Development of anchialine cave habitats and karst subterranean estuaries since the last ice age.

Extinction models generally predict that coastal and neritic fauna benefit during sea-level rise (transgression), whereas sea-level retreat (regression) diminishes their suitable habitat area and promotes evolutionary bottlenecks. Sea-level change also impacts terrestrial island biogeography, but it remains a challenge to evidence how sea-level rise impacts aquatic island biogeography, especially in the subterranean realm. Karst subterranean estuaries (KSEs) occur globally on carbonate islands and platforms, and they are populated by globally-dispersed, ancient ecosystems (termed anchialine). Anchialine fauna currently exhibit a disjunct biogeography that cannot be completely explained by plate tectonic-imposed vicariance. Here we provide evidence that anchialine ecosystems can experience evolutionary bottlenecks caused by habitat reduction during transgression events. Marine-adapted anchialine fauna benefit from habitat expansion during transgressions, but fresh- and brackish-adapted fauna must emigrate, evolve to accommodate local habitat changes, or are regionally eliminated. Phanerozoic transgressions relative to long-term changes in subsidence and relief of regional lithology must be considered for explaining biogeography, evolution, local extirpation or complete extinction of anchialine fauna. Despite the omission of this entire category of environments and animals in climate change risk assessments, the results indicate that anchialine fauna on low-lying islands and platforms that depend upon meteoric groundwater are vulnerable to habitat changes caused by 21st century sea-level rise.

RSK2 is a new Pim2 target with pro-survival functions in FLT3-ITD-positive acute myeloid leukemia.

Acute myeloid leukemia (AML) with the FLT3 internal tandem duplication (FLT3-ITD AML) accounts for 20-30% of AML cases. This subtype usually responds poorly to conventional therapies, and might become resistant to FLT3 tyrosine kinase inhibitors (TKIs) due to molecular bypass mechanisms. New therapeutic strategies focusing on resistance mechanisms are therefore urgently needed. Pim kinases are FLT3-ITD oncogenic targets that have been implicated in FLT3 TKI resistance. However, their precise biological function downstream of FLT3-ITD requires further investigation. We performed high-throughput transcriptomic and proteomic analyses in Pim2-depleted FLT3-ITD AML cells and found that Pim2 predominantly controlled apoptosis through Bax expression and mitochondria disruption. We identified ribosomal protein S6 kinase A3 (RSK2), a 90 kDa serine/threonine kinase involved in the mitogen-activated protein kinase cascade encoded by the RPS6KA3 gene, as a novel Pim2 target. Ectopic expression of an RPS6KA3 allele rescued the viability of Pim2-depleted cells, supporting the involvement of RSK2 in AML cell survival downstream of Pim2. Finally, we showed that RPS6KA3 knockdown reduced the propagation of human AML cells in vivo in mice. Our results point to RSK2 as a novel Pim2 target with translational therapeutic potential in FLT3-ITD AML.

Chimerism analysis in peripheral blood using indel quantitative real-time PCR is a useful tool to predict post-transplant relapse in acute leukemia.

Detection of increasing mixed chimerism (IMC) using standard PCR correlates with relapse after allo-SCT for acute leukemias (ALs). Quantitative real-time PCR of insertion/deletion polymorphism (indel qrtPCR) is a much more sensitive method, which can be performed on peripheral blood. We studied the significance of low increases of recipient cells (0.1%) detected by indel qrtPCR in a cohort of 89 transplants. We did not observe relapse among the 32 patients with no IMC. Fifty-seven patients presented a first IMC, which was followed by four different scenarios: a decreasing MC (26 cases, no relapse), a stable MC (1 case, 1 relapse), a second IMC (24 cases, 15 relapse) or no control of chimerism (6 cases, 5 relapses). In multivariate analysis, detection of two successive IMCs was strongly associated with relapse (hazard ratio (HR): 9.4, 95% confidence interval (CI): 3.8-23; P<0.0001). Among the 57 patients who presented at least one IMC, 27 underwent immunomodulation (tapering of immunosuppression or donor lymphocyte injection), leading to a 1-year relapse rate of 15.7% vs 57.6% in the 30 other patients (P=0.0007). Altogether, these results indicate that chimerism analysis using indel qrtPCR in peripheral blood is a useful tool for detection of relapse in patients transplanted for AL.

The dual mTORC1 and mTORC2 inhibitor AZD8055 has anti-tumor activity in acute myeloid leukemia.

The serine/threonine kinase mammalian target of rapamycin (mTOR) is crucial for cell growth and proliferation, and is constitutively activated in primary acute myeloid leukemia (AML) cells, therefore representing a major target for drug development in this disease. We show here that the specific mTOR kinase inhibitor AZD8055 blocked mTORC1 and mTORC2 signaling in AML. Particularly, AZD8055 fully inhibited multisite eIF4E-binding protein 1 phosphorylation, subsequently blocking protein translation, which was in contrast to the effects of rapamycin. In addition, the mTORC1-dependent PI3K/Akt feedback activation was fully abrogated in AZD8055-treated AML cells. Significantly, AZD8055 decreased AML blast cell proliferation and cell cycle progression, reduced the clonogenic growth of leukemic progenitors and induced caspase-dependent apoptosis in leukemic cells but not in normal immature CD34+ cells. Interestingly, AZD8055 strongly induced autophagy, which may be either protective or cell death inducing, depending on concentration. Finally, AZD8055 markedly increased the survival of AML transplanted mice through a significant reduction of tumor growth, without apparent toxicity. Our current results strongly suggest that AZD8055 should be tested in AML patients in clinical trials.

The mdr1a-/- mouse model of spontaneous colitis: a relevant and appropriate animal model to study inflammatory bowel disease.

There are many types of colitis models in animals that researchers use to elucidate the mechanism of action of human inflammatory bowel disease (IBD). These models are also used to test novel therapeutics and therapeutic treatment regimens. Here, we will review the characteristics of the mdr1a -/- model of spontaneous colitis that we believe make this model an important part of the IBD researcher's toolbox. We will also share new data that will reinforce the fact that this model is relevant in the study of IBD. Mdr1a -/- mice lack the murine multiple drug resistance gene for P-glycoprotein 170 that is normally expressed in multiple tissues including intestinal epithelial cells. These mice spontaneously develop a form of colitis at around 12 wk of age. The fact that the complexity of this model mirrors the complexity of disease in humans, as well as recent literature that links MDR1 polymorphisms in humans to Crohn's Disease and Ulcerative Colitis, makes this an appropriate animal model to study.

GM-CSF treatment for Crohn's disease: a stimulating new therapy?

Crohn's disease (CD) has been classically viewed as an overactive intestinal immune response to the normal constituents of the gut flora. Most therapeutic strategies to date have tried to suppress this overactive adaptive immune response. Recently, a novel, rather alternative therapeutic strategy has been proposed, wherein the approach is to stimulate the innate immune system with growth factors. This review will take a closer look at this unconventional hypothesis and the data that support it, and will place the information in the context of some of the other biological and experimental therapies currently under consideration for the treatment of CD.