Challenges to cancer control by screening

Investigation of adhesive interactions in the specific targeting of Triptorelin-conjugated PEG-coated magnetite nanoparticles to breast cancer cells

The understanding of adhesive interaction at the nanoscale between functionalized nanoparticles and biological cells is of great importance to develop effective theranostic nanocarriers for targeted cancer therapy. Here, we report a combination of experimental and computational approaches to evaluate the adhesion between Triptorelin (a Luteinizing Hormone-Releasing Hormone (LHRH) agonist)-conjugated poly-(ethylene glycol) (PEG)-coated magnetite nanoparticles (Triptorelin-MNPs) and breast cells. The adhesion forces between Triptorelin-MNPs and normal/cancerous breast cells are obtained using atomic force microscopy. The corresponding work of adhesion is then estimated using Johnson-Kendall-Roberts model. Our results demonstrate that Triptorelin-MNPs have a fourteen-fold greater work of adhesion to breast cancer cells than to normal breast cells. In addition, the work of adhesion between Triptorelin-MNPs and breast cancer cells is found to be three times more than that between unmodified MNPs and breast cancer cells. Hence, the experimental observation indicates that Triptorelin ligands facilitate the specific targeting of breast cancer cells. Furthermore, molecular dynamics simulations are performed to investigate the molecular origins of the adhesive interactions. The simulations reveal that the interactions between molecules (e.g. Triptorelin and PEG) and LHRH receptors are dominated by van der Waals energies, while the interactions of these molecules with cell membrane are dominated by electrostatic interactions. Moreover, both experimental and computational results reveal that PEG serves as an effective coating that enhances adhesive interactions to breast cancer cells that over-express LHRH receptors, while reduces the adhesion to normal breast cells. Our results highlight the potential to develop Triptorelin-MNPs into tumor-specific MRI contrast agents and drug carriers.

STATEMENT OF SIGNIFICANCE

Systematic investigation of adhesive interactions between functionalized nanoparticles and cancer cells is of great importance in developing effective theranostic nanocarriers for targeted cancer therapy. Herein, we use a combination of atomic force microscopy technique and molecular dynamics simulations approach to explore the adhesive interactions at the nanoscale between Triptorelin-conjugated polyethylene glycol (PEG)-coated magnetite nanoparticles and normal/cancerous breast cells. This study characterizes and quantifies the work of adhesion, as well as adhesion forces, at the nanocarrier/cell interfaces, unravels the molecular origins of adhesive interactions and highlights the effectiveness of PEG coatings and Triptorelin ligands in the specific targeting of breast cancer cells. Our findings expand the fundamental understanding of nanoparticle/cell adhesion and provide guidelines for the design of more rational nanocarriers.

Low-mass-ion discriminant equation: a new concept for colorectal cancer screening

Blood metabolites can be detected as low-mass ions (LMIs) by mass spectrometry (MS). These LMIs may reflect the pathological changes in metabolism that occur as part of a disease state, such as cancer. We constructed a LMI discriminant equation (LOME) to investigate whether systematic LMI profiling might be applied to cancer screening. LMI information including m/z and mass peak intensity was obtained by five independent MALDI-MS analyses, using 1,127 sera collected from healthy individuals and cancer patients with colorectal cancer (CRC), breast cancer (BRC), gastric cancer (GC) and other types of cancer. Using a two-stage principal component analysis to determine weighting factors for individual LMIs and a two-stage LMI selection procedure, we selected a total of 104 and 23 major LMIs by the LOME algorithms for separating CRC from control and rest of cancer samples, respectively. CRC LOME demonstrated excellent discriminating power in a validation set (sensitivity/specificity: 93.21%/96.47%). Furthermore, in a fecal occult blood test (FOBT) of available validation samples, the discriminating power of CRC LOME was much stronger (sensitivity/specificity: 94.79%/97.96%) than that of the FOBT (sensitivity/specificity: 50.00%/100.0%), which is the standard CRC screening tool. The robust discriminating power of the LOME scheme was reconfirmed in screens for BRC (sensitivity/specificity: 92.45%/96.57%) and GC (sensitivity/specificity: 93.18%/98.85%). Our study demonstrates that LOMEs might be powerful noninvasive diagnostic tools with high sensitivity/specificity in cancer screening. The use of LOMEs could potentially enable screening for multiple diseases (including different types of cancer) from a single sampling of LMI information.

