Abstract
BackgroundIsolated limb perfusion with TNF-α and melphalan is used with remarkable efficiency to treat unresectable limb sarcomas. Here we tested the ability of TNF-α to directly induce apoptosis of sarcoma cells. In addition, we investigated the impact of p53 in the regulation of such effect.Methodology/Principal FindingsWe first analysed the ability of TNF-α to induce apoptosis in freshly isolated tumour cells. For this purpose, sarcoma tumours (n = 8) treated ex vivo with TNF-α were processed for TUNEL staining. It revealed substantial endothelial cell apoptosis and levels of tumour cell apoptosis that varied from low to high. In order to investigate the role of p53 in TNF-α-induced cell death, human sarcoma cell lines (n = 9) with different TP53 and MDM2 status were studied for their sensitivity to TNF-α. TP53Wt cell lines were sensitive to TNF-α unless MDM2 was over-expressed. However, TP53Mut and TP53Null cell lines were resistant. TP53 suppression in TP53Wt cell lines abrogated TNF-α sensitivity and TP53 overexpression in TP53Null cell lines restored it. The use of small molecules that restore p53 activity, such as CP-31398 or Nutlin-3a, in association with TNF-α, potentiated the cell death of respectively TP53Mut and TP53Wt/MDM2Ampl. In particular, CP-31398 was able to induce p53 as well as some of its apoptotic target genes in TP53Mut cells. In TP53Wt/MDM2Ampl cells, Nutlin-3a effects were associated with a decrease of TNF-α-induced NF-κB-DNA binding and correlated with a differential regulation of pro- and anti-apoptotic genes such as TP53BP2, GADD45, TGF-β1 and FAIM.Conclusion/SignificanceMore effective therapeutic approaches are critically needed for the treatment of unresectable limb sarcomas. Our results show that restoring p53 activity in sarcoma cells correlated with increased sensitivity to TNF-α, suggesting that this strategy may be an important determinant of TNF-α-based sarcomas treatment.
Highlights
Sarcomas are rare, poorly understood cancers, refractory to standard therapies [1,2]
Further quantification of the TUNEL-positive cells revealed that TNF-a induces apoptosis of endothelial cells in most patients (69.669%) whereas for tumour cells, patients could be subdivided into three groups: patients with low apoptosis rate (10% to 17%, n = 2), patients with moderate apoptosis rate (57 to 66%, n = 3), and patients with high apoptosis rate (85% to 95%, n = 3), suggesting that sarcoma tumour cells are differentially sensitive to TNF-ainduced apoptosis (Fig. 1B)
Clinical information gained from radiological studies and pathological biopsies showed that TNF-a targeted the tumour vasculature and had no visible direct effects on tumour cells [40], direct selective cytotoxic activity against tumour cells has been described in vitro [17] with wide variation of tumour cell sensitivity
Summary
Poorly understood cancers, refractory to standard therapies [1,2] In this context, isolated limb perfusion (ILP), a highly specialized surgical technique that allows higher drug concentrations to be delivered loco-regionally, limiting treatment toxicity, can be used to treat unresectable soft tissue sarcomas (STS) of extremities avoiding limb amputation. It has been demonstrated that TNF-a increases intratumoural vessel permeability and reduces interstitial pressure, facilitating drug penetration in tumours [11] These data suggest that the potent antitumour activity of ILP with TNF-a and melphalan is due to a dual targeting effect: first, TNF-a increases the permeability of tumour vessels and melphalan reaches the tumour cells and induces cell death. We investigated the impact of p53 in the regulation of such effect
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
