Signaling in colon cancer stem cells

ABSTRACT: Colorectal cancer is the fourth most common form of cancer worldwide and ranks third among the cancer-related deaths in the US and other Western countries. It occurs with equal frequency in men and women, constituting 10 percent of new cancer cases in men and 11percent in women. Despite recent advancement in therapeutics, the survival rates from metastatic are less than 5 percent. Growing evidence supports the contention that epithelial cancers including colorectal cancer, the incidence of which increases with aging, are diseases driven by the pluripotent, self-renewing cancer stem cells (CSCs). Dysregulation of Wnt, Notch, Hedgehog and/or TGF-beta signaling pathways that are involved in proliferation and maintenance of CSCs leads to the development of CRC. This review focuses on the signaling pathways relevant for CRC to understand the mechanisms leading to tumor progression and therapy resistance, which may help in the development of therapeutic strategies for CRC.     

Racial disparity in colorectal cancer:Gut microbiome and cancer stem cells

Over the past two decades there has been remarkable progress in cancer diagnosis, treatment and screening. The basic mechanisms leading to pathogenesis of various types of cancers are also understood better and some patients, if diagnosed at a particular stage go on to lead a normal pre-diagnosis life. Despite these achievements, racial disparity in some cancers remains a mystery. The higher incidence, aggressiveness and mortality of breast, prostate and colorectal cancers(CRCs) in AfricanAmericans as compared to Caucasian-Americans are now well documented. The polyp-carcinoma sequence in CRC and easy access to colonic epithelia or colonic epithelial cells through colonoscopy/colonic effluent provides the opportunity to study colonic stem cells early in course of natural history of the disease. With the advent of metagenomic sequencing, uncultivable organisms can now be identified in stool and their numbers correlated with the effects on colonic epithelia. It would be expected that these techniques would revolutionize our understanding of the racial disparity in CRC and pave a way for the same in other cancers as well. Unfortunately, this has not happened. Our understanding of the underlying factors responsible in African-Americans for higher incidence and mortality from colorectal carcinoma remains minimal. In this review, we aim to summarize the available data on role of microbiome and cancer stem cells in racial disparity in CRC. This will provide a platform for further research on this topic.     

CD14 C-159T and early infection with Pseudomonas aeruginosa in children with cystic fibrosis

Early acquisition of Pseudomonas aeruginosa is associated with a poorer prognosis in patients with cystic fibrosis. We investigated whether polymorphisms in CD14, the lipopolysaccharide receptor, increase the risk of early infection. Forty-five children with cystic fibrosis were investigated with annual bronchoalveolar lavage (BAL) and plasma sCD14 levels. Plasma sCD14 levels were significantly lower in children from whom P.aeruginosa was subsequently isolated (492.75 μg/ml vs. 1339.43 μg/ml, p = 0.018). Those with the CD14 -159CC genotype had a significantly increased risk of early infection with P.aeruginosa suggesting that CD14 C-159T plays a role in determining the risk of early infection with P.aeruginosa.     

Direct cell-to-cell contact between Kupffer cells and hepatocytes augments endotoxin-induced hepatic injury

This study focuses on the importance of direct contact between Kupffer cells (KCs) and hepatocytes (HCs) during the hepatic inflammatory response using an in vitro approach. The lipopolysaccharide (LPS)-induced inflammatory response in monocultures of porcine HCs and KCs were compared with cocultures prepared either with direct contact between KCs and HCs (DC cocultures) or without direct contact using cell culture membrane inserts. Our data show that DC cocultures exhibited the highest production of tumor necrosis factor (TNF)-alpha, interleukin-6, and nitric oxide (NO) compared with the other cultures. Immunohistochemical studies revealed that TNF-alpha was exclusively produced by KCs, whereas HCs were responsible for NO production after LPS stimulation. Biotransformation capacity, as determined by cytochrome P-450 and UDP glucuronosyl transferase enzyme activities, was most significantly decreased in DC cocultures. These results provide evidence that direct contact between KCs and HCs favors the extensive TNF-alpha production by KCs but in turn affects HC functionality and viability. These findings suggest that direct contact between KCs and HCs plays a key role in the development of a fulminating hepatic inflammatory response.     

Chlamydia trachomatis Load in Population-Based Screening and STI-Clinics: Implications for Screening Policy

Objectives

If the Chlamydia trachomatis (CT) bacterial load is higher in high-risk populations than in the general population, this negatively affects the efficacy of CT screening incentives. In the largest retrospective study to date, we investigated the CT load in specimens collected from 2 cohorts: (1) attendants of a sexually transmitted infection (STI)-clinic and (2) participants of the Dutch population-based screening (PBS).

Methods

CT load was determined using quantitative PCR in CT-positive male urine and female cervicovaginal swabs. CT loads were converted into tertiles. Using multinominal logistic regression, independent association of cohort, symptoms, risk behaviour and human cell count on load were assessed.

Results

CT loads were determined in 889 CT-positives from PBS (n = 529; 71.8% female) and STI-clinics (n = 360; 61.7% female). In men, STI-clinic-cohort, human cell count and urethral discharge were positively associated with CT load. In women, PBS-cohort and cell count were positively associated with CT load. Both cohorts had the same range in CT load.

Conclusions

The general population has a similar range of bacterial CT load as a high-risk population, but a different distribution for cohort and gender, highlighting the relevance of population-based CT-screening. When CT loads are similar, possibly the chances of transmission and sequelae are too.     

High HIV Prevalence among Asylum Seekers Who Gave Birth in the Netherlands: A Nationwide Study Based on Antenatal HIV Tests

Objectives

Asylum seekers are considered to be a particularly vulnerable group with respect to HIV. Data on the HIV prevalence among asylum seekers, however, are scarce. The aim of this study is to map the HIV prevalence among asylum seekers who gave birth in The Netherlands.

