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Secretory mucin 5AC promotes neoplastic progression by augmenting KLF4-mediated pancreatic cancer cell stemness

ABSTRACT: Pancreatic cancer (PC) is the third deadliest malignancy with a dismal five-year survival rate. The KrasG12D initiator mutation, present in 95% of the PC patients, leads to the development of pancreatic intraepithelial neoplasia (PanIN). The PanIN lesions, the most common precursor lesion of PC, exhibit de novo expression of mucins, which significantly contributes to PC pathobiology. The poor clinical outcome of PC warrants the identification of molecular player(s) that facilitate the progression of Kras-driven precursor lesions to invasive ductal carcinoma. Gel-forming mucin 5AC (MUC5AC) is one of the top differentially expressed genes in PC as compared to the normal pancreas. The expression of MUC5AC appears de-novo at PanIN-1A stage and elevates in tumor tissues, while remaining absent in the normal pancreas. To delineate the mechanistic contribution of Muc5ac in PC pathology, we genetically depleted Muc5ac in an autochthonous murine model (KrasG12D; Pdx-1cre, KC), which mirrors the early stages of PC. The onset of neoplastic growth and the progression of low-grade to high-grade PanIN lesions were significantly delayed in Muc5ac knockout (KrasG12D; Muc5ac-/-; Pdx-1cre, KCM) animals. We utilized high-throughput RNA seq. analysis to investigate the downstream molecular targets of Muc5ac-associated PC progression. Our study demonstrated that knockout of Muc5ac led to a significant decline in the genes associated with cancer stem cell (CSC) maintenance and epithelial-to-mesenchymal transition (EMT). The contribution of MUC5AC in CSC maintenance was validated via in vitro experiments, and tumor formation frequency using limiting dilution assay upon subcutaneous administration.

ORGANISM(S): Mus musculus

PROVIDER: GSE160029 | GEO | 2020/10/25

REPOSITORIES: GEO

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Project description:The objective of this study was to elucidate the role of Nupr1 in pancreatic tumorigenesis. Using the Pdx-1-cre;LSL-KrasG12D mouse as model we discovered that, in contrast to KrasG12D pancreas that develop multiple foci of pancreatic intraepithelial neoplasia (PanIN), KrasG12D;Nupr1KO pancreas were free from such lesions, indicating that Nupr1 is pivotal for PanIN formation. In vitro, MiaPaCa2 cells activated Nupr1 expression in response to nutrient deprivation and this expression was necessary for cell survival. Mechanistically, Nupr1 protected cells from stress-induced death by inhibiting apoptosis through an alternative RelBàIER3-dependent pathway and independent from activation of the classical RelA-based NF-kB pathway. In agreement with these findings, Nupr1, RelB and IER3 proteins were found co-expressed in PanINs from KrasG12D pancreas. Moreover, pancreas-specific KrasG12D;RelbDpanc mice displayed a delay in PanIN development associated with a lack of IER3 expression, further emphasizing the relevance of this pathway in vivo. Efficient PanIN formation was therefore dependent on the expression of Nupr1 and RelB, with the probable involvement of IER3. Finally, a significant correlation between expression of Nupr1, RelB and IER3 and a poor prognosis of patients with PDAC was found. Altogether, our results reveal a novel stress-related pathway that requires the functional interaction of Nupr1àRelBàIER3 in KrasG12D-dependent transformation of the pancreas and expand our understanding of the molecular machinery that mediates the early steps of pancreatic carcinogenesis. Since Nupr1 belongs to the HMG family of chromatin remodelers with transcriptional co-factor activity, Nupr1 could increase cell survival in a nutrient-deprived microenvironment by activating the expression of pro-survival genes. Moreover, considering that RelB, and not RelA/p65, is essential to the Nupr1-mediated survival mechanism that takes place upon nutrient deprivation-induced stress, we made the hypothesis that the two NF-kB transcription factors should activate different sets of genes among which a pivotal pro-survival gene would be exclusively dependent on RelB. In order to test this two hypothesis, an Affymetrix microarray analysis was performed using pancreatic cancer cells transfected with siCtrl or siNupr1 and cultured for 3, 6 or 9 hrs in EBSS; or transfected with siRelB, siRelA/p65 or siCtrl and cultured for 9 hrs in EBSS or Mock.

Project description:Background: With less than a 5% survival rate pancreatic adenocarcinoma (PDAC) is almost uniformly lethal. In order to make a significant impact on survival of patients with this malignancy, it is necessary to diagnose the disease early, when curative surgery is still possible. Detailed knowledge of the natural history of the disease and molecular events leading to its progression is therefore critical. Methods and Findings: We have analysed the precursor lesions, PanINs, from prophylactic pancreatectomy specimens of patients from four different kindreds with high risk of familial pancreatic cancer who were treated for histologically proven PanIN-2/3. Thus, the material was procured before pancreatic cancer has developed, rather than from PanINs in a tissue field that already contains cancer. Genome-wide transcriptional profiling using such unique specimens was performed. Bulk frozen sections displaying the most extensive but not microdissected PanIN-2/3 lesions were used in order to obtain the holistic view of both the precursor lesions and their microenvironment. A panel of 76 commonly dysregulated genes that underlie neoplastic progression from normal pancreas to PanINs and PDAC were identified. In addition to shared genes some differences between the PanINs of individual families as well as between the PanINs and PDACs were also seen. This was particularly pronounced in the stromal and immune responses. Conclusions: Our comprehensive analysis of precursor lesions without the invasive component provides the definitive molecular proof that PanIN lesions beget cancer from a molecular standpoint. We demonstrate the need for accumulation of transcriptomic changes during the progression of PanIN to PDAC, both in the epithelium and in the surrounding stroma. An identified 76-gene signature of PDAC progression presents a rich candidate pool for the development of early diagnostic and/or surveillance markers as well as potential novel preventive/therapeutic targets for both familial and sporadic pancreatic adenocarcinoma. Gene expression of 13 PanIN samples was compared to profiling data of whole biopsies from normal donor pancreas (N1 to 4, two replicated samples) and sporadic PDAC (PDAC1 to 6).Ttwo PDAC samples (PDAC 3 and 4) and a replicate of one normal specimen (N4) were removed during the hybridisation quality assessment.

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Secretory mucin 5AC promotes neoplastic progression by augmenting KLF4-mediated pancreatic cancer cell stemness

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