Search results for "DMBA"

2017

ABSTRACTTissue immunosurveillance is an important mechanism to prevent cancer. Skin treatment with the carcinogen 7,12-dimethylbenz(a)anthracene (DMBA), followed by the tumor promoter 12-O-tetra-decanoyl-phorbol-13-acetate (TPA), is an established murine model for squamous cell carcinoma (SCC). However, the innate immunological events occurring during the initiation of chemical carcinogenesis with DMBA remain elusive. Here, we discovered that natural killer (NK) cells and Langerhans cells (LC) cooperate to impair this oncogenic process in murine skin. The depletion of NK cells or LC caused an accumulation of DNA-damaged, natural killer group 2D-ligand (NKG2D-L) expressing keratinocytes and …

C3 Drives Inflammatory Skin Carcinogenesis Independently of C5

2021

Nonmelanoma skin cancer such as cutaneous squamous cell carcinoma (cSCC) is the most common form of cancer and can occur as a consequence of DNA damage to the epithelium by UVR or chemical carcinogens. There is growing evidence that the complement system is involved in cancer immune surveillance; however, its role in cSCC remains unclear. Here, we show that complement genes are expressed in tissue from patients with cSCC, and C3 activation fragments are present in cSCC biopsies, indicating complement activation. Using a range of complement-deficient mice in a two-stage mouse model of chemically-induced cSCC, where a subclinical dose of 7,12-dimethylbenz[a]anthracene causes oncogenic mutatio…

1979

Oxidation of tertiary amines with N-chloronylon 66 (NCN) was investigated in several organic solvents. NCN was found to oxidize N,N-dimethylaniline (DMA) at room temperature to give N-methylaniline with 15–50% yield, depending on the solvents used. Oxidation of N,N-dimethylbenzylamine (DMBA) gave benzaldehyde with 15–30% yield and a small amount of N-methylbenzylamine. A mechanism was discussed. For comparison, N-chlorosuccinimide, a low molecular N-chloro-compound, was also used for oxidation of DMA and DMBA.

DNA repair protein MGMT protects against N-methyl-N-nitrosourea-induced conversion of benign into malignant tumors

2003

Tumor formation is a multi-step process that can be divided into the stages of tumor initiation, promotion and progression. Previously, we showed that overexpression in skin of mice of the DNA repair protein O(6)-methylguanine-DNA methyltransferase (MGMT) protects against N-methyl-N-nitrosourea (MNU)-induced tumor initiation without affecting tumor promotion. This indicated that O(6)-methylguanine, which is specifically repaired by MGMT, is a major tumor-initiating lesion. Here we extended this transgenic approach to the study of tumor progression. Benign papillomas that arose on the skin of CkMGMT transgenic mice upon initiation with 7,12-dimethylbenz[a]anthracene (DMBA) and promotion by 1…

Chronic exposure to a GSM-like signal (mobile phone) does not stimulate the development of DMBA-induced mammary tumors in rats: results of three cons…

2002

Certain epidemiological and experimental studies raised concerns about the safety of radiofrequency (RF) electromagnetic fields because of a possible increased risk of leukemia and lymphoma. In this study, an RF field used in mobile telecommunication was tested using 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors in female Sprague-Dawley rats as a model for human breast cancer. Three experiments were carried out under strictly standardized conditions and were started on the same day of three consecutive years. The field consisted of a GSM-like signal (900 MHz pulsed at 217 Hz, pulse width 577 micros) of relatively low power flux density (100 microW/cm(2) +/- 3 dB) and was appl…

Organoplatinum(II) Complexes Self-Assemble and Recognize AT-Rich Duplex DNA Sequences

2021

The specific recognition of AT-rich DNA sequences opens up the door to promising diagnostic and/or therapeutic strategies against gene-related diseases. Here, we demonstrate that amphiphilic PtII complexes of the type [Pt(dmba)(N∧N)]NO3 (dmba = N,N-dimethylbenzylamine-κN, κC; N∧N = dpq (3), dppz (4), and dppn (5)) recognize AT-rich oligonucleotides over other types of DNA, RNA, and model proteins. The crystal structure of 4 shows the presence of significant π-stacking interactions and a distorted coordination sphere of the d8 PtII atom. Complex 5, containing the largest π-conjugated ligand, forms supramolecular assemblies at high concentrations under aqueous environment. However, its aggreg…

erbB expression changes in ethanol and 7,12- dimethylbenz (a)anthracene-induced oral carcinogenesis.

2012

The authors (Garcia Carrancá A, Zentero Galindo E, Jiménez Farfán MD and Hernandez Guerrero JC) express that one of the figures of the original article (Jacinto-Alemán LF, García-Carrancá A, LeybaHuerta ER, Zenteno-Galindo E, Jiménez-Farfán MD, Hernández-Guerrero JC. erbB expression changes in ethanol and 7,12- dimethylbenz (a)anthracene-induced oral carcinogenesis. Med Oral Patol Oral Cir Bucal. 2013 Mar 1;18(2):e325-31.) corresponding to Western blots have not been found and the voluntary alteration of this figure is evident. The coauthors Alejandro García Carranca, Edgar Zenteno Galindo, Maria Dolores Jiménez Farfán and Juan Carlos Hernández Guerrero have made the decision to take back w…

Dietary exposure in utero and during lactation to a mixture of genistein and an anti-androgen fungicide in a rat mammary carcinogenesis model

2015

Endocrine disruptors may play substantial roles in the high incidence of breast cancer. We previously described how early exposure to the mixture of phytoestrogen genistein (G) and the anti-androgen vinclozolin (V) affects peripubertal mammary development. This study evaluates the carcinogenic potential of exposure to V alone or associated with G from conception until weaning in Wistar rats. Dams were exposed to V, G or GV during pregnancy/lactation. At PND50 offspring were treated with DMBA[7,12-dimethylbenz(a)anthracene]. V or GV maternal exposure decreased number of DMBA-induced mammary tumors in the offspring, without significant modifications in tumor incidence, multiplicity and latenc…

Skin response to a carcinogen involves the xenobiotic receptor pregnane X receptor.

2015

Skin is in daily contact with potentially harmful molecules from the environment such as cigarette smoke, automobile emissions, industrial soot and groundwater. Pregnane X receptor (PXR) is a transcription factor expressed in liver and intestine that is activated by xenobiotic chemicals including drugs and environmental pollutants. Topical application of the tumor initiator 7,12-dimethylbenz(a)anthracene (DMBA) enhances Pxr, Cyp1a1, Cyp1b1 and Cyp3a11, but not Ahr expression in the skin. Surprisingly, DMBA-induced Pxr upregulation is largely impaired in Langerin(+) cell-depleted skin, suggesting that DMBA mainly triggers Pxr in Langerin(+) cells. Furthermore, PXR deficiency protects from DN…