The results of our study suggest that DDC rs12666409A>T may be useful markers for predicting the clinical outcomes of patients with SCLC undergoing chemotherapy.
SCCL is known to undergo a process of dedifferentiation to a variant (drug-resistant) form, and this process is associated with loss of marker enzymes such as neuron-specific enolase (NSE) and dopa decarboxylase (DDC).
Retinoic acid incubation caused a reproducible decrease in c-myc expression in variant SCLC cells, but was not noted to increase L-dopa decarboxylase, an enzyme which biochemically distinguishes classic from variant SCLC cell lines.
Both cell lines show SCLC differentiations; neurosecretory granules were present and the SCLC related hormones dopa-decarboxylase and creatine kinase were elevated.
After multiple passages, UMC-SCLC-1 gradually changed its culture characteristics to a cell line, UMC-SCLC-1A, with morphological features of large cell anaplastic carcinoma, an altered growth pattern, decrease in calcitonin, and increase in radioresistance but retained the other biochemical markers of classic SCLC (bombesin and dopa decarboxylase production).