Selective activation of TNFR1 and NF-κB inhibition by a novel biyouyanagin analogue promotes apoptosis in acute leukemia cells.
BACKGROUND
Acquired resistance towards apoptosis is a hallmark of cancer. Elimination of cells bearing activated oncogenes or stimulation of tumor suppressor mediators may provide a selection pressure to overcome resistance. KC-53 is a novel biyouyanagin analogue known to elicit strong anti-inflammatory and anti-viral activity. The current study was designed to evaluate the anticancer efficacy and molecular mechanisms of KC-53 against human cancer cells.


METHODS
Using the MTT assay we examined initially how KC-53 affects the proliferation rates of thirteen representative human cancer cell lines in comparison to normal peripheral blood mononuclear cells (PBMCs) and immortalized cell lines. To decipher the key molecular events underlying its mode of action we selected the human promyelocytic leukemia HL-60 and the acute lymphocytic leukemia CCRF/CEM cell lines that were found to be the most sensitive to the antiproliferative effects of KC-53.


RESULTS
KC-53 promoted rapidly and irreversibly apoptosis in both leukemia cell lines at relatively low concentrations. Apoptosis was characterized by an increase in membrane-associated TNFR1, activation of Caspase-8 and proteolytic inactivation of the death domain kinase RIP1 indicating that KC-53 induced mainly the extrinsic/death receptor apoptotic pathway. Regardless, induction of the intrinsic/mitochondrial pathway was also achieved by Caspase-8 processing of Bid, activation of Caspase-9 and increased translocation of AIF to the nucleus. FADD protein knockdown restored HL-60 and CCRF/CEM cell viability and completely blocked KC-53-induced apoptosis. Furthermore, KC-53 administration dramatically inhibited TNFα-induced serine phosphorylation on TRAF2 and on IκBα hindering therefore p65/NF-κΒ translocation to nucleus. Reduced transcriptional expression of pro-inflammatory and pro-survival p65 target genes, confirmed that the agent functionally inhibited the transcriptional activity of p65.


CONCLUSIONS
Our findings demonstrate, for the first time, the selective anticancer properties of KC-53 towards leukemic cell lines and provide a detailed understanding of the molecular events underlying its dual anti-proliferative and pro-apoptotic properties. These results provide new insights into the development of innovative and targeted therapies for the treatment of some forms of leukemia.
Department of Biological Sciences, University of Cyprus, Kallipoleos 75, Nicosia, 01678, Cyprus.
Christiana G
CG
Savva
Department of Chemistry, BioScience Research Collaborative, Rice University, 6500 Main Street, Houston, TX, 77005, USA.
Sotirios
S
Totokotsopoulos
Department of Chemistry, BioScience Research Collaborative, Rice University, 6500 Main Street, Houston, TX, 77005, USA.
Kyriakos C
KC
Nicolaou
Department of Biological Sciences, University of Cyprus, Kallipoleos 75, Nicosia, 01678, Cyprus.
Christiana M
CM
Neophytou
Department of Biological Sciences, University of Cyprus, Kallipoleos 75, Nicosia, 01678, Cyprus. andreasc@ucy.ac.cy.
Andreas I
AI
Constantinou
D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D018922:HL-60 Cells; D006801:Humans; D007938:Leukemia / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D007963:Leukocytes, Mononuclear / Q000187:drug effects / Q000473:pathology; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics; D016328:NF-kappa B / Q000096:biosynthesis / Q000235:genetics; D009363:Neoplasm Proteins / Q000096:biosynthesis* / Q000235:genetics; D010766:Phosphorylation; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000096:biosynthesis / Q000235:genetics; D012717:Sesquiterpenes / Q000008:administration & dosage* / Q000737:chemistry; D015398:Signal Transduction / Q000187:drug effects; D013141:Spiro Compounds / Q000008:administration & dosage* / Q000737:chemistry
D016328:NF-kappa B; D009363:Neoplasm Proteins; D047888:Receptors, Tumor Necrosis Factor, Type I; D012717:Sesquiterpenes; D013141:Spiro Compounds; C509583:biyouyanagin A
Apoptosis; Biyouyanagin; Caspases; Death receptors; Leukemia; NF-κΒ; Nuclear factor κΒ; TNFR1; Tumor necrosis factor receptor 1