Simultaneous production of parathyroid hormone-related protein (PTHrP) and granulocyte colony-stimulating factor (G-CSF) in lung cancer patients with hypercalcemia and leukocytosis

Abstract

Hypercalcemia and leukocytosis are often associated with primary lung cancer as a paraneoplastic syndrome. Recently, parathyroid hormone-related protein (PTHrP) and granulocyte colony stimulating factor (G-CSF) have been identified as major causative peptides for hypercalcemia and leukocytosis, respectively. We studied four men with advanced primary lung cancer (stages from IIIA to IV) who presented with hypercalcemia (corrected serum calcium levels: 10.5 mg/dl) and leukocytosis (WBC > 10,000 per mm3). The age of the patients ranged from 59 to 79 years old. The pathological subtypes were squamous cell carcinoma in three and adenocarcinoma in one. The mean serum calcium levels and leukocyte counts were 15.8 +/- 1.4 mg/dl (mean +/- SE) and 24,800 +/- 3,253 cells/mm3 (mean +/- SE), respectively. Abnormally high serum levels of PTHrP and G-CSF were found in three patients (mean +/- SE: 137 +/- 68 pg/ml; normal range in human serum, < 16 pg/ml), and in all four (mean +/- SE: 72 +/- 7.7 pg/ml; normal range in human serum, < 20 pg/ml), respectively. Immuno-histochemical examination of cancerous tissue obtained from these patients showed positive staining for both PTHrP and G-CSF within the cytoplasm of all the cancerous tissue. These results suggest that the association of hypercalcemia and leukocytosis in patients with advanced primary lung cancer is caused by production of both PTHrP and G-CSF by cancerous tissue.