Expression Of Microtubule-associated Protein Tau Research Articles

The relationships between the chemosensitivity of human gastric cancer to paclitaxel and the expressions of class III β-tubulin, MAPT, and survivin.

Lack of effective biomarkers is one of the challenges in current chemotherapy to predict drug response and sensitivity. This study was carried out to investigate the relationships between the expressions of class III β-tubulin, microtubule-associated protein tau (MAPT), survivin, and the sensitivity of primary gastric cancer (GC) to paclitaxel treatment. Reverse transcription PCR and Western blot were used to evaluate the mRNA and protein expressions of class III β-tubulin, MAPT, and survivin in fifty-four GC tissues. Viable tumor cells from gastric carcinomas were tested for their sensitivity to paclitaxel using adenosine triphosphate-based tumor chemosensitivity assay in vitro. Out of 54 samples, 30 samples were sensitive to paclitaxel, while the other 24 samples were resistant. The overall efficacy of paclitaxel was 55.56% (30/54). The mRNA expressions of class III β-tubulin and survivin were significantly correlated with the histological grade (P = 0.029, 0.009, respectively). The sensitivity of GC patients to paclitaxel treatment was inversely correlated with the mRNA and protein expressions of class III β-tubulin (P < 0.01), MAPT (P < 0.05), and survivin (P < 0.05). A significant positive correlation was found between class III β-tubulin and MAPT expression at mRNA and protein levels (mRNA: P = 0.037; protein: P = 0.001). Our results indicate that the expression levels of class III β-tubulin, MAPT, and survivin are good biomarkers for predicting the sensitivity of GC to paclitaxel treatment.

DNA methylation of the MAPT gene in Parkinson's disease cohorts and modulation by vitamin E In Vitro

Parkinson's disease (PD) is a neurodegenerative disorder for which environmental factors influence disease risk and may act via an epigenetic mechanism. The microtubule-associated protein tau (MAPT) is a susceptibility gene for idiopathic PD. Methylation levels were determined by pyrosequencing of bisulfite-treated DNA in a leukocyte cohort (358 PD patients and 1084 controls) and in two brain cohorts (Brain1, comprising 69 cerebellum controls; and Brain2, comprising 3 brain regions from 28 PD patients and 12 controls). In vitro assays involved the transfection of methylated promoter-luciferase constructs or treatment with an exogenous micronutrient. In normal leukocytes, the MAPT H1/H2 diplotype and sex were predictors of MAPT methylation. Haplotype-specific pyrosequencing confirmed that the H1 haplotype had higher methylation than the H2 haplotype in normal leukocytes and brain tissues. MAPT methylation was negatively associated with MAPT expression in the Brain1 cohort and in transfected cells. Methylation levels differed between three normal brain regions (Brain2 cohort, putamen < cerebellum < anterior cingulate cortex). In PD samples, age at onset was positively associated with MAPT methylation in leukocytes. Moreover, there was hypermethylation in the cerebellum and hypomethylation in the putamen of PD patients compared with controls (Brain2 cohort). Finally, leukocyte methylation status was positively associated with blood vitamin E levels, and the effect was more significant in H2 haplotype carriers; this result was confirmed in cells that were exposed to 100 μM vitamin E. The significant effects of sex, diplotype, and brain region suggest that hypermethylation of the MAPT gene is neuroprotective by reducing MAPT expression. The effect of vitamin E on MAPT represents a possible gene-environment interaction.

Altered CpG methylation in sporadic Alzheimer's disease is associated with APP and MAPT dysregulation

The hallmark of Alzheimer's disease (AD) pathology is an accumulation of amyloid β (Aβ) and phosphorylated tau, which are encoded by the amyloid precursor protein (APP) and microtubule-associated protein tau (MAPT) genes, respectively. Less than 5% of all AD cases are familial in nature, i.e. caused by mutations in APP, PSEN1 or PSEN2. Almost all mutations found in them are related to an overproduction of Aβ1-42, which is prone to aggregation. While these genes are mutation free, their function, or those of related genes, could be compromised in sporadic AD as well. In this study, pyrosequencing analysis of post-mortem brains revealed aberrant CpG methylation in APP, MAPT and GSK3B genes of the AD brain. These changes were further evaluated by a newly developed in vitro-specific DNA methylation system, which in turn highlighted an enhanced expression of APP and MAPT. Cell nucleus sorting of post-mortem brains revealed that the methylation changes of APP and MAPT occurred in both neuronal and non-neuronal cells, whereas GSK3B was abnormally methylated in non-neuronal cells. Further analysis revealed an association between abnormal APP CpG methylation and apolipoprotein E ε4 allele (APOE ε4)-negative cases. The presence of a small number of highly methylated neurons among normal neurons contribute to the methylation difference in APP and MAPT CpGs, thus abnormally methylated cells could compromise the neural circuit and/or serve as 'seed cells' for abnormal protein propagation. Our results provide a link between familial AD genes and sporadic neuropathology, thus emphasizing an epigenetic pathomechanism for sporadic AD.

