Editor: Tiffany
A newly designed supramolecular peptide, sBBI&PDP, effectively targets both β-catenin and PD-L1, enhancing immunotherapy outcomes for patients with hepatocellular carcinoma (HCC).
Key Highlights
- Research Question:
Can a supramolecular peptide targeting β-catenin and PD-L1 improve the efficacy of immunotherapy in hepatocellular carcinoma? - Research Difficulties:
The challenge of simultaneously targeting the Wnt/β-catenin signaling pathway and immune checkpoint inhibitors in HCC. - Key Findings:
The novel sBBI&PDP nanoparticle significantly inhibited HCC growth, enhanced CD8+ T cell activity, and demonstrated superior antitumor efficacy compared to existing therapies. - Innovative Aspects:
The combination of an L-enantiomeric peptide that inhibits β-catenin and a D-enantiomeric peptide that blocks PD-L1 in a single supramolecular structure. - Importance of the Study:
This research offers a promising new strategy for improving the low response rate of HCC patients to current immune checkpoint therapies.
Context of Hepatocellular Carcinoma Treatment
Hepatocellular carcinoma (HCC) is a primary malignancy of the liver and represents a significant global health crisis, with projections indicating that by 2030, one million people may succumb to liver cancer. Advanced HCC patients face grim prognoses, as existing treatment options, particularly immune checkpoint inhibitors (ICIs) targeting PD-1 and PD-L1, exhibit limited efficacy, benefiting only about 20% of those treated. This inadequate response is closely associated with the activation of the Wnt/β-catenin signaling pathway in HCC, which facilitates tumor immune evasion and resistance to therapies. The Wnt/β-catenin pathway plays a multifaceted role in promoting tumor growth by fostering an immunosuppressive microenvironment, characterized by increased regulatory T cell activity and diminished infiltration of CD8+ T cells. Consequently, there is a pressing need for innovative therapeutic strategies that can effectively target both the Wnt/β-catenin signaling pathway and PD-L1 to enhance the efficacy of immunotherapy in HCC patients.
Objectives of Targeting Wnt/β-Catenin and PD-L1
The research aimed to develop a novel supramolecular peptide that could simultaneously inhibit the Wnt/β-catenin signaling pathway and block PD-L1 activity, thereby optimizing immunotherapy for HCC. The primary objectives of the study included: (1) the synthesis and characterization of a racemic spherical supramolecular peptide, termed sBBI&PDP, that combines two distinct peptide functionalities; (2) the evaluation of the antiproliferative effects of the sBBI&PDP nanoparticle in vitro and in vivo, particularly its ability to inhibit HCC growth and enhance the immune response; (3) the investigation of the mechanism of action by which sBBI&PDP modulates the immune landscape of HCC, focusing on its effects on CD8+ T cell infiltration and activity; and (4) the assessment of the safety and biosafety profile of the developed nanoparticle to ensure its potential for clinical translation. Ultimately, the study sought to provide a promising new therapeutic approach for improving the low response rates of HCC patients to current immune checkpoint therapies.
Figure 1. Schematic depiction of sBBI&PDP synthesis and function for tumor-cytotoxic effect and inhibited growth of hepatocellular carcinoma.
Experimental Approach and Key Findings
(1) Experimental Process Outline:
- Design and synthesis of the supramolecular peptide, sBBI&PDP.
- Characterization of the physical properties of sBBI&PDP using techniques such as FT-IR, UV-vis, and Zeta potential analysis.
- Assessment of cellular uptake of sBBI&PDP in HCC cell lines and macrophages.
- Evaluation of the release kinetics of peptides from sBBI&PDP in the presence of glutathione (GSH).
- In vitro studies to analyze the effects of sBBI&PDP on HCC cell proliferation, apoptosis, and cell cycle progression.
- Development of orthotopic and patient-derived xenograft (PDX) mouse models of HCC.
