Cereblon-based Bifunctional Degrader of SOS1, BTX-6654, Targets Multiple KRAS Mutations and Inhibits Tumor Growth.

Mutations within the oncogene KRAS drive an estimated 25% of all cancers. Only allele-specific KRAS G12C inhibitors are currently available and are associated with the emergence of acquired resistance, partly due to upstream pathway reactivation. Given its upstream role in the activation of KRAS, son of sevenless homolog 1 (SOS1), has emerged as an attractive therapeutic target. Agents that target SOS1 for degradation could represent a potential pan-KRAS modality that may be capable of circumventing certain acquired resistance mechanisms. Here, we report the development of two SOS1 cereblon-based bifunctional degraders, BTX-6654 and BTX-7312, cereblon-based bifunctional SOS1 degraders. Both compounds exhibited potent target-dependent and -specific SOS1 degradation. BTX-6654 and BTX-7312 reduced downstream signaling markers, pERK and pS6, and displayed antiproliferative activity in cells harboring various KRAS mutations. In two KRAS G12C xenograft models, BTX-6654 degraded SOS1 in a dose-dependent manner correlating with tumor growth inhibition, additionally exhibiting synergy with KRAS and MEK inhibitors. Altogether, BTX-6654 provided preclinical proof of concept for single-agent and combination use of bifunctional SOS1 degraders in KRAS-driven cancers.

Molecular docking analysis of Omt-A protein model from Aspergillus flavus with synthetic compounds.

Aflatoxin is a potent mycotoxin of Aspergillus flavus that has been classified as a Group I carcinogen. O-methyltransferase A (Omt-A) is a critical enzyme in the formation of aflatoxin. It catalyzes the methylation of norsalic acid to form the highly toxic intermediate averantin. The ligand-protein interaction of Omt-A was performed with piperlonguminin and blasticidins. The maximum affinity of -10.6 was found for the 5ICC_A piperlonguminine at site1 (X,Y,Z: -15.282, 21.785, 5.672). Compounds such as Blasticidin S, Neoeriocitrin, Blasticidin S - hydrochloric acid, 6,6''-Bigenkwanin, Pipernomaline, and Eriodictyol were found to have binding features to protein residues, as shown by computational interaction at the molecular level.

False Positivity of rK39 Test in Five Chronic Myeloid Leukemia Cases from Bihar, India: A Possible Challenge to Leishmaniasis Diagnosis.

A rapid and noninvasive rK39 rapid diagnostic test (RDT) is the best and most reliable tool for visceral leishmaniasis (VL) screening in the field. However, splenic and bone marrow aspiration remain two gold standard methods for microscopic identification of Leishmania donovani (LD) bodies and confirmatory diagnosis of VL. Five patients with signs and symptoms of fever, loss of appetite, loss of weight, hepatomegaly, and massive splenomegaly were found to be false positive with the rK39 RDT. These patients were suspected to have chronic myeloid leukemia (CML) because their blood pictures showed a total white blood cell count of > 100,000/mm3 and abnormal cells such as stab, segmented promyelocytes, myelocytes, metamyelocytes, and blast cells. Splenic aspirate and bone marrow were negative for Leishmania donovani bodies. The bone marrow showed myeloid series of cells, that is, myelocytes, metamyelocytes, stab and segmented cells, blast cells, and markedly increased myeloid:erythroid ratio. Later, the CML diagnosis was confirmed in all cases by breakpoint cluster region-tyrosine protein kinase (BCR-ABL) gene positive test results. In this study, the rK39 RDT's false positivity was observed in CML cases. It could have important implications for the differential diagnosis of VL with CML. The rK39 positive test result in CML cases was a serendipitous occurrence; this should be validated further to determine the utility of the rK39 test in the differential diagnosis of VL with CML.

Hydrogen Peroxide Mediates Artemisinin-Derived C-16 Carba-Dimer-Induced Toxicity of Human Cancer Cells.

