Anti-EGFR antibody efficiently and specifically inhibits human TSC2-/- smooth muscle cell proliferation. Possible treatment options for TSC and LAM

PLoS One. 2008;3(10):e3558. doi: 10.1371/journal.pone.0003558. Epub 2008 Oct 29.


Background: Tuberous sclerosis complex (TSC), a tumor syndrome caused by mutations in TSC1 or TSC2 genes, is characterized by the development of hamartomas. We previously isolated, from an angiomyolipoma of a TSC2 patient, a homogenous population of smooth muscle-like cells (TSC2(-/-) ASM cells) that have a mutation in the TSC2 gene as well as TSC2 loss of heterozygosity (LOH) and consequently, do not produce the TSC2 gene product, tuberin. TSC2(-/-) ASM cell proliferation is EGF-dependent.

Methods and findings: Effects of EGF on proliferation of TSC2(-/-) ASM cells and TSC2(-/-) ASM cells transfected with TSC2 gene were determined. In contrast to TSC2(-/-) ASM cells, growth of TSC2-transfected cells was not dependent on EGF. Moreover, phosphorylation of Akt, PTEN, Erk and S6 was significantly decreased. EGF is a proliferative factor of TSC2(-/-) ASM cells. Exposure of TSC2(-/-) ASM cells to anti-EGFR antibodies significantly inhibited their proliferation, reverted reactivity to HMB45 antibody, a marker of TSC2(-/-) cell phenotype, and inhibited constitutive phosphorylation of S6 and ERK. Exposure of TSC2(-/-) ASM cells to rapamycin reduced the proliferation rate, but only when added at plating time. Although rapamycin efficiently inhibited S6 phosphorylation, it was less efficient than anti-EGFR antibody in reverting HMB45 reactivity and blocking ERK phosphorylation. In TSC2(-/-) ASM cells specific PI3K inhibitors (e.g. LY294002, wortmannin) and Akt1 siRNA had little effect on S6 and ERK phosphorylation. Following TSC2-gene transfection, Akt inhibitor sensitivity was observed.

Conclusion: Our results show that an EGF independent pathway is more important than that involving IGF-I for growth and survival of TSC(-/-) ASM cells, and such EGF-dependency is the result of the lack of tuberin.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Antibodies / pharmacology*
  • Antibodies / therapeutic use
  • Antibody Affinity
  • Antibody Specificity
  • Cell Proliferation / drug effects*
  • Cells, Cultured
  • ErbB Receptors / immunology*
  • Female
  • Humans
  • Lymphangioleiomyomatosis / genetics
  • Lymphangioleiomyomatosis / metabolism
  • Lymphangioleiomyomatosis / pathology
  • Lymphangioleiomyomatosis / therapy*
  • Models, Biological
  • Muscle, Smooth, Vascular / drug effects
  • Muscle, Smooth, Vascular / metabolism
  • Muscle, Smooth, Vascular / pathology
  • Myocytes, Smooth Muscle / drug effects*
  • Myocytes, Smooth Muscle / metabolism
  • Myocytes, Smooth Muscle / physiology
  • Smooth Muscle Tumor / genetics
  • Smooth Muscle Tumor / metabolism
  • Smooth Muscle Tumor / pathology
  • Smooth Muscle Tumor / therapy*
  • Transfection
  • Tuberous Sclerosis / genetics
  • Tuberous Sclerosis / metabolism
  • Tuberous Sclerosis / pathology
  • Tuberous Sclerosis / therapy*
  • Tuberous Sclerosis Complex 2 Protein
  • Tumor Suppressor Proteins / genetics*
  • Tumor Suppressor Proteins / metabolism


  • Antibodies
  • TSC2 protein, human
  • Tuberous Sclerosis Complex 2 Protein
  • Tumor Suppressor Proteins
  • EGFR protein, human
  • ErbB Receptors