Detection of Specific mRNAs in Culture Medium Conditioned by Human Tumour Cells: Potential for New Class of Cancer Biomarkers in Serum.

BACKGROUND

This study aimed to develop and optimise procedures to enable us to establish, in a well-controlled environment, if cancer cells routinely secrete gene transcripts potentially suitable for monitoring as biomarkers.

MATERIALS AND METHODS

Aliquots of the conditioned media (CM) exposed to cancer cells (including breast, lung and nasal cancer cell lines) were removed at intervals of 24 hours over a 96-hour time period and were passed through 0.45 μm or 0.22 μm filters, to remove cellular material. Methods for subsequent RNA extraction (from CM and cells) were investigated. RT-PCR was performed for a number of mRNAs, including mdr-1, mrp-1, CK-19, HnRNP B1, GST-π, topoisomerase II, bcl-2 and β-actin.

RESULTS

Gene transcripts, amplifiable by RT-PCR, were detected in conditioned media from all human cancer cell lines studied. This RNA did not result from the presence of cells in the conditioned media and, as expected, was absent from control medium not exposed to tumour cells.

CONCLUSION

The results from this study indicate that gene transcripts may be secreted from human cancer cells and are detectable in the subsequent cell-free media. The methods developed and optimised here may be suitable for analysis of mRNAs as biomarkers in serum/plasma from cancer patients.