Disrupting Smad3 potentiates immunostimulatory function of NK cells against lung carcinoma by promoting GM-CSF production.

Through Smad3-dependent signalings, transforming growth factor-ß (TGF-ß) suppresses the development, maturation, cytokine productions and cytolytic functions of NK cells in cancer. Silencing Smad3 remarkably restores the cytotoxicity of NK-92 against cancer in TGF-ß-rich microenvironment, but its effects on the immunoregulatory functions of NK cells remain obscure. In this study, we identified Smad3 functioned as a transcriptional repressor for CSF2 (GM-CSF) in NK cells. Therefore, disrupting Smad3 largely mitigated TGF-ß-mediated suppression on GM-CSF production by NK cells. Furthermore, silencing GM-CSF in Smad3 knockout NK cells substantially impaired their anti-lung carcinoma effects. In-depth study demonstrated that NK-derived GM-CSF strengthened T cell immune responses by stimulating dendritic cell differentiation and M1 macrophage polarization. Meanwhile, NK-derived GM-CSF promoted the survival of neutrophils, which in turn facilitated the terminal maturation of NK cells, and subsequently boosted NK-cell mediated cytotoxicity against lung carcinoma. Thus, Smad3-silenced NK-92 (NK-92-S3KD) may serve as a promising immunoadjuvant therapy with clinical translational value given its robust cytotoxicity against malignant cells and immunostimulatory functions to reinforce the therapeutic effects of other immunotherapies.

Challenges and Recent Advances in NK Cell-Targeted Immunotherapies in Solid Tumors.

Natural killer (NK) cell is a powerful malignant cells killer, providing rapid immune responses via direct cytotoxicity without the need of antigen processing and presentation. It plays an essential role in preventing early tumor, metastasis and minimal residual disease. Although adoptive NK therapies achieved great success in clinical trials against hematologic malignancies, their accumulation, activation, cytotoxic and immunoregulatory functions are severely impaired in the immunosuppressive microenvironment of solid tumors. Now with better understandings of the tumor evasive mechanisms from NK-mediated immunosurveillance, immunotherapies targeting the key molecules for NK cell dysfunction and exhaustion have been developed and tested in both preclinical and clinical studies. In this review, we introduce the challenges that NK cells encountered in solid tumor microenvironment (TME) and the therapeutic approaches to overcome these limitations, followed by an outline of the recent preclinical advances and the latest clinical outcomes of NK-based immunotherapies, as well as promising strategies to optimize current NK-targeted immunotherapies for solid tumors.

Macrophages in Renal Fibrosis.

Monocytes/macrophages are highly involved in the process of renal injury, repair and fibrosis in many aspects of experimental and human renal diseases. Monocyte-derived macrophages, characterized by high heterogeneity and plasticity, are recruited, activated, and polarized in the whole process of renal fibrotic diseases in response to local microenvironment. As classically activated M1 or CD11b+/Ly6Chigh macrophages accelerate renal injury by producing pro-inflammatory factors like tumor necrosis factor-alpha (TNFα) and interleukins, alternatively activated M2 or CD11b+/Ly6Cintermediate macrophages may contribute to kidney repair by exerting anti-inflammation and wound healing functions. However, uncontrolled M2 macrophages or CD11b+/Ly6Clow macrophages promote renal fibrosis via paracrine effects or direct transition to myofibroblast-like cells via the process of macrophage-to-myofibroblast transition (MMT). In this regard, therapeutic strategies targeting monocyte/macrophage recruitment, activation, and polarization should be emphasized in the treatment of renal fibrosis.

Transforming growth factor-ß signalling in renal fibrosis: from Smads to non-coding RNAs.

