No abstract

The immunoproteasome plays a key role in generation of HLA peptides for T cell-mediated immunity. Integrative genomic and proteomic analysis of non-small cell lung carcinoma (NSCLC) cell lines revealed significantly reduced expression of immunoproteasome components and their regulators associated with epithelial to mesenchymal transition. Low expression of immunoproteasome subunits in early stage NSCLC patients was associated with recurrence and metastasis. Depleted repertoire of HLA class I-bound peptides in mesenchymal cells deficient in immunoproteasome components was restored with either IFNγ or 5-aza-2′-deoxycytidine (5-aza-dC) treatment. Our findings point to a mechanism of immune evasion of cells with a mesenchymal phenotype and suggest a strategy to overcome immune evasion through induction of the immunoproteasome to increase the cellular repertoire of HLA class I-bound peptides.

Purpose Lung cancer stem cells (CSCs) with elevated aldehyde dehydrogenase (ALDH) activity are self-renewing, clonogenic and tumorigenic. The purpose of our study is to elucidate the mechanisms by which lung CSCs are regulated. Experimental Design A genome-wide gene expression analysis was performed to identify genes differentially expressed in the ALDH+ vs. ALDH− cells. RT-PCR, western blot and Aldefluor assay were used to validate identified genes. To explore the function in CSCs we manipulated their expression followed by colony and tumor formation assays. Results We identified a subset of genes that were differentially expressed in common in ALDH+ cells, among which ALDH1A3 was the most upregulated gene in ALDH+ vs. ALDH− cells. ShRNA-mediated knockdown of ALDH1A3 in NSCLCs resulted in a dramatic reduction in ALDH activity, clonogenicity and tumorigenicity, indicating that ALDH1A3 is required for tumorigenic properties. By contrast, overexpression of ALDH1A3 by itself it was not sufficient to increase tumorigenicity. The ALDH+ cells also expressed more activated Signal Transducers and Activators of Transcription 3 (STAT3) than ALDH− cells. Inhibition of STAT3 or its activator EZH2 genetically or pharmacologically diminished the level of ALDH+ cells and clonogenicity. Unexpectedly, ALDH1A3 was highly expressed in female, never smokers, well differentiated tumors, or adenocarcinoma. ALDH1A3 low expression was associated with poor overall survival. Conclusion Our data show that ALDH1A3 is the predominant ALDH isozyme responsible for ALDH activity and tumorigenicity in most NSCLCs, and that inhibiting either ALDH1A3 or the STAT3 pathway are potential therapeutic strategies to eliminate the ALDH+ subpopulation in NSCLCs.

Advanced prostate adenocarcinomas enriched in stem-cell features, as well as variant androgen receptor (AR)-negative neuroendocrine (NE)/small-cell prostate cancers are difficult to treat, and account for up to 30% of prostate cancer-related deaths every year. While existing therapies for prostate cancer such as androgen deprivation therapy (ADT), destroy the bulk of the AR-positive cells within the tumor, eradicating this population eventually leads to castration-resistance, owing to the continued survival of AR-/lo stem-like cells. In this study, we identified a critical nexus between p38MAPK signaling, and the transcription factor Forkhead Box Protein C2 (FOXC2) known to promote cancer stem-cells and metastasis. We demonstrate that prostate cancer cells that are insensitive to ADT, as well as high-grade/NE prostate tumors, are characterized by elevated FOXC2, and that targeting FOXC2 using a well-tolerated p38 inhibitor restores epithelial attributes and ADT-sensitivity, and reduces the shedding of circulating tumor cells in vivo with significant shrinkage in the tumor mass. This study thus specifies a tangible mechanism to target the AR-/lo population of prostate cancer cells with stem-cell properties.

BRG1, a core component of the SWI/SNF chromatin-remodeling complex, has been implicated in cancer development; however, the biological significance of BRG1 in breast cancer remains unknown. We explored the role of BRG1 in human breast cancer pathogenesis. Using tissue microarray and immunohistochemistry, we evaluated BRG1 staining in 437 breast cancer specimens and investigated its role in breast cancer cell proliferation, migration and invasion. Our Kaplan-Meier survival curves showed that high BRG1 expression is inversely correlated with both overall (P = 0.000) and disease-specific (P = 0.000) 5-year patient survival. Furthermore, we found that knockdown of BRG1 by RNA interference markedly inhibits cell proliferation and causes cessation of cell cycle. This reduced cell proliferation is due to G1 phase arrest as cyclin D1 and cyclin E are diminished whereas p27 is upregulated. Moreover, BRG1 depletion induces the expression of TIMP-2 but reduces MMP-2, thereby inhibiting the ability of cells to migrate and to invade. These results highlight the importance of BRG1 in breast cancer pathogenesis and BRG1 may serve as a prognostic marker as well as a potentially selective therapeutic target.

