Human Parafollicular Cancer Cells: A Neuronal Model for Novel Drug Identification to Treat Neuropathic Pain.

Objectives: This study was conducted to identify the types of functional voltage‐gated calcium channels expressed by the neuronal‐like human parafollicular (CA77) cancer cell line. Methods: CA77 cells were grown in culture and the expression of functional calcium channels studied using Fura‐2 am during live cell imaging to measure changes in intracellular calcium levels in response to stimulation with potassium chloride (KCl) alone and in combination with several voltage‐gated calcium channel blockers. These included: nifedipine, funnel spider toxin (FTX), and ω‐conotoxin, which inhibit L‐type, P/Q‐type, and N‐type voltage‐gated calcium channels, respectively. To investigate transcriptional expression, primers for L‐, N‐, and P/Q‐type channels were used in reverse transcriptase polymerase chain reaction (RT‐PCR). Results: Significant increases in intracellular calcium levels were measured in response to KCl (P <. 001, n = 45), which was not repressed by nifedipine or ω‐conotoxin (P =. 893, n = 34, P =. 957, n = 31). However, KCl‐mediated intracellular calcium increase was repressed by FTX (P <. 001, n = 42). Using RT‐PCR, mRNA for P/Q‐type receptor was detectable but not the mRNA for the N‐ and L‐type voltage‐gated channels. Conclusions: Taken together, our results provide evidence that CA77 cells express functional P/Q (CaV2.1) calcium channels, which are known to promote increased neuronal excitability, inflammation, and nociception. Thus, CA77 cells can provide an efficient and cost‐effective means to screen novel therapeutics to treat migraine and other neurological diseases of the head and neck that involve P/Q channel activation in the underlying pathology. [ABSTRACT FROM AUTHOR]