Mcl-1 regulates reactive oxygen species via NOX4 during chemotherapy-induced senescence
Abeba Demelash1, Lukas W Pfannenstiel1, Li Liu1
1Department of Immunology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
Abstract:
Mcl-1, a Bcl-2 family member, is highly expressed in a variety of human cancers and is believed to enhance tumorigenic potential and chemotherapy resistance through the inhibition of apoptosis and senescence. We previously reported that Mcl-1's regulation of chemotherapy-induced senescence (CIS) is dependent on its ability to prevent reactive oxygen species (ROS) generation. In this report, we demonstrate that Mcl-1-regulated CIS requires not only ROS, but specifically mitochondrial ROS, and that these events are upstream of activation of the DNA damage response, another necessary step toward senescence. Mcl-1's anti-senescence activity also involves the unique ability to inhibit ROS formation by preventing the upregulation of pro-oxidants. Specifically, we found that NADPH oxidases (NOXs) are regulated by Mcl-1 and that NOX4 expression in particular is a required step for CIS induction that is blocked by Mcl-1. Lastly, we illustrate that by preventing expression of NOX4, Mcl-1 limits its availability in the mitochondria, thereby lowering the production of mitochondrial ROS during CIS. Our studies not only define the essential role of Mcl-1 in chemoresistance, but also for the first time link a key pro-survival Bcl-2 family member with the NOX protein family, both of which have significant ramifications in cancer progression.
Insights
Mcl-1 protein prevents chemotherapy-induced senescence (CIS) by inhibiting mitochondrial reactive oxygen species (ROS) generation, specifically by blocking the expression of NADPH oxidase 4 (NOX4). This reveals a new link between Mcl-1 and NOX proteins in cancer progression.
Area of Science:
- Molecular Biology
- Cancer Biology
- Cellular Senescence
Background:
- Mcl-1, a Bcl-2 family member, is upregulated in many cancers, contributing to tumor growth and resistance to chemotherapy.
- Mcl-1's role in regulating chemotherapy-induced senescence (CIS) is linked to its control over reactive oxygen species (ROS) generation.
Purpose of the Study:
- To elucidate the specific mechanisms by which Mcl-1 regulates CIS, focusing on the role of mitochondrial ROS and NADPH oxidases (NOXs).
- To investigate the upstream events in Mcl-1-regulated CIS, including the DNA damage response and pro-oxidant regulation.
Main Methods:
- Investigated the requirement of mitochondrial ROS in Mcl-1-regulated CIS.
- Examined the role of NADPH oxidases (NOXs), particularly NOX4, in Mcl-1's anti-senescence activity.
- Assessed the impact of Mcl-1 on pro-oxidant expression and ROS production during CIS.
Main Results:
- Mcl-1-regulated CIS requires mitochondrial ROS, which are upstream of the DNA damage response.
- Mcl-1 inhibits CIS by preventing the upregulation of pro-oxidants, specifically by blocking NOX4 expression.
- Mcl-1 limits NOX4 availability in mitochondria, thereby reducing mitochondrial ROS production during CIS.
Conclusions:
- Mcl-1 plays a critical role in chemoresistance by inhibiting mitochondrial ROS production through the regulation of NOX4.
- This study establishes a novel connection between the pro-survival Bcl-2 family member Mcl-1 and the NOX protein family in cancer progression.
More Related Videos
Related Concept Videos
01:46Electron Transport Chain: Complex I and II
ROS generation is regulated and maintained at moderate levels necessary...
01:31The Intrinsic Apoptotic Pathway
02:53Adaptive Mechanisms in Cancer Cells
Some of the advantages that cancer cells have on normal cells include - enhanced ability to divide without terminally differentiating, induce new blood vessel formation,...
02:23Abnormal Proliferation
01:43Electron Transport Chain: Complex III and IV
01:37Mitochondria