Iron-(Fe3+) dependent reactivation of telomerase drives colorectal cancers.

Over-consumption of iron-rich red meat and hereditary or genetic iron overload are associated with increased risk of colorectal carcinogenesis, yet the mechanistic basis of how metal-mediated signaling leads to oncogenesis remains enigmatic. Using fresh colorectal cancer (CRC) samples we identify Pirin, an iron sensor, that overcomes a rate-limiting step in oncogenesis, by re-activating the dormant human-reverse-transcriptase (hTERT) subunit of telomerase holoenzyme in an iron-(Fe3+)-dependent-manner and thereby drives CRCs. Chemical genetic screens combined with isothermal-dose response fingerprinting and mass-spectrometry identified a small molecule SP2509, that specifically inhibits Pirin-mediated hTERT reactivation in CRCs by competing with iron-(Fe3+) binding. Our findings, first to document how metal ions reactivate telomerase, provide a molecular mechanism for the well-known association between red meat, and increased incidence of CRCs. Small molecules like SP2509 represent a novel modality to target telomerase that acts as driver of 90% human cancers and is yet to be targeted in clinic.

Single-cell and bulk transcriptome sequencing identifies two epithelial tumor cell states and refines the consensus molecular classification of colorectal cancer.

The consensus molecular subtype (CMS) classification of colorectal cancer is based on bulk transcriptomics. The underlying epithelial cell diversity remains unclear. We analyzed 373,058 single-cell transcriptomes from 63 patients, focusing on 49,155 epithelial cells. We identified a pervasive genetic and transcriptomic dichotomy of malignant cells, based on distinct gene expression, DNA copy number and gene regulatory network. We recapitulated these subtypes in bulk transcriptomes from 3,614 patients. The two intrinsic subtypes, iCMS2 and iCMS3, refine CMS. iCMS3 comprises microsatellite unstable (MSI-H) cancers and one-third of microsatellite-stable (MSS) tumors. iCMS3 MSS cancers are transcriptomically more similar to MSI-H cancers than to other MSS cancers. CMS4 cancers had either iCMS2 or iCMS3 epithelium; the latter had the worst prognosis. We defined the intrinsic epithelial axis of colorectal cancer and propose a refined 'IMF' classification with five subtypes, combining intrinsic epithelial subtype (I), microsatellite instability status (M) and fibrosis (F).

DUSP16 promotes cancer chemoresistance through regulation of mitochondria-mediated cell death.

Drug resistance is a major obstacle to the treatment of most human tumors. In this study, we find that dual-specificity phosphatase 16 (DUSP16) regulates resistance to chemotherapy in nasopharyngeal carcinoma, colorectal cancer, gastric and breast cancer. Cancer cells expressing higher DUSP16 are intrinsically more resistant to chemotherapy-induced cell death than cells with lower DUSP16 expression. Overexpression of DUSP16 in cancer cells leads to increased resistance to cell death upon chemotherapy treatment. In contrast, knockdown of DUSP16 in cancer cells increases their sensitivity to treatment. Mechanistically, DUSP16 inhibits JNK and p38 activation, thereby reducing BAX accumulation in mitochondria to reduce apoptosis. Analysis of patient survival in head & neck cancer and breast cancer patient cohorts supports DUSP16 as a marker for sensitivity to chemotherapy and therapeutic outcome. This study therefore identifies DUSP16 as a prognostic marker for the efficacy of chemotherapy, and as a therapeutic target for overcoming chemoresistance in cancer.

The Effect of ACTN3 Gene Doping on Skeletal Muscle Performance.

