Potential Therapeutic Target In Cancer Research Articles

RHNO1: at the crossroads of DNA replication stress, DNA repair, and cancer.

The DNA replication stress (DRS) response is a crucial homeostatic mechanism for maintaining genome integrity in the face of intrinsic and extrinsic barriers to DNA replication. Importantly, DRS is often significantly increased in tumor cells, making tumors dependent on the cellular DRS response for growth and survival. Rad9-Hus1-Rad1 Interacting Nuclear Orphan 1 (RHNO1), a protein involved in the DRS response, has recently emerged as a potential therapeutic target in cancer. RHNO1 interacts with the 9-1-1 checkpoint clamp and TopBP1 to activate the ATR/Chk1 signaling pathway, the crucial mediator of the DRS response. Moreover, RHNO1 was also recently identified as a key facilitator of theta-mediated end joining (TMEJ), a DNA repair mechanism implicated in cancer progression and chemoresistance. In this literature review, we provide an overview of our current understanding of RHNO1, including its structure, function in the DRS response, and role in DNA repair, and discuss its potential as a cancer therapeutic target. Therapeutic targeting of RHNO1 holds promise for tumors with elevated DRS as well as tumors with DNA repair deficiencies, including homologous recombination DNA repair deficient (HRD) tumors. Further investigation into RHNO1 function in cancer, and development of approaches to target RHNO1, are expected to yield novel strategies for cancer treatment.

MCM8 promotes gastric cancer progression through RPS15A and predicts poor prognosis.

Gastric cancer (GC) is the fourth leading cause of cancer-related death worldwide. Minichromsome maintenance proteins family member 8 (MCM8) assists DNA repair and DNA replication. MCM8 exerts tumor promotor function in multiple digestive system tumors. MCM8 is also considered as a potential cancer therapeutic target. Bioinformatics methods were used to analyze MCM8 expression and clinicopathological significance. MCM8 expression was detected by immunohistochemistry (IHC) staining and qRT-PCR. MCM8 functions in GC cell were explored by Celigo cell counting, colony formation, wound-healing, transwell, and annexin V-APC staining assays. The target of MCM8 was determined by human gene expression profile microarray. Human phospho-kinase array kit evaluated changes in key proteins after ribosomal protein S15A (RPS15A) knockdown. MCM8 functions were reassessed in xenograft mouse model. IHC detected related proteins expression in mouse tumor sections. MCM8 was significantly upregulated and predicted poor prognosis in GC. High expression of MCM8 was positively correlated with lymph node positive (p < 0.001), grade (p < 0.05), AJCC Stage (p < 0.001), pathologic T (p < 0.01), and pathologic N (p < 0.001). MCM8 knockdown inhibited proliferation, migration, and invasion while promoting apoptosis. RPS15A expression decreased significantly after MCM8 knockdown. It was also the only candidate target, which ranked among the top 10 downregulated differentially expressed genes (DEGs) in sh-MCM8 group. RPS15A was identified as the target of MCM8 in GC. MCM8/RPS15A promoted phosphorylation of P38α, LYN, and p70S6K. Moreover, MCM8 knockdown inhibited tumor growth, RPS15A expression, and phosphorylation of P38α, LYN, and p70S6K invivo. MCM8 is an oncogene and predicts poor prognosis in GC. MCM8/RPS15A facilitates GC progression.

Structural analysis of the FERM domain of human protein tyrosine phosphatase non-receptor type 21.

Protein tyrosine phosphatase non-receptor type 21 (PTPN21) is a cytosolic protein tyrosine phosphatase that regulates cell growth and invasion. Due to its oncogenic properties, PTPN21 has recently emerged as a potential therapeutic target for cancer. In this study, the three-dimensional structure of the PTPN21 FERM domain was determined at 2.1 Å resolution by X-ray crystallography. The crystal structure showed that this domain harbors canonical FERM folding and consists of three subdomains that are tightly packed via highly conserved intramolecular hydrophobic interactions. Consistent with this, the PTPN21 FERM domain shares high structural homology with several other FERM domains. Moreover, structural superimposition demonstrated two putative protein-binding sites of the PTPN21 FERM domain, which are presumed to be associated with interaction with its binding partner, kinesin family member 1C. Thus, these data suggest that the FERM domain of PTPN21 serves as a module that mediates protein-protein interaction, like other FERM domains.

