Defense Date

2024

Document Type

Thesis

Degree Name

Master of Science

Department

Biology

First Advisor

Dr. Anindita Das

Abstract

Doxorubicin (DOX) is a common chemo-drug for breast cancer, but it causes severe cardiotoxicity. This study explores combining Sildenafil (Sild) and Rapamycin (Rapa), which inhibit phosphodiesterase-5 (PDE5) and mTOR, respectively, to boost DOX’s anticancer, but provide cardioprotection. Triple negative human (MDA-MB-231) and murine (4T1) breast cancer cells were treated with DOX (1 µM) with/without Rapa (100 nM) and Sild (10 µM) for 24-72 hours to analyze cell death, cell viability assays and protein expression. Human epidermal growth factor receptor 2-positive breast cancer (SKBr3) spheroids were treated with the same concentrations of DOX and/or AG825 (5µM) with/without Rapa and/or Sild for 48 hours, followed by 48 hours incubation in fresh medium. The SKBr3 medium was used to treat human cardiomyocytes (AC16) for 48 hours to evaluate cardioprotection. Sild and Rapa combination enhanced DOX-induced killing of all three-breast cancer cells, suppressed mTOR signaling and Bcl2 expression, and increased cleaved PARP in cancer cells, while reducing cardiomyocyte death compared to individual treatment. Adult female C57/B6 mice were treated with DOX (6 mg/kg/twice weekly) for 2 weeks followed by Afatinib (10 mg/kg, oral gavage, 5 days/week) for 2 weeks with/without Rapa (0.25 mg/kg/day) and Sild (1.4 mg/kg/day). After 12 weeks, the combination alleviated DOX+Afatinib-induced cardiac dysfunction with improvement of survival and body weight. This study manifests a unique combination with Sild and Rapa, enhancing chemotherapy efficacy, while safeguarding cardiac function, representing a promising advancement for breast cancer chemo-immunotherapy strategy.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

8-7-2024

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