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

Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Cancer-specific association between Tau (MAPT) and cellular pathways, clinical outcome, and drug response

Tau (MAPT) is a microtubule-associated protein causing common neurodegenerative diseases or rare inherited frontotemporal lobar degenerations. Emerging evidence for non-canonical functions of Tau in DNA repair and P53 regulation suggests its involvement in cancer. To bring new evidence for a relevant role of Tau in cancer, we carried out an in-silico pan-cancer analysis of MAPT transcriptomic profile in over 10000 clinical samples from 32 cancer types and over 1300 pre-clinical samples from 28 cancer types provided by the TCGA and the DEPMAP datasets respectively. MAPT expression associated with key cancer hallmarks including inflammation, proliferation, and epithelial to mesenchymal transition, showing cancer-specific patterns. In some cancer types, MAPT functional networks were affected by P53 mutational status. We identified new associations of MAPT with clinical outcomes and drug response in a context-specific manner. Overall, our findings indicate that the MAPT gene is a potential major player in multiple types of cancer. Importantly, the impact of Tau on cancer seems to be heavily influenced by the specific cellular environment.

Breast cancer patient-derived microtumors resemble tumor heterogeneity and enable protein-based stratification and functional validation of individualized drug treatment

Despite tremendous progress in deciphering breast cancer at the genomic level, the pronounced intra- and intertumoral heterogeneity remains a major obstacle to the advancement of novel and more effective treatment approaches. Frequent treatment failure and the development of treatment resistance highlight the need for patient-derived tumor models that reflect the individual tumors of breast cancer patients and allow a comprehensive analyses and parallel functional validation of individualized and therapeutically targetable vulnerabilities in protein signal transduction pathways. Here, we introduce the generation and application of breast cancer patient-derived 3D microtumors (BC-PDMs). Residual fresh tumor tissue specimens were collected from n = 102 patients diagnosed with breast cancer and subjected to BC-PDM isolation. BC-PDMs retained histopathological characteristics, and extracellular matrix (ECM) components together with key protein signaling pathway signatures of the corresponding primary tumor tissue. Accordingly, BC-PDMs reflect the inter- and intratumoral heterogeneity of breast cancer and its key signal transduction properties. DigiWest®-based protein expression profiling of identified treatment responder and non-responder BC-PDMs enabled the identification of potential resistance and sensitivity markers of individual drug treatments, including markers previously associated with treatment response and yet undescribed proteins. The combination of individualized drug testing with comprehensive protein profiling analyses of BC-PDMs may provide a valuable complement for personalized treatment stratification and response prediction for breast cancer.

Tau Protein as Therapeutic Target for Cancer? Focus on Glioblastoma

Despite being extensively studied for several decades, the microtubule-associated protein Tau has not finished revealing its secrets. For long, Tau has been known for its ability to promote microtubule assembly. A less known feature of Tau is its capability to bind to cancer-related protein kinases, suggesting a possible role of Tau in modulating microtubule-independent cellular pathways that are associated with oncogenesis. With the intention of finding new therapeutic targets for cancer, it appears essential to examine the interaction of Tau with these kinases and their consequences. This review aims at collecting the literature data supporting the relationship between Tau and cancer with a particular focus on glioblastoma tumors in which the pathological significance of Tau remains largely unexplored. We will first treat this subject from a mechanistic point of view showing the pivotal role of Tau in oncogenic processes. Then, we will discuss the involvement of Tau in dysregulating critical pathways in glioblastoma. Finally, we will outline promising strategies to target Tau protein for the therapy of glioblastoma.

Systemic therapy for early-stage breast cancer: learning from the past to build the future

The treatment of breast cancer has improved dramatically over the past century, from a strictly surgical approach to a coordinated one, including local and systemic therapies. Systemic therapies for early-stage disease were initially tested against observation or placebo only in adjuvant trials. Subsequent clinical trials focusing on treatment ‘fine-tuning’ had a marked increase in cohort size, duration and costs, leading to a growing interest in the neoadjuvant setting in the past decade. Neoadjuvant trial designs have the advantages of enabling the direct evaluation of treatment effects on tumour diameter and offer unique translational research opportunities through the comparative analysis of tumour biology before, during and after treatment. Current technologies enabling the identification of better predictive biomarkers are shaping the new era of (neo)adjuvant trials. An urgent need exists to reinforce collaboration between the pharmaceutical industry and academia to share data and thus establish large databases of biomarker data coupled with patient outcomes that are easily accessible to the scientific community. In this Review, we summarize the evolution of (neo)adjuvant trials from the pre-genomic to the post-genomic era and provide critical insights into how neoadjuvant studies are currently designed, discussing the need for better end points and treatment strategies that are more personalized, including in the post-neoadjuvant setting.

Systemic therapies for early-stage disease have been tested in clinical trials for decades. The authors of this Review provide an overview of the evolution of (neo)adjuvant trials from the pre-genomic to the post-genomic era, focusing on design, end points and biomarkers that, together, could enable the delivery of more personalized treatment.

Systemic therapy for patients with early-stage breast cancer has dramatically improved over the past eight decades, and the aims and designs of (neo)adjuvant clinical trials have consistently evolved.

