CRK SH3N Domain Diminishes Cell Invasiveness of Non-Small Cell Lung Cancer.

CRK (c-Crk) as an adaptor protein is involved in several oncogenic signal transduction pathways, conveying oncogenic signals to its downstream effectors and thereby affecting multiple cellular processes including proliferation, differentiation, and migration. For example, we have observed that CRK expression and phosphorylation influence the invasiveness of non-small cell lung cancer (NSCLC) cells. To intervene in CRK signaling pathway, we examined whether CRK protein domains can be used as therapeutic tools to interrupt CRK signaling, thus influencing the biological behavior of NSCLC cells. For this purpose, Src Homology domains of CRK-I (i.e., SH2 and SH3N domains) were overexpressed in H157, Rh2, and A549 cells. CRK-SH3N domain expression induced epithelial morphology in H157 cells and enhanced epithelial morphology of A549 and Rh2 cells as compared to cells transfected with CRK-SH2 domain or empty vector. In addition, CRK-SH3N domain expression significantly decreased the motility and invasiveness of A549 and H157 cells. Furthermore, CRK-SH3N domain expression disrupted the interaction of CRK-II with DOCK180. In summary, these data provide evidence that the CRK-SH3N domain can be used to influence the malignant phenotype of NSCLC cells and also reduce the metastatic potential of these cells.

Exclusion of the uniform tetraploid cells significantly improves specificity of the urine FISH assay.

The urine fluorescence in situ hybridization (FISH) assay (UroVysion™), with the current scoring criteria, has a higher sensitivity than routine cytopathology but a lower specificity. Among 215 urine FISH tests we performed, 45 had associated histopathology and clinical follow up. In this study, a cell with four signals for each probe was classified as a uniform tetraploid cell (UTC); a presumed reparative cell which is currently classified as an abnormal cell in the FDA approved assay. By using the existing criteria, the tests were scored as positive or negative before and after exclusion of the UTCs. Before the exclusion, 24 positive, 13 negative, seven false positive, and one false negative result were obtained with 96% sensitivity and 65% specificity. After the exclusion, the results changed to 22 positive, 19 negative, one false positive, and three false negatives resulting in a 88% sensitivity of 88% and a 95% specificity; a significant improvement in the specificity. We conclude that exclusion of the UTCs as abnormal cells would result in a more solid performance of the FISH assay.

PAK1 kinase promotes cell motility and invasiveness through CRK-II serine phosphorylation in non-small cell lung cancer cells.

The role of c-Crk (CRK) in promoting metastasis is well described however the role of CRK phosphorylation and the corresponding signaling events are not well explained. We have observed CRK-II serine 41 phosphorylation is inversely correlated with p120-catenin and E-cadherin expressions in non-small cell lung cancer (NSCLC) cells. Therefore, we investigated the role of CRK-II serine 41 phosphorylation in the down-regulation of p120-catenin, cell motility and cell invasiveness in NSCLC cells. For this purpose, we expressed phosphomimetic and phosphodeficient CRK-II serine 41 mutants in NSCLC cells. NSCLC cells expressing phosphomimetic CRK-II seine 41 mutant showed lower p120-catenin level while CRK-II seine 41 phosphodeficient mutant expression resulted in higher p120-catenin. In addition, A549 cells expressing CRK-II serine 41 phosphomimetic mutant demonstrated more aggressive behavior in wound healing and invasion assays and, on the contrary, expression of phosphodeficient CRK-II serine 41 mutant in A549 cells resulted in reduced cell motility and invasiveness. We also provide evidence that PAK1 mediates CRK-II serine 41 phosphorylation. RNAi mediated silencing of PAK1 increased p120-catenin level in A549 and H157 cells. Furthermore, PAK1 silencing decreased cell motility and invasiveness in A549 cells. These effects were abrogated in A549 cells expressing phosphomimetic CRK-II serine 41. In summary, these data provide evidence for the role of PAK1 in the promotion of cell motility, cell invasiveness and the down regulation of p120-catenin through CRK serine 41 phosphorylation in NSCLC cells.

A novel role for Niemann-Pick disease type 2C protein in papillae formation.

