men in the US. There is a largely unmet clinical need to identify and develop novel strategies, that work either alone or in concert with AR-directed therapeutics, to combat CRPC. The highly conserved histone acetyltransferases CBP/p300 are potent co-activators for AR, and high p300 expression is associated with locally advanced disease and castration-resistant AR function. This study shows that CBP and p300 are highly expressed and correlate closely with AR gene expression and AR activity score in primary PCa and CRPC. By employing clinically relevant PCa models, the clinical significance of CBP/p300 expression in PCa patients as well as mechanistic evaluation of CBP/p300 transcriptional reprogramming and DNA damage response pathways have been undertaken. The molecular response to CBP/p300 inhibition will be assessed to discern novel metrics for precision medicine for PCa patients to improve therapeutic efficacy. Previous studies have relied on non-specific compounds and genetic silencing to target CBP/p300. CCS1477 (inobrodib) is a first-in-class bromodomain inhibitor developed by Cell Centric and targeted to inhibit CBP/p300 mediated bromodomain activity, and thus regulate cell survival. Inhibition of the CBP/p300 bromodomain resulted in significant downregulation of AR-FL, AR-V7, and its targets’ mRNA expression, as well as inhibition of associated factors such c-MYC and its downstream targets, in multiple PCa models. Transcriptomic analysis indicated that both CBP and p300 expression correlate with expression of genes involved in double strand break (DSB) DNA repair process including homologous recombination (HR) and non-homologous end joining (NHEJ) in both primary PCa and CRPC models. CCS1477 directly impacted DNA damage response and repair dynamics, as shown via delay in time to resolution of DNA damage foci formation, including RAD51 and γH2AX foci. Inhibition of CBP/p300 activity decreased tumor cell proliferation, blocked CRPC xenograft growth in vivo, and decreased proliferation ex vivo in patient-derived prostate tumor explants. Importantly, CBP/p300 expression correlated with HR genes in human prostate tissue samples in different cohorts. Lastly, inhibition of CBP/p300 activity also decreased HR gene expression in patients further supporting the essential role CBP/p300 plays in DNA repair. In sum, CBP/p300 inhibition mediates HR repair and impacts patient outcome. In conclusion, these studies identify CBP/p300 as a driver of PCa tumorigenesis through coordinated control of critical transcriptional events and lay the groundwork to optimize therapeutic strategies for advanced PCa via CBP/p300 inhibition, potentially in combination with AR-directed therapies. Combined, these studies have the capacity for significant near-term impact in the prevention and/or management of metastatic disease. Citation Format: Sumaira Sardar, Lakshmi Ravindranath, Christopher McNair, Saswati Chand, Wei Yuan, Denisa Bogdan, Jon Welti, Adam Sharp, Matthew Schiewer, Lisa Butler, Johann DeBono, Kris Frese, Nigel Brooks, Neil Pegg, Karen Knudsen, Ayesha A. Shafi. Targeting CBP/p300 and its downstream transcriptional machinery in advanced PCa [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr B074.

Antitumor Activity of Luteolin Against Ehrlich Solid Carcinoma in Rats via Blocking Wnt/β-Catenin/SMAD4 Pathway.

