UHRF1 predicts poor prognosis by triggering cell cycle in lung adenocarcinoma.

Accumulating evidence suggests that ubiquitin-like with plant homeodomain and ring finger domains 1 (UHRF1) is overexpressed in non-small cell lung cancer (NSCLC); however, the expression and function of UHRF1 in the subtype of NSCLC are still unclear. Here, we investigate the expression and prognosis traits of UHRF1 in large NSCLC cohorts and explore the molecular characters during UHRF1 up-regulation. We find that UHRF1 is predominantly overexpressed in lung squamous cell carcinoma (SCC). Surprisingly, the up-regulated UHRF1 is only associated with the overall survival of lung adenocarcinoma (ADC) and knockdown of UHRF1 dramatically attenuates ADC tumorigenesis. Mechanically, we identify a hub gene that includes a total of 55 UHRF1-related genes, which are tightly associated with cell cycle pathway and yield to the poor clinical outcome in ADC patients. What's more, we observe knockdown of UHRF1 only affects ADC cells cycle and induces cell apoptosis. These results suggest that up-regulated UHRF1 only contributes to lung ADC survival by triggering cell cycle pathway, and it may be a prognostic biomarker for lung ADC patients.

PTEN in the maintenance of genome integrity: From DNA replication to chromosome segregation.

Faithful DNA replication and accurate chromosome segregation are the key machineries of genetic transmission. Disruption of these processes represents a hallmark of cancer and often results from loss of tumor suppressors. PTEN is an important tumor suppressor that is frequently mutated or deleted in human cancer. Loss of PTEN has been associated with aneuploidy and poor prognosis in cancer patients. In mice, Pten deletion or mutation drives genomic instability and tumor development. PTEN deficiency induces DNA replication stress, confers stress tolerance, and disrupts mitotic spindle architecture, leading to accumulation of structural and numerical chromosome instability. Therefore, PTEN guards the genome by controlling multiple processes of chromosome inheritance. Here, we summarize current understanding of the PTEN function in promoting high-fidelity transmission of genetic information. We also discuss the PTEN pathways of genome maintenance and highlight potential targets for cancer treatment.

Expression and purification of the trypsin inhibitor from tartary buckwheat in Pichia pastoris and its novel toxic effect on Mamestra brassicae larvae.

The gene of the trypsin inhibitor of tartary buckwheat (Fagopyrum tataricum) was successfully cloned, expressed in Pichia pastoris and tested for regulatory effects on insect growth. The three significant factors were optimized by single-factor experiments and central composite design in response surface methodology. Proteins were efficiently expressed at levels of 489.6-527.4 U/mg in shaken flasks. The trypsin inhibitor from tartary buckwheat (FtTI) was purified by affinity chromatography and centrifugal ultrafiltration. The purified FtTI efficiently inhibited trypsin protease activity by competitive inhibition with a Ki value 1.5 nM. The molecular mass of the purified protein was approximately 13.8 kDa. FtTI had a higher toxic killing effect on Mamestra brassicae larvae. The median lethal concentration for the larvae was 15 µg/mL.

CD8+ T cell metabolic flexibility elicited by CD28-ARS2 axis-driven alternative splicing of PKM supports antitumor immunity.

Metabolic flexibility has emerged as a critical determinant of CD8+ T-cell antitumor activity, yet the mechanisms driving the metabolic flexibility of T cells have not been determined. In this study, we investigated the influence of the nuclear cap-binding complex (CBC) adaptor protein ARS2 on mature T cells. In doing so, we discovered a novel signaling axis that endows activated CD8+ T cells with flexibility of glucose catabolism. ARS2 upregulation driven by CD28 signaling reinforced splicing factor recruitment to pre-mRNAs and affected approximately one-third of T-cell activation-induced alternative splicing events. Among these effects, the CD28-ARS2 axis suppressed the expression of the M1 isoform of pyruvate kinase in favor of PKM2, a key determinant of CD8+ T-cell glucose utilization, interferon gamma production, and antitumor effector function. Importantly, PKM alternative splicing occurred independently of CD28-driven PI3K pathway activation, revealing a novel means by which costimulation reprograms glucose metabolism in CD8+ T cells.

MicroRNA miR-491-5p targeting both TP53 and Bcl-XL induces cell apoptosis in SW1990 pancreatic cancer cells through mitochondria mediated pathway.

