A frequent activated smoothened mutation in sporadic basal cell carcinomas

Ching Wan Lam, Jingwu Xie, Ka Fai To, Ho Keung Ng, Kam Cheong Lee, Nancy Wah Fun Yuen, Pak Leong Lim, Lisa Yuen Shan Chan, Sui Fan Tong, Frank McCormick

Research output: Contribution to journalArticle

144 Scopus citations


Basal-cell carcinomas (BCCs) are the most common cancer in Caucasians. It has been reported that the patched gene is inactivated in 30-40% sporadic BCCs and 20% sporadic medulloblastomas via loss of heterozygosity and nonsense mutations. Recently, two activating smoothened mutations have been found in the sporadic basal cell carcinomas. One, at base pair 1604 (G-to-T transversion) of exon 9, changes codon 535 from tryptophan to leucine, and the other, at base pair 1685 (G-to-A transition) of exon 10, changes codon 562 from arginine to glutamine. In our study, 1604G→T was found in 20 out of 97 (20.6%) sporadic BCCs. The high prevalence indicates that 1604G is the mutation hot spot in our tumor samples. This mutation was detected in all three histological subtypes of BCCs, suggesting that smoothened mutation is an early event during the development of the tumor. Our finding of a high smoothened mutation rate, together with high frequent patched gene mutations reported recently, indicates that activation of the hedgehog signal transduction pathway is the most common and early event in the development of sporadic BCCs. Additionally, to determine whether smoothened, like patched, is also involved in the carcinogenesis of medulloblastomas, we screened medulloblastoma samples for these two mutations by restriction analysis. We have found the 1604G→T mutation in 1 out of 21 medulloblastomas. This result confirmed smoothened gene involvement in the carcinogenesis of medulloblastoma.

Original languageEnglish (US)
Pages (from-to)833-836
Number of pages4
Issue number3
StatePublished - Jan 21 1999
Externally publishedYes


  • Basal cell carcinoma
  • Hedgehog
  • Mutation
  • Patched
  • Smoothened

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cancer Research

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  • Cite this

    Lam, C. W., Xie, J., To, K. F., Ng, H. K., Lee, K. C., Yuen, N. W. F., Lim, P. L., Chan, L. Y. S., Tong, S. F., & McCormick, F. (1999). A frequent activated smoothened mutation in sporadic basal cell carcinomas. Oncogene, 18(3), 833-836. https://doi.org/10.1038/sj.onc.1202360