Estrogens, phytoestrogens and colorectal neoproliferative lesions

Epidemiological and experimental studies suggest a protective role of estrogens against colorectal cancer. This effect seems to be mediated by their binding to estrogen receptor beta (ER-beta), one of the two estrogen receptors with high affinity for these hormones. Very recently, the demonstration of an involvement of ER-beta in the development of adenomatous polyps of the colon has also been documented, suggesting the use of selective ER-beta agonists in primary colorectal cancer prevention. Phytoestrogens are plant-derived compounds that structurally and functionally act as estrogen-agonists in mammals. They are characterized by a higher binding affinity to ER-beta as compared to estrogen receptor alpha (ER-alpha), the other estrogen receptor subtype. These biological characteristics explain why the administration of phytoestrogens does not produce the classical side effects associated to estrogen administration (cerebro- and cardio-vascular accidents, higher incidence of endometrial and breast cancer) and makes these substances ideal candidates for the prevention of colorectal cancer.     

Prognostic role of the CDNK1B V109G polymorphism in multiple endocrine neoplasia type 1

CDKN1B encodes the cyclin‐dependent kinase inhibitor p27/Kip1. CDKN1B mutations and polymorphisms are involved in tumorigenesis; specifically, the V109G single nucleotide polymorphism has been linked to different tumours with controversial results. Multiple endocrine neoplasia type 1 (MEN1) is a rare autosomal dominant syndrome, characterized by the development of different types of neuroendocrine tumours and increased incidence of other malignancies. A clear genotype–phenotype correlation in MEN1 has not been established yet. In this study, we assessed whether the CDKN1B V109G polymorphism was associated with the development of aggressive tumours in 55 consecutive patients affected by MEN1. The polymorphism was investigated by PCR amplification of germline DNA followed by direct sequencing. Baseline and follow‐up data of tumour types and their severity were collected and associated with the genetic data. MEN1‐related aggressive and other malignant tumours of any origin were detected in 16.1% of wild‐type and 33.3% of polymorphism allele‐bearing patients (P = NS). The time interval between birth and the first aggressive tumour was significantly shorter in patients with the CDKN1B V109G polymorphism (median 46 years) than in those without (median not reached; P = 0.03). Similarly, shorter was the time interval between MEN1 diagnosis and age of the first aggressive tumour (P = 0.02). Overall survival could not be estimated as 96% patients were still alive at the time of the study. In conclusion, CDKN1B V109G polymorphism seems to play a role in the development of aggressive tumours in MEN1.     

Polymerized and polyethylene glycol-conjugated hemoglobins: A globin-based calibration curve for dynamic light scattering analysis

Dynamic light scattering (DLS) is a technique capable of determining the hydrodynamic radius of proteins. From this parameter, a molecular weight can be assessed provided that an appropriate calibration curve is available. To this goal, a globin-based calibration curve was used to determine the polymerization state of a recombinant hemoglobin-based oxygen carrier and to assess the equivalent molecular weight of hemoglobins conjugated with polyethylene glycol molecules. The good agreement between DLS values and those obtained from gel filtration chromatography is a consequence of the high similarity in structure, shape, and density within the globin superfamily. Moreover, globins and heme proteins in general share similar spectroscopic properties, thereby reducing possible systematic errors associated with the absorption of the probe radiation by the chromophore.     

Time-resolved methods in Biophysics. 2. Monitoring haem proteins at work with nanosecond laser flash photolysis.

Haem proteins have long been the most studied proteins in biophysics, and have become paradigms for the characterization of fundamental biomolecular processes as ligand binding and regulatory conformational transitions. The presence of the haem prosthetic group, the absorbance spectrum of which has a ligation sensitive region conveniently located in the UV-visible range, has offered a powerful and sensitive tool for the investigation of molecular functions. The central Fe atom is capable of reversibly binding diatomic ligands, including O(2), CO, and NO. The Fe-ligand bond is photolabile, and a reactive unligated state can be transiently generated with a pulsed laser. The photodissociated ligands quickly rebind to the haem and the process can be monitored by transient absorbance methods. The ligand rebinding kinetics reflects protein dynamics and ligand migration within the protein inner cavities. The characterization of these processes was done in the past mainly by low temperature experiments. The use of silica gels to trap proteins allows the characterization of internal ligand dynamics at room temperature. In order to show the potential of the laser flash photolysis techniques, combined with modern numerical analysis methods, we report experiments conducted on two non-symbiotic haemoglobins from Arabidopsis thaliana. The comparison between time courses recorded on haemoglobins in solution and encapsulated in silica gels allows for the highlighting of different interplays between protein dynamics and ligand migration.     

