authors: Hu Z., Wang Y., Huang F., Chen R., Li C., Wang F., Goto J., Kwiatkowski DJ., Wdzieczak-Bakala J., Tu P., Liu J., Zha X., Zhang H.

J Biol Chem; 2015 Oct 16;290(42): 25756-65. doi: 10.1074/jbc.M115.665208.

Abstract

Frequent alteration of upstream proto-oncogenes and tumor suppressor genes activates mechanistictarget of rapamycin(mTOR) and causes cancer. However, the downstream effectors of mTOR remain largely elusive. Here we report that brain-expressedX-linked2 (BEX2) is a novel downstream effector of mTOR. Elevated BEX2 in Tsc2(-/-) mouse embryonic fibroblasts, Pten(-/-) mouse embryonic fibroblasts, Tsc2-deficient rat uterine leiomyoma cells, and brains of neuronal specific Tsc1 knock-out mice were abolished by mTOR inhibitor rapamycin. Furthermore, BEX2 was also increased in the liver of a hepatic specific Pten knock-out mouse and the kidneys of Tsc2 heterozygous deletion mice, and a patient with tuberous sclerosis complex (TSC). mTOR up-regulation of BEX2 was mediated in parallel by both STAT3 and NF-κB. BEX2 was involved in mTOR up-regulation of VEGF production and angiogenesis. Depletion of BEX2 blunted the tumorigenesis of cells with activated mTOR. Therefore, enhanced STAT3/NF-κB-BEX2-VEGF signaling pathway contributes to hyperactivemTOR-induced tumorigenesis. BEX2 may be targeted for the treatment of the cancers with aberrantly activated mTOR signaling pathway.

authors: Prabhakar S., Zhang X., Goto J., Han S., Lai C., Bronson R., Sena-Esteves M., Ramesh V., Stemmer-Rachamimov A., Kwiatkowski DJ., Breakefield XO.

Neurobiol Dis. 2015 Oct;82:22-31. doi: 10.1016/j.nbd.2015.04.018.

Abstract

We examined the potential benefit of genetherapy in a mousemodel of tuberoussclerosis complex (TSC) in which there is embryonic loss of Tsc1 (hamartin) in brain neurons. An adeno-associated virus (AAV) vector (serotype rh8) expressing a tagged form of hamartin was injected into the cerebral ventricles of newborn pups with the genotype Tsc1(cc) (homozygous for a conditional floxed Tsc1 allele) SynI-cre(+), in which Tsc1 is lost selectively in neurons starting at embryonic day 12. Vector-treated Tsc1(cc)SynIcre(+) mice showed a marked improvement in survival from a mean of 22 days in non-injected mice to 52 days in AAV hamartin vector-injected mice, with improved weight gain and motor behavior in the latter. Pathologic studies showed normalization of neuron size and a decrease in markers of mTOR activation in treated as compared to untreated mutant littermates. Hence, we show that gene replacement in the brain is an effective therapeutic approach in thismousemodel of TSC1. Our strategy for genetherapy has the advantages that therapy can be achieved from a single application, as compared to repeated treatment with drugs, and that AAV vectors have been found to have minimal to no toxicity in clinical trials for other neurologic conditions. Although there are many additional issues to be addressed, our studies support genetherapy as a useful approach in TSC patients.

authors: D'Gama AM., Geng Y., Couto JA., Martin B., Boyle EA., LaCoursiere CM., Hossain A., Hatem NE., Barry BJ., Kwiatkowski DJ., Vinters HV., Barkovich AJ., Shendure J., Mathern GW., Walsh GA., Poduri A.

Ann Neurol. 2015 Apr;77(4):720-5. doi: 10.1002/ana.24357.