Regulation of microtubule-associated protein tau (MAPT) by miR-34c-5p determines the chemosensitivity of gastric cancer to paclitaxel

Human miR-34c has been reported to be associated with various human malignancies; however, it remains unknown whether miR-34c is involved in chemoresistance in gastric cancer. The aim of this study was to investigate the role of miR-34c in gastric cancer. The adenosine triphosphate-based tumor chemosensitivity assay was used to measure drug sensitivity in gastric cancer samples. The expression levels of miRNA were determined by reverse transcriptase polymerase chain reaction (PCR) and those of protein were by Western blot analysis. Luciferase activity assay was used to verify the target genes of miRNAs. MTT assay was used to test the drug-resistant phenotype changes in cancer cells via overregulation of miRNAs. The methylation status of neighboring CpG islands of miR-34c-5p was analyzed by Bisulfite Sequencing PCR and methylation-specific PCR. Quantitative real-time polymerase chain reaction demonstrated that expression of miR-34c-5p was downregulated in paclitaxel-resistant gastric cancer samples (p < 0.01). Cells derived from gastric cancer tissues with low miR-34c-5p expression and high microtubule-associated protein tau (MAPT) protein expression tended to have increased chemoresistance to paclitaxel in vitro. Luciferase activity assay confirmed that the 3'-UTR of MAPT mRNA contains a functional miR-34c-5p binding site. Overexpression of miR-34c-5p significantly downregulated MAPT protein expression and increased the chemosensitivity of paclitaxel-resistant gastric cancer cells. Further investigation demonstrated that differential methylation of CpG islands neighboring the miR-34c promoter regulated the expression of miR-34c-5p in gastric cancer cell lines. DNA methylation, dysregulation of miR-34c-5p, and MAPT expression are critical factors in the chemoresistance of gastric cancer to paclitaxel.

The MAPT locus—a genetic paradigm in disease susceptibility

Understanding how genetic variation can confer susceptibility to neurological disease is an urgent priority. A new gene-expression study has explored the relationship between DNA sequence variation at the microtubule-associated protein tau (MAPT) locus and MAPT expression in the brain, providing an exciting new paradigm for the field.

MAPT expression and splicing is differentially regulated by brain region: relation to genotype and implication for tauopathies

The MAPT (microtubule-associated protein tau) locus is one of the most remarkable in neurogenetics due not only to its involvement in multiple neurodegenerative disorders, including progressive supranuclear palsy, corticobasal degeneration, Parksinson's disease and possibly Alzheimer's disease, but also due its genetic evolution and complex alternative splicing features which are, to some extent, linked and so all the more intriguing. Therefore, obtaining robust information regarding the expression, splicing and genetic regulation of this gene within the human brain is of immense importance. In this study, we used 2011 brain samples originating from 439 individuals to provide the most reliable and coherent information on the regional expression, splicing and regulation of MAPT available to date. We found significant regional variation in mRNA expression and splicing of MAPT within the human brain. Furthermore, at the gene level, the regional distribution of mRNA expression and total tau protein expression levels were largely in agreement, appearing to be highly correlated. Finally and most importantly, we show that while the reported H1/H2 association with gene level expression is likely to be due to a technical artefact, this polymorphism is associated with the expression of exon 3-containing isoforms in human brain. These findings would suggest that contrary to the prevailing view, genetic risk factors for neurodegenerative diseases at the MAPT locus are likely to operate by changing mRNA splicing in different brain regions, as opposed to the overall expression of the MAPT gene.

Topoisomerase II alpha gene status, HER2, and microtubule-associated protein tau as predictors of pathologic complete response after neoadjuvant chemotherapy.

