Jian Gao

The Src homology 2 domain-containing tyrosine phosphatase 2 (SHP2) is a non-receptor tyrosine phosphatase and acts as a convergent node for oncogenic cell-signaling cascades. SHP2 has been recognized as a breakthrough anti-tumor therapeutic target. However, it is still elusive for the role of SHP2 in manipulating tumor microenvironment for malignancy. Here, we found that SHP2 activation in tumor-associated macrophages (TAMs) paralleled mammary carcinoma progression. Co-culture system and human breast cancer specimens also showed high levels of phosphorylated SHP2 in macrophages. Conditional SHP2 knockout or pharmacological SHP2 inhibition blocked mammary carcinoma growth and reduced metastasis. More importantly, tumor-derived IL-10 induced SHP2 phosphorylation in macrophages upon the tumor-macrophage interaction. SHP2 activation rendered macrophages an immunosuppressive phenotype and attenuated their responsiveness to type I interferon. IL-10 deficiency in mammary carcinoma cells caused tumor regression, which was accompanied by the reduction of SHP2 activation in TAMs. These findings suggest a protumorigenic role of SHP2 in the crosstalk between macrophages and mammary carcinoma cells in tumor microenvironments and reveal that targeting SHP2 in macrophages could be a therapeutic approach to improve anticancer therapy.

Hyaline cartilage fibrosis is typically considered an end-stage pathology of osteoarthritis (OA), which results in changes to the extracellular matrix. However, the mechanism behind this is largely unclear. Here, we found that the RNA helicase DDX5 was dramatically downregulated during the progression of OA. DDX5 deficiency increased fibrosis phenotype by upregulating COL1 expression and downregulating COL2 expression. In addition, loss of DDX5 aggravated cartilage degradation by inducing the production of cartilage-degrading enzymes. Chondrocyte-specific deletion of Ddx5 led to more severe cartilage lesions in the mouse OA model. Mechanistically, weakened DDX5 resulted in abundance of the Fn1-AS-WT and Plod2-AS-WT transcripts, which promoted expression of fibrosis-related genes (Col1, Acta2) and extracellular matrix degradation genes (Mmp13, Nos2 and so on), respectively. Additionally, loss of DDX5 prevented the unfolding Col2 promoter G-quadruplex, thereby reducing COL2 production. Together, our data suggest that strategies aimed at the upregulation of DDX5 hold significant potential for the treatment of cartilage fibrosis and degradation in OA.

Summary: Neutrophils are the most abundant innate immune cells in human blood, emerging as important players in a variety of diseases. Mitochondria are bioenergetic, biosynthetic, and signaling organelles critical for cell fate and function. Mitochondria have been overlooked in neutrophil research owing to the conventional view that neutrophils contain few, if any, competent mitochondria and do not rely on these organelles for adenosine triphosphate production. A growing body of evidence suggests that mitochondria participate in neutrophil biology at many levels, ranging from neutrophil development to chemotaxis, effector function, and cell death. Moreover, mitochondria and mitochondrial components, such as mitochondrial deoxyribonucleic acid, can be released by neutrophils to eliminate infection and/or shape immune response, depending on the specific context. In this review, we provide an update on the functional role of mitochondria in neutrophils, highlight mitochondria as key players in modulating the neutrophil phenotype and function during infection and inflammation, and discuss the possibilities and challenges to exploit the unique aspects of mitochondria in neutrophils for disease treatment.

Background and purpose: Continuous efforts have been made to move towards maintaining the beneficial anti‐inflammatory functions of glucocorticoids (GCs) while minimizing side effects. Here, we investigated the selective glucocorticoid receptor (GR) modulator‐like properties of a plant‐derived compound caesaldekarin e (CA‐e).Experimental approach: The therapeutic efficacy of CA‐e was evaluated in several mouse models, including dextran sulfate sodium‐induced colitis, ovalbumin‐induced lung allergic inflammation, imiquimod‐induced psoriasis‐like skin inflammation and skin atrophy. The action of CA‐e targeting the GR was analysed using molecular docking, cellular thermal shift assays and microscale thermophoresis. Other methods included DNA–protein pull‐down assays and mass spectrometry.Key results: CA‐e selectively inhibited positive GC response element ((+) GRE)‐mediated direct transactivation while maintaining and even enhancing the anti‐inflammatory effects of treatment with dexamethasone. CA‐e, alone and in combination with dexamethasone, efficiently alleviated inflammation in several mouse models with milder side effects compared with dexamethasone alone. Mechanistically, CA‐e inhibited the formation of dimers by binding to the dimerization interface located in the ligand‐binding domain of GR and facilitated embryonic ectoderm development that is involved in the regulation of transcriptional repression to compete for binding to (+) GRE, eventually leading to the repression of (+) GRE‐regulated genes. In addition, CA‐e repressed NF‐κB‐dependent genes by enhancing the interaction between GR and p65.Conclusions and implications: Our results reveal that CA‐e is a novel GR modulator with strong potency to attenuate the side effects of GC therapy and can be used as a potential molecular tool for deciphering GR signalling.

