Signal Sequence Receptor 2 is required for survival of human melanoma cells as part of an unfolded protein response to endoplasmic reticulum stress

Endoplasmic Reticulum Stress-Related Signature for Predicting Prognosis and Immune Features in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) with cancer cells under endoplasmic reticulum (ER) stress has a poor prognosis. This study is aimed at discovering credible biomarkers for predicting the prognosis of HCC based on ER stress-related genes (ERSRGs). We constructed a novel four-ERSRG prognostic risk model, including PON1, AGR2, SSR2, and TMCC1, through a series of bioinformatic approaches, which can accurately predict survival outcomes in HCC patients. Higher risk scores were linked to later grade, recurrence, advanced TNM stage, later T stage, and HBV infection. In addition, 20 fresh frozen tumors and normal tissues from HCC patients were collected and used to validate the genes expressed in the signature by qRT-PCR and immunohistochemical (IHC) assays. Moreover, we found the ER stress-related signature could reflect the infiltration levels of different immune cells in the tumor microenvironment (TME) and forecast the efficacy of immune checkpoint inhibitor (ICI) treatment. Finally, we created a nomogram incorporating this ER stress-related signature. In conclusion, our constructed four-gene risk model associated with ER stress can accurately predict survival outcomes in HCC patients, and the model's risk score is associated with the poor clinical classification.

Overexpression of SSR2 promotes proliferation of liver cancer cells and predicts prognosis of patients with hepatocellular carcinoma

Signal Sequence Receptor Subunit 2 (SSR2) is a key endoplasmic reticulum gene involved in protein folding and processing. Previous studies found that it was upregulated in several cancers, but its precise role in hepatocellular carcinoma (HCC) remains unclear. To have a better understanding of this gene in HCC, we examined the expression of SSR2 in HCC tissues by analysing The Cancer Genome Atlas (TCGA) data and immunohistochemistry. We also assessed the association between SSR2 expression and clinicopathological characteristics of HCC patients and patient survival. Potential function of SSR2 was predicted through GSEA and protein–protein interaction analysis. MTT, flowcytometry, transwell and a nude mice xenograft model were employed to investigate the biological functions in vivo and in vitro. The results showed that the expression of SSR2 was significantly increased in HCC tissues, and SSR2 expression was associated with several clinical characteristics. In addition, patients with higher SSR2 expression had poorer survival. Enrichment analysis suggested that SSR2 was probably involved in biological process or signalling pathways related to G2/M checkpoint, passive transmembrane transporter activity, ATF2_S_UP. V1_UP and ncRNA metabolic process. Further experimental study showed that SSR2 knockdown inhibited cell proliferation, migration and invasion ability and promoted apoptosis and cell cycle arrest in vitro. Moreover, downregulation of SSR2 also repressed the growth of HepG2 cells in vivo. In conclusion, our study suggests that SSR2 may act as an oncogene in HCC.

Clinical Value for Diagnosis and Prognosis of Signal Sequence Receptor 1 (SSR1) and Its Potential Mechanism in Hepatocellular Carcinoma: A Comprehensive Study Based on High-Throughput Data Analysis

Objective

Hepatocellular Carcinoma (HCC) has the characteristics of high incidence and poor prognosis. However, the underlying mechanism of HCC has not yet been fully elucidated. This study aims to investigate the potential mechanism and clinical significance of signal sequence receptor (SSR1) in HCC through bioinformatics methods.

Methods

Four online (GEPIA, TIMER, TCGA, and GEO) databases were used to explore the expression level of SSR1 in HCC. The summary receiver operating characteristic (SROC) analysis and standardized mean difference (SMD) calculation were performed further to detect its diagnostic ability and expression level. The Human Protein Atlas (HPA) database was applied to verify the level of SSR1 protein expression. Chi-square test and Fisher’s exact test were carried out to determine the clinical relevance of SSR1 expression. KM survival analysis, univariate and multivariate COX regression analyses were employed to explore the prognostic impact of SSR1. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene set enrichment analysis (GSEA) were implemented to reveal the underlying mechanism of SSR1. Quantitative Real-Time Polymerase Chain Reaction (QRT-PCR) was used to verify the expression of SSR1 in HCC.

