Targeting colorectal cancer stem cells with inducible caspase-9.
Colorectal cancer stem cells (CSCs) drive tumor growth and are suggested to initiate distant metastases. Moreover, colon CSCs are reportedly more resistant to conventional chemotherapy, which is in part due to upregulation of anti-apoptotic Bcl-2 family members. To determine whether we could circumvent this apoptotic blockade, we made use of an inducible active caspase-9 (iCasp9) construct to target CSCs. Dimerization of iCasp9 with AP20187 in HCT116 colorectal cancer cells resulted in massive and rapid induction of apoptosis. In contrast to fluorouracil (5-FU)-induced apoptosis, iCasp9-induced apoptosis was independent of the mitochondrial pathway as evidenced by Bax/Bak double deficient HCT116 cells. Dimerizer treatment of colon CSCs transduced with iCasp9 (CSC-iCasp9) also rapidly induced high levels of apoptosis, while these cells were unresponsive to 5-FU in vitro. More importantly, injection of the dimerizer into mice that developed a colon CSC-iCasp9-induced tumor resulted in a strong decrease in tumor size, an increase in tumor cell apoptosis and a clear loss of CD133(+) CSCs. Taken together, our data indicate that dimerization of iCasp9 circumvents the apoptosis block in CSCs, which results in effective tumor regression in vivo.
Laboratory for Experimental Oncology and Radiobiology, Centre for Molecular Medicine, Academic Medical Centre, Amsterdam, The Netherlands.
Kristel
K
Kemper
Hans
H
Rodermond
Selçuk
S
Colak
Catarina
C
Grandela
Jan Paul
JP
Medema
D000818:Animals; D000964:Antimetabolites, Antineoplastic / Q000494:pharmacology / Q000627:therapeutic use; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D053453:Caspase 9 / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D049109:Cell Proliferation; D015179:Colorectal Neoplasms / Q000201:enzymology / Q000473:pathology*; D004789:Enzyme Activation; D005472:Fluorouracil / Q000494:pharmacology; D005786:Gene Expression Regulation; D045325:HCT116 Cells; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D058990:Molecular Targeted Therapy; D014411:Neoplastic Stem Cells / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D055503:Protein Multimerization / Q000187:drug effects; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D018874:Spheroids, Cellular / Q000473:pathology; D016559:Tacrolimus / Q000031:analogs & derivatives / Q000494:pharmacology / Q000627:therapeutic use; D047368:Tumor Burden; D023041:Xenograft Model Antitumor Assays
C463061:AP20187; D000964:Antimetabolites, Antineoplastic; D051017:Apoptosis Regulatory Proteins; D011994:Recombinant Proteins; C499320:PARP1 protein, human; D000071137:Poly (ADP-Ribose) Polymerase-1; D011065:Poly(ADP-ribose) Polymerases; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D005472:Fluorouracil; D016559:Tacrolimus