Background Ehrlich solid carcinoma (ESC) is characterized by rapid proliferation and a short survival time. Because Ehrlich ascites carcinoma (EAC) resembles human cancer cells, Ehrlich solid and ascetic forms are commonly used to determine the anticancer effects of various compounds. Luteolin is a flavonoid compound found in many dietary sources, including carrots, peppers, celery, olive oil, peppermint, and oregano. Luteolin has potent anti-inflammatory, antidiabetic, antitumor, and antiapoptotic activities. Aims This study aims to investigate the antitumor activity of luteolin against ESC in rats by affecting the Wnt/β-catenin/SMAD4 pathway. Methods We introduced 0.15 ml of Ehrlich cells (2 × 106) ESC into the left hind thighs of rats. After eight days of inoculation, the rats orally received 25 mg/kg of luteolin daily. We stained sections of tumor tissues with Masson's trichrome. We used another part of the tumor tissue to assess gene and protein expression of Wnt, β-catenin, E-cadherin, and SMAD4. Results Treatment of carcinoma rats with luteolin increased the mean survival time and reduced tumor volume and weight. In addition, examination of tumor tissue stained with Masson's trichrome showed loosely to densely packed collagen fibers in between neoplastic cells and scattered papillary expansion of a loose blue band of collagen expression along the covering adipose connective tissue and extending in a fine strand in between muscle fibers, which was ameliorated by treating rats with luteolin. Finally, treating ESC in rats with luteolin overexpressed E-cadherin and downregulated Wnt, β-catenin, and SMAD4. Conclusions We found luteolin has antineoplastic activity against ESC by reducing tumor size and weight while improving the structure of muscle cells. It works by suppressing Wnt, β-catenin, and SMAD4, resulting in decreased tumor cell proliferation and differentiation. Additionally, luteolin overexpresses E-cadherin, leading to reduced tumor cell invasion and metastasis.

Targeting B7-H3-A Novel Strategy for the Design of Anticancer Agents for Extracranial Pediatric Solid Tumors Treatment.

Recent scientific data recognize the B7-H3 checkpoint molecule as a potential target for immunotherapy of pediatric solid tumors (PSTs). B7-H3 is highly expressed in extracranial PSTs such as neuroblastoma, rhabdomyosarcoma, nephroblastoma, osteosarcoma, and Ewing sarcoma, whereas its expression is absent or very low in normal tissues and organs. The influence of B7-H3 on the biological behavior of malignant solid neoplasms of childhood is expressed through different molecular mechanisms, including stimulation of immune evasion and tumor invasion, and cell-cycle disruption. It has been shown that B7-H3 knockdown decreased tumor cell proliferation and migration, suppressed tumor growth, and enhanced anti-tumor immune response in some pediatric solid cancers. Antibody-drug conjugates targeting B7-H3 exhibited profound anti-tumor effects against preclinical models of pediatric solid malignancies. Moreover, B7-H3-targeting chimeric antigen receptor (CAR)-T cells demonstrated significant in vivo activity against different xenograft models of neuroblastoma, Ewing sarcoma, and osteosarcoma. Finally, clinical studies demonstrated the potent anti-tumor activity of B7-H3-targeting antibody-radioimmunoconjugates in metastatic neuroblastoma. This review summarizes the established data from various PST-related studies, including in vitro, in vivo, and clinical research, and explains all the benefits and potential obstacles of targeting B7-H3 by novel immunotherapeutic agents designed to treat malignant extracranial solid tumors of childhood.

Abstract 2784: JW-1-283 inhibits melanoma tumor growth via the stabilization of p53 pathway

Abstract Melanoma is the most lethal skin cancer, with the increasing incidence in the past decade. Despite the significant advancements in immune therapy and targeted therapy, the overall prognosis for metastatic melanoma remains unsatisfactory. TP53 is a tumor suppressor, but its wildtype is inactivated in about 90% of melanoma. Since activated p53 can promote cancer cell apoptosis and thus effectively inhibit tumor growth and tumor metastasis, reactivation of p53 is considered a promising strategy for cancer therapy. Herein, we report a recently developed small molecule compound, JW-1-283, targeting the interactions between MDM2 E3 ubiquitin-protein ligase and p53 protein. In vitro, JW-1-283 showed potent cytotoxicity against A375 melanoma cell line (IC50 2.2±0.3 μM) which has wildtype p53, but its potency is substantially reduced in two other melanoma cell lines with either p53 mutation (M14) or p53 null (RPMI-7951) status. Treatment with JW-1-283 significantly dose-dependently reduced the stemness in A375 melanoma cells, as indicated by low numbers of colony formation, impaired tumor sphere formation abilities, and inhibition of cancer cell migration. Mechanistically, JW-1-283 disrupts the p53-MDM2 interaction, prevents p53 and MDM2 degradation in the existence of cycloheximide, and induces p38 and p53 phosphorylation in the apoptotic pathway. Genetic knockdown of p38 by siRNA further confirmed that the stabilized p53 could be subsequently phosphorylated by p38, leading to induced apoptosis as well as S phase cell cycle arrest. In vivo, when A375 tumors grown in NSG mice were treated with 7.5 mg/kg of JW-1-283 intraperitoneally every other day for a consecutive of 16 days, significant inhibition of tumor growth was observed, along with decreased tumor cell proliferation, tumor angiogenesis, and enhanced tumor cell apoptosis. In summary, this work provides the initial proof-of-concept of developing the JW-1-283 scaffold as a potential strategy for advanced melanoma, which inhibits tumor growth by activating the p53 signaling pathway. Citation Format: Yang Xie, Kelli Hartman, Zhongzhi Wu, Wei Li. JW-1-283 inhibits melanoma tumor growth via the stabilization of p53 pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2784.

