GHRH antagonist causes DNA damage leading to p21 mediated cell cycle arrest and apoptosis in human colon cancer cells

Florian Hohla, Stefan Buchholz, Andrew V. Schally, Stefan Seitz, Ferenc G. Rick, Luca Szalontay, Jozsef L. Varga, Marta Zarandi, Gabor Halmos, Irving Vidaurre, Awtar K. Ganju-Krishan, Metin Kurtoglu, Sudhir Chandna, Elmar Aigner, Christian Datz

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


We investigated the mechanisms of inhibitory effect of growth hormone-releasing hormone (GHRH) antagonist JMR-132 on the growth of HT29, HCT-116 and HCT-15 human colon cancer cells in vitro and in vivo. High-affinity binding sites for GHRH and mRNA for GHRH and splice variant-1 (SV1) of the GHRH receptor were found in all three cell lines tested. Proliferation of HT-29, HCT-116 and HCT-15 cells was significantly inhibited in vitro by JMR-132. Time course studies revealed that the treatment of human HCt-116 colon cancer cells with 10 M GHRH antagonist JMR-132 causes a significant DNA damage as shown by an increase in olive tail moment (OtM) and loss of inner mitochondrial membrane potential (Δψm). Western blotting demonstrated a time-dependent increase in protein levels of phospho-p53 (Ser46), Bax, cleaved caspase-9, -3, cleavage of poly(ADp-ribose)polymerase (pARp) and a decrease in Bcl-2 levels. An augmentation in cell cycle checkpoint protein p21Waf1/CipI was accompanied by a cell cycle arrest in S-phase. DNA fragmentation visualized by the comet assay and the number of apoptotic cells increased time dependently as determined by flow cytometric annexinV and pI staining assays. In vivo, JMR-132 decreased the volume of Ht-29, HCt-116 and HCt-15 tumors xenografted into athymic mice up to 75% (p < 0.05) and extended tumor doubling time (p < 0.001). Our observations suggest that GHRH antagonist JMR-132 exerts its antiproliferative effect on experimental colon cancer cells through p21 Waf1/CipI mediated S-phase arrest along with apoptosis involving the intrinsic pathway.

Original languageEnglish (US)
Pages (from-to)3149-3156
Number of pages8
JournalCell Cycle
Issue number19
StatePublished - Oct 1 2009


  • Apoptosis
  • Cell cycle arrest
  • Colon cancer
  • DNA damage
  • GHRH antagonist
  • Mitochondrial membrane potential
  • p21

ASJC Scopus subject areas

  • Cell Biology
  • Molecular Biology
  • Developmental Biology


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