Dynamics in treatment response and disease progression of metastatic colorectal cancer (mCRC) patients with focus on BRAF status and primary tumor location: analysis of untreated RAS-wild-type mCRC patients receiving FOLFOXIRI either with or without panitumumab in the VOLFI trial (AIO KRK0109)

Purpose: In mCRC, disease dynamics may play a critical role in the understanding of long-term outcome. We evaluated depth of response (DpR), time to DpR, and post-DpR survival as relevant endpoints. Methods: We analyzed DpR by central review of computer tomography images (change from baseline to smallest tumor diameter), early tumor shrinkage (≥ 20% reduction in tumor diameter at first reassessment), time to DpR (study randomization to DpR-image), post-DpR progression-free survival (pPFS = DpR-image to tumor progression or death), and post-DpR overall survival (pOS = DpR-image to death) with special focus on BRAF status in 66 patients and primary tumor site in 86 patients treated within the VOLFI-trial, respectively. Results: BRAF wild-type (BRAF-WT) compared to BRAF mutant (BRAF-MT) patients had greater DpR (− 57.6% vs. − 40.8%, p = 0.013) with a comparable time to DpR [4.0 (95% CI 3.1–4.4) vs. 3.9 (95% CI 2.5–5.5) months; p = 0.8852]. pPFS was 6.5 (95% CI 4.9–8.0) versus 2.6 (95% CI 1.2–4.0) months in favor of BRAF-WT patients (HR 0.24 (95% CI 0.11–0.53); p < 0.001). This transferred into a significant difference in pOS [33.6 (95% CI 26.0–41.3) vs. 5.4 (95% CI 5.0–5.9) months; HR 0.27 (95% CI 0.13–0.55); p < 0.001]. Similar observations were made for patients stratified for primary tumor site. Conclusions: BRAF-MT patients derive a less profound treatment response compared to BRAF-WT patients. The difference in outcome according to BRAF status is evident after achievement of DpR with BRAF-MT patients hardly deriving any further disease control beyond DpR. Our observations hint towards an aggressive tumor evolution in BRAF-MT tumors, which may already be molecularly detectable at the time of DpR

Comparison of Functional Proteomic Analyses of Human Breast Cancer Cell Lines T47D and MCF7

T47D and MCF7 are two human hormone-dependent breast cancer cell lines which are widely used as experimental models for in vitro and in vivo (tumor xenografts) breast cancer studies. Several proteins involved in cancer development were identified in these cell lines by proteomic analyses. Although these studies reported the proteomic profiles of each cell line, until now, their differential protein expression profiles have not been established. Here, we used two-dimensional gel and mass spectrometry analyses to compare the proteomic profiles of the two cell lines, T47D and MCF7. Our data revealed that more than 164 proteins are differentially expressed between them. According to their biological functions, the results showed that proteins involved in cell growth stimulation, anti-apoptosis mechanisms and cancerogenesis are more strongly expressed in T47D than in MCF7. These proteins include G1/S-specific cyclin-D3 and prohibitin. Proteins implicated in transcription repression and apoptosis regulation, including transcriptional repressor NF-X1, nitrilase homolog 2 and interleukin-10, are, on the contrary, more strongly expressed in MCF7 as compared to T47D. Five proteins that were previously described as breast cancer biomarkers, namely cathepsin D, cathepsin B, protein S100-A14, heat shock protein beta-1 (HSP27) and proliferating cell nuclear antigen (PCNA), are found to be differentially expressed in the two cell lines. A list of differentially expressed proteins between T47D and MCF7 was generated, providing useful information for further studies of breast cancer mechanisms with these cell lines as models

Involvement of KSRP in the post-transcriptional regulation of human iNOS expression–complex interplay of KSRP with TTP and HuR

We purified the KH-type splicing regulatory protein (KSRP) as a protein interacting with the 3′-untranslated region (3′-UTR) of the human inducible nitric oxide (iNOS) mRNA. Immunodepletion of KSRP enhanced iNOS 3′-UTR RNA stability in in vitro-degradation assays. In DLD-1 cells overexpressing KSRP cytokine-induced iNOS expression was markedly reduced. In accordance, downregulation of KSRP expression increases iNOS expression by stabilizing iNOS mRNA. Co-immunoprecipitations showed interaction of KSRP with the exosome and tristetraprolin (TTP). To analyze the role of KSRP binding to the 3′-UTR we studied iNOS expression in DLD-1 cells overexpressing a non-binding mutant of KSRP. In these cells, iNOS expression was increased. Mapping of the binding site revealed KSRP interacting with the most 3′-located AU-rich element (ARE) of the human iNOS mRNA. This sequence is also the target for HuR, an iNOS mRNA stabilizing protein. We were able to demonstrate that KSRP and HuR compete for this binding site, and that intracellular binding to the iNOS mRNA was reduced for KSRP and enhanced for HuR after cytokine treatment. Finally, a complex interplay of KSRP with TTP and HuR seems to be essential for iNOS mRNA stabilization after cytokine stimulation

Simple model systems: a challenge for Alzheimer's disease

The success of biomedical researches has led to improvement in human health and increased life expectancy. An unexpected consequence has been an increase of age-related diseases and, in particular, neurodegenerative diseases. These disorders are generally late onset and exhibit complex pathologies including memory loss, cognitive defects, movement disorders and death. Here, it is described as the use of simple animal models such as worms, fishes, flies, Ascidians and sea urchins, have facilitated the understanding of several biochemical mechanisms underlying Alzheimer's disease (AD), one of the most diffuse neurodegenerative pathologies. The discovery of specific genes and proteins associated with AD, and the development of new technologies for the production of transgenic animals, has helped researchers to overcome the lack of natural models. Moreover, simple model systems of AD have been utilized to obtain key information for evaluating potential therapeutic interventions and for testing efficacy of putative neuroprotective compounds