Loss of expression of ACTN3, due to homozygosity of the common null polymorphism (p.Arg577X), is underrepresented in elite sprint/power athletes and has been associated with reduced muscle mass and strength in humans and mice. To investigate ACTN3 gene dosage in performance and whether expression could enhance muscle force, we performed meta-analysis and expression studies. Our general meta-analysis using a Bayesian random effects model in elite sprint/power athlete cohorts demonstrated a consistent homozygous-group effect across studies (per allele OR = 1.4, 95% CI 1.3-1.6) but substantial heterogeneity in heterozygotes. In mouse muscle, rAAV-mediated gene transfer overexpressed and rescued α-actinin-3 expression. Contrary to expectation, in vivo "doping" of ACTN3 at low to moderate doses demonstrated an absence of any change in function. At high doses, ACTN3 is toxic and detrimental to force generation, to demonstrate gene doping with supposedly performance-enhancing isoforms of sarcomeric proteins can be detrimental for muscle function. Restoration of α-actinin-3 did not enhance muscle mass but highlighted the primary role of α-actinin-3 in modulating muscle metabolism with altered fatiguability. This is the first study to express a Z-disk protein in healthy skeletal muscle and measure the in vivo effect. The sensitive balance of the sarcomeric proteins and muscle function has relevant implications in areas of gene doping in performance and therapy for neuromuscular disease.

Localized parakeratotic hyperkeratosis in sixteen Boston terrier dogs.

BACKGROUND: Although zinc responsive dermatosis is typically a disorder of Arctic breed dogs, this study identifies similar cutaneous lesions on the face and pressure points of Boston terrier dogs. HYPOTHESIS/OBJECTIVES: To document the clinical and histological features of localized parakeratotic hyperkeratosis of Boston terrier dogs, to determine if the lesions respond to zinc supplementation and to determine whether tissue zinc levels were decreased in affected versus unaffected dogs. MATERIAL AND METHODS: Sixteen Boston terrier dogs with similar gross and histological findings were identified retrospectively from two institutions. Follow-up information for nine dogs from one institution was obtained from referring veterinarians using a questionnaire. Tissue zinc levels were measured from formalin-fixed paraffin-embedded skin biopsy samples of affected and unaffected dogs using inductively coupled plasma mass spectrometry. RESULTS: Mild to severe parakeratotic hyperkeratosis with follicular involvement was present in all 16 cases. Of the nine dogs for which follow-up information was available, five dogs received oral zinc supplementation and four dogs had documented clinical improvement or resolution of dermatological lesions. The median skin zinc levels were not significantly different between affected and unaffected dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: To the best of the authors' knowledge this is the first report of localized parakeratotic hyperkeratosis in Boston terrier dogs, some of which improved with oral zinc supplementation. Prospective studies in Boston terrier dogs are warranted to document potential zinc deficiency (serum and/or tissue levels, pre- and post-treatment) and to objectively assess response to zinc supplementation and other therapies.

Interactions between angiotensin II and NF-kappaB-dependent pathways in modulating macrophage infiltration in experimental diabetic nephropathy.

NF-kappaB-dependent pathways play an important role in macrophage infiltration and kidney injury. NF-kappaB is regulated by angiotensin II (AII). However, the role of this pathway in diabetic nephropathy has not been clearly delineated. First, the activation of NF-kappaB, monocyte chemoattractant protein-1 (MCP-1), and macrophage infiltration in the diabetic kidney were explored, in a temporal manner. The active subunit of NF-kappaB, p65, was elevated in the diabetic animals in association with increased MCP-1 gene expression and macrophage infiltration. Second, the effects of treatment for 4 wk with the AII type 1 receptor antagonist valsartan, the AII type 2 receptor antagonist PD123319, or pyrrolidine dithiocarbamate, an inhibitor of NF-kappaB and on these parameters were assessed. These treatments were associated with a reduction in p65 activation, MCP-1 gene expression, and macrophage infiltration. These findings demonstrate a role for activation of NF-kappaB, in particular the p65 subunit, in the pathogenesis of early renal macrophage infiltration in experimental diabetes. In the context of the known proinflammatory effects of AII, it is postulated that the renoprotection conferred by angiotensin II receptor antagonism is at least partly related to the inhibition of NF-kappaB-dependent pathways.