The nuclear factor erythroid 2-related factor 2 (NRF2) pathway is frequently activated in various cancer types. Aberrant activation of NRF2 in cancer is attributed to gain-of-function mutations in the NRF2-encoding gene NFE2L2 or a loss of function of its suppressor, Kelch-like ECH-associated protein 1 (KEAP1). NRF2 activation exerts pro-tumoral effects in part by altering cancer cell metabolism. Previously, we reported a novel mechanism of NRF2 tumoral immune suppression through the selective upregulation of the tryptophan-metabolizing enzyme kynureninase (KYNU) in lung adenocarcinoma. In the current study, we explored the relevance of NRF2-mediated KYNU upregulation across multiple cancer types. Specifically, using a gene expression dataset for 9801 tumors representing 32 cancer types from The Cancer Genome Atlas (TCGA), we demonstrated that elevated KYNU parallels increased gene-based signatures of NRF2-activation and that elevated tumoral KYNU mRNA expression is strongly associated with an immunosuppressive tumor microenvironment, marked by high expression of gene-based signatures of Tregs as well as the immune checkpoint blockade-related genes CD274 (PDL-1), PDCD1 (PD-1), and CTLA4, regardless of the cancer type. Cox proportional hazard models further revealed that increased tumoral KYNU gene expression was prognostic for poor overall survival in several cancer types, including thymoma, acute myeloid leukemia, low-grade glioma, kidney renal papillary cell carcinoma, stomach adenocarcinoma, and pancreatic ductal adenocarcinoma (PDAC). Using PDAC as a model system, we confirmed that siRNA-mediated knockdown of NRF2 reduced KYNU mRNA expression, whereas activation of NFE2L2 (the coding gene for NRF2) through either small-molecule agonists or siRNA-mediated knockdown of KEAP1 upregulated KYNU in PDAC cells. Metabolomic analyses of the conditioned medium from PDAC cell lines revealed elevated levels of KYNU-derived anthranilate, confirming that KYNU was enzymatically functional. Collectively, our study highlights the activation of the NRF2–KYNU axis as a multi-cancer phenomenon and supports the relevance of tumoral KYNU as a marker of tumor immunosuppression and as a prognostic marker for poor overall survival.

Intra-tumoral expression of the serine hydrolase carboxylesterase 2 (CES2) contributes to the activation of the pro-drug irinotecan in pancreatic ductal adenocarcinoma (PDAC). Given other potential roles of CES2, we assessed its regulation, downstream effects, and contribution to tumor development in PDAC. Association between the mRNA expression of CES2 in pancreatic tumors and overall survival was assessed using The Cancer Genome Atlas. Cell viability, clonogenic, and anchorage-independent growth assays as well as an orthotopic mouse model of PDAC were used to evaluate the biological relevance of CES2 in pancreatic cancer. CES2-driven metabolic changes were determined by untargeted and targeted metabolomic analyses. Elevated tumoral CES2 mRNA expression was a statistically significant predictor of poor overall survival in PDAC patients. Knockdown of CES2 in PDAC cells reduced cell viability, clonogenic capacity, and anchorage-independent growth in vitro and attenuated tumor growth in an orthotopic mouse model of PDAC. Mechanistically, CES2 was found to promote the catabolism of phospholipids resulting in HNF4α activation through a soluble epoxide hydrolase (sEH)-dependent pathway. Targeting of CES2 via siRNA or small molecule inhibitors attenuated HNF4α protein expression and reduced gene expression of classical/progenitor markers and increased basal-like markers. Targeting of the CES2-sEH-HNF4α axis using small molecule inhibitors of CES2 or sEH reduced cell viability. We establish a novel regulatory loop between CES2 and HNF4α to sustain the progenitor subtype and promote PDAC progression and highlight the potential utility of CES2 or sEH inhibitors for the treatment of PDAC as part of non-irinotecan-containing regimens.

C-MYC and its paralogues MYCN and MYCL are among the most frequently amplified and/or overexpressed oncoproteins in ovarian cancer. c-MYC plays a key role in promoting ovarian cancer initiation and progression. The polyamine pathway is a bona fide target of c-MYC signaling, and polyamine metabolism is strongly intertwined with ovarian malignancy. Targeting of the polyamine pathway via small molecule inhibitors has garnered considerable attention as a therapeutic strategy for ovarian cancer. Herein, we discuss the involvement of c-MYC signaling and that of its paralogues in promoting ovarian cancer tumorigenesis. We highlight the potential of targeting c-MYC-driven polyamine metabolism for the treatment of ovarian cancers and the utility of polyamine signatures in biofluids for early detection applications.

