The somatostatin analogue TT-232 induces apoptosis in A431 cells: sustained activation of stress-activated kinases and inhibition of signalling to extracellular signal-regulated kinases

Cell Signal. 2001 Oct;13(10):717-25. doi: 10.1016/s0898-6568(01)00194-2.


TT-232 is a somatostatin analogue containing a five-residue ring structure. The present report describes TT-232-induced signalling events in A431 cells, where a 4-h preincubation with the peptide irreversibly induced a cell death program, which involves DNA-laddering and the appearance of shrunken nuclei, but is unrelated to somatostatin signalling. Early intracellular signals of TT-232 include a transient two-fold activation of the extracellular signal-regulated kinase (ERK2) and a strong and sustained activation of the stress-activated protein kinases c-Jun NH(2)-terminal kinase (JNK)/SAPK and p38MAPK. Blocking the signalling to ERK or p38MAPK activation had no effect on the TT-232-induced cell killing. At the commitment time for inducing cell death, TT-232 decreased EGFR-tyrosine phosphorylation and prevented epidermial growth factor (EGF)-induced events like cRaf-1 and ERK2 activation. Signalling to ERK activation by FCS, phorbol 12-myristate 13-acetate (PMA) and platelet-derived growth factor (PDGF) was similarly blocked. Our data suggest that TT-232 triggers an apoptotic type of cell death, concomitant with a strong activation of JNK and a blockade of cellular ERK2 activation pathways.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Apoptosis*
  • Drug Antagonism
  • Epidermal Growth Factor / pharmacology
  • Humans
  • Kinetics
  • MAP Kinase Signaling System / drug effects*
  • Mitogen-Activated Protein Kinase 1 / metabolism
  • Mitogen-Activated Protein Kinase 8
  • Mitogen-Activated Protein Kinases / antagonists & inhibitors*
  • Mitogen-Activated Protein Kinases / metabolism*
  • Neoplasms / enzymology
  • Neoplasms / pathology
  • Peptides, Cyclic / pharmacology*
  • Somatostatin / pharmacology
  • Tumor Cells, Cultured
  • p38 Mitogen-Activated Protein Kinases


  • Antineoplastic Agents
  • Peptides, Cyclic
  • TT2-32
  • Somatostatin
  • Epidermal Growth Factor
  • Mitogen-Activated Protein Kinase 1
  • Mitogen-Activated Protein Kinase 8
  • Mitogen-Activated Protein Kinases
  • p38 Mitogen-Activated Protein Kinases