10555 Background: There is growing evidence that topoisomerase II-alpha (TOPOIIα) is a marker for anthracycline-, and microtubule-associated protein tau (MAPT) for taxane sensitivity. HER2 has been described as a marker of both anthracycline and taxane sensitivity.The goal of our study was to examine the predictive and prognostic value of TOPOIIα, MAPT and HER2 expression in breast cancer patients (pts) who received neoadjuvant chemotherapy (NAC) based on anthracycline-taxane regimens. We analyzed the relationship between these biomarkers and pathological complete response (pCR), disease-free survival (DFS) and overall survival (OS). Methods: Between November 1993-2009, 140 pts (mean age 52 years) with locally advanced breast cancer (T1-4, N0-3, M0) were retrospectively studied. The study contained 2 groups: group A included 85 pts who received NAC with an anthracycline-taxane regimen and group B included the last 55 pts who received NAC with only an anthracycline-based regimen. HER2 was tested by immunohistochemistry (IH) or FISH, TOPOIIα by CISH and MAPT by IH. Expression of these proteins was evaluated in core needle breast biopsy. Results: Overall, 12 pts (8.5%) had a pCR. TOPOIIα was amplified in 6 (4%) of the tumors. Among pts without amplification, 6 (4%) had deletion of the TOPOIIα, and 10 (7%) polysomia of chromosome 17. TOPOIIα gene aberrations (amplification, deletion, polysomia), which was present in 22 (25%) of the tumors, was a strong predictive factor for pCR (p=0.018) but showed no direct association with prognostic outcome in multivariate analysis. HER2 amplification, which was present in 16% (21) of the tumors, show no direct association with pCR, DFS or OS. Finally, differences by treatment arm or pCR in low versus high MAPT expression groups were not observed, indicating that MAPT is not a useful predictive marker for taxane-based chemotherapy. In multivariate analysis high MAPT expression was associated with longer DFS (p=0.002). Conclusions: TOPOIIα gene aberrations but not HER2 are highly predictive of pCR for anthracycline-based regimen. MAPT is not associated with response to taxanes but has a prognostic value.

Abstract P4-01-01: Combination Treatment with Fulvestrant and Various Cytotoxic Agents Has a Synergistic Effect in ER-Positive Breast Cancer Cell Lines In Vitro and In Vivo.

Abstract Background: Patients with estrogen receptor (ER)-positive breast cancers have a better prognosis than those with ER-negative breast cancers since they can be treated with anti-estrogen therapies. However, ER-positive breast cancers have low sensitivity to chemotherapy and the survival benefitof chemotherapy is limited. Microtubule associated protein-tau (MAPT) plays an important role in taxane sensitivity. In a previous study we showed that ER signaling influenced MAPT expression and that fulvestrant, an estrogen receptor antagonist, downregulated MAPT and reversed resistance to taxane in MAPT-and ER-positive breast cancer cells (SABCS 2009, Abstract 2118). In clinical treatment for breast cancer, the advantages and disadvantages of combination treatment with endocrine therapy and chemotherapy have long been discussed. Several studies have shown that endocrine therapy has an antagonistic effect on chemotherapy, which suggests that concurrent use of a hormone drug and a chemotherapeutic agent should be avoided clinically. However, most of these studies used tamoxifen (TAM) and anthracycline regimens. The effects of combination treatment using new hormone therapies, such as aromatase inhibitors or fulvestrant, and chemotherapeutic agents have not been examined thoroughly. In this study we evaluated the effects of combinations of hormone drugs and chemotherapeutic agents in vitro and in vivo. Methods: In vitro, the effects of different combinations of five chemotherapeutic agents (doxorubicin, paclitaxel, docetaxel, vinorelbine, and 5-FU) and three hormone drugs (TAM, 4-hydroxytamoxifen (4OH-TAM), and fulvestrant) were examined in ER-positive breast cancer cell lines (MCF-7, ZR75-1) using CalcuSyn software. The cells were also exposed to hormone drugs and changes in chemoresistant factors such as Bcl2, multidrug resistance-associated protein 1 (MRP1), and MAPT were examined. In vivo, xenografts were created using MCF-7 cells transplanted into BALB/c nu/nu mice. Tumor sizes were evaluated after the mice were treated with tamoxifen alone, fulvestrant alone, docetaxel alone, and combinations of these drugs. Results: Combination treatment with fulvestrant and all chemotherapeutic agents in vitro showed a synergistic effect regardless of the fulvestrant dose. In contrast, TAM showed an antagonistic effect with all the chemotherapeutic agents, with the strongest antagonism occurring at a low dose of TAM. 4OH-TAM showed an antagonistic effect with doxorubicin and 5-FU, and a synergistic effect with taxanes and vinorelbine. In the analysis of chemoresistant factors, Bcl2 and MAPT were downregulated by fulvestrant, but upregulated by TAM and 4OH-TAM. In vivo, the combination of fulvestrant and docetaxel showed the strongest inhibitory effect on tumor growth. Conclusion: TAM and 4OH-TAM had different effects in combination with chemotherapeutic agents. Fulvestrant downregulated ER and chemoresistant factors such as Bcl2 and MAPT, which are regulated via ER. Fulvestrant showed good compatibility with all the evaluated chemotherapeutic agents in vitro and in vivo. These results suggest that combination therapy with fulvestrant and chemotherapeutic agents may be effective for ER-positive breast cancers. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P4-01-01.

