δ-Catenin, a Wnt/β-catenin modulator, reveals inducible mutagenesis promoting cancer cell survival adaptation and metabolic reprogramming

Mutations of Wnt/β-catenin signaling pathway has essential roles in development and cancer. Although β-catenin and adenomatous polyposis coli (APC) gene mutations are well established and are known to drive tumorigenesis, discoveries of mutations in other components of the pathway lagged, which hinders the understanding of cancer mechanisms. Here we report that δ-catenin (gene designation: CTNND2), a primarily neural member of the β-catenin superfamily that promotes canonical Wnt/β-catenin/LEF-1-mediated transcription, displays exonic mutations in human prostate cancer and promotes cancer cell survival adaptation and metabolic reprogramming. When overexpressed in cells derived from prostate tumor xenografts, δ-catenin gene invariably gives rise to mutations, leading to sequence disruptions predicting functional alterations. Ectopic δ-catenin gene integrating into host chromosomes is locus nonselective. δ-Catenin mutations promote tumor development in mouse prostate with probasin promoter (ARR2PB)-driven, prostate-specific expression of Myc oncogene, whereas mutant cells empower survival advantage upon overgrowth and glucose deprivation. Reprogramming energy utilization accompanies the downregulation of glucose transporter-1 and poly (ADP-ribose) polymerase cleavage while preserving tumor type 2 pyruvate kinase expression. δ-Catenin mutations increase β-catenin translocation to the nucleus and hypoxia-inducible factor 1α (HIF-1α) expression. Therefore, introducing δ-catenin mutations is an important milestone in prostate cancer metabolic adaptation by modulating β-catenin and HIF-1α signaling under glucose shortage to amplify its tumor-promoting potential.

Successful treatment of renal light chain (AL) amyloidosis with bortezomib and dexamethasone (VD)

OBJECTIVE

To assess the efficacy and tolerability of bortezomib with dexamethasone for patients with renal light chain (AL) amyloidosis.

METHODS

Twelve newly diagnosed patients with renal AL amyloidosis were treated with a combination of bortezomib (1.3mg/m(2)/d iv, d1, 4, 8, 11) and dexamethasone (20mg/d iv drip, d1-4).

RESULTS

Median follow-up time was 22.5 months (range, 2.1-53.6). Ten patients were evaluable. Five out of 10 (50%) patients achieved complete hematologic responses (CHR), and totally 8/10 (80%) achieved hematologic responses (HR). Median time to hematologic response was 1 month. All patients who received HR had no hematologic progression during follow-up period. Five patients (50%) had kidney responses and the other 5 patients (50%) were stable. Median time to kidney response was 3 months. No patients presented renal progression during follow-up. One patient achieved PR after 4 cycles of VD and then received autologous peripheral blood stem cell transplantation. Two out of 10 evaluable patients without hematologic response had died with median overall survival of 8.2 months. Eight of them who had HR were alive with median follow-up time of 28.5 months. Infection (6/12) and fatigue (5/12) were the most frequent side effects. Three patients developed herpes zoster and had to discontinue therapy.

CONCLUSIONS

VD produces rapid, deep and durable hematological responses and renal responses in the majority of patients with newly diagnosed renal AL. It is well tolerated. This treatment may be a good option as first-line treatment for renal AL amyloidosis patients.

A new variable for SRS plan quality evaluation based on normal tissue sparing: the effect of prescription isodose levels

OBJECTIVE

A new dosimetric variable, dose-dropping speed (DDS), was proposed and used to evaluate normal tissue sparing among stereotactic radiosurgery (SRS) plans with different prescription isodose lines.

METHODS

40 plans were generated for 8 intracranial SRS cases, prescribing to isodose levels (IDLs) ranging from 50% to 90% in 10% increments. Whilst maintaining similar coverage and conformity, plans at different IDLs were evaluated in terms of normal tissue sparing using the proposed DDS. The DDS was defined as the greater decay coefficient in a double exponential decay fit of the dose drop-off outside the planning target volume (PTV), which models the steep portion of the drop-off. Provided that the prescription dose covers the whole PTV, a greater DDS indicates better normal tissue sparing.

RESULTS

Among all plans, the DDS was found to be the lowest for the prescription at 90% IDL and the highest for the prescription at 60% or 70%. The beam profile slope change in the penumbra and its field size dependence were explored and given as the physical basis of the findings.

CONCLUSION

A variable was proposed for SRS plan quality evaluation. Using this measure, prescriptions at 60% and 70% IDLs were found to provide best normal tissue sparing.

ADVANCES IN KNOWLEDGE

A new variable was proposed based on which normal tissue sparing was quantitatively evaluated, comparing different prescription IDLs in SRS.

K63-linked ubiquitination of FANCG is required for its association with the Rap80-BRCA1 complex to modulate homologous recombination repair of DNA interstand crosslinks

DNA interstrand crosslinks (ICLs) are extremely deleterious lesions that are repaired by homologous recombination (HR) through coordination of Fanconi anemia (FA) proteins and breast cancer susceptibility gene 1 (BRCA1) product, but the exact role these proteins have remains unclear. Here we report that FANCG was modified by the addition of lysine63-linked polyubiquitin chains (K63Ub) in response to DNA damage. We show that FANCG K63Ub was dispensable for monoubiquitination of FANCD2, but was required for FANCG to interact with the Rap80-BRCA1 (receptor-associated protein 80-BRCA1) complex for subsequent modulation of HR repair of ICLs induced by mitomycin C. Mutation of three lysine residues within FANCG to arginine (K182, K258 and K347, 3KR) reduced FANCG K63Ub modification, as well as its interaction with the Rap80-BRCA1 complex, and therefore impeded HR repair. In addition, we demonstrated that K63Ub-modified FANCG was deubiquitinated by BRCC36 complex in vitro and in vivo. Inhibition of BRCC36 resulted in increased K63Ub modification of FANCG. Taken together, our results identify a new role of FANCG in HR repair of ICL through K63Ub-mediated interaction with the Rap80-BRCA1 complex.

