Stable overexpression of specific segments of the P2P-R protein in human MCF-7 cells promotes camptothecin-induced apoptosis

J Cell Physiol. 2003 Dec;197(3):445-52. doi: 10.1002/jcp.10381.


The stable overexpression of near full-length P2P-R protein in human Saos 2 cells restricts cell cycle progression by inducing mitotic arrest at prometaphase and mitotic apoptosis (Gao and Scott, 2002). Those effects of P2P-R were observed in Saos-2 cells that lack p53 and employ a caspase-3-dependent apoptotic signaling pathway. The current studies were performed to evaluate if overexpression of specific segments of the P2P-R protein promote apoptosis in human MCF-7 cells that contain p53 and employ a different apoptotic signaling pathway. Since segments of P2P-R were found not to induce apoptosis independently, the ability of three different P2P-R segments to promote camptothecin-induced apoptosis was evaluated following their stable transfection and expression in MCF-7 cells. Relative to full-length P2P-R (1-1560 aa), the three P2P-R segments used in these studies included: P2P-R-2 (761-1560 aa), P2P-R-3 (1156-1560 aa), and P2P-R-4 (1314-1560 aa). The results document that overexpression of P2P-R-2 and P2P-R-3 promotes camptothecin-induced apoptosis by three to fivefold when assayed by flow cytometric analysis of apoptotic sub 2n cell populations or by TUNEL assays. In contrast, P2P-R-4 had no effect on apoptosis. These results suggest that the ability of P2P-R to promote camptothecin-induced apoptosis in MCF-7 cells involves a specific region (1156-1314 aa) that exists within P2P-R. The data presented also show that the p53 binding domain of P2P-R overlaps with the apoptosis-associated region and previous studies documented that this region of P2P-R also binds single-strand nucleotides (Witte and Scott, 1997). Therefore, P2P-R-promoted apoptosis induced by camptothecin may be influenced by such interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antineoplastic Agents, Phytogenic / pharmacology
  • Apoptosis / drug effects
  • Apoptosis / physiology*
  • Binding Sites / drug effects
  • Binding Sites / physiology
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / metabolism*
  • Breast Neoplasms / pathology
  • Camptothecin / pharmacology*
  • Carrier Proteins*
  • Cell Cycle / drug effects
  • Cell Cycle / physiology*
  • Enzyme Inhibitors / pharmacology
  • Humans
  • Mice
  • NIH 3T3 Cells
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism*
  • Peptide Fragments / pharmacology
  • Protein Structure, Tertiary / drug effects
  • Protein Structure, Tertiary / physiology
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*
  • Tumor Cells, Cultured
  • Tumor Suppressor Protein p53 / metabolism


  • Antineoplastic Agents, Phytogenic
  • Carrier Proteins
  • Enzyme Inhibitors
  • PRKRA protein, human
  • Peptide Fragments
  • RNA-Binding Proteins
  • Rbbp6 protein, mouse
  • Tumor Suppressor Protein p53
  • Camptothecin