Tau Protein Expression Research Articles

Correlation between Tau expression and clinicopathological characteristics of breast invasive ductal carcinomas

To explore the expression of Tau protein in breast invasive ductal carcinomas and examine the correlation between its expression and clinicopathological characteristics of breast cancer. The clinicopathological data of 150 breast cancer patients at Third Municipal Hospital from October 2007 to June 2011 were collected and analyzed. Immunohistochemical method was used to detect the expressions of estrogen receptor (ER), progesterone receptor (PR), HER-2 and Tau protein. No correlations existed between the expression of Tau protein and age, tumor size or node metastasis of breast cancer patients (χ(2) = 0.02, P = 0.88; χ(2) = 0.55, P = 0.46; χ(2) = 1.02, P = 0.31). The expressions of Tau in ER positive patients were significantly higher than ER negative patients. And this trend extended to PR positive and HER-2 negative patients (χ(2) = 15.77, P = 0.00; χ(2) = 5.03, P = 0.03; χ(2) = 8.00, P = 0.01). The expression of Tau protein in Luminal A subtype was significantly higher than in Luminal B subtype, HER-2 over-expression subtype and basal like subtype (χ(2) = 7.26, P = 0.01). Over-expressed in breast cancer, Tau protein is associated with ER, PR and HER-2. However, the relation between Tau protein and prognosis of breast cancer requires further researches.

Effects of sirolimus on scopolamine-induced cognitive dysfunction in rats

Objective To evaluate the effects of sirolimus on scopolamine-induced cognitive dysfunction in rats.Methods Thirty male Wistar rats,aged 3 months,weighing 200-250 g,were equally randomized into 3 groups:normal saline group (NS group),scopolamine group (SC group) and scopolamine + sirolimus group (SS group).Normal saline,scopolamine 0.8 mg/kg and sirolimus 3.5 mg/kg + scopolamine 0.8 mg/kg were injected intraperitoneally in groups NS,SC and SS,respectively,and the injection was continued for 14 consecutive days.The cognitive function was assessed by Morris water maze test on 15th day.After behavior test,the rats were sacrificed and the prefrontal cortex and hippocampus were harvested for determination of amyloid β protein (Aβ) and Tau protein expression.Results Compared with NS group,the escape latency was significantly prolonged,the ratio of time spent in the target quadrant was decreased,Aβ expression in prefrontal cortex and hippocampus was upregulated and Tau protein expression in prefrontal cortex and hippocampus was down-regulated in group SC (P ＜0.05 or 0.01).Compared with SC group,the escape latency was significantly shortened,the ratio of time spent in the target quadrant was increased,Aβ expression in prefrontal cortex and hippocampus was down-regulated and Tau protein expression in prefrontal cortex and hippocampus was up-regulated in group SS (P ＜ 0.05 or 0.01).Conclusion Sirolimus can significantly improve scopolamine-induced cognitive dysfunction in rats and the changes in the expression of Aβ and Tau protein in prefrontal cortex and hippocampus may be involved in the mechanism. Key words: Sirolimus; Scopolamine; Cognition disorders

NMDA receptor subunit composition determines beta-amyloid-induced neurodegeneration and synaptic loss