- In vivo evaluation of the antitumor efficacy of sBBI&PDP in mouse models.
- Analysis of immune cell infiltration and expression levels of key proteins in tumor tissues post-treatment.
- Safety and biocompatibility assessments of sBBI&PDP in healthy mice.
(2) Key Experiments
- Cellular Uptake Evaluation
Procedure: The uptake of sBBI&PDP in HCC cell line Hepa1-6 and macrophage cell line RAW264.7 was quantified using confocal microscopy. Peptides were labeled with fluorescein isothiocyanate (FITC) for visualization.
Result: The sBBI&PDP nanoparticles exhibited significantly enhanced cellular uptake in Hepa1-6 cells compared to the individual peptides (BBI and PDP), while showing reduced uptake in RAW264.7 macrophages due to increased electrostatic repulsion.
Finding: The results indicated that sBBI&PDP could effectively target HCC cells while minimizing macrophage phagocytosis, supporting its potential for selective tumor targeting.
Figure 2. Uptake images and quantitative analysis of sBBI&PDP observed by confocal laser scanning microscope in the Hepa1-6 hepatoma cells or RAW264.7 macrophagocytes compared with sBBI, BBI, PDP or Control.
- Antitumor Efficacy in Mouse Models
Procedure: Orthotopic homograft mouse models of HCC were established using Hepa1-6 cells. Mice were treated with sBBI&PDP, sBBI, anti-PD-L1, or control solutions via tail vein injections every two days.
Result: Tumor growth was significantly inhibited in the sBBI&PDP group, with fewer tumor nodules and reduced tumor size observed compared to control and other treatment groups.
Finding: The sBBI&PDP nanoparticle demonstrated superior antitumor efficacy, suggesting its potential as a potent therapeutic agent for HCC. - Mechanistic Analysis of Immune Response
Procedure: Proteomic analysis and immunohistochemical staining of tumor tissues were performed to assess the expression levels of β-catenin and PD-L1. Gene set enrichment analysis (GSEA) was utilized to evaluate changes in immune response pathways.
Result: The sBBI&PDP treatment led to significantly reduced levels of β-catenin and PD-L1, alongside an increased infiltration of CD8+ T cells and decreased regulatory T cells in tumor tissues.
Finding: This experiment confirmed that sBBI&PDP enhances the immune response against HCC by modulating key signaling pathways and promoting cytotoxic T cell activity.
Figure 3. The immunohistochemical staining results for β-catenin in hepatoma tissue.
Implications for Future Cancer Immunotherapy
This study presents a groundbreaking approach to enhancing immunotherapy for hepatocellular carcinoma (HCC) through the development of a novel supramolecular peptide, sBBI&PDP, which simultaneously targets the Wnt/β-catenin signaling pathway and PD-L1. The innovative design of the sBBI&PDP nanoparticle, which combines an L-enantiomeric peptide that inhibits β-catenin with a D-enantiomeric peptide that blocks PD-L1, represents a significant advancement in the treatment of HCC. The study found that sBBI&PDP effectively inhibited tumor growth, enhanced CD8+ T cell infiltration, and exhibited superior antitumor efficacy compared to existing therapies in both in vitro and in vivo models.
Moreover, the research demonstrated that the use of sBBI&PDP revitalizes immune checkpoint blockade strategies, offering a promising new avenue for improving the response rates of HCC patients to immunotherapy. In conclusion, the study underscores the importance of targeting multiple pathways involved in tumor immune evasion and highlights the potential of supramolecular peptides as a versatile and effective strategy for cancer immunotherapy. The findings contribute to the growing body of evidence supporting the development of personalized, PPI-targeted therapies, which could significantly enhance treatment outcomes for cancer patients.
Reference:
Zhou, Zhengjun, et al. “Targeting β-catenin and PD-L1 simultaneously by a racemic supramolecular peptide for the potent immunotherapy of hepatocellular carcinoma.” Theranostics 13.10 (2023): 3371.