EXPRESSION OF THE EXTRACELLULAR-MATRIX PROTEIN TENASCIN IN MALIGNANT AND BENIGN OVARIAN-TUMORS

The extracellular matrix protein tenascin (TN) is overexpressed in a n umber of solid tumours. This, however, is the first study to examine T N expression in ovarian tumours. TN protein was examined in frozen sec tions of 50 human ovarian tumours by immunohistochemistry. Malignant a nd borderline tumours showed a significantly greater incidence and int ensity of stromal staining than benign tumours (P < 0.0001 and P = 0.0 38 respectively). Seven omental metastases were also examined and show ed a strikingly similar protein distribution to their primary tumour c ounterparts. The expression pattern of different RNA isoforms, created by alternative splicing of the primary transcript, was identified usi ng reverse transcription-polymerase chain reactions (RT-PCR). The smal lest TN RNA splice variant (284 bp) was found in all tumours examined, while the appearance of larger molecular weight transcripts (similar to 490 and 556 bp), as major forms, was predominantly limited to malig nant tumours, with 9/12 malignant tumours showing this pattern compare d with 1/6 benign tumours. These data suggest that malignant ovarian t umours have increased expression of TN compared with benign tumours an d this may be associated with induction of specific isoforms.