Differential expression of platelet‐derived growth factor and transforming growth factor genes in small‐ and non‐small‐cell human lung carcinoma lines

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Abstract
We have investigated a panel of human lung cancer cell lines representing the major groups of lung cancer, i.e., small‐cell carcinoma (SCC) and the group of non‐SCC, consisting of squamous‐cell carcinoma (SQC), adenocarcinoma (ADC) and large‐cell carcinoma (LCC), for their expression of certain growth factor genes. Messenger RNA from each cell line was hybridized with probes for platelet‐derived growth factor (PDGF) A‐ and B‐chains, insulin‐like growth factor (IGF)‐I and ‐II, transforming growth factor (TGF)‐α and β, epidermal growth factor (EGF) as well as a probe for the EGF receptor. All non‐SCC cell lines examined showed expression of the PDGF A‐chain gene. The PDGF B‐chain and TGF‐β gene were expressed in all non‐SCC cell lines but one, H‐125 (ADC). TGF‐α gene expression was demonstrated in the SQC cell line U‐1752, in both ADC cell lines (H‐23 and H‐125) and in one of the 3 LCC cell lines, U‐1810. IGF‐II was only transcribed in the LCC cell line U‐1810. The EGF‐receptor was detected in all non‐SCC cell lines but one, H‐661 (LCC). Neither IGF‐I nor EGF transcripts could be seen in any of the 10 cell lines examined. In contrast to the non‐SCC cell lines, the 4 SCC lines were constantly negative for the probes employed in this study. The frequent and heterogeneous expression of growth factor transcripts in all non‐SCC studied, but not SCC‐cell lines, may contribute to the difference in biological behaviour observed in vivo and in vitro between the 2 major lung cancer entities.