Possible Gender-Related Modulation by the ROCK1 Gene in Colorectal Cancer Susceptibility

AIM

In view of accumulating evidence supporting a pivotal role of the Rho/ROCK pathway in cancer, we investigated Rho-kinase polymorphisms as potential susceptibility factors in colorectal cancer (CRC) in a representative sample of the Italian population.

METHODS

DNA obtained from the peripheral blood samples of 137 CRC patients and 141 healthy controls was genotyped for four ROCK1 (rs35996865; rs73963110; rs2127958; rs288980) and five ROCK2 (rs12692437; rs7563468; rs35768389; rs17463896; rs16857265) selected single nucleotide polymorphisms.

RESULTS

None of the allelic variants of the nine selected markers was associated with the occurrence of CRC or with the development of regional lymph node metastasis. By contrast, the ROCK1 rs35996865 G variant allele was significantly more frequent in male patients (p = 0.028) than in the control group.

CONCLUSION

This finding is, at present, the first that points to a possible gender-related modulation by the ROCK1 gene in CRC susceptibility.

The nano-epsilon dot method for strain rate viscoelastic characterisation of soft biomaterials by spherical nano-indentation

Nano-indentation is widely used for probing the micromechanical properties of materials. Based on the indentation of surfaces using probes with a well-defined geometry, the elastic and viscoelastic constants of materials can be determined by relating indenter geometry and measured load and displacement to parameters which represent stress and deformation. Here we describe a method to derive the viscoelastic properties of soft hydrated materials at the micro-scale using constant strain rates and stress-free initial conditions. Using a new self-consistent definition of indentation stress and strain and corresponding unique depth-independent expression for indentation strain rate, the epsilon dot method, which is suitable for bulk compression testing, is transformed to nano-indentation. We demonstrate how two materials can be tested with a displacement controlled commercial nano-indentor using the nano-espilon dot method (nano-ε̇M) to give values of instantaneous and equilibrium elastic moduli and time constants with high precision. As samples are tested in stress-free initial conditions, the nano-ε̇M could be useful for characterising the micro-mechanical behaviour of soft materials such as hydrogels and biological tissues at cell length scales.

Profile analysis of hepatic porcine and murine brain tissue slices obtained with a vibratome

This study is aimed at characterizing soft tissue slices using a vibratome. In particular, the effect of two sectioning parameters (i.e., step size and sectioning speed) on resultant slice thickness was investigated for fresh porcine liver as well as for paraformaldehyde-fixed (PFA-fixed) and fresh murine brain. A simple framework for embedding, sectioning and imaging the slices was established to derive their thickness, which was evaluated through a purposely developed graphical user interface. Sectioning speed and step size had little effect on the thickness of fresh liver slices. Conversely, the thickness of PFA-fixed murine brain slices was found to be dependent on the step size, but not on the sectioning speed. In view of these results, fresh brain tissue was sliced varying the step size only, which was found to have a significant effect on resultant slice thickness. Although precision-cut slices (i.e., with regular thickness) were obtained for all the tissues, slice accuracy (defined as the match between the nominal step size chosen and the actual slice thickness obtained) was found to increase with tissue stiffness from fresh liver to PFA-fixed brain. This quantitative investigation can be very helpful for establishing the most suitable slicing setup for a given tissue.

Human Multidrug Resistance 1 gene polymorphisms and Idiopathic Pulmonary Fibrosis

BACKGROUND

For the first time we tested an association between the human multidrug resistance gene 1 (MDR1) polymorphisms (SNPs) and idiopathic pulmonary fibrosis (IPF). Several MDR1 polymorphisms are associated with pathologies in which they modify the drug susceptibility and pharmacokinetics.

MATERIALS AND METHODS

We genotyped three MDR1 polymorphisms of 48 IPF patients and 100 control subjects with Italian origins.

RESULTS

No evidence of association was detected.

CONCLUSION

There are 50 known MDR1 SNPs, and their role is explored in terms of the effectiveness of drug therapy. We consider our small-scale preliminary study as a starting point for further research.