The transition of clinical trials from the pre-genomic to the post-genomic era has been based on a deeper understanding of disease biology and a higher level of interest in the discovery of molecular markers associated with a response to treatment.

The currently adopted approach to the design of neoadjuvant trials requires a new wave of changes, with the implementation of validated end points with more robust predictive associations with survival outcomes and more personalized treatment strategies (escalation and/or de-escalation).

The evolution towards a more personalized treatment approach is leading to increasing interest in the post-neoadjuvant setting to investigate new drugs specifically in patients with high-risk disease.

Optimizing the efficiency of the search for novel biomarkers that can guide treatment tailoring requires the establishment of large, well-annotated databases of candidate biomarkers linked with clinical outcomes that are also easily accessible to the scientific community.

Early sharing of data from clinical trials should be based on joint efforts and reinforced collaboration between the pharmaceutical industry and academic entities.

Gastric cancer biomarker analysis in patients treated with different adjuvant chemotherapy regimens within SAMIT, a phase III randomized controlled trial

Biomarkers for selecting gastric cancer (GC) patients likely to benefit from sequential paclitaxel treatment followed by fluorinated-pyrimidine-based adjuvant chemotherapy (sequential paclitaxel) were investigated using tissue samples of patients recruited into SAMIT, a phase III randomized controlled trial. Total RNA was extracted from 556 GC resection samples. The expression of 105 genes was quantified using real-time PCR. Genes predicting the benefit of sequential paclitaxel on overall survival, disease-free survival, and cumulative incidence of relapse were identified based on the ranking of p-values associated with the interaction between the biomarker and sequential paclitaxel or monotherapy groups. Low VSNL1 and CD44 expression predicted the benefit of sequential paclitaxel treatment for all three endpoints. Patients with combined low expression of both genes benefitted most from sequential paclitaxel therapy (hazard ratio = 0.48 [95% confidence interval, 0.30-0.78]; p < 0.01; interaction p-value < 0.01). This is the first study to identify VSNL1 and CD44 RNA expression levels as biomarkers for selecting GC patients that are likely to benefit from sequential paclitaxel treatment followed by fluorinated-pyrimidine-based adjuvant chemotherapy. Our findings may facilitate clinical trials on biomarker-oriented postoperative adjuvant chemotherapy for patients with locally advanced GC.

Translocon-associated protein subunit SSR3 determines and predicts susceptibility to paclitaxel in breast cancer and glioblastoma

PURPOSE

Paclitaxel (PTX) is one the most potent and commonly used chemotherapies for breast and pancreatic cancer. Several ongoing clinical trials are investigating means of enhancing delivery of PTX across the blood-brain barrier for glioblastomas (GBMs). Despite the widespread use of PTX for breast cancer, and the initiative to repurpose this drug for gliomas, there are no predictive biomarkers to inform which patients will likely benefit from this therapy.

EXPERIMENTAL DESIGN

To identify predictive biomarkers for susceptibility to PTX, we performed a genome-wide CRISPR knock-out (KO) screen using human glioma cells. The genes whose KO was most enriched in the CRISPR screen underwent further selection based on their correlation with survival in the breast cancer patient cohorts treated with PTX and not in patients treated with other chemotherapies, a finding that was validated on a second independent patient cohort using progression-free survival.

RESULTS

Combination of CRISPR screen results with outcomes from taxane-treated breast cancer patients led to the discovery of endoplasmic reticulum (ER) protein SSR3 as a putative predictive biomarker for PTX. SSR3 protein levels showed positive correlation with susceptibility to PTX in breast cancer cells, glioma cells and in multiple intracranial glioma xenografts models. Knockout of SSR3 turned the cells resistant to PTX while its overexpression sensitized the cells to PTX. Mechanistically, SSR3 confers susceptibility to PTX through regulation of phosphorylation of ER stress sensor IRE1α.

CONCLUSION

Our hypothesis generating study showed SSR3 as a putative biomarker for susceptibility to PTX, warranting its prospective clinical validation.

Tau and stathmin proteins in breast cancer: A potential therapeutic target

Breast cancer is the most common malignant neoplasm among women, responsible for 30% of all malignant tumours, and the second most significant reason of cancer fatality in women. Treatment failure and tumour recurrence are common outcomes of chemotherapy when patients develop multidrug resistance (MDR). New therapeutic methods like molecularly targeted therapeutic interventions need a thorough understanding of malignant tumour's molecular processes. Numerous studies published in the last few years indicate that stathmin and tubulin-associated units (tau) are upregulated in a range of human malignant tumours, suggesting that they may enhance the incidence and progression of malignancies. By promoting cancer cell reproduction, infiltration and generating drug resistance, these proteins aid in the disease's development. Existing information on the expression of tau protein and stathmin in breast cancer, as well as their involvement in treatment methods, is summarized in this literature review.

