Nanoliposomes modulated tumoral exosomes augments cancer immunotherapy

Cancer is a complex disease characterized by the interplay between cancer cells and their surrounding microenvironment. One key player in this intricate network is the fibroblast, a type of cell that is typically involved in tissue repair and maintenance. However, in the context of cancer, fibroblasts can be hijacked by cancer cells and transformed into cancer-associated fibroblasts (CAFs), which play a crucial role in tumor growth and progression.

Understanding the Role of Exosomes

Recent research has shed light on the role of exosomes, tiny vesicles released by cancer cells, in the transformation of fibroblasts into CAFs. This process occurs in two steps: first, cancer cells release exosomes that program quiescent fibroblasts into activated CAFs, and second, cancer cells maintain the CAF phenotype through the activation of specific signaling pathways.

Targeting the Two-Step Process

In light of this knowledge, researchers at Harvard Medical School have explored the potential of inhibiting this two-step process to normalize CAFs and enhance the efficacy of immunotherapy. One approach involves targeting cancer cell-derived exosomes using nanoliposomes, which are lipid-based nanoparticles designed to inhibit exosome biogenesis and release. By blocking this initial step, the differentiation of lung fibroblasts into CAFs can be prevented.

Additionally, another strategy focuses on targeting the fibroblast growth factor receptor (FGFR)–Wnt/β-catenin signaling pathway, which is involved in maintaining the CAF phenotype. Using CAF-targeted nanoliposomes, researchers can block two distinct nodes in this pathway, effectively reversing the activation of CAFs into quiescent fibroblasts.

Mechanistically inspired nanoliposomes remodel CAFs

(A) Tumor-targeted nanoliposomes enter lung cancer cells via binding to EpCAM and release their cargo to inhibit exosome biogenesis and release. In parallel, GPR77/CD10-targeted nanoliposomes allow selective targeting of CAFs, where the incorporated drugs reverse activated CAFs into quiescence. The combined nanoliposome-mediated normalization of CAFs blocks their immunosuppressive activity and augment αPD-L1 immunotherapy. (B) Immunofluorescence images show MRC5 human lung fibroblasts cultured for 48 hours without exosomes (left) and its activation into CAFs when cocultured with A549 cancer cell–derived PKH67-labeled exosomes for 48 hours (right) followed by staining with anti-αSMA antibody. Scale bars, 50 μm. (C) GW and SHK inhibit two consecutive steps in biogenesis and release of exosomes from a cancer cell. GW inhibits neutral sphingomyelinase enzyme (nSMase) to prevent inward budding of ceramide into intraluminal vesicles, while SHK blocks PKM2-mediated phosphorylation of SNAP23 to prevent SNARE complex formation and exocytosis, respectively. (D) Graphs show the effect of nanoliposomes on release of cancer-derived exosomes, quantified using BCA standard protein assay, CD63 ExoELISA, and EXOCET assay. A549 cancer cells were treated with nanoliposomes containing different exosome biogenesis inhibitors for 24 hours. Data shown are means ± SE [n = 3 to 4, ****P < 0.0001, analysis of variance (ANOVA) followed by Bonferroni’s post hoc test]. (E) A549 cancer cells were treated with nanoliposomes, and the released exosomes were cultured with MRC5 fibroblasts for 48 hours. (F) Flow cytometric analysis shows the effect of nanoliposomes on αSMA expression in MRC5 fibroblasts cultured with exosomes isolated from treated cancer cells. (G) Graph shows the quantified αSMA expression in MRC5 fibroblasts. Data shown are means ± SE (n = 2, ***P < 0.001, ANOVA with Bonferroni’s post hoc test). (H) Immunofluorescence imaging for αSMA in MRC5 fibroblasts cultured with nanoliposome-treated A549 cancer cell–derived exosomes for 48 hours. Scale bar, 50 μm. DAPI, 4′,6-diamidino-2-phenylindole; MVB, multivesicular body.

Enhancing Immunotherapy

Excitingly, studies have shown that co-administration of both types of nanoliposomes significantly improves the infiltration of cytotoxic T cells, which are crucial for mounting an effective immune response against cancer cells. This enhanced immune response, in turn, enhances the antitumor efficacy of immunotherapy, particularly αPD-L1, in immunocompetent lung cancer–bearing mice.

The discovery of the role of exosomes in the transformation of fibroblasts into CAFs has opened up new avenues for cancer therapy. By targeting this two-step process using nanoliposomes, researchers have demonstrated the potential to normalize CAFs and enhance the efficacy of immunotherapy. This promising approach holds the key to unlocking more effective treatments for cancer patients and improving outcomes in the fight against this devastating disease.

Freag MS, Mohammed MT, Kulkarni A, Emam HE, Maremanda KP, Elzoghby AO. (2024) Modulating tumoral exosomes and fibroblast phenotype using nanoliposomes augments cancer immunotherapy. Sci Adv 10(9):eadk3074. [article]

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