This study used a nitroaliphatic chemistry approach to synthesize a novel artemisinin-derived carba-dimer (AG-1) and determined its anti-proliferative effects in human normal and cancer cells. AG-1 treatments selectively inhibit proliferation of cancer cells compared to normal human fibroblasts. Compared to artemisinin, AG-1 is more toxic to human breast, prostate, head-neck, pancreas and skin cancer cells; 50% inhibition (IC50) 123 µM in AG-1 vs. 290 µM in artemisinin-treated breast cancer cells. AG-1 treatment decreased (~ 5 folds) cyclin D1 protein expression that correlated with an increase in the percentage of cells in the G1-phase, suggesting a G1 delay. AG-1-induced toxicity was independent of the DNA damage at 72 h post-treatment, as measured by micronuclei frequency and H2AX protein levels. Results from electron paramagnetic resonance spectroscopy showed Fe-catalyzed formation of AG-1 carbon-centered radicals in a cell-free system. Flow cytometry analysis of H2DCF-DA oxidation showed a significant increase in the steady-state levels of reactive oxygen species (ROS) in AG-1-treated cells. Pre-treatment with N-acetyl-l-cysteine and antioxidant enzymes (superoxide dismutase and catalase) significantly suppressed AG-1-induced toxicity, suggesting that superoxide and hydrogen peroxide contribute to AG-1-induced toxicity in human cancer cells. AG-1 represents a novel class of anti-cancer drug that is more potent than its parent compound, artemisinin.

Inertial Microfluidic Cell Stretcher (iMCS): Fully Automated, High-Throughput, and Near Real-Time Cell Mechanotyping.

Mechanical biomarkers associated with cytoskeletal structures have been reported as powerful label-free cell state identifiers. In order to measure cell mechanical properties, traditional biophysical (e.g., atomic force microscopy, micropipette aspiration, optical stretchers) and microfluidic approaches were mainly employed; however, they critically suffer from low-throughput, low-sensitivity, and/or time-consuming and labor-intensive processes, not allowing techniques to be practically used for cell biology research applications. Here, a novel inertial microfluidic cell stretcher (iMCS) capable of characterizing large populations of single-cell deformability near real-time is presented. The platform inertially controls cell positions in microchannels and deforms cells upon collision at a T-junction with large strain. The cell elongation motions are recorded, and thousands of cell deformability information is visualized near real-time similar to traditional flow cytometry. With a full automation, the entire cell mechanotyping process runs without any human intervention, realizing a user friendly and robust operation. Through iMCS, distinct cell stiffness changes in breast cancer progression and epithelial mesenchymal transition are reported, and the use of the platform for rapid cancer drug discovery is shown as well. The platform returns large populations of single-cell quantitative mechanical properties (e.g., shear modulus) on-the-fly with high statistical significances, enabling actual usages in clinical and biophysical studies.

Acute kidney injury in children after cardiopulmonary bypass: risk factors and outcome.

OBJECTIVE: To determine the incidence, risk factors and outcomes of acute kidney injury in children undergoing cardiac surgery for congenital heart disease. METHODS: We enrolled 208 patients undergoing cardiac surgery for congenital heart disease during January 2012 to March 2013. Acute kidney injury was defined as per Acute Kidney Injury Network criteria. RESULTS: Twenty patients had Acute kidney injury; 14 were infants. Age <1 yr, cardiopulmonary bypass time, prolonged ventilator requirement, pump failure, sepsis and hematological complications were identified as independent risk factors for any degree for acute kidney injury. All patients with acute kidney injury recovered the kidney function at the time of discharge. CONCLUSIONS: Acute kidney injury is common in children after cardiac surgery, especially in infants.

Vasoactive Inotrope Score as a tool for clinical care in children post cardiac surgery.

BACKGROUND: Neonates and infants undergoing heart surgery on cardiopulmonary bypass (CPB) are at high risk for significant post-operative morbidity and mortality. Hence, there is a need to identify and quantify clinical factors during the early post-operative period that are indicative of short-term as well as long-term outcomes. Multiple inotrope scores have been used in practice to quantify the amount of cardiovascular support received by neonates. AIMS: The goal of this study was to determine the association between inotropic/vasoactive support and clinical outcomes in children after open cardiac surgery. MATERIALS AND METHODS: This is a retrospective analysis of the 208 patients who underwent cardiac surgery for congenital heart disease at a tertiary pediatric cardiac surgery Intensive Care Unit (ICU) from January 2012 to March 2013. Multiple demographic, intra-operative and post-operative variables were recorded, including the Vasoactive Inotrope Score (VIS). RESULTS: A total of 208 patients underwent cardiac surgery for congenital heart disease in the study period. The mean age and weight in the study were 66.94 months and 16.31 kg, respectively. Statistically significant associations were found in the various variables and VIS, including infancy, weight < 10 kg, CPB time, pump failure and post-operative variables like sepsis, hematological complications, hepatic dysfunction, acute kidney injury during admission, mortality, prolonged ventilator requirement, CPB time (in min) and hospital stay. CONCLUSIONS: Inotrope score and its adaptations are an excellent tool to measure illness severity, deciding interventions and during parental counseling in the pediatric cardiac surgery ICUs.

