Polymorphous Low-Grade Neuroepithelial Tumor of the Young as a Partially Calcified Intra-Axial Mass in an Adult

Polymorphous low-grade neuroepithelial tumors of the young (PLNTYs) are recently described CNS tumors. Classically, PLNTYs are epileptogenic and are a subtype of a heterogeneous group of low-grade neuroepithelial tumors that cause refractory epilepsy, such as angiocentric gliomas, oligodendrogliomas, gangliogliomas, and pleomorphic xanthoastrocytomas. Although they are a relatively new entity, a number of imaging and histologic characteristics of PLNTYs are already known. We present the imaging and pathologic findings of such a tumor as well as the surgical approach and clinical management.

IKK-dependent, NF-κB-independent control of autophagic gene expression

The induction of mammalian autophagy, a cellular catabolic bulk-degradation process conserved from humans to yeast, was recently shown to require IκB kinase (IKK), the upstream regulator of the nuclear factor (NF)-κB pathway. Interestingly, it was shown that this response did not involve NF-κB. Thus, the mechanism by which IKK promotes stimulus-induced autophagy is largely unknown. Here, we investigate the role of IKK/NF-κB in response to nutrient deprivation, the well-understood autophagy-inducing stimulus. IKK and both the classic and non-canonical pathways of NF-κB are robustly induced in response to cellular starvation. Notably, cells lacking either catalytic subunit of IKK (IKK-α or IKK-β) fail to induce autophagy in response to cellular starvation. Importantly, we show that IKK activity but not NF-κB controls basal expression of the proautophagic gene LC3. We further demonstrate that starvation induces the expression of LC3 and two other essential autophagic genes ATG5 and Beclin-1 in an IKK-dependent manner. These results indicate that the IKK complex is a central mediator of starvation-induced autophagy in mammalian cells, and suggest that this requirement occurs at least in part through the regulation of autophagic gene expression. Interestingly, NF-κB subunits are dispensable for both basal and starvation-induced expression of proautophagic genes. However, starvation-induced activation of NF-κB is not inconsequential, as increases in expression of antiapoptotic NF-κB target genes such as Birc3 are observed in response to cellular starvation. Thus, IKK likely has multiple roles in response to starvation by regulating NF-κB-dependent antiapoptotic gene expression as well as controlling expression of autophagic genes through a yet undetermined mechanism.

Her2 activates NF-kappaB and induces invasion through the canonical pathway involving IKKalpha

The membrane bound receptor tyrosine kinase Her2 is overexpressed in approximately 30% of human breast cancers, which correlates with poor prognosis. Her2-induced signaling pathways include MAPK and PI3K/Akt, of which the latter has been shown to be critical for Her2(+) breast cancer cell growth and survival. In addition, the NF-kappaB pathway has been shown to be activated downstream of Her2 overexpression; however, the mechanisms leading to this activation are not currently clear. Using Her2(+)/ER(-) breast cancer cells, we show that Her2 activates NF-kappaB through the canonical pathway which, surprisingly, involves IKKalpha. Knockdown of IKKalpha led to a significant decrease in transcription levels of multiple NF-kappaB-regulated cytokine and chemokine genes. siRNA-mediated knockdown of IKKalpha resulted in a decrease in cancer cell invasion, but had no effect on cell proliferation. Inhibition of the PI3K/Akt pathway had no effect on NF-kappaB activation, but significantly inhibited cell proliferation. Our study suggests different roles for the NF-kappaB and PI3K pathways downstream of Her2, leading to changes in invasion and proliferation of breast cancer cells. In addition this work indicates the importance of IKKalpha as a mediator of Her2-induced tumor progression.

CCAAT box binding protein NF-Y facilitates in vivo recruitment of upstream DNA binding transcription factors

NF-Y binds a CCAAT motif found in many eukaryotic polymerase II-dependent promoters. In the HLA-DRA promoter it has been demonstrated that stereo-specific alignment between this motif and the upstream elements X1 and X2 is required for activation. To study the underlying mechanism for this requirement, a panel of transfected cell lines that maintained integrated, wild-type and mutant promoters were analyzed by in vivo genomic footprinting. Cell lines harboring a mutated CCAAT element exhibited a loss of interactions at the CCAAT site, as expected, and no transcriptional activity. Most importantly, mutation of the CCAAT sequence nearly abolished in vivo binding at the X1 and X2 sites, while mutations of X1 and X2 had little effect on CCAAT box binding. However, X1 and X2 binding was interdependent. In vitro, X1 binding activities are known to be stabilized by NF-Y binding. Interaction between NF-Y and X box binding proteins was demonstrated by reciprocal co-immunoprecipitation in the absence of DNA and co-affinity purification in the presence of DNA. Collectively, these studies indicate that occupancy of the CCAAT element represents an early event affecting other protein-DNA interactions and suggest that NF-Y stabilizes and interacts with X box factors to mediate this function. These findings may represent a common theme among promoters containing a CCAAT element.

Chromosomal localization of the genes encoding the p50/p105 subunits of NF-kappa B (NFKB2) and the I kappa B/MAD-3 (NFKBI) inhibitor of NF-kappa B to 4q24 and 14q13, respectively

The regulation of expression of a variety of genes involved in immune function, inflammation, and cellular growth control, as well as control of expression of certain viruses such as the human immunodeficiency virus (HIV), is dependent on the transcription factor NF-kappa B. In many cells, NF-kappa B is found in the cytoplasm where it is associated with an inhibitor protein known as I kappa B. Recently the genes encoding the p50 and p65 subunits of NF-kappa B, as well as one form of I kappa B/MAD-3 (NFKBI), have been cloned. As part of our goal to determine the chromosomal organization of members of the REL/NFKB family, as well as their inhibitors, we localized the NFKBp50/p105 (NFKB2) and I kappa B/MAD-3 (NFKBI) genes to human chromosome bands 4q24 and 14q13, respectively.