Exploring heterogeneous expression of beta-actin (ACTB) in bladder cancer by producing a monoclonal antibody 6D6

BackgroundTo predict outcomes and identify potential therapeutic targets for cancers, it is critical to find novel specific biomarkers. The objective of this study was to search for and explore novel bladder cancer-associated protein biomarkers.MethodsA library of monoclonal antibodies (mAbs) against the JAM-ICR cell line was first generated, and clones with high affinity were selected. Hybridomas were screened using bladder cancer (BLCA) cell lines and normal cells. The target of the selected mAb was then characterized through immunoaffinity purification, western blotting, and mass spectrometry analysis. Expression of the target antigen was assessed by flow cytometry and IHC methods. Several databases were also used to evaluate the target antigen in BLCA and other types of cancers.ResultsBased on screenings, a 6D6 clone was selected that recognized an isoform of beta-actin (ACTB). Our data showed that ACTB expression on different cell lines was heterogeneous and varied significantly from low to high intensity. 6D6 bound strongly to epithelial cells while showing weak to no reactivity to stromal, endothelial, and smooth muscle cells. There was no association between ACTB intensity and related prognostic factors in BLCA. In silico evaluations revealed a significant correlation between ACTB and overexpressed genes and biomarkers in BLCA. Additionally, the differential expression of ACTB in tumor and healthy tissue as well as its correlation with survival time in a number of cancers were shown.ConclusionsThe heterogeneous expression of ACTB may suggest the potential value of this marker in the diagnosis or prognosis of cancer.

Molecular Docking and Dynamics Simulation study for Anticancer Phytoconstituents inhibiting breast cancer

The main challenge in the fight against breast cancer (BC) is to create new medications that are more selective for cancer cells and have fewer adverse effects. SPDEF (Sam pointed domain containing ETS transcription factor) is a prostate-derived ETS factor that maintains homeostasis, differentiation of epithelial tissues and heritable alterations in cancer. Previously, SPDEF has been shown to be associated with BC subtypes and is found to be down-regulated in invasive breast cancer cell lines which is supportive of its role in tumor suppression. In the current study, SPDEF protein was used as a potential breast cancer therapeutic target. A total of fifteen phytoconstituents were evaluated as potential drug ligands against SPDEF using various in silico approaches. Genistein, allicin, 2-hydroxychalcone and ajoene were free from any of the predicted toxicological endpoints. As per toxicological endpoints prediction study, the median lethal dosage (LD50) values for these phytoconstituents varied from 159 to 3919 mg/Kg. Our results indicate that out of fifteen, three phytoconstituents silibinin (-7.7 kcal/mol), codonolactone (-6.1 kcal/mol) and genistein (-6.1 kcal/mol), showing the lowest binding energies, had more significant inhibitory effects against SPDEF protein. We selected these three phytoconstituents on the basis of binding scores for molecular dynamic simulations at 200 ns to study their protein-ligand complex stability. Out of the three, silibinin-receptor complex had more stability. The present analysis shows that silibinin could be a potential therapeutic compound against breast cancer as assessed by its binding interaction and stability analyses against SPDEF.

Cell division cyclin 25C knockdown inhibits hepatocellular carcinoma development by inducing endoplasmic reticulum stress.

Cell division cyclin 25C (CDC25C) is a protein that plays a critical role in the cell cycle, specifically in the transition from the G2 phase to the M phase. Recent research has shown that CDC25C could be a potential therapeutic target for cancers, particularly for hepatocellular carcinoma (HCC). However, the specific regulatory mechanisms underlying the role of CDC25C in HCC tumorigenesis and development remain incompletely understood. To explore the impact of CDC25C on cell proliferation and apoptosis, as well as its regulatory mechanisms in HCC development. Hepa1-6 and B16 cells were transduced with a lentiviral vector containing shRNA interference sequences (LV-CDC25C shRNA) to knock down CDC25C. Subsequently, a xenograft mouse model was established by subcutaneously injecting transduced Hepa1-6 cells into C57BL/6 mice to assess the effects of CDC25C knockdown on HCC development in vivo. Cell proliferation and migration were evaluated using a Cell Counting Kit-8 cell proliferation assays and wound healing assays, respectively. The expression of endoplasmic reticulum (ER) stress-related molecules (glucose-regulated protein 78, X-box binding protein-1, and C/EBP homologous protein) was measured in both cells and subcutaneous xenografts using quantitative real-time PCR (qRT-PCR) and western blotting. Additionally, apoptosis was investigated using flow cytometry, qRT-PCR, and western blotting. CDC25C was stably suppressed in Hepa1-6 and B16 cells through LV-CDC25C shRNA transduction. A xenograft model with CDC25C knockdown was successfully established and that downregulation of CDC25C expression significantly inhibited HCC growth in mice. CDC25C knockdown not only inhibited cell proliferation and migration but also significantly increased the ER stress response, ultimately promoting ER stress-induced apoptosis in HCC cells. The regulatory mechanism of CDC25C in HCC development may involve the activation of ER stress and the ER stress-induced apoptosis signaling pathway.

