IMMUNOHISTOCHEMICAL AND IMMUNORADIOMETRIC EVALUATIONS OF TOTAL CATHEPSIN-D IN HUMAN LARYNX

By using a commercially available immunoradiometric technique (Cath-D- IRMA, Cis BioInt.) the distribution of total cathepsin D (cath-D) in 3 0 malignant and in the corresponding histologically-proven non-maligna nt fragments obtained from lymph node negative patients suffering from larynx cancer was investigated. In both tissues the oestrogen and pro gesterone receptors were also assayed. In 17 out of the 30 samples, th e cath-D was also assayed by immunohistochemistry using the M1G8, a mo use monoclonal antibody raised against cath-D (Cis BioInt.). Our data indicate that cath-D is present in prismatic cells of the normal laryn geal epithelium and in the cancerous cells. In cancerous larynx, the o uter cell layer of large tumour nests showed the highest degree of imm unoreactivity, while fibroblasts and inflammatory cells always showed a very faint staining. Cathepsin D levels were significantly higher (P < 0.0001) in the cancerous fragments (with a mean of 33 +/- 3.4 pmol/ mg protein) than in the corresponding non-cancerous specimen (with a m ean of 20.8 +/- 2 pmol/mg protein). A significant positive association (P < 0.001) between cath-D and progesterone receptor (PR) concentrati on values in the cancerous larynx was observed; accordingly, tumours e xpressing PR had significantly (P = 0.0005) higher cath-D levels than the tumours which did not contain the receptor. In contrast, such a re lationship was absent in the non-malignant specimens. As regard the oe strogen receptor, no significant relationship between this and cath-D was observed. We conclude that cath-D measured by IRMA in tissue cytos ols is mainly derived from cancerous cells, the contribution from fibr oblasts and inflammatory cells being negligible. Cathepsin D overexpre ssion and association with the PR in the malignant part of the larynx could indicate a possible role of the receptor in the biology of this disease.