Abstract This abstract is being presented as a short talk in the scientific program. A full abstract is printed in the Proffered Abstracts section (PR004) of the Conference Program/Proceedings. Citation Format: Yuxia Zhang, Virginia Ojeda, Xiaobo Wang, Ken Dunner, Filippo Giancotti, Hao Zhou, Jonathan Hernandez, Steven Q. Xu. Merlin/NF2 inhibits pancreatic cancer metastasis by activation of AMPK-dependent autophagic degradation of p62 [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr A029.

A new route to benzyl thioether derivatives has been developed via the N-heterocyclic carbene palladium(II)-catalyzed cross coupling of benzylammonium salts with thiophenols. Under the optimal conditions, different benzylammonium salts could be well tolerated. Meanwhile, various kinds of aryl thiophenols and heteroaryl thiophenols could be used as efficient substrates, generating broad array of benzyl thioethers in good to high yields within hours.

Background: Systemic factors from the tumor microenvironment (TME) promote prostate cancer (PCa) progression, metastasis, and drug resistance. Therefore, the identification of the systemic factors that can modulate the tumor cells and promote metastases will be critical to improve the efficacy of clinical treatment. Both mechanistic and functional studies revealed that acquisition of an open chromatin state on master regulators or cis-regulatory elements allow them to respond readily to microenvironment signals, thereby increasing cancer cell plasticity, tumorigenicity and malignant potential. Accordingly, analysis of open chromatin regions can help prioritize and identify risk of functionally noncoding variants. Given the power of open chromatin profiling on environmental risk prediction, we hypothesized that analysis of open chromatin regions may enable us to recognize functional trans-regulatory elements with their relevant systemic factors. Methods and Results: In human prostate cancer cells, AR blockage by enzalutamide can induces cell reprogramming, as well as transcriptional dysregulation of the heterochromatin compaction pathway. Hence, we proposed that the cells were undergoing chromatin decondensation followed by epigenetic reprogramming. To detect the genome-wide open chromatin changes in this process, we performed time course ATAC-seq and H3K27ac ChIP-seq experiments on LNCaP cells treated with enzalutamide over a 2 weeks period. Bioinformatic analysis was performed to identify the “open” enhancers and the transcriptional factors potentially bound to these enhancers. Integrated transcription factor binding motif analysis of metastatic castration-resistant prostate cancer (mCRPC) associated enhancer regions (GSE130408) and multiplexed siRNA screening revealed Thyroid Hormone Receptor Beta (THRB) as the top candidate. THRB is regulated by the thyroid hormone (T3), a systemic nuclear hormone that, in enzalutamide pretreated LNCaP, VCaP and 3PDXs, is able to induce subsequent reprogramming to a fully enzalutamide-resistant and metastatic state. Interestingly, we observed that THRB regulated genes are upregulated in T3-induced resistant prostate cancer cells. Consistently, the THRB protein, TRβ, is abundant in several aggressive PCa cell lines. Notably, knockdown of THRB reverted the growth and the bone metastatic potential of highly aggressive PCa models, such as Ptenpc-/-Smad4pc-/- and PC3M cells. Furthermore, both transcriptomic and functional analyses identified RUNX2 as a transcriptional target of THRB. In summary, we identify a novel mechanism of THRB-mediated tumor progression and drug resistance in PCa cells. Conclusion: Epidemiologic evidence indicates a higher incidence of PCa in men with elevated thyroid hormone levels. Accordingly, our results suggest a new mechanism for thyroid hormone signaling regulating metastasis potential and drug resistance. This study will provide a new perspective to identify the signals from the TME that may increase the risk of PCa progression. Citation Format: Yan Wang, Gurrapu Harsha, Dhiraj Kumar, Josue Curto, Xiaobo Wang, Filippo Giancotti. Thyroid hormone receptor signaling promotes antiandrogen resistance and bone metastasis in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr LB023.

