Cancer is a leading cause of death worldwide, outnumbering deaths from cardiovascular diseases and cerebrovascular diseases. An attack rate of cancer has increased in accordance with economic growth and changes of disease forms caused by changes in lifestyle and dietary patterns, causing about 7.6 million deaths from cancer and 12.66 million new cases of cancer to appear in 2008, which demonstrates the continuous increase in cancer occurrence and deaths from cancer. In accordance with societal developments, populations continue to become older, and therefore the burden of cancer occurrence is predicted to increase more. Also, while an attack rate of cancer has also gradually increased among young people due to genetic causes and stress, and thus the prevention and treatment of cancer is more important than ever before, innovative treatments for cancer, such as development of anti-cancer agents having superior effects without side effects, have not been available, and therefore development of such treatments is strongly desired in the art.
Among such treatments, a method by which proliferation of tumors and cancer cells can be inhibited by limiting a supply of oxygen and nutrients is known, and efforts to develop technology related thereto are active. For this purpose, expression of factors among genes of tumors and cancer cells expressed under a hypoxia condition that are involved in glucose metabolism and generation of new blood vessels, and their mechanisms of adapting to a surrounding micro-environment are important in understanding growth and proliferation of tumors and cancer cells.
On the other hand, microRNA is small non-coding RNA which inhibits gene expression at a control step after transcription. MicroRNA is composed of 18 to 25 nucleotides on average and forms a hairpin structure. It complementarily binds to a 3′-UTR portion of the sequence of a target gene to inhibit mRNA from decomposing or translating to a protein, and it has been known that at least about 5000 human genes are targets of microRNA. Functions of microRNA in vivo can be various, and for instance, include cell differentiation and proliferation, control of developmental stages and metabolism, angiogenesis, and apoptosis, depending on what type of target gene is eventually controlled. As such, importance of the functions of microRNA is increasing, and accordingly, related research is becoming more active.
An appearance of expression of modified microRNA has been reported in various cancers, and its involvement in controlling cancer-stimulating genes or cancer-inhibiting genes is being discovered. In addition, it was proved that microRNA controls a step of forming new blood vessels, and a possibility of developing a novel treatment method for inhibiting blood vessel diseases and cancer using such mechanism is suggested. What is desperately required is the development of a drug for preventing cancer in an early stage of cancer cell formation and for treating cancer by inhibiting angiogenesis induced in cancer through the mechanism of controlling expression of cancer-related genes of microRNA.