Aberrant expression and function of microRNAs (miRNAs) in cancer have added a new layer of complexity to the understanding of development and progression of the disease state. It has been demonstrated that miRNAs have a crucial function in oncogenesis by regulating cell proliferation and apoptosis as oncogenes or tumor suppressors. The expression signatures of miRNAs provide exciting opportunities in the diagnosis, prognosis and therapy of cancer. Since miRNAs can function as either oncogenes or tumor suppressor genes in oncogenesis, the potential of using these small RNAs as therapeutic targets opens up new opportunities for cancer therapy by either inhibiting or augmenting their activity.

Aberrant expression and function of microRNAs (miRNAs) in cancer have added a new layer of complexity to the understanding of development and progression of the disease state. It has been demonstrated that miRNAs have a crucial function in oncogenesis by regulating cell proliferation and apoptosis as oncogenes or tumor suppressors. The expression signatures of miRNAs provide exciting opportunities in the diagnosis, prognosis and therapy of cancer. Since miRNAs can function as either oncogenes or tumor suppressor genes in oncogenesis, the potential of using these small RNAs as therapeutic targets opens up new opportunities for cancer therapy by either inhibiting or augmenting their activity.

The concept of cancer stem cells has great clinical implications. This is due to the fact that small subpopulations of these cells have been identified in a variety of neoplastic conditions ranging from solid tumors to liquid malignancies. Although there are some huge gaps in our current understanding of the role played by cancer stem cells in cancer biology, a growing body of evidence provides strong support for the principal functions of these cells in tumorigenesis. This has represented the potential of cancer stem cells in the development of novel and innovative tools for the treatment of metastatic tumors. This book aims to offer a broad framework for obtaining insight into the state-of-the-art knowledge on cancer stem cell biology and highlight the therapeutic implications of these cells in the future of clinical oncology.