Aptamer--nanoparticle-based chemiluminescence for p53 protein

A simple colorimetric biosensing technique based on the interaction of gold nanoparticles (AuNPs) with the aptamer was developed for detection of p53, a tumor suppressor protein, in the current study. Aggregation of AuNPs was induced by desorption of the p53 binding RNA aptamer from the surface of AuNPs as a result of the aptamer target interaction leading to the color change of AuNPs from red to purple. The detection limit of p53 protein by the colorimetric approach was 0.1 ng/ml after successful optimization of the amount of aptamer, AuNPs, salts, and incubation time. Furthermore, the catalytic activity of the aggregated AuNPs was greatly enhanced by chemiluminescence (CL) reaction, where the detection limit was enhanced to 10 pg/ml with a regression coefficient of R2 = 0.9907. Here the sensitivity was increased by 10-fold compared with the AuNP-based colorimetric method. Hence, the sensitivity of detection was increased by employing CL, by using the catalytic activity of aggregated AuNPs, on the luminol-hydrogen peroxide reaction. Thus, the combination of colorimetric and CL-based aptasensor can be of great advantage in increasing the sensitivity of detection for any target analyte.

A novel measure of dietary change in a prostate cancer dietary program incorporating mindfulness training

Diet may represent a modifiable prostate cancer risk factor, but a vegetable-based prostate-healthy diet is a major change for most men. We used a ratio of animal to vegetable proteins (A:V) to evaluate whether a comprehensive dietary change was self-sustaining following completion of 11 weekly dietary and cooking classes that integrated mindfulness training. Thirty-six men with recurring prostate cancer were randomized to the intervention or wait-list control. Assessments were at baseline, 3 months, and 6 months. Of 17 men randomized to the intervention, 14 completed the requirements. Nineteen were randomized to control and 17 completed requirements. Compared with controls, a significant postintervention (3 months) decrease in A:V in the intervention group (P=0.01) was self-maintained 3 months postintervention (P=0.049). At each assessment, A:V was correlated with lycopene, fiber, saturated fat, and dietary cholesterol, four dietary components linked to clinically relevant outcomes in prostate cancer. Change in A:V was also significantly correlated with changes in fiber, saturated fat, and dietary cholesterol intake. Participants reported regular mindfulness training practice, and there was a significant correlation between mindfulness training practice and changes in both initiation and maintenance of the change in A:V. These pilot results provide encouraging evidence for the feasibility of a dietary program that includes mindfulness training in supporting dietary change for men with recurrent prostate cancer and invite further study to explore the possible role of mindfulness training as a means of supporting both initiation of dietary changes and maintenance of those changes over time.

Screening for cancer with molecular markers: progress comes with potential problems

Recent research has raised hopes for impressively accurate screening for cancer with molecular biomarkers. These molecular markers will probably be more sensitive and specific than older screening modalities, as well as easier to use. In this Essay, I argue that these sensitive screening tests might be clinically valuable - but that they will present unique issues in implementation and interpretation. These issues are likely to affect the way clinicians conduct screening and the way that they make diagnoses in individuals who screen positive for cancer.

A color discriminating broad range cell staining technology for early detection of cell transformation

BACKGROUND

Advanced diagnostic tools stand today at the heart of successful cancer treatment. CellDetect(R) is a new histochemical staining technology that enables color discrimination between normal cells and a wide variety of neoplastic tissues. Using this technology, normal cells are colored blue/green, while neoplastic cells color red. This tinctorial difference coincides with clear morphological visualization properties, mainly in tissue samples. Here we show that the CellDetect(R) technology can be deployed to distinguish normal cells from transformed cells and most significantly detect cells in their early pre-cancerous transformed state.

MATERIALS AND METHODS

In tissue culture, we studied the ability of the CellDetect(R) technology to color discriminate foci in a number of two stage transformation systems as well as in a well defined cellular model for cervical cancer development, using HPV16 transformed keratinocytes.

RESULTS

In all these cellular systems, the CellDetect(R) technology was able to sensitively show that all transformed cells, including pre-cancerous HPV 16 transformed cells, are colored red, whereas normal cells are colored blue/green. The staining technology was able to pick up: (i) early transformation events in the form of small type 1 foci (non-invasive, not piled up small, with parallel alignment of cells), and (ii) early HPV16 transformed cells, even prior to their ability to form colonies in soft agar. The study shows the utility of the CellDetect(R) technology in early detection of transformation events.

