Embryonic form of smooth muscle myosin heavy chain (SMemb/MHC-B) in gastrointestinal stromal tumor and interstitial cells of Cajal

Am J Pathol. 1999 Jan;154(1):23-8. doi: 10.1016/S0002-9440(10)65246-7.


Myosin heavy chain (MHC) isoform expression was evaluated by immunohistochemistry and reverse transcription polymerase chain reaction (RT-PCR) to clarify a possible link between gastrointestinal stromal tumor (GIST) and interstitial cells of Cajal (ICCs) in the gastrointestinal (GI) tract. Using monoclonal antibodies against MHC isoforms, 18 of 27 GISTs (67%) showed immunoreactivity for non-smooth-muscle myosin or the embryonic form of MHC (SMemb), but only one tumor showed immunoreactivity for smooth muscle cell (SMC)-specific isoforms (SM1 and SM2). Co-expression of KIT or CD34, which is also expressed in GIST and ICCs, was demonstrated in 18 (100%) and 16 SMemb-positive tumors (89%), respectively. Otherwise, the expression of SMemb in GIST was not correlated with the patient's age or sex, tumor size, histological grade of GIST, or expression of mesenchymal cell markers, such as alpha-smooth muscle actin (alpha-SMA) or S100 protein. By double-fluorescence immunostaining of the tunica muscularis of the GI tract wall, co-expression of KIT, CD34, and SMemb was demonstrated in ICCs, which were negative for SM1 and SM2. RT-PCR analysis confirmed that GIST expressed SMemb-mRNA, which lacked neuronal cell-specific inserts of 30 bp. These facts further strengthen the current hypothesis that GIST is a tumor of ICCs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Embryo, Mammalian / metabolism*
  • Female
  • Gastrointestinal Neoplasms / metabolism*
  • Gastrointestinal Neoplasms / pathology
  • Humans
  • Immunohistochemistry
  • Intestine, Small / innervation
  • Intestine, Small / metabolism*
  • Intestine, Small / pathology
  • Male
  • Middle Aged
  • Muscle, Smooth / embryology*
  • Myosin Heavy Chains / genetics
  • Myosin Heavy Chains / metabolism*
  • Neurons / metabolism
  • Stromal Cells / metabolism*
  • Stromal Cells / pathology
  • Transcription, Genetic / physiology


  • Myosin Heavy Chains