Aggregates of amyloid-beta (Aβ) and tau are hallmarks of Alzheimer's disease (AD) leading to neurodegeneration and synaptic loss. While increasing evidence suggests that inhibition of N-methyl-𝒟-aspartate receptors (NMDARs) may mitigate certain aspects of AD neuropathology, the precise role of different NMDAR subtypes for Aβ- and tau-mediated toxicity remains to be elucidated. Using mouse organotypic hippocampal slice cultures from arcAβ transgenic mice combined with Sindbis virus-mediated expression of human wild-type tau protein (hTau), we show that Aβ caused dendritic spine loss independently of tau. However, the presence of hTau was required for Aβ-induced cell death accompanied by increased hTau phosphorylation. Inhibition of NR2B-containing NMDARs abolished Aβ-induced hTau phosphorylation and toxicity by preventing GSK-3β activation but did not affect dendritic spine loss. Inversely, NR2A-containing NMDAR inhibition as well as NR2A-subunit knockout diminished dendritic spine loss but not the Aβ effect on hTau. Activation of extrasynaptic NMDARs in primary neurons caused degeneration of hTau-expressing neurons, which could be prevented by NR2B–NMDAR inhibition but not by NR2A knockout. Furthermore, caspase-3 activity was increased in arcAβ transgenic cultures. Activity was reduced by NR2A knockout but not by NR2B inhibition. Accordingly, caspase-3 inhibition abolished spine loss but not hTau-dependent toxicity in arcAβ transgenic slice cultures. Our data show that Aβ induces dendritic spine loss via a pathway involving NR2A-containing NMDARs and active caspase-3 whereas activation of eSyn NR2B-containing NMDARs is required for hTau-dependent neurodegeneration, independent of caspase-3.

Relationship Between Gastric Cancer Tau Protein Expression and Paclitaxel Sensitivity

The abnormal expression of Tau protein in breast cancer tissue affects paclitaxel sensitivity. The abnormal expression also exists in gastric carcinoma. Therefore, we speculate that the expression levels of Tau protein is closely related to paclitaxel sensitivity in gastric cancer, thus affecting the efficacy of paclitaxel. In this study, we used immunohistochemical methods to detect Tau protein expression levels in 47 cases of gastric cancer specimens. We also used Western blot to detect the level of Tau protein expression in gastric cancer cell lines and to check the efficacy of paclitaxel in vitro application. Findings indicate that Tau protein expression rate can reach as high as (+ +-+ + +) 63.83% in gastric cancer. Paclitaxel induces inhibition and apoptosis with low expression of Tau protein in gastric cancer cell lines (P < 0.05). The level of Tau protein expression is significantly correlated with paclitaxel efficacy. If confirmed by further studies, the Tau protein can be another useful marker of gastric cancer, thereby leading to the application of paclitaxel in cancer treatment.

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.

Okadaic acid-induced Tau phosphorylation in rat brain: Role of NMDA receptor

Okadaic acid (OKA) is a potent inhibitor of protein phosphatases 1/2A (PP2A). Inhibition of PP2A leads to hyperphosphorylation of Tau protein. Hyperphosphorylated Tau protein is present in intraneuronal neurofibrillary tangles a characteristic feature of neuropathology of Alzheimer’s disease. Intracerebroventricular (ICV) administration of OKA causes neurotoxicity, which is associated with increased intracellular Ca2+ level, oxidative stress, and mitochondrial dysfunction in the brain areas. The present study explored Tau phosphorylation in OKA-treated rats in relation to memory function, PP2A activity, intracellular Ca2+, glycogen synthase kinase-3β (GSK-3β) and N-methyl-d-aspartate (NMDA) receptor after 13days of OKA (200ng, ICV) administration in rats, memory was found impaired in the water maze test. OKA-induced memory-impaired rats showed increased mRNA and protein expression of Tau, Ca2+/calmodulin-dependent protein kinase II (CaMKII), Calpain and GSK3β in the hippocampus and cerebral cortex. On the other hand, mRNA expression and activity of PP2A was reduced in these brain areas. OKA treatment also, resulted in decrease in mRNA expression of C and N terminals of Tau. Treatment with NMDA antagonist, MK801 (0.05mg/kg, i.p.) for 13days significantly prevented OKA-induced changes in the expression of PP2A, Tau, GSK3β, CaMKII and Calpain. Further, daily administration of anticholinergic drug, donepezil (5mg/kg, p.o.), and the NMDA receptor antagonist, memantine (10mg/kg, p.o.) initiated after OKA administration for 13days significantly attenuated OKA-induced variation in Tau, Tau-C terminal, Tau-N terminal CaMKII, Calpain, PP2A and GSK3β. These results infer that NMDA antagonist MK801 and memantine are effective against OKA-induced neurotoxicity. Therefore, the present study clearly indicates the involvement of NMDA receptor in OKA (ICV)-induced Tau hyperphosphorylation.

