Statin immunolocalization in human brain tumors. Detection of noncycling cells using a novel marker of cell quiescence.

Surgical specimens of 35 human brain tumors were examined with a novel monoclonal antibody, S-44, immunoreactive to statin, a nuclear protein specifically expressed in quiescent (noncycling) G0-phase cells. Benign tumors typically were statin positive with labeling indices (LI) between 22% and 96%: acoustic schwannomas (n = 3, mean = 29.9 +/- 19.4%); meningiomas (n = 4, mean = 59.0 +/- 15.1%); pituitary adenomas (n = 3, mean = 79.9 +/- 28.2%), and an epidermoid cyst (41.0%). By contrast, the statin LI of 18 of 24 (75%) malignant brain tumors was less than or equal to 2%: medulloblastomas (n = 7, mean = 0.3 +/- 0.2%); anaplastic astrocytomas (n = 3, mean = 1.6 +/- 2.7%); glioblastomas (n = 10, mean = 10.3 +/- 14.4%); metastatic carcinomas (n = 3, mean = 3.0 +/- 4.6); and a germinoma (0.2%). The vascular endothelium among diverse tumors typically was statin positive. All 21 tumors with a statin LI less than 10% were malignant, and all nine tumors with a statin LI greater than 40% were benign. The statin LI of benign tumors (n = 11, mean = 55.1 +/- 26.7%) was significantly higher than that of the malignant tumors (n = 24, mean = 5.2 +/- 10.5%, P less than 0.001). The absence of statin expression is a new way to determine the malignancy of human brain tumors. The statin LI may be useful to guide the prognosis and treatment of individual patients. The mechanisms that control statin expression are important in therapy seeking to shift the proliferating, cycling cells to the quiescent, G0 compartment.