Methods

We used a nationwide electronic medical records database from the community health services for asylum seekers (MOA). The study population consisted of 4,854 women and girls who delivered in asylum reception between 2000 and 2008. A unique electronic health data base was used and case allocation was based on ICPC-codes.

Results

The number of women and girls that was HIV positive during their last pregnancy was 80, of which 79 originated from sub-Saharan Africa. The prevalence for women from this region of origin (3.4%) was high compared to women from all other regions of origin (0.04%; OR = 90.2; 95%CI 12.5–648.8). The highest HIV prevalence rates were found for women from Rwanda (17.0%) and Cameroon (13.2%). HIV prevalence rates were higher among women who arrived in reception without partner (OR = 1.82; 95%CI 0.75–4.44) and unaccompanied minors (OR = 2.59; 95%CI 0.79–8.49), compared to women who arrived in reception with partner.

Conclusions

We conclude that, among asylum-seeking women from sub-Saharan Africa giving birth in The Netherlands, the HIV prevalence is high compared to the host population. For women from other regions of origin, the prevalence is at the same level as in the host population. The high HIV prevalence underlines the importance of preventive interventions and voluntary HIV testing for sub-Saharan African asylum seekers as from shortly after arrival.     

GIMAP5 Deficiency Is Associated with Increased AKT Activity in T Lymphocytes

Long-term survival of T lymphocytes in quiescent state is essential to maintain their cell numbers in secondary lymphoid organs. In mice and in rats, the loss of functional GTPase of the immune associated nucleotide binding protein 5 (GIMAP5) causes peripheral T lymphopenia due to spontaneous death of T cells. The underlying mechanism responsible for the disruption of quiescence in Gimap5 deficient T cells remains largely unknown. In this study, we show that loss of functional Gimap5 results in increased basal activation of mammalian target of rapamycin (mTOR), independent of protein phosphatase 2A (PP2A) or AMP-activated protein kinase (AMPK). Our results suggest that the constitutive activation of the phosphoinositide 3-kinase (PI3K) pathway may be one of the consequences of the absence of functional GIMAP5.     

Controlled light-exposure microscopy reduces photobleaching and phototoxicity in fluorescence live-cell imaging

Fluorescence microscopy of living cells enables visualization of the dynamics and interactions of intracellular molecules. However, fluorescence live-cell imaging is limited by photobleaching and phototoxicity induced by the excitation light. Here we describe controlled light-exposure microscopy (CLEM), a simple imaging approach that reduces photobleaching and phototoxicity two- to tenfold, depending on the fluorophore distribution in the object. By spatially controlling the light-exposure time, CLEM reduces the excitation-light dose without compromising image quality. We show that CLEM reduces photobleaching sevenfold in tobacco plant cells expressing microtubule-associated GFP-MAP4 and reduces production of reactive oxygen species eightfold and prolongs cell survival sixfold in HeLa cells expressing chromatin-associated H2B-GFP. In addition, CLEM increases the dynamic range of the fluorescence intensity at least twofold.     

Difference in volume of X- and Y-chromosome-bearing bovine sperm heads matches difference in DNA content.

BACKGROUND: To investigate the possibilities of sperm head volume as a sorting criterion for gender preselection, we determined the magnitude of the difference in volume of X- and Y-chromosome-bearing bull sperm heads. MATERIALS AND METHODS: Bovine sperm heads were sorted on the basis of their DNA content in X- and Y-chromosome-bearing fractions, using an existing flow-cytometric technique. Images of sperm heads of both populations were recorded using Differential Interference Contrast (DIC) microscopy. After reconstructing the DIC images, the area and the optical thickness of sperm heads of both populations were determined. RESULTS: We found a difference in volume of X- and Y-bearing bovine sperm heads matching the difference in DNA content (3.5-4%). CONCLUSIONS: Our findings indicate that volume can be used as a criterion to distinguish X- and Y-chromosome-bearing sperm, making development of a technique to sort X- and Y-chromosome-bearing sperm based on head volume theoretically possible. A strong advantage of such a technique over the existing technique based on DNA content would be that X- and Y-chromosome-bearing sperm cells could thus be sorted without subjecting them to any staining.     

The aged nonhematopoietic environment impairs natural killer cell maturation and function

Natural killer (NK) cells are critical in eliminating tumors and viral infections, both of which occur at a high incidence in the elderly. Previous studies showed that aged NK cells are less cytotoxic and exhibit impaired maturation compared to young NK cells. We evaluated whether extrinsic or intrinsic factors were responsible for the impaired maturation and function of NK cells in aging and whether impaired maturation correlated with functional hyporesponsiveness. We confirmed that aged mice have a significant decrease in the frequency of mature NK cells in all lymphoid organs. Impaired NK cell maturation in aged mice correlated with a reduced capacity to eliminate allogeneic and B16 tumor targets in vivo. This could be explained by impaired degranulation, particularly by mature NK cells of aged mice. Consistent with impaired aged NK cell maturation, expression of T‐bet and Eomes, which regulate NK cell functional maturation, was significantly decreased in aged bone marrow (BM) NK cells. Mixed BM chimeras revealed that the nonhematopoietic environment was a key determinant of NK cell maturation and T‐bet and Eomes expression. In mixed BM chimeras, NK cells derived from both young or aged BM cells adopted an ‘aged’ phenotype in an aged host, that is, were hyporesponsive to stimuli in vitro, while adopting a ‘young’ phenotype following transfer in young hosts. Overall, our data suggest that the aged nonhematopoietic environment is responsible for the impaired maturation and function of NK cells. Defining these nonhematopoietic factors could have important implications for improving NK cell function in the elderly.