Authors: Katoh, Y.; Katoh, M.

Source: Current Molecular Medicine, Volume 9, Number 7, September 2009 , pp. 873-886(14)

Publisher: Bentham Science Publishers

Abstract:

Hedgehog signaling is aberrantly activated in glioma, medulloblastoma, basal cell carcinoma, lung cancer, esophageal cancer, gastric cancer, pancreatic cancer, breast cancer, and other tumors. Hedgehog signals activate GLI family members via Smoothened. RTK signaling potentiates GLI activity through PI3KAKT- mediated GSK3 inactivation or RAS-STIL1-mediated SUFU inactivation, while GPCR signaling to Gs represses GLI activity through adenylate cyclase-mediated PKA activation. GLI activators bind to GACCACCCA motif to regulate transcription of GLI1, PTCH1, PTCH2, HHIP1, MYCN, CCND1, CCND2, BCL2, CFLAR, FOXF1, FOXL1, PRDM1 (BLIMP1), JAG2, GREM1, and Follistatin. Hedgehog signals are finetuned based on positive feedback loop via GLI1 and negative feedback loop via PTCH1, PTCH2, and HHIP1. Excessive positive feedback or collapsed negative feedback of Hedgehog signaling due to epigenetic or genetic alterations leads to carcinogenesis. Hedgehog signals induce cellular proliferation through upregulation of N-Myc, Cyclin D/E, and FOXM1. Hedgehog signals directly upregulate JAG2, indirectly upregulate mesenchymal BMP4 via FOXF1 or FOXL1, and also upregulate WNT2B and WNT5A. Hedgehog signals induce stem cell markers BMI1, LGR5, CD44 and CD133 based on cross-talk with WNT and/or other signals. Hedgehog signals upregulate BCL2 and CFLAR to promote cellular survival, SNAI1 (Snail), SNAI2 (Slug), ZEB1, ZEB2 (SIP1), TWIST2, and FOXC2 to promote epithelial-to-mesenchymal transition, and PTHLH (PTHrP) to promote osteolytic bone metastasis. KAAD-cyclopamine, Mu-SSKYQ-cyclopamine, IPI-269609, SANT1, SANT2, CUR61414 and HhAntag are small-molecule inhibitors targeted to Smoothened, GANT58, GANT61 to GLI1 and GLI2, and Robotnikinin to SHH. Hedgehog signaling inhibitors should be used in combination with RTK inhibitors, GPCR modulators, and/or irradiation for cancer therapy.

Keywords: Hedgehog; WNT; Notch; FGF; TGF-β; self-renewal; invasion; peritoneal dissemination

Document Type: Research article

Publication date: 2009-09-01

More about this publication?

• Current Molecular Medicine is an interdisciplinary journal focused on providing the readership with current and comprehensive reviews on fundamental molecular mechanisms of disease pathogenesis, the development of molecular-diagnosis and/or novel approaches to rational treatment. The reviews should be of significant interest to basic researchers and clinical investigators in molecular medicine. Periodically the journal will invite guest editors to devote an issue on a basic research area that shows promise to advance our understanding of the molecular mechanism(s) of a disease or has potential for clinical applications.

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