Published in Cancer Detection and Prevention 1994; 18(5):357-365.

Increased Levels of a 21-kDa protein in the Circulation of Tumor-Bearing Patients

Channa Shalitin, PhD¹, Ron Epelbaum, MD², Boaz Moskovitz, MD ³, Ruth Segal, BSC², Clari Valansi, BSc¹, Marina Werner, MD¹, Pinchas M Livne, MD³

Address all correspondence and reprint requests to: Dr. Channa Shalitin, Dept of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel

ABSTRACT: A novel non-ras 21-kDa protein (p21) was detected in sera of cancer patients by enzyme-linked immunosorbent assay (ELISA), using polyclonal anti-p2l antibodies. While only 4.6% of the healthy donors (n = 43) showed p2l serum levels higher than the mean ± 2 SD of the normal group, 33 to 80% of the cancer patients (n = 94) with various tumors were positive in the ELISA test. In particular, patients with malignant lymphoma, urogenital, and gastrointestinal tumors had a 2.8- to ninefold increase in p2l serum levels. Elevated serum levels were also found in patients with benign prostatic hyperplasia (3.2-fold increase). In 17 out of 22 patients with urogenital tumors, changes in serum p2l levels correlated with the clinical course of the disease. In 15 patients, a favorable response to therapy was correlated with a decline in serum p2l level. Two patients with renal cell carcinoma showed increased or persistently high levels of p2l after surgery and were subsequently found to have distant metastases. Expression of p2l in ten renal cell carcinoma tissues was determined by Western blotting. There was a trend toward a higher content of p2l in the less-differentiated tumor tissues. In conclusion, p2l may be a useful indicator in monitoring the outcome of treatment in patients with various malignant tumors. In patients with renal cell carcinoma, p2l serum levels may be of particular importance because no other tumor marker is available.

KEY WORDS: 21-kDa protein, benign prostate tumor, urogenital tumors, lymphoma, cancer.

http://www.cancerprev.org/Journal/Issues/18/5/40