A multidimensional network approach reveals microRNAs as determinants of the mesenchymal colorectal cancer subtype.

Colorectal cancer (CRC) is a heterogeneous disease posing a challenge for accurate classification and treatment of this malignancy. There is no common genetic molecular feature that would allow for the identification of patients at risk for developing recurrences and thus selecting patients who would benefit from more stringent therapies still poses a major clinical challenge. Recently, an international multicenter consortium (CRC Subtyping Consortium) was established aiming at the classification of CRC patients in biologically homogeneous CRC subtypes. Four consensus molecular subtypes (CMSs) were identified, of which the mesenchymal CMS4 presented with worse prognosis signifying the importance of identifying these patients. Despite the large number of samples analyzed and their clear association with unifying biological programs and clinical features, single-driver mutations could not be identified and patients are heterogeneous with regard to currently used clinical markers. We therefore set out to define the regulatory mechanisms underlying the distinct gene expression profiles using a network-based approach involving multiple molecular modalities such as gene expression, methylation levels and microRNA (miR) expression. The miR-200 family presented as the most powerful determinant of CMS4-specific gene expression, tuning the majority of genes differentially expressed in the poor prognosis subtype, including genes associated with the epithelial-mesenchymal transition program. Furthermore, our data show that two epigenetic marks, namely the methylation of the two miR-200 promoter regions, can identify tumors belonging to the mesenchymal subtype and is predictive of disease-free survival in CRC patients. Importantly, epigenetic silencing of the miR-200 family is also detected in epithelial CRC cell lines that belong to the mesenchymal CMS. We thus show that determining regulatory networks is a powerful strategy to define drivers of distinct cancer subtypes, which possess the ability to identify subtype affiliation and to shed light on biological behavior.

FGF-21, a novel metabolic regulator, has a robust neuroprotective role and is markedly elevated in neurons by mood stabilizers.

Fibroblast growth factor-21 (FGF-21) is a new member of the FGF super-family and an important endogenous regulator of glucose and lipid metabolism. It has been proposed as a therapeutic target for diabetes and obesity. Its function in the central nervous system (CNS) remains unknown. Previous studies from our laboratory demonstrated that aging primary neurons are more vulnerable to glutamate-induced excitotoxicity, and that co-treatment with the mood stabilizers lithium and valproic acid (VPA) induces synergistic neuroprotective effects. This study sought to identify molecule(s) involved in these synergistic effects. We found that FGF-21 mRNA was selectively and markedly elevated by co-treatment with lithium and VPA in primary rat brain neurons. FGF-21 protein levels were also robustly increased in neuronal lysates and culture medium following lithium-VPA co-treatment. Combining glycogen synthase kinase-3 (GSK-3) inhibitors with VPA or histone deacetylase (HDAC) inhibitors with lithium synergistically increased FGF-21 mRNA levels, supporting that synergistic effects of lithium and VPA are mediated via GSK-3 and HDAC inhibition, respectively. Exogenous FGF-21 protein completely protected aging neurons from glutamate challenge. This neuroprotection was associated with enhanced Akt-1 activation and GSK-3 inhibition. Lithium-VPA co-treatment markedly prolonged lithium-induced Akt-1 activation and augmented GSK-3 inhibition. Akt-1 knockdown markedly decreased FGF-21 mRNA levels and reduced the neuroprotection induced by FGF-21 or lithium-VPA co-treatment. In addition, FGF-21 knockdown reduced lithium-VPA co-treatment-induced Akt-1 activation and neuroprotection against excitotoxicity. Together, our novel results suggest that FGF-21 is a key mediator of the effects of these mood stabilizers and a potential new therapeutic target for CNS disorders.

Decreased mitochondrial priming determines chemoresistance of colon cancer stem cells.

Tumor heterogeneity is in part determined by the existence of cancer stem cells (CSCs) and more differentiated tumor cells. CSCs are considered to be the tumorigenic root of cancers and suggested to be chemotherapy resistant. Here we exploited an assay that allowed us to measure chemotherapy-induced cell death in CSCs and differentiated tumor cells simultaneously. This confirmed that CSCs are selectively resistant to conventional chemotherapy, which we revealed is determined by decreased mitochondrial priming. In agreement, lowering the anti-apoptotic threshold using ABT-737 and WEHI-539 was sufficient to enhance chemotherapy efficacy, whereas ABT-199 failed to sensitize CSCs. Our data therefore point to a crucial role of BCLXL in protecting CSCs from chemotherapy and suggest that BH3 mimetics, in combination with chemotherapy, can be an efficient way to target chemotherapy-resistant CSCs.

Effects of human thyroxine-binding globulin and prealbumin on the reverse flow of thyroid hormones from extravascular space into the bloodstream in rabbits.

A plasma fraction rich in thyroid hormone-binding globulin (hTBG, human thyropexin) was injected iv into rabbits in order to see whether thyroid hormone concentrations in plasma would increase by return of T3 and T4 from the extravascular space. For this purpose, both [125I]T3 and [131I]T4 were simultaneously injected. After 1 h, or after 16 h in another series of experiments, 50 mg hTBG were injected iv. Thereafter, the mean radioactivity of both [125I]T3 and [131I]T4 in the plasma rose, and reached its peak 20-30 min after hTBG injection; [125I]T3 and [131I]T4 returned to the preinjection value slowly, after more than 3 h. When hTBG was injected 15-16 h after the radioactive hormones, the mean radioactivity of [125I]T3 reached its peak about 1 h after hTBG injection and returned to the base value after approximately 5.5 h, [131I]T4 reached its peak about 1 h after hTBG injection and returned to the base value within 12 h. After injection of hTBG, total T4 and T3 concentrations in plasma increased about 3- to 5-fold over the base values. At the same time, the percentage of both, free T4 and free T3 dropped instantly whereas absolute free T4 and free T3 values remained almost constant. After injection of 500 mg transthyretin (hTBPA), a similar flux of [125I]T3 and [131I]T4 was observed, whereas 500 mg human serum albumin were ineffective. These marked effects of injected hTBG and hTBPA on the serum levels of [125I]T3, [131I]T4, and total T3 indicate that reentry of T3 and T4 into the intravascular compartment is an important component of thyroid hormone distribution and transport. As can be anticipated from the animal experiments, the efficiency of plasmapheresis or hemofiltration methods may be improved by previous application of large doses of hTBPA or hTBG in cases of thyrotoxicosis.

A decade of Dial-a-Dietitian in Columbus, Ohio.

Data gathered during the decade 1962-1972 on Dial-a-Dietitian as a community service of the Columbus Dietetic Association support the usefulness of this unique experiment in community nutrition education. The image of the dietitian as a spokesman for the science of nutrition and as a contributing member of the health team should be advanced in every way possible. Dial-a-Dietitian is a realistic vehicle which offers much needed assistance. There emerges the need for individualized diet counseling with a fee-for-service and referral from the physician or dentist. Dial-a-Dietitian might then be in a position to direct its enery and resources toward better serving community needs with respect to normal nutrition education. District dietetic associations should define and redefine the objectives to be served by the Dial-a-Diettian program as these relate to specific and changing requirements.