Purpose: We conducted metabolomics and spatial cell transcriptomics of intraductal papillary mucinous neoplasms (IPMN), recognized pancreatic cancer precursors, to identify oncometabolites that inform upon risk of malignancy of IPMNs. Experimental Design: Untargeted metabolomic analyses were performed on cystic fluid from 125 patients with low-grade (LG) dysplasia or high-grade (HG) dysplasia with/without concurrent pancreatic ductal adenocarcinoma (PDAC; IPMN/PDAC). Predictive performance of individual metabolites for identifying HG or PDAC/IPMN was determined and compared with CA19-9 performance. Data were intersected with metabolic profiles of resected IPMN tissues and murine Kras;Gnas IPMN cell lines as well as spatial and single-cell transcriptomics of IPMNs. Results: A total of 388 metabolites were quantified in cystic fluid, of which 69 were differential (P-value < 0.05) between cases (HG IPMN + IPMN/PDAC) and patients with LG IPMN. Spermidine and spermine biosynthesis and catabolism was identified as the top perturbed metabolic pathway (FDR-adjusted P-value < 0.0001). Increases in cystic fluid spermidine, n-acetylputrescine, acetylspermidine, diacetylspermidine, diacetylspermine, and acetylcadaverine were associated elevated risk of harboring HG or IPMN/PDAC. An OR rule comprising CA19-9, n-acetylputrescine, acetylspermidine, and diacetylspermine achieved 54.8% sensitivity for detecting HG IPMN and IPMN\PDAC. CA19-9 alone yielded sensitivity of 11.9% (McNemar Test P-value < 0.001). Polyamines were elevated in IPMN\PDAC tissues compared with LG IPMN tissues; spatial and single-cell transcriptomic data revealed transcript levels of polyamine-metabolizing enzymes to be elevated in neoplastic epithelium and tumor-associated macrophages. Conclusions: Cystic fluid polyamines offer utility for determining risk of malignancy of IPMNs that is complementary to CA19-9 and that has potential to aid in clinical management of patients with IPMNs.

Treatment of lung adenocarcinomas (LUADs) that exhibit activated epidermal growth factor receptor (EGFR) with EGFR tyrosine kinase inhibitors (TKIs) has limited efficacy. Assessment of the impact of EGFR TKI on the LUAD surfaceome remodeling reveals potential therapeutic targets. We identify placental type alkaline phosphatase (ALPP), which has restricted expression in normal tissues, among upregulated surface proteins following EGFR TKI treatment of both TKI sensitive as well as resistant cells. EGF treatment represses ALPP expression, whereas EGFR TKIs upregulate its expression through dephosphorylation and activation of FoxO3a, a transcriptional regulator that binds to the promoter region of ALPP. The combination of EGFR TKI plus ALPP antibody conjugated with monomethyl auristatin F enhances tumor killing in osimertinib-sensitive and -resistant LUAD models compared to either treatment alone. Our findings support a combination therapy involving an EGFR inhibitor together with an ALPP antibody drug conjugate for EGFR-mutated LUADs.

Background/Objectives:Cancer vaccine targets mostly include mutations and overexpressed proteins. However, cancer-associated post-translational modifications (PTMs) may also induce immune responses. Previously, our group established the enzyme protein arginine deiminase type-2 (PADI2), which catalyzes citrullination modification, is highly expressed in triple-negative breast cancer (TNBC), promoting antigenicity. Methods: Here, we show the workflow of designing citrullinated enolase 1 (citENO1) vaccine peptides identified from breast cancer cells by mass spectrometry and demonstrate TNBC vaccine efficacy in the mouse model. Immunized mice with citENO1 peptides or the corresponding unmodified peptides, plus Poly I:C as an adjuvant, were orthotopically implanted with a TNBC murine cell line. Results: Vaccination with citENO1, but not unmodified ENO1 (umENO1), induced a greater percentage of activated CD8+ PD-1+ T cells and effector memory T cells in skin-draining lymph nodes (SDLNs). Remarkably, the citENO1 vaccine delayed tumor growth and prolonged overall survival, which was further enhanced by PD-1 blockade. Conclusions: Our data suggest that cancer-restricted post-translational modifications provide a source of vaccines that induce an anti-cancer immune response.