A peptide having eight amino acid sequences derived from cancer-associated gene (CAGE) is described which retains anticancer activity and activity to promote anticancer drug sensitivity of anticancer drug resistant cancer cells. Specifically, a peptide which has an amino acid sequence of SEQ ID NO: 1 (AQTGTGKT) and thus binds to the CAGE protein is disclosed, which inhibits an inter-linkage between CAGE and GSK3β, thus exhibiting anticancer activity and activity to promote anticancer drug sensitivity of anticancer drug resistant cancer cells. A pharmaceutical composition is also disclosed containing the peptide with the amino acid sequence of SEQ ID NO: 1 (AQTGTGKT), for anticancer use or anticancer drug aiding.