RETRACTED ARTICLE: Age-dependent Increase in Desmosterol Restores DRM Formation and Membrane-related Functions in Cholesterol-free DHCR24−/− Mice

Cholesterol is a prominent modulator of the integrity and functional activity of physiological membranes and the most abundant sterol in the mammalian brain. DHCR24-knock-out mice lack cholesterol and accumulate desmosterol with age. Here we demonstrate that brain cholesterol deficiency in 3-week-old DHCR24−/− mice was associated with altered membrane composition including disrupted detergent-resistant membrane domain (DRM) structure. Furthermore, membrane-related functions differed extensively in the brains of these mice, resulting in lower plasmin activity, decreased β-secretase activity and diminished Aβ generation. Age-dependent accumulation and integration of desmosterol in brain membranes of 16-week-old DHCR24−/− mice led to the formation of desmosterol-containing DRMs and rescued the observed membrane-related functional deficits. Our data provide evidence that an alternate sterol, desmosterol, can facilitate processes that are normally cholesterol-dependent including formation of DRMs from mouse brain extracts, membrane receptor ligand binding and activation, and regulation of membrane protein proteolytic activity. These data indicate that desmosterol can replace cholesterol in membrane-related functions in the DHCR24−/− mouse

Aβ42 Mutants with Different Aggregation Profiles Induce Distinct Pathologies in Drosophila

Aggregation of the amyloid-β-42 (Aβ42) peptide in the brain parenchyma is a pathological hallmark of Alzheimer's disease (AD), and the prevention of Aβ aggregation has been proposed as a therapeutic intervention in AD. However, recent reports indicate that Aβ can form several different prefibrillar and fibrillar aggregates and that each aggregate may confer different pathogenic effects, suggesting that manipulation of Aβ42 aggregation may not only quantitatively but also qualitatively modify brain pathology. Here, we compare the pathogenicity of human Aβ42 mutants with differing tendencies to aggregate. We examined the aggregation-prone, EOFAD-related Arctic mutation (Aβ42Arc) and an artificial mutation (Aβ42art) that is known to suppress aggregation and toxicity of Aβ42 in vitro. In the Drosophila brain, Aβ42Arc formed more oligomers and deposits than did wild type Aβ42, while Aβ42art formed fewer oligomers and deposits. The severity of locomotor dysfunction and premature death positively correlated with the aggregation tendencies of Aβ peptides. Surprisingly, however, Aβ42art caused earlier onset of memory defects than Aβ42. More remarkably, each Aβ induced qualitatively different pathologies. Aβ42Arc caused greater neuron loss than did Aβ42, while Aβ42art flies showed the strongest neurite degeneration. This pattern of degeneration coincides with the distribution of Thioflavin S-stained Aβ aggregates: Aβ42Arc formed large deposits in the cell body, Aβ42art accumulated preferentially in the neurites, while Aβ42 accumulated in both locations. Our results demonstrate that manipulation of the aggregation propensity of Aβ42 does not simply change the level of toxicity, but can also result in qualitative shifts in the pathology induced in vivo

A Functional Misexpression Screen Uncovers a Role for Enabled in Progressive Neurodegeneration

Drosophila is a well-established model to study the molecular basis of neurodegenerative diseases. We carried out a misexpression screen to identify genes involved in neurodegeneration examining locomotor behavior in young and aged flies. We hypothesized that a progressive loss of rhythmic activity could reveal novel genes involved in neurodegenerative mechanisms. One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain. Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant. Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor. Thus, this mutant recapitulates two important features of human neurodegenerative diseases, i.e., vulnerability of certain neuronal populations and progressive degeneration, offering a unique scenario in which to unravel the specific mechanisms in an easily tractable organism

The Toll→NFκB Signaling Pathway Mediates the Neuropathological Effects of the Human Alzheimer's Aβ42 Polypeptide in Drosophila

Alzheimer's (AD) is a progressive neurodegenerative disease that afflicts a significant fraction of older individuals. Although a proteolytic product of the Amyloid precursor protein, the Αβ42 polypeptide, has been directly implicated in the disease, the genes and biological pathways that are deployed during the process of Αβ42 induced neurodegeneration are not well understood and remain controversial. To identify genes and pathways that mediated Αβ42 induced neurodegeneration we took advantage of a Drosophila model for AD disease in which ectopically expressed human Αβ42 polypeptide induces cell death and tissue degeneration in the compound eye. One of the genes identified in our genetic screen is Toll (Tl). It encodes the receptor for the highly conserved Tl→NFkB innate immunity/inflammatory pathway and is a fly homolog of the mammalian Interleukin-1 (Ilk-1) receptor. We found that Tl loss-of-function mutations dominantly suppress the neuropathological effects of the Αβ42 polypeptide while gain-of-function mutations that increase receptor activity dominantly enhance them. Furthermore, we present evidence demonstrating that Tl and key downstream components of the innate immunity/inflammatory pathway play a central role in mediating the neuropathological activities of Αβ42. We show that the deleterious effects of Αβ42 can be suppressed by genetic manipulations of the Tl→NFkB pathway that downregulate signal transduction. Conversely, manipulations that upregulate signal transduction exacerbate the deleterious effects of Aβ42. Since postmortem studies have shown that the Ilk-1→NFkB innate immunity pathway is substantially upregulated in the brains of AD patients, the demonstration that the Tl→NFkB signaling actively promotes the process of Αβ42 induced cell death and tissue degeneration in flies points to possible therapeutic targets and strategies