Transforming growth factor-ß (TGF-ß) is the key player in tissue fibrosis. However, antifibrotic therapy targeting this multifunctional protein may interfere with other physiological processes to cause side effects. Thus, precise therapeutic targets need to be identified by further understanding the underlying mechanisms of TGF-ß1 signalling during fibrogenesis. Equilibrium of Smad signalling is crucial for TGF-ß-mediated renal fibrosis, where Smad3 is pathogenic but Smad2 and Smad7 are protective. The activation of TGF-ß1/Smad signalling triggers extracellular matrix deposition, and local myofibroblast generation and activation. Mechanistic studies have shown that TGF-ß/Smad3 transits the microRNA profile from antifibrotic to profibrotic and therefore promotes renal fibrosis via regulating non-coding RNAs at transcriptional levels. More importantly, disease-specific Smad3-dependent long non-coding RNAs have been recently uncovered from mouse kidney disease models and may represent novel precision therapeutic targets for chronic kidney disease. In this review, mechanisms of TGF-ß-driven renal fibrosis via non-coding RNAs and their translational capacities will be discussed in detail.

Self-carried nanodrug (SCND-SIS3): A targeted therapy for lung cancer with superior biocompatibility and immune boosting effects.

Transforming growth factor ß (TGF-ß) is a well-known key mediator for the progression and metastasis of lung carcinoma. However, cost-effective anti-TGF-ß therapeutics for lung cancer remain to be explored. Specifically, the low efficacy in drug delivery greatly limits the clinical application of small molecular inhibitors of TGF-ß. In the present study, specific inhibitor of Smad3 (SIS3) is developed into a self-carried nanodrug (SCND-SIS3) using the reprecipitation method, which largely improves its solubility and bioavailability while reduces its nephrotoxicity. Compared to unmodified-SIS3, SCND-SIS3 demonstrates better anti-cancer effects through inducing tumor cell apoptosis, inhibiting angiogenesis, and boosting NK cell-mediated immune responses in syngeneic Lewis Lung Cancer (LLC) mouse model. Better still, it could achieve comparable anti-cancer effect with just one-fifth the dose of unmodified-SIS3. Mechanistically, RNA-sequencing analysis and cytokine array results unveil a TGF-ß/Smad3-dependent immunoregulatory landscape in NK cells. In particular, SCND-SIS3 promotes NK cell cytotoxicity by ameliorating Smad3-mediated transcriptional inhibition of Ndrg1. Furthermore, improved NK cell cytotoxicity by SCND-SIS3 is associated with higher expression of activation receptor Nkp46, and suppressed levels of Trib3 and TSP1 as compared with unmodified-SIS3. Taken together, SCND-SIS3 possesses superior anti-cancer effects with enhanced bioavailability and biocompatibility, therefore representing as a novel therapeutic strategy for lung carcinoma with promising clinical potential.

Inhibition of tumor invasion and metastasis by targeting TGF-ß-Smad-MMP2 pathway with Asiatic acid and Naringenin.

Transforming growth factor ß (TGF-ß) has been shown to promote tumor invasion and metastasis by activating the matrix metalloproteinases (MMPs); however, signaling mechanisms remain controversial and therapies targeting MMPs are still suboptimal. In the present study, we found that combined therapy with Asiatic acid (AA), a Smad7 agonist, and Naringenin (NG), a Smad3 inhibitor, effectively retrieved the balance between Smad3 and Smad7 signaling in the TGF-ß-rich tumor microenvironment and thus significantly suppressed tumor invasion and metastasis in mouse models of melanoma and lung carcinoma. Mechanistically, we unraveled that Smad3 acted as a transcriptional activator of MMP2 and as a transcriptional suppressor of tissue inhibitors of metalloproteinase-2 (TIMP2) via binding to 5' UTR of MMP2 and 3' UTR of TIMP2, respectively. Treatment with NG inhibited Smad3-mediated MMP2 transcription while increasing TIMP, whereas treatment with AA enhanced Smad7 to suppress TGF-ß/Smad3 signaling, as well as the activation of MMP2 by targeting the nuclear factor-κB (NF-κB)-membrane-type-1 MMP (MT1-MMP) axis. Therefore, the combination of AA and NG additively suppressed invasion and metastasis of melanoma and lung carcinoma by targeting TGF-ß/Smad-dependent MMP2 transcription, post-translational activation, and function.