Mutations in or dys-regulation of the TDP-43 gene have been associated with TDP-43 proteinopathy, a spectrum of neurodegenerative diseases including Frontotemporal Lobar Degeneration (FTLD) and Amyotrophic Lateral Sclerosis (ALS). The underlying molecular and cellular defects, however, remain unclear. Here, we report a systematic study combining analyses of patient brain samples with cellular and animal models for TDP-43 proteinopathy. Electron microscopy (EM) analyses of patient samples revealed prominent mitochondrial impairment, including abnormal cristae and a loss of cristae; these ultrastructural changes were consistently observed in both cellular and animal models of TDP-43 proteinopathy. In these models, increased TDP-43 expression induced mitochondrial dysfunction, including decreased mitochondrial membrane potential and elevated production of reactive oxygen species (ROS). TDP-43 expression suppressed mitochondrial complex I activity and reduced mitochondrial ATP synthesis. Importantly, TDP-43 activated the mitochondrial unfolded protein response (UPR mt ) in both cellular and animal models. Down-regulating mitochondrial protease LonP1 increased mitochondrial TDP-43 levels and exacerbated TDP-43-induced mitochondrial damage as well as neurodegeneration. Together, our results demonstrate that TDP-43 induced mitochondrial impairment is a critical aspect in TDP-43 proteinopathy. Our work has not only uncovered a previously unknown role of LonP1 in regulating mitochondrial TDP-43 levels, but also advanced our understanding of the pathogenic mechanisms for TDP-43 proteinopathy. Our study suggests that blocking or reversing mitochondrial damage may provide a potential therapeutic approach to these devastating diseases.

Forkheadbox protein 3 (FOXP3), initially identified as a key transcription factor for regulatory T cells (Treg cells), was also expressed in many tumors including pancreatic ductal adenocarcinoma (PDAC). However, its role in PDAC progression remains elusive. In this study, we utilized 120 PDAC tissues after radical resection to detect cancer-FOXP3 and Treg cells by immunohistochemistry and evaluated clinical and pathological features of these patients. Cancer-FOXP3 was positively correlated with Treg cells accumulation in tumor tissues derived from PDAC patients. In addition, high cancer-FOXP3 expression was associated with increased tumor volumes and poor prognosis in PDAC especially combined with high levels of Treg cells. Overexpression of cancer-FOXP3 promoted the tumor growth in immunocompetent syngeneic mice but not in immunocompromised or Treg cell-depleted mice. Furthermore, CCL5 was directly trans-activated by cancer-FOXP3 and promoted the recruitment of Treg cells from peripheral blood to the tumor site in vitro and in vivo. This finding has been further reinforced by the evidence that Treg cells recruitment by cancer-FOXP3 was impaired by neutralization of CCL5, thereby inhibiting the growth of PDAC. In conclusion, cancer-FOXP3 serves as a prognostic biomarker and a crucial determinant of immunosuppressive microenvironment via recruiting Treg cells by directly trans-activating CCL5. Therefore, cancer-FOXP3 could be used to select patients with better response to CCL5/CCR5 blockade immunotherapy.

Background: The tumor microenvironment (TME) consists of heterogeneous cell populations, including malignant cells and nonmalignant cells that support tumor proliferation, invasion, and metastasis through extensive cross talk. The intra-tumor immune landscape is a critical factor influencing patient survival and response to immunotherapy. Methods: Gene expression data were downloaded from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus databases. Immune cell infiltration was determined by single-sample Gene Set Enrichment Analysis (ssGSEA) depending on the integrated immune gene sets from published studies. Univariate analysis was used to determine the prognostic value of the infiltrated immune cells. Least absolute shrinkage and selection operator (LASSO) regression was performed to screen for the most survival-relevant immune cells. An immune-cell characteristic score (ICCS) model was constructed by using multivariate Cox regression analysis. Results: The immune cell infiltration patterns across 32 cancer types were identified, and patients in the high immune cell infiltration cluster had worse overall survival (OS) but better progression-free interval (PFI) compared to the low immune cell infiltration cluster. However, immune cell infiltration showed inconsistent prognostic value depending on the cancer type. High immune cell infiltration (High CI) indicated a worse prognosis in brain lower grade glioma (LGG), glioblastoma multiforme (GBM), and uveal melanoma (UVM), and favorable prognosis in adrenocortical carcinoma (ACC), cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC), cholangiocarcinoma (CHOL), head and neck squamous cell carcinoma (HNSC), liver hepatocellular carcinoma (LIHC), lung adenocarcinoma (LUAD), sarcoma (SARC), and skin cutaneous melanoma (SKCM). LUAD prognosis was significantly influenced by the infiltration of 13 immune cell types, with high infiltration of all but Type 2 T helper (Th2) cells correlating with a favorable prognosis. The ICCS model based on six most survival-relevant immune cell populations was generated that classified patients into low- and high-ICCS groups with good and poor prognoses, respectively. The multivariate and stratified analyses further revealed that the ICCS was an independent prognostic factor for LUAD. Conclusions: The infiltration of immune cells in 32 cancer types was quantified, and considerable heterogeneity was observed in the prognostic relevance of these cells in different cancer types. An ICCS model was constructed for LUAD with competent prognostic performance, which can further deepen our understanding of the TME of LUAD and can have implications for immunotherapy.

The E3 ubiquitin ligase adaptor speckle-type POZ protein (SPOP) is frequently dysregulated in prostate adenocarcinoma (PC), via either somatic mutations or mRNA downregulation, suggesting an important tumor suppressor function. To examine its physiologic role in the prostate epithelium in vivo, we generated mice with prostate-specific biallelic ablation of Spop. These mice exhibited increased prostate mass, prostate epithelial cell proliferation, and expression of c-MYC protein compared to littermate controls, and eventually developed prostatic intraepithelial neoplasia (PIN). We found that SPOPWT can physically interact with c-MYC protein and, upon exogenous expression in vitro, can promote c-MYC ubiquitination and degradation. This effect was attenuated in PC cells by introducing PC-associated SPOP mutants or upon knockdown of SPOP via short-hairpin-RNA, suggesting that SPOP inactivation directly increases c-MYC protein levels. Gene set enrichment analysis revealed enrichment of Myc-induced genes in transcriptomic signatures associated with SPOPMT. Likewise, we observed strong inverse correlation between c-MYC activity and SPOP mRNA levels in two independent PC patient cohorts. The core SPOPMT;MYCHigh transcriptomic response, defined by the overlap between the SPOPMT and c-MYC transcriptomic programs, was also associated with inferior clinical outcome in human PCs. Finally, the organoid-forming capacity of Spop-null murine prostate cells was more sensitive to c-MYC inhibition than that of Spop-WT cells, suggesting that c-MYC upregulation functionally contributes to the proliferative phenotype of Spop knock-out prostates. Taken together, our data highlight SPOP as an important regulator of luminal epithelial cell proliferation and c-MYC expression in prostate physiology, identify c-MYC as a novel bona fide SPOP substrate, and help explain the frequent inactivation of SPOP in human PC. We propose SPOPMT–induced stabilization of c-MYC protein as a novel mechanism that can increase total c-MYC levels in PC cells, in addition to amplification of c-MYC locus.

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