Citations

Significance Cancer cells reprogram their metabolism for optimal growth and survival. AMPK-activated protein kinase (AMPK) is a key energy sensor that controls many metabolic pathways including metabolic reprogramming. However, its role in cancer is poorly understood. Some studies claim that it has a tumor suppressor role while others show its protumor role. Two AMPK-activating compounds (including metformin, now in many clinical trials) are widely used to suppress cancer cell proliferation. We found that AMPK is abundantly expressed in high-grade gliomas and, in contrast to popular belief, these two AMPK activators suppressed glioma cell proliferation through unique AMPK-independent mechanisms.

Abstract Early-phase trials targeting the T-cell inhibitory molecule programmed cell death ligand 1 (PD-L1) have shown clinical efficacy in cancer. This study was undertaken to determine whether PD-L1 is overexpressed in triple-negative breast cancer (TNBC) and to investigate the loss of PTEN as a mechanism of PD-L1 regulation. The Cancer Genome Atlas (TCGA) RNA sequencing data showed significantly greater expression of the PD-L1 gene in TNBC (n = 120) compared with non-TNBC (n = 716; P < 0.001). Breast tumor tissue microarrays were evaluated for PD-L1 expression, which was present in 19% (20 of 105) of TNBC specimens. PD-L1+ tumors had greater CD8+ T-cell infiltrate than PD-L1− tumors (688 cells/mm vs. 263 cells/mm; P < 0.0001). To determine the effect of PTEN loss on PD-L1 expression, stable cell lines were generated using PTEN short hairpin RNA (shRNA). PTEN knockdown led to significantly higher cell-surface PD-L1 expression and PD-L1 transcripts, suggesting transcriptional regulation. Moreover, phosphoinositide 3-kinase (PI3K) pathway inhibition using the AKT inhibitor MK-2206 or rapamycin resulted in decreased PD-L1 expression, further linking PTEN and PI3K signaling to PD-L1 regulation. Coculture experiments were performed to determine the functional effect of altered PD-L1 expression. Increased PD-L1 cell surface expression by tumor cells induced by PTEN loss led to decreased T-cell proliferation and increased apoptosis. PD-L1 is expressed in 20% of TNBCs, suggesting PD-L1 as a therapeutic target in TNBCs. Because PTEN loss is one mechanism regulating PD-L1 expression, agents targeting the PI3K pathway may increase the antitumor adaptive immune responses. Cancer Immunol Res; 2(4); 361–70. ©2014 AACR.

Abstract Glycogen synthase kinase-3 (GSK-3), a constitutively active serine/threonine kinase, is a key regulator of numerous cellular processes ranging from glycogen metabolism to cell-cycle regulation and proliferation. Consistent with its involvement in many pathways, it has also been implicated in the pathogenesis of various human diseases, including type II diabetes, Alzheimer disease, bipolar disorder, inflammation, and cancer. Consequently, it is recognized as an attractive target for the development of new drugs. In the present study, we investigated the effect of both pharmacologic and genetic inhibition of GSK-3 in two different renal cancer cell lines. We have shown potent antiproliferative activity of 9-ING-41, a maleimide-based GSK-3 inhibitor. The antiproliferative activity is most likely caused by G0–G1 and G2–M phase arrest as evident from cell-cycle analysis. We have established that inhibition of GSK-3 imparted a differentiated phenotype in renal cancer cells. We have also shown that GSK-3 inhibition induced autophagy, likely as a result of imbalanced energy homeostasis caused by impaired glucose metabolism. In addition, we have demonstrated the antitumor activity of 9-ING-41 in two different subcutaneous xenograft renal cell carcinoma tumor models. To our knowledge, this is the first report describing autophagy induction due to GSK-3 inhibition in renal cancer cells. Mol Cancer Ther; 13(2); 285–96. ©2013 AACR.

Summary A low‐diversity microbial community, dominated by the γ ‐proteobacterium H alomonas sulfidaeris , was detected in samples of warm saline formation porewater collected from the C ambrian Mt. S imon S andstone in the I llinois B asin of the N orth A merican M idcontinent (1.8 km/5872 ft burial depth, 50° C , pH 8, 181 bars pressure). These highly porous and permeable quartz arenite sandstones are directly analogous to reservoirs around the world targeted for large‐scale hydrocarbon extraction, as well as subsurface gas and carbon storage. A new downhole low‐contamination subsurface sampling probe was used to collect in situ formation water samples for microbial environmental metagenomic analyses. Multiple lines of evidence suggest that this H . sulfidaeris ‐dominated subsurface microbial community is indigenous and not derived from drilling mud microbial contamination. Data to support this includes V 1‐ V 3 pyrosequencing of formation water and drilling mud, as well as comparison with previously published microbial analyses of drilling muds in other sites. Metabolic pathway reconstruction, constrained by the geology, geochemistry and present‐day environmental conditions of the Mt . S imon S andstone, implies that H . sulfidaeris ‐dominated subsurface microbial community may utilize iron and nitrogen metabolisms and extensively recycle indigenous nutrients and substrates. The presence of aromatic compound metabolic pathways suggests this microbial community can readily adapt to and survive subsurface hydrocarbon migration.

