Colon cancer therapy: recent developments in nanomedicine to improve the efficacy of conventional chemotherapeutic drugs

The number of patients with colorectal cancer, the third most frequently diagnosed malignancy in the world, has increased markedly over the past 20 years and will continue to increase in the future. Despite recent advances in chemotherapy, currently used anticancer molecules are unable to improve the prognosis of advanced or recurrent colorectal cancer, which remains incurable. The transport of classical drugs by nanoparticles has shown great promise in terms of improving drug distribution and bioavailability, increasing tissue half-life and concentrating anticancer molecules in the tumor mass, providing optimal drug delivery to tumor tissue, and minimizing drug toxicity, including those effects associated with pharmaceutical excipients. In addition, colon cancer targeting may be improved by incorporating ligands for tumor-specific surface receptors. Similarly, nanoparticles may interact with key drug-resistance molecules to prevent a reduction in intracellular drug levels drug. Recently published data have provided convincing pre-clinical evidence regarding the potential of active-targeted nanotherapeutics in colon cancer therapy, although, unfortunately, only a few of these therapies have been translated into early-phase clinical trials. As nanotechnology promises to be a new strategy for improving the prognosis of colon cancer patients, it would be very useful to analyze recent progress in this field of research. This review discusses the current status of nanoparticle-mediated cancer-drug delivery, the challenges restricting its application, and the potential implications of its use in colon cancer therapy.

Abstract 623: Angiotensin Receptor Activation Contributes to Glucose Intolerance and Increased Insulin Resistance Independent of Elevated Systolic Blood Pressure, Adiposity and Dyslipidemia in a Model of Metabolic Syndrome

Activation of the renin-angiotensin system (RAS) leads to an increase in blood pressure and onset of insulin resistance (IR); however, the contributions of increased blood pressure and AT1 activation independently on the manifestation of IR are not well defined. The goal of this study was to determine the contribution of elevated blood pressure, independent of RAS, to the onset of IR in a model of metabolic syndrome. To address the hypothesis that AT1 activation, and not elevated blood pressure independently, is the principal contributor of obesity-associated IR, we measured changes in systolic blood pressure (SBP), adiposity, plasma triglycerides (TG), glucose tolerance, and insulin resistance index (IRI) in four groups of rats: 1) lean strain-control Long Evans Tokushima Otsuka (LETO; n=5), 2) obese Otsuka Long-Evans Tokushima Fatty (OLETF; n=7), 3) OLETF + angiotensin receptor blocker (ARB; 10 mg olmesartan/kg; n=8), and 4) OLETF + calcium channel blocker (CCB; 5 mg amlodipine/kg; n=7). ARB treatment alleviated the obesity-related increase in mean SBP, while the decrease with CCB remained 10.2 mmHg greater than LETO. ARB (0.51 g/100g body mass) and CCB (0.64 g/100g body mass) reduced mean relative retroperitoneal fat mass and mean plasma triglycerides (28.4 and 27.4 mg/dL respectively) compared to OLETF, but both remained greater (1.7, 1.57 g/100g body mass and 28.94, 29.94 mg/dL respectively) than LETO. ARB improved glucose tolerance by 4605.94 of 34965.94 and mean calculated IRI by 5581429.5 of 17398363, but CCB had no detectable effect on either. Despite relatively similar reductions in SBP, adiposity and plasma TG (principal components of metabolic syndrome), CCB did not improve glucose tolerance and IRI (additional metrics of metabolic syndrome), while ARB did, demonstrating that AT1 activation is the primary factor contributing to the development of impaired glucose metabolism and regulation during metabolic syndrome, independent of the hypertension, adiposity and dyslipidemia. Thus, targeting RAS to improve the consequences of metabolic syndrome appears to be prudent and effective.

