Smoothelin is a specific and robust marker for distinction of muscularis propria and muscularis mucosae in the gastrointestinal tract.
OBJECTIVE
As tumour specimens and biopsy specimens become smaller, recognition of anatomical structures relevant for staging is increasingly challenging. So far no marker is known that reliably discriminates between muscularis propria (MP) and muscularis mucosae (MM) of the gastrointestinal tract. Recently, smoothelin expression has been shown to differ in MP and MM of the urinary bladder. We aimed to analyse the expression of smoothelin in the gastrointestinal tract in MP and MM in order to define a novel diagnostic tool to identify MM bundles.


RESULTS
The expression of smoothelin was analysed immunohistochemically in comparison with alpha-smooth muscle actin (alpha-SMA) in specimens from colon, stomach and oesophagus (n = 107). In contrast to alpha-SMA, which equally stained MM and MP, absent or significantly weaker smoothelin expression was found in MM was found, which was particularly valid in colon and gastric specimens.


CONCLUSIONS
The combination of smoothelin and SMA represents a robust marker to discriminate MM from MP in the gastrointestinal tract.
Montani
Matteo
M
Institut für Klinische Pathologie, UniversitätsSpital Zürich, Schmelzbergstrasse 12, Zürich, Switzerland. matteo.montani@usz.ch
Thiesler
Thore
T
Kristiansen
Glen
G
D000199:Actins / Q000378:metabolism; D015415:Biomarkers / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000378:metabolism; D003106:Colon / Q000033:anatomy & histology / Q000378:metabolism / Q000473:pathology; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D003598:Cytoskeletal Proteins / Q000378:metabolism*; D004938:Esophageal Neoplasms / Q000378:metabolism / Q000473:pathology; D004947:Esophagus / Q000033:anatomy & histology / Q000378:metabolism / Q000473:pathology; D005753:Gastric Mucosa / Q000378:metabolism; D041981:Gastrointestinal Tract / Q000033:anatomy & histology / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D009092:Mucous Membrane / Q000033:anatomy & histology / Q000378:metabolism / Q000473:pathology; D009124:Muscle Proteins / Q000378:metabolism*; D013270:Stomach / Q000033:anatomy & histology / Q000473:pathology; D013274:Stomach Neoplasms / Q000378:metabolism / Q000473:pathology
C541116:ACTA2 protein, human; D000199:Actins; D015415:Biomarkers; D014408:Biomarkers, Tumor; D003598:Cytoskeletal Proteins; D009124:Muscle Proteins; C100762:SMTN protein, human