The mechanism of USP43 in the development of tumor: a literature review.

Ubiquitination of the proteins is crucial for governing protein degradation and regulating fundamental cellular processes. Deubiquitinases (DUBs) have emerged as significant regulators of multiple pathways associated with cancer and other diseases, owing to their capacity to remove ubiquitin from target substrates and modulate signaling. Consequently, they represent potential therapeutic targets for cancer and other life-threatening conditions. USP43 belongs to the DUBs family involved in cancer development and progression. This review aims to provide a comprehensive overview of the existing scientific evidence implicating USP43 in cancer development. Additionally, it will investigate potential small-molecule inhibitors that target DUBs that may have the capability to function as anti-cancer medicines.

A single-cell strategy for the identification of intronic variants related to mis-splicing in pancreatic cancer.

Most clinical diagnostic and genomic research setups focus almost exclusively on coding regions and essential splice sites, thereby overlooking other non-coding variants. As a result, intronic variants that can promote mis-splicing events across a range of diseases, including cancer, are yet to be systematically investigated. Such investigations would require both genomic and transcriptomic data, but there currently exist very few datasets that satisfy these requirements. We address this by developing a single-nucleus full-length RNA-sequencing approach that allows for the detection of potentially pathogenic intronic variants. We exemplify the potency of our approach by applying pancreatic cancer tumor and tumor-derived specimens and linking intronic variants to splicing dysregulation. We specifically find that prominent intron retention and pseudo-exon activation events are shared by the tumors and affect genes encoding key transcriptional regulators. Our work paves the way for the assessment and exploitation of intronic mutations as powerful prognostic markers and potential therapeutic targets in cancer.

Comprehensive pan-cancer analysis: essential role of ABCB family genes in cancer.

The adenosine triphosphate-binding-cassette (ABC) transporter orchestrates the transmembrane transport of diverse substrates with the aid of ATP as an energy source. ABC transporter constitutes a widespread superfamily of transporters prominently present on the cellular membrane of organisms. Advancements in understanding have unveiled additional roles beyond mere intracellular or extracellular transport functions for the ABC protein family, encompassing involvement in DNA repair, protein translation, and gene expression regulation. Yet its role in tumors is still unknown. This study drew support from multiple databases, including Gene Expression Omnibus (GEO), European Genome-phenome Archive (EGA), The Cancer Genome Atlas (TCGA), and employed multidimensional bioinformatics analyses, incorporating online databases and the R-project. Through a comprehensive analysis, we seek to discern transcriptional-level disparities among genes and their consequential impacts on prognosis, tumor microenvironment (TME), stemness score, immune subtypes, clinical characteristics, and drug sensitivity across human cancers. ABC transporter subfamily B (ABCB) family genes exhibited heightened expression across diverse tumors, demonstrating a significant correlation with overall prognosis in pan-cancer contexts. Notably, gene expression levels manifested substantial associations with TME, stemness score, immune subtypes, clinical characteristics, and drug sensitivity in specific cancers, including kidney renal papillary cell carcinoma (KIRP), liver hepatocellular carcinoma (LIHC), and pancreatic adenocarcinoma (PAAD). Within this subset, transporter associated with antigen processing 1 (TAP1), TAP2, and ABCB6 emerged as noteworthy oncogenes. The outcomes of this study contribute to a comprehensive understanding of the implications of ABCB family genes in tumor progression, offering insights into potential therapeutic targets for cancer. Notably, the identification of ABCB6 as a significant oncogene suggests promising avenues for targeted therapies in KIRP, LIHC, and PAAD.