The estrogen receptor influences microtubule-associated protein tau (MAPT) expression and the selective estrogen receptor inhibitor fulvestrant downregulates MAPT and increases the sensitivity to taxane in breast cancer cells

IntroductionMicrotubule-associated protein tau (MAPT) inhibits the function of taxanes and high expression of MAPT decreases the sensitivity to taxanes. The relationship between estrogen receptor (ER) and MAPT in breast cancer is unclear. In this study, we examined the correlation of MAPT expression with the sensitivity of human breast cancer cells to taxanes, and the relationship between ER and MAPT.MethodsThe correlation between MAPT expression and sensitivity to taxanes was investigated in 12 human breast cancer cell lines. Alterations in cellular sensitivity to taxanes were evaluated after knockdown of MAPT expression. ER expression was knocked down or stimulated in MAPT- and ER-positive cell lines to examine the relationship between ER and MAPT. The cells were also treated with hormone drugs (tamoxifen and fulvestrant) and taxanes.ResultsmRNA expression of MAPT did not correlate with sensitivity to taxanes. However, expression of MAPT protein isoforms of less than 70 kDa was correlated with a low sensitivity to taxanes. Downregulation of MAPT increased cellular sensitivity to taxanes. MAPT protein expression was increased by stimulation with 17-β-estradiol or tamoxifen, but decreased by ER downregulation and by fulvestrant, an ER inhibitor. The combination of fulvestrant with taxanes had a synergistic effect, whereas tamoxifen and taxanes had an antagonistic effect.ConclusionsExpression of MAPT protein isoforms of less than 70 kDa is correlated with a low sensitivity to taxanes in breast cancer cells. ER influences MAPT expression and fulvestrant increases the sensitivity to taxanes in MAPT- and ER-positive breast cancer cells.

Microtubule Associated Protein-Tau (MAPT) Is Influenced by ER: ICI182,780, a Selective ER Inhibitor, Down-Regulates MAPT Expression and Reverses Resistance to Taxanes in MAPT- and ER-Positive Breast Cancer Cells.

Abstract Background: Taxanes are important drugs in treatment of breast cancer. These drugs bind to tubulin and suppress spindle microtubule dynamics, which leads to cell cycle arrest in the G2/M phase followed by apoptosis. However, resistance to taxane therapy prevents some patients from benefiting from these drugs. Several mechanisms of taxane resistance have been described, including the involvement of microtubule-associated protein-tau (MAPT). MAPT binds to the same pocket as taxanes in microtubules and obstructs the function of the drug. Estrogen receptors (ER) are transcriptional factors that play an important role in the development and progression of breast cancer. However, the relationship between ER and MAPT in breast cancer is not entirely clear. In this study we examined the correlation between MAPT expression and the sensitivity of human breast cancer cells to taxanes, and the relationship between ER and MAPT at the protein level in these cells. We also examined combination therapy with hormone drugs and taxanes.Methods: The correlation between MAPT expression and sensitivity to taxanes was examined in 12 human breast cancer cell lines using real time PCR, western blotting analysis and an MTS assay. Following small interfering RNA (siRNA) knockdown of MAPT expression, the alteration of cellular sensitivity to taxanes was examined by MTS assay, flow cytometry and immunofluorescence. To examine the relationship between ER and MAPT, ER expression was knocked down with siRNA or stimulated with 17-β-estradiol in MAPT- and ER-positive cell lines (MCF-7 and ZR75.1, respectively). The cells were also treated with hormone drugs (tamoxifen and ICI182,780) and changes in MAPT protein expression were examined.Results: Six cell lines showed high MAPT mRNA expression and four showed high MAPT protein expression; that is, expression at the mRNA level did not always correlate with that at the protein level. MAPT mRNA expression did not correlate with taxane resistance, but expression of MAPT protein isoforms under 70 kDa correlated with taxane resistance. Downregulation of MAPT increased sensitivity to taxanes. MAPT protein expression was decreased by ER knockdown and increased by 17-β-estradiol stimulation. The MAPT protein level was also increased by tamoxifen, but decreased by ICI182,780. Combination treatment of taxanes with ICI182,780 showed a strong synergistic effect, but similar treatment with tamoxifen had an antagonistic effect in both cell lines.Conclusions: Expression of MAPT protein isoforms under 70 kDa correlates with taxane resistance in breast cancer cells. MAPT expression is influenced by ER in breast cancer and ICI182,780, a selective ER inhibitor, can reverse the resistance to taxanes in both MAPT- and ER-positive breast cancer. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 2118.