BACKGROUND: Despite the presence of papillary structures and papillary tumors in humans, the mechanism of papillae formation is unknown. We describe herein a novel role for Niemann-Pick disease type 2C (NPC2) protein, a cholesterol binding protein in the lysosome, in papillae formation. METHODOLOGY/PRINCIPAL FINDING: We examined NPC2 protein expression in surgical samples of papillary tissues by immunohistochemical stain, and all papillary tissues expressed NPC2 protein in the epithelium. To examine our hypothesis of NPC2 protein-mediated papillae formation, we carried out xenograft experiments using wild H460 cells (large cell lung carcinoma cell line) that constitutively expressed abundant NPC2 protein and NPC2 protein-depleted H460 cells by NPC2 shRNA. The xenografts of wild H460 cells and empty shRNA vector cells showed distinct papillae formation, whereas NPC2 protein-depleted H460 cells displayed markedly reduced or no papillae. Since all papillary tissues have open spaces we examined whether NPC2 protein might also contribute to the creation of open spaces. The TUNEL assay in the xenografts of wild and empty shRNA vector H460 cells showed massive cell death, and NPC2 protein-depleted cells displayed minimal cell death. Measurement of caspase 3/7 activities in cultured H460 cells supported NPC2 protein-mediated apoptotic cell death. The presence of excess NPC2 protein, however, did not always produce papillae as seen in the xenografts of CHO cells that were stably transfected with NPC2. CONCLUSIONS/SIGNIFICANCE: The NPC2 protein of certain cells forms papillae coupled with apoptosis that creates open space. This protein may have future applications to modulate papillae formation and papillary growth in tumor tissues.

Indomethacin inhibits cell growth of medullary thyroid carcinoma by reducing cell cycle progression into S phase.

Indomethacin, a non-steroidal anti-inflammatory drug (NSAID), has been reported to inhibit the growth of medullary thyroid carcinoma (MTC) cells in vitro. However, the mechanism of inhibition of MTC cell growth by indomethacin and its potency have yet to be revealed. We examined the effect of indomethacin on three different MTC cell lines (TT cells, DRO 81-1 cells and HRO 85-1 cells) and two non-MTC cells. The mechanism of indomethacin action in MTC cells was investigated by analyzing intracellular prostaglandin level, apoptosis, and cell cycle in TT cells. Indomethacin inhibited cell growth of all three MTC cell lines but not normal thyroid cells or anaplastic thyroid carcinoma cells. Indomethacin at 10 microM or greater showed a dose response inhibition of cell growth. Indomethacin at 25 muM, a putative therapeutic serum indomethacin level, showed potency similar to 100 to 200 nM sunitinib, a receptor tyrosine kinase inhibitor. To examine whether prostaglandin depletion might determine the inhibition of MTC cell growth, we created different prostaglandin E2 (PGE2) levels in TT cells using three different NSAIDs. A profound PGE2 depletion by indomethacin-ester, a potent cyclooxygenase (COX) II inhibitor, showed the least inhibition of cell growth. Indomethacin did not increase apoptosis of TT cells. Indomethacin, but not naproxen or indomethacin-ester, reduced cell cycle progression into S phase; this was unrelated to the degree of PGE2 depletion. The expression of phosphorylated retinoblastoma (pRb) protein that shifts cells from G(1) to S phase was reduced after exposure to indomethacin. In conclusion, indomethacin has specific anti-tumor effect on MTC cells, probably by reducing cell cycle progression into S phase rather than by prostaglandin depletion. Since no drug therapy is currently available for MTC, indomethacin may be one of the therapeutic candidates.

A mutant thyroid hormone receptor alpha antagonizes peroxisome proliferator-activated receptor alpha signaling in vivo and impairs fatty acid oxidation.

Thyroid hormone regulates the balance between lipolysis and lipogenesis. We previously reported that male mice with a dominant-negative P398H mutation introduced into the TRalpha gene have visceral obesity, hyperleptinemia, and reduced catecholamine-stimulated lipolysis in white adipose tissue. Based on our observation of hepatic steatosis in the TRalpha P398H male mice, we used in vitro and in vivo models to investigate the influence of the TRalpha P398H mutant on peroxisome proliferator-activated receptor-alpha (PPARalpha) signaling. Wild-type TRalpha and the P398H mutant significantly reduced PPARalpha-mediated transcription in transient transfection assays. T(3) reversed the inhibition of PPARalpha action by wild-type TRalpha but not the P398H mutant. Chromatin immunoprecipitation assays demonstrated that the P398H mutant reduces PPARalpha binding to peroxisome proliferator receptor elements. In gel shift assays, the P398H mutant directly bound the peroxisome proliferator-activated receptor response element and inhibited PPARalpha binding, which was not reversed by addition of retinoid X receptor. The TRalpha R384C and PV dominant-negative mutants are not associated in vivo with a metabolic phenotype and had reduced (PV) or absent (R384C) PPARalpha inhibition compared with P398H. The metabolic phenotype of the P398H mutant mice is due, in part, to unique properties of the P398H mutant receptor interfering with PPARalpha signaling. The P398H mutant is a potential probe to characterize the physiological role of thyroid hormone receptor/PPARalpha interactions.

