Identification of circadian-related gene expression profiles in entrained breast cancer cell lines

ABSTRACT

Cancer cells have broken circadian clocks when compared to their normal tissue counterparts. Moreover, it has been shown in breast cancer that disruption of common circadian oscillations is associated with a more negative prognosis. Numerous studies, focused on canonical circadian genes in breast cancer cell lines, have suggested that there are no mRNA circadian-like oscillations. Nevertheless, cancer cell lines have not been extensively characterized and it is unknown to what extent the circadian oscillations are disrupted. We have chosen representative non-cancerous and cancerous breast cell lines (MCF-10A, MCF-7, ZR-75-30, MDA-MB-231 and HCC-1954) in order to determine the degree to which the circadian clock is damaged. We used serum shock to synchronize the circadian clocks in culture. Our aim was to initially observe the time course of gene expression using cDNA microarrays in the non-cancerous MCF-10A and the cancerous MCF-7 cells for screening and then to characterize specific genes in other cell lines. We used a cosine function to select highly correlated profiles. Some of the identified genes were validated by quantitative polymerase chain reaction (qPCR) and further evaluated in the other breast cancer cell lines. Interestingly, we observed that breast cancer and non-cancerous cultured cells are able to generate specific circadian expression profiles in response to the serum shock. The rhythmic genes, suggested via microarray and measured in each particular subtype, suggest that each breast cancer cell type responds differently to the circadian synchronization. Future results could identify circadian-like genes that are altered in breast cancer and non-cancerous cells, which can be used to propose novel treatments. Breast cell lines are potential models for in vitro studies of circadian clocks and clock-controlled pathways.

KEYWORDS:

• Breast cancer
• circadian
• DNA microarrays
• mRNA expression
• serum shock

Declaration of interest statement

The authors report no conflict of interest with the work provided herein. The authors would like to thank Victor Issa for his technical support with denaturing agarose gel electrophoresis and Guy Cardineau for English revision. MAG expresses his gratitude to the Mexican National Council for Science and Technology (CONACyT) for the PhD grant scholarship #269963. This work was funded by Apoyo Complementario para Investigadores en Proceso de Consolidación Nivel I del S.N.I. 2009 from CONACyT Grant #117935 to SPS, and Catedras de Hematologia y Cancer and Terapia Celular from Tecnológico de Monterrey. The data discussed in this publication have been deposited in NCBI’s Gene Expression Omnibus (Edgar et al., 2002) and are accessible through GEO Series accession number GSE76370 (http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE76370). GSE76368 is for the MCF-7 data and GSE76369 for the MCF-10A data.

Supplementary material available online

Supplemental data for this article can be accessed at www.tandfonline.com/icbi.