Downregulation of the N-myc downstream regulated gene 1 is related to enhanced proliferation, invasion and migration of pancreatic cancer

Multifaceted and Intricate Oncogenic Mechanisms of NDRG1 in Head and Neck Cancer Depend on Its C-Terminal 3R-Motif

N-Myc downstream-regulated 1 (NDRG1) has inconsistent oncogenic functions in various cancers. We surveyed and characterized the role of NDRG1 in head and neck cancer (HNC). Cellular methods included spheroid cell formation, clonogenic survival, cell viability, and Matrigel invasion assays. Molecular techniques included transcriptomic profiling, RT-qPCR, immunoblotting, in vitro phosphorylation, immunofluorescent staining, and confocal microscopy. Prognostic significance was assessed by Kaplan–Meier analysis. NDRG1 participated in diverse oncogenic functions in HNC cells, mainly stress response and cell motility. Notably, NDRG1 contributed to spheroid cell growth, radio-chemoresistance, and upregulation of stemness-related markers (CD44 and Twist1). NDRG1 facilitated cell migration and invasion, and was associated with modulation of the extracellular matrix molecules (fibronectin, vimentin). Characterizing the 3R-motif in NDRG1 revealed its mechanism in the differential regulation of the phenotypes. The 3R-motif displayed minimal effect on cancer stemness but was crucial for cell motility. Phosphorylating the motif by GSK3b at serine residues led to its nuclear translocation to promote motility. Clinical analyses supported the oncogenic function of NDRG1, which was overexpressed in HNC and associated with poor prognosis. The data elucidate the multifaceted and intricate mechanisms of NDRG1 in HNC. NDRG1 may be a prognostic indicator or therapeutic target for refractory HNC.

The role of autophagy in pancreatic cancer progression

Patients with pancreatic cancer have an abysmal survival rate. The poor prognosis of pancreatic cancer is due to the difficulty of making an early diagnosis, high rate of metastasis, and frequent chemoresistance. In recent years, as a self-regulatory procedure within cells, the effect and mechanism of autophagy have been explored. Dysregulated autophagy serves as a double-edged sword in cancer development in which autophagy inhibits cancer initiation but promotes cancer progression. After tumor formation, activation of autophagy can induce epithelial-mesenchymal transition, regulate metabolism, specifically glutamine usage and the glycolytic process, and mediate drug resistance in pancreatic cancer. Multiple genes, RNA molecules, proteins, and certain drugs exert antitumor effects by inhibiting autophagy-mediated drug resistance. Several clinical trials have combined autophagy inhibitors with chemotherapeutic drugs in pancreatic cancer treatment, some of which have shown promising results. In conclusion, autophagy plays a vital role in pancreatic cancer progression and deserves further study.

Molecular Interplays Between Cell Invasion and Radioresistance That Lead to Poor Prognosis in Head-Neck Cancer

Background

Cancer metastasis and recurrence after radiotherapy are the significant causes of poor prognosis in head-neck cancer (HNC). Clinically, it is commonly found that patients with either condition may accompany the outcome of the other. We hypothesized that HNC cells might exhibit a cross-phenotypic attribute between cell invasion and radioresistance. To discover effective biomarkers for the intervention of aggressive cancer at one time, the potential molecules that interplay between these two phenotypes were investigated.

Materials and Methods

Three isogenic HNC cell sublines with high invasion or radioresistance properties were established. Transcriptomic and bioinformatic methods were used to globally assess the phenotypic-specific genes, functional pathways, and co-regulatory hub molecules. The associations of gene expressions with patient survival were analyzed by Kaplan-Meier plotter, a web-based tool, using the HNSCC dataset (n=500). The molecular and cellular techniques, including RT-qPCR, flow cytometry, cell invasion assay, and clonogenic survival assay, were applied.

Results

The phenotypic crosstalk between cell invasion and radioresistance was validated, as shown by the existence of mutual properties in each HNC subline. A total of 695 genes was identified in associations with these two phenotypes, including 349 upregulated and 346 downregulated in HNC cells. The focal adhesion mechanism showed the most significant pathway to co-regulate these functions. In the analysis of 20 up-regulatory genes, a general portrait of correlative expression was found between these phenotypic cells (r=0.513, p=0.021), and nine molecules exhibited significant associations with poor prognosis in HNC patients (HR>1, p<0.050). Three hub genes were identified (ITGA6, TGFB1, and NDRG1) that represented a signature of interplayed molecules contributing to cell invasion, radioresistance and leading to poor prognosis. The ITGA6 was demonstrated as a prominent biomarker. The expression of ITGA6 correlated with the levels of several extracellular and apoptotic/anti-apoptotic molecules. Functionally, silencing ITGA6 suppressed cell migration, invasion, and attenuated radioresistance in HNC cells.

