Mark A Nelson

Publications of Mark A Nelson

• MicroRNA-101 (miR-101) post-transcriptionally regulates the expression of EP4 receptor in colon cancers.

  Authors: Anupama Chandramouli, Benjamin Chidi Onyeagucha, Melania E Mercado-Pimentel, Lenka Stankova, Nisreen Abu Shahin, Bonnie J LaFleur, Ronald L Heimark, Achyut K Bhattacharyya, Mark A Nelson

  Cancer biology & therapy. 02/2012; 13(3):175-83.

  Expression of the PGE2 receptor, EP4, is up-regulated during colorectal carcinogenesis. However the mechanism leading to deregulation of the EP4 receptor is not known. The present study was conductedExpression of the PGE2 receptor, EP4, is up-regulated during colorectal carcinogenesis. However the mechanism leading to deregulation of the EP4 receptor is not known. The present study was conducted to investigate the regulation of EP4 receptor by miRNAs. We analyzed 26 colon cancers (i.e. 15 adenocarcinomas and 9 adenomas) and 16 normal colon specimens for EP4 receptor expression by immunohistochemistry. A bioinformatics approached identified putative microRNA binding sites with the 3'-UTR of the EP4 receptor. Both colon cancer cell lines and tumor specimens were analyzed for miR-101 and EP4 expression by qRT-PCR and Western analysis respectively and simultaneously in situ hybridizations was used to confirm our results. In vitro and in vivo assays were used to confirm our clinical findings. We observed an inverse correlation between the levels of miR-101 and EP4 receptor protein. Transfection of LS174T cells with miR-101 significantly suppressed a luciferase reporter containing the EP4 receptor-3'-UTR. In contrast, a mutant EP4 receptor-3'-UTR construct was unaffected. Ectopic expression of miR-101 markedly reduced cell proliferation and motility. Co-transfection of EP4 receptor could rescue colon cancer cells from the tumor suppressive effects of miR-101. Moreover, the pharmacologic inhibition of EP4 receptor signaling or silencing of EP4 receptor phenocopied the effect of miR-101. This is the first study to show that the EP4 receptor is negatively regulated by miR-101. These data provide new insights in the modulation of EP-4 receptor expression at the post-transcriptional level by miR-101 and suggests therapeutic strategies against miR-101 targets may be warranted.

• Inhibition of p38-MAPK signaling pathway attenuates breast cancer induced bone pain and disease progression in a murine model of cancer-induced bone pain.

  Authors: Devki Sukhtankar, Alec Okun, Anupama Chandramouli, Mark A Nelson, Todd W Vanderah, Anne E Cress, Frank Porreca, Tamara King

  Molecular pain. 01/2011; 7:81.

  Mechanisms driving cancer-induced bone pain are poorly understood. A central factor implicated to be a key player in the process of tumorigenesis, osteoclastogenesis and nociception is p38 MAPK. WeMechanisms driving cancer-induced bone pain are poorly understood. A central factor implicated to be a key player in the process of tumorigenesis, osteoclastogenesis and nociception is p38 MAPK. We determined the role of p38 MAPK in a mouse model of breast cancer induced bone pain in which mixed osteolytic and osteoblastic remodeling occurs. In cancer-treated mice, acute as well as chronic inhibition of p38 MAPK with SB203580 blocked flinching and guarding behaviors in a dose-dependent manner whereas no effect on thresholds to tactile stimuli was observed. Radiographic analyses of bones demonstrated that chronic inhibition of p38 MAPK reduced bone loss and incidence of spontaneous fracture in cancer-treated mice. Histological analysis of bones collected from mice treated with the p38 MAPK inhibitor showed complete absence of osteoblastic growth in the intramedullary space as well as significantly reduced tumor burden. Blockade of non-evoked pain behaviors but not hypersensitivity suggests differences in the underlying mechanisms of specific components of the pain syndrome and a possibility to individualize aspects of pain management. While it is not known whether the role of p38 MAPK signaling can be expanded to other cancers, the data suggest a need for understanding molecular mechanisms and cellular events that initiate and maintain cancer-induced bone pain for effective management for both ongoing pain as well as breakthrough pain.

