SEMA7A-mediated juxtacrine stimulation of IGFBP-3 upregulates IL-17RB at pancreatic cancer invasive front.

Tumor invasion is the hallmark of tumor malignancy. The invasive infiltration pattern of tumor cells located at the leading edge is highly correlated with metastasis and unfavorable patient outcomes. However, the regulatory mechanisms governing tumor malignancy at the invasive margin remain unclear. The IL-17B/IL-17RB pathway is known to promote pancreatic cancer invasion and metastasis, yet the specific mechanisms underlying IL-17RB upregulation during invasion are poorly understood. In this study, we unveiled a multistep process for IL-17RB upregulation at the invasive margin, which occurs through direct communication between tumor cells and fibroblasts. Tumor ATP1A1 facilitates plasma membrane expression of SEMA7A, which binds to and induces IGFBP-3 secretion from fibroblasts. The resulting gradient of IGFBP-3 influences the direction and enhances IL-17RB expression to regulate SNAI2 in invasion. These findings highlight the importance of local tumor-fibroblast interactions in promoting cancer cell invasiveness, potentially leading to the development of new therapeutic strategies targeting this communication.

Exosomal miRNA 16-5p/29a-3p from pancreatic cancer induce adipose atrophy by inhibiting adipogenesis and promoting lipolysis.

Over 80% of the patients with pancreatic ductal adenocarcinoma (PDAC) have cachexia/wasting syndrome. Cachexia is associated with reduced survival, decreased quality of life, and higher metastasis rates. Here, we demonstrate that fat loss is the earliest feature of PDAC-exosome-induced cachexia. MicroRNA sequencing of exosomal components from normal and cancer-derived exosomes revealed enrichment of miR-16-5p, miR-21-5p, miR-29a-3p, and miR-125b-5p in serum exosomes of mice harboring PDAC and patients with PDAC. Further, miR-16-5p and miR-29a-3p inhibited adipogenesis through decreasing Erlin2 and Cmpk1 expression which downregulates C/EBPß and PPARγ. Synergistically, miR-29a-3p promotes lipolysis through increasing ATGL expression by suppressing MCT1 expression. Furthermore, PDAC-exosomes deprived of miR-16-5p and miR-29a-3p fail to induce fat loss. Hence, miR-16-5p and miR-29a-3p exosomal miRs are essential for PDAC-induced fat loss. Thus, we unravel that PDAC induces adipose atrophy via exosomal miRs. This knowledge may provide new diagnostic and therapeutic strategies for PDAC-induced cachexia.

Pancreatic cancer-derived small extracellular vesical ezrin activates fibroblasts to exacerbate cancer metastasis through STAT3 and YAP-1 signaling pathways.

Cancer-associated fibroblasts (CAFs), a major component of the tumor microenvironment (TME) in pancreatic ductal adenocarcinoma (PDAC), play an important role in tumorigenesis, metastasis, and chemoresistance. Tumor-derived small extracellular vesicles (sEVs), which mediate cell-to-cell communication between cancer cells and fibroblasts, are also critical for cancer progression and metastasis. However, it remains unclear how PDAC cell-derived sEVs activate fibroblasts, which contributes to tumor progression. Here, we report that ezrin (EZR) expression in PDAC cell-derived sEVs (sEV-EZR) can activate fibroblasts, resulting in increased migration ability and high expression of α-SMA, PDGFRB, and high production of extracellular matrix in fibroblasts. Reciprocally, sEV-EZR-activated fibroblasts enhanced PDAC cell proliferation, invasion, and metastasis to the liver in animal models. Conversely, fibroblasts treated with PDAC cell-derived sEVs with EZR knockdown resulted in the reduced metastatic ability of PDAC. Mechanistically, we demonstrated that PDAC cell-derived sEV-EZR increases the STAT3 and YAP-1 signaling pathways to induce fibroblast activation, and the activated fibroblasts promote PDAC cell proliferation, invasion, and liver metastasis. Inhibition of the STAT3 and YAP-1 signaling pathways by gene knockdown can abrogate sEV-EZR-induced effects. These findings suggest that targeting the interaction between PDAC cell-derived sEV-EZR and fibroblasts is a potential therapeutic strategy for PDAC.

High Glucose Triggers Nucleotide Imbalance through O-GlcNAcylation of Key Enzymes and Induces KRAS Mutation in Pancreatic Cells.

KRAS mutations are the earliest events found in approximately 90% of pancreatic ductal adenocarcinomas (PDACs). However, little is known as to why KRAS mutations preferentially occur in PDACs and what processes/factors generate these mutations. While abnormal carbohydrate metabolism is associated with a high risk of pancreatic cancer, it remains elusive whether a direct relationship between KRAS mutations and sugar metabolism exists. Here, we show that under high-glucose conditions, cellular O-GlcNAcylation is significantly elevated in pancreatic cells that exhibit lower phosphofructokinase (PFK) activity than other cell types. This post-translational modification specifically compromises the ribonucleotide reductase (RNR) activity, leading to deficiency in dNTP pools, genomic DNA alterations with KRAS mutations, and cellular transformation. These results establish a mechanistic link between a perturbed sugar metabolism and genomic instability that induces de novo oncogenic KRAS mutations preferentially in pancreatic cells.

The Shp2-induced epithelial disorganization defect is reversed by HDAC6 inhibition independent of Cdc42.

Regulation of Shp2, a tyrosine phosphatase, critically influences the development of various diseases. Its role in epithelial lumenogenesis is not clear. Here we show that oncogenic Shp2 dephosphorylates Tuba to decrease Cdc42 activation, leading to the abnormal multi-lumen formation of epithelial cells. HDAC6 suppression reverses oncogenic Shp2-induced multiple apical domains and spindle mis-orientation during division in cysts to acquire normal lumenogenesis. Intriguingly, Cdc42 activity is not restored in this rescued process. We present evidence that simultaneous reduction in myosin II and ERK1/2 activity by HDAC6 inhibition is responsible for the reversion. In HER2-positive breast cancer cells, Shp2 also mediates Cdc42 repression, and HDAC6 inhibition or co-suppression of ERK/myosin II promotes normal epithelial lumen phenotype without increasing Cdc42 activity. Our data suggest a mechanism of epithelial disorganization by Shp2 deregulation, and reveal the cellular context where HDAC6 suppression is capable of establishing normal epithelial lumenogenesis independent of Cdc42.

Src-dependent phosphorylation of ROCK participates in regulation of focal adhesion dynamics.

When a cell migrates, the RhoA-ROCK-mediated contractile signal is suppressed in the leading edge to allow dynamic adhesions for protrusion. However, several studies have reported that RhoA is indeed active in the leading edge of a migrating cell during serum stimulation. Here, we present evidence that regulation of ROCKII phosphorylation at the Y722 site in peripheral focal contacts is crucial for controlling the turnover of the focal adhesion (FA) complex uncoupled from RhoA activation during serum-stimulated migration. However, this phosphorylation control is dispensable for migration when RhoA is downregulated in cells treated with platelet-derived growth factor (PDGF). We further present evidence that ROCKII is phosphorylated by Src in FAs and this phosphorylation event decreases RhoA binding activity of ROCKII. Lack of this regulatory control leads to sustained myosin-mediated contractility and FA elongation during lysophosphatidic acid (LPA) stimulation. Altogether, our data suggest that Src-dependent ROCKII phosphorylation provides a means of tuning contractility required for FAs dynamics when RhoA is active.