p53-Independent negative regulation of p21/cyclin-dependent kinase-interacting protein 1 by the sonic hedgehog-glioma-associated oncogene 1 pathway in gastric carcinoma cells

The activation of Hedgehog (Hh) signaling has been implicated in the growth of various tumor types, including gastric carcinoma. However, the precise mechanisms of Hh activation and suppression of tumor growth by the blockade of Hh signaling in gastric carcinoma cells remain unknown. The aim of this study was to elucidate the mechanism of abnormal Hh signaling and the key molecules contributing to dysregulated growth of gastric carcinoma. The Sonic hedgehog (Shh) ligand and its receptor Patched were expressed in all five gastric carcinoma cell lines examined (MKN1, MKN7, MKN45, MKN74, and AGS cells). The blockade of Hh signaling with anti-Shh antibody inhibited the growth of all five gastric carcinoma cell lines. Shh was overexpressed (mean, 12.8-fold) in 8 of 14 (57.0%) cancerous tissue samples from patients with gastric carcinoma as compared with expression in the surrounding noncancerous tissues. The disruption of glioma-associated oncogene 1 (Gli1) by small interfering RNA induced an increase in p21/cyclin-dependent kinase-interacting protein 1 (CIP1), interfered with the G1-S transition, and suppressed cell proliferation. The stimulation or inhibition of Hh signaling did not affect p53 activity and the induction of p21/CIP1 expression and the G1 arrest by inhibition of Hh signaling were not affected by the p53 status. These findings suggest that the overexpression of Shh contributes to constitutive Hh activation and that this signaling pathway negatively regulates p21/CIP1 through a Gli1-dependent and p53-independent mechanism in gastric carcinoma cells.     

New therapeutic strategy for cancer targeting the hedgehog signaling pathway

The hedgehog (Hh) signaling pathway was originally found as an organizer in embryonic development. The pathway is now implicated in the development of various tumors. Recently, it has been reported that the pathway activation is resulted from aberrant expression of the ligand, Sonic Hh (Shh), in pancreatic cancer and breast cancer. Here we developed a new strategy to control the activation of the Hh signaling pathway in cancer cells, which have ectopic and ligand dependent activation of the Hh signaling pathway. Our strategy may contribute to the development of a new cancer treatment.     

TAK‐441, a novel investigational smoothened antagonist,delays castration‐resistant progression in prostate cancer by disrupting paracrine hedgehog signaling

Hedgehog (Hh) signaling is a highly conserved intercellular and intracellular communication mechanism that governs organogenesis and is dysregulated in cancers of numerous tissues, including prostate. Up‐regulated expression of the Hh ligands, Sonic (Shh) and Desert (Dhh), has been reported in androgen‐deprived and castration‐resistant prostate cancer (CRPC). In a cohort of therapy naive, short‐ and long‐term neoadjuvant hormone therapy‐treated (NHT), and CRPC specimens, we observed elevated Dhh expression predominantly in long‐term NHT specimens and elevated Shh expression predominantly in CRPC specimens. Together with previously demonstrated reciprocal signaling between Shh‐producing prostate cancer (PCa) cells and urogenital mesenchymal fibroblasts, these results suggest that castration‐induced Hh expression promotes CRPC progression through reciprocal paracrine signaling within the tumor microenvironment. We tested whether the orally available Smoothened (Smo) antagonist, TAK‐441, could impair castration‐resistant progression of LNCaP PCa xenografts by disrupting paracrine Hh signaling. Although TAK‐441 or cyclopamine did not affect androgen withdrawal‐induced Shh up‐regulation or viability of LNCaP cells, castration‐resistant progression of LNCaP xenografts was significantly delayed in animals treated with TAK‐441. In TAK‐441‐treated xenografts, expression of murine orthologs of the Hh‐activated genes, Gli1, Gli2 and Ptch1, was substantially suppressed, while expression of the corresponding human orthologs was unaffected. As androgen‐deprived LNCaP cells up‐regulate Shh expression, but are not sensitive to Smo antagonists, these studies indicate that TAK‐441 leads to delayed castration‐resistant progression of LNCaP xenografts by disrupting paracrine Hh signaling with the tumor stroma. Thus, paracrine Hh signaling may offer unique opportunities for prognostic biomarker development, drug targeting and therapeutic response monitoring of PCa progression.     

