The clinical success of immunotherapy that inhibits the negative immune regulatory pathway programmed cell death protein 1/PD-1 ligand (PD-1/PD-L1) has initiated a new era in the treatment of metastatic cancer. PD-L1 expression is upregulated in many solid tumors including lung cancer and functions predominantly in lactate-enriched tumor microenvironments. Here, we provided evidence for PD-L1 induction in response to lactate stimulation in lung cancer cells. Lactate-induced PD-L1 induction was mediated by its receptor GPR81. The silencing of GPR81 signaling in lung cancer cells resulted in a decrease in PD-L1 protein levels and functional inactivation of PD-L1 promoter activity. In addition, GPR81-mediated upregulation of PD-L1 in glucose-stimulated lung cancer cells that recapitulates the enhanced glycolysis in vivo was dependent on lactate dehydrogenase A (LDHA). We also demonstrated that activation of GPR81 decreases intracellular cAMP levels and inhibits protein kinase A (PKA) activity, leading to activation of the transcriptional coactivator TAZ. Interaction of TAZ with the transcription factor TEAD was essential for TAZ activation of PD-L1 and induction of its expression. Furthermore, we found that lactate-induced activation of PD-L1 in tumor cells led to reduced production of interferon-γ and induction of apoptosis of cocultured Jurkat T-cell leukemia cells. Our findings reveal an unexpected role of lactate in contributing to tumor cell protection from cytotoxic T-cell targeting and establishes a direct connection between tumor cell metabolic reprograming and tumor evasion from the immune response.

An ideal cancer therapeutic strategy is expected to possess potent ability to not only ablate primary tumors but also prevent distance metastasis and relapse. In this study, human serum albumin was hybridized with hemoglobin by intermolecular disulfide bonds to develop a hybrid protein oxygen nanocarrier with chlorine e6 encapsulated (C@HPOC) for oxygen self-sufficient photodynamic therapy (PDT). C@HPOC realized the tumor-targeted co-delivery of photosensitizer and oxygen, which remarkably relieved tumor hypoxia. C@HPOC was favorable for more efficient PDT and enhanced infiltration of CD8 T cells in tumors. Moreover, oxygen-boosted PDT of C@HPOC induced immunogenic cell death, with the release of danger-associated molecular patterns to activate dendritic cells, T lymphocytes, and natural killer cells in vivo. Notably, C@HPOC-mediated immunogenic PDT could destroy primary tumors and effectively suppress distant tumors and lung metastasis in a metastatic triple-negative breast cancer model by evoking systemic anti-tumor immunity. This study provides a paradigm of oxygen-augmented immunogenic PDT for metastatic cancer treatment.

SUMMARY Mitochondrion plays essential roles in many aspects of biology, and its dysfunction has been linked to diverse diseases. Central to mitochondrial function is oxidative phosphorylation (OXPHOS), accomplished by respiratory chain complexes (RCCs) encoded by nuclear and mitochondrial genomes. How RCC biogenesis is regulated in metazoans is poorly understood. Here we show that Parkinson’s disease (PD)-associated genes PINK1 and Parkin direct localized translation of certain nuclear-encoded RCC (nRCC) mRNAs. Translationally-repressed nRCC mRNAs are localized in a PINK1/Tom20-dependent manner to mitochondrial outer membrane, where they are de-repressed and activated by PINK1/Parkin through displacement of translation repressors, including Pumilio and Glorund/hnRNP-F, a Parkin substrate, and enhanced binding of activators such as eIF4G. Inhibiting the translation repressors rescued nRCC mRNA translation and neuromuscular-degeneration phenotypes of PINK1 mutant, whereas inhibiting eIF4G had opposite effects. Our results reveal previously unknown functions of PINK1/Parkin in RNA metabolism and suggest new approaches to mitochondrial restoration and disease intervention.

No abstract

Calcium (Ca) homeostasis is essential for neuronal function and survival. Altered Ca homeostasis has been consistently observed in neurological diseases. How Ca homeostasis is achieved in various cellular compartments of disease-relevant cell types is not well understood. Here we show in Parkinson's disease (PD) models that Ca transport from the endoplasmic reticulum (ER) to mitochondria through the ER-mitochondria contact site (ERMCS) critically regulates mitochondrial Ca (mito-Ca) homeostasis in dopaminergic (DA) neurons, and that the PD-associated PINK1 protein modulates this process. In mutant DA neurons, the ERMCS is strengthened and mito-Ca level is elevated, resulting in mitochondrial enlargement and neuronal death. Miro, a well-characterized component of the mitochondrial trafficking machinery, mediates the effects of PINK1 on mito-Ca and mitochondrial morphology, apparently in a transport-independent manner. Miro overexpression mimics loss-of-function effect, whereas inhibition of Miro or components of the ERMCS, or pharmacological modulation of ERMCS function, rescued mutant phenotypes. Mito-Ca homeostasis is also altered in the LRRK2-G2019S model of PD and the PAR-1/MARK model of neurodegeneration, and genetic or pharmacological restoration of mito-Ca level is beneficial in these models. Our results highlight the importance of mito-Ca homeostasis maintained by Miro and the ERMCS to mitochondrial physiology and neuronal integrity. Targeting this mito-Ca homeostasis pathway holds promise for a therapeutic strategy for neurodegenerative diseases.

No abstract

Metal complexes are widely used as anticancer drugs, while the severe side effects of traditional chemotherapy require new therapeutic modalities. Sonodynamic therapy (SDT) provides a significantly noninvasive ultrasound (US) treatment approach by activating sonosensitizers and initiating reactive oxygen species (ROS) to damage malignant tissues. In this work, three metal 4‐methylphenylporphyrin (TTP) complexes (MnTTP, ZnTTP, and TiOTTP) are synthesized and encapsulated with human serum albumin (HSA) to form novel nanosonosensitizers. These nanosonosensitizers generate abundant singlet oxygen (1O2) under US irradiation, and importantly show excellent US‐activatable abilities with deep‐tissue depths up to 11 cm. Compared to ZnTTP‐HSA and TiOTTP‐HSA, MnTTP‐HSA exhibits the strongest ROS‐activatable behavior due to the lowest highest occupied molecular orbital−lowest unoccupied molecular orbital gap energy by density functional theory. It is also effective for deep‐tissue photoacoustic/magnetic resonance dual‐modal imaging to trace the accumulation of nanoparticles in tumors. Moreover, MnTTP‐HSA intriguingly achieves high SDT efficiency for simultaneously suppressing the growth of bilateral tumors away from ultrasound source in mice. This work develops a deep‐tissue imaging‐guided SDT strategy through well‐defined metalloporphyrin nanocomplexes and paves a new way for highly efficient noninvasive SDT treatments of malignant tumors.

No abstract