Conclusions

A panel of interplay molecules was identified that contribute to cell invasion and radioresistance, leading to poor prognosis. These panel molecules, such as ITGA6, may serve as predictive markers of radioresistance, prognostic markers of metastasis, and molecular therapeutic targets for refractory HNC.

Impact of DNA repair and reactive oxygen species levels on radioresistance in pancreatic cancer

PURPOSE

Radioresistance in pancreatic cancer patients remains a critical obstacle to overcome. Understanding the molecular mechanisms underlying radioresistance may achieve better response to radiotherapy and thereby improving the poor treatment outcome. The aim of the present study was to elucidate the mechanisms leading to radioresistance by detailed characterization of isogenic radioresistant and radiosensitive cell lines.

METHODS

The human pancreatic cancer cell lines, Panc-1 and MIA PaCa-2 were repeatedly exposed to radiation to generate radioresistant (RR) isogenic cell lines. The surviving cells were expanded, and their radiosensitivity was measured using colony formation assay. Tumor growth delay after irradiation was determined in a mouse pancreatic cancer xenograft model. Gene and protein expression were analyzed using RNA sequencing and Western blot, respectively. Cell cycle distribution and apoptosis (Caspase 3/7) were measured by FACS analysis. Reactive oxygen species generation and DNA damage were analyzed by detection of CM-H₂DCFDA and γH2AX staining, respectively. Transwell chamber assays were used to investigate cell migration and invasion.

RESULTS

The acquired radioresistance of RR cell lines was demonstrated in vitro and validated in vivo. Ingenuity pathway analysis of RNA sequencing data predicted activation of cell viability in both RR cell lines. RR cancer cell lines demonstrated greater DNA repair efficiency and lower basal and radiation-induced reactive oxygen species levels. Migration and invasion were differentially affected in RR cell lines.

CONCLUSIONS

Our data indicate that repeated exposure to irradiation increases the expression of genes involved in cell viability and thereby leads to radioresistance. Mechanistically, increased DNA repair capacity and reduced oxidative stress might contribute to the radioresistant phenotype.

Cx43 phosphorylation sites regulate pancreatic cancer metastasis

Pancreatic ductal adenocarcinoma (PDA) is aggressive, highly metastatic and characterized by a robust desmoplasia. Connexin proteins that form gap junctions have been implicated in tumor suppression for over 30 years. Cx43, the most widely expressed connexin, regulates cell behaviors, including migration and proliferation. Thus, we hypothesized that Cx43 could regulate PDA progression. Phosphorylation of Cx43 by Casein Kinase 1 (CK1) regulates gap junction assembly. We interbred the well-established Kras^{LSL-G12D/+;p48Cre/+} (KC) mouse model of PDA with homozygous "knock-in" mutant Cx43 mice bearing amino acid substitution at CK1 sites (Cx43^CK1A) and found profound and surprising effects on cancer progression. Crossing the Cx43^CK1A mouse onto the KC background (termed KC;Cx^CK1A) led to significant extension of lifespan, from a median of 370 to 486 days (p = 0.03) and a decreased incidence of metastasis (p = 0.045). However, when we examined early stages of disease, we found more rapid onset of tissue remodeling in the KC;Cx^CK1A mouse followed by divergence to a cystic phenotype. During tumorigenesis, gap junctions are increasingly present in stromal cells of the KC mice but are absent from the KC;Cx43^CK1A mice. Tail vein metastasis assays with cells derived from KC or KC;Cx^CK1A tumors showed that KC;Cx^CK1A cells could efficiently colonize the lung and downregulate Cx43 expression, arguing that inhibition of metastasis was not occurring at the distal site. Instead, stromal gap junctions, their associated signaling events or other unknown Cx43-dependent events facilitate metastatic capacity in the primary tumor.

Machine Learning for Building Immune Genetic Model in Hepatocellular Carcinoma Patients

BACKGROUND

Hepatocellular carcinoma (HCC) is the leading liver cancer with special immune microenvironment, which played vital roles in tumor relapse and poor drug responses. In this study, we aimed to explore the prognostic immune signatures in HCC and tried to construct an immune-risk model for patient evaluation.

METHODS

RNA sequencing profiles of HCC patients were collected from the cancer genome Atlas (TCGA), international cancer genome consortium (ICGC), and gene expression omnibus (GEO) databases (GSE14520). Differentially expressed immune genes, derived from ImmPort database and MSigDB signaling pathway lists, between tumor and normal tissues were analyzed with Limma package in R environment. Univariate Cox regression was performed to find survival-related immune genes in TCGA dataset, and in further random forest algorithm analysis, significantly changed immune genes were used to generate a multivariate Cox model to calculate the corresponding immune-risk score. The model was examined in the other two datasets with recipient operation curve (ROC) and survival analysis. Risk effects of immune-risk score and clinical characteristics of patients were individually evaluated, and significant factors were then used to generate a nomogram.

