Molecular markers for diabetic nephropathy

Type 2 diabetes is one of the most common metabolic disorders in the world. Globally, the prevalence of this disorder is predicted to increase, along with the risk of developing diabetic related complications. One of those complications is diabetic nephropathy, defined by a progressive increase in proteinuria and a gradual decline in renal function. Approximately 25% to 30% of type 2 diabetic individuals develop this complication. However, its underlying genetic mechanisms remain unclear. Thus, the aim of this study is to contribute to the discovery of the genetic mechanisms involved in the development and progression of diabetic nephropathy, through the identification of relevant genetic variants in Portuguese type 2 diabetic individuals. The exomes of 36 Portuguese type 2 diabetic individuals were sequenced on the Ion ProtonTM Sequencer. From those individuals, 19 did not present diabetic nephropathy, being included in the control group, while the 17 individuals that presented the diabetic complication formed the case group. A statistical analysis was then performed to identify candidate common genetic variants, as well as genes accumulating rare variants that could be associated with diabetic nephropathy. From the search for common variants in the study population, the statistically significant (p-value ≤ 0.05) variants rs1051303 and rs1131620 in the LTBP4 gene, rs660339 in UCP2, rs2589156 in RPTOR, rs2304483 in the SLC12A3 gene and rs10169718 present in ARPC2, were considered as the most biologically relevant to the pathogenesis of diabetic nephropathy. The variants rs1051303 and rs1131620, as well as the variants rs660339 and rs2589156 were associated with protective effects in the development of the complication, while rs2304483 and rs10169718 were considered risk variants, being present in individuals with diagnosed diabetic nephropathy. In the rare variants approach, the genes with statistical significance (p-value ≤ 0.05) found, the STAB1 gene, accumulating 9 rare variants, and the CUX1 gene, accumulating 2 rare variants, were identified as the most relevant. Both genes were considered protective, with the accumulated rare variants mainly present in the group without the renal complication. The present study provides an initial analysis of the genetic evidence associated with the development and progression of diabetic nephropathy, and the results obtained may contribute to a deeper understanding of the genetic mechanisms associated with this diabetic complication.

From genes to radioresistance in head and neck squamous cell carcinoma

Head and Neck Cancers (HNC) are a group of tumours located in the upper aero-digestive tract. Head and Neck Squamous Cell Carcinoma (HNSCC) represent about 90% of all HNC cases. It has been considered the sixth most malignant tumour worldwide and, despite clinical and technological advances, the five-year survival rate has not improved much in the last years. Nowadays, HNSCC is well established as a heterogeneous disease and that its development is due to accumulation of genetic events. Apart from the majority of the patients being diagnosed in an advanced stage, HNSCC is also a disease with poor therapeutic outcome. One of the therapeutic approaches is radiotherapy. However, this approach has different drawbacks like the radioresistance acquired by some tumour cells, leading to a worse prognosis. A major knowledge in radiation biology is imperative to improve this type of treatment and avoid late toxicities, maintaining patient quality of life in the subsequent years after treatment. Then, identification of genetic markers associated to radiotherapy response in patients and possible alterations in cells after radiotherapy are essential steps towards an improved diagnosis, higher survival rate and a better life quality. Not much is known about the radiation effects on cells, so, the principal aim of this study was to contribute to a more extensive knowledge about radiation treatment in HNSCC. For this, two commercial cell lines, HSC-3 and BICR-10, were used and characterized resorting to karyotyping, aCGH and MS-MLPA. These cell lines were submitted to different doses of irradiation and the resulting genetic and methylation alterations were evaluated. Our results showed a great difference in radiation response between the two cell lines, allowing the conclusion that HSC-3 was much more radiosensitive than BICR-10. Bearing this in mind, analysis of cell death, cell cycle and DNA damages was performed to try to elucidate the motifs behind this difference. The characterization of both cell lines allowed the confirmation that HSC-3 was derived from a metastatic tumour and the hypothesis that BICR-10 was derived from a dysplasia. Furthermore, this pilot study enabled the suggestion of some genetic and epigenetic alterations that cells suffer after radiation treatment. Additionally, it also allowed the association of some genetic characteristics that could be related to the differences in radiation response observable in this two cell lines. Taken together all of our results contribute to a better understanding of radiation effects on HNSCC allowing one further step towards the prediction of patients’ outcome, better choice of treatment approaches and ultimately a better quality of life.