Nicholas Lintell

Polymorphisms of the VDR gene are associated with presence of solar keratoses on the skin

Background  Vitamin D has a range of biological effects including antiproliferative functions that are mediated through its receptors, encoded by the VDR gene.

The Anomalous Einstein-Stokes Behaviour of Oxygen and Other Low Molecular Weight Diffusants

Almost a century ago, Einstein and Sutherland independently derived equations that describe the relationship between diffusion of solutes and the molecular parameters of those solutes. In that time it has been recognized that, although the equations adequately describe the diffusion of large and medium-sized molecules, there is deviation from this relationship for small molecules. Many authors have attempted to redefine the equations for diffusion, with varying degrees of success, but generally have not attempted to consider the fundamental events that may be occurring at the molecular level during the diffusion of small molecules. In this presentation, we attempt to provide such an explanation, particularly with respect to the diffusion of oxygen through water. We consider the possibility of a random rotational model that complements the (slower) translational process of traditional diffusion and thereby provides accelerated diffusion of small molecules. It is hoped that our description of this model may provide a basis for the development of mathematical modelling of the process.

Pten and Ndufb8 aberrations in cervical cancer tissue

Cervical cancer is one of the worlds major health issues. Despite many studies in this field, the carcinogenetic events of malignant conversion in cervical tumours have not been significantly characterised. The first aim of this project was to investigate the mutation status of the tumour suppressor gene- Phosphatase and Tension Homolog (PTEN)--in cervical cancer tissue. The second aim of this study was the analysis in the same cervical cancer tissue for aberrations in the mitochondrial electron transport chain subunit gene NDUFB8, which is localised to the same chromosomal contig as PTEN. The third aim was the evaluation of the potential therapeutic anti-cancer drug 2,4-Thiazolidinediones (TZDs) and its affect in regulating the PTEN protein in a cervical cancer cell line (HeLa). To approach the aims, paraffin-embedded cancerous cervical tissue and non-cancerous cervical tissue were obtained. DNA recovered from those tissues was then used to investigate the putative genomic changes regarding the NDUFB8 gene utilising SYBR Green I Real-Time PCR. The PTEN gene was studied via Dual-Labelled probe Real-Time PCR. To investigate the protein expression change of the PTEN protein, HeLa cells were firstly treated with different concentrations of 2,4-Thiazolidinediones and the level of PTEN protein expression was then observed utilising standard protein assays. Results indicated that there were putative copy-number changes between the cancerous cervical tissue and non-cancerous cervical tissue, with regard to the PTEN locus. This implies a potential gain of the PTEN gene in cancerous cervical tissue. With regards to normal cervical tissue versus cancerous cervical tissue no significant melting temperature differences were observed with the SYBR Green I Real-Time PCR in respect to the NDUFB8 gene. A putative up-regulation of PTEN protein was observed in TZD treated HeLa cells.

Genomic and phenomic correlations in the respiration of basal cell carcinomas

Early last century Warburg1 described differences in metabolism between normal and cancer cells, however subsequent research did not bear out what he considered to be the “primary cause of cancer,” i.e., the replacement of respiration by fermentation 2. Since then attention continues to periodically focus on analysis of the enzymology &/or energetics of oxygen metabolism in cancer cells. Despite such studies, there is still debate as to whether cancers shift towards aerobic metabolism or transform toward a more anaerobic metabolism3. While many theories were advanced to explain those findings, no consistent pattern emerged to correlate the changes observed across all cancers studied. Among many such studies was an investigation we carried out into the enzymology and isoenzymology of human non-melanotic skin cancers (NMSCs). In that research, the levels of three enzymes involved in glucose metabolism, namely lactate dehydrogenase (LDH), aldolase and glucose-6-phospshate dehydrogenase (G-6-PDH), were shown to be depressed in basal cell carcinoma tissue (BCC) compared to normal skin. By contrast, the level of another enzyme, NADP+-dependent isocitrate dehydrogenase was elevated. Those results confirmed the fmdings of Halprin’s group4. In further studies of the same material, the isoenzyme patterns of two of those enzymes were altered in BCC relative to normal skin. The changes seen in the LDH isoenzyme patterns, i.e. increases in the anionic species, were consistent with a shift to a more anaerobic metabolism as were the changes observed in aldolase. To further characterize the oxygen metabolism of BCC, the respiration of small volumes of tissue were directly measured using oxygen electrodes.

Analysis of Sdhd and Mmp12 in an Affected Solar Keratosis and Control Cohort

The incidence of Squamous Cell Carcinoma (SCG) is growing in certain populations to the extent that it is now the most common skin lesion in young men and women in high ultraviolet exposure regions such as Queensland. In terms of incidence up to 40% of the Australian population over 40 years of age is thought to possess the precancerous Solar Keratosis (SK) lesion and with a small, but significant, chance of progression into SCC, understanding the genetic events that play a role in this process is essential. The major aims of this study were to analyse whole blood derived samples for DNA aberrations in genes associated with tumour development and cellular maintenance, with the ultimate aim of identifying genes associated with non-melanoma skin cancer development. More specifically the first aim of this project was to analyse the SDHD and MMP12 genes via Dual-Labelled Probe Real-Time PCR for copy number aberrations in an affected Solar Keratosis and control cohort. It was found that 12 samples had identifiable copy-number aberrations in either the SDHD or MMP12 gene (this means that a genetic section of either of these two genes is aberrantly amplified or deleted), with five of the samples exhibiting aberrations in both genes. The significance of this study is the contribution to the knowledge of the genetic pathways that are malformed in the progression and development of the pre-cancerous skin lesion Solar Keratosis.

Focussing on Genomic and Phenomic Correlations in Respiration of Non-Melanotic Skin Cancers

In recent years, with the development of techniques in modem molecular biology, it has become possible to study the genetic basis of carcinogenesis down to the level of DNA sequence. Major advances have been made in our understanding of the genes involved in cell cycle control and descriptions of mutations in those genes. These developments have led to the definition of the role of specific oncogenes and tumour suppressor genes in several cancers, including, for example, colon cancers and some forms of breast cancer. Work reported from our laboratory has led to the identification of a number of candidate genes involved in the development of non-melanotic skin cancers. In this chapter, we attempt to further explain the observed (phenomic) alterations in metabolic pathways associated with oxygen consumption with the changes at the genetic level.