RESULTS

There were 52 downregulated and 259 upregulated immune genes between tumor and relatively normal tissues, and the final immune-risk model (based on SPP1, BRD8, NDRG1, KITLG, HSPA4, TRAF3, ITGAV and MAP4K2) can better differentiate patients into high and low immune-risk subpopulations, in which high score patients showed worse outcomes after resection (p < 0.05). The differentially enriched pathways between the two groups were mainly about cell proliferation and cytokine production, and calculated immune-risk score was also highly correlated with immune infiltration levels. The nomogram, constructed with immune-risk score and tumor stages, showed high accuracy and clinical benefits in prediction of 1-, 3- and 5-year overall survival, which is useful in clinical practice.

CONCLUSION

The immune-risk model, based on expression of SPP1, BRD8, NDRG1, KITLG, HSPA4, TRAF3, ITGAV, and MAP4K2, can better differentiate patients into high and low immune-risk groups. Combined nomogram, using immune-risk score and tumor stages, could make accurate prediction of 1-, 3- and 5-year survival in HCC patients.

NDRG1 suppresses basal and hypoxia-induced autophagy at both the initiation and degradation stages and sensitizes pancreatic cancer cells to lysosomal membrane permeabilization

BACKGROUND

N-myc downstream regulated gene 1 (NDRG1) is an established stress-response protein. This study investigated the effects of NDRG1 on autophagic degradation and how this can be therapeutically exploited.

METHODS

Cell culture, western analysis, confocal microscopy, acridine orange staining, cholesterol determination, cellular proliferation assessment and combination index (CI) estimation.

RESULTS

NDRG1 expression suppressed autophagic degradation and autolysosome formation, measured by increased p62 expression and reduced co-localization between the well-characterized, autophagosomal and lysosomal markers, LC3 and LAMP2, respectively. NDRG1 elicited autophagic suppression at the initiation stage of autophagy. The NDRG1-inducer and anti-cancer agent, di-2-pyridylketone 4,4,-dimethyl-3-thiosemicarbazone (Dp44mT), was able to induce lysosomal membrane permeabilization (LMP). Over-expression of NDRG1 further sensitized cells to LMP mediated by both Dp44mT, or the redox active Dp44mT‑copper complex. This sensitization may be mediated via a decrease in cholesterol levels upon NDRG1 expression, as cholesterol stabilizes lysosomal membranes. However, the effect of NDRG1 on cholesterol appeared independent of the key energy homeostasis sensor, 5' AMP-activated protein kinase (AMPK), whose activation was significantly (p < 0.001) reduced by NDRG1. Finally, Dp44mT synergistically potentiated the anti-proliferative activity of Gemcitabine that activates autophagy. In fact, Dp44mT and Gemcitabine (Combination Index (CI): 0.38 ± 0.07) demonstrated higher synergism versus the autophagy inhibitor, Bafilomycin A1 and Gemcitabine (CI: 0.64 ± 0.19).

CONCLUSIONS AND GENERAL SIGNIFICANCE

Collectively, this study demonstrated a dual-inhibitory mechanism of NDRG1 on autophagic activity, and that NDRG1 expression sensitized cells to Dp44mT-induced LMP. Considering the ability of Dp44mT to inhibit autophagy, studies demonstrated the potential of combination therapy for cancer treatment of Dp44mT with Gemcitabine.

Integrative analysis of common genes and driver mutations implicated in hormone stimulation for four cancers in women

Cancer is one of the leading cause of death of women worldwide, and breast, ovarian, endometrial and cervical cancers contribute significantly to this every year. Developing early genetic-based diagnostic tools may be an effective approach to increase the chances of survival and provide more treatment opportunities. However, the current cancer genetic studies are mainly conducted independently and, hence lack of common driver genes involved in cancers in women. To explore the potential common molecular mechanism, we integrated four comprehensive literature-based databases to explore the shared implicated genetic effects. Using a total of 460 endometrial, 2,068 ovarian, 2,308 breast and 537 cervical cancer-implicated genes, we identified 52 genes which are common in all four types of cancers in women. Furthermore, we defined their potential functional role in endogenous hormonal regulation pathways within the context of four cancers in women. For example, these genes are strongly associated with hormonal stimulation, which may facilitate rapid diagnosis and treatment management decision making. Additional mutational analyses on combined the cancer genome atlas datasets consisting of 5,919 gynaecological and breast tumor samples were conducted to identify the frequently mutated genes across cancer types. For those common implicated genes for hormonal stimulants, we found that three quarter of 5,919 samples had genomic alteration with the highest frequency in MYC (22%), followed by NDRG1 (19%), ERBB2 (14%), PTEN (13%), PTGS2 (13%) and CDH1 (11%). We also identified 38 hormone related genes, eight of which are associated with the ovulation cycle. Further systems biology approach of the shared genes identified 20 novel genes, of which 12 were involved in the hormone regulation in these four cancers in women. Identification of common driver genes for hormone stimulation provided an unique angle of involving the potential of the hormone stimulants-related genes for cancer diagnosis and prognosis.