Results

SSR1 was significantly overexpressed in HCC (SMD=1.25, P=0.03) and had the moderate diagnostic ability (AUC=0.84). SSR1 expression was significantly correlated with T stage, Gender, Pathologic stage (All P<0.05). Patients with high SSR1 expression had shorter overall survival (OS). Univariate and multivariate Cox regression analyses showed that high SSR1 expression was an independent risk factor for poor prognosis. KEGG analysis showed that SSR1-related genes were enriched in the cell cycle, DNA replication, and TGF-beta signaling pathway. GSEA analysis also shows that the high expression of SSR1 is related to the activation of the above three signal pathways. qRT-PCR showed that the SSR1 expression in HCC was significantly higher than the Peri-carcinoma tissue (PHCC) and the corresponding normal liver tissue.

Conclusion

SSR1 expression was significantly up-regulated, and it had the potential as a biomarker for the diagnosis and prognosis of HCC. It was very likely to participate in the occurrence and development of HCC by regulating the cell cycle. In summary, our study comprehensively analyzed the clinical value of SSR1 and also conducted a preliminary study on its potential mechanism, which will provide inspiration for the in-depth study of SSR1 in HCC.

The integrated stress response mediates necrosis in murine Mycobacterium tuberculosis granulomas

The mechanism by which only some individuals infected with Mycobacterium tuberculosis develop necrotic granulomas with progressive disease while others form controlled granulomas that contain the infection remains poorly defined. Mice carrying the sst1-suscepible (sst1S) genotype develop necrotic inflammatory lung lesions, similar to human tuberculosis (TB) granulomas, which are linked to macrophage dysfunction, while their congenic counterpart (B6) mice do not. In this study we report that (a) sst1S macrophages developed aberrant, biphasic responses to TNF characterized by superinduction of stress and type I interferon pathways after prolonged TNF stimulation; (b) the late-stage TNF response was driven via a JNK/IFN-β/protein kinase R (PKR) circuit; and (c) induced the integrated stress response (ISR) via PKR-mediated eIF2α phosphorylation and the subsequent hyperinduction of ATF3 and ISR-target genes Chac1, Trib3, and Ddit4. The administration of ISRIB, a small-molecule inhibitor of the ISR, blocked the development of necrosis in lung granulomas of M. tuberculosis-infected sst1S mice and concomitantly reduced the bacterial burden. Hence, induction of the ISR and the locked-in state of escalating stress driven by the type I IFN pathway in sst1S macrophages play a causal role in the development of necrosis in TB granulomas. Interruption of the aberrant stress response with inhibitors such as ISRIB may offer novel host-directed therapy strategies.

Integrated Proteomic and Glycoproteomic Characterization of Human High-Grade Serous Ovarian Carcinoma

Many gene products exhibit great structural heterogeneity because of an array of modifications. These modifications are not directly encoded in the genomic template but often affect the functionality of proteins. Protein glycosylation plays a vital role in proper protein functions. However, the analysis of glycoproteins has been challenging compared with other protein modifications, such as phosphorylation. Here, we perform an integrated proteomic and glycoproteomic analysis of 83 prospectively collected high-grade serous ovarian carcinoma (HGSC) and 23 non-tumor tissues. Integration of the expression data from global proteomics and glycoproteomics reveals tumor-specific glycosylation, uncovers different glycosylation associated with three tumor clusters, and identifies glycosylation enzymes that were correlated with the altered glycosylation. In addition to providing a valuable resource, these results provide insights into the potential roles of glycosylation in the pathogenesis of HGSC, with the possibility of distinguishing pathological outcomes of ovarian tumors from non-tumors, as well as classifying tumor clusters.

Ubiquitin ligases and medulloblastoma: genetic markers of the four consensus subgroups identified through transcriptome datasets

The ubiquitin proteasome system regulates key cellular processes in normal and in cancer cells. Herein, we review published data on the role of ubiquitin ligases in the four major subgroups of medulloblastoma (MB). While conventional literature serves as an initial source of information on cellular pathways in MB, large publicly available datasets of gene expression can be used to add information not previously identified in the literature. By analysing the publicly available Cavalli dataset, we show that increased expression of ZNRF3 characterizes the WNT subgroup of MB. The ZNRF3 gene codes for an E3 ligase associated with WNT receptors. Loss of a copy of chromosome 6 in a subtype of the WNT group was associated with decreased expression of the gene encoding the E3 ligase RNF146. While the E3 ligase SMURF regulates SHH receptors, increased expression of the gene encoding the Cullin Ring E3 adaptor PPP2R2C was statistically a better genetic marker of the SHH group. Genes whose expression was statistically strongly related to Group 3 included the E3 ligase gene TRIM58, and the gene for the E3 ligase adaptor, PPP2R2B. Group 4 MB was associated with expression of genes encoding several E3 ligases and E3 ligase adaptors involved in ribosome biogenesis. Increased expression of the genes encoding the E3 ligase adaptors and transcription repressors ZBTB18 and ZBTB38 were also noted in subgroup 4. These data suggest that several E3 ligases and their adaptors should be investigated as therapeutic targets for subgroup specific MB brain tumors.

