Antitumor adaptive immunity remains intact following inhibition of autophagy and antimalarial treatment
Hanna Starobinets, Jordan Ye, Miranda Broz, Kevin Barry, Juliet Goldsmith, Timothy Marsh, Fanya Rostker, Matthew Krummel, Jayanta Debnath
Hanna Starobinets, Jordan Ye, Miranda Broz, Kevin Barry, Juliet Goldsmith, Timothy Marsh, Fanya Rostker, Matthew Krummel, Jayanta Debnath
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Research Article Immunology Oncology

Antitumor adaptive immunity remains intact following inhibition of autophagy and antimalarial treatment

Abstract

The rising success of cancer immunotherapy has produced immense interest in defining the clinical contexts that may benefit from this therapeutic approach. To this end, there is a need to ascertain how the therapeutic modulation of intrinsic cancer cell programs influences the anticancer immune response. For example, the role of autophagy as a tumor cell survival and metabolic fitness pathway is being therapeutically targeted in ongoing clinical trials that combine cancer therapies with antimalarial drugs for the treatment of a broad spectrum of cancers, many of which will likely benefit from immunotherapy. However, our current understanding of the interplay between autophagy and the immune response remains incomplete. Here, we have evaluated how autophagy inhibition impacts the antitumor immune response in immune-competent mouse models of melanoma and mammary cancer. We observed equivalent levels of T cell infiltration and function within autophagy-competent and -deficient tumors, even upon treatment with the anthracycline chemotherapeutic doxorubicin. Similarly, we found equivalent T cell responses upon systemic treatment of tumor-bearing mice with antimalarial drugs. Our findings demonstrate that antitumor adaptive immunity is not adversely impaired by autophagy inhibition in these models, allowing for the future possibility of combining autophagy inhibitors with immunotherapy in certain clinical contexts.

Authors

Hanna Starobinets, Jordan Ye, Miranda Broz, Kevin Barry, Juliet Goldsmith, Timothy Marsh, Fanya Rostker, Matthew Krummel, Jayanta Debnath

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Figure 4

Transgenic OT-I cell activation is unchanged in autophagy-deficient OVA-expressing tumors.

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Transgenic OT-I cell activation is unchanged in autophagy-deficient OVA-...
Freshly isolated transgenic OT-I CD8+ T cells expressing GFP were adoptively transferred by retro-orbital injection into mice bearing 2-week subcutaneous autophagy-competent and -deficient B78 melanomas expressing OVA. (A) Primary tumor growth of autophagy-competent and -deficient subcutaneous B78-OVA tumors in syngeneic host mice as assessed by caliper measurements of tumor area (n = 5 per cohort). (B) Autophagy deficiency was confirmed in B78-OVA cells isolated from digested tumors by immunofluorescence for P62. Accumulation of P62 aggregates was quantified per cell nucleus. Error bars represent SD; **P < 0.01 using unpaired t test. (C) Total T cells were defined as the CD45+CD3+SSC-Alo fraction of live cells and were further subdivided into OT-I (GFP+) and endogenous (GFP–) populations; the latter was analyzed for CD4 and CD8 surface expression. Endogenous and OT-I T cell populations were equivalent between autophagy-competent (shCTL) and -deficient (shAtg12) B78-OVA tumors. Error bars represent SD with 2-way ANOVA not significant. (D) Activation status was measured by surface CD44 and intracellular IFN-γ, TNF-α, and GZMB expression in endogenous and OT-I T cell populations from autophagy-competent and -deficient B78-OVA tumors. Representative histograms of functional marker staining of endogenous and OT-I T cell populations: solid gray plots represent unstained controls (for surface staining of CD44) and isotype controls (for intracellular stains of IFN-γ, TNF-α, GZMB). Positive staining is defined as that above the unstained or isotype control and is indicated by gates. In graphs, each data point represents a distinct tumor from an individual host mouse, and bars represent mean values. ****P < 0.0001 using 2-way ANOVA multiplicity-adjusted P values (Dunnett’s correction).