• The induction of S100p expression by the Prostaglandin E₂ (PGE₂)/EP4 receptor signaling pathway in colon cancer cells.

  Authors: Anupama Chandramouli, Melania E Mercado-Pimentel, Anthony Hutchinson, Adriana Gibadulinová, Erik R Olson, Sally Dickinson, Reneé Shañas, Jennifer Davenport, Janae Owens, Achyut K Bhattacharyya, John W Regan, Silvia Pastorekova, Thiruvengadam Arumugam, Craig D Logsdon, Mark A Nelson

  Cancer biology & therapy. 11/2010; 10(10):1056-66.

  BACKGROUND: Prostaglandin E₂ (PGE₂) levels are frequently elevated in colorectal carcinomas. PGE₂ is perceived via four transmembrane G protein coupled receptors (EP1-4), among which the EP4 receptorBACKGROUND: Prostaglandin E₂ (PGE₂) levels are frequently elevated in colorectal carcinomas. PGE₂ is perceived via four transmembrane G protein coupled receptors (EP1-4), among which the EP4 receptor is most relevant. PGE₂/EP4-receptor interaction activates CREB via the ERK/MEK pathway. However, the downstream target genes activated by this pathway remained to be investigated. METHODOLOGY/PRINICIPAL FINDINGS: Here, we have identified S100P (an EF-hand calcium binding protein) as a novel downstream target. We show by realtime RT-PCR that S100P mRNA levels are elevated in 14/17 (82%) colon tumor tissues as compared to paired adjacent normal colonic tissues. S100P expression is stimulated in the presence of PGE₂ in a time dependent manner at mRNA and protein levels in colon, breast and pancreatic cancer cells. Pharmacological and RNAi-mediated inhibition of the EP4 receptor attenuates PGE₂-dependent S100P mRNA induction. RNA(i)-mediated knockdown of CREB inhibits endogenous S100P expression. Furthermore, using luciferase reporter analysis and EMSA we show that mutation and/or deletion of the CRE sequence within the S100P promoter abolished PGE₂-mediated transcriptional induction. Finally, we demonstrate that RNA(i)-mediated knockdown of S100P compromised invadopodia formation, colony growth and motility of colon cancer cells. Interestingly, endogenous knock down of S100P decreases ERK expression levels, suggesting a role for ERK in regulating S100P mediated cell growth and motility. CONCLUSIONS/SIGNIFICANCE: Together, our findings show for the first time that S100P expression is regulated by PGE₂/EP4-receptor signaling and may participate in a feedback signaling that perpetuates tumor cell growth and migration. Therefore, our data suggest that dysregulated S100P expression resulting from aberrant PGE₂/EP4 receptor signaling may have important consequences relevant to colon cancer pathogenesis.

• Increased expression of the heterogeneous nuclear ribonucleoprotein K in pancreatic cancer and its association with the mutant p53.

  Authors: Renyuan Zhou, Reneé Shanas, Mark A Nelson, Achyut Bhattacharyya, Jiaqi Shi

  International journal of cancer. Journal international du cancer. 08/2009;

  The heterogeneous nuclear ribonucleoprotein (hnRNP) K is an essential RNA and DNA binding protein involved in gene expression and signal transduction including DNA transcription, RNA splicing, RNAThe heterogeneous nuclear ribonucleoprotein (hnRNP) K is an essential RNA and DNA binding protein involved in gene expression and signal transduction including DNA transcription, RNA splicing, RNA stability, and translation. The role of hnRNP K in cancer is relatively understudied. However, several cellular functions strongly indicate that hnRNP K is involved in tumorigenesis. In the present study, we investigated the altered protein expression and the subcellular distribution of the hnRNP K protein using tissue microarrays in pancreatic cancer. We showed an increased cytoplasmic hnRNP K in pancreatic cancer. This increase in hnRNP K protein occurs at the posttranscriptional level. We postulate that the cytoplasmic accumulation of hnRNP K will lead to silenced mRNA translation of tumor suppressor genes and thus contributes to pancreatic cancer development. We also demonstrated that knocking down of hnRNP K expression by siRNA inhibited pancreatic cancer cell growth and colony formation. hnRNP K was identified as a member of the p53/HDM2 pathway. Whether hnRNP K interacts with the mutant p53 is not known. Using two different pancreatic cancer cell lines, we can demonstrate that hnRNP K interacts with the mutant p53. The subcellular distribution and function of the mutant p53 and the interaction of hnRNP K/mutant p53 were affected by the Ras/MEK/ERK pathway, growth factors and the specific p53 mutations in pancreatic cancer cells. Since Kras is activated and p53 is mutated in most pancreatic cancers, these data unveiled an important new signaling pathway that linked by hnRNP K and mutant p53 in pancreatic cancer tumorigenesis. (c) 2009 UICC.