Hedgehog: an attribute to tumor regrowth after chemoradiotherapy and a target to improve radiation response.

PURPOSE: Despite aggressive chemotherapy, radiotherapy, surgery, or combination approaches, the survival rate of patients with esophageal cancer remains poor. Recent studies have suggested that constitutive activation of the Hedgehog (Hh) pathway in cancers of the digestive tract may contribute to the growth and maintenance of cancer. However, the relationship between Hh signaling and therapeutic response is unknown. EXPERIMENTAL DESIGN: The expression and temporal kinetics of Hh signaling and proliferation biomarkers after chemoradiotherapy were examined in esophageal tumor xenografts. Additionally, immunohistochemical analysis of Sonic Hh (Shh) and Gli-1 expression were done on residual tumors from patients who received neoadjuvant chemoradiotherapy followed by surgery. The ability of Shh signaling to induce proliferation in esophageal cell lines was determined. Expression of cell cycle checkpoint proteins was analyzed in cells in which Hh signaling was activated or inhibited. We further determined the effect of inhibiting Hh signaling in sensitizing esophageal tumors to radiation. RESULTS: We showed that the Shh signaling pathway was extensively activated in esophageal cancer xenografts and residual tumors after chemoradiotherapy and the temporal kinetics of Hh signaling preceded increases in proliferation biomarker expression and tumor size during tumor regrowth. We further showed that Hh pathway activity influences proliferation rates of esophageal cancer cell lines through up-regulation of the G1-cyclin-Rb axis. Additionally, we found that blocking Hh signaling enhanced radiation cytotoxicity of esophageal cancer cells. CONCLUSIONS: These results suggest that activation of the Hh pathway may promote tumor repopulation after chemoradiotherapy and contribute to chemoradiation resistance in esophageal cancers.     

Oestrogen receptor-�� contributes to the regulation of the hedgehog signalling pathway in ER��-positive gastric cancer

Background:

Oestrogen receptor-alpha (ERα) is highly expressed in diffuse-type gastric cancer and oestrogen increases the proliferation of ERα-positive gastric cancer. However, a detailed mechanism by which oestrogen increases the proliferation of these cells is still unclear.

Methods:

We used 17-β-oestradiol (E2) as a stimulator against the ERα pathway. Pure anti-oestrogen drug ICI 182 780 (ICI) and small interfering RNA against ERα (ERα siRNA) were used as inhibitors. Cyclopamine (Cyc) was used as the hedgehog (Hh) pathway inhibitor. Two human ERα-positive gastric cancer cells were used as target cells. Effects of the stimulator and inhibitor on E2-induced cell proliferation were also examined.

Results:

In ERα-positive cells, E2 increased not only cell proliferation but also one of the ligands of the Hh pathway, Shh expression. 17-β-Oestradiol-induced cell proliferation was suppressed by ICI, ERα siRNA or Cyc. The increased expression of Shh induced by E2 was suppressed by ICI and ERα siRNA but not by Cyc. Furthermore, recombinant Shh activated the Hh pathway and increased cell proliferation, whereas anti-Shh antibody suppressed E2-induced cell proliferation. When a relationship between ERα and Shh expressions was analysed using surgically resected gastric cancer specimens, a positive correlation was found, suggesting a linkage between the ERα and Hh pathways.

Conclusion:

Our data indicate that activation of the ERα pathway promotes cell proliferation by activating the Hh pathway in a ligand-dependent manner through Shh induction of ERα-positive gastric cancer.     

