Ferulic acid enhances the radiation sensitivity of lung and liver carcinoma cells by collapsing redox homeostasis: mechanistic involvement of Akt/p38 MAPK signalling pathway

Abstract

The major drawback of anticancer therapy is the development of resistance against drugs and radiation at the later phase of treatment which may lead to recurrences of the disease. Therefore, strategy was taken to enhance radiation sensitivity of lung (A549) and liver (HepG2) carcinoma cells by treatment with ferulic acid (FA) prior to irradiation. FA pre-treatment initially decreased reactive oxygen species (ROS) level in carcinoma cells which induced reductive stress and cytostasis. To overcome this stress, cellular mechanism increased the Keap1 level to down-regulate nuclear localisation of Nrf2 and its dependent antioxidant system. The antioxidant system reached the lowest level after 3 and 6?h of FA treatment in A549 and HepG2 cells respectively. As endogenous ROS were still being generated at same rate, ROS level was clearly higher than control which changed the reductive stress to oxidative stress. Exposure to γ-radiation in this condition further increased ROS level and caused radio-sensitisation of carcinoma cells. Combination of irradiation (IR) and FA activated mitochondrial apoptotic pathway and concomitantly inhibited the cell cycle progression and survival pathway over the IR group. Moreover, the combination treatment showed significant tumour regression, caspase 3 activation and nuclear fragmentation in tumour tissue compared to radiation alone. In contrast, FA pre-treatment protected peripheral blood mononuclear cells (PBMC) and normal lung fibroblast WI38 cells from radiation damage. Together, combination treatment offers effective strategy of killing cancer cells and demonstrates its potential for increasing the efficacy of radio-therapy.     

p38δ Regulates p53 to Control p21Cip1 Expression in Human Epidermal Keratinocytes

PKCδ suppresses keratinocyte proliferation via a mechanism that involves increased expression of p21^Cip1. However, the signaling mechanism that mediates this regulation is not well understood. Our present studies suggest that PKCδ activates p38δ leading to increased p21^Cip1 promoter activity and p21^Cip1 mRNA/protein expression. We further show that exogenously expressed p38δ increases p21^Cip1 mRNA and protein and that p38δ knockdown or expression of dominant-negative p38 attenuates this increase. Moreover, p53 is an intermediary in this regulation, as p38δ expression increases p53 mRNA, protein, and promoter activity, and p53 knockdown attenuates the activation. We demonstrate a direct interaction of p38δ with PKCδ and MEK3 and show that exogenous agents that suppress keratinocyte proliferation activate this pathway. We confirm the importance of this regulation using a stratified epidermal equivalent model, which mimics in vivo-like keratinocyte differentiation. In this model, PKCδ or p38δ knockdown results in reduced p53 and p21^Cip1 levels and enhanced cell proliferation. We propose that PKCδ activates a MEKK1/MEK3/p38δ MAPK cascade to increase p53 levels and p53 drives p21^Cip1 gene expression.     

A bacteriological profile of bottled water sold in Bangladesh

Four different brands of bottled water had counts of aerobic bacteria ranging from 10³ to 10⁶ colony forming units/100 ml. Pathogens isolated includedPseudomonas (in all brands),Alcaligenes andEscherichia coli (each in three brands), andKlebsiella, Enterobacter andShigella (each in two brands). All four brands were judged to be unsatisfactory by accepted health standards.     

Effect of Carbon Source on Production of α-L-Arabinofuranosidase by Aureobasidium pullulans

A color-variant strain of Aureobasidium pullulans (NRRL Y-12974) produced α-L-arabinofuranosidase (α-L-AFase) when grown in liquid culture on sugar beet arabinan, wheat arabinoxylan, L-arabinose, L-arabitol, xylose, xylitol, oat spelt xylan, corn fiber, or arabinogalactan. L-Arabinose was most effective for production of both whole-broth and extracellular α-L-AFase activity, followed by L-arabitol. Oat spelt xylan, sugar beet arabinan, xylose, xylitol, and wheat arabinoxylan were intermediate in their ability to support α-L-AFase production. Lower amounts of enzyme activity were detected in corn fiber- and arabinogalactan-grown cultures. Received: 16 April 1998 / Accepted: 17 June 1998     

Recruitment of multiple alleles within the Eb recombinational hotspot in murine MHC

Genetic recombination has been proposed to have played a major role in generating the extensive polymorphism that distinguishes the genes of the major histocompatibility complex (MHC). The proximal region of the murine H-2 represents a unique segment of DNA encompassing at least four hotspots for meiotic recombination. One of these hotspots lies within the second intron of the class II Eb gene and has been defined at the nucleotide level for a number of simple two-allele crosses. In this report we studied two crosses in which one or both parents in themselves were H2Eb recombinants and three alleles were present within the hotspots of each pair of the parental haplotypes. Nucleotide analysis indicated that the break points in these secondary recombinants, like those in the primary recombinants, were also discrete and clustered within the H2Eb second intron. Thus, in one instance two and in the other instance three alleles were present within the hotspots of these recombinants. These observations strongly suggest that meiotic recombination could be an important mechanism contributing to MHC polymorphism.     