Canine insulinoma as a model for human malignant insulinoma research: Novel perspectives for translational clinical studies

Insulinomas are considered rare indolent neuroendocrine neoplasms in human medicine, however when metastases occur no curative treatment is available thus, novel therapies are needed. Recently advances have been made in unraveling the pathophysiology of malignant insulinoma still major challenges hinder the development of a functional model to study them. Canine malignant insulinoma have similar recurrence and a poor prognosis as human malignant insulinoma. Additionally, both human and canine patients share extensively the same environment, tend to develop insulinoma seemingly spontaneously with an etiological role for hormones, at a similar incidence and stage of lifespan, with metastasis commonly to liver and regional lymph nodes, which are unresponsive to current therapies. However, the occurrence of metastases in dogs is as high as 95% compared with only 5–16% in human studies. From a comparative oncology perspective, the shared features with human insulinoma but higher incidence of metastasis in canine insulinoma suggests the latter as a model for human malignant insulinomas. With the common purpose of increasing survival rates of human and veterinary patients, in this review we are going to compare and analyze clinical, pathological and molecular aspects of canine and human insulinomas to evaluate the suitability of the canine model for future translational clinical studies.     

Towards the Personalized Treatment of Glioblastoma: Integrating Patient-Specific Clinical Data in a Continuous Mechanical Model

Glioblastoma multiforme (GBM) is the most aggressive and malignant among brain tumors. In addition to uncontrolled proliferation and genetic instability, GBM is characterized by a diffuse infiltration, developing long protrusions that penetrate deeply along the fibers of the white matter. These features, combined with the underestimation of the invading GBM area by available imaging techniques, make a definitive treatment of GBM particularly difficult. A multidisciplinary approach combining mathematical, clinical and radiological data has the potential to foster our understanding of GBM evolution in every single patient throughout his/her oncological history, in order to target therapeutic weapons in a patient-specific manner. In this work, we propose a continuous mechanical model and we perform numerical simulations of GBM invasion combining the main mechano-biological characteristics of GBM with the micro-structural information extracted from radiological images, i.e. by elaborating patient-specific Diffusion Tensor Imaging (DTI) data. The numerical simulations highlight the influence of the different biological parameters on tumor progression and they demonstrate the fundamental importance of including anisotropic and heterogeneous patient-specific DTI data in order to obtain a more accurate prediction of GBM evolution. The results of the proposed mathematical model have the potential to provide a relevant benefit for clinicians involved in the treatment of this particularly aggressive disease and, more importantly, they might drive progress towards improving tumor control and patient’s prognosis.     

Oxygen and nitric oxide rebinding kinetics in nonsymbiotic hemoglobin AHb1 from Arabidopsis thaliana

Type 1 nonsymbiotic hemoglobin from Arabidopsis thaliana (AHb1) shows a partial bis-histidyl hexacoordination but can reversibly bind diatomic ligands. The physiological function is still unclear, but the high oxygen affinity rules out a function related to O2 sensing, carrying, or storing. To gain insight into its possible functional roles, we have investigated its O2 and NO rebinding kinetics after laser flash photolysis. The rate constants of the rebinding from the primary docking site for both O2 and NO are higher than CO, with lower photolysis yields. Moreover, the amplitude of the geminate phase increases and, as for CO, the numerical analysis of the experimental curves suggests the existence of an internal pathway leading, with high rate, to an additional docking site. However, the accessibility to this site seems to be strongly ligand-dependent, being lower for O2 and higher for NO.