Abstract

Focalmalformations of cortical development, including focalcortical dysplasia (FCD) and hemimegalencephaly (HME), are important causes of intractable childhood epilepsy. Using targeted and exome sequencing on DNA from resected brain samples and nonbrain samples from 53 patients with FCD or HME, we identified pathogenic germline and mosaic mutations in multiple PI3K/AKT pathway genes in 9 patients, and a likely pathogenic variant in 1 additional patient. Our data confirm the association of DEPDC5 with sporadic FCD but also implicate this gene for the first time in HME. Our findings suggest that modulation of the mammalian target of rapamycinpathway may hold promise for malformation-associated epilepsy.

authors: Leech JD., Lammers SH., Goldman S., Auricchio N., Bronson RT., Kwiatkowski D., Sahin M. 

Mol Cancer Res. 2015 Mar;13(3):548-55. doi: 10.1158/1541-7786.MCR-14-0178

Abstract

Tuberous sclerosis complex (TSC) is an autosomal disease caused by inactivating mutations in either of the tumorsuppressor genes TSC1 or TSC2. TSC-associated tumor growth is present in multiple tissues and organs including brain, kidney, liver, heart, lungs, and skin. In the kidney, TSC angiomyolipomas have aberrant vascular structures with abnormal endothelial cells, suggesting a role for endothelial mTORC1 function. In the current report, a genetically engineered mousemodel (GEMM) with a conditional knockout allele of Tsc1 with a Darpp32-Cre allele displayed accelerated formation of both kidney cystadenomas and paw hemangiosarcomas. All mutant mice developed hemangiosarcomas on multiple paws by 6 weeks of age. By 16 weeks of age, the average mutant hind paw was 4.0 mm in diameter, nearly double the size of control mice. Furthermore, the hemangiosarcomas and kidney cystadenomas were responsive to intraperitoneal rapamycin treatment. Immunoblotting and immunostaining for phospho-S6 (pS6) and phospho-CAD showed that the effect of rapamycin on tumor size was through inhibition of the mTOR signaling pathway. Finally, elevated VEGF mRNA levels were also observed in hemangiosarcoma specimens. Because paw hemangiosarcomas are easily detectable and scorable for size and growth, this novel mouse model enables accelerated in vivo drug testing for therapies of TSC-related tumors.

Implications: These findings provide a strong rationale for simultaneous use of this conditional knockout mouse as an in vivo genetic model while seeking new cancer therapies for TSC-related tumors. 

authors: Blümcke I., Aronica E., Miyata H., Sarnat HB., Thom M., Roessler K., Rydenhag B., Jehi L., Krsek P., Wiebe S., Spreafico R. 

Epilepsia. 2016 Mar;57(3): 348-58. doi: 10.1111/epi.13319

Abstract

Epilepsy surgery is an effective treatment in many patients with drug-resistant focal epilepsies. An early decision for surgical therapy is facilitated by a magnetic resonance imaging (MRI)-visible brain lesion congruent with the electrophysiologically abnormal brain region. Recent advances in the pathologic diagnosis and classification of epileptogenic brain lesions are helpful for clinical correlation, outcome stratification, and patient management. However, application of international consensus classification systems to common epileptic pathologies (e.g. focal cortical dysplasia (FCD) and hippocampal sclerosis (HS)) necessitates standardized protocols for neuropathologic workup op epilepsy surgery specimens. To this end, the Task Force of Neuropathology from the International League Against Epilepsy (ILAE) Commission on Diagnostic Methods developed a consensus standard operational procedure for tissue inspection, distribution and processing. The aims are to provide a systematic framework for histopathologic workup, meeting minimal standards and maximizing current and future opportunities for morphofunctional correlations and molecular studies for both clinical care and research. Whenever feasible, anatomically intact surgical specimens are desirable to enable systematic analysis in selective hippocampectomies, temporal lobe resections, and lesional or nonlesional neocortical samples. Correct orientation of sample and the sample's relation to neurophysiologically aberrant sites requires good communication between pathology and neurosurgical teams. Systematic tissue sampling of 5-mm slabs along a defined anatomic axis and application of a limited immunohistochemical panel will ensure a reliable differential diagnosis of main pathologies encountered in epilepsy surgery.