Biomarkers in oncology research and treatment: early detection research network: a collaborative approach

Several important criteria are essential for the development of biomarkers in clinical oncology. First, the biomarkers should be easily measured using standardized and cost-efficient methods. Second, biomarkers should be easily attainable from clinical materials such as body fluids and cells. Third, biomarkers should have clearly defined cutoff values with high sensitivity and specificity. Lastly, the predictive value of biomarkers should be possible in strata as large as possible. Single biomarkers may not be able to meet all of these criteria, which necessitates the development of biomarker panels. High-throughput technologies will be necessary for measuring these biomarker sets and translation of these methods into a clinical setting will be necessary in order to employ these biomarkers in a healthcare setting. One of the most important aspects of biomarker development will be standardization and statistical evaluation of biomarker studies. Guidelines for biomarker studies need to be developed that will enable standardization to take place. The Early Detection Research Network has been in the forefront of this objective. Early detection of cancer through appropriately validated biomarkers will provide for decreased morbidity and mortality and allow for the development of new therapeutic tools targeted specifically toward eradication of these early malignancies, hopefully increasing the survival rate of patients diagnosed with early-stage cancer.

Quantifying the role of PSA screening in the US prostate cancer mortality decline

OBJECTIVE

To quantify the plausible contribution of prostate-specific antigen (PSA) screening to the nearly 30% decline in the US prostate cancer mortality rate observed during the 1990s.

METHODS

Two mathematical modeling teams of the US National Cancer Institute's Cancer Intervention and Surveillance Modeling Network independently projected disease mortality in the absence and presence of PSA screening. Both teams relied on Surveillance, Epidemiology, and End Results (SEER) registry data for disease incidence, used common estimates of PSA screening rates, and assumed that screening, by shifting disease from distant to local-regional clinical stage, confers a corresponding improvement in disease-specific survival.

RESULTS

The teams projected similar mortality increases in the absence of screening and decreases in the presence of screening after 1985. By 2000, the models projected that 45% (Fred Hutchinson Cancer Research Center) to 70% (University of Michigan) of the observed decline in prostate cancer mortality could be plausibly attributed to the stage shift induced by screening.

CONCLUSIONS

PSA screening may account for much, but not all, of the observed drop in prostate cancer mortality. Other factors, such as changing treatment practices, may also have played a role in improving prostate cancer outcomes.

Recent advances in biomarkers for cancer diagnosis and treatment

With the availability of new technologies and the increased interest of medical practitioners to use molecular biomarkers in early detection and diagnosis, and in the prediction of therapeutic treatment efficacy and clinical outcomes, the academic and research institutions, as well as the pharmaceutical industry, have increased their efforts to develop novel molecular biomarkers for several human diseases, including cancer. The identification of molecular biomarkers also enables the development of a new generation of diagnostic products and to integrate diagnostics and therapeutics. This integrated approach will aid in 'individualizing' the medical practice. Here, we address issues related to the development of biomarkers, novel technological platforms used for drug development, future technologies and strategies for validating biomarkers for their clinical utility.

Individualizing interventions for cancer prevention

Many cancer prevention strategies are unlikely to provide equal risk reduction in all subjects, but instead are predicted to be particularly useful for specific individuals. An important research challenge is to devise methods for individualization of cancer prevention recommendations, such that particular interventions are assigned to those who will gain the most. Research in this area is at an early stage, but progress that allows rational assignment of specific prevention strategies to particular individuals who will benefit would decrease the cost, minimize the toxicity, and increase the efficacy of interventions intended to prevent cancer.

The potential of optical coherence tomography in the engineering of living tissue

The better repair of human tissue is an urgent medical goal and in order to achieve a safe outcome there is a parallel need for sensitive, non-invasive methods of assessing the quality of the engineered tissues and organs prior to surgical implantation. Optical coherence tomography (OCT) can potentially fulfil this role. The current status of OCT as an advanced imaging tool in clinical medicine, developmental biology and material science is reviewed and the parallels to the engineering of living tissue and organs are discussed. Preliminary data are also presented for a tissue engineering bioreactor with in situ OCT imaging. The data suggest that OCT can be utilized as a real time, non-destructive, non-invasive tool to critically monitor the morphology of tissue-engineered constructs during their fabrication and growth.