The study objectives were: to mine the complete exome to identify putative rare single nucleotide variants (SNVs) associated with irritable bowel syndrome (IBS)-diarrhea (IBS-D) phenotype, to assess genes that regulate bile acids in IBS-D, and to explore univariate associations of SNVs with symptom phenotype and quantitative traits in an independent IBS cohort. Using principal components analysis, we identified two groups of IBS-D ( n = 16) with increased fecal bile acids: rapid colonic transit or high bile acids synthesis. DNA was sequenced in depth, analyzing SNVs in bile acid genes ( ASBT, FXR, OSTα/β, FGF19, FGFR4, KLB, SHP, CYP7A1, LRH-1, and FABP6). Exome findings were compared with those of 50 similar ethnicity controls. We assessed univariate associations of each SNV with quantitative traits and a principal components analysis and associations between SNVs in KLB and FGFR4 and symptom phenotype in 405 IBS, 228 controls and colonic transit in 70 IBS-D, 71 IBS-constipation. Mining the complete exome did not reveal significant associations with IBS-D over controls. There were 54 SNVs in 10 of 11 bile acid-regulating genes, with no SNVs in FGF19; 15 nonsynonymous SNVs were identified in similar proportions of IBS-D and controls. Variations in KLB (rs1015450, downstream) and FGFR4 [rs434434 (intronic), rs1966265, and rs351855 (nonsynonymous)] were associated with colonic transit (rs1966265; P = 0.043), fecal bile acids (rs1015450; P = 0.064), and principal components analysis groups (all 3 FGFR4 SNVs; P < 0.05). In the 633-person cohort, FGFR4 rs434434 was associated with symptom phenotype ( P = 0.027) and rs1966265 with 24-h colonic transit ( P = 0.066). Thus exome sequencing identified additional variants in KLB and FGFR4 associated with bile acids or colonic transit in IBS-D.

Abstract Ovarian cancer is a clinically and molecularly heterogeneous disease. The driving forces behind this variability are unknown. Here, we report wide variation in the expression of the DNA cytosine deaminase APOBEC3B, with elevated expression in the majority of ovarian cancer cell lines (three SDs above the mean of normal ovarian surface epithelial cells) and high-grade primary ovarian cancers. APOBEC3B is active in the nucleus of several ovarian cancer cell lines and elicits a biochemical preference for deamination of cytosines in 5′-TC dinucleotides. Importantly, examination of whole-genome sequence from 16 ovarian cancers reveals that APOBEC3B expression correlates with total mutation load as well as elevated levels of transversion mutations. In particular, high APOBEC3B expression correlates with C-to-A and C-to-G transversion mutations within 5′-TC dinucleotide motifs in early-stage high-grade serous ovarian cancer genomes, suggesting that APOBEC3B-catalyzed genomic uracil lesions are further processed by downstream DNA "repair" enzymes including error-prone translesion polymerases. These data identify a potential role for APOBEC3B in serous ovarian cancer genomic instability. Cancer Res; 73(24); 7222–31. ©2013 AACR.

Summary The transcription factor forkhead box N4 (Foxn4) is a key regulator in a variety of biological processes during development. In particular, Foxn4 plays an essential role in the genesis of horizontal and amacrine neurons from neural progenitors in the vertebrate retina. Although the functions of Foxn4 have been well established, the transcriptional regulation of Foxn4 expression during progenitor cell differentiation remains unclear. Here, we report that an evolutionarily conserved 129 bp noncoding DNA fragment (Foxn4CR4.2 or CR4.2), located ∼26 kb upstream of Foxn4 transcription start site, functions as a cis-element for Foxn4 regulation. CR4.2 directs gene expression in Foxn4-positive cells, primarily in progenitors, differentiating horizontal and amacrine cells. We further determined that the gene regulatory activity of CR4.2 is modulated by Meis1 binding motif, which is bound and activated by Meis1 transcription factor. Deletion of the Meis1 binding motif or knockdown of Meis1 expression abolishes the gene regulatory activity of CR4.2. In addition, knockdown of Meis1 expression diminishes the endogenous Foxn4 expression and affects cell lineage development. Together, we demonstrate that CR4.2 and its interacting Meis1 transcription factor play important roles in regulating Foxn4 expression during early retinogenesis. These findings provide new insights into molecular mechanisms that govern gene regulation in retinal progenitors and specific cell lineage development.

Objectives/Hypothesis Pediatric obstructive sleep apnea syndrome ( OSAS ) is a common disorder with serious clinical implications if left untreated. The recommended initial treatment for pediatric patients with obstructive sleep apnea syndrome ( OSAS ) is adenotonsillectomy. However, recent reports have shown variable surgical results with adenotonsillectomy in the treatment of pediatric OSAS . Study Design Prospective, controlled study. Methods From April 2007 to August 2010, 24 participants were assigned alternatively to either adenotonsillectomy with pillar suturing (intervention group) or adenotonsillectomy alone (control group). Result The average improvement in apnea hypopnea index ( AHI ) was 42.6% in the control group and 79.9% in the intervention group ( P =0.037). The success rate was 50% in the control group and 91.6% in the intervention group ( P =0.034). Six patients (50%) in the intervention group achieved complete resolution of pediatric OSAS , as defined by an AHI <1/hour, compared to 2 patients (16.7%) in the control group ( P =0.097). Conclusion Adenotonsillectomy with pillar suturing showed significant improvement in treating pediatric patients with OSAS compared to adenotonsillectomy alone. The procedure is simple and safe. Level of Evidence 4. Laryngoscope , 123:2574–2578, 2013