Cellular and molecular mechanisms underlying the action of ginsenoside Rg1 against Alzheimer's disease.

Ginsenoside Rg1 inhibits oxidation, aging and cell apoptosis, and improves cognitive function. In this study, we pretreated rat brain tissue sections with ginsenoside Rg1, and established brain slice models of Alzheimer’s disease induced by okadaic acid. The results revealed that ginsenoside Rg1 pretreatment suppressed the increase in phosphorylated Tau protein expression induced by incubation with okadaic acid, and reduced brain-derived neurotrophic factor expression. These results suggest that ginsenoside Rg1 upregulates brain-derived neurotrophic factor expression and inhibits Tau protein phosphorylation in brain slices from a rat model of Alzheimer’s disease.

Secondary RNA structure and nucleotide specificity contribute to internal initiation mediated by the human tau 5′ leader

Mechanisms by which eukaryotic internal ribosomal entry sites (IRESs) initiate translation have not been well described. Viral IRESs utilize a combination of secondary/tertiary structure concomitant with sequence specific elements to initiate translation. Eukaryotic IRESs are proposed to utilize the same components, although it appears that short sequence specific elements are more common. In this report we perform an extensive analysis of the IRES in the human tau mRNA. We demonstrate that the tau IRES exhibits characteristics similar to viral IRESs. It contains two main structural domains that exhibit secondary interactions, which are essential for internal initiation. Moreover, the tau IRES is extremely sensitive to small nucleotide substitutions. Our data also indicates that the 40S ribosome is recruited to the middle of the IRES, but whether it scans to the initiation codon in a linear fashion is questioned. Overall, these results identify structural and sequence elements critical for tau IRES activity and consequently, provide a novel target to regulate tau protein expression in disease states including Alzheimer disease and other tauopathies.

Tau expression correlated with breast cancer sensitivity to taxanes-based neoadjuvant chemotherapy

The purpose of this study was to investigate the correlation between tau expression in primary breast cancer and sensitivity to taxanes during neoadjuvant chemotherapy in patients with breast cancer. We used immunohistochemistry to examine tau expression in breast cancer biopsies from 113 primary breast cancer patients and evaluated the correlation between tau expression and taxane sensitivity. Twenty-eight (24.78%, 28/113) patients were positive for tau expression. After taxanes-based neoadjuvant chemotherapy, 40 patients achieved pathological complete response (pCR) (35.4%). Among the 40 patients with pCR, five (12.5%) were positive for tau expression. In univariate analysis, estrogen receptor (ER), progesterone receptor, human epidermal growth factor receptor 2 (HER2), and tau were found to be significantly predictive of a pCR (P = 0.001, 0.030, 0.002, and 0.025, respectively). Tau, ER, and HER2 status were significant for pCR on multivariate analysis (P = 0.025, 0.005, and 0.043, respectively). Tau expression was positively related to ER (P = 0.007) and progestin receptor (P = 0.008). In conclusion, tau protein expression correlated with breast cancer sensitivity to taxanes-based neoadjuvant chemotherapy; patients negative for tau expression were more likely to achieve pCR.