• A multicenter, double-blinded validation study of methylation biomarkers for progression prediction in Barrett's esophagus.

  Authors: Zhe Jin, Yulan Cheng, Wen Gu, Yingye Zheng, Fumiaki Sato, Yuriko Mori, Alexandru V Olaru, Bogdan C Paun, Jian Yang, Takatsugu Kan [......] Jean Wang, Marcia Irene Canto, Achyut Bhattacharyya, Mark A Nelson, Paul D Wagner, Yvonne Romero, Kenneth K Wang, Ziding Feng, Richard E Sampliner, Stephen J Meltzer

  Cancer research. 05/2009; 69(10):4112-5.

  Esophageal adenocarcinoma risk in Barrett's esophagus (BE) is increased 30- to 125-fold versus the general population. Among all BE patients, however, neoplastic progression occurs only once per 200Esophageal adenocarcinoma risk in Barrett's esophagus (BE) is increased 30- to 125-fold versus the general population. Among all BE patients, however, neoplastic progression occurs only once per 200 patient-years. Molecular biomarkers are therefore needed to risk-stratify patients for more efficient surveillance endoscopy and to improve the early detection of progression. We therefore performed a retrospective, multicenter, double-blinded validation study of eight BE progression prediction methylation biomarkers. Progression or nonprogression were determined at 2 years (tier 1) and 4 years (tier 2). Methylation was assayed in 145 nonprogressors and 50 progressors using real-time quantitative methylation-specific PCR. Progressors were significantly older than nonprogressors (70.6 versus 62.5 years; P < 0.001). We evaluated a linear combination of the eight markers, using coefficients from a multivariate logistic regression analysis. Areas under the ROC curve (AUC) were high in the 2-year, 4-year, and combined data models (0.843, 0.829, and 0.840; P < 0.001, <0.001, and <0.001, respectively). In addition, even after rigorous overfitting correction, the incremental AUCs contributed by panels based on the 8 markers plus age versus age alone were substantial (Delta-AUC = 0.152, 0.114, and 0.118, respectively) in all 3 models. A methylation biomarker-based panel to predict neoplastic progression in BE has potential clinical value in improving both the efficiency of surveillance endoscopy and the early detection of neoplasia.

• "Phosphorylation of the eukaryotic initiation factor 3f by cyclin dependent kinase 11 during apoptosis"

  Authors: Jiaqi Shi, John W B Hershey, Mark A Nelson

  FEBS letters. 03/2009;

  eIF3f is a subunit of eIF3. We previously showed that eIF3f is phosphorylated by CDK11(p46) which is an important effector in apoptosis. Here, we identified a second eIF3f phosphorylation siteeIF3f is a subunit of eIF3. We previously showed that eIF3f is phosphorylated by CDK11(p46) which is an important effector in apoptosis. Here, we identified a second eIF3f phosphorylation site (Thr119) by CDK11(p46) during apoptosis. We demonstrated that eIF3f is directly phosphorylated by CDK11(p46)in vivo. Phosphorylation of eIF3f plays an important role in regulating its function in translation and apoptosis. Phosphorylation of eIF3f enhances the association of eIF3f with the core eIF3 subunits during apoptosis. Our data suggested that eIF3f may inhibit translation by increasing the binding to the eIF3 complex during apoptosis.

• Loss of the eukaryotic initiation factor 3f in pancreatic cancer.

  Authors: Adriana Doldan, Anupama Chandramouli, Reneé Shanas, Achyut Bhattacharyya, John T Cunningham, Mark A Nelson, Jiaqi Shi

  Molecular carcinogenesis. 04/2008; 47(3):235-44.

