Genetic and pharmacologic abrogation of Snail1 inhibits acinar-to-ductal metaplasia in precursor lesions of pancreatic ductal adenocarcinoma and pancreatic injury

POH1 facilitates pancreatic carcinogenesis through MYC-driven acinar-to-ductal metaplasia and is a potential therapeutic target

Pancreatic acinar cells undergo acinar-to-ductal metaplasia (ADM), a necessary process for pancreatic ductal adenocarcinoma (PDAC) initiation. However, the regulatory role of POH1, a deubiquitinase linked to several types of cancer, in ADM and PDAC is unclear. In this study, we investigated the role of POH1 in ADM and PDAC using murine models. Our findings suggest that pancreatic-specific deletion of Poh1 alleles attenuates ADM and impairs pancreatic carcinogenesis, improving murine survival. Mechanistically, POH1 deubiquitinates and stabilizes the MYC protein, which potentiates ADM and PDAC. Furthermore, POH1 is highly expressed in PDAC samples, and clinical evidence establishes a positive correlation between aberrantly expressed POH1 and poor prognosis in PDAC patients. Targeting POH1 with a specific small-molecule inhibitor significantly reduces pancreatic tumor formation, highlighting POH1 as a promising therapeutic target for PDAC treatment. Overall, POH1-mediated MYC deubiquitination is crucial for ADM and PDAC onset, and targeting POH1 could be an effective strategy for PDAC treatment, offering new avenues for PDAC targeted therapy.

NFATc1 Is a Central Mediator of EGFR-Induced ARID1A Chromatin Dissociation During Acinar Cell Reprogramming

BACKGROUND & AIMS

Loss of AT-rich interactive domain-containing protein 1A (ARID1A) fosters acinar-to-ductal metaplasia (ADM) and pancreatic carcinogenesis by down-regulating transcription programs controlling acinar cell identity. However, how ARID1A reacts to metaplasia-triggering environmental cues remains elusive. Here, we aimed to elucidate the role of ARID1A in controlling ductal pancreatic gene signatures and deciphering hierarchical signaling cues determining ARID1A-dependent chromatin regulation during acinar cell reprogramming.

METHODS

Acinar cell explants with differential ARID1A status were subjected to genome-wide expression analyses. The impact of epidermal growth factor receptor (EGFR) signaling, NFATc1 activity, and ARID1A status on acinar reprogramming processes were characterized by ex vivo ADM assays and transgenic mouse models. EGFR-dependent ARID1A chromatin binding was studied by chromatin immunoprecipitation sequencing analysis and cellular fractionation.

RESULTS

EGFR signaling interferes with ARID1A-dependent transcription by inducing genome-wide ARID1A displacement, thereby phenocopying ARID1A loss-of-function mutations and inducing a shift toward ADM permissive ductal transcription programs. Moreover, we show that EGFR signaling is required to push ARID1A-deficient acinar cells toward a metaplastic phenotype. Mechanistically, we identified the transcription factor nuclear factor of activated T cells 1 (NFATc1) as the central regulatory hub mediating both EGFR signaling-induced genomic ARID1A displacement and the induction of ADM-promoting gene signatures in the absence of ARID1A. Consequently, pharmacologic inhibition of NFATc1 or its depletion in transgenic mice not only preserves genome-wide ARID1A occupancy, but also attenuates acinar metaplasia led by ARID1A loss.

CONCLUSIONS

Our data describe an intimate relationship between environmental signaling and chromatin remodeling in orchestrating cell fate decisions in the pancreas, and illustrate how ARID1A loss influences transcriptional regulation in acinar cell reprogramming.

Molecular signaling in pancreatic ductal metaplasia: emerging biomarkers for detection and intervention of early pancreatic cancer

Pancreatic ductal metaplasia (PDM) is the transformation of potentially various types of cells in the pancreas into ductal or ductal-like cells, which eventually replace the existing differentiated somatic cell type(s). PDM is usually triggered by and manifests its ability to adapt to environmental stimuli and genetic insults. The development of PDM to atypical hyperplasia or dysplasia is an important risk factor for pancreatic intraepithelial neoplasia (PanIN) and pancreatic ductal adenocarcinoma (PDA). Recent studies using genetically engineered mouse models, cell lineage tracing, single-cell sequencing and others have unraveled novel cellular and molecular insights in PDM formation and evolution. Those novel findings help better understand the cellular origins and functional significance of PDM and its regulation at cellular and molecular levels. Given that PDM represents the earliest pathological changes in PDA initiation and development, translational studies are beginning to define PDM-associated cell and molecular biomarkers that can be used to screen and detect early PDA and to enable its effective intervention, thereby truly and significantly reducing the dreadful mortality rate of PDA. This review will describe recent advances in the understanding of PDM biology with a focus on its underlying cellular and molecular mechanisms, and in biomarker discovery with clinical implications for the management of pancreatic regeneration and tumorigenesis.

