Detection of canonical hedgehog signaling in breast cancer by 131-iodine-labeled derivatives of the sonic hedgehog protein

Nanomolar, Noncovalent Antagonism of Hedgehog Cholesterolysis: Exception to the "Irreversibility Rule" for Protein Autoprocessing Inhibition

Hedgehog (Hh) signaling ligands undergo carboxy terminal sterylation through specialized autoprocessing, called cholesterolysis. Sterylation is brought about intramolecularly in a single turnover by an adjacent enzymatic domain, called HhC, which is found in precursor Hh proteins only. Previous attempts to identify antagonists of the intramolecular activity of HhC have yielded inhibitors that bind HhC irreversibly through covalent mechanisms, as is common for protein autoprocessing inhibitors. Here, we report an exception to the "irreversibility rule" for autoprocessing inhibition. Using a fluorescence resonance energy transfer-based activity assay for HhC, we screened a focused library of sterol-like analogues for noncovalent inhibitors and identified and validated four structurally related molecules, which were then used for structure-activity relationship studies. The most effective derivative, tBT-HBT, inhibits HhC noncovalently with an IC₅₀ of 300 nM. An allosteric binding site for tBT-HBT, encompassing residues from the two subdomains of HhC, is suggested by kinetic analysis, mutagenesis studies, and photoaffinity labeling. The inhibitors described here resemble a family of noncovalent, allosteric inducers of HhC paracatalysis which we have described previously. The inhibition and the induction appear to be mediated by a shared allosteric site on HhC.

Resveratrol Counteracts Hypoxia-Induced Gastric Cancer Invasion and EMT through Hedgehog Pathway Suppression

BACKGROUND

Gastric Cancer (GC) is one of the most malignant and lethal tumors worldwide. The hypoxic microenvironment is correlated with GC cell invasion, metastasis and Epithelial-Mesenchymal Transition (EMT). Resveratrol is a compound extracted from various plants, including grapes, berries, and some traditional Chinese medicines. Recently, the anticancer properties of resveratrol against many cancers have been reported in a range of studies. However, the exact mechanism through which resveratrol prevents GC invasion and metastasis under hypoxic conditions remains unclear.

OBJECTIVE

The objective of this study is to show to what extent resveratrol could inhibit the hypoxia-induced malignant biological behavior of GC.

METHODS

SGC-7901 cells were cultured in a consistent 3% O2 hypoxic condition or 21% O2 normal condition for 48 hours to establish an in vitro hypoxia model. Western blot and qRT-PCR were used to detect EMT markers of SGC- 7901 cells, including E-cadherin, HIF-1a, Vimentin, etc. Transwell Matrigel Invasion Assays were used to test the invasive ability of SGC-7901 cells. The siRNA targeting Gli-1 showed its role in hypoxia-induced EMT and invasion of SGC-7901 cells.

RESULTS

Resveratrol was found to significantly decrease HIF-1α protein levels induced by hypoxia in SGC-7901 cells. HIF-1α accumulation was found to promote cell proliferation, migration, and invasive capacities in addition to EMT changes through the activation of the Hedgehog pathway. These effects were found to be reversed by resveratrol.

CONCLUSION

Therefore, these data indicate that resveratrol may serve as a potential anticancer agent for the treatment of GC, even in a hypoxic tumor microenvironment.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

Protein Lipidation As a Regulator of Apoptotic Calcium Release: Relevance to Cancer

Calcium is a critical regulator of cell death pathways. One of the most proximal events leading to cell death is activation of plasma membrane and endoplasmic reticulum-resident calcium channels. A large body of evidence indicates that defects in this pathway contribute to cancer development. Although we have a thorough understanding of how downstream elevations in cytosolic and mitochondrial calcium contribute to cell death, it is much less clear how calcium channels are activated upstream of the apoptotic stimulus. Recently, it has been shown that protein lipidation is a potent regulator of apoptotic signaling. Although classically thought of as a static modification, rapid and reversible protein acylation has emerged as a new signaling paradigm relevant to many pathways, including calcium release and cell death. In this review, we will discuss the role of protein lipidation in regulating apoptotic calcium signaling with direct therapeutic relevance to cancer.

Transcriptomic comparison of primary bovine horn core carcinoma culture and parental tissue at early stage

Aim:

Squamous cell carcinoma or SCC of horn in bovines (bovine horn core carcinoma) frequently observed in Bos indicus affecting almost 1% of cattle population. Freshly isolated primary epithelial cells may be closely related to the malignant epithelial cells of the tumor. Comparison of gene expression in between horn’s SCC tissue and its early passage primary culture using next generation sequencing was the aim of this study.

Materials and Methods:

Whole transcriptome sequencing of horn’s SCC tissue and its early passage cells using Ion Torrent PGM were done. Comparative expression and analysis of different genes and pathways related to cancer and biological processes associated with malignancy, proliferating capacity, differentiation, apoptosis, senescence, adhesion, cohesion, migration, invasion, angiogenesis, and metabolic pathways were identified.

Results:

Up-regulated genes in SCC of horn’s early passage cells were involved in transporter activity, catalytic activity, nucleic acid binding transcription factor activity, biogenesis, cellular processes, biological regulation and localization and the down-regulated genes mainly were involved in focal adhesion, extracellular matrix receptor interaction and spliceosome activity.