De-regulation of the sonic hedgehog pathway in the InsGas mouse model of gastric carcinogenesis

This study investigated sonic hedgehog (Shh) signalling in gastric metaplasia in the insulin-gastrin (InsGas) hypergastrinaemic mouse +/- Helicobacter felis (H. felis) infection. Sonic hedgehog gene and protein expression was reduced in pre-metaplastic lesions from non-infected mice (90% gene reduction, P<0.01) compared to normal mucosa. Sonic hedgehog was reactivated in gastric metaplasia of H. felis-infected mice (3.5-fold increase, P<0.01) compared to pre-metaplastic lesions. Additionally, the Shh target gene, glioma-associated oncogene (Gli)-1, was significantly reduced in the gastric glands of InsGas mice (75% reduction, P<0.05) and reactivated with H. felis infection (P<0.05, base of glands, P<0.01 stroma of metaplastic glands). The ability of H. felis to activate the Shh pathway was investigated by measuring the effect of target cytokine, interleukin-8 (IL-8), on Shh expression in AGS and MGLVA1 cells, which was shown to induce Shh expression at physiological concentrations. H. felis induced the expression of NF-kappaB in inflammatory infiltrates in vivo, and the expression of the IL-8 mouse homologue, protein KC, in inflammatory infiltrates and metaplastic lesions. Sonic hedgehog pathway reactivation was paralleled with an increase in proliferation of metaplastic lesions (15.75 vs 4.39% in infected vs non-infected mice, respectively, P<0.001). Furthermore, Shh overexpression increased the growth rate of the gastric cancer cell line, AGS. The antiapoptotic protein, bcl-2, was expressed in the stroma of infected mice, along with a second Shh target gene, patched-1 (P=0.0001, stroma of metaplastic gland). This study provides evidence suggesting reactivation of Shh signalling from pre-metaplastic to advanced metaplastic lesions of the stomach and outlines the importance of the Shh pathway as a potential chemoprophylactic target for gastric carcinogenesis.     

Cross‐signaling among phosphinositide‐3 kinase,mitogen‐activated protein kinase and sonic hedgehog pathways exists in esophageal cancer

The hedgehog (Hh) signaling pathway is essential for the development of tissues and organs. Hyperactive Hh signaling has been implicated in many gastric cancers, including esophageal cancer. However, the interaction between the Hh pathway and other potential signaling pathways in primary esophageal tumorigenesis has not been well investigated. In our study, we found that esophageal cancer cells expressed Hh signaling molecules and that the hyperexpression of Hh target genes was related to protein kinase B (AKT) activation but not extracellular signal‐regulated kinase activation. We analyzed the relationship between Gli1 or p‐AKT expression and clinicopathological features in esophageal carcinoma samples and found that Gli1 expression was associated with lymph vessel invasion (p = 0.016), blood vessel invasion (p = 0.006) and a poor prognosis (p = 0.003), and p‐AKT expression was associated with blood vessel invasion (p = 0.031) and a poor prognosis (p = 0.031). We also studied the relationship between Hh and phosphinositide‐3 kinase (PI3K)/AKT or mitogen‐activated protein kinase (MAPK) signaling pathways in both TE‐1 and TE‐10 cell lines. We found that the PI3K/AKT pathway played a critical role in Hh signaling after stimulation with epidermal growth factor, Gβγ and N‐Shh. Conversely, PI3K/AKT and MAPK signaling cooperated with the Shh pathway to promote esophageal cancer cell survival and proliferation. The results from esophageal cancer cells shed light on the significance of Hh signaling in esophageal tumor formation and the crosstalk of the Hh pathway with other basic signaling pathways, which is consistent with that observed in human tumor samples.     