We have examined the mechanism through which fibrotic extracellular matrices promote tumor progression and metastasis in HER2+ breast cancer. We found that integrin-mediated mechano-transduction and engagement of ERBB2/ERBB3 cooperate to induce activation of YAP and invasive growth in stiff 3D Matrigel-Collagen I. Mechanistic studies revealed that joint activation of SRC Family Kinases (SFKs) by FAK and ERBB2/3 results in tyrosine phosphorylation and inactivation of LATS1/2 and MOB1. The ensuing activation of YAP enables HER2+ breast cancer cells to proliferate and invade in 3D Matrigel-Collagen I. In addition, tyrosine phosphorylation of LATS1/2 and MOB1 and activation of YAP are required for v-SRC-mediated transformation of fibroblasts. Finally, preclinical studies indicated that FAK-SRC signaling is required for primary tumor growth and lung metastasis in the MMTV- Neu mouse model of HER2+ breast cancer. Congruently, administration of dasatinib significantly increased the capacity of lapatinib to inhibit primary tumor growth and lung colonization in MMTV- Ne u mice. These findings indicate that integrin-mediated mechano-transduction functions as a rheostat to regulate ERBB2 signaling to YAP and suggest that co-targeting ERBB2 and SFKs may exhibit therapeutic efficacy in HER2+ breast cancer. Significance statement Stromal stiffness, which ensues from increased deposition and crosslinking of linear collagens, promotes oncogenesis and tumor progression in the breast. Moreover, tumor fibrosis is increased in the more aggressive subtypes of breast cancer, such as Triple Negative (TN) and HER2+ breast cancer. However, the mechanisms through which extracellular matrix stiffness regulates intracellular signaling are poorly understood. In this study, we show that the Focal Adhesion Kinase (FAK)-SRC Family Kinase (SFK) complex integrates the sensing of matrix rigidity by integrins and the activation of ERBB2/3 to promote activation of YAP and that YAP is required for breast cancer growth and invasion. Mechanistic studies demonstrate that SFKs can phosphorylate and inhibit LATS1 and MOB1, leading to activation of YAP. Simultaneous inhibition of ERBB2/3 with lapatinib and SFKs with dasatinib profoundly inhibits primary tumor growth and metastasis in a mouse model of HER2+ breast cancer. These findings suggest that the therapeutic efficacy of combinatorial blockade of ERBB2 and integrin-mediated mechano-transduction should be tested in biomarker-driven clinical trials.

Bioinformatic analysis of 94 patient-derived xenografts (PDXs), cell lines, and organoids (PCOs) identifies three intrinsic transcriptional subtypes of metastatic castration-resistant prostate cancer androgen receptor (AR) pathway + prostate cancer (PC) (ARPC), mesenchymal and stem-like PC (MSPC), and neuroendocrine PC (NEPC). A sizable proportion of castration-resistant and metastatic stage PC (M-CRPC) cases are admixtures of ARPC and MSPC. Analysis of clinical datasets and mechanistic studies indicates that MSPC arises from ARPC as a consequence of therapy-induced lineage plasticity. AR blockade with enzalutamide induces (1) transcriptional silencing of TP53 and hence dedifferentiation to a hybrid epithelial and mesenchymal and stem-like state and (2) inhibition of BMP signaling, which promotes resistance to AR inhibition. Enzalutamide-tolerant LNCaP cells re-enter the cell cycle in response to neuregulin and generate metastasis in mice. Combined inhibition of HER2/3 and AR or mTORC1 exhibits efficacy in models of ARPC and MSPC or MSPC, respectively. These results define MSPC, trace its origin to therapy-induced lineage plasticity, and reveal its sensitivity to HER2/3 inhibition.

Unsupervised clustering and deconvolution analysis identifies a novel subtype of M-CRPC endowed with hybrid epithelial/mesenchymal (E/M) and luminal progenitor-like traits (Mesenchymal and Stem-like PC, MSPC). Analysis of patient datasets and mechanistic studies indicate that MSPC arises as a consequence of therapy-induced lineage plasticity. AR blockade instigates two separate and complementary processes: 1) transcriptional silencing of TP53 and hence acquisition of hybrid E/M and stem-like traits; and 2) inhibition of the BMP signaling, which promotes resistance to the pro-apoptotic and anti-proliferative effects of AR inhibition. The drug-tolerant prostate cancer cells generated through reprogramming are rescued by neuregulin and generate metastases in mice. Combined inhibition of HER2/3 and AR or mTORC1 exhibit efficacy in preclinical models of mixed ARPC/MSPC or MSPC, respectively. These results identify a novel subtype of M-CRPC, trace its origin to therapy-induced lineage plasticity, and reveal its dependency on HER2/3 signaling.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Inhibiting glycolysis remains an aspirational approach for the treatment of cancer. We have previously identified a subset of cancers harbouring homozygous deletion of the glycolytic enzyme enolase (ENO1) that have exceptional sensitivity to inhibition of its redundant paralogue, ENO2, through a therapeutic strategy known as collateral lethality. Here, we show that a small-molecule enolase inhibitor, POMHEX, can selectively kill ENO1 -deleted glioma cells at low-nanomolar concentrations and eradicate intracranial orthotopic ENO1 -deleted tumours in mice at doses well-tolerated in non-human primates. Our data provide an in vivo proof of principle of the power of collateral lethality in precision oncology and demonstrate the utility of POMHEX for glycolysis inhibition with potential use across a range of therapeutic settings.