Loss-of-function mutations frequently occur in tumor suppressor genes, i.e., p53, during the malignant progression of various cancers. Whether any intrinsic suppressor carries a rare mutation is largely unknown. Here, we demonstrate that intracellular cytokine-like protein 1 (CYTL1) plays a key role in preventing the robust glycolytic switching characteristic of breast cancer. A low intracellular CYTL1 level, not its mutation, is required for metabolic reprogramming. Breast cancer cells expressing an intracellular form of CYTL1 lacking a 1-22 aa signal peptide, ΔCYTL1, show significantly attenuated glucose uptake and lactate production, which is linked to the inhibition of cell growth and metastasis in vitro and in vivo. Mechanistically, CYTL1 competitively binds the N-terminal sequence of NDUFV1 to block MDM2-mediated degradation by the proteasome, leading to the stability of the NDUFV1 protein. In addition to inducing increased NAD⁺ levels, NDUFV1 interacts with Src to attenuate LDHA phosphorylation at tyrosine 10 and reduce lactate production. Our results reveal, for the first time, that CYTL1 is a novel tumor suppressor. Its function in reversing metabolic reprogramming toward glycolysis may be very important for the development of novel antitumor strategies.

Breast cancer is a heterogeneous disease that includes different molecular subtypes. The basal-like subtype has a poor prognosis and a high recurrence rate, whereas the luminal-like subtype confers a more favorable patient prognosis partially due to anti-hormone therapy responsiveness. Here, we demonstrate that diptoindonesin G (Dip G), a natural product, exhibits robust differentiation-inducing activity in basal-like breast cancer cell lines and animal models. Specifically, Dip G treatment caused a partial transcriptome shift from basal to luminal gene expression signatures and prompted sensitization of basal-like breast tumors to tamoxifen therapy. Dip G upregulated the expression of both GABARAPL1 (GABA_A receptor-associated protein-like 1) and ERβ. We revealed a previously unappreciated role of GABARAPL1 as a regulator in the specification of breast cancer subtypes that is dependent on ERβ levels. Our findings shed light on new therapeutic opportunities for basal-like breast cancer via a phenotype switch and indicate that Dip G may serve as a leading compound for the therapy of basal-like breast cancer.

Introduction: Exosomes are important mediators of intercellular communication. Previously, we characterized circulating exosomal miR-425-3p as a non-invasive prognostic marker for predicting clinical response to platinum-based chemotherapy in patients with non-small cell lung cancer (NSCLC). Methods: Circulating exosomal miR-425-3p was validated by qRT-PCR in paired serum samples from NSCLC patients during the course of platinum-based chemotherapy. Cell coculture was performed to examine the effects of exosomal miR-425-3p on the sensitivity of recipient A549 cells to cisplatin. Using bioinformatics, ChIP and luciferase reporter assays, the transcription factor essential for miR-425-3p expression was identified. Autophagic activity in the recipient cells was determined by Western blot and fluorescence microscopy. Results: Higher levels of exosomal miR-425-3p were found in serum samples from the patients in tolerance versus those at baseline. An upward trend in the expression of circulating exosomal miR-425-3p was revealed during chemotherapy. Furthermore, the expression of exosomal miR-425-3p could be induced by cisplatin in NSCLC cells. Exosomes isolated from either cisplatin-treated or cisplatin-resistant NSCLC cells conferred chemoresistance to sensitive A549 cells in a miR-425-3p-dependent manner. Cisplatin-induced c-Myc was found to directly bind the miR-425-3p promoter and transactivated its expression. Exosomal miR-425-3p facilitated autophagic activation in the recipient cells by targeting AKT1, eventually leading to chemoresistance. Discussion: Our results suggest that apart from a prognostic marker of treatment response, exosomal miR-425-3p might be a potential dynamic biomarker to tailor cisplatin resistance in NSCLC patients during the treatment and represent a promising therapeutic target for therapy-resistant NSCLC.

Background and Purpose: Accumulating evidence indicates that mitochondrial dynamics play an important role in the progressive deterioration of dopaminergic neurons. Andrographolide has been found to exert neuroprotective effects in several models of neurological diseases. However, the mechanism of how andrographolide protects neurons in Parkinson's disease (PD) remains not fully understood.Experimental Approach: Behavioural experiments were performed to examine the effect of andrographolide in 1‐Methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine (MPTP)‐PD mice. Mitochondrial mass and morphology were visualized using transmission electron microscopy (TEM). SH‐SY5Y cells and primary mouse neurons were exposed to rotenone to mimic PD in vitro. Western blotting, co‐immunoprecipitation and immunofluorescence were performed. The target protein of andrographolide was identified by biotin‐andrographolide pulldown assay as well as drug affinity responsive target stability (DARTS), cellular thermal shift (CETSA), and surface plasmon resonance (SPR) assays.Key Results: Andrographolide administration improved behavioural deficits and attenuated loss of dopaminergic neurons in MPTP‐exposed mice and reduced cell death induced by rotenone in vitro. An increased mitochondrial mass, and decreased surface area were found in the striatum from MPTP‐PD mice, as well as in rotenone‐treated primary neurons and SH‐SY5Y cells, while andrographolide treatment preserved mitochondrial mass and morphology. Dynamin‐related protein 1 (DRP1) was identified as a target protein of andrographolide. Andrographolide bound to DRP1 and inhibited its GTPase activity, thereby preventing excessive mitochondria fission and neuronal damage in PD.Conclusions and Implications: Our findings suggest that andrographolide may protect neurons against rotenone‐ or MPTP‐induced damage in vitro and in vivo through inhibiting mitochondrial fission.