The present invention relates to a soluble peptide comprising the amino acids sequence: KRFYVVMWKK (SEQ ID NO: 1) or a function-conservative variant thereof for use in the treatment of cancer. The invention also relates to a pharmaceutical composition for use in the treatment of cancer comprising at least one soluble peptide according to the invention or at least one acid nucleic according to the invention or at least one expression vector according to the invention, or at least one host cell according to the invention and a pharmaceutically acceptable carrier.