In vivo antitumor effects of the mTOR inhibitor CCI-779 against human multiple myeloma cells in a xenograft model.

In vitro studies indicate the therapeutic potential of mTOR inhibitors in treating multiple myeloma. To provide further support for this potential, we used the rapamycin analog CCI-779 in a myeloma xenograft model. CCI-779, given as 10 intraperitoneal injections, induced significant dose-dependent, antitumor responses against subcutaneous growth of 8226, OPM-2, and U266 cell lines. Effective doses of CCI-779 were associated with modest toxicity, inducing only transient thrombocytopenia and leukopenia. Immunohistochemical studies demonstrated the antitumor responses were associated with inhibited proliferation and angiogenesis, induction of apoptosis, and reduction in tumor cell size. Although CCI-779-mediated inhibition of the p70 mTOR substrate was equal in 8226 and OPM-2 tumor nodules, OPM-2 tumor growth was considerably more sensitive to inhibition of proliferation, angiogenesis, and induction of apoptosis. Furthermore, the OPM-2 tumors from treated mice were more likely to show down-regulated expression of cyclin D1 and c-myc and up-regulated p27 expression. Because earlier work suggested heightened AKT activity in OPM-2 tumors might induce hypersensitivity to mTOR inhibition, we directly tested this by stably transfecting a constitutively active AKT allele into U266 cells. The in vivo growth of the latter cells was remarkably more sensitive to CCI-779 than the growth of control U266 cells.

Systemic retinoic acid treatment induces sodium/iodide symporter expression and radioiodide uptake in mouse breast cancer models.

Lactating breast tissue and some breast cancers express the sodium/iodide symporter (NIS) and concentrate iodide. We recently demonstrated that all-trans retinoic acid (tRA) induces both NIS gene expression and iodide accumulation in vitro in well-differentiated human breast cancer cells (MCF-7). In the present study, we investigated the in vivo efficacy and specificity of tRA-stimulated iodide accumulation in mouse breast cancer models. Immunodeficient mice with MCF-7 xenograft tumors were treated with systemic tRA for 5 days. Iodide accumulation in the xenograft tumors was markedly increased, approximately 15-fold greater than levels without treatment, and the effects were tRA dose dependent. Iodide accumulation in other organs was not significantly influenced by tRA treatment. Significant induction of NIS mRNA and protein in the xenograft tumors was observed after tRA treatment. Iodide accumulation and NIS mRNA expression were also selectively induced in breast cancer tissues in transgenic mice expressing the oncogene, polyoma virus middle T antigen. These data demonstrate selective induction of functional NIS in breast cancer by tRA. Treatment with short-term systemic retinoic acid, followed by radioiodide administration, is a potential tool in the diagnosis and treatment of some differentiated breast cancer.

Enhanced expression of nicotinamide N-methyltransferase in human papillary thyroid carcinoma cells.

To gain an understanding of the molecular pathogenesis of thyroid cancer, we used DNA microarray to study the expression profiles of 10 different human thyroid carcinoma cell lines. These included papillary lines BHP 2-7, BHP 7-13, BHP 10-3, BHP 18-21, NPA 87, and TPC1; anaplastic lines ARO 81-1 and DRO 90-1; follicular line WRO 82-1; and medullary line HRO 85-1. Among the genes with increased expression in the cancer cell lines, a gene coding for nicotinamide N-methyltransferase (NNMT) was identified for being highly expressed only in the papillary cell lines. NNMT catalyzes N-methylation of nicotinamide and other structurally related compounds and is highly expressed in the human liver. The results were further confirmed by semiquantitative RT-PCR and Northern blot analysis. NNMT catalytic activities were determined in all of the cells described above and in additional cell lines. Significantly higher NNMT enzyme activities were detected in eight of 10 of the papillary lines and three of six of the follicular cell lines tested. Normal thyroid tissue, thyroid primary cultures, anaplastic cancer cells, and medullary cancer cells showed no or low enzyme activity. Immunohistochemical staining for NNMT of human thyroid specimens showed strong and abundant cytoplasmic reactions in the sections of papillary carcinomas, and weak or scanty reaction in the normal thyroid tissues. These results indicate that NNMT is a potential biomarker for papillary thyroid carcinoma.