Gli1 contributes to the invasiveness of pancreatic cancer through matrix metalloproteinase-9 activation

The hedgehog (Hh) signaling pathway has been reported to be associated with the growth of pancreatic cancer, but its role in the invasive phenotype is poorly understood. Therefore, we investigated the role of the Hh pathway in pancreatic cancer cell invasiveness using a Matrigel invasion assay. Blockade of the Hh pathway by cyclopamine inhibited pancreatic cancer cell invasion in association with a decreased expression of matrix metalloproteinase (MMP)-9. By contrast, activation of the Hh pathway by the addition of exogenous Sonic hedgehog increased cell invasion and MMP-9 expression. Stable transfection of pancreatic cancer cells with Gli1 increased their invasiveness, which was associated with activation of MMP-9. We also showed that inhibition of MMP-9 by small interfering RNA blocked the increased invasiveness of Gli1-transfected cells. Furthermore, inhibition of Gli1 by small interfering RNA suppressed the invasiveness and MMP-9 expression of pancreatic cancer cells. Taken together, these findings suggest that members of the Hh pathway, especially Gli1, play an important role in the invasiveness of pancreatic cancer cells through the regulation of MMP-9 expression. ( Cancer Sci 2008; 99: 1377–1384)     

Hedgehog/Gli promotes epithelial-mesenchymal transition in lung squamous cell carcinomas

Background

Squamous cell carcinomas (SCC) account for approximately 30% of non-small cell lung cancer. Investigation of the mechanism of invasion and metastasis of lung SCC will be of great help for the development of meaningful targeted therapeutics. This study is intended to understand whether the activation of Hedgehog (Hh) pathway is involved in lung SCC, and whether activated Hh signaling regulates metastasis through epithelial-mesenchymal transition (EMT) in lung SCC.

Methods

Two cohorts of patients with lung SCC were studied. Protein expression was examined by immunohistochemistry, Western blot, or immunofluorescence. Protein expression levels in tissue specimens were scored and correlations were analyzed. Vismodegib and a Gli inhibitor were used to inhibit Shh/Gli activity, and recombinant Shh proteins were used to stimulate the Hh pathway in lung SCC cell lines. Cell migration assay was performed in vitro.

Results

Shh/Gli pathway components were aberrantly expressed in lung SCC tissue samples. Gli1 expression was reversely associated with the expression of EMT markers E-Cadherin and β-Catenin in lung SCC specimens. Inhibition of the Shh/Gli pathway suppressed migration and up-regulated E-Cadherin expression in lung SCC cells. Stimulation of the pathway increased migration and down-regulated E-Cadherin expression in lung SCC cells.

Conclusions

Our results suggested that the Shh/Gli pathway may be critical for lung SCC recurrence, metastasis and resistance to chemotherapy. Inhibition of the Shh/Gli pathway activity/function is a potential therapeutic strategy for the treatment of lung SCC patients.     

Ectopic Overexpression of Sonic Hedgehog (Shh) Induces Stromal Expansion and Metaplasia in the Adult Murine Pancreas

Ligand-dependent activation of the Hedgehog (Hh) signaling pathway has been implicated in both tumor initiation and metastasis of pancreatic ductal adenocarcinoma (PDAC). Prior studies in genetically engineered mouse models (GEMMs) have assessed the role of Hh signaling by cell autonomous expression of a constitutively active Gli2 within epithelial cells. On the contrary, aberrant pathway reactivation in the human exocrine pancreas occurs principally as a consequence of Sonic Hh ligand (Shh) overexpression from epithelial cells. To recapitulate the cognate pathophysiology of Hh signaling observed in the human pancreas, we examined GEMM where Hh ligand is conditionally overexpressed within the mature exocrine pancreas using a tamoxifen-inducible Elastase-Cre promoter (Ela-CreERT2;LSL-mShh). We also facilitated potential cell autonomous epithelial responsiveness to secreted Hh ligand by generating compound transgenic mice with concomitant expression of the Hh receptor Smoothened (Ela-CreERT2;LSL-mShh;LSL-mSmo). Of interest, none of these mice developed intraductal precursor lesions or PDAC during the follow-up period of up to 12 months after tamoxifen induction. Instead, all animals demonstrated marked expansion of stromal cells, consistent with the previously described epithelial-to-stromal paracrine Hh signaling. Hh responsiveness was mirrored by the expression of primary cilia within the expanded mesenchymal compartment and the absence within mature acinar cells. In the absence of cooperating mutations, Hh ligand overexpression in the mature exocrine pancreas is insufficient to induce neoplasia, even when epithelial cells coexpress the Smo receptor. This autochthonous model serves as a platform for studying epithelial stromal interactions in pancreatic carcinogenesis.     