Microtubule Associated Protein Tau Expression as a Predictive and Prognostic Marker in a Trial Assessing Sequential Docetaxel as Adjuvant Chemotherapy for Early Breast Cancer (TACT).

Abstract Objective: TACT, which compared sequential anthracycline-taxane (FEC-D) adjuvant chemotherapy with an anthracycline regimen of similar duration (Lancet 2009:373, 1681-1692) provides an opportunity to correlate tau expression levels with disease-free survival (DFS) and to explore the interaction between tau expression and docetaxel benefit. Patients and Methods: 4162 patients were randomized to FE60C (fluorouracil, epirubicin and cyclophosphamide,- 4 cycles) followed by docetaxel (4 cycles) or control. Control, determined by local centres, was FE60C (8 cycles) or epirubicin (4 cycles) followed by classical CMF (cyclophosphamide, methotrexate and fluorouracil - 4 cycles). Patients with hormone receptor positive tumours also received adjuvant endocrine treatment. Tissue blocks were obtained for 3610 TACT patients (87 % of total) to create tissue microarrays (TMA). Tau protein expression was assessed by immunohistochemistry (IHC). Tau was successfully scored by 2 observers (blinded to treatment allocation and clinical outcome), scoring 2 cores from separate TMAs for each of 2977 patients. Intensity (negative, weak, moderate or strong) and the proportion of tumour cells stained (in 5% increments) were recorded. Results: A very strong association was observed between level of intensity and proportion of staining (p&amp;lt;0.001), subsequent analysis used tau intensity only. Fifty one percent of tumors were tau-positive defined as demonstrating weak or greater intensity of staining. Tau expression was positively correlated with ER status (p&amp;lt;0.001), negatively correlated with grade (p&amp;lt;0.001) and negatively correlated with HER2 status (p&amp;lt;0.001). In absence of overall treatment benefit for docetaxel, significant factors predicting DFS on univariate analysis were tau, ER and HER-2 expression in addition to nodal status, grade, tumour size and age. With the exception of age these variables were also significant on multivariate analysis. No significant interaction between tau expression and efficacy of docetaxel was observed in all patients or in patients within the ER+HER2-ve, HER2 +ve and ER -ve HER2 –ve subsets. Exploratory analyses to assess interactions using tau intensity and proportion IHC staining as continuous variables are underway and will be reported. Conclusion: Tau expression was associated with improved DFS but there was no evidence of an interaction between tau and docetaxel benefit. These results are similar to NSABP-B28, which evaluated addition of paclitaxel to doxorubicin/cyclophosphamide. Citation Information: Cancer Res 2009;69(24 Suppl):Abstract nr 607.

Differential effects of simvastatin and pravastatin on expression of Alzheimer's disease-related genes in human astrocytes and neuronal cells

Inhibitors of HMG-CoA reductase (statins) are widely used medications for reduction of cholesterol levels. Statin use significantly reduces risk of cardiovascular disease but has also been associated with lower risk of other diseases and conditions, including dementia. However, some reports suggest that statins also have detrimental effects on the brain. We provide evidence that simvastatin and pravastatin have significantly different effects on expression of genes related to neurodegeneration in astrocytes and neuroblastoma (SK-N-SH) cells in culture. Simvastatin significantly reduced expression of ABCA1 in astrocytes and neuroblastoma cells (by 79% and 97%, respectively; both P < 0.001). Pravastatin had a similar but attenuated effect on ABCA1 in astrocytes (-54%, P < 0.001) and neuroblastoma cells (-70%, P < 0.001). Simvastatin reduced expression of apolipoprotein E in astrocytes (P < 0.01). Furthermore, both statins reduced expression of microtubule-associated protein tau in astrocytes (P < 0.01), while both statins increased its expression in neuroblastoma cells (P < 0.01). In SK-N-SH cells, simvastatin significantly increased cyclin-dependent kinase 5 and glycogen synthase kinase 3beta expression, while pravastatin increased amyloid precursor protein expression. Our data suggest that simvastatin and pravastatin differentially affect expression of genes involved in neurodegeneration and that statin-dependent gene expression regulation is cell type specific.

