Bone morphogenetic protein 4 induces differentiation of colorectal cancer stem cells and increases their response to chemotherapy in mice.
OBJECTIVE
The limited clinical response observed in many patients with colorectal cancer may be related to the presence of chemoresistant colorectal cancer stem cells (CRC-SCs). Bone morphogenetic protein 4 (BMP4) promotes the differentiation of normal colonic stem cells. We investigated whether BMP4 might be used to induce differentiation of CRC-SCs and for therapeutic purposes.


METHODS
CRC-SCs were isolated from 25 tumor samples based on expression of CD133 or using a selection culture medium. BMP4 expression and activity on CRC-SCs were evaluated in vitro; progeny of the stem cells were evaluated by immunofluorescence, immunoblot, and flow cytometry analyses. The potential therapeutic effect of BMP4 was assessed in immunocompromised mice after injection of CRC-SCs that responded to chemotherapy (n = 4) or that did not (n = 2).


RESULTS
CRC-SCs did not express BMP4 whereas differentiated cells did. Recombinant BMP4 promoted differentiation and apoptosis of CRC-SCs in 12 of 15 independent experiments; this effect did not depend on Small Mothers against decapentaplegic (Smad)4 expression level or microsatellite stability. BMP4 activated the canonical and noncanonical BMP signaling pathways, including phosphoInositide 3-kinase (PI3K) and PKB (protein kinase B)/AKT. Mutations in PI3K or loss of Phosphatase and Tensin homolog (PTEN) in Smad4-defective tumors made CRC-SCs unresponsive to BMP4. Administration of BMP4 to immunocompromised mice with tumors that arose from CRC-SCs increased the antitumor effects of 5-fluorouracil and oxaliplatin.


CONCLUSIONS
BMP4 promotes terminal differentiation, apoptosis, and chemosensitization of CRC-SCs in tumors that do not have simultaneous mutations in Smad4 and constitutive activation of PI3K. BMP4 might be developed as a therapeutic agent against cancer stem cells in advanced colorectal tumors.
Department of Surgical and Oncological Sciences, University of Palermo, Palermo, Italy.
Ylenia
Y
Lombardo
Alessandro
A
Scopelliti
Patrizia
P
Cammareri
Matilde
M
Todaro
Flora
F
Iovino
Lucia
L
Ricci-Vitiani
Gaspare
G
Gulotta
Francesco
F
Dieli
Ruggero
R
de Maria
Giorgio
G
Stassi
D000071916:AC133 Antigen; D011125:Adenomatous Polyposis Coli / Q000235:genetics / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D055415:Bone Morphogenetic Protein 4 / Q000494:pharmacology / Q000627:therapeutic use*; D002454:Cell Differentiation; D002478:Cells, Cultured; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000473:pathology; D005260:Female; D005472:Fluorouracil / Q000627:therapeutic use*; D006023:Glycoproteins / Q000378:metabolism; D006801:Humans; D008297:Male; D051379:Mice; D053842:Microsatellite Instability; D008875:Middle Aged; D009154:Mutation; D014411:Neoplastic Stem Cells / Q000187:drug effects*; D009944:Organoplatinum Compounds / Q000627:therapeutic use*; D000077150:Oxaliplatin; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D058539:Phosphatidylinositol 3-Kinase / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D051901:Smad4 Protein / Q000378:metabolism
D000071916:AC133 Antigen; D015703:Antigens, CD; D000970:Antineoplastic Agents; D055415:Bone Morphogenetic Protein 4; D006023:Glycoproteins; D009944:Organoplatinum Compounds; C000606023:PROM1 protein, human; D010455:Peptides; C000606024:Prom1 protein, mouse; C497796:SMAD4 protein, human; D051901:Smad4 Protein; C490810:Smad4 protein, mouse; D000077150:Oxaliplatin; D058539:Phosphatidylinositol 3-Kinase; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; C487757:Pten protein, mouse; D005472:Fluorouracil