Casein kinase 2α regulates glioblastoma brain tumor-initiating cell growth through the ß-catenin pathway.

Glioblastoma (GBM) is the most common and fatal primary brain tumor in humans, and it is essential that new and better therapies are developed to treat this disease. Previous research suggests that casein kinase 2 (CK2) may be a promising therapeutic target for GBMs. CK2 has enhanced expression or activity in numerous cancers, including GBM, and it has been demonstrated that inhibitors of CK2 regressed tumor growth in GBM xenograft mouse models. Our studies demonstrate that the CK2 subunit, CK2α, is overexpressed in and has an important role in regulating brain tumor-initiating cells (BTIC) in GBM. Initial studies showed that two GBM cell lines (U87-MG and U138) transduced with CK2α had enhanced proliferation and anchorage-independent growth. Inhibition of CKα using siRNA or small-molecule inhibitors (TBBz, CX-4945) reduced cell growth, decreased tumor size, and increased survival rates in GBM xenograft mouse models. We also verified that inhibition of CK2α decreased the activity of a well-known GBM-initiating cell regulator, ß-catenin. Loss of CK2α decreased two ß-catenin-regulated genes that are involved in GBM-initiating cell growth, OCT4 and NANOG. To determine the importance of CK2α in GBM stem cell maintenance, we reduced CK2α activity in primary GBM samples and tumor spheres derived from GBM patients. We discovered that loss of CK2α activity reduced the sphere-forming capacity of BTIC and decreased numerous GBM stem cell markers, including CD133, CD90, CD49f and A2B5. Our study suggests that CK2α is involved in GBM tumorigenesis by maintaining BTIC through the regulation of ß-catenin.

The role of the c-Jun N-terminal kinase 2-α-isoform in non-small cell lung carcinoma tumorigenesis.

The c-Jun N-terminal kinases (JNKs) are members of the mitogen-activated protein kinase family and have been implicated in tumorigenesis. One isoform in particular, JNK2α, has been shown to be frequently activated in primary brain tumors, to enhance several tumorigenic phenotypes and to increase tumor formation in mice. As JNK is frequently activated in non-small cell lung carcinoma (NSCLC), we investigated the role of the JNK2α isoform in NSCLC formation by examining its expression in primary tumors and by modulating its expression in cultured cell lines. We discovered that 60% of the tested primary NSCLC tumors had three-fold higher JNK2 protein and two- to three-fold higher JNK2α mRNA expression than normal lung control tissue. To determine the importance of JNK2α in NSCLC progression, we reduced JNK2α expression in multiple NSCLC cell lines using short hairpin RNA. Cell lines deficient in JNK2α had decreased cellular growth and anchorage-independent growth, and the tumors were four-fold smaller in mass. To elucidate the mechanism by which JNK2α induces NSCLC growth, we analyzed the JNK substrate, signal transducer and activator of transcription 3 (STAT3). Our data demonstrates for the first time that JNK2α can regulate the transcriptional activity of STAT3 by phosphorylating the Ser727 residue, thereby regulating the expression of oncogenic genes, such as c-Myc. Furthermore, reintroduction of JNK2α2 or STAT3 restored the tumorigenicity of the NSCLC cells, demonstrating that JNK2α is important for NSCLC progression. Our studies reveal a novel mechanism in which phosphorylation of STAT3 is mediated by a constitutively active JNK2 isoform, JNK2α.

Effects of the type of dietary fat at two levels of vitamin E in Wistar male rats during development and aging. III. Biochemical and morphometric parameters of the liver.

