Elucidation of the anticancer potential and tubulin isotype-specific interactions of β-sitosterol

Beta-sitosterol (β-SITO), a phytosterol present in many edible vegetables, has been reported to possess antineoplastic properties and cancer treatment potential. We have shown previously that it binds at a unique site (the ‘SITO-site’) compared to the colchicine binding site at the interface of α- and β-tubulin. In this study, we investigated the anticancer efficacy of β-SITO against invasive breast carcinoma using MCF-7 cells. Since ‘isotypes’ of β-tubulin show tissue-specific expression and many are associated with cancer drug resistance, using computer-assisted docking and atomistic molecular dynamic simulations, we also examined its binding interactions to all known isotypes of β-tubulin in αβ-tubulin dimer. β-SITO inhibited MCF-7 cell viability by up to 50%, compared to vehicle-treated control cells. Indicating its antimetastatic potential, the phytosterol strongly inhibited cell migration. Immunofluorescence imaging of β-SITO-treated MCF-7 cells exhibited disruption of the microtubules and chromosome organization. Far-UV circular dichroism spectra indicated loss of helical stability in tubulin when bound to β-SITO. Docking and MD simulation studies, combined with MM-PBSA and MM-GBSA calculations revealed that β-SITO preferentially binds with specific β-tubulin isotypes (β_II and β_III) in the αβ-tubulin dimer. Both these β-tubulin isotypes have been implicated in drug resistance against tubulin-targeted chemotherapeutics. Our data show the tubulin-targeted anticancer potential of β-SITO, and its potential clinical utility against β_II and β_III isotype-overexpressing neoplasms.     

Stimulatory effects of Cuminum cyminum and flavonoid glycoside on Cyclosporine-A and restraint stress induced immune-suppression in Swiss albino mice

Many herbs and spices are known to modulate the immune system and have been shown to restore the immunity in immuno-compromised individuals. Spices generally used to increase the taste and flavor of food also has the history of usage as an ayurvedic medicine. Therefore to explore the health modulating effects of Cuminum cyminum and to identify the active compound, immunomodulatory properties were evaluated using flowcytometry and ELISA in normal and immune-suppressed animals. C. cyminum and compound 1 stimulated the T cells and Th1 cytokines expression in normal animals. Swiss albino mice subjected to Cyclosporine-A induced immune-suppression were dosed orally with C. cyminum (25, 50, 100 and 200 mg/kg) on consecutive days. The results showed that administration significantly increased T cells (CD4 and CD8) count and Th1 predominant immune response in a dose dependent manner thereby suggesting immunomodulatory activity through modulation of T lymphocytes expression. In restraint stress induced immune-suppressed animals, compound 1 countered the depleted T lymphocytes, decreased the elevated corticosterone levels and size of adrenal glands and increased the weight of thymus and spleen. Based on the data we may conclude that C. cyminum is a potent immunomodulator and may develop as a lead to recover the immunity of immuno-compromised individuals.     

Genetic variation in BDNF is associated with allergic asthma and allergic rhinitis in an ethnic Chinese population in Singapore

Allergic diseases affect more than 25% of the world population and result from a complex interplay between genetic and environmental factors. Recent evidence has shown that BDNF (Brain Derived Neurotrophic Factor) could serve as an important marker of allergic disease. Increased levels of BDNF in blood, bronchoalveolar lavage fluid and nasal lavage fluid positively correlate with disease activity and severity in patients with allergic rhinitis (AR), asthma and atopic eczema. However, reports on the association between genetic variation in BDNF and allergic disease have been controversial. This study therefore aims to clarify the relationship between single nucleotide polymorphisms (SNPs) in BDNF and a genetic predisposition to AR and asthma in an ethnic Chinese population of Singapore. Volunteers with a self-reported history of asthma (718 subjects) or a history of AR as determined by a researcher-administered questionnaire (795 subjects) were used in this study, alongside controls with no personal or family history of allergy (717 subjects). The association results identified a significant association for the tagSNP rs10767664 with a significant P_Dominant = 0.0007 and OR = 1.3 for AR and P_Dominant = 0.0005 and OR = 1.3 for asthma (using a dominant model of association). The haplotype based analysis also identified a significant association further confirming the single SNP association. The SNP rs10767664 is strongly linked (r² = 0.95) to the functional polymorphism rs6265 (Val66Met), which has previously been reported to be associated to allergic phenotypes and also shown to affect BDNF expression. BDNF is a therefore a key molecular player in allergy. Further studies on polymorphisms within BDNF may shed light on its role in the pathogenesis of allergic diseases and potentially serve as biomarkers for allergic disease.     

Predictive Factors of Late Venous Aortocoronary Graft Failure: Ultrastructural Studies

Background

Venous aortocoronary graft arterialization may precede a preterm occlusion in some coronary artery bypass grafting (CABG) patients. The aim of the present study was to identify ultrastructural variations in the saphenous vein wall that may have an impact on the development of venous graft disease in CABG patients.

