Sonic Hedgehog Promotes Desmoplasia in Pancreatic Cancer

Abstract

Purpose: We investigated the contribution of Sonic hedgehog (SHH) to pancreatic cancer progression. Experimental Design: We expressed SHH in a transformed primary ductal-derived epithelial cell line from the human pancreas, transformed hTert-HPNE (T-HPNE), and evaluated the effects on tumor growth.We also directly inhibited the activity of SHH in vivo by administering a blocking antibody to mice challenged orthotopically with the Capan-2 pancreatic cancer cell line, which is known to express SHH and form moderately differentiated tumors in nude mice. Results: Our data provide evidence that expression of SHH influences tumor growth by contributing to the formation of desmoplasia in pancreatic cancer. We further show that SHH affects the differentiation and motility of human pancreatic stellate cells and fibroblasts. Conclusions: These data suggest that SHH contributes to the formation of desmoplasia in pancreatic cancer, an important component of the tumor microenvironment.Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States, resulting in 30,000 deaths each year, in part because it is one of the most lethal cancers with a death-to-incidence ratio of 0.99 (1). The lethality of pancreatic cancer is largely due to late stage of diagnosis and resistance to current therapies. More than 80% of patients are unresectable and most present with metastatic disease due to aggressive localized invasion and a high incidence of early metastasis (2). Worldwide, the incidence of death from pancreatic cancer has increased, which, together with the lack of current therapies, emphasizes the need to determine the mechanisms of pancreatic cancer progression and better targets for diagnosis and treatment.The current model of pancreatic cancer progression includes mutations that activate K-ras, followed by inactivating mutations or loss of expression of tumor suppressor genes including p53, p16INK4A , and SMAD4 (3). Sonic hedgehog (SHH) and other proteins downstream of the hedgehog pathway were recently detected in precursor lesions and samples of primary tumors from patients with pancreatic adenocarcinoma, which implicates this pathway in the initiation and progression of pancreatic cancer given its absence in normal adult pancreas (4, 5). Transgenic mouse models in which SHH was expressed in mouse pancreatic epithelium, in concert with activated Ras signaling, enhanced the formation of pancreatic intraepithelial neoplasia and accelerated lethality, further supporting a role for hedgehog as an early contributor to this lethal disease (6). We investigated the contribution of SHH to pancreatic cancer progression by expressing SHH in a transformed primary ductal-derived epithelial cell line from the human pancreas, transformed hTert-HPNE (T-HPNE), which was described previously (7,8). This cell line has been documented to represent an appropriate and important model system to delineate signaling mechanisms for Ras-mediated oncogenesis and growth of pancreatic ductal epithelial cells (8), and...

MYB Promotes Desmoplasia in Pancreatic Cancer through Direct Transcriptional Up-regulation and Cooperative Action of Sonic Hedgehog and Adrenomedullin

“…1A). This observation was further confirmed by immunostaining the tumor sections for collagen I, fibronectin, and ␣-SMA, which are well-characterized markers of desmoplasia (5). A dramatic decrease in the expression of collagen I, fibronectin, and ␣-SMA was detected in tumors generated from MiaPaCa-shMYB cells compared with those derived from MiaPaCa-NT-Scr cells (Fig.…”

“…4 Among several differentially expressed genes, we found a decreased expression of ADM (adrenomedullin) and SHH (sonic hedgehog) in MYBsilenced cells, which have previously been implicated in the development of desmoplasia in pancreatic tumors (5,18). To ascertain the effect of MYB silencing on ADM and SHH, we analyzed their expression in MYB-expressing (MiaPaCa-NTScr) and -silenced (MiaPaCa-shMYB) cells as well as MYB-null BxPC3 and ectopically MYB-expressing BxPC3-MYB cells at both mRNA (by quantitative RT-PCR) and protein (by immunoblot) levels.…”

“…Desmoplasia is characterized by an increase in the presence of ␣-smooth muscle actin (␣-SMA)-positive fibroblasts (myofibroblasts or activated pancreatic stellate cells) along with extensive deposition of extracellular matrix (ECM) proteins (5). This desmoplastic reaction not only gives pancreatic tumors their characteristic histoarchitecture, but is suggested to play important roles in disease progression and chemoresistance (6).…”

“…Pancreatic stellate cells (PSCs) are the major cellular component of the desmoplastic stroma that synthesize and secrete several ECM components within tumor microenvironment (7)(8)(9)(10). Pancreatic tumor cell-derived signaling ligands have been shown to promote proliferation and differentiation of PSCs, and targeting of these signaling nodes is suggested to improve the efficacy of chemotherapy in preclinical models (5,6).…”

Arsenic against the hedgehog

“…5 Duke's Chen also wanted to see how ATO affects the translocation of GLI2 from the cytosol to the nucleus. "Because GLI2 is a transcription factor, it needs to enter the nucleus to carry out its function.…”