Anticancer Activity of Ω-6 Fatty Acids through Increased 4-HNE in Breast Cancer Cells
Chhanda Bose1, Ashly Hindle1, Jihyun Lee1
1Department of Internal Medicine, Division of Hematology and Oncology, Texas Tech University Health Sciences Center, Lubbock, TX 79430, USA.
Abstract:
Her2-amplified breast cancers resistant to available Her2-targeted therapeutics continue to be a challenge in breast cancer therapy. Dox is the mainstay of chemotherapy of all types of breast cancer, but its usefulness is limited by cumulative cardiotoxicity. Because oxidative stress caused by dox generates the pro-apoptotic Ω-6 PUFA metabolite 4-hydroxynonenal (4-HNE), we surmised that Ω-6 PUFAs would increase the effectiveness of dox chemotherapy. Since the mercapturic acid pathway enzyme RALBP1 (also known as RLIP76 or Rlip) that limits cellular accumulation of 4-HNE also mediates dox resistance, the combination of Ω-6 PUFAs and Rlip depletion could synergistically improve the efficacy of dox. Thus, we studied the effects of the Ω-6 PUFA arachidonic acid (AA) and Rlip knockdown on the antineoplastic activity of dox towards Her2-amplified breast cancer cell lines SK-BR-3, which is sensitive to Her2 inhibitors, and AU565, which is resistant. AA increased lipid peroxidation, 4-HNE generation, apoptosis, cellular dox concentration and dox cytotoxicity in both cell lines while sparing cultured immortalized cardiomyocyte cells. The known functions of Rlip including clathrin-dependent endocytosis and dox efflux were inhibited by AA. Our results support a model in which 4-HNE generated by AA overwhelms the capacity of Rlip to defend against apoptosis caused by dox or 4-HNE. We propose that Ω-6 PUFA supplementation could improve the efficacy of dox or Rlip inhibitors for treating Her2-amplified breast cancer.
Insights
Omega-6 polyunsaturated fatty acids (PUFAs) enhance doxorubicin (Dox) chemotherapy effectiveness against Her2-amplified breast cancer by increasing apoptosis. Supplementing with omega-6 PUFAs may improve Dox or Rlip inhibitor efficacy.
Area of Science:
- Oncology
- Molecular Biology
- Biochemistry
Background:
- Her2-amplified breast cancers present therapeutic challenges due to resistance to targeted therapies.
- Doxorubicin (Dox) is a primary chemotherapy agent, but its use is limited by cardiotoxicity.
- Oxidative stress from Dox generates 4-hydroxynonenal (4-HNE), a pro-apoptotic metabolite.
Purpose of the Study:
- To investigate if omega-6 polyunsaturated fatty acids (PUFAs) enhance Dox chemotherapy efficacy in Her2-amplified breast cancer.
- To determine the combined effect of omega-6 PUFAs and Rlip depletion on Dox activity.
- To explore the underlying mechanisms of enhanced Dox cytotoxicity.
Main Methods:
- Utilized Her2-amplified breast cancer cell lines (SK-BR-3 and AU565).
- Administered arachidonic acid (AA), an omega-6 PUFA, and performed Rlip knockdown.
- Assessed lipid peroxidation, 4-HNE generation, apoptosis, cellular Dox concentration, and cytotoxicity.
- Evaluated effects on cardiomyocyte cells and Rlip functions (endocytosis, Dox efflux).
Main Results:
- AA increased lipid peroxidation, 4-HNE generation, apoptosis, and Dox cytotoxicity in both cell lines.
- AA treatment spared cultured immortalized cardiomyocyte cells from Dox-induced damage.
- AA inhibited Rlip-mediated functions, including clathrin-dependent endocytosis and Dox efflux.
- A model was proposed where AA-generated 4-HNE overwhelms Rlip's protective capacity.
Conclusions:
- Omega-6 PUFA supplementation, specifically arachidonic acid, can enhance the efficacy of doxorubicin chemotherapy in Her2-amplified breast cancer.
- The combination of omega-6 PUFAs and Rlip inhibition shows synergistic potential for improving anti-cancer activity.
- This approach may offer a strategy to overcome Dox resistance and mitigate cardiotoxicity.
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