Evaluation of microtubule associated protein tau expression as prognostic and predictive marker in the NSABP-B 28 randomized clinical trial.

Abstract Abstract #54 Objective: We assessed Tau protein expression in patients who participated in the National Surgical Breast and Bowel Project (NSABP)-B28 clinical trial using immunohistochemistry. Expression levels were correlated with disease-free (DFS) and overall survival (OS) and we also examined if there is interaction between this marker and paclitaxel efficacy. Patients and Methods: Tissue microarrays were available for 1942 patients (63 % of all trial participants) who were included in the NSABP-B28 clinical trial and were randomized to receive either 4 courses of doxorubicin/cyclophosphamide (AC) or AC followed by 4 additional courses of paclitaxel (ACT) adjuvant chemotherapy. All patients with hormone receptor positive tumors also received adjuvant endocrine treatment. Immunohistochemistry for Tau was performed at MD Anderson Cancer Center blinded to clinical outcome. Correlation with survival was performed by the NSABP Statistical Center. Results: Forty-three percent of tumors were Tau-positive defined as equal or greateer staining than in normal breast epithelium. Tau expression correlated strongly with estrogen receptor (ER)-positive status (p&amp;lt;0.0001). In univariate analyses, Tau, ER and HER-2 expression as well as grade, tumor size and nodal status were each independently and significantly associated with DFS and OS (p&amp;lt;0.003). In multivariate analysis, the same variables except HER2 remained significant. However, there was no significant interaction between Tau expression and benefit from paclitaxel in the entire population or among the ER-positive or ER-negative subsets, respectively. Conclusion: High Tau protein expression is associated with better prognosis including longer disease-free and overall survival in patients treated with adjuvant anthracyline and paclitaxel chemotherapy and endocrine therapy. However, we could not detect a statistically significant interaction between Tau expression and paclitaxel benefit. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 54.

Haplotypes and gene expression implicate the MAPT region for Parkinson disease

Microtubule-associated protein tau (MAPT) has been associated with several neurodegenerative disorders including forms of parkinsonism and Parkinson disease (PD). We evaluated the association of the MAPT region with PD in a large cohort of familial PD cases recruited by the GenePD Study. In addition, postmortem brain samples from patients with PD and neurologically normal controls were used to evaluate whether the expression of the 3-repeat and 4-repeat isoforms of MAPT, and neighboring genes Saitohin (STH) and KIAA1267, are altered in PD cerebellum. Twenty-one single-nucleotide polymorphisms (SNPs) in the region of MAPT on chromosome 17q21 were genotyped in the GenePD Study. Single SNPs and haplotypes, including the H1 haplotype, were evaluated for association to PD. Relative quantification of gene expression was performed using real-time RT-PCR. After adjusting for multiple comparisons, SNP rs1800547 was significantly associated with PD affection. While the H1 haplotype was associated with a significantly increased risk for PD, a novel H1 subhaplotype was identified that predicted a greater increased risk for PD. The expression of 4-repeat MAPT, STH, and KIAA1267 was significantly increased in PD brains relative to controls. No difference in expression was observed for 3-repeat MAPT. This study supports a role for MAPT in the pathogenesis of familial and idiopathic Parkinson disease (PD). Interestingly, the results of the gene expression studies suggest that other genes in the vicinity of MAPT, specifically STH and KIAA1267, may also have a role in PD and suggest complex effects for the genes in this region on PD risk.

