Platinum resistant cancer cells conserve sensitivity to BH3 domains and obatoclax induced mitochondrial apoptosis

Resistance to cisplatin chemotherapy remains a major hurdle preventing effective treatment of many solid cancers. BAX and BAK are pivotal regulators of the mitochondrial apoptosis pathway, however little is known regarding their regulation in cisplatin resistant cells. Cisplatin induces DNA damage in both sensitive and resistant cells, however the latter exhibits a failure to initiate N-terminal exposure of mitochondrial BAK or mitochondrial SMAC release. Both phenotypes are highly sensitive to mitochondrial permeabilisation induced by exogenous BH3 domain peptides derived from BID, BIM, NOXA (which targets MCL-1 and A1), and there is no significant change in their prosurvival BCL2 protein expression profiles. Obatoclax, a small molecule inhibitor of pro-survival BCL-2 family proteins including MCL-1, decreases cell viability irrespective of platinum resistance status across a panel of cell lines selected for oxaliplatin resistance. In summary, selection for platinum resistance is associated with a block of mitochondrial death signalling upstream of BAX/BAK activation. Conservation of sensitivity to BH3 domain induced apoptosis can be exploited by agents such as obatoclax, which directly target the mitochondria and BCL-2 family.

Overcoming hydrolytic sensitivity and low solubility of phosphitylation reagents by combining ionic liquids with mechanochemistry

Ionic liquids have been used in combination with ball milling on a range of chlorophosphoramidite reagents to phosphitylate nucleosides and 2-deoxynucleosides. The enhanced stability offered by the ionic liquid mediated processes combined with efficient mass transfer induced by ball milling has enabled excellent yields to be obtained even when using small dialkyl amino groups as well as the more commonly used diisopropylamino protection.

Calbindin 2 (CALB2) Regulates 5-Fluorouracil Sensitivity in Colorectal Cancer by Modulating the Intrinsic Apoptotic Pathway

The role of the calcium binding protein, Calbindin 2 (CALB2), in regulating the response of colorectal cancer (CRC) cells to 5-Fluorouracil (5-FU) was investigated. Real-time RT-PCR and Western blot analysis revealed that CALB2 mRNA and protein expression were down-regulated in p53 wild-type and p53 null isogenic HCT116 CRC cell lines following 48 h and 72 h 5-FU treatment. Moreover, 5-FU-induced apoptosis was significantly reduced in HCT116 and LS174T CRC cell lines in which CALB2 expression had been silenced. Further investigation revealed that CALB2 translocated to the mitochondria following 5-FU treatment and that 5-FU-induced loss of mitochondrial membrane potential (Delta psi(m)) was abrogated in CALB2-silenced cells. Furthermore, CALB2 silencing decreased 5-FU-induced cytochrome c and smac release from the mitochondria and also decreased 5-FU-induced activation of caspases 9 and 3/7. Of note, co-silencing of XIAP overcame 5-FU resistance in CALB2-silenced cells. Collectively, these results suggest that following 5-FU treatment in CRC cell lines, CALB2 is involved in apoptosis induction through the intrinsic mitochondrial pathway. This indicates that CALB2 may be an important mediator of 5-FU-induced cell death. Moreover, down-regulation of CALB2 in response to 5-FU may represent an intrinsic mechanism of resistance to this anti-cancer drug.

BRCA1 - A good predictive marker of drug sensitivity in breast cancer treatment?

There are currently only two predictive markers of response to chemotherapy for breast cancer in routine clinical use, namely the Estrogen receptor-alpha and the HER2 receptor. The breast and ovarian cancer susceptibility gene BRCA1 is an important genetic factor in hereditary breast and ovarian cancer and there is increasing evidence of an important role for BRCA1 in the sporadic forms of both cancer types. Our group and numerous others have shown in both preclinical and clinical studies that BRCA1 is an important determinant of chemotherapy responses in breast cancer. In this review we will outline the current understanding of the role of BRCA1 as a determinant of response to DNA damaging and microtubule damaging chemotherapy. We will then discuss how the known functions of this multifaceted protein may provide mechanistic explanations for its role in chemotherapy responses. (c) 2006 Elsevier B.V. All rights reserved.