Orexin A-mediated stimulation of 3β-HSD expression and testosterone production through MAPK signaling pathways in primary rat Leydig cells

BACKGROUND

Orexin A (ORA) regulates food intake, energy metabolism, gastrointestinal and reproductive functions.

AIM

The purpose of this study was to demonstrate whether the expression of 3β-hydroxysteroid dehydrogenase (3β-HSD) and testosterone was stimulated by ORA and mediated through mitogen-activated protein kinases (MAPK) in rat Leydig cells.

METHODS

Primary Leydig cells were isolated from male rat testes, cultured, and treated with ORA under various conditions.

RESULTS

Orexin receptor 1 (OX (1) R) mRNA, but not orexin receptor 2 mRNA, was detected in primary Leydig cells. ORA up-regulated the expression of OX( 1) R mRNA and protein in a dose-responsive manner and increased the phosphorylation of extracellular receptor kinase 1/2 (ERK1/2) and p38 MAPK levels, but did not affect the phosphorylation of the JNK MAPK. Phosphorylation of ERK1/2 and p38 MAPKs by ORA was blocked with U0126 and SB203580 inhibitors, respectively. An OX(1)R-specific inhibitor, SB334867, also blocked the phosphorylation of ERK1/2 and p38 by ORA. Inhibitor treatment also blocked 3β-HSD expression and testosterone production.

CONCLUSIONS

These results demonstrate that ORA activation of OX(1)R up-regulates 3β-HSD expression and testosterone production via the ERK1/2 and p38 MAPKs signaling pathways in primary rat Leydig cells.

MMP-7 is upregulated by COX-2 and promotes proliferation and invasion of lung adenocarcinoma cells

Matrix metalloproteinases (MMPs) have been implicated in a variety of pathophysiological conditions, of which MMP-7 is expressed by tumor cells of epithelial and mesenchymal origin. However, the function of MMP-7 in human lung adenocarcinoma (LAC) is unclear. In the present study the expression of MMP-7 in LAC was examined by immunohistochemical assay using a tissue microarray procedure. A loss-of-function experiment was performed to explore the effects and molecular mechanisms of lentiviral vector-mediated MMP-7 siRNA (siMMP-7) on cell proliferation and invasive potential in LAC A549 cells, measured by MTT and Transwell assays, respectively. It was found that, the expression of MMP-7 protein in LAC was significantly increased compared with that in adjacent non-cancerous tissues (ANCT) (76.0% vs 44.0%, P<0.001), and positively correlated with lymph node metastases of the tumor (P=0.014). Furthermore, targeted inhibition of cyclooxygenase-2 (COX-2) by siRNA downregulated the expression of MMP-7 and inhibited invasion of LAC cells, and knockdown of MMP-7 suppressed tumor proliferation and invasion in LAC cells. Taken together, our findings indicate that increased expression of MMP-7 is associated with lymph node metastasis and upregulated by COX-2, and promotes the tumorigenesis of LAC, suggesting that MMP-7 may be a potential therapeutic target for the treatment of cancer.

An efficient algorithm for finding attractors in synchronous Boolean networks with biochemical applications

Self-organized systems, genetic regulatory systems and other living systems can be modeled as synchronous Boolean networks with stable states, which are also called state-cycle attractors (SCAs). This paper summarizes three classes of SCAs and presents a new efficient binary decision diagram based algorithm to find all SCAs of synchronous Boolean networks. After comparison with the tool BooleNet, empirical experiments with biochemical systems demonstrated the feasibility and efficiency of our approach.

Morphology variation and optical properties of ZnO nanostructures grown using bio-template

ZnO nanostructures of different morphologies were grown by immersing eggshell membranes into Zn(NO3)2 ethanol solution with different pH values and subsequently sintered at 500 degrees C. Effects of the solution pH value, immersing time and Mg incorporation on the nanostructure morphology and photoluminescence were studied. ZnO nanostructure morphology was very sensitive to pH value of the solution, immersing time and layer of the templates. Different morphologies of nanofibers, nanotubes, hexagonal nanosheets and hexagonal nanosheets with tips were grown. All nanostructures had strong green emission at 520 nm and weak ultraviolet emission at 377 nm. The green emission weakened in the interwoven nanofibers while the ultraviolet emission enhanced in the hexagonal nanosheets. Incorporation of Mg ions in the solution with a pH of 7 would result in combination of the interwoven nanofibers and enhance the green emission greatly. UV emission at 355 nm from ZnMgO alloys was observed in Mg incorporated nanofibers.

Growth and properties of ZnO/Zn(1-x)MgxO core/shell nanoparticles

ZnO/Zn(0.9)Mg(0.1)O core/shell nanoparticles have been grown by employing metal cupferronate complex as precursors in organic solvents. ZnO cores are grown by quickly injecting their precursor at 250 degrees C while the shells are performed by slowly injecting their precursors at different temperatures. The grown nanoparticles are characterized by X-ray diffraction, photoluminescence microscopy, and transmission electron microscopy. The effects of the shell growth temperatures and precursor injecting rate are studied. Zn(0.9)Mg(0.1)O shells can epitaxially grow on ZnO cores when the shell growth temperature is lowered to 200 degrees C and the shell precursor is supplied slowly at a rate of 0.1 mmol/h. Increaseing shell supply rate or shell growth temperature results in homogenous growth of Zn(0.9)Mg(0.1)O nanoparticles. The shell growth can dramatically enhance core emission and cause a red shift on the core band edge emission.