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Generation of a Novel Dendritic-cell Vaccine Using Melanoma and Squamous Cancer Stem Cells
Published on: January 6, 2014
[Unveiling antigens in a non-immunogenic spontaneous murine tumor using a dendritic cell based vaccine]
Verónica L Reffo1, Paula Chiarella, Juan Bruzzo
1División Medicina Experimental, ILEX-CONICET, Instituto de Investigaciones Hematológicas, Academia Nacional de Medicina, Buenos Aires.
Abstract:
Up to date, most attempts to use immunotherapy to cause the regression of animal and human established tumors have not been successful. Former experiments have postulated that this failure could be attributed, at least in part, to a lack of immunogenicity of spontaneous tumors. In this paper, we have investigated whether this lack of immunogenicity can be attributed to the absence of tumor antigens or to the existence of tolerogenic mechanisms preventing such antigens from initiating an antitumor immune response. We have used two murine tumors a non-immunogenic spontaneous lymphoma (LB) and a strongly immunogenic methylcholanthrene-induced fibrosarcoma (MC-C) together with a vaccination strategy based on the inoculation of dendritic cells (DC) loaded with a tumor lysate. When DC were pulsed with LB lysate (DC+LB), no maturation of DC was achieved in vitro and no protection against LB implants after DC+LB inoculation was observed in vivo. On the other hand, when DC were pulsed with MC-C lysate (DC+MC-C), maturation of DC was observed along with a strong protection against MC-C implants after DC+MC-C inoculaton. Finally, when DC were pulsed with both LB and MC-C lysates (DC+LB+MC-C), maturation of DC and protection against LB implants were achieved. Since no immune cross reaction between MC-C and LB was ever observed, the most likely interpretation is that LB bears specific tumor antigens but lacks other signals to achieve DC maturation. These signals would be provided by MC-C which would enable DC to mature and to initiate an effective anti-LB immune response.
Insights
Immunotherapy often fails against established tumors due to lack of immunogenicity. Combining tumor lysates with dendritic cells (DC) can overcome this, enabling anti-tumor immune responses against previously unresponsive tumors.
Area of Science:
- Immunology
- Cancer Research
- Tumor Microenvironment
Context:
- Established tumor regression via immunotherapy remains a significant challenge.
- Spontaneous tumors often exhibit low immunogenicity, hindering effective anti-tumor immune responses.
- Understanding tumor antigenicity and immune evasion mechanisms is crucial for developing novel cancer therapies.
Purpose:
- To investigate the reasons behind the lack of immunogenicity in spontaneous tumors.
- To explore the potential of dendritic cell (DC) based vaccination strategies loaded with tumor lysates for overcoming tumor-induced immune tolerance.
- To determine if co-presentation of antigens from an immunogenic tumor can induce maturation of DCs and elicit an anti-tumor immune response against a non-immunogenic tumor.
Summary:
- Experiments using murine models showed that dendritic cells (DCs) pulsed with a non-immunogenic lymphoma (LB) lysate failed to mature or induce protection.
- Conversely, DCs pulsed with a methylcholanthrene-induced fibrosarcoma (MC-C) lysate matured and provided protection against MC-C tumors.
- Crucially, co-pulsing DCs with both LB and MC-C lysates induced DC maturation and protection against LB tumors, suggesting MC-C provided necessary co-stimulatory signals.
Impact:
- This study reveals that spontaneous tumors may possess antigens but lack signals for dendritic cell (DC) maturation, leading to immune evasion.
- The findings suggest that combining antigens from immunogenic and non-immunogenic tumors could be a viable strategy to enhance DC maturation and initiate effective anti-tumor immunity.
- This approach holds promise for improving the efficacy of immunotherapy against previously resistant established tumors.
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