MicroRNA profiling in cancer.

The diagnosis of cancer has undergone major changes in the last 40 years. Once based purely on morphology, diagnosis has come to incorporate immunological, cytogenetic and molecular methods. Many cancers, especially leukaemias, are now defined by molecular markers. Gene expression profiling based on mRNA has led to further refinement of the classification and diagnosis of cancer. More recently, miRNAs (microRNAs), among other small non-coding RNA molecules, have been discovered and found to be major players in cell biology. miRNAs, having both oncogenic and tumour-suppressive functions, are dysregulated in many types of cancer. miRNAs also interfere with metastasis, apoptosis and invasiveness of cancer cells. In the present review, we discuss recent advances in miRNA profiling in human cancer. We discuss both frequent and rare tumour types and give an outlook on future developments.