MicroRNA (miRNA) actively participates in a broad range of cellular processes such as proliferation, differentiation, cell survival and apoptosis. Deregulated expression of miRNA may affect cell growth and eventually lead to cancer. In this study, we found that hsa-miR491-5p (miR491-5p) displays a significantly high level of expression in normal human pancreas tissue versus pancreatic cancer cells. Targeted site prediction indicated that both Bcl-XL and TP53 contain miR-491-5p recognizing sites in their 3' UTRs. Overexpression of miR-491-5p in the pancreatic cancer cell line SW1990 effectively inhibited both endogenous Bcl-XL and TP53 gene expressions. Mutagenesis at the seed match region of both targeted genes further confirmed the specificity of miR491-5p recognition. Cell proliferation rate was inversely related to the increased doses of miR-491-5p. Flow cytometric analysis showed that the proportions of total apoptotic and early apoptotic cells were significantly induced as the dose of miR491-5p increased. Moreover, a mechanistic study indicated that miR-R491-5p-mediated cell apoptosis was associated with the activation of intrinsic mitochondria mediated pathways. miR491-5p also markedly inhibited mitogenic signaling pathways such as STAT3 and PI-3K/Akt, but not Ras/MAPK. Thus, our results demonstrated that miR491-5p could effectively target both Bcl-xL and TP53 and induce cell apoptosis independent of TP53.

In vivo library screening identifies the metabolic enzyme aldolase A as a promoter of metastatic lung colonization.

Elucidations of the factors that promote the growth of disseminated tumor cells (DTCs) into life-threatening lesions stand to provide much needed prognostic and therapeutic targets of translational utility for patients with metastatic cancer. To identify such regulators, we conducted gain-of-function cDNA library screening to discover genes that foster prostate cancer cell colonization of mouse lungs as an experimental model. Our efforts identified the metabolic enzyme aldolase A (ALDOA) as a driver of cancer cell motility, anchorage-independent growth, and metastatic colonization, and as a prognosticator of adverse patient outcome across many malignancies, including prostate, breast, pancreatic, and liver cancers. Metabolomics coupled with biochemical and functional analyses revealed that ALDOA triggered the activation of adenosine-5'-monophosphate (AMP)-activated protein kinase (AMPK), which we demonstrate played essential promalignant activities in ALDOA-expressing cells. Collectively, these findings unveiled vivo approaches to identify metastatic colonization regulators and uncovered previously undescribed roles for ALDOA-AMPK pathway in tumor progression.

Isoform Switching as a Mechanism of Acquired Resistance to Mutant Isocitrate Dehydrogenase Inhibition.

Somatic mutations in cytosolic or mitochondrial isoforms of isocitrate dehydrogenase (IDH1 or IDH2, respectively) contribute to oncogenesis via production of the metabolite 2-hydroxyglutarate (2HG). Isoform-selective IDH inhibitors suppress 2HG production and induce clinical responses in patients with IDH1- and IDH2-mutant malignancies. Despite the promising activity of IDH inhibitors, the mechanisms that mediate resistance to IDH inhibition are poorly understood. Here, we describe four clinical cases that identify mutant IDH isoform switching, either from mutant IDH1 to mutant IDH2 or vice versa, as a mechanism of acquired clinical resistance to IDH inhibition in solid and liquid tumors. SIGNIFICANCE: IDH-mutant cancers can develop resistance to isoform-selective IDH inhibition by "isoform switching" from mutant IDH1 to mutant IDH2 or vice versa, thereby restoring 2HG production by the tumor. These findings underscore a role for continued 2HG production in tumor progression and suggest therapeutic strategies to prevent or overcome resistance.This article is highlighted in the In This Issue feature, p. 1494.

Cell Cycle Control by PTEN.

Continuous and error-free chromosome inheritance through the cell cycle is essential for genomic stability and tumor suppression. However, accumulation of aberrant genetic materials often causes the cell cycle to go awry, leading to malignant transformation. In response to genotoxic stress, cells employ diverse adaptive mechanisms to halt or exit the cell cycle temporarily or permanently. The intrinsic machinery of cycling, resting, and exiting shapes the cellular response to extrinsic stimuli, whereas prevalent disruption of the cell cycle machinery in tumor cells often confers resistance to anticancer therapy. Phosphatase and tensin homolog (PTEN) is a tumor suppressor and a guardian of the genome that is frequently mutated or deleted in human cancer. Moreover, it is increasingly evident that PTEN deficiency disrupts the fundamental processes of genetic transmission. Cells lacking PTEN exhibit cell cycle deregulation and cell fate reprogramming. Here, we review the role of PTEN in regulating the key processes in and out of cell cycle to optimize genomic integrity.

PTEN at the interface of immune tolerance and tumor suppression.

