EVALUATION OF BIOLOGICAL CHARACTERISTICS OF LUNG-CANCER BY THE HUMAN 28 KDA VITAMIN-D-DEPENDENT CALCIUM-BINDING PROTEIN, CALBINDIN-D(28K)

We evaluated the biological characteristics of lung cancer by measurin g their contents of human 28 kDa vitamin D-dependent calcium binding p rotein (calbindin-D). Calbindin-D concentrations were determined in tu mor tissue and normal lung tissue extracts from patients with lung can cer by enzyme immunoassay. The percentage of high calbindin-D containi ng tissues in small cell lung cancer (SCLC) was significantly higher t han that in non-small cell lung cancer (NSCLC) and the calbindin-D con centration was low in normal lung extracts. In addition, most of the N SCLC which had a significantly high level of calbindin-D were at the a dvanced cancer stage with lymph node metastasis. Calbindin-D concentra tions were also determined in lung cancer cell lines. The percentage o f high calbindin-D containing cell lines was high in classic type SCLC , followed in order by variant type SCLC and NSCLC. In addition, in or der to examine the usefulness of calbindin-D as a marker of neuroendoc rine properties of lung cancer, we compared the sensitivity and specif icity of calbindin-D for distinguishing classic from variant type SCLC with neuron-specific enolase (NSE) and aromatic L-amino acid decarbox ylase (AADC) by relative operating characteristic curves. The diagnost ic accuracy of AADC was the highest of the three and that of calbindin -D was as high as that of NSE. These findings suggest calbindin-D to b e related to the neuroendocrine properties of lung cancer.