The Synaptic Accumulation of Hyperphosphorylated Tau Oligomers in Alzheimer Disease Is Associated With Dysfunction of the Ubiquitin-Proteasome System

In Alzheimer disease (AD), deposition of neurofibrillary tangles and loss of synapses in the neocortex and limbic system each correlate strongly with cognitive impairment. Tangles are composed of misfolded hyperphosphorylated tau proteins; however, the link between tau abnormalities and synaptic dysfunction remains unclear. We examined the location of tau in control and AD cortices using biochemical and morphologic methods. We found that, in addition to its well-described axonal localization, normal tau is present at both presynaptic and postsynaptic terminals in control human brains. In AD, tau becomes hyperphosphorylated and misfolded at both presynaptic and postsynaptic terminals, and this abnormally posttranslationally modified tau is enriched in synaptoneurosomal fractions. Synaptic tau seems to be hyperphosphorylated and ubiquitinated, and forms stable oligomers resistant to SDS denaturation. The accumulation of hyperphosphorylated tau oligomers at human AD synapses is associated with increased ubiquitinated substrates and increased proteasome components, consistent with dysfunction of the ubiquitin-proteasome system. Our findings suggest that synaptic hyperphosphorylated tau oligomers may be an important mediator of the proteotoxicity that disrupts synapses in AD.

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.

Human fetal tau protein isoform: Possibilities for Alzheimer's disease treatment

While early 1990s reports showed the phosphorylation pattern of fetal tau protein to be similar to that of tau in paired helical filaments (PHF) in Alzheimer's disease (AD), neither the molecular mechanisms of the transient developmental hyperphosphorylation of tau nor reactivation of the fetal plasticity due to re-expression of fetal protein kinases in the aging and AD human brain have been sufficiently investigated. Here, we summarize the current knowledge on fetal tau, adding new data on the specific patterns of tau protein and mRNA expression in the developing human brain as well as on change in tau phosphorylation in the perforant pathway after entorhinal cortex lesion in mice. As fetal tau isoform does not form PHF even in a highly phosphorylated state, understanding its expression and post-translational modifications represents an important avenue for future research towards the development of AD treatment and prevention.

Effect of propofol anesthesia on electroconvulsive therapy-induced hyperphosphorylation of Tau protein in hippocampus in depressed rats

Objective To investigate the effect of propofol anesthesia on electroconvulsive therapy (ECT)-induced hyperphosphorylation of Tau protein in hippocampus in depressed rats.Methods Thirty-two female WYK rats in which the total score was 30-120 after Open-field test,aged 24 weeks,weighing 200-250 g,were randomly divided into 4 groups ( n =8 each):control group (group C),propofol group (group P),ECT group (group E)and propofol + ECT group (group PE).In groups C and E,the animals received intraperitoneal normal saline 5 ml,and in addition the animals received ECT 15 min later in group E.In groups P and PE,the animals received intraperitoneal 100 mg/kg propofol 5 ml,and in addition the animals received ECT 15 min later in group PE.The learning and memory function was assessed by Morris water maze test at 24 h after ECT.The animals were sacririced at 6 h after Morris water maze test and the hippocampal tissues were removed for determination of the expression of phosphorylated Tau protein.Results Compared with group C,the escape latency was significantly prolonged,the swimming time was significantly shortened in groups P,E and PE,the expression of phosphorylated Tau protein in hippocampus was down-regulated in group P,and the expression of phosphorylated Tau protein in hippocampus was up-regulated in group E ( P ＜ 0.05).Compared with group E,the escape latency was significantly shortened,the swimming time was significantly prolonged,and the expression of phosphorylated Tau protein in hippocampus was down-regulated in group PE (P ＜0.05).Conclusion The mechanism by which propofol anesthesia improves cognitive impairment induced by ECT may be related to inhibition of hyperphosphorylation of Tau protein in hippocampus in depressed rats. Key words: Propofol; Electroconvulsive therapy; Depression; tau proteins; Hippocampus

In vitro and in vivo comparisons of the effects of the fruiting body and mycelium of Antrodia camphorata against amyloid β-protein-induced neurotoxicity and memory impairment