CK2 Inhibitors Targeting Inside and Outside the Catalytic Box

CK2 is a protein kinase that plays an important role in numerous cellular pathways involved in cell growth, differentiation, proliferation, and death. Consequently, upregulation of CK2 is implicated in many disease types, in particular cancer. As such, CK2 has gained significant attention as a potential therapeutic target in cancer, and over 40 chemical probes targeting CK2 have been developed in the past decade. In this review, we highlighted several chemical probes that target sites outside the conventional ATP-binding site. These chemical probes belong to different classes of molecules, from small molecules to peptides, and possess different mechanisms of action. Many of the chemical probes discussed in this review could serve as promising new candidates for drugs selectively targeting CK2.

Abstract 1670: Mechanistic insight into mTOR signaling identifies RNA splicing machinery as a potential therapeutic target for cancer

Abstract Aberrant signal transduction regulating cell growth and proliferation is a hallmark of many cancers. Activation of mTOR signaling is common and is an attractive therapeutic target with mechanistically different mTOR inhibitors in clinical use. One consequence of exposure to the mTOR inhibitor rapamycin is an alteration of gene expression through a global increase in alternative exon inclusion (Cheng et al. 2022, doi.org/10.3390/ijms232012416). To examine the mechanisms underlying this effect, we utilized the TempO-Seq targeted sequencing platform to profile both the whole transcriptome and a selection of alternatively spliced RNA targets in the rapamycin sensitive and resistant breast cancer cell lines MCF-7 and MDA MB 231 following exposure to 13 mTOR inhibitors, some closely related and some from distinct chemical classes. Recent publications have demonstrated that high quality dose response data can be obtained using this sequencing platform (Harrill et al. 2021, doi: 10.1093/toxsci/kfab009; Ramaiahgari et al. 2019, doi: 10.1093/toxsci/kfz065) and TempO-Seq has been widely adopted in toxicology for deriving compound-specific expression signatures to identify mechanisms of action and long-term toxicity. Treated cells were also profiled using TempO-LINC, a novel high-throughput single-cell assay based on the same platform. We observed that certain mTOR inhibitors induced both common and cell-specific differential expression as well as widespread alternative exon inclusion, as expected. Intriguingly, transcripts with the most significant changes in splicing upon treatment were those encoding members of the SR family of splicing factors, often overexpressed or amplified in breast cancers (Park, et al. 2019, doi: 10.1016/j.celrep.2019.10.110). This is significant because SR protein expression is autoregulated by alternative inclusion of an exon containing a premature stop codon in a feedback loop leading to nonsense-mediated decay (NMD) and lowered protein levels. Indeed, NMD is known to be inhibited by rapamycin (Martinez-Nunez, et al. 2017, doi: 10.1093/nar/gkw1109), which would lead to the observed accumulation of these transcripts. Thus, monitoring a targeted selection of alternative splicing events and regulators revealed mTOR regulation of mRNA isoform abundance consistent with regulation of the NMD RNA turnover process and with overexpression of SR proteins in breast cancers. Importantly, targeted bulk and single-cell TempO-Seq assays enable efficient sequencing and simplified data analysis without the expense and bioinformatic burden of RNAseq, making them particularly well-suited for drug discovery. These results support the use of this approach for further characterization of cell-specific effects of mTOR inhibitors and their mechanisms of action. Citation Format: Gaelle Rondeau, Megan Opichka, Kevin White, Joanne M. Yeakley, Dennis J. Eastburn, Bruce Seligmann. Mechanistic insight into mTOR signaling identifies RNA splicing machinery as a potential therapeutic target for cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1670.

CBP/p300 Degrader: A Promising Therapeutic Strategy for Treatment of Prostate Cancer and Beyond.

Transcriptional coactivators CBP/p300 have emerged as potential targets for cancer therapeutics. This Viewpoint discusses recent results that demonstrate an exceptionally potent and orally efficacious CBP/p300 degrader for the treatment of prostate cancer. This degrader stands out as a promising new candidate for cancer therapy and deserves further research.