Strain rate viscoelastic analysis of soft and highly hydrated biomaterials

Measuring the viscoelastic behavior of highly hydrated biological materials is challenging because of their intrinsic softness and labile nature. In these materials, it is difficult to avoid prestress and therefore to establish precise initial stress and strain conditions for lumped parameter estimation using creep or stress-relaxation (SR) tests. We describe a method ( ɛ˙M or epsilon dot method) for deriving the viscoelastic parameters of soft hydrated biomaterials which avoids prestress and can be used to rapidly test degradable samples. Standard mechanical tests are first performed compressing samples using different strain rates. The dataset obtained is then analyzed to mathematically derive the material's viscoelastic parameters. In this work a stable elastomer, polydimethylsiloxane, and a labile hydrogel, gelatin, were first tested using the ɛ˙M, in parallel SR was used to compare lumped parameter estimation. After demonstrating that the elastic parameters are equivalent and that the estimation of short-time constants is more precise using the proposed method, the viscoelastic behavior of porcine liver was investigated using this approach. The results show that the constitutive parameters of hepatic tissue can be quickly quantified without the application of any prestress and before the onset of time-dependent degradation phenomena.

Local-field enhancement effect on the nonlinear optical response of gold-silver nanoplanets

We report on the nonlinear optical properties of Au-Ag nanoplanets produced by ion implantation and irradiation in silica, experimentally investigated by means of the single beam z-scan technique. The measurements provided experimental evidence of the intense local-field enhancement effect theoretically demonstrated for these plasmonic nanosystems. In particular, this has a dramatic impact on their nonlinear absorption behavior and results in a tunable changeover from reverse saturable absorption to saturable absorption by slightly varying the pump intensity and in the possibility to activate and observe nonlinear phenomena of the electron dynamics otherwise unaccessible in the intensity range that can be employed to study these materials. Finally, for the nanoplanet configuration we found a dramatic decrease of the intensity-dependent absorption coefficient, which could be very promising for obtaining optical gain materials.

The EGFR R521K polymorphism influences the risk to develop colorectal cancer

Epidermal growth factor receptor (EGFR) family members (EGFR, HER2, HER3 and HER4) have been extensively investigated for its possible involvement in cancer development and progression. In colorectal cancer (CRC) EGFR family has been found frequently over-expressed, thus therapy targeting EGFR has been developed. Interestingly, it has been observed that genetic variants in these receptors may alter the therapeutic efficacy of EGFR inhibitors. Polymorphic variants in members of the EGFR family could influence different biologic activities, such as ligands affinity, dimerization efficiency, kinase activity, expression levels, with a consequent impact in signalling pathways and cell behaviour. This study aimed to verify whether single nucleotide polymorphisms (SNPs) of EGFR family members could represent susceptibility factors able to influence the risk to develop CRC. Peripheral blood of 70 Italian colon cancer patients and 72 healthy controls was used as a source of genomic DNA to investigate EGFR, HER2 and HER3 common non-synonymous SNPs. Genetic association tests were performed to verify a possible relationship with CRC. Evidence of genotype association was found for the R521K EGFR polymorphism under a dominant mode of inheritance (Mid-P=0.031). Genotypes with the variant allele of EGFR R521K SNP confer a risk reduction to develop CRC.

Gene expression profile of human colon cancer cells treated with cross-reacting material 197, a diphtheria toxin non-toxic mutant

Cross-Reacting Material 197 (CRM197) is a diphtheria toxin non-toxic mutant that has shown antitumor activity in mice and humans. It is still unclear whether this anti-tumorigenic effect depends on its strong inflammatory-immunological property, its ability to inhibit heparin-binding epidermal growth factor (HB-EGF), or even its possible weak toxicity. CRM197 is utilized as a specific inhibitor of HB-EGF that competes for the epidermal growth factor receptor (EGFR), overexpressed in colorectal cancer and implicated in its progression. In this study we evaluate the effects of CRM197 on HT-29 human colon cancer cell line behaviour and, for CRM197 recognized ability to inhibit HB-EGF, its possible influence on EGFR activation. In particular, while HT-29 does not show any reduction of viability after CRM197 treatment (MTT modified assay), or changes in cell cycle distribution (flow cytometry), in EGFR localization, phospho-EGFR detected signals (immunohistochemistry) or in morphology (scanning electron microscopy, SEM) they show a change in the gene expression profile by microarray analysis (cDNA microarray SS-H19k8). The overexpression of genes like protein phosphatase 2, catalytic subunit, alpha isozyme (PPP2CA), guanine nucleotide-binding protein G subunit alpha-1(GNAI1) and butyrophilin, subfamily 2, member A1 (BTN2A1) has been confirmed with real-time-qPCR. This is the first study where the CRM197 treatment on HT-29 shows a possible scarce implication of endogenous HB-EGF on EGFR expression and cancer cell development. At the same time, our results show the alteration of a specific and selected number of genes.