This is the second post on use of gene expression profiling for assessing chemotherapy response or success. Here researchers from America and Korea have used microRNA expression profiling to identify specific signatures associated with clinical resistance to cisplatin/fluorouracil (CF) chemotherapy for gastric cancer. Biopsy samples were collected prior to chemotherapy from 90 gastric cancer patients treated with CF and from 34 healthy volunteers. At the time of disease progression, post-treatment samples were additionally collected from 8 clinical responders. miRNA expression was determined using a custom-designed Agilent microarray. A miRNA signature distinguishing gastric cancer from normal stomach epithelium was identified. 30 miRNAs were significantly inversely correlated with time to progression whereas 28 miRNAs were significantly positively correlated with time to progression of 82 cancer patients (P<0.05). Prominent among the upregulated miRNAs associated with chemosensitivity were miRNAs known to regulate apoptosis, including let-7g, miR-342, miR-16, miR-181, miR-1, and miR-34. When this 58-miRNA predictor was applied to a separate set of pre- and post-treatment tumor samples from the 8 clinical responders, all of the 8 pre-treatment samples were correctly predicted as low-risk, whereas samples from the post-treatment tumors that developed chemoresistance were predicted to be in the high-risk category by the 58 miRNA signature, suggesting that selection for the expression of these miRNAs occurred as chemoresistance arose.
In summary these researchers have identified 1) a miRNA expression signature that distinguishes gastric cancer from normal stomach epithelium from healthy volunteers, and 2) a chemoreresistance miRNA expression signature that is correlated with time to progression after CF therapy.
[CLICK HERE TO READ THE ORIGINAL ARTICLE PUBLISHED IN BMC MEDICAL GENOMICS]
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