Merosin-deficient congenital muscular dystrophy with cerebral white matter changes: a clue to its diagnosis beyond infancy.

A 6-year-old boy born by a third-degree consanguineous marriage presented with progressive muscle weakness and delayed motor milestones noticed in early infancy with preserved language and social milestones. Examination revealed generalised hypotonia and hyporeflexia. Baseline haematological and biochemical investigations were normal except for mildly elevated creatine kinase. Provisional diagnosis of congenital myopathy was entertained. We performed brain imaging to look for abnormalities associated with congenital muscular dystrophy even though there were only features of myopathy with normal mentation. An MRI of the brain revealed periventricular and subcortical white matter hyperintensities suggestive of leucoencephalopathy. Muscle biopsy findings were consistent with degenerative muscle changes and immunohistochemical staining for merosin was negative, thus confirming the diagnosis of merosin-deficient congenital muscular dystrophy. Supportive care in the form of physiotherapy was initiated. The family was offered genetic counselling in their second pregnancy and immunohistochemistry at 12 weeks confirmed the fetus to be affected, which was then terminated.

Engineered reversal of drug resistance in cancer cells--metastases suppressor factors as change agents.

Building molecular correlates of drug resistance in cancer and exploiting them for therapeutic intervention remains a pressing clinical need. To identify factors that impact drug resistance herein we built a model that couples inherent cell-based response toward drugs with transcriptomes of resistant/sensitive cells. To test this model, we focused on a group of genes called metastasis suppressor genes (MSGs) that influence aggressiveness and metastatic potential of cancers. Interestingly, modeling of 84 000 drug response transcriptome combinations predicted multiple MSGs to be associated with resistance of different cell types and drugs. As a case study, on inducing MSG levels in a drug resistant breast cancer line resistance to anticancer drugs caerulomycin, camptothecin and topotecan decreased by more than 50-60%, in both culture conditions and also in tumors generated in mice, in contrast to control un-induced cells. To our knowledge, this is the first demonstration of engineered reversal of drug resistance in cancer cells based on a model that exploits inherent cellular response profiles.

Reactive oxygen species mediate microRNA-302 regulation of AT-rich interacting domain 4a and C-C motif ligand 5 expression during transitions between quiescence and proliferation.

Normal cell growth consists of two distinct phases, quiescence and proliferation. Quiescence, or G(0), is a reversible growth arrest in which cells retain the ability to reenter the proliferative cycle (G(1), S, G(2), and M). Although not actively dividing, quiescent cells are metabolically active and quiescence is actively maintained. Our results from microRNA PCR arrays and Taqman PCR assays showed a significant decrease (4-fold) in miR-302 levels during quiescence compared to proliferating normal human fibroblasts, suggesting that miR-302 could regulate cellular proliferation. Results from a Q-RT-PCR and dual-luciferase-3'-UTR reporter assays identified ARID4a (AT-rich interacting domain 4a, also known as RBP1) and CCL5 (C-C motif ligand 5) as targets for miR-302. Ionizing radiation decreased miR-302 levels, which was associated with an increase in its target mRNA levels, ARID4a and CCL5. Such an inverse correlation was also observed in cells treated with hydrogen peroxide as well as SOD2-overexpressing cells. Overexpression of miR-302 suppresses ARID4a and CCL5 mRNA levels, and increased the percentage of S-phase cells. These results identified miR-302 as an ROS-sensitive regulator of ARID4a and CCL5 mRNAs as well as demonstrate a regulatory role of miR-302 during quiescence and proliferation.

MnSOD activity regulates hydroxytyrosol-induced extension of chronological lifespan.

Chronological lifespan (CLS) is defined as the duration of quiescence in which normal cells retain the capacity to reenter the proliferative cycle. This study investigates whether hydroxytyrosol (HT), a naturally occurring polyphenol found in olives, extends CLS in normal human fibroblasts (NHFs). Quiescent NHFs cultured for a long duration (30-60 days) lose their capacity to repopulate. Approximately 60% of these cells exit the cell cycle permanently; a significant increase in the doubling time of the cell population was observed. CLS was extended in quiescent NHFs that were cultured in the presence of HT for 30-60 days. HT-induced extension of CLS was associated with an approximately 3-fold increase in manganese superoxide dismutase (MnSOD) activity while there was no change in copper-zinc superoxide dismutase, catalase, or glutathione peroxidase protein levels. Quiescent NHFs overexpressing a dominant-negative mutant form of MnSOD failed to extend CLS. HT suppressed age-associated increase in mitochondrial ROS levels. Results from spectroscopy assays indicate that HT in the presence of peroxidases can undergo catechol-semiquinone-quinone redox cycling generating superoxide, which in a cellular context can activate the antioxidant system, e.g., MnSOD expression. These results demonstrate that HT extends CLS by increasing MnSOD activity and decreasing age-associated mitochondrial reactive oxygen species accumulation.

