Astragalus Extract Helps Combat Melanoma and Boosts Immune Response

Jenn Hoskins
22nd August, 2024

Astragalus Extract Helps Combat Melanoma and Boosts Immune Response

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Shanghai University of Traditional Chinese Medicine found that Astragalus polysaccharide (APS) can inhibit melanoma stem cells (MSCs)
  • APS reduced the ability of MSCs to form tumors and decreased the expression of key cancer stem cell markers like CD133, BMI1, and CD47
  • APS also down-regulated PD-L1 expression, enhancing the immune response by increasing CD4+ and CD8+ T cell infiltration in tumor tissues
Melanoma is a highly aggressive form of skin cancer, often driven by cancer stem cells (CSCs) and mechanisms of tumor immune evasion. Despite advances in treatment, effective therapies remain elusive. A recent study conducted by researchers at Shanghai University of Traditional Chinese Medicine has explored the potential of Astragalus polysaccharide (APS), a principal active component derived from Astragalus membranaceus, in treating melanoma[1]. The study focused on how APS affects melanoma stem cells (MSCs), which are a subset of CSCs specifically associated with melanoma. MSCs are known for their ability to self-renew and differentiate into various cell types, contributing to tumor growth, metastasis, and resistance to conventional therapies[2]. The researchers aimed to understand whether APS could inhibit the self-renewal ability of MSCs and reduce the expression of key CSC markers. To assess this, the researchers conducted a series of in vitro and in vivo experiments. They measured tumor sphere formation, a proxy for self-renewal ability, and tumorigenicity, which assesses the ability to form tumors in living organisms. They also used RT-qPCR and western blot techniques to evaluate the expression of MSC markers such as CD133, BMI1, and CD47. Flow cytometry was employed to analyze the activation of the immune system in melanoma-bearing mice treated with APS. The results were promising. APS significantly attenuated the tumor sphere formation of MSCs in vitro and reduced their tumorigenicity in vivo. It also decreased the expression of CD133, BMI1, and CD47, which are markers associated with CSCs and tumor progression[3][4]. CD133, in particular, has been linked to shorter survival and tumor recurrence in various cancers[3]. CD47 is known to act as a "don't eat me" signal that protects tumor cells from being phagocytosed by the immune system[4]. One of the critical findings of the study was the role of PD-L1, a protein that helps tumors evade the immune system by inhibiting T-cell activity. The researchers used B16 melanoma cells with overexpressed and knocked-down PD-L1 to confirm that APS inhibited MSC induction by down-regulating PD-L1 expression. This down-regulation led to increased infiltration of CD4+ and CD8+ T cells in tumor tissues, enhancing the body's immune response against the tumor[5]. The study ties together previous findings on the role of immune evasion and CSCs in melanoma. For instance, melanomas have been pivotal in developing cancer immunotherapy, including the use of antibodies against PD-1 and CTLA-4 to boost immune responses[5]. However, the presence of CSCs and mechanisms like PD-L1-mediated immune evasion have limited the effectiveness of these therapies. By targeting both MSCs and PD-L1, APS offers a dual approach to overcoming these challenges. In conclusion, the study provides compelling evidence that APS could be a prospective therapeutic agent for treating melanoma by inhibiting MSC induction and overcoming tumor immune evasion through reducing PD-L1 expression. This dual mechanism could potentially offer a more effective treatment strategy for melanoma, addressing both the root cause of tumor progression and the barriers to effective immune response.

MedicineHealthBiochem

References

Main Study

1) Modulation of PD-L1 by Astragalus polysaccharide attenuates the induction of melanoma stem cell properties and overcomes immune evasion.

Published 21st August, 2024

Journal: BMC cancer

Issue: Vol 24, Issue 1, Aug 2024

Related Studies

2) Effect of melanoma stem cells on melanoma metastasis.

https://doi.org/10.3892/ol.2021.12827

3) New emerging roles of CD133 in cancer stem cell: Signaling pathway and miRNA regulation.

https://doi.org/10.1002/jcp.28824

4) The CD47-signal regulatory protein alpha (SIRPa) interaction is a therapeutic target for human solid tumors.

https://doi.org/10.1073/pnas.1121623109

5) A Commotion in the Skin: Developing Melanoma Immunotherapies.

https://doi.org/10.1016/j.jid.2022.01.025


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