  Aberrant regulation of the translation initiation is known to contribute to tumorigenesis. eIF3 plays an important role in translation initiation. eIF3f is the p47 subunit of the eIF3 complex whoseAberrant regulation of the translation initiation is known to contribute to tumorigenesis. eIF3 plays an important role in translation initiation. eIF3f is the p47 subunit of the eIF3 complex whose function in cancer is not clear. Initial studies from our group indicated that eIF3f expression is decreased in pancreatic cancer. Overexpression of eIF3f induces apoptosis in pancreatic cancer cells. The eIF3f gene is located at chromosome band region 11p15.4. Loss of 11p15.4 is a common event in many tumors including pancreatic cancer. In order to investigate the molecular mechanism of the decreased expression of eIF3f in pancreatic cancer, we performed loss of heterozygosity (LOH) analysis in 32 pancreatic cancer specimens using three microsatellite markers encompassing the eIF3f gene. We showed that the prevalence of LOH ranged from 71% to 93%. We also performed eIF3f gene copy number analysis using quantitative real time PCR to further confirm the specific allelic loss of eIF3f gene in pancreatic cancer. We demonstrated a statistically significant decrease of eIF3f gene copy number in pancreatic tumors compared with normal tissues with a tumor/normal ratio of 0.24. Furthermore, RNA in situ hybridization and tissue microarray immunohistochemistry analysis demonstrated that eIF3f expression is significantly decreased in human pancreatic adenocarcinoma tissues compared to normal pancreatic tissues. These data provides new insight into the understanding of the molecular pathogenesis of eIF3f during pancreatic tumorigenesis.

• Loss of the eukaryotic initiation factor 3f in melanoma.

  Authors: Adriana Doldan, Anupama Chandramouli, Reneé Shanas, Achyut Bhattacharyya, Stanley P L Leong, Mark A Nelson, Jiaqi Shi

  Molecular carcinogenesis. 04/2008;

  Aberrant regulation of the translation initiation is known to contribute to tumorigenesis. eIF3 plays an important role in translation initiation. eIF3f is the p47 subunit of the eIF3 complex whoseAberrant regulation of the translation initiation is known to contribute to tumorigenesis. eIF3 plays an important role in translation initiation. eIF3f is the p47 subunit of the eIF3 complex whose function in cancer is not clear. Initial studies from our group indicated that eIF3f expression is decreased in melanoma. Overexpression of eIF3f inhibits translation and induces apoptosis in melanoma cells. The eIF3f gene is located at chromosome region 11p15.4. Loss of 11p15.4 is a common event in many tumors including melanoma. In order to investigate the molecular mechanism of the decreased expression of eIF3f in melanoma, we performed loss of heterozygosity (LOH) analysis in 24 melanoma specimens using three microsatellite markers encompassing the eIF3f gene. We showed that the prevalence of LOH ranged from 75% to 92% in melanoma. We also performed eIF3f gene copy number analysis using quantitative real-time PCR to further confirm the specific allelic loss of the eIF3f gene in melanoma. We demonstrated a statistically significant decrease of the eIF3f gene copy number in melanoma compared with normal tissues with a tumor/normal ratio of 0.52. To further elucidate the somatic genetic alterations, we carried out mutation analysis covering the entire coding region and 5'UTR of the eIF3f gene in melanoma tissues and cell lines. Despite some polymorphisms, we did not find any mutations. Furthermore, immunohistochemistry analysis demonstrated that eIF3f protein expression is decreased in melanoma compared to benign nevi. These data provide new insight into the understanding of the molecular pathogenesis of eIF3f during melanoma tumorigenesis. (c) 2008 Wiley-Liss, Inc.

• Identification of Fn14/TWEAK receptor as a potential therapeutic target in esophageal adenocarcinoma.

  Authors: George S Watts, Nhan L Tran, Michael E Berens, Achyut K Bhattacharyya, Mark A Nelson, Elizabeth A Montgomery, Richard E Sampliner

  International journal of cancer. Journal international du cancer. 12/2007; 121(10):2132-9.