The purpose of this study was to explore in rats the possible influence of the type of dietary fat at two extreme levels of vitamin E on several biochemically determined hepatic changes and on a number of quantitatively analyzed structural and ultrastructural variations with age in hepatic cells. Six groups of weanling Wistar male rats were fed ad libitum isoenergetic diets containing similar amounts (15 g per 100 g diet) of saturated fat (coconut oil), unsaturated fat (safflower oil) or a combination of both at two levels of dl-alpha-tocopherol (2 or 200 mg per 100 g of diet). Determinations were performed in rats killed at 3, 6, 12, 18 and 24 months. Although in relation to age and irrespective of the type of diet, several of the biochemical parameters fluctuated with time, comparisons of the results between the youngest and oldest rats showed no changes in the levels of hepatic RNA, phospholipids, cholesterol, total tocopherols and total collagens, significant increases in DNA and triglycerides and a significant decrease in total protein. While the type of diet did not have in general significant influences on the levels of DNA, RNA, total protein and collagens, either the type of dietary fat and/or the levels of vitamin E had some definite effects on the levels of triglycerides, cholesterol, phospholipids and total tocopherols, as well as on the in vitro formation of malonaldehyde and on the eventual occurrence of in vivo lipoperoxidation (diene conjugation). These effects, however, varied in relation to the duration of the diverse dietary treatments. The morphologic studies indicated that all the livers had variable but generally moderate degrees of fatty changes (mainly due to triglyceride accumulation) which were attributed to the moderate obesity found in the rats. The mean nuclear and cell dimensions of hepatocytes, the number of binucleated hepatocytes, surface density of rough endoplasmic reticulum, numerical density of mitochondria and the fractional cytoplasmic volume occupied by lipofuscin pigment in hepatocytes were not significantly affected by the type of diet, by age or by the eventual occurrence of in vivo hepatic lipoperoxidation, whereas the numerical density of hepatocytes (mono- and binucleated) and "litoral cells" (endothelial, Kupffer and Ito cells), although unaffected by diet, significantly increased with age. On the other hand, the fractional volume of mitochondria and peroxisomes, as well as the numerical density of peroxisomes, were significantly influenced by the type of dietary fat and to lesser extent by the dietary levels of vitamin E.

Effects of the type of dietary fat at two levels of vitamin E in Wistar male rats during development and aging. I. Life span, serum biochemical parameters and pathological changes.

This experiment was designed to study in rats the implications of the dietary type of fat at two levels of vitamin E on the life span as well as on several biochemical and anatomopathological age-related changes. For this purpose, six different isoenergetic diets containing 15% coconut oil (SFD), safflower oil (UFD) or a combination of both (CFD) with 2 or 200 mg% of dl-alpha-tocopherol were offered ad libitum to outbred Wistar male rats from weaning to senescence. The results indicated that up to 9--12 months the body weights of rats consuming the CFD or the UFD increased generally faster than those fed the SFD, and that all rats developed moderate degrees of obesity. Age-dependent changes in organ weights (kidneys, testes, spleen, brain, liver and heart) were unaffected by diet. Serum levels of vitamin E generally reflected the corresponding dietary levels, but were also influenced by the type of dietary fat. Serum cholesterol levels were not significantly affected by the type of diet or by age. Only transient hypotriglyceridemic and hypophospholipidemic effects of the UFD were observed and, while the levels of triglycerides decreased with age up to the 18th month followed by an increase at 24 months, the levels of serum phospholipids remained unchanged. Neither diet nor age modified the serum albumin/globulin ratios. While no differences in maximum life span were found between dietary groups, the 50% survival time of rats fed the UFD at high level of vitamin E was significantly longer than in all the other groups. This beneficial effect was related to postponement of the onset and reduction of incidence of malignant neoplasms, but was apparently not related to any particular influence on the incidence or severity of chronic nephropathy which practically developed in all rats. Various neoplastic, degenerative and inflammatory diseases encountered in rats dying during the course of the experiment were tabulated and compared with similar findings reported by others in different strains of rats. Pituitary and adrenocortical adenomas as well as adrenocortical and renal carcinomas were the most frequent tumors found in this study. All the pathological changes provided useful baseline information for the evaluation of data presented in this and subsequent communications of this series of studies.