Smac mimetic‑induced caspase‑independent necroptosis requires RIP1 in breast cancer
Gongsheng Jin1, Yadong Lan2, Fusheng Han2
1Department of Breast Surgery, The First Affiliated Hospital of Anhui Medical University, Hefei, Anhui 230022, P.R. China.
Abstract:
There is an urgent requirement for the development of novel targeted therapies to treat breast cancer, which is the most comment type of malignancy among women. The evasion of apoptosis is a hallmark of cancer, and is often due to the upregulation of inhibitor of apoptosis proteins (IAPs) in tumor cells. Second mitochondrial‑derived activator of caspase/direct IAP‑binding protein with low PI is a natural IAP antagonist, which is found in the mitochondrion; this protein has a motif, which binds to a surface groove on the baculovirus IAP repeat domains of the IAPs. In the present study, the effects of the LCL161 Smac mimetic, a small molecule IAP antagonist, on breast cell lines was examined. The results from MTT and colony formation assays demonstrated that LCL161 markedly inhibited the proliferation and induced the apoptosis of MDA‑MB‑231 and MCF‑7 cell lines. As determined by western blotting, cIAP1 was degraded in the breast cancer cells, which occurred in an LCL161‑dependent manner. Upon caspase activation, LCL161 treatment induced necroptosis, another form of programmed cell death. The downregulation of receptor‑interacting protein kinase‑1 via small interfering RNA protected the cells from LCL161‑induced necroptosis. Taken together, the results of the present study showed that LCL161 can induce multiple forms of programmed cell death in breast cancer cells, and may thus offer promise as an anticancer agent in diverse genotypic backgrounds.
Insights
The Smac mimetic LCL161 effectively inhibits breast cancer cell proliferation and induces apoptosis. This novel targeted therapy also triggers necroptosis, offering promise for diverse breast cancer genotypes.
Area of Science:
- Oncology
- Molecular Biology
- Pharmacology
Background:
- Breast cancer is a leading cause of cancer death in women, necessitating novel targeted therapies.
- Cancer cells evade apoptosis through upregulated inhibitor of apoptosis proteins (IAPs).
- Second mitochondrial-derived activator of caspase (Smac) is a natural IAP antagonist.
Purpose of the Study:
- To investigate the effects of the Smac mimetic LCL161 on breast cancer cell lines.
- To determine LCL161's potential as a targeted anticancer agent.
Main Methods:
- MTT and colony formation assays were used to assess cell proliferation and apoptosis.
- Western blotting was employed to analyze protein degradation (cIAP1).
- Small interfering RNA (siRNA) was used to downregulate receptor-interacting protein kinase-1 (RIPK1).
Main Results:
- LCL161 significantly inhibited proliferation and induced apoptosis in MDA-MB-231 and MCF-7 breast cancer cells.
- LCL161 treatment led to the degradation of cIAP1 in a dose-dependent manner.
- LCL161 induced necroptosis, which was dependent on caspase activation and RIPK1.
Conclusions:
- LCL161 acts as a potent inducer of multiple programmed cell death pathways in breast cancer cells.
- LCL161 demonstrates potential as a promising anticancer agent for breast cancer treatment.
- Targeting IAPs with Smac mimetics like LCL161 represents a viable therapeutic strategy.
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