Intestinal polyp formation in the Apcmin mouse: effects of levels of dietary calcium and altered vitamin D homeostasis.

This study evaluated the effects of various levels of dietary calcium on polyp formation, vitamin D homeostasis, and fecal bile acids in the Apcmin mouse. Female Apcmin mice were randomized to three groups and fed a purified diet with either half or double the level of calcium in control AIN-93G. Serum 25-OH-D and fecal bile acids were measured at weeks 0 and 12 of treatment. Mice were killed for polyp scoring by two observers blinded to treatment after 12 weeks. Results show there was no difference in polyp number or tumor load with dietary calcium in any treatment group. Serum 25-OH-D was reduced and total fecal bile acids were increased in animals that received the high calcium diet. We have previously shown that vitamin D supplementation diminishes polyp load; the lack of effect of an altered calcium diet seen here may be due to a disturbance in vitamin D homeostasis.

Two-dimensional complementary deoxyribonucleic acid electrophoresis revealing up-regulated human epididymal protein-1 and down-regulated CL-100 in thyroid papillary carcinoma.

Two-dimensional cDNA electrophoresis was used to analyze gene expressions in papillary carcinoma and normal tissue of thyroid glands. Pooled thyroid tissues were used to extract mRNA. Complementary DNAs, synthesized with NotI anchor primers, were digested with three restriction enzymes, NotI, EcoRV, and PvuII. The protruding NotI ends were filled in with (32)P deoxynucleotide triphosphates, and the radiolabeled cDNA fragments were separated in two dimensions. Approximately 500 cDNA fragments were visualized as discrete spots without probes. A total of 20 spots, 9 up-regulated and 11 down-regulated cDNAs in papillary carcinoma, were selected and cloned for sequencing. This experiment lent itself to a novel discovery of up-regulated human epididymal protein 1 (HE-1) and down-regulated CL-100 genes in thyroid papillary carcinomas confirmed by Northern blot analysis. Immunohistochemical stains showed abundant HE-1 protein in the papillary carcinoma, whereas little or no HE-1 protein was detected in other types of thyroid cancers and normal thyroid tissues. The restricted localization of HE-1 protein to the portions of papillary projections suggests an involvement of HE-1 protein for forming papillary shape. Our study showed that two-dimensional cDNA electrophoresis is a useful method of detecting differentially expressed genes in human diseases as demonstrated for HE-1 and CL-100 in papillary carcinoma.

Excessive survivin expression in thyroid lymphomas.

Thyroid lymphoma occurs most commonly in the thyroid glands with a background of Hashimoto's thyroiditis. Therefore, it is occasionally difficult to distinguish lymphoma from Hashimoto's thyroiditis because of some cellular and histologic similarities. We have examined whether survivin or human telomerase reverse transcriptase (hTERT) expression can differentiate between the 2 disorders. Surgically removed tissue samples from 6 patients with thyroid lymphoma and 6 patients with Hashimoto's thyroiditis were analyzed for mRNA levels of survivin and hTERT by real-time quantitative reverse-transcription polymerase chain reaction. Expression of survivin protein was examined by immunohistochemical stain using a polyclonal antibody. Survivin mRNA levels were greater in thyroid lymphoma than in Hashimoto's thyroiditis: 49.1 +/-36.4 versus 6.6 +/-2.7 pg/ng rRNA (mean +/- SD) (P <0.005). Immunohistochemical stain confirmed an abundance of survivin protein in lymphoid cells of thyroid lymphoma. The amount of hTERT mRNA did not differ in the 2 disorders. Our study shows that measuring survivin mRNA levels or immunohistochemistry of the protein expression can be useful to aid the diagnosis of thyroid lymphoma when histologic diagnosis is difficult.