Carbon storage in relation to soil size-fractions under tropical tree-based land-use systems

The extent of carbon (C) sequestration in soils under agroforestry systems in relation to soil types (fraction sizes) and vegetation structure remains largely unexplored. This study examined soil C storage, an indicator of C sequestration potential, in homegardens (HGs), natural forest, and single-species stands of coconut (Cocos nucifera), rice (Oryza sativa)-paddy, and rubber (Hevea brasiliensis), in Thrissur district, Kerala, India. Soil samples collected from four depth zones up to 1 m were fractionated to three size classes (250 – 2000 µm, 53 – 250 µm, ?<?53 µm) and their total C content determined. Total C stock (Mg ha^?1) was highest in forests (176.6), followed by managed tree-based systems, and lowest in rice-paddy field (55.6). The results show storage of higher amounts of C in the ?<?53 µm fraction, the most stable form of C in soil, up to one- meter depth, in land-use systems with high stand density of trees such as forests and small-sized HG. Although the results do not allow comparison of changes in soil C stock in different land-use systems, they show higher C storage in soils under tree-based land-use systems compared with the treeless (rice-paddy) system, especially in lower soil depths, suggesting the higher soil C sequestration potential of tree-based systems, and thereby their role in reducing atmospheric concentration of carbon dioxide.     

Purification and Characterization of a Sperm Motility Inhibiting Factor from Caprine Epididymal Plasma

Several studies have been reported on the occurrence of sperm motility inhibiting factors in the male reproductive fluids of different mammalian species, but these proteins have not been adequately purified and characterized. A novel sperm motility inhibiting factor (MIF-II) has been purified from caprine epididymal plasma (EP) by Hydroxylapatite gel adsorption chromatography, DEAE-Cellulose ion-exchange chromatography and chromatofocusing. The MIF-II has been purified to apparent homogeneity and the molecular weight estimated by Sephacryl S-300 gel filtration is 160 kDa. MIF-II is a dimeric protein, made up of two subunits each having a molecular mass of 80 kDa as shown by SDS-PAGE. The isoelectric point of MIF-II is 5.1 as determined by chromatofocusing and isoelectric focusing. It is a heat labile protein and maximal active at the pH 6.9 to 7.5. The sperm motility inhibiting protein factor at 2 µg/ml (12.5 nM) level showed maximal motility-inhibiting activity. The observation that the epididymal plasma factor lowered the intracellular cAMP level of spermatozoa in a concentration-dependent manner suggests that it may block the motility of caprine cauda spermatozoa by interfering the cAMP dependent motility function. The results revealed that the purified protein factor has the potential of sperm motility inhibition and may serve as a vaginal contraceptive. The antibody raised against the MIF-II has the potential for enhancement of forward motility of cauda-spermatozoa. This antibody may thus be useful for solving some of the problems of male infertility due to low sperm motility.     

Comparative study of the chondrogenic potential of human bone marrow stromal cells, neonatal chondrocytes and adult chondrocytes

Cartilage tissue engineering is still a major clinical challenge with optimisation of a suitable source of cells for cartilage repair/regeneration not yet fully addressed. The aims of this study were to compare and contrast the differences in chondrogenic behaviour between human bone marrow stromal cells (HBMSCs), human neonatal and adult chondrocytes to further our understanding of chondroinduction relative to cell maturity and to identify factors that promote chondrogenesis and maintain functional homoeostasis. Cells were cultured in monolayer in either chondrogenic or basal medium, recapitulating procedures used in existing clinical procedures for cell-based therapies. Cell doubling time, morphology and alkaline phosphatase specific activity (ALPSA) were determined at different time points. Expression of chondrogenic markers (SOX9, ACAN and COL2A1) was compared via real time polymerase chain reaction. Amongst the three cell types studied, HBMSCs had the highest ALPSA in basal culture and lowest ALPSA in chondrogenic media. Neonatal chondrocytes were the most proliferative and adult chondrocytes had the lowest ALPSA in basal media. Gene expression analysis revealed a difference in the temporal expression of chondrogenic markers which were up regulated in chondrogenic medium compared to levels in basal medium. Of the three cell types studied, adult chondrocytes offer a more promising cell source for cartilage tissue engineering. This comparative study revealed differences between the microenvironment of all three cell types and provides useful information to inform cell-based therapies for cartilage regeneration.