Abstract 5604: Modulating DNA repair through endo-exonuclease inhibition: a new therapeutic paradigm in oncology

Abstract DNA damage repair (DDR) mechanisms are crucial for the maintenance of genomic stability and are emerging as potential therapeutic targets for cancer. Endo-exonuclease (EE)1 plays a key role in this process and increase EE expression has been observed in the cancer cells examined. In this context, we identified a dicationic diarylfuran, pentamidine, which is an antiparasitic drug that has been used clinically to treat opportunistic infections such as Pneumocystis carinii. Pentamidine is an inhibitor of the endo-exonuclease as determined by enzyme kinetic assay and is known to be active on cancer cells. In a proof of concept study2, tumor with increased EE expression (determined by IHC) showed the best response to this drug. We have now identified novel mono- and di-amidine analogs of pentamidine that are more effective than the parent drug in both in vitro and in vivo studies. Furthermore, pre-clinical animal studies of our lead candidate, MTDX203, showed an increased anti-cancer activity with a higher safety index than pentamidine. Based on a predictive PK/PD model, a human iv infusion dose administered twice weekly at ~0.4 mpk (i.e. 28 mg/day, ~10% of pentamidine effective iv dose) is expected to be clinically effective. Our work establishes the EE as a therapeutic target for cancer and identifies a new First in Class of novel anti-cancer agents. 1Chow et al. (2004) MCT 3:911-9182 NCT01378143: Pentamidine (OCZ103-OS) in Patients With Unresectable and Locally Recurrent or Metastatic Colorectal Cancer Undergoing Standard Chemotherap Citation Format: Terry Chow, Jianmin Duan, Patrick Colin, Colin Bier. Modulating DNA repair through endo-exonuclease inhibition: a new therapeutic paradigm in oncology [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5604.

Abstract 1651: Targeting intermediates of the PRMT5/BRG1 axis as a combination therapy

Abstract Over 40% of colorectal cancer (CRC) patients harbor a mutation in the KRAS gene, leading to a worse prognosis. PRMT5 and BRG1 are proteins considered potential therapeutic targets for cancer. Our lab has previously reported that both PRMT5 and BRG1 are overexpressed in KRAS mutant CRC when compared to KRAS wild-type CRC. It is therefore proposed that the PRMT5-BRG1 axis may be a strong therapeutic target for CRC. In this study, several key proteins that potentially mediate crosstalk between the PRMT5-BRG1 axis and KRAS were investigated.A literature review was first conducted to determine how the PRMT5-BRG1 axis acts in cancers. Additionally, pathways that may be involved in mediating the potential crosstalk between BRG1 and KRAS were discussed. Initial findings indicated that the PRMT5-BRG1 axis facilitates cancer oncogenesis. At the same time, the axis suppresses Myc/Max/Mad expression, leading to a dual role of the PRMT5-BRG1 axis depending on the tumor status. BRG1 was also found to work alongside mutant KRAS to affect tumor levels, with the effect differing by tumor type. The STRING database to determine the connection between the PRMT5-BRG1 axis and KRAS. It was determined that PRMT5, BRG1, and KRAS all interact with PBRM1, SMARCB1, ARID1A, and ARID2, with a combined interaction score &amp;gt;0.5. The UCSC Xena software was then used to analyze the mRNA data of CRC patients from The Cancer Genome Atlas (TCGA) database. Xena was utilized to determine which proteins are over expressed in CRC patient tumor samples compared to non-cancerous colon and rectum patient samples. Levels of PBRM1 and ARID1A were observed to significantly decrease in CRC patients as compared to non-cancerous samples by approximately 15% (adjp &amp;lt; 0.0001 and 0.05, respectively). However, SMARCB1 expression increased by 12% (adjp &amp;lt; 0.05). The Gene Expression Profiling Interactive Analysis (GEPIA) software was then used to analyze the correlation between the intermediary genes and PRMT5, BRG1, and KRAS in CRC patient tumor samples. PBRM1, SMARCB1, ARID1A, and ARID2 all demonstrated positive correlation with PRMT5, SMARCA4, and KRAS (R greater than 0.75 for nearly all correlations and p =0) in CRC patient tumor samples. Our study thus showcases the possible disrepair of the PRMT5/BRG1 axis in relation to KRAS. Key downstream proteins are decreased in CRC and may lower the potential crosstalk between PRMT5, BRG1, and KRAS. These findings are significant, and these key intermediate proteins may be strong therapeutic targets via inducing expression. Further research is currently in progress to outline the molecular processes behind the therapeutic role of revitalizing the SMARCA4/BRG1 axis when the downstream proteins are induced. Citation Format: Aaron Shaykevich, Isaac Silverman, Alexander Siegman, Radhashree Maitra. Targeting intermediates of the PRMT5/BRG1 axis as a combination therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1651.