Antrodia camphorata is a particular and precious medicinal mushroom, and its fruiting body was found to provide more efficient protection from oxidative stress and inflammation than its mycelium because of its higher content of triterpenoids, total phenols, and so on. In the previous in vitro studies, the mycelium of A. camphorata is proven to provide strong neuroprotection in neuron cells and suggested to have the potential of protection against neurotoxicity of amyloid β-protein (Aβ) known as the risk factor toward Alzheimer's disease (AD) development. However, the in vivo study and the comparison study with the fruiting body have not yet been investigated. This study compared the effect of the fruiting body and mycelium of A. camphorata on alleviating the Aβ40-induced neurocytotoxicity in the in vitro Aβ-damaged neuron cell model (PC-12 cell treated with Aβ40) and memory impairment in the in vivo AD animal model induced with a continuous brain infusion of Aβ40. In the results of in vitro and in vivo studies, the fruiting body possessed stronger anti-oxidative and anti-inflammatory abilities for inhibiting neurocytotoxicity in Aβ40-treated PC-12 cells and Aβ40 accumulation in Aβ40-infused brain than mycelium. Moreover, hyperphosphorylated tau (p-tau) protein expression, known as an important AD risk factor, was suppressed by the treatment of fruiting body rather than that of mycelium in the in vitro and in vivo studies. These comparisons supported the reasons why the fruiting body resulted in a more significant improvement effect on working memory ability than mycelium in the AD rats.

Supplementation of Convolvulus pluricaulis attenuates scopolamine-induced increased tau and Amyloid precursor protein (AβPP) expression in rat brain

Aim:Scopolamine is known to produce amnesia due to blockade of the cholinergic neurotransmission. The present study investigated the potential of Convolvulus pluricaulis (CP) to attenuate scopolamine (2 mg/kg, i.p) induced increased protein and mRNA levels of tau, amyloid precursor protein (AβPP), amyloid β (Aβ) levels and histopathological changes in rat cerebral cortex.Materials and Methods:The study was conducted on male Wistar rats (250 ± 20 g) divided into four groups of eight animals each. Groups 1 and 2 served as controls receiving normal saline and scopolamine for 4 weeks, respectively. Group 3 received rivastigmine (standard) and group 4 received aqueous extract of CP simultaneously with scopolamine. Western blot and RT-PCR analysis were used to evaluate the levels of protein and mRNA of amyloid precursor protein (AβPP) and tau in rat cortex and ELISA was used to measure the amyloid β (Aβ) levels. Histopathology was also performed on cortical section of all groups.Result:Oral administration of CP extract (150 mg/kg) to scopolamine treated rats reduced the increased protein and mRNA levels of tau and AβPP levels followed by reduction in Aβ levels compared with scopolamine treated group. The potential of extract to prevent scopolamine neurotoxicity was reflected at the microscopic level as well, indicative of its neuroprotective effects.Conclusion:CP treatment alleviated neurotoxic effect of scopolamine reflects its potential as potent neuroprotective agent.

Tau protein is involved in morphological plasticity in hippocampal neurons in response to BDNF

Tau protein, a microtubule-associated protein involved in a number of neurological disorders such as Alzheimer’s disease (AD), may undergo modifications under both physiological and pathological conditions. However, the signaling pathways that couple tau protein to neuronal physiology such as synaptic plasticity have not yet been elucidated. Here we report that tau protein is involved in morphological plasticity in response to brain derived neurotrophic factor (BDNF). Stimulation of the cultured rat hippocampal neurons with BDNF resulted in increased tau protein expression, as detected by Western blotting. Furthermore, tau protein accumulated in the distal region of the neurite when treated with taxol or taxol plus BDNF. The increased tau protein also protected neurons against nocodazole-induced dendrite loss. Moreover, BDNF promoted spine growth as well as tau protein over-expression. Knockdown of tau protein using specific short-hairpin RNA (shRNA) significantly decreased the spine density. And BDNF could not increase the spine density of tau-knockdown neurons. These results highlight a possible role for tau protein in the dynamic rearrangement of cytoskeletal fibers vital for BDNF-induced synaptic plasticity.