Acinar to ductal cell trans-differentiation: A prelude to dysplasia and pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the deadliest neoplastic epithelial malignancies and is projected to be the second leading cause of cancer-related mortality by 2024. Five years overall survival being ~10%, mortality and incidence rates are disturbing. Acinar to ductal cell metaplasia (ADM) encompasses cellular reprogramming and phenotypic switch-over, making it a cardinal event in tumor initiation. Differential cues and varied regulatory factors drive synchronous functions of metaplastic cell populations leading to multiple cell fates and physiological outcomes. ADM is a precursor for developing early pre-neoplastic lesions further progressing into PC due to oncogenic signaling. Hence delineating molecular events guiding tumor initiation may provide cues for regenerative medicine and precision onco-medicine. Therefore, understanding PC pathogenesis and early diagnosis are crucial. We hereby provide a timely overview of the current progress in this direction and future perspectives we foresee unfolding in the best interest of patient well-being and better clinical management of PC.

MicroRNA-138-5p targets the NFIB-Snail1 axis to inhibit colorectal cancer cell migration and chemoresistance

Background

Colorectal cancer ranks among the most lethal diseases worldwide. Although much progress has been made in research and treatment of colorectal cancer in recent years, the underlying mechanisms related to migration of the cancer cells and the reason for chemoresistance still remain unclear. In this research, we explored the underlying effect of miR-138-5p in colorectal cancer.

Methods

We used qRT-PCR to investigate the expression of miR-138-5p, Snail1, NFIB in colorectal cancer cells. Lentiviral vectors containing miR-138-5p mimics and inhibitors were constructed and transfected cells. Wound healing assay was applied to illustrate interferences on cell migration. Fluorouracial, doxorubicin, cisplat in were used to detect chemotherapy resistance. In order to identify target genes, bioinformatic methods were applied. Snail1 and NFIB protein expression in stable cell lines was detected using Western blot. Double luciferase and CHIP experiment were used to verify binding sites. We used rescue experiments to further explore the interactions among Snail1, NFIB and miR-138-5p.

Results

The expression of miR-138-5p in colorectal cancer cells was low. miR-138-5p inhibited cell migration in colorectal cancer, and could negatively regulate chemotherapy resistance. miR-138-5p targeted NFIB, and regulated Snail1 expression, which mediated colorectal cancer cell migration and chemotherapy resistance.

Conclusions

Our research indicates that miR-138-5p could be a crucial modulator controlling colorectal cancer cell migration and chemoresistance, by acting upon the NFIB-Snail1 axis. miR-138-5p has an emerging prospect to be exploited as a new target for colorectal cancer.

ERas regulates cell proliferation and epithelial-mesenchymal transition by affecting Erk/Akt signaling pathway in pancreatic cancer

Pancreatic cancer is the fourth most common lethal malignancy with an overall 5-year survival rate of less than 5%. ERas, a novel Ras family member, was first identified in murine embryonic stem cells and is upregulated in various cancers. However, the expression and potential role of ERas in pancreatic cancer have not been investigated. In this study, we found that ERas mRNA and protein were upregulated in pancreatic cancer tissues and cells compared with controls. Knockdown of ERas in pancreatic cancer cells by siRNA significantly decreased cell proliferation, colony formation, migration, and invasion and promoted cell apoptosis in vitro. Epithelial-mesenchymal transition (EMT) is closely related to tumor progression. We observed a significant decrease in N-cadherin expression in pancreatic cancer cells in response to ERas gene silencing by immunofluorescence assay and western blot. Furthermore, tumor growth and EMT were inhibited in xenografts derived from pancreatic cancer cells with ERas downregulation. We further investigated the regulatory mechanisms of ERas in pancreatic cancer and found that ERas may activate the Erk/Akt signaling pathway. Moreover, Erk inhibitor decreased pancreatic cancer cells proliferation and colony formation activities. Our data suggest that targeting ERas and its relevant signaling pathways might represent a novel therapeutic approach for the treatment of pancreatic cancer.

Cadherin 13 Inhibits Pancreatic Cancer Progression and Epithelial-mesenchymal Transition by Wnt/β-Catenin Signaling

Cadherin 13 (CDH13) is an atypical cadherin that exerts tumor-suppressive effects on cancers derived from epithelial cells. Although the CDH13 promoter is frequently hypermethylated in pancreatic cancer (PC), the direct impact of CDH13 on PC is unknown. Accordingly, the expression of CDH13 in PC cell lines and paired PC tissues was examined by immunohistochemistry, quantitative real-time PCR and western blotting. Our findings showed that CDH13 was downregulated in PC tissues and cell lines. Moreover, cell proliferation, migration and invasion were detected by CCK-8 assay, transwell migration assay and transwell invasion assay, respectively. Xenograft tumor experiments were used to determine the biological function of CDH13 in vivo. As revealed by our data, CDH13 overexpression significantly inhibited the proliferation, migration and invasion of human PC cells in vitro. The inhibitory effect of CDH13 on PC was further confirmed in animal models. Mice subcutaneously or orthotopically transplanted with CDH13-overexpressing CFPAC-1 cells developed significantly smaller tumors with less liver metastases and mesenteric metastases than those of the control group. Next, transcriptomics and western blot analysis were used to identify the underlying mechanisms. Further molecular mechanism studies showed that CDH13 overexpression inhibited the activation of the Wnt/β-catenin signaling pathway and regulated the expression of epithelial-mesenchymal transition (EMT)-related markers. Our results indicated that CDH13 displayed an inhibitory effect on PC and suggested that CDH13 might be a potential biomarker and a new therapeutic target for PC.