Lung cancer cell lines: Useless artifacts or invaluable tools for medical science?

Abstract

Multiple cell lines (estimated at 300-400) have been established from human small cell (SCLC) and non-small cell lung cancers (NSCLC). These cell lines have been widely dispersed to and used by the scientific community worldwide, with over 8000 citations resulting from their study. However, there remains considerable skepticism on the part of the scientific community as to the validity of research resulting from their use. These questions center around the genomic instability of cultured cells, lack of differentiation of cultured cells and absence of stromal-vascular-inflammatory cell compartments. In this report we discuss the advantages and disadvantages of the use of cell lines, address the issues of instability and lack of differentiation. Perhaps the most important finding is that every important, recurrent genetic and epigenetic change including gene mutations, deletions, amplifications, translocations and methylation-induced gene silencing found in tumors has been identified in cell lines and vice versa. These "driver mutations" represented in cell lines offer opportunities for biological characterization and application to translational research. Another potential shortcoming of cell lines is the difficulty of studying multistage pathogenesis in vitro. To overcome this problem, we have developed cultures from central and peripheral airways that serve as models for the multistage pathogenesis of tumors arising in these two very different compartments. Finally the issue of cell line contamination must be addressed and safeguarded against. A full understanding of the advantages and shortcomings of cell lines is required for the investigator to derive the maximum benefit from their use.

Fig. 1

Malignant transformation phenotype of p53 RNAi and K-RAS^V12 expressing HBEC3 cells. (Panel A) Contact inhibition is reduced in p53 RNAi and K-RAS^V12 expressing HBEC3 cells. Cells in vector control (top left) form smooth single layer cells at saturation density, p53 RNAi cells (top right) or K-RAS^V12 cells (bottom left) have partially lost contact inhibition and have overcrowded areas, and cells with p53 RNAi/K-RAS^V12 (bottom right) have lost contact inhibition and cells pile up forming many foci. (Panel B) Anchorage independent growth is increased considerably in p53 RNAi and K-RAS^V12 expressing HBEC3 cells. 1000 cells were grown in soft agar in the presence of EGF (5 ng/ml) and colonies were counted after 2 weeks. The numbers of colonies formed are increased 6, 11 and 23 fold in p53 RNAi, K-RAS^V12 and p53 RNAi/K-RAS^V12 expressing HBEC3 cells respectively compared with the vector control. (Panel C) Growth factor dependency is reduced in p53 RNAi and K-RAS^V12 expressing HBEC3 cells. 200 cells were cultured in KSFM medium in the presence (top, 5ng/ml)or absence of EGF (bottom) and colonies were stained with methylene blue after 2 weeks. Similar number of colonies formed in the presence of EGF in all cells (top), the colony number dramatically reduced in the absence of EGF in vector control (bottom left). (PanelD) Quantitation of colonies counted in bottom panel C. The number of colonies formed increased 4, 8 and 9-fold in p53 RNAi, K-RAS^V12 and p53 RNAi/K-RAS^V12 expressing HBEC3 cells respectively compared with the vector control. Figure modified from our previously published work [77].