MicroRNA expression, survival, and response to interferon in liver cancer

Abstract

Background: Hepatocellular carcinoma is a common and aggressive cancer that occurs mainly in men. We examined microRNA expression patterns, survival, and response to interferon alfa in both men and women with the disease.

Methods: We analyzed three independent cohorts that included a total of 455 patients with hepatocellular carcinoma who had undergone radical tumor resection between 1999 and 2003. MicroRNA-expression profiling was performed in a cohort of 241 patients with hepatocellular carcinoma to identify tumor-related microRNAs and determine their association with survival in men and women. In addition, to validate our findings, we used quantitative reverse-transcriptase-polymerase-chain-reaction assays to measure microRNAs and assess their association with survival and response to therapy with interferon alfa in 214 patients from two independent, prospective, randomized, controlled trials of adjuvant interferon therapy.

Results: In patients with hepatocellular carcinoma, the expression of miR-26a and miR-26b in nontumor liver tissue was higher in women than in men. Tumors had reduced levels of miR-26 expression, as compared with paired noncancerous tissues, which indicated that the level of miR-26 expression was also associated with hepatocellular carcinoma. Moreover, tumors with reduced miR-26 expression had a distinct transcriptomic pattern, and analyses of gene networks revealed that activation of signaling pathways between nuclear factor kappaB and interleukin-6 might play a role in tumor development. Patients whose tumors had low miR-26 expression had shorter overall survival but a better response to interferon therapy than did patients whose tumors had high expression of the microRNA.

Conclusions: The expression patterns of microRNAs in liver tissue differ between men and women with hepatocellular carcinoma. The miR-26 expression status of such patients is associated with survival and response to adjuvant therapy with interferon alfa.

2009 Massachusetts Medical Society

Figures

Figure 1. Expression of miR-26 in Hepatic Tumors and Noncancerous Tissue in Men and Women

Panel A shows miR-26a-1 expression in noncancerous hepatic tissue from 30 women and 194 men, as determined by microarray analysis with the use of an unpaired t-test. Panel B shows miR-26a expression in noncancerous hepatic tissue obtained from 26 women and 56 age-matched men, as determined by quantitative reverse-transcriptase–polymerase-chain-reaction assay with the use of an unpaired t-test. In Panels A and B, the horizontal lines in the box plots represent the median, the boxes represent the interquartile range, and the whiskers represent the 2.5th and 97.5th percentiles. Panel C shows comparisons of relative levels of miR-26a-1 expression in paired tumor and nontumor samples from 224 patients, according to miR-26 status, with the use of paired t-tests. The data in Panels A through C are log2 relative expression levels, normalized to the values in disease-free samples from eight control subjects. Panel D shows survival according to the level of miR-26a-1 expression in tumor samples, as determined by microarray analysis, with the use of the log-rank test. The median expression level was used as the cutoff. Reduced miR-26 expression in 106 patients was classified as the lower 50th percentile (with a mean reduction in tumor tissue, as compared with nontumor tissue, by a factor of 2.69). High miR-26 expression in 111 patients was classified as the upper 50th percentile (with a mean reduction in tumor tissue, as compared with nontumor tissue, by a factor of 0.98).

Figure 2. Distinct Transcriptional Activities in Hepatocellular Carcinomas with Low miR-26 Expression

Panel A shows a multidimensional scaling plot, based on the expression of 11,580 genes, for 224 patients with hepatocellular carcinoma. The level of miR-26 expression was dichotomized on the basis of the median value as low (blue) or high (red). Panel B shows the activation of gene networks of signaling between nuclear factor κB (NF-κB) and interleukin-6 (IL6) in tumors with low miR-26 expression. Colored ovals represent up-regulated genes in tumors with low miR-26 expression, and open ovals represent genes that are not on the list of significant genes but are reported to be associated with the network. The open ovals that are labeled as NF-κB, Iκb, and IKK represent molecular nodes related to protein complexes of NF-κB, inhibitor of NF-κB, and Iκb kinase, respectively. The open oval labeled as 5 = HT (5-hydroxytryptamine) represents a chemical node related to serotonin receptor signaling, as categorized by pathway analysis software (Ingenuity). Arrows represent positive regulation of gene expression, with solid arrows indicating direct regulation, and broken arrows indirect regulation.

Figure 3. Association between miR-26a Expression in Tumors and Overall Survival in Two Trials of Interferon Alfa

Panels A and B show the association between miR-26a expression and overall survival in patients with hepatocellular carcinoma from two control groups (cohort 2 in Panel A and cohort 3 in Panel B). In cohort 2, 24 patients had high miR-26a expression and 35 patients had low miR-26a expression. In cohort 3, 21 patients had high miR-26a expression and 19 patients had low miR-26a expression. Panels C and D show the association between adjuvant therapy with interferon alfa and overall survival in patients with tumors with low miR-26a expression. In cohort 2, there were 24 patients in the group that received interferon alfa and 35 patients in the control group. In cohort 3, there were 20 patients in the group that received interferon alfa and 19 patients in the control group. Panels E and F show the association between adjuvant therapy with interferon alfa and overall survival in patients with tumors that had high miR-26a expression. In cohort 2, there were 35 patients in the group that received interferon alfa and 24 patients in the control group. In cohort 3, there were 19 patients in the group that received interferon alfa and 21 patients in the control group.