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ROS-Responsive Micelles Loaded with Podophyllotoxin Inhibit Tumor Growth via ROS Self-Amplification and Regulation of
Shuaiheng Song1, Qiang Shao1, Siyi Liang1
1Department of Organic Chemistry, College of Pharmacy, Harbin Medical University, Harbin 150081, China.
Abstract:
Podophyllotoxin (PPT) inhibits tumors such as lung cancer and breast cancer. However, it has poor water solubility and causes gastrointestinal dysfunction and bone marrow suppression, which severely limit its clinical application. Based on the differential reactive oxygen species (ROS) levels between tumor microenvironments and normal tissues, we designed and constructed a ROS-responsive micelle delivery system, successfully fabricating blank micelles (M) and PPT-loaded micelles (M@PPT). Both micelles exhibited good particle size uniformity, colloidal stability, and biosafety. The ROS responsiveness experiment revealed that, after incubating blank micelles (M) with 10 mM H2O2, the particle size increased significantly, and the size distribution broadened. High-performance liquid chromatography (HPLC) confirmed the release of cinnamaldehyde from the micelles upon H2O2 exposure. Additionally, DCFH-DA assays demonstrated that treatment with blank micelles (M) enhanced intracellular ROS levels. In vitro release studies showed that drug-loaded micelles (M@PPT) achieved 77.76% cumulative PPT release within 24 h in a buffer containing 10 mM H2O2, significantly exceeding the release observed in the H2O2-free control group. These results collectively validate the ROS-responsive disintegration of micelles and the subsequent release of cinnamaldehyde. The liberated cinnamaldehyde further amplified intracellular ROS levels, establishing a positive feedback loop that accelerated drug release. Cellular assays revealed superior tumor growth inhibition by M@PPT over free PPT, mediated through apoptosis induction, G2/M phase cell cycle arrest, downregulation of the anti-apoptotic protein Survivin, and upregulation of the p21 protein. In vivo studies further confirmed the enhanced antitumor efficacy and improved biosafety of M@PPT compared to free PPT. This ROS-responsive micellar system, by enabling tumor-targeted drug delivery and controlled release, provides a novel strategy to optimize the clinical utility of podophyllotoxin-based chemotherapeutics.
Insights
This study developed a novel micelle system that releases podophyllotoxin (PPT) in response to reactive oxygen species (ROS) found in tumors. This targeted delivery enhances anticancer efficacy and reduces side effects for lung and breast cancer treatment.
Area of Science:
- Biomedical Engineering
- Materials Science
- Oncology
Background:
- Podophyllotoxin (PPT) exhibits anticancer properties against lung and breast cancers but suffers from poor solubility and severe side effects, limiting its clinical use.
- Tumor microenvironments have higher reactive oxygen species (ROS) levels than normal tissues, presenting an opportunity for targeted drug delivery.
- Developing stimuli-responsive drug delivery systems is crucial for improving chemotherapeutic efficacy and patient safety.
Purpose of the Study:
- To design and fabricate a ROS-responsive micelle delivery system for podophyllotoxin (PPT).
- To evaluate the PPT release kinetics, drug loading, and stability of the developed micelles.
- To assess the in vitro and in vivo antitumor efficacy and biosafety of the ROS-responsive PPT-loaded micelles (M@PPT).
Main Methods:
- Fabrication of blank (M) and PPT-loaded (M@PPT) micelles.
- Characterization of micelle particle size, uniformity, colloidal stability, and biosafety.
- Assessment of ROS-responsive drug release using HPLC and DCFH-DA assays.
- In vitro cellular assays evaluating apoptosis, cell cycle arrest, and protein expression.
- In vivo studies to confirm antitumor efficacy and biosafety.
Main Results:
- Micelles (M and M@PPT) demonstrated good particle size uniformity, stability, and biosafety.
- Blank micelles showed ROS-responsive swelling and drug release upon H2O2 exposure, confirming the system's responsiveness.
- M@PPT achieved significant PPT release in the presence of ROS, creating a positive feedback loop that enhanced drug release.
- M@PPT exhibited superior in vitro tumor growth inhibition compared to free PPT via apoptosis induction and cell cycle arrest.
- In vivo studies confirmed enhanced antitumor efficacy and improved biosafety of M@PPT over free PPT.
Conclusions:
- The developed ROS-responsive micellar system effectively delivers PPT in a targeted manner.
- This system enhances PPT's antitumor activity by leveraging the tumor microenvironment's ROS levels.
- The ROS-responsive micelles offer a promising strategy to overcome PPT's limitations and improve its clinical application in cancer therapy.