P5-13-11: PTEN and Tau-Protein Expression: Predictive Value of Poor Response to Trastuzumab Plus Paclitaxel in Patients with HER2−Positive Breast Cancer.

Abstract Backgrounds: Trastuzumab-based chemotherapy has been an active treatment in patients (pts) with HER2−positive breast cancer; however, primary and secondary resistance has occurred in pts treated with trastuzumab (H) alone or in combination with chemotherapy. Material and Methods: Biomarkers were searched using tissue microarrays (TMA) in the HER2−positive breast cancer pts treated with H and paclitaxel (P) combination chemotherapy between October 2004 and August 2010. Tumor blocks of 101 pts were analyzed for VEGF, IGF-1R, p-Akt, beta-III tubulin, CD44, Tau-protein, p27 and PTEN by immunohistochemical (IHC) analysis. Eight biomarkers were assessed to investigate the correlation with the clinical outcomes, including response rate (RR), progression free survival (PFS), and overall survival (OS). Results: With a median follow-up duration of 21.7 months (range, 9.1−55.2 months), 101 pts received H+P chemotherapy in neoadjuvant setting (n=36, 35.6%) and recurrent or metastatic setting (n=65, 64.4%). Median age was 48 (range, 19–83 years), and the majority of pts (n=95, 94.1%) had good performance status. Premenopausal pts and hormone receptor-negative pts were 48 (47.5%) and 52 (51.5%), respectively. The median cycle of H+P chemotherapy was six (range, H 1–43; P 1–21). Overall RR was 68.3% (n=69) including complete response with 7 pts, and PFS and OS were significantly longer in pts responsive to H+P chemotherapy compared with non-responsive patients (PFS, p=0.001; OS, p=0.015). Although VEGF, IGF-1R, p-Akt, beta-III tubulin, CD44, p27 and PTEN status by IHC were not significantly associated with response to H+P chemotherapy, Tau-protein showed a trend of association without statistical significance (RR, 46.2% vs. 71.6%, p=0.066). Among 13 pts with high Tau protein expression, 9 pts with both high Tau-protein and low PTEN level showed statistically significant lower RR compared with other 92 pts (22.2% vs. 72.8%; p=0.002). None of the biomarkers was related to PFS and OS in pts with recurrent or metastatic disease, and to pathologic complete response in pts after H+P chemotherapy as neoadjuvant therapy. Conclusion: Our data showed that both low PTEN level and high Tauprotein expression were significantly associated with poor response to H+P chemotherapy in patients with HER2−positive breast cancer. Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P5-13-11.

Gene pathways associated with prognosis and chemotherapy sensitivity in different molecular subtypes of breast cancer

Breast cancer consists of multiple different molecular subtypes and different biological processes, and consequently different molecular markers are associated with prognosis and chemotherapy sensitivity in the distinct disease subsets [1]. A large number of biological processes including cell cycle regulation, DNA replication, mitotic spindle checkpoint, and p53 function are strongly prognostic in ER+ cancers but not among ER- cancers [2,3]. Interestingly, the number of biological pathways, and therefore genes, that are associated with prognosis or treatment sensitivity are substantially larger and more consistent in ER+ cancers than among ER- tumors [1,4]. This implies that it is easier to discover prognostic and predictive markers for ER+ than for ER- cancers. In ER- cancers, the single most consistent, but still modestly accurate, good prognostic predictor is the presence of immune cell infiltration [5]. Immune cell signatures are also associated with more favorable prognosis in highly proliferative ER+ cancers but not in ER+ cancers with low proliferation [6]. It is also increasingly clear that the same molecular marker can be associated with several different outcome endpoints in various and often opposing manners. For example, high Ki67 expression is predictive of worse prognosis in the absence of any systemic therapy in ER+ cancers, but at the same time it is also predictive of higher sensitivity to chemotherapy. Similar opposing bidirectional associations with treatment response and prognosis exist for many other markers including histologic grade, Tau protein expression and almost all prognostic gene signatures [7]. It is important to be aware of these complex multi-directional interactions between molecular markers and various clinical endpoints that may also vary from breast cancer subtype to subtype. Ignoring these potential marker-disease subset-outcome interactions can lead to contradictory and confusing results across studies (due to differences in patient composition and heterogeneity of therapy between studies) and may also lead to the discovery of biomarkers that are clinically less useful (because of unrecognized subtype-restricted performance) [8,9].