Regulatory systems in bone marrow for hematopoietic stem/progenitor cells mobilization and homing

Regulation of hematopoietic stem cell release, migration, and homing from the bone marrow (BM) and of the mobilization pathway involves a complex interaction among adhesion molecules, cytokines, proteolytic enzymes, stromal cells, and hematopoietic cells. The identification of new mechanisms that regulate the trafficking of hematopoietic stem/progenitor cells (HSPCs) cells has important implications, not only for hematopoietic transplantation but also for cell therapies in regenerative medicine for patients with acute myocardial infarction, spinal cord injury, and stroke, among others. This paper reviews the regulation mechanisms underlying the homing and mobilization of BM hematopoietic stem/progenitor cells, investigating the following issues: (a) the role of different factors, such as stromal cell derived factor-1 (SDF-1), granulocyte colony-stimulating factor (G-CSF), and vascular cell adhesion molecule-1 (VCAM-1), among other ligands; (b) the stem cell count in peripheral blood and BM and influential factors; (c) the therapeutic utilization of this phenomenon in lesions in different tissues, examining the agents involved in HSPCs mobilization, such as the different forms of G-CSF, plerixafor, and natalizumab; and (d) the effects of this mobilization on BM-derived stem/progenitor cells in clinical trials of patients with different diseases.

How is gene transfection able to improve current chemotherapy? The role of combined therapy in cancer treatment

Despite advances in cancer treatment, a large number of patients eventually develop metastatic disease that is generally incurable. Systemic chemotherapy remains the standard treatment for these patients. Several chemotherapeutic combinations have proven effective in the management of cancer. Paradoxically, although the purpose of polychemotherapy is to improve the prognosis and prolong the survival of patients, it often carries considerable toxicity that causes substantial adverse symptoms. For this reason, a major goal of cancer research is to improve the effectiveness of these cytotoxic agents and reduce their adverse effects. Gene transfer has been proposed as a new strategy to enhance the efficacy of anti-tumor drugs in the treatment of intractable or metastatic cancers. In fact, the association of gene therapy and drugs (combined therapy) has been reported to increase the anti-proliferative effect of classical treatments in lung, bladder, pancreatic, colorectal and breast cancers, among others. Various especially promising therapies have been proposed in this context, including the use of suicide genes, antisense oligonucleotides, ribozymes and RNA interference. In this chapter, we review recent progress in the development of novel anti-cancer strategies that associate cytotoxic agents with gene transfer to enhance their antitumor effect.

Measuring higher-order modes in a low-loss, hollow-core, photonic-bandgap fiber

We perform detailed measurements of the higher-order-mode content of a low-loss, hollow-core, photonic-bandgap fiber. Mode content is characterized using Spatially and Spectrally resolved (S2) imaging, revealing a variety of phenomena. Discrete mode scattering to core-guided modes are measured at small relative group-delays. At large group delays a continuum of surface modes and core-guided modes can be observed. The LP11 mode is observed to split into four different group delays with different orientations, with the relative orientations preserved as the mode propagates through the fiber. Cutback measurements allow for quantification of the loss of different individual modes. The behavior of the modes in the low loss region of the fiber is compared to that in a high loss region of the fiber. Finally, a new measurement technique is introduced, the sliding-window Fourier transform of high-resolution transmission spectra of hollow-core fibers, which displays the dependence of HOM content on both wavelength and group delay. This measurement is used to illustrate the HOM content as function of coil diameter.

Tai chi diminishes oxidative stress in Mexican older adults

OBJECTIVE

To determine the effect of Tai Chi on oxidative stress in a population of elderly Mexican subjects.

DESIGN

It was carried out a quasi-experimental study with a sample of 55 healthy subjects randomly divided into two age-matched groups: (i) a control group with 23 subjects and (ii) an experimental group with 32 subjects. The experimental group received daily training in Tai Chi for 50 min.

MEASUREMENTS

It was measured before and after 6-month of exercise period: thiobarbituric acid reactive substances (TBARS), total antioxidant status (TAS), superoxide dismutase (SOD), and glutathione peroxidase (GPx).

RESULTS

It was found that the experimental group exhibited a statistically significant decrease in glucose levels, total cholesterol, low-density lipoprotein cholesterol (LDLC), and systolic blood pressure, as well as an increase in SOD and GPx activity and TAS compared with the control group (p < 0.05).

CONCLUSIONS

Our findings suggest that the daily practice of Tai Chi is useful for reducing OxS in healthy older adults.

The indication of tracheotomy conditions the predictors of time to decannulation in critical patients

OBJECTIVE

Variables predicting optimal timing for tracheostomy decannulation remain unknown. We aimed to determine whether classifying patients into two groups according to their indications for tracheostomy could identify variables associated with time to decannulation.

DESIGN

A prospective, observational cohort study was carried out.

LOCATION

Two medical-surgical ICUs.