Microtubule-associated protein tau is a marker of pathological complete response in Her-2/neu positive neoadjuvant treated breast cancer patients

Gene expression analysis in breast cancer patients undergoing neoadjuvant chemotherapy is an interesting tool for identification of gene signatures and new markers to predict tumor response. However, the detection of predictive markers strongly depends on the drugs used in the specific therapeutic setting. There is growing evidence that topoisomerase II-alpha (TOPO IIα) is a marker for anthracycline-, and microtubule-associated protein tau (MAPT) for taxane sensitivity. HER-2 has been described as a marker of both anthracycline and taxane sensitivity. We performed gene expression profiling of 50 patients within the GEPARTRIO study, an anthracycline and taxane neoadjuvant chemotherapy trial. Here we investigate the predictive value of TOPO IIα, MAPT and HER-2 mRNA expression for pathological complete response (pCR) in this setting. Interestingly, HER-2 gene expression was strongly predictive of pCR (P=0.017) as well as overall response (P=0.037) and clinical complete response (cCR, P=0.050). In contrast, for both TOPO IIα and MAPT no correlation with pCR was observed in our sample group.

Markers predicting clinical benefit in breast cancer from microtubule-targeting agents

Taxanes (e.g. paclitaxel, docetaxel) and epothilones (e.g. ixabepilone) are microtubule-targeting agents, which disrupt cellular processes and induce apoptosis. Although their mechanisms of action are similar, clinical data in breast cancer patients support at least partial non-cross resistance between the classes, and even between individual compounds. Several biomarkers might contribute to the identification of patient groups likely to derive benefit from one class of microtubule-targeting agent or even one agent. Overexpression of P-glycoprotein is associated with resistance to taxanes, but not ixabepilone, in vitro; its role in vivo remains unclear. Mutations in β-tubulin linked to resistance to taxanes but not epothilones are observed in vitro; somatic mutations of β-tubulin appear rare clinically. Overexpression of the βIII-tubulin isoform is associated with taxane resistance in cell lines; some clinical studies support a relationship between poor response to taxanes and overexpression of βIII-tubulin. βIII-tubulin overexpression seems not to affect sensitivity to ixabepilone [1]. Estrogen receptor negativity, low expression of microtubule-associated protein tau, and perhaps HER2 amplification may define a subset of patients with higher than average sensitivity to paclitaxel. Large scale pharmacogenomic analysis has identified molecular markers potentially capable of distinguishing patients with differential sensitivity to paclitaxel and ixabepilone. These markers require validation in clinical trials.

HER2 expression and efficacy of preoperative paclitaxel and 5-fluorouracil, cyclophosphamide, doxorubicin chemotherapy in breast cancer

548 Purpose: We examined the correlation between HER2 expression and pathologic complete response (pCR) to paclitaxel/FAC (T/FAC) preoperative chemotherapy in stage II-III breast cancer. Patients and Methods: Retrospective analysis of data including 534 patients treated with preoperative T/FAC was performed. Gene expression results were available from a subset of 132 patients and were used to examine the co-expression of HER2 and topoisomerase II a (TOP2A) and microtubule associated protein tau (MAP-Tau). Results: Of the 534 patients, 105 (20%) had HER2 overexpressing (HER2+) breast cancer. The pCR rates were 33% and 15% for patients with HER2+ and HER2- tumors (P&lt;0.001). The 5-year relapse-free survival rates were 94% and 70% in HER2+ tumors with and without pCR (P=0.009). In multivariate analysis ER-negative status (OR 3.1, 95% CI 1.7–5.5, P &lt; 0.001), high nuclear grade (OR 6.7, 95% CI 3.1–14.2, P &lt; 0.001), weekly paclitaxel regimen (OR 2.6, 95% CI 1.5–4.5, P &lt;0.001), and HER2 overexpression (OR 2.4, 95% CI 1.3–4.2, P = 0.003) were significant predictors of pCR. Among ER- cancers, the pCR rates were 50% (95%CI: 36–64%) in HER2+ (n=24/48) and 30% (95%CI: 23–37%) in HER2- disease (n=48/159), P = 0.02. Among ER+ cancers, the pCR rate was 19% (95% CI: 9–29%) in HER2+ (n=11/57) and 6% (95% CI: 3–9%) in HER2- disease (n=17/270), P = 0.003. In the gene expression data, HER2 overexpression was associated with lower expression of MAP-tau (mean 303 vs 500, p=0.001) and higher expression of TOP2A mRNAs (mean 398 vs 274, p=0.048) in patients with ER+ disease. All ER- cancers had low MAP-Tau expression (compared to ER+ cancers) regardless of HER2 status. Conclusion: HER2 overexpression is associated with higher rate of pCR to preoperative T/FAC chemotherapy in both ER- and ER+ cancers. HER2 overexpression correlates with increased TOP2A and decreased MAP-Tau expression in ER+ cancers which could explain increased anthracycline and taxane sensitivity of these tumors. No significant financial relationships to disclose.