  Given the poor survival rate and efficacy of current therapy for esophageal adenocarcinoma (EAC), there is a need to identify and develop new therapeutic targets for treatment. Microarray analysisGiven the poor survival rate and efficacy of current therapy for esophageal adenocarcinoma (EAC), there is a need to identify and develop new therapeutic targets for treatment. Microarray analysis (Affymetrix U133A GeneChips, Robust Multi-Chip Analysis) was used to expression profile 11 normal squamous and 18 Barrett's esophagus biopsies, 7 surgically resected EACs and 3 EAC cell lines. Two hundred transcripts representing potential therapeutic targets were identified using the following criteria: significant overexpression in EAC by analysis of variance (p = 0.05, Benjamini Hochberg false discovery rate); 3-fold increase in EAC relative to normal and Barrett's esophagus and expression in at least 2 of the 3 EAC cell lines. From the list of potential targets we selected TNFRSF12A/Fn14/TWEAK receptor, a tumor necrosis factor super-family receptor, for further validation based on its reported role in tumor cell survival and potential as a target for therapy. Fn14 protein expression was confirmed in SEG-1 and BIC-1 cell lines, but Fn14 was not found to affect tumor cell survival after exposure to chemotherapeutics as expected. Instead, a novel role in EAC was discovered in transwell assays, in which modulating Fn14 expression affected tumor cell invasion. Fn14's potential as a therapeutic target was further supported by immunohistochemistry on a tissue microarray of patient samples that showed that Fn14 protein expression increased with disease progression in EAC.

• The EP4 receptor antagonist, L-161,982, blocks prostaglandin E2-induced signal transduction and cell proliferation in HCA-7 colon cancer cells.

  Authors: Durga Prasad Cherukuri, Xiao B O Chen, Anne-Christine Goulet, Robert N Young, Yongxin Han, Ronald L Heimark, John W Regan, Emmanuelle Meuillet, Mark A Nelson

  Experimental cell research. 09/2007; 313(14):2969-79.

  Accumulating evidence indicates that elevated levels of prostaglandin E(2) (PGE(2)) can increase intestinal epithelial cell proliferation, and thus play a role in colorectal tumorigenesis. PGE(2)Accumulating evidence indicates that elevated levels of prostaglandin E(2) (PGE(2)) can increase intestinal epithelial cell proliferation, and thus play a role in colorectal tumorigenesis. PGE(2) exerts its effects through four G-protein-coupled PGE receptor (EP) subtypes, named the EP1, EP2, EP3, and EP4. Increased phosphorylation of extracellular regulated kinases (ERK1/2) is required for PGE(2) to stimulate cell proliferation of human colon cancer cells. However, the EP receptor(s) that are involved in this process remain unknown. We provide evidence that L-161,982, a selective EP4 receptor antagonist, completely blocks PGE(2)-induced ERK phosphorylation and cell proliferation of HCA-7 cells. In order to identify downstream target genes of ERK1/2 signaling, we found that PGE(2) induces expression of early growth response gene-1 (EGR-1) downstream of ERK1/2 and regulates its expression at the level of transcription. PGE(2) treatment induces phosphorylation of cyclic AMP response element binding protein (CREB) at Ser133 residue and CRE-mediated luciferase activity in HCA-7 cells. Studies with dominant-negative CREB mutant (ACREB) provide clear evidence for the involvement of CREB in PGE(2) driven egr-1 transcription in HCA-7 cells. In conclusion, this study reveals that egr-1 is a target gene of PGE(2) in HCA-7 cells and is regulated via the newly identified EP4/ERK/CREB pathway. Finally our results support the notion that antagonizing EP4 receptors may provide a novel therapeutic approach to the treatment of colon cancer.

• Haploinsufficiency of the cdc2l gene contributes to skin cancer development in mice.

  Authors: Anupama Chandramouli, Jiaqi Shi, Yongmei Feng, Hana Holubec, Renée M Shanas, Achyut K Bhattacharyya, Wenxin Zheng, Mark A Nelson

  Carcinogenesis. 09/2007; 28(9):2028-35.

