Blockade of tumor cell transforming growth factor-betas enhances cell cycle progression and sensitizes human breast carcinoma cells to cytotoxic chemotherapy

Exp Cell Res. 1998 Dec 15;245(2):350-9. doi: 10.1006/excr.1998.4261.

Abstract

We have examined the effect of neutralizing TGF-beta 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 microM. Treatment of MDA-231 cells in monolayer with cisplatin for 1 h, subsequently grown as spheroids, increased steady-state TGF-beta1 mRNA levels, secretion of active TGF-beta, 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 microM cisplatin. We tested whether drug-induced upregulation of TGF-beta1 and p21, perhaps by preventing cell cycle progression, were protective mechanisms against drug-mediated toxicity by using neutralizing anti-TGF-beta antibodies. Anti-TGF-beta 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 microM. These data suggest that tumor cell TGF-beta1 may protect from DNA damage and that postchemotherapy administration of TGF-beta inhibitors may facilitate progression beyond G1/S, potentially increasing the efficacy of cytotoxic chemotherapy.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Antineoplastic Agents / pharmacology*
  • Antineoplastic Agents / therapeutic use
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / pathology
  • Breast Neoplasms / physiopathology
  • CDC2-CDC28 Kinases*
  • Cell Aggregation / drug effects
  • Cell Cycle / drug effects*
  • Cell Cycle Proteins*
  • Cell Death / drug effects
  • Cisplatin / pharmacology*
  • Cisplatin / therapeutic use
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclin-Dependent Kinase Inhibitor p27
  • Cyclin-Dependent Kinases / antagonists & inhibitors
  • Cyclin-Dependent Kinases / metabolism
  • Cyclins / metabolism
  • DNA Fragmentation / drug effects
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Immunoglobulin G / pharmacology
  • Inhibitory Concentration 50
  • Microtubule-Associated Proteins / metabolism
  • Phosphorylation / drug effects
  • Protein-Serine-Threonine Kinases / antagonists & inhibitors
  • Protein-Serine-Threonine Kinases / metabolism
  • Proteins
  • Retinoblastoma Protein / metabolism
  • Transforming Growth Factor beta / antagonists & inhibitors*
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / immunology
  • Transforming Growth Factor beta / metabolism
  • Tumor Cells, Cultured
  • Tumor Suppressor Proteins*

Substances

  • Antineoplastic Agents
  • CDKN1A protein, human
  • Cell Cycle Proteins
  • Cyclin-Dependent Kinase Inhibitor p21
  • Cyclins
  • Immunoglobulin G
  • Microtubule-Associated Proteins
  • Proteins
  • Retinoblastoma Protein
  • Transforming Growth Factor beta
  • Tumor Suppressor Proteins
  • Cyclin-Dependent Kinase Inhibitor p27
  • Protein-Serine-Threonine Kinases
  • CDC2-CDC28 Kinases
  • CDK2 protein, human
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinases
  • Cisplatin