Motor skill deficits in children with partial hearing

AIM:
We examined the effect of partial hearing, including cochlear implantation, on the development of motor skills in children (aged 6-12y).

METHOD:
Three independent groups of children were selected: a partial hearing group (n=25 [14 males, 11 females]; mean age 8y 8mo, SD 1y 10mo), a nonverbal IQ-matched group (n=27 [15 males, 12 females]; mean age 9y, SD 1y 6mo), and an age-matched group (n=26 [8 males, 18 females]; mean age 8y 8mo, SD 1y 7mo) from three schools with special units for children with partial hearing. All children with partial hearing had a bilateral hearing loss >60 decibels. Motor and balance skills were assessed using the Movement Assessment Battery for Children (MABC) and two protocols from the NeuroCom Balance Master clinical procedures.

RESULTS:
The mean standardized total MABC score of the children with partial hearing (95% confidence interval [CI] 71.8-88.7) was significantly lower than both the age-matched (95% CI 95.8-111.4; p<0.01) and the IQ-matched (95% CI 87.6-103.0; p=0.03) comparison groups. The children with partial hearing had particular difficulties with balance, most notably during tests of intersensory demand. However, subgroup analyses revealed that the effect of cochlear implantation was clearly dependent on the nature of the task.

INTERPRETATION:
Children with partial hearing are at high risk of clinical levels of motor deficit, with balance difficulties providing support for conventional vestibular deficit theory. However, the effect of cochlear implantation suggests that other sensory systems may be involved. A broader ecological perspective, which takes into account factors external to the child, may prove a useful framework for future research.

Fasciola hepatica: Comparative effects of host resistance and parasite intra-specific interactions on size and reproductive histology in flukes from rats infected with isolates differing in triclabendazole sensitivity

The efficacies of putative fasciolicides and vaccines against Fasciola hepatica are frequently monitored in clinical and field trials by determination of fluke egg output in host faeces and by worm counts in the host liver at autopsy. Less often used are parameters based on fluke size and histology, yet these can provide important indications of specific effects on the development of particular germ-line or somatic tissues, especially in relation to the timing and profligacy of egg production. In this study. F. hepatica metacercariae of two distinct isolates, the triclabendazole (TCBZ)-sensitive Cullompton isolate and the TCBZ-resistant Oberon isolate, were administered to rats as single-isolate or mixed-isolate infections. At autopsy 16 weeks later individual adult flukes were counted, measured and the reproductive organs were examined histologically. The degree of development of the testis tubules in each fluke was represented by a numerical score, based on the proportion of the histological section profiles occupied by testis tissue. The level of anti-F. hepatica antibody in the serum of each rat was determined by ELISA. It was found that Cullompton flukes were significantly larger than Oberon flukes, and that significantly more Cullompton metacercariae developed to adults than Oberon metacercariae. The Cullompton flukes showed histological evidence of aspermy and spermatogenic arrest, which was reflected in quantitatively reduced testicular development, as compared with the Oberon isolate. In Cullompton flukes, parthenogenetic egg development is implied. The size of Cullompton and Oberon flukes was significantly related to the number of adult flukes recovered, to the number of metacercariae administered, and to the percentage success of infection. The testis development score in both isolates was significantly related to the number of adult flukes recovered but not to the number of metacercariae administered, or to the percentage success of infection. Fluke size was positively related to testis score for both isolates, and a significant negative relationship was found between percentage success of infection and metacercarial dose. The results are interpreted in terms of differing interactions between various numbers of young flukes and host immunity during invasion of and migration in the hepatic parenchyma, and of fluke intra-specific (possibly pheromonal) stimulatory effects in the final stages of development, within the host bile ducts. No significant relationships were found between host antibody levels and fluke size or testis score. False positive serological reactions were found in some rats that had been infected, but found to harbour no flukes at autopsy. Clearly the act of eliminating the flukes involved generation of an immune response. (C) 2011 Elsevier B.V. All rights reserved.