  The Cdc2L gene encodes for the cyclin-dependent kinase 11 (CDK11) protein. Loss of one allele of Cdc2L and reduced CDK11 expression has been observed in several cancers, implicating its associationThe Cdc2L gene encodes for the cyclin-dependent kinase 11 (CDK11) protein. Loss of one allele of Cdc2L and reduced CDK11 expression has been observed in several cancers, implicating its association with carcinogenesis. To directly investigate the role of CDK11 in carcinogenesis, we first generated cdc2l haploinsufficient mice by gene trap technology and then studied the susceptibility of these gene-trapped (cdc2l(GT)) mice to chemical-mediated skin carcinogenesis in the 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced two-stage skin carcinogenesis model. Wild-type and cdc2l(GT) mice were subjected to a single topical application of initiation by DMBA and promotion twice a week for 19 weeks with TPA. At 19 weeks, 70% of the cdc2l(GT) mice and 60% of the cdc2l+/+ mice developed benign papillomas. However, there was an overall 3-fold increase in the average number of tumors per mouse observed in cdc2l(GT) mice as compared with cdc2l+/+ mice. There was also an increased frequency of larger papillomas in cdc2l(GT) mice. By using the polymerase chain reaction-restriction fragment length polymorphism assay, we found A to T transversion mutations at the 61st codon of H-ras gene in the papilloma tissue of both cdc2l(GT) mice and cdc2l+/+ mice. Ki-67 staining revealed increased proliferation in the papillomas of cdc2l(GT) (77.75%) as compared with cdc2l+/+ (30.84%) tumors. These studies are the first to show that loss of one allele of cdc2l gene, encoding CDK11, facilitates DMBA/TPA-induced skin carcinogenesis in vivo.

• Profiling of selenomethionine responsive genes in colon cancer by microarray analysis.

  Authors: Anne-Christine Goulet, George Watts, Jean L Lord, Mark A Nelson

  Cancer biology & therapy. 05/2007; 6(4):494-503.

  High-selenium containing yeast is being evaluated in clinical trials against colon polyp recurrence. However, the molecular targets for the anticancer effects of selenium remain unclear. PreviousHigh-selenium containing yeast is being evaluated in clinical trials against colon polyp recurrence. However, the molecular targets for the anticancer effects of selenium remain unclear. Previous studies by our group demonstrated that selenomethionine-induced growth arrest appears to be mediated by activation of ERK and subsequent phosphorylation of RSK and histone H3. These results suggest that selenomethionine can alter gene expression. In the present study, we have used cDNA microarrays to determine whether gene expression differences exist in HCT116 colon cancer cells treated with selenomethionine. These experiments reveal statistically significant expression changes for 50 genes. Genes we found to increase with selenomethionine treatment include KLK6, ATOX1, SGK, GJB2, DAP-1, PLAU, VIM, DPYSL2, STC2 and PXN. Conversely, genes downregulated by selenomethionine include PRKACB, LIM, DEPP, MYC, CDH5, ELF3, VSNL1, SAT and EGLN3. Further analysis of those genes using chromatin immunoprecipitation experiments showed that phosphorylated histone H3 on serine 10 bound to the GJB2 promoter (connexin 26) or the serum glucocorticoid kinase promoter is increased with selenomethionine treatment. Cells overexpressing CX26 or DAP-1 displayed a reduced number of colonies which suggests that these two genes could play a functional role in the growth inhibitory effects of selenomethionine. These data support the notion that selenomethionine-induced growth inhibition is associated with global changes in gene expression. They also demonstrate that selenomethionine can modify chromatin state to alter gene transcription. Finally, our studies provide a practical foundation for the further development of biomarkers to monitor the efficacy of selenomethionine in clinical trials.

• Inhibition of lipoxygenase activity: implications for the treatment and chemoprevention of prostate cancer.

  Authors: Mark A Nelson

  Cancer biology & therapy. 03/2007; 6(2):237.

• Increased gene copy number of the transcription factor E2F1 in malignant melanoma.

  Authors: Mark A Nelson, Steven H Reynolds, Uma N M Rao, Anne-Christine Goulet, Yongmei Feng, Anthony Beas, Barbara Honchak, Jim Averill, David T Lowry, Jamie R Senft, Amy M Jefferson, Robert C Johnson, Linda M Sargent

  Cancer biology & therapy. 05/2006; 5(4):407-12.

