Trametinib Potentiates Anti-PD-1 Efficacy in Tumors Established from Chemotherapy-Primed Pancreatic Cancer Cells.

Despite advances in immune checkpoint inhibitors, chemotherapy remains the standard therapy for patients with pancreatic ductal adenocarcinoma (PDAC). As the combinations of chemotherapy, including the FOLFIRINOX [5-fluorouracil, F; irinotecan, I; and oxaliplatin, O (FIO)] regimen, and immune checkpoint inhibitors have failed to demonstrate clinical benefit in patients with metastatic PDAC tumors, there is increasing interest in identifying therapeutic approaches to potentiate ICI efficacy in patients with PDAC. In this study, we report that neoadjuvant FOLFIRINOX-treated human PDAC tumors exhibit increased MEK/ERK activation.

Targeting BCL2 with Venetoclax Enhances the Efficacy of the KRASG12D Inhibitor MRTX1133 in Pancreatic Cancer.

MRTX1133 is currently being evaluated in patients with pancreatic ductal adenocarcinoma (PDAC) tumors harboring a KRASG12D mutation. Combination strategies have the potential to enhance the efficacy of MRTX1133 to further promote cell death and tumor regression. In this study, we demonstrated that MRTX1133 increased the levels of the proapoptotic protein BIM in PDAC cells and conferred sensitivity to the FDA-approved BCL2 inhibitor venetoclax.

BET Inhibition Rescues Acinar-Ductal-Metaplasia and Ciliogenesis and Ameliorates Chronic Pancreatitis-Driven Changes in Mice With Loss of the Polarity Protein Par3.

Background & Aims: The apical-basal polarity of pancreatic acinar cells is essential for maintaining tissue architecture. However, the mechanisms by which polarity proteins regulate acinar pancreas injury and regeneration are poorly understood.

Methods: Cerulein-induced pancreatitis was induced in mice with conditional deletion of the polarity protein Par3 in the pancreas.

Inhibition of MNKs promotes macrophage immunosuppressive phenotype to limit CD8+ T cell antitumor immunity.

To elicit effective antitumor responses, CD8+ T cells need to infiltrate tumors and sustain their effector function within the immunosuppressive tumor microenvironment (TME). Here, we evaluate the role of MNK activity in regulating CD8+ T cell infiltration and antitumor activity in pancreatic and thyroid tumors. We first show that human pancreatic and thyroid tumors with increased MNK activity are associated with decreased infiltration by CD8+ T cells.

Gα13 loss in Kras/Tp53 mouse model of pancreatic tumorigenesis promotes tumors susceptible to rapamycin.

Gα13 transduces signals from G-protein-coupled receptors. While Gα13 functions as a tumor suppressor in lymphomas, it is not known whether Gα13 is pro-tumorigenic or tumor suppressive in genetically engineered mouse (GEM) models of epithelial cancers. Here, we show that loss of Gα13 in the Kras/Tp53 (KPC) GEM model promotes well-differentiated tumors and reduces survival.

Preclinical Models of Pancreatic Ductal Adenocarcinoma and Their Utility in Immunotherapy Studies.

The advent of immunotherapy has transformed the treatment landscape for several human malignancies. Antibodies against immune checkpoints, such as anti-PD-1/PD-L1 and anti-CTLA-4, demonstrate durable clinical benefits in several cancer types. However, checkpoint blockade has failed to elicit effective anti-tumor responses in pancreatic ductal adenocarcinoma (PDAC), which remains one of the most lethal malignancies with a dismal prognosis.

Quercetin Enhances the Anti-Tumor Effects of BET Inhibitors by Suppressing hnRNPA1.

Bromodomain and extraterminal domain (BET) proteins, which are important epigenetic readers, are often dysregulated in cancer. While a number of BET inhibitors are currently in early phase clinical trials, BET inhibitors show limited single-agent activity. The purpose of this study is to determine if Quercetin, a naturally occurring polyphenolic flavonoid often found abundant in fruits and vegetables, can enhance the anti-tumor effects of BET inhibitors.

Neutrophil extracellular traps produced during inflammation awaken dormant cancer cells in mice.

