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Induction of Breast Cancer Cell Apoptosis by TRAIL and Smac Mimetics: Involvement of RIP1 and cFLIP

Christian Holmgren1, Ellen Sunström Thörnberg1, Victoria Granqvist1

  • 1Translational Cancer Research, Lund University, Medicon Village, Building 404:C3, SE-22363 Lund, Sweden.

Current Issues in Molecular Biology
|October 26, 2022
PubMed

Insights

Smac mimetics like LCL-161 combined with TRAIL induce apoptosis in breast cancer cells by enabling RIPK1-caspase-8 complex formation, bypassing c-FLIP inhibition. This combination offers a promising therapeutic strategy.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Death Research

Background:

  • Smac mimetics and TRAIL are investigated for cancer therapy.
  • The precise molecular mechanisms of their combination treatment are not fully understood.
  • Understanding these mechanisms is crucial for optimizing breast cancer treatment.

Purpose of the Study:

  • To elucidate the molecular mechanisms underlying the combination of Smac mimetic LCL-161 and TRAIL in breast cancer cells.
  • To investigate the roles of caspase-8, RIPK1, and c-FLIP in mediating apoptosis.
  • To identify factors determining differential responses to combination therapy.

Main Methods:

  • Utilized three breast cancer cell lines: MDA-MB-468, CAMA-1, and MCF-7.
  • Performed cell death assays and Western blot analysis.
  • Investigated the effects of LCL-161, TRAIL, and genetic manipulations (downregulation of caspase-8, RIPK1, c-FLIP).

Main Results:

  • Combination treatment induced apoptosis and caspase-8 cleavage in MDA-MB-468 and CAMA-1 cells, but not MCF-7.
  • RIPK1 downregulation, not kinase inhibition, suppressed apoptosis in CAMA-1 cells.
  • RIPK1 association with caspase-8 preceded apoptosis, and c-FLIP downregulation enhanced TRAIL/LCL-161 effects in MCF-7 cells.

Conclusions:

  • LCL-161 facilitates the formation of a RIPK1-caspase-8 complex, promoting apoptosis.
  • This complex formation circumvents c-FLIP-mediated inhibition of caspase activation.
  • The findings support a model for Smac mimetic and TRAIL combination therapy in specific breast cancer contexts.
Keywords:
RIP1Smac mimeticTRAILapoptosisbreast cancerc-FLIP

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