Tumor cells, especially in a malignant form, proliferate rapidly that blood supply within the tumors becomes limited, leading to a condition of insufficient oxygen supply. Such hypoxic condition is known to impair the viability of cancer cells, but it can also be a factor to facilitate the appearance of cells with a higher degree of malignancy. Indeed, the hypoxic condition created within malignant tumors may contribute to promoting their aggressive behaviors, including tumor invasion and metastasis, and to the development of resistance to various therapeutic modalities such as chemotherapy. Recently, microRNAs, a group of short RNA fragments consisting of 18 to 20 nucleotides, have been shown to participate in regulating genes important for cell survival, differentiation and apoptosis. Since their discovery, modulation of these microRNAs has been a focus of intensive studies with regard to their significance on gene regulation and various aspects of cell biology. In this study, we investigated hypoxia-induced alterations in microRNAs in oral squamous cell carcinoma (OSCC) cells and discussed consequential gene modulation and relevant cellular responses.

Ⅰ. Introduction
 Ⅱ. Materials and Methods
  Cell culture and treatment
  RNA preparation
  miRNA expression array
  Data analysis and statistics
  Target prediction
 Ⅲ. Results
  miRNA expression profiles in OSCC cells
  Identification of predicted gene targets ofdifferentially expressed miRNAs
 Ⅳ. Discussion
 Ⅴ. References

• 이지혜(The Picower Institute for Learning & Memory, Massachusetts Institute of Technology) | Ji Hye Lee correspondence