Induction of interleukin-8 (CXCL-8) by tumor necrosis factor-alpha and leukemia inhibitory factor in pancreatic carcinoma cells: Impact of CXCL-8 as an autocrine growth factor

Pancreatic carcinoma is one of the most lethal of the gastrointestinal malignant tumors. Chronic inflammation leads to cancer development and progression. Interleukin-8 (CXCL-8) is a CXC chemokine, which plays an important role in neutrophil chemotaxis and activation. We previously reported that CXCL-8 was produced by a variety of human carcinoma cells and tissues, and that CXCL-8 promoted proliferation in pancreatic carcinoma cells (SUIT-2). In the present study, we analyzed whether various cytokines affect cell proliferation by CXCL-8 expression in pancreas carcinoma cells. All examined pancreatic carcinoma cells expressed CXCL-8 and TNFRII mRNA constitutively in RPMI-1640 medium without FBS. TNF-alpha, LIF, IL-1beta, IL-6, IL-8, or IFN-beta enhanced the expression of CXCL-8 mRNA, but IL-10 did not in Hs-700T cells. Actinomycin D suppressed and cycloheximide augmented CXCL-8 mRNA which was induced by TNF-alpha or not. The half-life of CXCL-8 mRNA was 36.5 min by TNF-alpha and 35.2 min by no stimulation. In our previous study, LIF promoted cell growth in Hs-700T cells. LIF induced CXCL-8 mRNA in a dose- and time-dependent manner. Addition of recombinant CXCL-8 did not induce cell growth of Hs-700T. Anti-CXCL-8 IgG significantly suppressed cell growth. CXCL-8 would act as an autocrine growth factor in Hs-700T cells, which expressed CXCL-8 mRNA highly without stimulation. Curcumin (diferuloylmethane), NF-kappaB inhibitor, suppressed cell proliferation in Hs-700T cells. These results suggest that CXCL-8 plays a pivotal role in progression of pancreatic cancer, and its expression is influenced by inflammatory cytokines in pancreatic tumor microenvironment.     

Crosstalk between Desmoglein 2 and Patched 1 accelerates chemical-induced skin tumorigenesis

Aberrant activation of Hedgehog (Hh) signaling is causative of BCCs and has been associated with a fraction of SCCs. Desmoglein 2 (Dsg2) is an adhesion protein that is upregulated in many cancers and overexpression of Dsg2 in the epidermis renders mice more susceptible to squamous-derived neoplasia. Here we examined a potential crosstalk between Dsg2 and Hh signaling in skin tumorigenesis. Our findings show that Dsg2 modulates Gli1 expression, in vitro and in vivo. Ectopic expression of Dsg2 on Ptc1^+/lacZ background enhanced epidermal proliferation and interfollicular activation of the Hh pathway. Furthermore, in response to DMBA/TPA, the Dsg2/Ptc1^+/lacZ mice developed squamous lessons earlier than the WT, Ptc1^+/lacZ, and Inv-Dsg2 littermates. Additionally, DMBA/TPA induced BCC formation in all mice harboring the Ptc1^+/lacZ gene and the presence of Dsg2 in Dsg2/Ptc1^+/lacZ mice doubled the BCC tumor burden. Reporter analysis revealed activation of the Hh pathway in the BCC tumors. However, in the SCCs we observed Hh activity only in the underlying dermis of the tumors. Furthermore, Dsg2/Ptc1^+/lacZ mice demonstrated enhanced MEK/Erk1/2 activation within the tumors and expression of Shh in the dermis. In summary, our results demonstrate that Dsg2 modulates Hh signaling, and this synergy may accelerate skin tumor development by different mechanisms.