COX-2 expression in striated muscle under physiological conditions.
OBJECTIVE
The role of cyclooxygenase-2 (COX-2) in disease has been extensively studied, (Annu Rev Med (2002) 53:35; N Engl J Med (2001) 345:433) but less information is available with respect to possible physiological functions of COX-2. Information on how and where COX-2 is expressed under physiological conditions may increase our understanding of its physiological role. Previous studies have revealed a COX-2 dependent production of prostanoids under physiological conditions, without entirely determining the source of this production.


METHODS
To assess COX-2 expression under normal conditions, we analyzed tissue specimens that were removed from 30 healthy study subjects in conjunction with surgical procedure related to insertion of dental implants and from three patients which had muscle tissue from Quadriceps femoris muscle removed as part of surgical treatment of soft tissue sarcomas not directly affecting the muscle tissue. Immunohistochemistry and immunoblotting (Western blotting) was used to assess the presence of COX-2 protein.


RESULTS
In 25 of 30 patients (83%), COX-2 protein was expressed in striated muscle, as assessed by immunohistochemistry. All cases had COX-2 expression verified by Western blotting. In none of the 25 subjects with COX-2 expression did we notice concomitant inflammation of the adjacent submucosal tissue.


CONCLUSIONS
It is a novel finding that COX-2 is expressed in striated muscle under physiological conditions. COX-2 activity in striated muscle is a possible explanation for the hitherto unknown localization of prostanoids synthesis under physiological conditions.
Sudbø
J
J
Department of Medical Oncology, The Norwegian Radium Hospital, Montebello, Oslo, Norway. jon.sudbo@rh.uio.no
Reith
A
A
Flørenes
V A
VA
Nesland
J M
JM
Ristimäki
A
A
Bryne
M
M
D000293:Adolescent; D000328:Adult; D000368:Aged; D015153:Blotting, Western; D051546:Cyclooxygenase 2; D005152:Facial Muscles / Q000201:enzymology; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000032:analysis* / Q000502:physiology; D008297:Male; D008565:Membrane Proteins; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000201:enzymology*; D010544:Peroxidases / Q000032:analysis* / Q000502:physiology; D011451:Prostaglandin-Endoperoxide Synthases / Q000032:analysis* / Q000502:physiology; D011453:Prostaglandins / Q000096:biosynthesis; D013848:Thigh
D007527:Isoenzymes; D008565:Membrane Proteins; D011453:Prostaglandins; D010544:Peroxidases; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases