Project description:CDK4/6 inhibitors are approved to treat breast cancer and are in trials for other malignancies. We examined CDK4/6 inhibition in mouse and human CD8+ T cells during early stages of activation. Mice receiving tumor-specific CD8+ T cells treated with CDK4/6 inhibitors displayed increased T-cell persistence and immunologic memory. CDK4/6 inhibition upregulated MXD4, a negative regulator of MYC, in both mouse and human CD8+ T cells. Silencing of Mxd4 or Myc in mouse CD8+ T cells demonstrated the importance of this axis for memory formation. We used single-cell transcriptional profiling and T-cell receptor clonotype tracking to evaluate recently activated human CD8+ T cells in patients with breast cancer before and during treatment with either palbociclib or abemaciclib. CDK4/6 inhibitor therapy in humans increases the frequency of CD8+ memory precursors and downregulates their expression of MYC target genes, suggesting that CDK4/6 inhibitors in patients with cancer may augment long-term protective immunity. SIGNIFICANCE: CDK4/6 inhibition skews newly activated CD8+ T cells toward a memory phenotype in mice and humans with breast cancer. CDK4/6 inhibitors may have broad utility outside breast cancer, particularly in the neoadjuvant setting to augment CD8+ T-cell priming to tumor antigens prior to dosing with checkpoint blockade.This article is highlighted in the In This Issue feature, p. 2355.
Project description:Sensing of extracellular metabolites controls CD8+ T cell function. Their accumulation can occur through export by specialized molecules, such as the release channel Pannexin-1 (Panx1). Here, we report that T cell-specific Panx1 is needed for efficient CD8+ T cell responses to viral infection and cancer. Panx1 favors both the expansion of effector CD8+ T cells and the survival of memory CD8+ T cells. Our data suggests that, while memory CD8+ T cells require Panx1 for mitochondrial function, Panx1 promotes the glycolytic pathway in effector CD8+ T cells. Panx1 promotes memory CD8+ T cell survival together with the eATP sensor P2RX7. However, Panx1 induces effector CD8+ T cells independently of eATP. Rather, we found an unexpected link between Panx1, sodium lactate export and the activation of effector CD8+ T cells. Therefore, Panx1 regulates effector and memory CD8+ T cells through export of distinct metabolites and by engaging different intracellular pathways.
Project description:Sensing of extracellular metabolites controls CD8+ T cell function. Their accumulation can occur through export by specialized molecules, such as the release channel Pannexin-1 (Panx1). Here, we report that T cell-specific Panx1 is needed for efficient CD8+ T cell responses to viral infection and cancer. Panx1 favors both the expansion of effector CD8+ T cells and the survival of memory CD8+ T cells. Our data suggests that, while memory CD8+ T cells require Panx1 for mitochondrial function, Panx1 promotes the glycolytic pathway in effector CD8+ T cells. Panx1 promotes memory CD8+ T cell survival together with the eATP sensor P2RX7. However, Panx1 induces effector CD8+ T cells independently of eATP. Rather, we found an unexpected link between Panx1, sodium lactate export and the activation of effector CD8+ T cells. Therefore, Panx1 regulates effector and memory CD8+ T cells through export of distinct metabolites and by engaging different intracellular pathways.
Project description:Pharmacologicalinhibitors of cyclin dependent kinases 4 and 6 (CDK4/6) are an approvedtreatment forhormone receptor-positive breast cancer and are currently under evaluation across hundreds of clinical trials for other cancertypes. The clinical success of these inhibitorsis largely attributedto well-defined tumor-intrinsic cytostatic mechanisms, while their emerging role as immunomodulatory agents is lessunderstood. Usingintegrated epigenomic, transcriptomic and proteomicanalyses, we demonstrateda novel action of CDK4/6inhibitorsin promoting the phenotypic and functional acquisition of immunological T cell memory.Short-term priming with a CDK4/6inhibitorpromoted long-termendogenousanti-tumor T cell immunityin mice, enhanced the persistence and therapeutic efficacy of chimeric antigen receptor (CAR)-T cells, and induced an RB-dependent T cell phenotype supportive offavorable responses to immune checkpoint blockade in melanoma patients.Together, thesemechanistic insights significantlybroaden the prospective utility of CDK4/6 inhibitors as clinical tools to boostanti-tumorT cell immunity.
Project description:T cells receive numerous positive and negative signals during primary antigen encounter that control their proliferation and function, but how these signals are integrated to modulate T cell memory has not been fully characterized. In these studies, we demonstrate that combining seemingly opposite signals, CTLA-4 blockade and rapamycin-mediated mTOR inhibition, during in vivo T cell priming leads to both an increase in the frequency of memory CD8+ T cells and improved memory responses to tumors and bacterial challenges. This enhanced efficacy corresponds to increased early expansion and memory precursor differentiation of CD8+ T cells and increased mitochondrial biogenesis and spare respiratory capacity in memory CD8+ T cells in mice treated with anti-CTLA-4 and rapamycin during immunization. Collectively, these results reveal that mTOR inhibition cooperates with rather than antagonizes blockade of CTLA-4, promoting unrestrained effector function and proliferation and an optimal metabolic program for CD8+ T cell memory. Total RNA was isolated from FACS-sorted, antigen-specific CD8+T cells from different treatment conditions at 5 or 35 days after primary T cell activation
Project description:Memory CD8+ T cells are indispensable for maintaining long-term immunity against intracellular pathogens and tumors. Despite their presence in oxygen-deprived tissues of infection sites or tumors, the impact of local oxygen pressure on memory CD8+ T cells has remained largely unclear. We sought to elucidate how oxygen pressure impacted memory CD8+ T cells arising after infection with Listeria monocytogenes-OVA. Our data revealed that reduced oxygen pressure during in vitro culture switched CD8+ T cell metabolism from an OXPHOS to a glycolytic phenotype. Quantitative proteomic analysis showed that limiting oxygen conditions increased the expression of glucose transporters and components of the glycolytic pathway, while decreasing TCA cycle and mitochondrial respiratory chain proteins. The altered CD8+ T cell metabolism did not affect the expansion potential, but enhanced the granzyme B and IFN- production capacity. Memory CD8+ T cells cultured under low oxygen pressure were able to persist long-term in vivo and provided protection against bacterial rechallenge. Taken together, our study indicates that strategies of cellular immune therapy may benefit from reducing oxygen during culture to develop memory CD8+ T cells with superior effector functions .
Project description:CDK4 inhibitors have reached clinical approval for cancer therapy. In parallel, the p53 antagonist Mdm2 remains an attractive target for anti-cancer therapy, including numerous clinical studies. The genes encoding Mdm2 and CDK4 are frequently co-amplified in human malignancies, most notably in liposarcomas, suggesting their combined targeting for therapy. Here we show, however, that small compounds that inhibit Mdm2 and CDK4 antagonize each other rather than synergize in their cytotoxicity towards sarcoma cells. CDK4 inhibition attenuates the induction of p53-responsive genes upon Mdm2 inhibition, and similar results were obtained when depleting Mdm2 and/or CDK4 with siRNA. CDK4 inhibitors also interfered with p53 activity in response to DNA damage. CDK4 inhibition did not reduce p53 binding or histone acetylation to promoters, but rather attenuated the subsequent recruitment of RNA polymerase II. The complexes of p53 and Mdm2, as well as CDK4 and Cyclin D1, physically associated with each other. Upon combined inhibition of Mdm2 and CDK4/6, the interaction of this complex was impaired. Thus, the CDK4-Cyclin D1 complex plays a key role in enabling the transcription of p53 target genes. Taken together, our results raise caution regarding the combination of CDK4 inhibitors with Mdm2 antagonists or conventional DNA-damaging chemotherapeutics in the clinics. Moreover, they suggest a hitherto unknown role for CDK4-cyclin D1 complex in sustaining p53 activity, possibly focusing p53-mediated transcription on actively proliferating cells.