Hedgehog signaling in normal urothelial cells and in urothelial carcinoma cell lines.
Constitutive activation of hedgehog signaling, often caused by PTCH1 inactivation and leading to inappropriate activation of GLI target genes, is crucial for the development of several human tumors including basal cell carcinoma of the skin and medulloblastoma. The PTCH1 gene at 9q22 is also considered as a candidate tumor suppressor in transitional cell carcinoma (TCC), of which >50% show LOH in this region. However, only rare mutations have been found in PTCH1. We have therefore investigated GLI-dependent promoter activity and expression of hedgehog pathway components in TCC cell lines and proliferating normal urothelial cells. Normal urothelial cells cultured in serum-free medium, but not TCC lines exhibited low, but significant promoter activity under standard growth conditions. Accordingly, GLI1-3 and PTCH1 mRNAs were expressed at moderate levels, and sonic hedgehog (SHH) mRNA expression was low to undetectable. In co-transfection experiments GLI1 increased promoter activity significantly in one TCC line and further in normal urothelial cells, but less strongly in other TCC lines. Expression patterns of GLI factor mRNAs did not correlate with inducibility. No significant effects of SHH or cyclopamine on proliferation were observed, ruling out autocrine effects. However, SHH induced GLI-dependent promoter activity in normal urothelial cells. Taken together, our data suggest that the hedgehog pathway is weakly active in normal adult urothelial cells and of limited importance in TCC.
Thievessen
Ingo
I
Urologische Klinik, Heinrich-Heine-Universität, Düsseldorf, Germany.
Wolter
Marietta
M
Prior
Andrea
A
Seifert
Hans-Helge
HH
Schulz
Wolfgang A
WA
D002295:Carcinoma, Transitional Cell / Q000378:metabolism* / Q000503:physiopathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects / Q000502:physiology*; D016147:Genes, Tumor Suppressor; D053823:Hedgehog Proteins; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D001749:Urinary Bladder Neoplasms / Q000378:metabolism* / Q000503:physiopathology; D019459:Urothelium / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D014704:Veratrum Alkaloids / Q000494:pharmacology; D000071676:Zinc Finger Protein GLI1
C400551:GLI1 protein, human; D053823:Hedgehog Proteins; D008565:Membrane Proteins; C000606236:PTCH1 protein, human; D000072079:Patched Receptors; D000072081:Patched-1 Receptor; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; C509239:SHH protein, human; D015534:Trans-Activators; D014157:Transcription Factors; D014704:Veratrum Alkaloids; D000071676:Zinc Finger Protein GLI1; C000541:cyclopamine