Development of two novel benzoylphenylurea sulfur analogues and evidence that the microtubule-associated protein tau is predictive of their activity in pancreatic cancer

In this work, we evaluated two lead compounds, referred to as SG410 and SG430, obtained from a screen of sulfur benzoylphenylurea analogues, against in vitro and in vivo models of pancreas cancer. Both drugs showed a similar mechanism of action profile, with SG410 being more potent as an inhibitor of tubulin assembly. We determined the best in vivo administration schedule and tested SG410 and SG430 in nine cases of a novel platform of direct pancreas cancer xenografts. Both compounds had antiproliferative activity in vitro in the low nanomolar range, but only SG410 showed significant activity in vivo. Administration of SG410 resulted in significant tumor growth delay in five of nine groups tested. In a direct comparison in three of the cases, SG410 was at least as efficacious as docetaxel. We also sought markers that would be predictive of the efficacy of these agents, and we found such a marker in microtubule-associated protein tau (MAPT). This protein enhances the assembly and stability of microtubules. In both the cell lines and the direct human xenografts, MAPT mRNA and protein levels correlated well. There was also a statistically significant inverse correlation between MAPT expression and sensitivity to the tested agents. In summary, the novel sulfur benzoylphenylurea SG410 showed activity inversely related to MAPT expression in a preclinical model of pancreatic cancer comparable with that observed with docetaxel, another microtubule-targeting agent.

Haplotype-specific expression of exon 10 at the human MAPT locus

Neurofibrillary tangles composed of exon 10+ microtubule associated protein tau (MAPT) deposits are the characteristic feature of the neurodegenerative diseases progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD). PSP, CBD and more recently Alzheimer's disease and Parkinson's disease, are associated with the MAPT H1 haplotype, but the relationship between genotype and disease remains unclear. Here, we investigate the hypothesis that H1 expresses more exon 10+ MAPT mRNA compared to the other haplotype, H2, leading to a greater susceptibility to neurodegeneration in H1 carriers. We performed allele-specific gene expression on two H1/H2 heterozygous human neuronal cell lines, and 14 H1/H2 heterozygous control individual post-mortem brain tissue from two brain regions. In both tissue culture and post-mortem brain tissue, we show that the MAPT H1 haplotype expresses significantly more exon 10+ MAPT mRNA than H2. In post-mortem brain tissue, we show that the total level of MAPT expression from H1 and H2 is not significantly different, but that the H1 chromosome expresses up to 1.43-fold more exon 10+ MAPT mRNA than H2 in the globus pallidus, a brain region highly affected by tauopathy (maximum exon 10+ MAPT H1:H2 transcript ratio=1.425, SD=0.205, P<0.0001), and up to 1.29-fold more exon 10+ MAPT mRNA than H2 in the frontal cortex (maximum exon 10+ MAPT H1:H2 transcript ratio=1.291, SD=0.315, P=0.006). These data may explain the increased susceptibility of H1 carriers to neurodegeneration and suggest a potential mechanism between MAPT genetic variability and the pathogenesis of neurodegenerative disease.

Effects of EGF and bFGF on expression of microtubule-associated protein tau and MAP-2 mRNA in human umbilical cord mononuclear cells

The aim of this study was to explore the regulatory effects of cytokines, such as EGF and bFGF, on expression of the neural-specific molecules tau and MAP2 mRNA in mononuclear cells (MNCs) derived from human umbilical cord blood (UCB). Phenotypic changes were monitored by inverse phase-contrast microscopy. Tau and MAP2 mRNA were determined by reverse-transcriptase polymerase chain reaction (RT-PCR). Tau and MAP2-positive cells were determined by immunocytochemistry. The expression of tau mRNA was negative in uncultured cells, but MAP2 mRNA was positive; in cultured cells, tau protein mRNA expression was positive, MAP2 mRNA expression was upregulated by EGF+bFGF, EGF and bFGF compared to the control group (no cytokines). EGF+bFGF had a greater effect on MAP2 mRNA expression than EGF or bFGF alone. The same upregulatory tendency was noted for tau mRNA expression. It is concluded that MNCs derived from human UCB cells may express some neural specific molecules that can be upregulated by cytokines, especially EGF and bFGF together.