  Translocations and unique chromosome break points in melanoma will aid in the identification of the genes that are important in the neoplastic process. We have previously shown a unique translocationTranslocations and unique chromosome break points in melanoma will aid in the identification of the genes that are important in the neoplastic process. We have previously shown a unique translocation in malignant melanoma cells der(12)t(12;20). The transcription factor E2F1 maps to 20q11. Increased expression of E2F has been associated with the autonomous growth of melanoma cells, however, the molecular basis has not yet been elucidated. To this end, we investigated E2F1 gene copy number and structure in human melanoma cell lines and metastatic melanoma cases. Fluorescent in situ hybridization (FISH) analysis using a specific E2F1 probe indicated increased E2F1 gene copies in melanoma cell lines compared to normal melanocytes. We also observed increased copies of the E2F1 gene in lymph node metastases of melanoma. In addition, Western blot analysis demonstrated increased E2F1 protein levels in 8 out of 9 melanoma cell lines relative to normal melanocytes. Inhibition of E2F1 expression with RNAi also reduced melanoma cell growth. Our results suggest that the release of E2F activity by elevated E2F1 gene copy numbers may play a functional role in melanoma growth.

• Studies into the anticancer effects of selenomethionine against human colon cancer.

  Authors: Mark A Nelson, Anne-Christine Goulet, Elizabeth T Jacobs, Peter Lance

  Annals of the New York Academy of Sciences. 12/2005; 1059:26-32.

  Colorectal cancer is the third most frequent fatal malignant neoplasm in the United States and is expected to cause significant morbidity and mortality. The recent recall of cyclooxygenase-2Colorectal cancer is the third most frequent fatal malignant neoplasm in the United States and is expected to cause significant morbidity and mortality. The recent recall of cyclooxygenase-2 inhibitors from clinical trials highlights the need to develop other agents for cancer chemoprevention trials. Intervention strategies with selenium compounds represent a viable option to reduce colon cancer. Here we discuss epidemiologic studies and ongoing clinical trials with selenium. In addition, we discuss preclinical mechanistic studies that provide insights into the biochemical and molecular bases for the anticancer effects of selenomethionine.

• Death-signal-induced relocalization of cyclin-dependent kinase 11 to mitochondria.

  Authors: Yongmei Feng, Maria E Ariza, Anne-Christine Goulet, Jiaqi Shi, Mark A Nelson

  The Biochemical journal. 12/2005; 392(Pt 1):65-73.

  Fas receptor-Fas ligand interaction appears to be important in carcinogenesis, tumour outgrowth and metastasis. Emerging evidence suggests that CDK11 (cyclin-dependent kinase 11) plays a role inFas receptor-Fas ligand interaction appears to be important in carcinogenesis, tumour outgrowth and metastasis. Emerging evidence suggests that CDK11 (cyclin-dependent kinase 11) plays a role in apoptosis and melanoma development. Here, we show that CDK11p110 protein kinase was cleaved after induction of apoptosis by Fas. The N-terminal portion of CDK11p110, CDK11p60, was translocated from the nucleus to the mitochondria. The targeting of CDK11p60 to mitochondria occurred as early as 12 h after treatment. Overexpression of EGFP (enhanced green fluorescent protein)-tagged CDK11p60 could partially break down the mitochondrial membrane potential, induce cytochrome c release and promote apoptosis. Reduction of endogenous CDK11p110 protein levels with siRNA (small interfering RNA) resulted in the suppression of both cytochrome c release and apoptosis. In addition, subcellular fractionation studies of Fas-mediated apoptosis demonstrated that CDK11p60 was associated with the mitochondrial import motor, mitochondrial heat shock protein 70. Taken together, our data suggest that CDK11p60 can contribute to apoptosis by direct signalling at the mitochondria, thereby amplifying Fas-induced apoptosis in melanoma cells.

• The cyclin-dependent kinase 11 interacts with NOT2.

  Authors: Jiaqi Shi, Mark A Nelson

  Biochemical and biophysical research communications. 10/2005; 334(4):1310-6.