Abstract 1449: Targeting CBP/p300 and its downstream transcriptional machinery in advanced prostate cancer

Abstract Prostate cancer (PCa) is the second leading cause of cancer-related deaths in men in the US. There is a largely unmet clinical need to identify and develop novel strategies, that work either alone or in concert with AR-directed therapeutics, to combat CRPC. The highly conserved histone acetyltransferases CBP/p300 are potent co-activators for AR, and high p300 expression is associated with locally advanced disease and castration-resistant AR function. This study shows that CBP and p300 are highly expressed and correlate closely with AR gene expression and AR activity score in primary PCa and CRPC. By employing clinically relevant PCa models, the clinical significance of CBP/p300 expression in PCa patients as well as mechanistic evaluation of CBP/p300 transcriptional reprogramming and DNA damage response pathways have been undertaken. The molecular response to CBP/p300 inhibition will be assessed to discern novel metrics for precision medicine for PCa patients to improve therapeutic efficacy. Previous studies have relied on non-specific compounds and genetic silencing to target CBP/p300. CCS1477 (inobrodib) is a first-in-class bromodomain inhibitor developed by Cell Centric and targeted to inhibit CBP/p300 mediated bromodomain activity, and thus regulate cell survival. Inhibition of the CBP/p300 bromodomain resulted in significant downregulation of AR-FL, AR-V7, and its targets’ mRNA expression, as well as inhibition of associated factors such c-MYC and its downstream targets, in multiple PCa models. Transcriptomic analysis indicated that both CBP and p300 expression correlate with expression of genes involved in double strand break (DSB) DNA repair process including homologous recombination (HR) and non-homologous end joining (NHEJ) in both primary PCa and CRPC models. CCS1477 directly impacted DNA damage response and repair dynamics, as shown via delay in time to resolution of DNA damage foci formation, including RAD51 and γH2AX foci. Inhibition of CBP/p300 activity decreased tumor cell proliferation, blocked CRPC xenograft growth in vivo, and decreased proliferation ex vivo in patient-derived prostate tumor explants. Importantly, CBP/p300 expression correlated with HR genes in human prostate tissue samples in different cohorts. Lastly, inhibition of CBP/p300 activity also decreased HR gene expression in patients further supporting the essential role CBP/p300 plays in DNA repair. In sum, CBP/p300 inhibition mediates HR repair and impacts patient outcome. In conclusion, these studies identify CBP/p300 as a driver of PCa tumorigenesis through coordinated control of critical transcriptional events and lay the groundwork to optimize therapeutic strategies for advanced PCa via CBP/p300 inhibition, potentially in combination with AR-directed therapies. Combined, these studies have the capacity for significant near-term impact in the prevention and/or management of metastatic disease. Citation Format: Sumaira Sardar, Lakshmi Ravindranath, Christopher McNair, Saswati Chand, Wei Yuan, Denisa Bogdan, Jon Welti, Adam Sharp, Matthew Schiewer, Lisa Butler, Johann de Bono, Kris Frese, Nigel Brooks, Neil Pegg, Karen Knudsen, Ayesha Shafi. Targeting CBP/p300 and its downstream transcriptional machinery in advanced prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1449.