Redox control of the cell cycle in health and disease.

The cellular oxidation and reduction (redox) environment is influenced by the production and removal of reactive oxygen species (ROS). In recent years, several reports support the hypothesis that cellular ROS levels could function as ''second messengers'' regulating numerous cellular processes, including proliferation. Periodic oscillations in the cellular redox environment, a redox cycle, regulate cell-cycle progression from quiescence (G(0)) to proliferation (G(1), S, G(2), and M) and back to quiescence. A loss in the redox control of the cell cycle could lead to aberrant proliferation, a hallmark of various human pathologies. This review discusses the literature that supports the concept of a redox cycle controlling the mammalian cell cycle, with an emphasis on how this control relates to proliferative disorders including cancer, wound healing, fibrosis, cardiovascular diseases, diabetes, and neurodegenerative diseases. We hypothesize that reestablishing the redox control of the cell cycle by manipulating the cellular redox environment could improve many aspects of the proliferative disorders.

Late ROS accumulation and radiosensitivity in SOD1-overexpressing human glioma cells.

This study investigates the hypothesis that CuZn superoxide dismutase (SOD1) overexpression confers radioresistance to human glioma cells by regulating the late accumulation of reactive oxygen species (ROS) and the G(2)/M-checkpoint pathway. U118-9 human glioma cells (wild type, neo vector control, and stably overexpressing SOD1) were irradiated (0-10 Gy) and assayed for cell survival, cellular ROS levels, cell-cycle-phase distributions, and cyclin B1 expression. SOD1-overexpressing cells were radioresistant compared to wild-type (wt) and neo vector control (neo) cells. Irradiated wt and neo cells showed a significant increase (approximately twofold) in DHE fluorescence beginning at 2 days postirradiation, which remained elevated at 8 days postirradiation. Interestingly, the late accumulation of ROS was suppressed in irradiated SOD1-overexpressing cells. The increase in ROS levels was followed by a decrease in cell growth and viability and an increase in the percentage of cells with sub-G(1) DNA content. SOD1 overexpression enhanced radiation-induced G(2) accumulation within 24 h postirradiation, which was accompanied by a decrease in cyclin B1 mRNA and protein levels. These results support the hypothesis that long after radiation exposure a "metabolic redox response" regulates radiosensitivity of human glioma cells.

Retinal ganglion cell death and neuroprotection: Involvement of the CaMKIIalpha gene.

The purpose of this study is to determine if calcium/calmodulin-dependent protein kinase-II (CaMKII) plays a role in neuronal cell death and if inhibition of this kinase affords some neuroprotection in the RGC-5 retinal ganglion cell line. The RGC-5 cells were treated with glutamate at various concentrations for increasing increments of time. Cytotoxicity was assayed by measuring the lactate dehydrogenase (LDH) leakage from non-viable cells and TUNEL assays. The involvement of caspase-3, Bcl-2 and caspase-8 in glutamate-induced cytotoxicity was determined by immunoblots and/or real time RT-PCR. In addition, the autocamtide-2-related inhibitory peptide (AIP), a specific inhibitor of CaMKII, was used to determine the involvement of CaMKII in glutamate-induced RGC-5 cell death. Application of increasing concentrations of glutamate to RGC-5 cells caused a dose-dependent increase in the level of cell death after 24 h. There was a glutamate-stimulated increase in the expression of caspase-8 and caspase-3 and a corresponding decrease in Bcl-2. The active fragment of caspase-3 increased in glutamate-treated cells. An early transient increase in the expression of CaMKIIalpha(B) gene and a corresponding CaMKIIalpha nuclear translocation was found in glutamate-treated cells. Treatment with AIP blocked the activation of caspase-3 and protected RGC from glutamate-mediated cell death but did not alter the glutamate-enhanced expression levels of caspase-8 or caspase-3. This report shows the likely involvement of a transcript of the CaMKIIalpha gene in the cytotoxicity response of RGC-5 cells similar to previous reports in the neural retina. AIP is shown to be a neuroprotectant for RGC-5 cells as was reported for the neural retina.