ABSTRACT Inhibiting glycolysis remains an aspirational approach for the treatment of cancer. We recently demonstrated that SF2312, a natural product phosphonate antibiotic, is a potent inhibitor of the glycolytic enzyme Enolase with potential utility for the collateral lethality-based treatment of Enolase-deficient glioblastoma (GBM). However, phosphonates are anionic at physiological pH, limiting cell and tissue permeability. Here, we show that addition of pivaloyloxymethyl (POM) groups to SF2312 (POMSF) dramatically increases potency, leading to inhibition of glycolysis and killing of ENO1 -deleted glioma cells in the low nM range. But the utility of POMSF in vivo is dose-limited by severe hemolytic anemia. A derivative, POMHEX, shows equipotency to POMSF without inducing hemolytic anemia. POMHEX can eradicate intracranial orthotopic ENO1 -deleted tumors, despite sub-optimal pharmacokinetic properties. Taken together, our data provide in vivo proof-of-principal for collateral lethality in precision oncology and showcase POMHEX as a useful molecule for the study of glycolysis in cancer metabolism.

Background: In children and adolescents, osteosarcomais the most common malignant bone tumor with a high mortality rate. New therapeutic strategies are urgent to be explored. Studies have proven that microRNAs (miRNAs) in malignant tumors often appear dysregulation, this provides a direction for exploring the new therapeutic strategies for cancers. The aim of this meta-analysis is to summarize and analyze whethermicroRNA-34a(miRNA-34a) could be a prognostic marker for osteosarcoma in mice. Methods: We searched PubMed, Web of Science, Embase, Wan Fang Database, China Knowledge Resource Integrated Database, VIP Database, and SinoMed since their initiation date to January 24, 2018. After screening based on inclusion and exclusion criteria, eight articles were included for the final analysis. Results: Our results showed that tumor volume and tumor weight were inhibited by restoring the down-regulated expression of miRNA-34a in the xenograft mouse models. Conclusions: Down-regulated miRNA-34a expression is a prognostic marker for poor osteosarcoma. We should be more committed to investigate the clinical significance of miRNA-34a in osteosarcoma patients.

Clear cell renal cell carcinoma (ccRCC) is the major subtype of renal cell carcinoma (RCC) that is resistant to conventional radiation and chemotherapy. It is a challenge to explore effective therapeutic targets and drugs for this kind of cancer. Transcription factor Krüppel-like factor 5 (KLF5) exerts diverse functions in various tumor types. By analyzing cohorts of the Cancer Genome Atlas (TCGA) data sets, we find that KLF5 expression is suppressed in ccRCC patients and higher level of KLF5 expression is associated with better prognostic outcome. Our further investigations demonstrate that KLF5 genomic loci are hypermethylated at proximal exon 4 and suppression of DNA methyltransferase 1 (DNMT1) expression by ShRNAs or a methylation inhibitor 5-Aza-CdR can recover KLF5 expression. Meanwhile, there is a negative correlation between expressions of KLF5 and DNMT1 in ccRCC tissues. Ectopic KLF5 expression inhibits ccRCC cell proliferation and migration/invasion in vitro and decreases xenograft growth and metastasis in vivo. Moreover, 5-Aza-CdR, a chemotherapy drug as DNMTs' inhibitor that can induce KLF5 expression, suppresses ccRCC cell growth, while knockdown of KLF5 abolishes 5-Aza-CdR-induced growth inhibition. Collectively, our data demonstrate that KLF5 inhibits ccRCC growth as a tumor suppressor and highlight the potential of 5-Aza-CdR to release KLF5 expression as a therapeutic modality for the treatment of ccRCC.

China accounts for almost half of the total number of liver cancer cases and deaths worldwide, and hepatocellular carcinoma (HCC) is the most primary liver cancer. Snail family transcriptional repressor 2 (SNAI2) is known as an epithelial to mesenchymal transition inducing transcription factor that drives neoplastic epithelial cells into mesenchymal phenotype. However, the roles of endogenous SNAI2 remain controversial in different types of malignant tumors. Herein, we surprisingly identify that anchorage-independent growth, including the formation of tumor sphere and soft agar colony, is significantly increased when SNAI2 expression is inhibited by shRNAs in HCC cells. Suppression of SNAI2 suffices to up-regulate several cancer stem genes. Although unrelated to the metastatic ability, SNAI2 inhibition does increase the efflux of Hoechst 33342 and enhance multidrug resistance in vitro and in vivo. In agreement with this data, we demonstrate for the first time that decreasing SNAI2 level can transcriptionally upregulate several ATP binding cassette (ABC) transporter genes such as ABCB1. Moreover, ABC transporters' inhibitor verapamil can rescue the multidrug resistance induced by SNAI2 inhibition. Our results implicate that SNAI2 behaves as a tumor suppressor by inhibiting multidrug resistance via suppressing ABC transporter genes in HCC cells.