Upregulation of NDRG1 predicts poor outcome and facilitates disease progression by influencing the EMT process in bladder cancer

N-myc downstream regulated gene 1 (NDRG1) is an intracellular protein involved in cell differentiation and was recently reported to exert various effects in several cancers. However, its expression and role in bladder cancer remain unclear. Our study enrolled 100 bladder cancer patients to detect NDRG1 expression in tumour tissues by immunohistochemistry. Correlations between NDRG1 expression and clinical factors were analysed. An NDRG1 overexpression plasmid and NDRG1 siRNAs were transfected into bladder cancer cell lines. Cell biological behaviours were assessed by CCK-8, flow cytometry, wound healing and Transwell assays. Additionally, the influence of NDRG1 on epithelial-mesenchymal transition (EMT) was investigated by western blotting and real-time PCR. NDRG1 expression in urine from bladder cancer patients was examined by ELISA. NDRG1 protein levels were significantly increased in bladder cancer patients and correlated with tumour stage (p = 0.025), lymph node metastasis (p = 0.034) and overall survival (p = 0.016). Patients with high NDRG1 expression had poorer outcomes than those with low NDRG1 expression. NDRG1 overexpression was associated with increased cell proliferation, migration, and invasion and decreased apoptotic cell numbers; NDRG1 knockdown resulted in the inverse effects. Moreover, upregulated NDRG1 expression was associated with downregulated Cytokeratin 7 and Claudin-1 expression and upregulated N-cad, β-catenin and slug expression. Downregulated NDRG1 expression was associated with the inverse effects. Urine protein levels could distinguish bladder cancer patients from healthy controls, with an area under the curve of 0.909. NDRG1 promoted EMT in bladder cancer and could be an effective diagnostic and prognostic biomarker in bladder cancer patients.

Two mechanisms involving the autophagic and proteasomal pathways process the metastasis suppressor protein, N-myc downstream regulated gene 1

N-myc downstream regulated gene 1 (NDRG1) is an intriguing metastasis suppressor protein, which plays an important role in suppressing multiple oncogenic signaling pathways. Interestingly, multiple isoforms of NDRG1 have been identified, although the molecular mechanisms involved in their generation remains elusive. Herein, we demonstrate the role of two mechanisms involving autophagic and proteasomal machinery as part of an intricate system to generate different NDRG1 isoforms. Examining multiple pancreatic cancer cell-types using immunoblotting demonstrated three major isoforms of NDRG1 at approximately 41-, 46- and 47-kDa. The top NDRG1 band at 47-kDa was shown to be processed by the proteasome, followed by autophagic metabolism of the middle NDRG1 band at 46-kDa. The role of the proteasomal and autophagic pathways in NDRG1 processing was further confirmed by co-localization analysis of confocal images using PSMD9 and LC3 as classical markers of these respective pathways. All NDRG1 isoforms were demonstrated to be, at least in part, phosphorylated forms of the protein. Inhibition of two well-characterized upstream kinases of NDRG1, namely GSK3β and SGK1, resulted in decreased levels of the top NDRG1 band. Studies demonstrated that inhibition of GSK3β decreased levels of the top 47-kDa NDRG1 band, independent of its kinase activity, and this effect was not mediated via the proteasomal pathway. In contrast, the decrease in the top NDRG1 band at 47-kDa after SGK1 inhibition, was due to suppression of its kinase activity. Overall, these studies elucidated the complex and intricate regulatory pathways involving both proteasomal and autophagic processing of the metastasis suppressor protein, NDRG1.

Identification of genes required for eye development by high-throughput screening of mouse knockouts

Despite advances in next generation sequencing technologies, determining the genetic basis of ocular disease remains a major challenge due to the limited access and prohibitive cost of human forward genetics. Thus, less than 4,000 genes currently have available phenotype information for any organ system. Here we report the ophthalmic findings from the International Mouse Phenotyping Consortium, a large-scale functional genetic screen with the goal of generating and phenotyping a null mutant for every mouse gene. Of 4364 genes evaluated, 347 were identified to influence ocular phenotypes, 75% of which are entirely novel in ocular pathology. This discovery greatly increases the current number of genes known to contribute to ophthalmic disease, and it is likely that many of the genes will subsequently prove to be important in human ocular development and disease.

Bret Moore et al. from the International Mouse Phenotyping Consortium report the identification of 347 mouse genes that influence ocular phenotypes when knocked out. 75% of the identified genes have not previously been associated with any ocular pathology.