Advances in the understanding of cancer cell biology and response to drug 
treatment have benefited from new molecular technologies and methods for 
integrating information from multiple sources. The NCI-60, a panel of 60 diverse 
human cancer cell lines, has been used by the National Cancer Institute to 
screen >100,000 chemical compounds and natural product extracts for anticancer 
activity. The NCI-60 has also been profiled for mRNA and protein expression, 
mutational status, chromosomal aberrations, and DNA copy number, generating an 
unparalleled public resource for integrated chemogenomic studies. Recently, 
microRNAs have been shown to target particular sets of mRNAs, thereby preventing 
translation or accelerating mRNA turnover. To complement the existing NCI-60 
data sets, we have measured expression levels of microRNAs in the NCI-60 and 
incorporated the resulting data into the CellMiner program package for 
integrative analysis. Cell line groupings based on microRNA expression were 
generally consistent with tissue type and with cell line clustering based on 
mRNA expression. However, mRNA expression seemed to be somewhat more informative 
for discriminating among tissue types than was microRNA expression. In addition, 
we found that there does not seem to be a significant correlation between 
microRNA expression patterns and those of known target transcripts. Comparison 
of microRNA expression patterns and compound potency patterns showed significant 
correlations, suggesting that microRNAs may play a role in chemoresistance. 
Combined with gene expression and other biological data using multivariate 
analysis, microRNA expression profiles may provide a critical link for 
understanding mechanisms involved in chemosensitivity and chemoresistance.