Whether the heterogeneity in tumor cell morphology and behavior is the consequence of a progressive accumulation of genetic alterations or an intrinsic property of cancer-initiating cells established at initiation remains controversial. The hypothesis of biological predetermination in human cancer was proposed many years ago and states that the biological potency of cancer cells is predestinated in the precancerous stage. The present study aimed to investigate whether the aberrant molecular events occurring in initial cancer stages could eventually influence colorectal cancer (CRC) progression. We analyzed the mRNA and miRNA expression profiles of colorectal normal mucosa, low-grade intraepithelial neoplasia (LIN), high-grade intraepithelial neoplasia (HIN), and adenocarcinoma tissues. Compared with the transitions from LIN to HIN to invasive carcinoma, the transition from normal epithelium to LIN appeared to be associated with greater changes in the number and expression levels of mRNAs and miRNAs, with a differential expression of 2322 mRNAs and 71 miRNAs detected. Utilizing these early molecular changes, a miRNA-hub network analysis showed that 166 genes were identified as targets regulated by 30 miRNAs. Among these genes, a 55-gene signature regulated by 5 miRNAs was shown to be associated with overall survival or disease-free survival in three independent sample sets. Thus, the molecular changes in the transcriptome associated with the transition from normal to intraepithelial neoplasm may influence CRC progression.
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