BACKGROUND: PTEN is well known to function as a tumor suppressor that antagonizes oncogenic signaling and maintains genomic stability. The PTEN gene is frequently deleted or mutated in human cancers and the wide cancer spectrum associated with PTEN deficiency has been recapitulated in a variety of mouse models of Pten deletion or mutation. Pten mutations are highly penetrant in causing various types of spontaneous tumors that often exhibit resistance to anticancer therapies including immunotherapy. Recent studies demonstrate that PTEN also regulates immune functionality. OBJECTIVE: To understand the multifaceted functions of PTEN as both a tumor suppressor and an immune regulator. METHODS: This review will summarize the emerging knowledge of PTEN function in cancer immunoediting. In addition, the mechanisms underlying functional integration of various PTEN pathways in regulating cancer evolution and tumor immunity will be highlighted. RESULTS: Recent preclinical and clinical studies revealed the essential role of PTEN in maintaining immune homeostasis, which significantly expands the repertoire of PTEN functions. Mechanistically, aberrant PTEN signaling alters the interplay between the immune system and tumors, leading to immunosuppression and tumor escape. CONCLUSION: Rational design of personalized anti-cancer treatment requires mechanistic understanding of diverse PTEN signaling pathways in modulation of the crosstalk between tumor and immune cells.

A Murine Model for Quantitative, Real-Time Evaluation of Convection-Enhanced Delivery (RT-CED) Using an 18[F]-Positron Emitting, Fluorescent Derivative of Dasatinib.

The blood brain barrier can limit the efficacy of systemically delivered drugs in treating neurological malignancies; therefore, alternate routes of drug administration must be considered. The Abl-kinase inhibitor, dasatinib, is modified to give compound 1 ([18F]-1) so that 18F-positron emission tomography (PET) and fluorescent imaging can both be used to observe drug delivery to murine orthotopic glioma. In vitro Western blotting, binding studies (IC50 = 22 ± 5 nmol/L), and cell viability assays (IC50 = 46 ± 30 nmol/L) confirm nanomolar, in vitro effectiveness of [18F]-1, a dasatinib derivative that is visible by 18F-PET and fluorescence. [18F]-1 is used to image dynamic direct drug delivery via two different drug delivery techniques to orthotopic murine brainstem glioma (mBSG) bearing mice. Convection enhanced delivery (CED) delivers higher concentrations of drug to glioma-containing volumes versus systemic, tail-vein delivery. Accurate delivery and clearance data pertaining to dasatinib are observed, providing personalized information that is important in dosimetry and redosing. Cases of missed drug delivery are immediately recognized by PET/CT, allowing for prompt intervention in the case of missed delivery. Mol Cancer Ther; 16(12); 2902-12. ©2017 AACR.

PTEN regulates PLK1 and controls chromosomal stability during cell division.

PTEN functions as a guardian of the genome through multiple mechanisms. We have previously established that PTEN maintains the structural integrity of chromosomes. In this report, we demonstrate a fundamental role of PTEN in controlling chromosome inheritance to prevent gross genomic alterations. Disruption of PTEN or depletion of PTEN protein phosphatase activity causes abnormal chromosome content, manifested by enlarged or polyploid nuclei. We further identify polo-like kinase 1 (PLK1) as a substrate of PTEN phosphatase. PTEN can physically associate with PLK1 and reduce PLK1 phosphorylation in a phosphatase-dependent manner. We show that PTEN deficiency leads to PLK1 phosphorylation and that a phospho-mimicking PLK1 mutant causes polyploidy, imitating functional deficiency of PTEN phosphatase. Inhibition of PLK1 activity or overexpression of a non-phosphorylatable PLK1 mutant reduces the polyploid cell population. These data reveal a new mechanism by which PTEN controls genomic stability during cell division.

NOK mediated mitogenic signaling is altered by P203L and V395I mutations.

The novel oncogene with kinase-domain (NOK), is an atypical receptor protein tyrosine kinase with potent oncogenic potential. In the current study, we generated two point mutations (P203L and V395I) on NOK gene. NOK(P203L) is identical to serine/threonine/tyrosine kinase 1 (STYK1), the aliases of NOK, while the V395I mutation was recovered from human glioblastoma. Both mutations did not impair NOK kinase activities, but V395I inhibited NOK autophosphorylation. Although with overall inhibition, both STYK1 and V395I affected the activities of extracellular regulated protein kinase (ERK), Akt and signal transducer and activator of transcription (STAT) differently in HEK293T cells versus HeLa and BaF3 stable cells The proliferation potentials for both STYK1 and V395I were significantly inhibited. Single mutation at either site was sufficient to abolish the IL-3 independent growth and the anchor-independent growth of of BaF3 stable cells. Overall, our data indicates that both P203 and V395 residues on NOK are important for NOK mediated mitogenic signaling, and the substitutions of P203L and V395I may selectively affect certain mitogenic signaling cascades in a tissue specific manner.