Abstract 4730: Pharmacodynamic determinants of anti tumor activity of SHMT2 inhibitors

Abstract These studies investigate factors that impact the antitumor activity of SHMT2 targeting including drug accumulation, metabolism, expression of one carbon (C1) related enzymes, and tumor hypoxia. Mitochondrial C1 metabolism is upregulated in a variety of cancer types including leukemias and solid tumors. The mitochondrial C1 enzymes serine hydroxymethyltransferase (SHMT) 2 and 5,10-methylene tetrahydrofolate (THF) dehydrogenase 2 (MTHFD2) are among the top 5 overexpressed metabolic enzymes in tumors vs normal tissues in a wide range of tumor types. Thus, SHMT2 and MTHFD2 are potential therapeutic targets for cancer, sparing normal tissues that are less reliant on mitochondrial C1 metabolism. SHMT2 metabolizes serine and THF to produce glycine and 5,10-methylene THF; MTHFD2 metabolizes 5,10-methylene THF to NADH and 10-formyl THF which is converted to formate by MTHFD1L. Thus, mitochondrial C1 metabolism is the principal source of C1 units for cellular biosynthesis and provides the majority of glycine for protein, purine and glutathione synthesis. We previously discovered novel 5-substituted pyrrolo[3,2-d]pyrimidine antifolate compounds which exhibit primary inhibition at mitochondrial SHMT2 along with cytosolic SHMT1 and de novo purine biosynthesis at glycinamide ribonucleotide and 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferases. The lead compound AGF347 is taken up into cells by the facilitative transporters reduced folate carrier (SLC19A1) and the proton coupled folate transporter (SLC46A1) and like folate cofactors is metabolized to polyglutamate (PG) forms by folylpolyglutamate synthase (FPGS) which promotes retention in cytosolic and mitochondrial compartments and target enzyme engagement. We investigated the impact of folate transporter expression on metabolism to PGs for SHMT2 targeted antifolates. Folate transporter expression inversely correlated with anti-tumor efficacy of SHMT2 targeted antifolates and overexpression of FPGS resulted in dramatically increased sensitivities. However, for pyrazolopyran inhibitors of SHMT2 (e.g. SHIN1) which enter cells by diffusion and are not metabolized to polyglutamates, increased transporter and FPGS levels dramatically decreased anti-tumor activity. As SHMT2 is a target of HIF1α, we studied the impact of multitargeting SHMT2 and purine biosynthesis by pyrrolo[3,2-d]pyrimidine antifolates under hypoxic conditions. Our results establish that multi-targeting SHMT2 and purine biosynthesis preserves anti-tumor activity under hypoxia. Collectively, our results demonstrate that SHMT2 targeted pyrrolo[3,2-d]pyrimidine antifolates exhibit increased antitumor efficacies in cells expressing low folate transporter expression and is further enhanced by increased FPGS activity. Additionally, we find multitargeting of SHMT2 and de novo purine biosynthesis manifests as antitumor activity even under hypoxic conditions. Citation Format: Mathew Joseph Schneider, Carrie O'Connor, Xun Bao, Md. Junayed Nayeen, Zhanjun Hou, Jing Li, Aleem Gangjee, Larry Matherly. Pharmacodynamic determinants of anti tumor activity of SHMT2 inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4730.

Abstract 2375: 23ME-01473, a novel anti-ULBP6/2/5 monoclonal antibody, reinvigorates anti-tumor NK cell function through NKG2D and FcγRIIIa activation

