Biomedical subjects

Craig D Woodworth

Publications and source records attributed to Craig D Woodworth.

4 recordsLinked to original sources

PubMed2005

Human epithelial cells increase their rigidity with ageing in vitro: direct measurements.

The decrease in elasticity of epithelial tissues with ageing contributes to many human diseases. This change was previously attributed to increased crosslinking of extracellular matrix proteins. Here we show that individual human epithelial cells also become significantly more rigid during ageing in vitro. Using atomic force microscopy (AFM), we found that the Young's modulus of viable cells was consistently increased two- to four-fold in older versus younger cells. Direct visualization of the cytoskeleton using a novel method involving the AFM suggested that increased rigidity of ageing cells was due to a higher density of cytoskeletal fibres. Our results identify a unique mechanism that might contribute to the age-related loss of elasticity in epithelial tissues.

Aging↗

PubMed2005

Inhibition of the epidermal growth factor receptor increases expression of genes that stimulate inflammation, apoptosis, and cell attachment.

The epidermal growth factor receptor (EGFR) is overexpressed in several types of human cancer, and inhibition of EGFR function is a promising strategy for cancer therapy. We used cDNA microarrays to examine alterations in gene expression after treatment of carcinoma cells with PD153035, a specific and reversible inhibitor of EGFR function. When human cervical carcinoma cells were grown on a collagen substrate in three-dimensional organotypic culture, untreated cells expressed high levels of EGFR RNA and invaded the underlying collagen. Blocking EGFR function decreased DNA synthesis and inhibited invasion in a dose-dependent manner. Microarray analyses identified 312 genes that were significantly increased or decreased in expression after EGFR inhibition. Many could be classified into one of four functional groups including genes that (a) stimulate inflammation and innate immunity, (b) promote cell attachment, (c) enhance apoptosis, and (d) inhibit cell cycle progression. PD153035 induced a dose-dependent activation of nuclear factor kappaB, a transcription factor that stimulates proinflammatory gene expression. Our results identify alterations in gene expression caused by EGFR inhibition and show that this response varies significantly in different cell lines.

Antineoplastic Agents↗

PubMed2004

Strain-dependent differences in malignant conversion of mouse skin tumors is an inherent property of the epidermal keratinocyte.

The multistage evolution of squamous skin tumors induced by chemical or viral carcinogens on mice from different genetic backgrounds has been a valuable model to define low penetrance loci that determine cancer susceptibility or resistance. Susceptibility determinants are multigenic, stage-specific, dependent on the carcinogenesis protocol, and in the case of initiating events, intrinsic properties of keratinocytes. In this study we examined the malignant conversion frequency of keratinocytes derived from FVB/N, inbred SENCARA/Pt, BALB/c or C57BL/6 mouse strains that differ substantially in the frequency of progression from papilloma to carcinoma. Keratinocytes were cultured from newborn mice and tested in an in vitro malignant conversion assay induced by a chemical carcinogen or immortalized by infection with replication defective human papillomavirus type 16 (HPV-16) E6/E7 retroviruses and tested for malignancy by grafting immortalized cell lines to nude mice. In vitro, FVB/N keratinocytes were 10-fold more sensitive to chemically induced malignant conversion than keratinocytes from other strains, consistent with the known sensitivity of this strain to pre-malignant progression in vivo. The E6/E7 genes induced immortalization of keratinocytes from FVB/N, SENCARA/Pt or C57BL/6 mice more efficiently than BALB/c, and HPV-16-immortalized FVB/N keratinocytes formed tumors more frequently (64%) than SENCARA/Pt (31%) BALB/c (1.9%) or C57BL/6 (2.5%). Furthermore, 78% of the tumors formed by FVB/N keratinocytes progressed to squamous carcinomas compared with 46% for SENCARA/Pt-derived cells and <3% for the others. In F(1) offspring of crosses from SENCARA/Pt and FVB/N mice, both the papilloma incidence and frequency of malignant conversion reflected the SENCARA/Pt parent indicating that predisposition to pre-malignant progression is not a dominant characteristic. This predisposition is an intrinsic property of the target keratinocytes and as such should be amenable to further study in isolated cells.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed2002

HPV innate immunity.

HPV infections of the epidermis and anogenital tract occur frequently in healthy individuals, and 'high risk' HPV types are a major risk factor for cervical cancer. The first line of defense against HPV is the innate immune system, which provides non specific protection against a variety of pathogens and also enhances the adaptive immune response. However, HPV-infected cells often evade innate immune recognition and elimination. HPV gene expression and release of virus occur in superficial squamous cells where virus antigens are not readily detected, and keratinocytes are not lysed during HPV infection so there is no inflammatory response. In addition, HPV early proteins inhibit specific components of the innate immune system. E6 and E7 inhibit signaling by type I interferons and decrease expression of multiple interferon-inducible genes. E5 and E7 inhibit expression of major histocompatibility complex class I proteins on the cell surface. HPV-infected cells are resistant to lysis by natural killer (NK) cells, but are sensitive to cytokine-activated NK cells. Activated macrophages also kill HPV-infected cells and control malignant development. Thus, innate immunity is important for prevention of HPV infections, but HPV often persists due to evasion or inactivation of innate defenses.

Cytokines↗