casein-kinase-ii and Skin-Neoplasms

Bromodomain-containing protein 4 (Brd4) is a cellular chromatin-binding factor and transcriptional regulator that recruits sequence-specific transcription factors and chromatin modulators to control target gene transcription. Papillomaviruses (PVs) have evolved to hijack Brd4's activity in order to create a facilitating environment for the viral life cycle. Brd4, in association with the major viral regulatory protein E2, is involved in multiple steps of the PV life cycle including replication initiation, viral gene transcription, and viral genome segregation and maintenance. Phosphorylation of Brd4, regulated by casein kinase II (CK2) and protein phosphatase 2A (PP2A), is critical for viral gene transcription as well as E1- and E2-dependent origin replication. Thus, pharmacological agents regulating Brd4 phosphorylation and inhibitors blocking phospho-Brd4 functions are promising candidates for therapeutic intervention in treating human papillomavirus (HPV) infections as well as associated disease.

Topics: Carcinogenesis; Casein Kinase II; Cell Cycle Proteins; DNA-Binding Proteins; Gene Expression Regulation; Host-Pathogen Interactions; Humans; Keratinocytes; Nuclear Proteins; Oncogene Proteins, Viral; Papillomaviridae; Papillomavirus Infections; Phosphorylation; Protein Phosphatase 2; Signal Transduction; Skin Neoplasms; Transcription Factors; Transcription, Genetic; Virus Replication

Dietary supplements such as vitamins and minerals are widely used in the hope of improving health but may have unidentified risks and side effects. In particular, a pathogenic link between dietary supplements and specific oncogenes remains unknown. Here we report that chondroitin-4-sulfate (CHSA), a natural glycosaminoglycan approved as a dietary supplement used for osteoarthritis, selectively promotes the tumor growth potential of BRAF V600E-expressing human melanoma cells in patient- and cell line-derived xenograft mice and confers resistance to BRAF inhibitors. Mechanistically, chondroitin sulfate glucuronyltransferase (CSGlcA-T) signals through its product CHSA to enhance casein kinase 2 (CK2)-PTEN binding and consequent phosphorylation and inhibition of PTEN, which requires CHSA chains and is essential to sustain AKT activation in BRAF V600E-expressing melanoma cells. However, this CHSA-dependent PTEN inhibition is dispensable in cancer cells expressing mutant NRAS or PI3KCA, which directly activate the PI3K-AKT pathway. These results suggest that dietary supplements may exhibit oncogene-dependent pro-tumor effects.

Topics: Animals; Antinematodal Agents; Carcinogens; Casein Kinase II; Cell Proliferation; Cell Transformation, Neoplastic; Chondroitin Sulfates; Dietary Supplements; Drug Resistance, Neoplasm; Female; GTP Phosphohydrolases; HEK293 Cells; HT29 Cells; Humans; Melanoma; Membrane Proteins; Mice; Mice, Inbred NOD; Mice, Nude; Mice, Transgenic; Mutation; NIH 3T3 Cells; Nuclear Proteins; Phosphorylation; Protein Kinase Inhibitors; Proto-Oncogene Proteins B-raf; PTEN Phosphohydrolase; Signal Transduction; Skin Neoplasms; Transcription Factors; Xenograft Model Antitumor Assays

In melanoma, mutant and thereby constantly active neuroblastoma rat sarcoma (NRAS) affects 15-20% of tumors, contributing to tumor initiation, growth, invasion, and metastasis. Recent therapeutic approaches aim to mimic RAS extinction by interfering with critical signaling pathways downstream of the mutant protein. This study investigates the phosphoproteome of primary human melanocytes bearing mutations in the two hot spots of NRAS, NRAS(G12) and NRAS(Q61). Stable isotope labeling by amino acids in cell culture followed by mass spectrometry identified 14,155 spectra of 3,371 unique phosphopeptides mapping to 1,159 proteins (false discovery rate < 2%). Data revealed pronounced PI3K/AKT signaling in NRAS(G12V) mutant cells and pronounced mitogen-activated protein kinase (MAPK) signaling in NRAS(Q61L) variants. Computer-based prediction models for kinases involved, revealed that CK2α is significantly overrepresented in primary human melanocytes bearing NRAS(Q61L) mutations. Similar differences were found in human NRAS(Q61) mutant melanoma cell lines that were also more sensitive to pharmacologic CK2α inhibition compared with NRAS(G12) mutant cells. Furthermore, CK2α levels were pronounced in patient samples of NRAS(Q61) mutant melanoma at the mRNA and protein level. The preclinical findings of this study reveal that codon 12 and 61 mutant NRAS cells have distinct signaling characteristics that could allow for the development of more effective, mutation-specific treatment modalities.

