Ca(2+) channel properties in neuroendocrine tumor cell cultures investigated by whole-cell patch-clamp technique.

Abstract

Neuroendocrine tumor (NET) cells of the gastroenteropancreatic system express a variety of voltage-operated Ca(2+) channels (VOCCs). In addition, NET cells release hormones and biogenic amines in distinct patterns, leading to typical hypersecretion syndromes. Interestingly, these patterns depend on the primary location of the NET. The aim of this study was to investigate a possible link between clinically distinct entities of NETs and specific properties of VOCCs. Using whole-cell patch-clamp technique, electrophysiological data were obtained from permanent NET cell cultures as well as from primary cultivated NET cells from foregut and midgut tumors. Definite Ca(2+) channel characteristics were analyzed by a color-coding method. As a result, we could demonstrate specific Ca(2+) channel characteristics in NET cells from midgut tumors that were not found in NET cells from a foregut location. This may be important functionally with respect to different cell biological functions of NET cells. In summary, clear differences exist in the VOCC pattern in NET cells from foregut versus midgut. This may be functionally relevant in the hypersecretion syndrome predominantly found in foregut NETs. Therefore, these data on the characteristics of VOCCs could be useful in the development of a novel therapy for NET disease; for example, specific VOCC subtype modulators may help.