TY - JOUR
T1 - Blockade of tumor cell transforming growth factor-βs enhances cell cycle progression and sensitizes human breast carcinoma cells to cytotoxic chemotherapy
AU - Ohmori, Tohru
AU - Yang, Jin Long
AU - Price, James O.
AU - Arteaga, Carlos L.
N1 - Funding Information:
This work was supported by NIH Grant R01 CA62212, Merit Review and Clinical Investigator grants from the Department of Veteran Affairs, Vanderbilt Cancer Center Support Grant CA68485, and the T. J. Martell Foundation. T.O. is a postdoctoral research fellow supported in part by the Markey Foundation.
PY - 1998/12/15
Y1 - 1998/12/15
N2 - We have examined the effect of neutralizing TGF-β antibodies on cisplatin-mediated cytotoxicity against MDA-231 human breast tumor cell spheroids. These tridimensional in vitro systems have been shown to recapitulate the drug sensitivity pattern of tumor cells in vivo. MDA-231 tumor cell spheroids exhibit higher protein levels of the cyclin-dependent kinase (Cdk) inhibitors p21 and p27 and >10-fold lower Cdk2 activity compared to adherent cell monolayers, as well as pRb hypophosphorylation, a predominant G1 population, and a cisplatin 1-h IC50 of approximately 100 μM. Treatment of MDA-231 cells in monolayer with cisplatin for 1 h, subsequently grown as spheroids, increased steady-state TGF-β1 mRNA levels, secretion of active TGF-β, cellular Cdk2 activity, pRb phosphorylation, and p21 protein levels, while downregulating p27. Accumulation of cells in G2M and progression into S were noted 48 h after treatment with 100 μM cisplatin. We tested whether drug-induced upregulation of TGF-β1 and p21, perhaps by preventing cell cycle progression, were protective mechanisms against drug-mediated toxicity by using neutralizing anti-TGF-β antibodies. Anti-TGF-β antibodies diminished the induction of p21, enhanced the activation of Cdk2, and facilitated progression into S and G2M following cisplatin treatment. This resulted in a >twofold enhancement of drug-induced DNA fragmentation and a shift in the cisplatin 1-h IC50 from 100 to <10 μM. These data suggest that tumor cell TGF-β1 may protect from DNA damage and that postchemotherapy administration of TGF-β inhibitors may facilitate progression beyond G1/S, potentially increasing the efficacy of cytotoxic chemotherapy.
AB - We have examined the effect of neutralizing TGF-β antibodies on cisplatin-mediated cytotoxicity against MDA-231 human breast tumor cell spheroids. These tridimensional in vitro systems have been shown to recapitulate the drug sensitivity pattern of tumor cells in vivo. MDA-231 tumor cell spheroids exhibit higher protein levels of the cyclin-dependent kinase (Cdk) inhibitors p21 and p27 and >10-fold lower Cdk2 activity compared to adherent cell monolayers, as well as pRb hypophosphorylation, a predominant G1 population, and a cisplatin 1-h IC50 of approximately 100 μM. Treatment of MDA-231 cells in monolayer with cisplatin for 1 h, subsequently grown as spheroids, increased steady-state TGF-β1 mRNA levels, secretion of active TGF-β, cellular Cdk2 activity, pRb phosphorylation, and p21 protein levels, while downregulating p27. Accumulation of cells in G2M and progression into S were noted 48 h after treatment with 100 μM cisplatin. We tested whether drug-induced upregulation of TGF-β1 and p21, perhaps by preventing cell cycle progression, were protective mechanisms against drug-mediated toxicity by using neutralizing anti-TGF-β antibodies. Anti-TGF-β antibodies diminished the induction of p21, enhanced the activation of Cdk2, and facilitated progression into S and G2M following cisplatin treatment. This resulted in a >twofold enhancement of drug-induced DNA fragmentation and a shift in the cisplatin 1-h IC50 from 100 to <10 μM. These data suggest that tumor cell TGF-β1 may protect from DNA damage and that postchemotherapy administration of TGF-β inhibitors may facilitate progression beyond G1/S, potentially increasing the efficacy of cytotoxic chemotherapy.
KW - Apoptosis
KW - Breast carcinoma
KW - Cell cycle
KW - Cisplatin
KW - Spheroids
KW - Transforming growth factor-β
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U2 - 10.1006/excr.1998.4261
DO - 10.1006/excr.1998.4261
M3 - Article
C2 - 9851876
AN - SCOPUS:0032534450
SN - 0014-4827
VL - 245
SP - 350
EP - 359
JO - Experimental Cell Research
JF - Experimental Cell Research
IS - 2
ER -