Topics: Casein Kinase II; GTP Phosphohydrolases; Humans; Mass Spectrometry; Melanocytes; Melanoma; Membrane Proteins; Mitogen-Activated Protein Kinases; Mutation; Phosphatidylinositol 3-Kinase; Phosphopeptides; Proteomics; Proto-Oncogene Proteins c-akt; RNA, Messenger; Signal Transduction; Skin Neoplasms

Skin cancer is the most common form of malignancy in the world with epidemic proportions. Identifying the biochemical and molecular mechanisms underlying the events leading to tumors is paramount to designing new and effective treatments that may aid in treating and/or preventing skin cancers. Herein we identify p38 MAPK, along with its positive modulator, Gadd45a, as important regulators of nucleocytoplasmic shuttling of the adenomatous polyposis coli (APC) tumor suppressor. APC normally functions to block beta-catenin from promoting cell proliferation and migration/invasion. Keratinocytes lacking proper p38 MAPK activation, either due to lack of Gadd45a or through the use of p38 MAPK-specific inhibitors, are unable to effectively transport APC into the nucleus. We also show that p38 MAPK is able to directly associate with and modulate both casein kinase 2 (CK2) and protein kinase A (PKA), which promote and block APC nuclear import, respectively. We demonstrate that p38 MAPK is able to not only enhance CK2 kinase activity but also suppress PKA kinase activity. Moreover, lack of normal p38 MAPK activity in either Gadd45a-null keratinocytes or in p38 MAPK inhibitor treated keratinocytes leads to decreased CK2 activity and increased PKA activity. In either case, disruption of APC nuclear import results in elevated levels of free cellular, and potentially oncogenic, beta-catenin. Numerous tumors, including skin cancers, are associated with high levels of beta-catenin, and our data indicate that p38 MAPK signaling, along with Gadd45a, may provide tumor suppressor-like functions in part by promoting APC nuclear localization and effective beta-catenin regulation.

Topics: Adenomatous Polyposis Coli; Adenomatous Polyposis Coli Protein; Animals; beta Catenin; Casein Kinase II; Cell Cycle Proteins; Cell Movement; Cell Nucleus; Cell Proliferation; Cells, Cultured; Cyclic AMP-Dependent Protein Kinases; Cytoplasm; Cytoskeletal Proteins; Humans; Immunoblotting; Immunohistochemistry; Immunoprecipitation; Keratinocytes; Mice; Mice, Transgenic; Microscopy, Fluorescence; Models, Biological; Neoplasm Invasiveness; Nuclear Proteins; p38 Mitogen-Activated Protein Kinases; Signal Transduction; Skin Neoplasms; Trans-Activators

The benign dermal nevus can be transformed into malignant melanoma. The possibility that the transformation process is accompanied with enhanced casein kinase II (CK II) activity was investigated. The tissue samples were obtained by incisional biopsy, homogenized and ultracentrifuged. The supernatant was injected onto a Mono Q column. CK II was monitored with [gamma-32P]GTP and its specific substrate RRREEETEEE. The CK II stimulators, spermine and polylysine, the inhibitors heparin, quercetin, poly (Glu-Tyr) 4:1 and 2,3-bisphosphoglycerate were used for identification. CK II activity in metastatic melanoma samples was about 2.5-fold higher than in dermal nevus. These results support our hypothesis that CK II takes a central role in the non-transformed and transformed skin proliferation.

Topics: Amino Acid Sequence; Casein Kinase II; Humans; Melanoma; Molecular Sequence Data; Protein Serine-Threonine Kinases; Skin Neoplasms