Cancer cells from a primary tumor can disseminate to other tissues, remaining dormant and clinically undetectable for many years. Little is known about the cues that cause these dormant cells to awaken, resume proliferating, and develop into metastases. Studying mouse models, we found that sustained lung inflammation caused by tobacco smoke exposure or nasal instillation of lipopolysaccharide converted disseminated, dormant cancer cells to aggressively growing metastases.

Interplay between interferon regulatory factor 1 and BRD4 in the regulation of PD-L1 in pancreatic stellate cells.

The fibrotic reaction is a characteristic feature of human pancreatic ductal adenocarcinoma (PDAC) tumors. It is associated with activation and proliferation of pancreatic stellate cells (PSCs), which are key regulators of fibrosis in vivo. While there is increasing interest in the regulation of PD-L1 expression in cancer and immune cells, the expression and regulation of PD-L1 in other stromal cells, such as PSCs, has not been fully evaluated.

Snail cooperates with KrasG12D to promote pancreatic fibrosis.

Unlabelled: Patients with pancreatic cancer, which is characterized by an extensive collagen-rich fibrotic reaction, often present with metastases. A critical step in cancer metastasis is epithelial-to-mesenchymal transition (EMT), which can be orchestrated by the Snail family of transcription factors. To understand the role of Snail (SNAI1) in pancreatic cancer development, we generated transgenic mice expressing Snail in the pancreas.

Interplay between β1-integrin and Rho signaling regulates differential scattering and motility of pancreatic cancer cells by snail and Slug proteins.

The Snail family of transcription factors has been implicated in pancreatic cancer progression. We recently showed that Snail (Snai1) promotes membrane-type 1 matrix metalloproteinase (MT1-MMP)- and ERK1/2-dependent scattering of pancreatic cancer cells in three-dimensional type I collagen. In this study, we examine the role of Slug (Snai2) in regulating pancreatic cancer cell scattering in three-dimensional type I collagen.

Biochemical role of the collagen-rich tumour microenvironment in pancreatic cancer progression.

PDAC (pancreatic ductal adenocarcinoma) is among the most deadly of human malignances. A hallmark of the disease is a pronounced collagen-rich fibrotic extracellular matrix known as the desmoplastic reaction. Intriguingly, it is precisely these areas of fibrosis in which human PDAC tumours demonstrate increased expression of a key collagenase, MT1-MMP [membrane-type 1 MMP (matrix metalloproteinase); also known as MMP-14].

Contribution of epithelial-to-mesenchymal transition and cancer stem cells to pancreatic cancer progression.

Pancreatic adenocarcinoma remains among the most lethal of human malignancies. Overall 5-y survival is less than 5%, and only 20% of patients presenting with localized disease amenable to surgical resection. Even in patients who undergo resection, long-term survival remains extremely poor.

MT1-MMP cooperates with Kras(G12D) to promote pancreatic fibrosis through increased TGF-β signaling.

Pancreatic cancer is associated with a pronounced fibrotic reaction that was recently shown to limit delivery of chemotherapy. To identify potential therapeutic targets to overcome this fibrosis, we examined the interplay between fibrosis and the key proteinase membrane type 1-matrix metalloproteinase (MT1-MMP, MMP-14), which is required for growth and invasion in the collagen-rich microenvironment. In this article, we show that compared with control mice (Kras(+)/MT1-MMP(-)) that express an activating Kras(G12D) mutation necessary for pancreatic cancer development, littermate mice that express both MT1-MMP and Kras(G12D) (Kras(+)/MT1-MMP(+)) developed a greater number of large, dysplastic mucin-containing papillary lesions.

Ethanol differentially regulates snail family of transcription factors and invasion of premalignant and malignant pancreatic ductal cells.

Pancreatic cancer is one of the deadliest of cancers with a dismal 5-year survival rate. Epidemiological studies have identified chronic pancreatitis as a risk factor for pancreatic cancer. Pancreatic cancer cells also demonstrate increased expression of the transcription factor Snail, a key regulator of epithelial-mesenchymal transition.

Pancreatic cancer cells respond to type I collagen by inducing snail expression to promote membrane type 1 matrix metalloproteinase-dependent collagen invasion.

