Molecular mechanisms in C-Phycocyanin induced apoptosis in human chronic myeloid leukemia cell line-K562

Jagu Subhashini, Suraneni V.K. Mahipal, Madhava C. Reddy, Metukuri Mallikarjuna Reddy, Aparna Rachamallu, Pallu Reddanna

Research output: Contribution to journalArticlepeer-review

Abstract

C-Phycocyanin (C-PC), the major light harvesting biliprotein from Spirulina platensis is of greater importance because of its various biological and pharmacological properties. It is a water soluble, non-toxic fluorescent protein pigment with potent anti-oxidant, anti-inflammatory and anti-cancer properties. In the present study the effect of highly purified C-PC was tested on growth and multiplication of human chronic myeloid leukemia cell line (K562). The results indicate significant decrease (49%) in the proliferation of K562 cells treated with 50 μM C-PC up to 48 h. Further studies involving fluorescence and electron microscope revealed characteristic apoptotic features like cell shrinkage, membrane blebbing and nuclear condensation. Agarose electrophoresis of genomic DNA of cells treated with C-PC showed fragmentation pattern typical for apoptotic cells. Flow cytometric analysis of cells treated with 25 and 50 μM C-PC for 48 h showed 14.11 and 20.93% cells in sub-G0/G1 phase, respectively. C-PC treatment of K562 cells also resulted in release of cytochrome c into the cytosol and poly(ADP) ribose polymerase (PARP) cleavage. These studies also showed down regulation of anti-apoptotic Bcl-2 but without any changes in pro-apoptotic Bax and thereby tilting the Bcl-2/Bax ratio towards apoptosis. These effects of C-PC appear to be mediated through entry of C-PC into the cytosol by an unknown mechanism. The present study thus demonstrates that C-PC induces apoptosis in K562 cells by cytochrome c release from mitochondria into the cytosol, PARP cleavage and down regulation of Bcl-2.

Original languageEnglish (US)
Pages (from-to)453-462
Number of pages10
JournalBiochemical Pharmacology
Volume68
Issue number3
DOIs
StatePublished - Aug 1 2004

Keywords

  • Apoptosis
  • Bcl-2
  • C-PC
  • C-Phycocyanin
  • CML
  • COX
  • Cytochrome c
  • FACS
  • K562 human chronic myeloid leukemia cell line
  • PARP
  • chronic myeloid leukemia
  • cyclooxygenase
  • fluorescence activated cell sorter

ASJC Scopus subject areas

  • Biochemistry
  • Pharmacology

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