PATIENTS

We included all patients tracheostomized during ICU stay, excluding patients with do-not-resuscitate orders, tracheostomies for long-term airway control, neuromuscular disease, or neurological damage. Patients were classified into two groups: patients tracheostomized due to prolonged weaning and/or prolonged mechanical ventilation (Group 1), and patients tracheostomized due to low level of consciousness or inability to manage secretions (Group 2).

INTERVENTIONS

Patients were weaned and decannulated according to established protocols.

MAIN VARIABLES

We recorded the following variables: time to tracheostomy, forced vital capacity, peak flow, suctioning requirements, Glasgow Coma Score (GCS), characteristics of respiratory secretions, and swallowing function. Statistical analyses included Cox-proportional multivariate analysis with time to decannulation as the dependent variable.

RESULTS

A total of 227 patients were tracheostomized in the ICUs; of these, 151 were finally included in the study. In the multivariate analysis, time to decannulation in Group 1 was associated with the male gender (HR 1.74 (1.04-2.89), p= 0.03), age>60 years (HR 0.58 (0.36-0.91), p= 0.02), high suctioning frequency (HR 0.81 (0.67-0.97), p= 0.02), low forced vital capacity (HR 0.48 (0.28-0.82), p<0.01), and low peak flow (HR 0.25 (0.14-0.46), p<0.01). In Group 2 time to decannulation was associated to GCS >13 (HR 2.73 (1.51-4.91), p<0.01), high suctioning frequency (HR 0.7 (0.54-0.91), p<0.01), and inadequate swallowing (HR 1.97 (1.11-3.52), p=0.02).

CONCLUSION

Variables associated with longer time to decannulation in ICU-tracheostomized patients differ with the indications for tracheostomy.

Retrospective analysis of pathologic response in colorectal cancer liver-only metastases following treatment with bevacizumab

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Background: Recent reports have shown that pathological response predicts for better outcome (overall survival) following preoperative chemotherapy and surgical resection of colorectal cancer (CRC) liver-only metastases. The aim of this retrospective analysis was to evaluate the effect of adding bevacizumab to standard chemotherapy on pathological response in patients with CRC liver only metastases.

Methods: Patients with stage IV CRC with liver metastases who received neoadjuvant chemotherapy (oxaliplatin-or irinotecan-based) at two Spanish centres were analysed retrospectively. Pathological response was evaluated as follows: complete pathological response (cPR), PR1 (25% of residual tumour), PR2 (25–50% of residual tumour), PR3 (>50% of residual tumour). cPR or PR1 was considered to be a good response, and PR2 or PR3 a poor response.

Results: A total of 81 patients were evaluated. Of these, 43 received chemotherapy alone and 38 received chemotherapy plus bevacizumab. Baseline characteristics were as follows: median age 61.0 years (range 43.0–80.0 years); male/female (67%/33%); tumour location – colon (69%) / rectum (31%); hepatic metastases – synchronous (74%) / metachronous (26%); In terms of pathological response, 58% of patients receiving bevacizumab had a good response (cPR + PR1) compared with 28% of those receiving chemotherapy alone. At the end of the analysis, 68% of patients were still alive.

Conclusions: Adding bevacizumab to oxaliplatin-based chemotherapy in the neoadjuvant setting improves the pathological response of liver metastases in patients with stage IV CRC. These findings indicate that pathological response might be a good indicator of outcome for patients receiving bevacizumab in the neoadjuvant setting.

Changes of the nucleolus architecture in absence of the nuclear factor CTCF

CTCF is a multifunctional nuclear factor involved in many cellular processes like gene regulation, chromatin insulation and genomic organization. Recently, CTCF has been shown to be involved in the transcriptional regulation of ribosomal genes and nucleolar organization in Drosophila cells and different murine cell types, including embryonic stem cells. Moreover, it has been suggested that CTCF could be associated to the nucleolus of human erythroleukemic K562 cells. In the present work, we took advantage of efficient small hairpin RNA interference against human CTCF to analyze nucleolar organization in HeLa cells. We have found that key components of the nucleolar architecture are altered. As a consequence of such alterations, an upregulation of ribosomal gene transcription was observed. We propose that CTCF contributes to the structural organization of the nucleolus and, through epigenetic mechanisms, to the regulation of the ribosomal gene expression.