Methods

The study involved 365 consecutive patients with a mean age of 62.9±9.4 years who underwent isolated CABG. The thickness and area of the whole venous wall, the tunica intima, the tunica media and the adventitia and the number and shape (length, thickness and length/thickness ratio) of the nuclei in the medial smooth muscle cells nuclei in the distal saphenous vein segments were evaluated by ultrastructural studies. Patients were followed up for 41 to 50 months (mean 45.1±5.1). Saphenous vein graft patency was assessed by follow-up coronary angiography. Logistic regression models were used to identify independent risk factors for late graft failure.

Results

In 71 patients significant lesions in the saphenous vein grafts were observed. The whole venous wall thickness (437.5 µm vs. 405.5 µm), tunica media thickness (257.2 µm vs. 211.5 µm), whole venous wall area (2.23 mm² vs. 2.02 mm²) and tunica media area (1.09 mm² vs. 0.93 mm²) were significantly larger for this group of patients than for those without graft disease. In the latter group more elongated smooth muscle cell nuclei (higher length/thickness ratio) were found in the tunica media of the saphenous vein segments. Thickening of the saphenous vein tunica media and chunky smooth muscle cell nuclei were identified as independent risk factors for graft disease development.

Conclusions

Saphenous vein tunica media hypertrophy (resulting in wall thickening) and chunky smooth muscle cell nuclei might predict the development of venous graft disease.     

Effect ofCalotropis latex on laticifers differentiation in callus cultures ofCalotropis procera

Laticifers differentiation in callus cultures of Calotropis procera (Asclepiadaceae) as affected by own latex and its fractions incorporated in Murashige and Skoog (MS) medium is described. Callus cultures have been maintained on MS medium with 2.3 ΜM 6-furfurylaminopurine (FAP) and 3.0 ΜM 1-naphthylacetic acid (NAA). Marked increase in laticifers differentiation (from 10.1 to 28.4 %) was observed on this medium supplemented with 1 % (v/v) of latex. Latex fractions containing proteins + complex polysaccharides or inorganic salts also increased laticifers differentiation (by 21.8 % and 24.1 %, respectively). Other fractions (free amino acid + saccharides, phenols and terpenes + sterols) had no marked effect on laticifers differentiation while alkaloid fraction inhibited it. Effect of latex on laticifers differentiation was much more profound than the reported optimal concentration of plant growth regulators (4.6 ΜM FAP + 1 ΜM IAA). This research was supported by grant-in-aid for research from the University Grants Commission (No. F3-65/91SR II), New Delhi, to Dr. KG. Ramawat.     

In vitro Hormonal Regulation of Laticifer Differentiation in Calotropis procera

Cultures of Calotropis procera were maintained on MS mediumsupplemented with 4·6 µM FAP and 3 µM NAA.Laticifer initials were observed in 2-week-old cultures whichwere converted into matured, branched, non-articulated laticifersin 4 weeks. It was observed that laticifer differentiation increasedwith the age of cultures, from 2·78% (in the second passage)to 15·11% (in the 12th passage). It has been establishedthat laticifer differentiation in vitro is a cytokinin-dependentprocess and among the cytokinins, FAP was more effective thanBA and 2-iP. But the type of auxin and its concentration alsoplay an important role in modifying the effect of cytokinin.Among the different auxins used IAA was more effective for laticiferdifferentiation than IBA and NAA, while 2,4D was inhibitory.Maximum laticifer differentiation (17·01% was observedon MS medium supplemented with 4·6 µM FAP and 1µM IAA.Copyright 1995, 1999 Academic Press Calotropis procera, callus culture, laticifer, differentiation, hormonal regulation     

Reactive oxygen species generation and mitochondrial dysfunction in the apoptotic cell death of human myeloid leukemia HL-60 cells by a dietary compound withaferin A with concomitant protection by <Emphasis Type="Italic">N</Emphasis>-acetyl cysteine

Induction of apoptosis in cancer cells has become the major focus of anti-cancer therapeutics development. WithaferinA, a major chemical constituent of Withania somnifera, reportedly shows cytotoxicity in a variety of tumor cell lines while its molecular mechanisms of action are not fully understood. We observed that withaferinA primarily induces oxidative stress in human leukemia HL-60 cells and in several other cancer cell lines. The withanolide induced early ROS generation and mitochondrial membrane potential (Δψ_mt) loss, which preceded release of cytochrome c, translocation of Bax to mitochondria and apoptosis inducing factor to cell nuclei. These events paralleled activation of caspases −9, −3 and PARP cleavage. WA also activated extrinsic pathway significantly as evidenced by time dependent increase in caspase-8 activity vis-à-vis TNFR-1 over expression. WA mediated decreased expression of Bid may be an important event for cross talk between intrinsic and extrinsic signaling. Furthermore, withaferinA inhibited DNA binding of NF-κB and caused nuclear cleavage of p65/Rel by activated caspase-3. N-acetyl-cysteine rescued all these events suggesting thereby a pro-oxidant effect of withaferinA. The results of our studies demonstrate that withaferinA induced early ROS generation and mitochondrial dysfunction in cancer cells trigger events responsible for mitochondrial -dependent and -independent apoptosis pathways.