Two-dimensional electrophoresis of proteins in tumours of the lung

The proteins of solid lung tumours (15 adenocarcinomas and 10 squamous cell carcinomas) were examined by high resolution two-dimensional electrophoresis (2-DE) and compared with the proteins of adjacent lung tissue which demonstrated no histological evidence of malignant transformation, and with the proteins of other malignant tumours and normal tissues. To investigate tumour cell-specific protein synthesis, we isolated malignant and normal cells enzymatically with collagenase, elastase, and DNase. Tissue and tumour cells were enriched in an additional step on a Percoll gradient. The 2-DE gel patterns derived from entire tissue and enriched tissue cell preparations were compared. No specific differences were found between the 2-DE protein patterns from adenocarcinomas and squamous cell carcinomas of the lung, but three proteins identified on the 2-DE gels appeared to be tumour-associated. Spot A is present in non-neoplastic and neoplastic epithelial tissues. Spot B is pronounced in 2-DE gels of sarcomas, but is also present in preparations of other malignant tissues. Spot C is present in all malignant cell preparations. These three spots were also demonstrated in 2-DE protein patterns from tissue cultures of malignant cell lines. Spot B and spot C were also present in some normal tissues.