We previously demonstrated that a wild-type alternatively spliced p53 (p53as) RNA exists in mouse cultured cells and normal mouse tissues at approximately 25 to 33% of the level of the major p53 RNA form. The alternative RNA transcript is 96 nucleotides longer than the major transcript as a result of alternative splicing of intron 10 sequences. The protein expected to be generated from the p53as transcript is 9 amino acids shorter than the major p53 protein and has 17 different amino acids at the carboxyl terminus. We report here that p53as protein exists in nontransformed and malignant epidermal cells and is localized to the nucleus. In addition, p53as protein is preferentially expressed during the G2 phase of the cell cycle and in cells with greater than G2 DNA content compared with the major p53 protein, which is preferentially expressed in G1. The p53as immunoreactivity is elevated and shifted to the G1 phase of the cell cycle following actinomycin D treatment of nontransformed cells but not malignant cells. In view of the dimerization and tetramerization of p53 protein which may be necessary for its DNA binding and transcriptional activation activities, the presence of p53as protein in cells has important implications for understanding the physiological function(s) of the p53 gene.

Endogenous p53 protein generated from wild-type alternatively spliced p53 RNA in mouse epidermal cells.

Proopiomelanocortin (POMC) is a 31 kDa prohormone that is processed to various bioactive peptides, including adrenocorticotropin (ACTH), melanotropins (alpha, beta, gamma-MSH), lipotropins, and endorphins POMC is expressed not only in the pituitary gland but also in a variety of nonpituitary organs and tumors, including melanomas We previously showed that normal human melanocytes produce and secrete alpha-MSH and ACTH, and furthermore, that advanced melanoma cells generally produce higher amounts of POMC peptides that correlate with tumor progression To elucidate the mechanism of this upregulation, the expression of genes encoding corticotropin-releasing hormone (CRH) and its receptor, CRH-R, as well as POMC and the MSH receptor (MC1-R), was evaluated by reverse transcriptase-polymerase chain reaction using cultured human melanoma cells, nevus cells, and normal melanocytes Our results show that all melanocytic cells express CRH, CRH-R, POMC, and MC1-R, with highest intensities in melanoma cells Furthermore, immunohistochemistry shows that CRH as well as POMC is strongly expressed in advanced melanomas, such as vertically growing lesions of acral lentiginous, nodular and metastatic melanomas, in contrast to negative expression in nevus cells These results indicate that tumor progression accentuates CRH, CRH-R, and POMC expression by melanoma cells

https://www.jidsponline.org/article/S1087-0024(15)30245-8/pdf

Expression of Proopiomelanocortin, Corticotropin-Releasing Hormone (CRH), and CRH Receptor in Melanoma Cells, Nevus Cells, and Normal Human Melanocytes

Negative regulation of the NF-κB transcription factor is essential for tissue homeostasis in response to stress and inflammation. NF-κB activity is regulated by a variety of biochemical mechanisms including phosphorylation, acetylation, and ubiquitination. In this study, we provide the first experimental evidence that NF-κB is regulated by SUMOylation, where the RelA subunit of NF-κB is SUMOylated by PIAS3, a member of the PIAS (protein inhibitor of activated STAT) protein family with E3 SUMO ligase activity. PIAS3-mediated NF-κB repression was compromised by either RelA mutant resistant to SUMOylation or PIAS3 mutant defective in SUMOylation. PIAS3-mediated SUMOylation of endogenous RelA was induced by NF-κB activation thus forming a negative regulatory loop. The SUMOylation of endogenous RelA was enhanced in IκBα null as compared with wild type fibroblasts. The RelA SUMOylation was induced by TNFα but not leptomycin B mediated RelA nuclear translocation. Furthermore, RelA mutants defective in DNA binding were not SUMOylated by PIAS3, suggesting that RelA DNA binding is a signal for PIAS3-mediated SUMOylation. These results support a novel negative feedback mechanism for NF-κB regulation by PIAS3-mediated RelA SUMOylation.

/pdf/nf-kb-repression-by-pias3-mediated-rela-sumoylation-256i7guscm.pdf

NF-κB Repression by PIAS3 Mediated RelA SUMOylation

The role of dietary factors in inhibiting or delaying the development of non-melanoma skin cancer (NMSC) has been investigated for many years. Cardamom, which is a dietary phytoproduct, has been commonly used in cuisines for flavour and has numerous health benefits, such as improving digestion and stimulating metabolism and having antitumorigenic effects. We have investigated the efficacy of dietary cardamom against 7,12-dimethylbenz[a]anthracene (DMBA)-induced skin papillomatogenesis in Swiss albino mice that closely resembles human NMSC. Mice were grouped into normal wild type (untreated), vehicle-treated (acetone), carcinogen-treated (DMBA), and DMBA and cardamom-treated (DMBA+CARD) to delineate the role of cardamom against DMBA-induced papillomatogenesis. Oral administration of cardamom to DMBA-treated mice up-regulated the phase II detoxification enzymes, such as glutathione-S-transferase and glutathione peroxidase, probably via activation of nuclear factor erythroid-2-related factor 2 transcription factor in 'DMBA+CARD' mice. Furthermore, reduced glutathione, glutathione reductase, superoxide dismutase and catalase were also up-regulated by cardamom in the same 'DMBA+CARD' group of mice compared with DMBA-treated mice. Cardamom ingestion in DMBA-treated mice blocked NF-κB activation and down-regulated cyclo-oxygenase-2 expression. As a consequence, both the size and the number of skin papillomas generated on the skin due to the DMBA treatment were reduced in the 'DMBA+CARD' group. Thus, the results from the present study suggest that cardamom has a potential to become a pivotal chemopreventive agent to prevent papillomagenesis on the skin.

/pdf/antioxidative-effects-of-the-spice-cardamom-against-non-2ednebjhzq.pdf

Antioxidative effects of the spice cardamom against non-melanoma skin cancer by modulating nuclear factor erythroid-2-related factor 2 and NF-κB signalling pathways.

A novel spermatogenesis associated factor (SPAF) was found to be aberrantly expressed at the malignant conversion stage in a clonal epidermal model of chemical carcinogenesis. Sequence analysis revealed two ATPase modules, classifying this gene as a new member of the AAA-protein family (ATPase associated with diverse activities). Immunohistochemical staining of mouse testis sections with SPAF antibody localized expression to spermatogonia and early spermatocytes in the basal compartment of the seminiferous tubules. Northern and Western analysis of SPAF expression in testes of mice at different developmental stages confirmed its expression at early stages of spermatogenesis. In view of a mitochondrial-localization-like signal, sequence similarities to membrane-associated proteins, ATP binding properties, and intracellular expression patterns in testis, we speculate that SPAF protein may be involved in morphological and functional mitochondrial transformations during spermatogenesis. Ectopic expression of the SPAF gene in malignant epidermal cells may signify adoption of an early germ cell-like phenotype advantageous in malignant conversion.

Kyung An Han

Papers

7,12-Dimethylbenz[a]Anthracene-Induced Mouse Keratinocyte Malignant Transformation Independent of Harvey Ras Activation