SSR2 overexpression associates with tumorigenesis and metastasis of Hepatocellular Carcinoma through modulating EMT

Background: Hepatocellular carcinoma (HCC) is a common malignancy around the world. The molecular mechanisms underlying HCC tumorigenesis and metastasis are far from clear. Numerous studies have pointed out that signal sequence receptor (SSR) is an endoplasmic reticulum-related protein involved in protein folding and processing of eukaryotic cells. SSR2 is a subunit of SSR protein, but the role of SSR2 in hepatocellular carcinoma is largely unknown and warrants further study.

Materials and Methods: Several public databases were data mined to analyze the expression of four subunits of SSR between tumor and its peritumor counterparts. Also, the expression of SSR2 in our own collected tissues from HCC patients were analyzed by IHC and quantitative PCR. Survival analyses were conducted to delineate the prognostic value of SSR2. Clinical data were obtained followed by analysis based on SSR2 expression. Afterwards, cell proliferation, migration and invasion were detected by IncuCyte and trans-well assays, respectively. RNA interference was carried out by transfecting specific siRNA targeting SSR2 into cells using lipo2000. Western blot was applied to validate the knockdown effect and regulation on EMT-related proteins.

Results: We examined the expression of SSR and its correlation with recurrence and survival of patients. We discovered that SSR2 overexpression was negatively associated with survival of HCC patients from TCGA databases and the mutation of SSR2 was most among the four subunits of SSR protein. Additionally, in this study, we collected tumor and adjacent tissues from 125 cases of HCC patients. Through constructing tissue microarray, we have identified that SSR2 was highly expressed in HCC tumor tissues compared with adjacent normal tissues of hepatocellular carcinoma patients by immunohistochemistry assays. Furthermore, Kaplan-Meier survival analysis from our collected tissues revealed that the overexpression of SSR2 was inversely correlated with disease free survival and overall survival of HCC patients. We elucidated that SSR2 promotes proliferation, migration and invasion of HCC cells. SSR2 knockdown suppressed epithelial mesenchymal transition (EMT) of HCC cells.

Conclusions: These results collectively show that SSR2 is overexpressed in HCC tumor tissues, and it is an important factor in predicting survival of HCC patients. Additionally, it is involved in metastasis of HCC. These findings may help to exploit SSR2 as a novel factor in predicting prognosis and metastasis of HCC.

The metabolic syndrome alters the miRNA signature of porcine adipose tissue-derived mesenchymal stem cells

Autologous transplantation of mesenchymal stem cells (MSCs) is a viable option for the treatment of several diseases. Evidence indicates that MSCs release extracellular vesicles (EVs) and that EVs shuttle miRNAs to damaged parenchymal cells to activate an endogenous repair program. We hypothesize that comorbidities may interfere with the packaging of cargo in MSC-derived EVs. Therefore, we examined whether metabolic syndrome (MetS) modulates the miRNA content packed within MSC-derived EVs. MSCs were collected from swine abdominal adipose tissue after 16 weeks of lean or obese diet (n = 7 each). Next-generation RNA sequencing of miRNAs (miRNA-seq) was performed to identify miRNAs enriched in MSC-derived EVs and their predicted target genes. Functional pathway analysis of the top 50 target genes of the top 4 miRNAs enriched in each group was performed using gene ontology analysis. Lean- and MetS-EVs were enriched in, respectively, 14 and 8 distinct miRNAs. Target genes of miRNAs enriched in MetS-EVs were implicated in the development of MetS and its complications, including diabetes-related pathways, validated transcriptional targets of AP1 family members Fra1 and Fra2, Class A/1 (Rhodopsin-like receptors), and Peptide ligand-binding receptors. In contrast, miRNAs enriched in Lean EVs target primarily EphrinA-EPHA and the Rho family of GTPases. MetS alters the miRNA content of EVs derived from porcine adipose tissue MSCs. These alterations could impair the efficacy and limit the therapeutic use of autologous MSCs in subjects with MetS. Our findings may assist in developing adequate regenerative strategies to preserve the reparative potency of MSCs in individuals with MetS. © 2017 International Society for Advancement of Cytometry.