Transforming growth factor-ß enhances invasion and metastasis in Ras-transfected human malignant epidermal keratinocytes.

Transforming growth factor-ß (TGF-ß) is known to act as a tumour suppressor early in carcinogenesis, but then switches to a pro-metastatic factor in some late stage cancers. However, the actions of TGF-ß are context dependent, and it is currently unclear how TGF-ß influences the progression of human squamous cell carcinoma (SCC). This study examined the effect of overexpression of TGF-ß1 or TGF-ß2 in Ras-transfected human malignant epidermal keratinocytes that represent the early stages of human SCC. In vitro, the proliferation of cells overexpressing TGF-ß1 or TGF-ß2 was inhibited by exogenous TGF-ß1; cells overexpressing TGF-ß1 also grew more slowly than controls, but the growth rate of TGF-ß2 overexpressing cells was unaltered. However, cells that overexpressed either TGF-ß1 or TGF-ß2 were markedly more invasive than controls in an organotypic model of SCC. The proliferation of the invading TGF-ß1 overexpressing cells in the organotypic assays was higher than controls. Similarly, tumours formed by the TGF-ß1 overexpressing cells following transplantation to athymic mice were larger than tumours formed by control cells and proliferated at a higher rate. Our results demonstrate that elevated expression of either TGF-ß1 or TGF-ß2 in cells that represent the early stages in the development of human SCC results in a more aggressive phenotype.

GeMInA, Genomic Metadata for Infectious Agents, a geospatial surveillance pathogen database.

The Gemina system (http://gemina.igs.umaryland.edu) identifies, standardizes and integrates the outbreak metadata for the breadth of NIAID category A-C viral and bacterial pathogens, thereby providing an investigative and surveillance tool describing the Who [Host], What [Disease, Symptom], When [Date], Where [Location] and How [Pathogen, Environmental Source, Reservoir, Transmission Method] for each pathogen. The Gemina database will provide a greater understanding of the interactions of viral and bacterial pathogens with their hosts and infectious diseases through in-depth literature text-mining, integrated outbreak metadata, outbreak surveillance tools, extensive ontology development, metadata curation and representative genomic sequence identification and standards development. The Gemina web interface provides metadata selection and retrieval of a pathogen's; Infection Systems (Pathogen, Host, Disease, Transmission Method and Anatomy) and Incidents (Location and Date) along with a hosts Age and Gender. The Gemina system provides an integrated investigative and geospatial surveillance system connecting pathogens, pathogen products and disease anchored on the taxonomic ID of the pathogen and host to identify the breadth of hosts and diseases known for these pathogens, to identify the extent of outbreak locations, and to identify unique genomic regions with the DNA Signature Insignia Detection Tool.

TGF-ß inhibits metastasis in late stage human squamous cell carcinoma of the skin by a mechanism that does not involve Id1.

It is now generally accepted that TGF-ß acts as a pro-metastatic factor in advanced human breast cancer. However, it is well documented, that TGF-ß is context dependent, and whether the TGF-ß pathway switches to promote metastasis during the progression of squamous cell carcinoma (SCC) is unknown. This study examined the role of TGF-ß signalling in SCC using a series of genetically related keratinocyte cell lines representing later stages of the disease, stably transduced with a dominant negative TßRII cDNA (dnTßRII). We demonstrated that clones expressing dnTßRII lost their growth inhibitory response to TGF-ßin vitro, while ligand expression remained unchanged. Following transplantation of transduced cells to athymic mice in vivo, we showed that attenuation of the TGF-ß signal resulted in a loss of differentiation and increased metastasis. In human tissue samples loss of TGF-ß signal transduction as measured by pSmad2 activity also correlated with a loss of differentiation. Id1, previously shown to be down regulated by TGF-ß, an inhibitor of differentiation and associated with metastasis, was weakly expressed in focal areas of a small number of human tumours but expression did not correlate with low levels of pSmad2. Our data demonstrate that TGF-ß does not switch to promote metastasis in late stage human SCC of the skin and that inhibition of TGF-ß signalling results in a loss of differentiation and increased metastasis in the later stages of this disease.

Cell death induced by N-(4-hydroxyphenyl)retinamide in human epidermal keratinocytes is modulated by TGF-beta and diminishes during the progression of squamous cell carcinoma.

It has been demonstrated that the chemopreventive agent N-(4-hydroxyphenyl)retinamide (4-HPR) induces apoptotic cell death, but recent data has suggested that late stage/recurrent tumours lose their response to 4-HPR-induced cell death by mechanisms that are unknown. Our study investigated the ability of 4-HPR to induce cell death in keratinocyte cell lines that represent different stages of carcinogenesis and the role of TGF-beta signalling in the induction of cell death by 4-HPR. We show that treatment of the immortalised keratinocyte cell line HaCaT with 10(-5) M 4-HPR induced cell death by apoptosis and caused an accumulation of cells in the G0/G1 phase of the cell cycle. Using a genetically related series of human skin keratinocytes derived from HaCaT that reflect tumour progression and metastasis in vivo, we demonstrate that 4-HPR-induced cell death and apoptosis is attenuated in the more aggressive tumour cell lines but that a reduced level of response is retained. Response to TGF-beta-induced growth inhibition was also reduced in the more aggressive cell lines. Treatment of HaCaT cells with 4-HPR induced TGF-beta2 expression and an increase in the amount of active TGF-beta in the culture medium. The inhibition of TGF-beta signalling attenuated 4-HPR-induced apoptosis and both TGF-beta1 and TGF-beta2 potentiated 4-HPR-induced apoptosis and enhanced 4-HPR-induced growth inhibition. Our results demonstrate that loss of response to 4-HPR correlates with a loss of response to the growth inhibitory effects of TGF-beta and that adjuvant therapies that upregulate TGF-beta may enhance the chemopreventive effects of 4-HPR.