Abstract Using genome-wide association studies (GWAS) of the 23andMe genetic and healthy survey database across all phenotypes as part of our unique target discovery platform, we identified immuno-oncology (I/O)-related genetic variants as those with opposing directionality of effects on cancer and immunological phenotypes, which comprise the I/O signature. This I/O signature identified ULBP6 as a potential cancer therapeutic target. ULBP6 is a stress-induced cell surface ligand found on cancer cells, that binds to the activating receptor, NKG2D, on NK and T cells to induce tumor cell killing. However, as a mechanism of immune escape, tumors shed ULBP6 to produce a soluble form that attenuates NKG2D activation and is elevated in cancers. Given that the 2 allelic variants of ULBP6 have the highest binding affinity to NKG2D of all human NKG2D ligands, ULBP6 may be the most immunosuppressive soluble NKG2D ligand and a critical regulator of anti-tumor response. Accordingly, soluble ULBP6 exhibited significant suppression of IFNγ release and detectable cell surface NKG2D expression on healthy donor PBMCs using in vitro cell-based assays. Moreover, the overexpression of human ULBP6 in a genetically modified MC38 murine model resulted in decreased infiltration of NK, NKT, and CD8 T cells in vivo. As such, we developed a novel humanized monoclonal antibody, 23ME-01473, that binds with high affinity to ULBP6, and due to the high sequence homology, to ULBP2 and ULBP5, to block their interaction with NKG2D. By preventing the binding of soluble ULBP6 to NKG2D on PBMCs in vitro, 23ME-01473 restored NKG2D activation as measured by increased detectable cell surface NKG2D expression, IFNγ and granzyme B release, and tumor cell killing by PBMCs. To further leverage the binding of 23ME-01473 to ULBP6/2/5, 23ME-01473 was designed to have an afucosylated Fc domain that enhances its binding affinity to the activating Fc receptor, FcγRIIIa, on NK cells to induce ADCC against tumor cells. The combination of NKG2D and FcγRIIIa activation resulted in synergistic PBMC-mediated IFNγ secretion and enhanced tumor cell killing, compared to activation of either NKG2D or FcγRIIIa. Taken together, these results reveal ULBP6 as a novel cancer therapeutic target, and given the dual activation of NKG2D and FcγRIIIa, suggest the potential of 23ME-01473 to activate NK cells and elicit anti-tumor immunity. Citation Format: Joel Benjamin, Abigail Jarret, Shashank Bharill, Shruti Yadav, Dina Ayupova, Clifford Hom, Zahra Bahrami Dizicheh, I-Ling Chen, Anh Diep, Shi Shi, Caroline Bonnans, Danielle Kellar, Germaine Fuh, Maike Schmidt, Kimberline Gerrick, Patrick Koenig, Mauro Poggio. 23ME-01473, a novel anti-ULBP6/2/5 monoclonal antibody, reinvigorates anti-tumor NK cell function through NKG2D and FcγRIIIa activation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2375.

Abstract 4695: Effect of fully human anti-PTGFRN antibody drug conjugate on head neck cancer cells and patient derived xenografts

Abstract Prostaglandin F2 Receptor Negative regulator, or PTGFRN, also known as FPRP is a 175 kDa transmembrane protein associated with metastatic characteristics of certain cancer types and a member of the tetraspanin family. PTGFRN expression is undetectable to low in normal tissues whereas it is elevated in several cancers such as head and neck, mesothelioma and medulloblastoma. PTGFRN has also been reported to be upregulated in many different types of cancer, increasingly so in metastatic cancer cells, compared to their non-metastatic counterparts PTGFRN expression has been reported to be a poor prognostic factor for glioblastoma making it a potential novel cancer therapeutic target. We have previously shown that PTGFRN is an internalizable cell surface protein making it suitable for targeting by antibody drug conjugate (ADC). We have developed fully human monoclonal antibodies to PTGFRN by immunizing humanized transgenic TC mice with human PTGFRN. Within 60 days from the start of immunization we were able to select several fully human anti-PTGFRN monoclonal antibodies that were examined by several functional assays that included flow binding, internalization, affinity determination and cell killing as antibody drug conjugates. Several monoclonal antibodies were selected and evaluated for their ability to inhibit tumor formation in several cancers. Selected antibodies were then conjugated to duocarmycin by a cleavable linker. The present study proposed to examine the effect of one such anti-PTGFRN ADC on head and neck cancer cell lines and patient derived xenografts that had been analyzed for their PTGFRN expression by western blot analysis using anti-PTGFRN antibody. Cells lines and PDX that were positive for PTGFRN expression were used to examine the effect of anti-PTGFRN ADC on their in vitro and in vivo proliferation. The data show that anti-PTGFRN ADC inhibits tumor formation in a dose-dependent fashion. These data also establish PTGFRN as cancer druggable target and the selected fully human anti-PTGFRN antibody as an attractive antibody for the development of new antibody drug conjugate in Oncology. These data also emphasize the potential of humanized transgenic TC mice for the development of fully human monoclonal antibodies, thus bypassing the need for humanization and affinity maturation required by other humanized mice or phase display. Citation Format: Jorge Marquez, Jianping Dong, Mitsuo Oshimura, Jun Hayashi, Ginette Serrero. Effect of fully human anti-PTGFRN antibody drug conjugate on head neck cancer cells and patient derived xenografts [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4695.

