Pancreatic cancer remains one of the deadliest human cancers despite current advances in conventional therapeutics including surgery and adjuvant therapies. Here, we showed that LZ1, a peptide derived from a snake venom cathelicidin, significantly inhibited growth of pancreatic cancer cells by inducing autophagy-dependent cell death both in vitro and in vivo. The LZ1-induced cell death was blocked by pharmacological or genetic inhibition of autophagy. In orthotopic model of pancreatic cancer, systemic administration of LZ1 (1-4 mg/kg) exhibited remarkable antitumor efficacy, significantly prolonged mice survival, and showed negligible adverse effects by comparison with gemcitabine (20 mg/kg). Mechanistic studies revealed that LZ1 acts through binding to nucleolin, whose expression on cell surface is frequently increased in pancreatic cancer cells. LZ1 binding triggers degradation of surface-expressed nucleolin. This leads to activation of 5'-AMP kinase which results in suppression of mTORC1 activity and induction of autophagic flux. These data suggest that LZ1, targeting nucleolin-AMPK-autophagy axis, is a promising lead for the development of therapeutic agents against pancreatic cancer.