A therapeutic agent for cancer, particularly a cancer cell growth inhibitor, a cancer metastasis inhibitor or preventive agent, a drug using the agent, a method for determining the effect of cancer treatment, a method for predicting the prognosis of cancer treatment, cancer Of a method for screening a substance having an inhibitory effect on the growth of cancer and a method for screening a substance having an action of inhibiting metastasis of cancer. A pharmaceutical comprising a nucleic acid comprising a nucleotide sequence having at least 70% sequence identity with SEQ ID NO: 1 or 2 and exhibiting protein expression inhibitory activity. [Selection] Figure 3【課題】癌の治療剤、特に癌の細胞増殖抑制剤、癌の転移抑制又は予防剤、前記剤を利用した医薬、癌治療の効果を判定する方法、癌治療の予後を予測する方法、癌の増殖抑制作用を有する物質のスクリーニング方法、及び癌の転移阻害作用を有する物質のスクリーニング方法の提供。【解決手段】少なくとも配列番号１又は２と７０％以上の配列同一性を有するヌクレオチド配列から成る核酸であって、タンパク質発現抑制活性を示す核酸を含有する医薬。【選択図】図３