Conclusion:

The experiment revealed similar transcriptomic nature of horn’s SCC tissue and its early passage cells.

Hedgehog Cholesterolysis: Specialized Gatekeeper to Oncogenic Signaling

Discussions of therapeutic suppression of hedgehog (Hh) signaling almost exclusively focus on receptor antagonism; however, hedgehog's biosynthesis represents a unique and potentially targetable aspect of this oncogenic signaling pathway. Here, we review a key biosynthetic step called cholesterolysis from the perspectives of structure/function and small molecule inhibition. Cholesterolysis, also called cholesteroylation, generates cholesterol-modified Hh ligand via autoprocessing of a hedgehog precursor protein. Post-translational modification by cholesterol appears to be restricted to proteins in the hedgehog family. The transformation is essential for Hh biological activity and upstream of signaling events. Despite its decisive role in generating ligand, cholesterolysis remains conspicuously unexplored as a therapeutic target.

The Potential Role of Hedgehog Signaling in the Luminal/Basal Phenotype of Breast Epithelia and in Breast Cancer Invasion and Metastasis

The epithelium of the lactiferous ducts in the breast is comprised of luminal epithelial cells and underlying basal myoepithelial cells. The regulation of cell fate and transit of cells between these two cell types remains poorly understood. This relationship becomes of greater importance when studying the subtypes of epithelial breast carcinoma, which are categorized according to their expression of luminal or basal markers. The epithelial mesenchymal transition (EMT) is a pivotal event in tumor invasion. It is important to understand mechanisms that regulate this process, which bears relation to the normal dynamic of epithelial/basal phenotype regulation in the mammary gland. Understanding this process could provide answers for the regulation of EMT in breast cancer, and thereby identify potential targets for therapy. Evidence points towards a role for hedgehog signaling in breast tissue homeostasis and also in mammary neoplasia. This review examines our current understanding of role of the hedgehog-signaling (Hh) pathway in breast epithelial cells both during breast development and homeostasis and to assess the potential misappropriation of Hh signals in breast neoplasia, cancer stem cells and tumor metastasis via EMT.

Patched targeting peptides for imaging and treatment of hedgehog positive breast tumors

High tumor hedgehog expression is correlated with poor prognosis in invasive ductal carcinoma. Peptides which bind the patched receptor have recently been reported to have a growth inhibitory effect in tumors with activated hedgehog signaling. We sought to examine growth inhibition with these peptides in breast cancer cells and use these peptides as molecular imaging probes to follow changes in hedgehog expression after chemotherapy. Significant growth inhibition was observed in breast cancer cell lines treated with PTCH-blocking peptides. Significant in vitro uptake was observed with both FITC- and ^99mTc-EC-peptide conjugates. In vivo imaging studies displayed greater accumulation of ^99mTc-labeled peptides within tumors as compared to adjacent muscle tissue. Patched receptor expression increased after treatment and this correlated with an increase in tumor radiotracer uptake. These studies suggest that peptides which bind the sonic hedgehog docking site in patched receptor correlate with patched expression and can be used to image patched in vivo. Further, our data suggest that radiolabeled peptides may enable us to examine the activity of the hedgehog signaling pathway and to evaluate response to anti-cancer therapies.

Heparanase-1 and components of the hedgehog signalling pathway are increased in untreated alveolar orbital rhabdomyosarcoma

BACKGROUND

To assess the activities of heparanase-1 and elements of the hedgehog signalling pathway in alveolar orbital rhabdomyosarcoma.

METHODS

Specimens (n = 23) were divided into two groups, those from patients with preoperative chemoradiotherapy or untreated patients; six samples of normal extraocular muscle were used as a normal muscle group. The presence of heparanase-1, patched, smoothened and glioma-associated oncogene homologue-1 protein expression was determined in 23 cases of archival paraffin-embedded alveolar orbital rhabdomyosarcoma after immunohistochemistry. RNA was extracted from three groups of paraffin-embedded specimens and messenger RNA expressions of heparanase-1, smoothened and glioma-associated oncogene homologue-1 compared using nested reverse transcriptase polymerase chain reaction and a limiting dilution analysis.

RESULTS

The heparanase-1, patched, smoothened and glioma-associated oncogene homologue-1 protein was expressed in 91.3%, 87.0%, 91.3% and 78.3%, respectively, of the alveolar orbital rhabdomyosarcoma specimens. Untreated rhabdomyosarcoma samples tended to stain intensely, but staining was relatively weak in tissue obtained from the chemoradiotherapy group. The expression levels of heparanase-1, smoothened and glioma-associated oncogene homologue-1 messenger RNA in untreated and chemoradiotherapy groups paralleled that seen with immunology, and there were no significant differences in heparanase-1, smoothened and glioma-associated oncogene homologue-1 messenger RNA levels between the chemoradiotherapy group and the normal muscle group (P > 0.05). However, the messenger RNA in the untreated group were all significantly higher than those in the chemoradiotherapy and normal muscle groups (P < 0.01).

CONCLUSIONS

Both heparanase-1 and hedgehog signalling pathway are involved in the pathogenesis of alveolar orbital rhabdomyosarcoma; however, chemotherapy and/or radiotherapy appears to significantly inhibit their upregulation.