  The caspase-processed cyclin-dependent kinase 11 (formerly known as PITSLRE) is implicated in apoptotic signaling. However, the mechanism of apoptotic signal transduction through CDK11(p46) is stillThe caspase-processed cyclin-dependent kinase 11 (formerly known as PITSLRE) is implicated in apoptotic signaling. However, the mechanism of apoptotic signal transduction through CDK11(p46) is still unclear. We used a yeast two-hybrid screening strategy and identified NOT2 as an interacting partner of caspase-processed C-terminal kinase domain of CDK11 (CDK11(p46)). We demonstrate that CDK11(p46) directly interacts with NOT2 in vitro and in human cells. The NOT domain in the C-terminal part of NOT2 is responsible for the association between CDK11(p46) and NOT2. Both NOT2 and CDK11(p46) predominantly co-localized in the nucleus. Furthermore, we show that overexpression of NOT2 reduces luciferase mRNA and induces apoptosis. However, NOT2 is not phosphorylated by CDK11(p46). These findings suggest that CDK11 may contribute to apoptosis by regulating the activity of NOT2 independent of its kinase activity.

• Could the combination of celecoxib and 4HPR be an effective lung cancer treatment?

  Authors: Durga P Cherukuri, Mark A Nelson

  Cancer biology & therapy. 09/2005; 4(8):899-900.

• A specific role for the TFIID subunit TAF4 and RanBPM in neural progenitor differentiation.

  Authors: Adrian Brunkhorst, Mattias Karlén, Jiaqi Shi, Monika Mikolajczyk, Mark A Nelson, Madis Metsis, Ola Hermanson

  Molecular and cellular neurosciences. 07/2005; 29(2):250-8.

  TAF4 is crucial for the activity of many transcription factors, including CREB, RAR and CSL/RBP-Jkappa, but the role for TAF4 in neural development is unknown. Embryonic cortical neural stem cellsTAF4 is crucial for the activity of many transcription factors, including CREB, RAR and CSL/RBP-Jkappa, but the role for TAF4 in neural development is unknown. Embryonic cortical neural stem cells (NSC) showed strong expression of TAF4 that decreased during neuronal but not glial differentiation. In a protein-protein interaction screen, we identified the intracellular signaling factor RanBPM as a co-factor of TAF4. RanBPM co-localized with TAF4 in a subset of mitotic progenitors in vivo and endogenous TAF4 and RanBPM could be co-immunoprecipitated from NSC extracts. Interestingly, co-transfections of TAF4 and RanBPM led to a significant increase in the number of primary neurite processes but no increase in total neurite length, whereas RanBPM and a TAF4 isoform lacking the RanBPM-interacting domain exerted no significant effect. Our results demonstrate that temporally high expression levels of two factors considered to be relatively general in function can influence very specific events in neuronal differentiation.

• The cyclin-dependent kinase 11 interacts with 14-3-3 proteins.

  Authors: Yongmei Feng, Wenqing Qi, Jesse Martinez, Mark A Nelson

  Biochemical and biophysical research communications. 07/2005; 331(4):1503-9.

  Cyclin-dependent kinase 11 isoforms (CDK11) are members of the p34(cdc2) superfamily. They have been shown to play a role in RNA processing and apoptosis. In the present study, we investigate whetherCyclin-dependent kinase 11 isoforms (CDK11) are members of the p34(cdc2) superfamily. They have been shown to play a role in RNA processing and apoptosis. In the present study, we investigate whether CDK11 interacts with 14-3-3 proteins. Our study shows that the putative 14-3-3 binding site (113-RHRSHS-118) within the N-terminal domain of CDK11(p110) is functional. Endogenous CDK11(p110) binds directly to 14-3-3 proteins and phosphorylation of the serine 118 within the RHRSHS motif seems to be required for the binding. Besides, CDK11(p110) is capable of interacting with several different isoforms of 14-3-3 proteins both in vitro and in vivo. The interaction of 14-3-3 gamma with CDK11(p110) occurs throughout the entire cell cycle and reaches maximum at the G2/M phase. Interestingly, 14-3-3 gamma shows strong interaction with N-terminal portion of caspase-cleaved CDK11(p110) (CDK11(p60)) product at 48 h after Fas treatment, which correlates with the maximal cleavage level of CDK11(p110) and the maximum activation level of CDK11 kinase activity during apoptosis. Collectively, these results suggest that CDK11 kinases could be regulated by interaction with 14-3-3 proteins during cell cycle and apoptosis.