The nuclear matrix shell proteome of human epidermis.

Background: Proteomic approaches have identified cancer specific biomarker proteins in the nuclear matrix fraction of cancer cells. We wanted to determine whether a similar approach could be used to investigate melanoma biomarkers.

Objective: Since it was not clear that a nuclear matrix fraction could be isolated from the intact human epidermis, we first wanted to determine whether a nuclear matrix fraction could be isolated from the intact epidermis of human skin.

Differential gene expression in primary human skin keratinocytes and fibroblasts in response to ionizing radiation.

Although skin is usually exposed during human exposures to ionizing radiation, there have been no thorough examinations of the transcriptional response of skin fibroblasts and keratinocytes to radiation. The transcriptional response of quiescent primary fibroblasts and keratinocytes exposed to from 10 cGy to 5 Gy and collected 4 h after treatment was examined. RNA was isolated and examined by microarray analysis for changes in the levels of gene expression.

Transient dephosphorylation of p53 serine 376 as an early response to ionizing radiation.

In a previous paper we reported that the cytoplasmic sequestered p53 in cells of the SK-N-SH neuroblastoma cell line could be induced to translocate to the nucleus by exposure to ionizing radiation. We have extended these studies to determine the fate of p53 in HCT116 colorectal carcinoma cells where constitutive p53 protein resides in the nucleus. A continuous increase in the nuclear p53 protein was observed in irradiated cells beginning 1 h after irradiation that persisted for 8 h.

Protein phosphorylation in irradiated human melanoma cells.

In the present study, we examined the response of confluent, primary human fibroblasts and cells of a melanoma (YUSAC2) cell line to ionizing radiation mediated through post-translational protein phosphorylation. Since the purpose of our study was to identify novel radiation-induced phosphoproteins in the DNA damage stress response of melanoma cells, we were primarily interested in changes in protein phosphoserine expression at early times after irradiation. Our rationale was that by examining the overall protein phosphorylation profile (the phosphoproteome) in irradiated cells, we might discover novel radiation-induced phosphoproteins that distinguish fibroblasts from melanoma cells.

Melanoma cells express elevated levels of phosphorylated histone H2AX foci.

When human cells sustain a DNA double-strand break (dsb), histone H2AX in chromatin surrounding the DNA break is phosphorylated, marking repair foci. The number of phosphorylated histone H2AX (gammaH2AX) foci approximates the number of dsb present in the cell's nuclear DNA. We observed 0.