Predictive Value of Microtubule Associated Proteins Tau and Stathmin in Patients With Nonmuscle Invasive Bladder Cancer Receiving Adjuvant Intravesical Taxane Therapy

After encouraging results from 2 clinical trials performed at our institution to test intravesical taxane based chemotherapy for bacillus Calmette-Guérin refractory, nonmuscle invasive bladder cancer we designed a study to identify molecular markers linked to the optimal response to such treatment modality. Included in the institutional review board approved study were 32 patients with nonmuscle invasive, bacillus Calmette-Guérin refractory bladder cancer who received intravesical taxane chemotherapy, that is docetaxel or nanoparticle albumin-bound paclitaxel. Immunophenotype analysis on tissue samples obtained before intravesical taxane therapy was done using a panel of molecular markers, including Ki-67, p53, and the microtubule associated proteins tau and stathmin. Increased total tau (cytoplasmic and nuclear) and stathmin expression before intravesical taxane therapy was significantly associated with decreased recurrence-free survival (p <0.0001 and 0.007, respectively). A tau positive phenotype was an independent prognostic factor for recurrence-free survival on multivariate analysis (HR 15.66, 95% CI 2.68-91.71, p = 0.002). Neither the proliferation index assessed by Ki-67 expression nor p53 status was significantly associated with recurrence-free survival. Assessment of tau and stathmin protein expression should be considered to select patients before intravesical taxane based chemotherapy for nonmuscle invasive, bacillus Calmette-Guérin refractory bladder cancer since those who have tumors with low tau/stathmin protein expression show a better response to therapy.

Insulin-induced neurite-like process outgrowth: Acceleration of tau protein synthesis via a phosphoinositide 3-kinase∼mammalian target of rapamycin pathway

Both insulin and tau, promoting neuronal differentiation (neurite outgrowth, neuronal polarity, and myelination) and cell survival, are associated with neurodegenerative disease (e.g., Alzheimer’s disease). The aim of this study was to explore relation between insulin-induced activation of insulin signal and expression of tau protein on neurite-like process outgrowth in adrenal chromaffin cells. Primary cultured bovine adrenal chromaffin cells were incubated with insulin to determine whether stimulant of insulin signal could affect tau expression and neurite-like process outgrowth. Chronic treatment with insulin (⩾6 h) led neurite-like process outgrowth as well as increased tau protein level by ∼99% in a concentration (EC 50 5.5 nM)- and time-dependent manner, without changing Ser 396-phosphorylated tau level. The insulin-induced increase of tau protein level was abolished by LY294002 [an inhibitor of phosphoinositide 3-kinase (PI3K)] and rapamycin [an inhibitor of mammalian target of rapamycin (mTOR)], but not by PD98059 and U0126 [two inhibitors of mitogen-activated protein kinase/extracellular signal-regulated kinase (MEK)]. Additionally, insulin-induced increase of tau was blocked by cyclohexamide (an inhibitor of protein synthesis), but not by actinomycin D (an inhibitor of gene transcription). Pulse-label followed by polyacrylamide gel electrophoresis revealed that insulin accelerated tau protein synthesis rate (t 1/2) from 2.6 to 1.9 h. Insulin did not change tau mRNA level. Taken together, these results suggest that insulin-induced activation of PI3K∼mTOR pathway up-regulated tau protein via acceleration of protein synthesis, on which insulin promoted neurite-like process outgrowth.