Biological role and regulation of circular RNA as an emerging biomarker and potential therapeutic target for cancer.

Circular RNAs (circRNAs) are a unique family of endogenous RNAs devoid of 3' poly-A tails and 5' end caps. These single-stranded circRNAs, found in the cytoplasm, are synthesized via back-splicing mechanisms, merging introns, exons, or both, resulting in covalently closed circular loops. They are profusely expressed across the eukaryotic transcriptome and offer heightened stability against exonuclease RNase R compared to linear RNA counterparts. This review endeavors to provide a comprehensive overview of circRNAs' characteristics, biogenesis, and mechanisms of action. Furthermore, aimed to shed light on the potential of circRNAs as significant biomarkers in various cancer types. It has been performed an exhaustive literature review, drawing on recent studies and findings related to circRNA characteristics, synthesis, function, evaluation techniques, and their associations with oncogenesis. CircRNAs are intricately associated with tumor progression and development. Their multifaceted roles encompass gene regulation through the sponging of proteins and microRNAs, controlling transcription and splicing, interacting with RNA binding proteins (RBPs), and facilitating gene translation. Due to these varied roles, circRNAs have become a focal point in tumor pathology investigations, given their promising potential as both biomarkers and therapeutic agents. CircRNAs, due to their unique biogenesis and multifunctionality, hold immense promise in the realm of oncology. Their stability, widespread expression, and intricate involvement in gene regulation underscore their prospective utility as reliable biomarkers and therapeutic targets in cancer. As our understanding of circRNAs deepens, advanced techniques for their detection, evaluation, and manipulation will likely emerge. These advancements might catalyze the translation of circRNA-based diagnostics and therapeutics into clinical practice, potentially revolutionizing cancer care and prognosis.

FPFT-2216, a Novel Anti-lymphoma Compound, Induces Simultaneous Degradation of IKZF1/3 and CK1α to Activate p53 and Inhibit NFκB Signaling.

We found potential vulnerability to CK1α degradation in certain lymphoma cells refractory to IKZF1/3 degraders. Targeting CK1α with FPFT-2216 could inhibit the growth of these cells by activating p53 signaling. Our study demonstrates the potential therapeutic application of CK1α degraders, such as FPFT-2216, for treating lymphoma.

Transmembrane pH gradient imaging in rodent glioma models.

A unique feature of the tumor microenvironment is extracellular acidosis in relation to intracellular milieu. Metabolic reprogramming in tumors results in overproduction of H+ ions (and lactate), which are extruded from the cells to support tumor survival and progression. As a result, the transmembrane pH gradient (ΔpH), representing the difference between intracellular pH (pHi) and extracellular pH (pHe), is posited to be larger in tumors compared with normal tissue. Controlling the transmembrane pH difference has promise as a potential therapeutic target in cancer as it plays an important role in regulating drug delivery into cells. The current study shows successful development of an MRI/MRSI-based technique that provides ΔpH imaging at submillimeter resolution. We applied this technique to image ΔpH in rat brains with RG2 and U87 gliomas, as well as in mouse brains with GL261 gliomas. pHi was measured with Amine and Amide Concentration-Independent Detection (AACID), while pHe was measured with Biosensor Imaging of Redundant Deviation in Shifts (BIRDS). The results indicate that pHi was slightly higher in tumors (7.40-7.43 in rats, 7.39-7.47 in mice) compared with normal brain (7.30-7.38 in rats, 7.32-7.36 in mice), while pHe was significantly lower in tumors (6.62-6.76 in rats, 6.74-6.84 in mice) compared with normal tissue (7.17-7.22 in rats, 7.20-7.21 in mice). As a result, ΔpH was higher in tumors (0.64-0.81 in rats, 0.62-0.65 in mice) compared with normal brain (0.13-0.16 in rats, 0.13-0.16 in mice). This work establishes an MRI/MRSI-based platform for ΔpH imaging at submillimeter resolution in gliomas.