Pancreatic ductal adenocarcinoma (PDAC) is characterized by pronounced fibrotic reaction composed primarily of type I collagen. Although type I collagen functions as a barrier to invasion, pancreatic cancer cells have been shown to respond to type I collagen by becoming more motile and invasive. Because epithelial-mesenchymal transition is also associated with cancer invasion, we examined the extent to which collagen modulated the expression of Snail, a well known regulator of epithelial-mesenchymal transition.

Three-dimensional collagen I promotes gemcitabine resistance in pancreatic cancer through MT1-MMP-mediated expression of HMGA2.

One of the hallmarks of human pancreatic ductal adenocarcinoma (PDAC) is its pronounced type I collagen-rich fibrotic reaction. Although recent reports have shown that the fibrotic reaction can limit the efficacy of gemcitabine chemotherapy, the underlying mechanisms remain poorly understood. In this article, we show that the type I collagen allows PDAC cells to override checkpoint arrest induced by gemcitabine.

Role of interferon {alpha} (IFN{alpha})-inducible Schlafen-5 in regulation of anchorage-independent growth and invasion of malignant melanoma cells.

IFNα exerts potent inhibitory activities against malignant melanoma cells in vitro and in vivo, but the mechanisms by which it generates its antitumor effects remain unknown. We examined the effects of interferon α (IFNα) on the expression of human members of the Schlafen (SLFN) family of genes, a group of cell cycle regulators that mediate growth-inhibitory responses. Using quantitative RT-real time PCR, we found detectable basal expression of all the different human SLFN genes examined (SLFN5, SLFN11, SLFN12, SLFN13, and SLFN14), in malignant melanoma cells and primary normal human melanocytes, but SLFN5 basal expression was suppressed in all analyzed melanoma cell lines.

Rho-ROCK-myosin signaling mediates membrane type 1 matrix metalloproteinase-induced cellular aggregation of keratinocytes.

Membrane type 1-matrix metalloproteinase (MT1-MMP, MMP14), which is associated with extracellular matrix (ECM) breakdown in squamous cell carcinoma (SCC), promotes tumor formation and epithelial-mesenchymal transition. However, in this report we demonstrate that MT1-MMP, by cleaving the underlying ECM, causes cellular aggregation of keratinocytes and SCC cells. Treatment with an MMP inhibitor abrogated MT1-MMP-induced phenotypic changes, but decreasing E-cadherin expression did not affect MT1-MMP-induced cellular aggregation.

Contribution of epithelial-mesenchymal transition to pancreatic cancer progression.

Pancreatic adenocarcinoma (PDAC) is one of the most lethal human malignancies, with median survival of less than one year and overall five-year survival of less than 5%. There is increasing evidence demonstrating that epithelial-mesenchymal transition (EMT) contributes to pancreatic cancer metastasis and to treatment resistance. In this review, we will examine the data demonstrating the role and regulation of EMT in pancreatic cancer progression, focusing particularly on the transcription factors and microRNAs involved in EMT.

Slug is a downstream mediator of transforming growth factor-beta1-induced matrix metalloproteinase-9 expression and invasion of oral cancer cells.

Members of Snail family of transcription factors play an important role in oral cancer progression by inducing epithelial-mesenchymal transition, by promoting invasion and by increasing matrix metalloproteinase (MMP) expression. Although Snail (Snai1) is the best characterized and the most extensively studied member of this family, the role and regulation of Slug (Snai2) in oral cancer progression is less well understood. In this report, we show that transforming growth factor-beta1 (TGF-beta1) increases Slug levels in tert-immortalized oral keratinocytes and in malignant oral squamous cell carcinoma (OSCC) cells.

Inhibition of CYP1A1 by Quassinoids found in Picrasma excelsa.

Infusions of the plant Picrasma excelsa, known as Jamaican bitterwood tea, are commonly consumed to lower blood sugar levels in diabetics who are already on prescription medicines. We therefore investigated the inhibition properties of this tea against a panel of cytochrome P450 (CYP) enzymes, which are primarily responsible for the metabolism of a majority of drugs on the market. The two major ingredients, quassin and neoquassin, were then isolated and used for further characterization.