Primary effusion lymphoma (PEL) is a rare type of large B-cell lymphoma associated with human herpesvirus 8 (HHV8) infection. Patients with PEL usually present with an effusion, but occasionally with an extracavitary mass. In this study, we reported a cohort of 70 patients with PEL: 67 men and 3 women with a median age of 46 years (range 26–91). Of these, 56 (80%) patients had human immunodeficiency virus (HIV) infection, eight were HIV-negative, and six had unknown HIV status. Nineteen (27%) patients had Kaposi sarcoma. Thirty-five (50%) patients presented with effusion only, 27 (39%) had an extracavitary mass or masses only, and eight (11%) had both effusion and extracavitary disease. The lymphoma cells showed plasmablastic, immunoblastic, or anaplastic morphology. All 70 (100%) cases were positive for HHV8. Compared with effusion-only PEL, patients with extracavitary-only PEL were younger (median age, 42 vs 52 years, p = 0.001), more likely to be HIV-positive (88.9% vs 68.6%, p = 0.06) and EBV-positive (76.9% vs 51.9%, p = 0.06), and less often positive for CD45 (69.2% vs 96.2%, p = 0.01), EMA (26.7% vs 100%, p = 0.0005), and CD30 (60% vs 81.5%, p = 0.09). Of 52 (50%) patients with clinical follow-up, 26 died after a median follow-up time of 40.0 months (range 0–96), and the median overall survival was 42.5 months. The median OS for patients with effusion-only and with extracavitary-only PEL were 30.0 and 37.9 months, respectively (p = 0.34), and patients with extracavitary-only PEL had a lower mortality rate at the time of last follow-up (35% vs 61.5%, p = 0.07). The median OS for HIV-positive and HIV-negative patients were 42.5 and 6.8 months, respectively (p = 0.57), and they had a similar mortality rate of 50% at last follow-up. In conclusion, patients presenting with effusion-only versus extracavitary-only disease are associated with different clinicopathologic features. PEL is an aggressive lymphoma with a poor prognosis, regardless of extracavitary presentation or HIV status.

The RNA polypyrimidine tract-binding protein PTBP3 is a little studied paralog of PTBP1, which has oncogenic properties. In this study, we demonstrate that PTBP3 induces epithelial-mesenchymal transition (EMT) in breast tumor cells and promotes their invasive growth and metastasis. Elevated expression of PTBP3 associated significantly with lymph node metastasis, advanced histology grade, TNM stage, and poor 5-year overall survival of patients. In human mammary epithelial cells, PTBP3 overexpression was sufficient to induce EMT and to enhance cell migration, invasion, and cancer stem-like cell properties. PTBP3 regulated expression of the EMT regulatory transcription factor ZEB1 by binding the 3'UTR of its mRNA, thereby preventing its degradation. Conversely, ZEB1 ablation blocked the ability of PTBP3 to induce EMT. Overall, our findings define PTBP3 as a regulator of EMT that acts by governing expression of ZEB1, and they establish an oncogenic function of PTBP3, suggesting its candidacy as a theranostic target. These findings define PTBP3 as a regulator of EMT that acts by governing expression of ZEB1, and they establish an oncogenic function of PTBP3, suggesting its candidacy as a theranostic target. .

The shear stress-shear rate relationship of six food thickeners from guar gum, modified starch and xanthan gum in homogenised and pasteurised full cream (HPFC), skim milk (SKIM) and ultra-high temperature or ultra-heat treated full cream (UHT) was investigated at 20°C. For all the thickened fluids, shear stress increased as the rate of shear increased from 1 to 100 s À1 . An increase in solids content increased the viscosity, density and yield stress. The type of milk significantly influenced (p < 0.05) the density of the fluids and SKIM milk could yield the densest fluids. Irrespective of the type of milk, the guar gum-based thickened fluids (Guarcol TM and Supercol TM ) were the most viscous, and they exhibited the highest yield stress. Among the three types of milk, the most viscous thickened fluids or thickened fluids with the highest yield stress were obtained when SKIM was the dispersing medium. The Herschel-Bulkley models were found to be the most suitable rheological models for the shear stress-shear rate data. The regression parameters obtained are valuable in calculating the weights of the thickener and dispersing medium for clinical uses. Crown