Dichotomous role of microtubule associated protein tau as a biomarker of response to and a target for increasing efficacy of taxane treatment in cancers of epithelial origin

Cancer is the second leading cause of death worldwide, and the World Health Organization estimates that one in six deaths globally is due to cancer. Chemotherapy is one of the major modalities used to treat advanced cancers and their metastasis. However, the existence of acquired and intrinsic resistance to anti-cancer drugs often diminishes their therapeutic effect. In order to pre-select patients who could benefit the most from these treatments, the efforts of many research groups have been focused on identification of biomarkers of therapy response. Taxanes paclitaxel (Taxol) and docetaxel (Taxotere) have been introduced as chemotherapy for treatment of cancers of ovary in 1992 and breast in 1996, respectively. Since then, clinical use of taxanes has expanded to include lung, prostate, gastric, head and neck, esophageal, pancreatic, and cervical cancers, as well as Kaposi sarcoma. Several independent molecular mechanisms have been shown to support taxane chemoresistance. One such mechanism is dependent on microtubule associated protein tau. Tau binds to the same site on the inner side of the microtubules that is also occupied by paclitaxel or docetaxel, and several studies have demonstrated that low/no tau expression significantly correlated with better response to the taxane treatment, suggesting that levels of tau expression could have a predictive value in pre-selecting patient cohorts that are likely to benefit from the treatment. However, several other studies have found no correlation between tau expression and taxane response, introducing a controversy and precluding its wide use as a predictive biomarker. Based on the knowledge of tau biology accumulated thus far, in this review we attempt to critically analyze the studies that evaluated tau as a biomarker of taxane response. Further, we identify yet unknown aspects of tau biology understanding of which is necessary for improvement of development of tau as a biomarker of response and a target for increasing response to taxane treatment.

Emerging Evidences for an Implication of the Neurodegeneration-Associated Protein TAU in Cancer

Neurodegenerative disorders and cancer may appear unrelated illnesses. Yet, epidemiologic studies indicate an inverse correlation between their respective incidences for specific cancers. Possibly explaining these findings, increasing evidence indicates that common molecular pathways are involved, often in opposite manner, in the pathogenesis of both disease families. Genetic mutations in the MAPT gene encoding for TAU protein cause an inherited form of frontotemporal dementia, a neurodegenerative disorder, but also increase the risk of developing cancer. Assigning TAU at the interface between cancer and neurodegenerative disorders, two major aging-linked disease families, offers a possible clue for the epidemiological observation inversely correlating these human illnesses. In addition, the expression level of TAU is recognized as a prognostic marker for cancer, as well as a modifier of cancer resistance to chemotherapy. Because of its microtubule-binding properties, TAU may interfere with the mechanism of action of taxanes, a class of chemotherapeutic drugs designed to stabilize the microtubule network and impair cell division. Indeed, a low TAU expression is associated to a better response to taxanes. Although TAU main binding partners are microtubules, TAU is able to relocate to subcellular sites devoid of microtubules and is also able to bind to cancer-linked proteins, suggesting a role of TAU in modulating microtubule-independent cellular pathways associated to oncogenesis. This concept is strengthened by experimental evidence linking TAU to P53 signaling, DNA stability and protection, processes that protect against cancer. This review aims at collecting literature data supporting the association between TAU and cancer. We will first summarize the evidence linking neurodegenerative disorders and cancer, then published data supporting a role of TAU as a modifier of the efficacy of chemotherapies and of the oncogenic process. We will finish by addressing from a mechanistic point of view the role of TAU in de-regulating critical cancer pathways, including the interaction of TAU with cancer-associated proteins.

Analysis of Tau Protein Expression in Predicting Pathological Complete Response to Neoadjuvant Chemotherapy in Different Molecular Subtypes of Breast Cancer

PURPOSE

Tau is a microtubule-associated protein that can be found in both normal and abnormal breast cells. Whether the expression of Tau protein can predict the response to neoadjuvant chemotherapy (NACT) is still unclear. In this study, we assessed the role of Tau protein expression in predicting a pathological complete response (pCR) to NACT for different subtypes of breast cancer.

METHODS

Four hundred and sixty-eight eligible patients were retrospectively recruited in our study. The relationship between clinicopathologic factors, including Tau protein expression, and pCR in different subtypes was evaluated using logistic regression analysis. Correlation between Tau and disease-free survival (DFS) and overall survival (OS) was performed using Kaplan-Meier analysis.

RESULTS

The expression of Tau protein was negatively correlated with pCR, especially in triple-negative breast cancer (TNBC). No significant difference was observed in the luminal human epidermal growth factor receptor-2 (HER2)-negative subtype and HER2-positive subtype. Patients with pCR were associated with better DFS and OS (p < 0.05). However, Tau protein expression had no association with either DFS or OS (p > 0.05).

CONCLUSION

Tau protein expression can predict pCR before NACT in TNBC, but there was no correlation between Tau expression and DFS or OS.

Molecular Biology in the Breast Clinics-Current status and future perspectives

Breast cancer is no longer considered a single disease, and with better understanding of cancer biology, its management has evolved over the years, into a complex individualized use of therapeutics based on variable expressions of predictive and prognostic factors. With the advent of molecular and genetic research, the complexity and diversity of breast cancer cells and their ability to survive and develop resistance to treatment strategies became more evident. At the same time, targeted therapies evolved, as specific targets were discovered such as HER2 receptor, and androgen receptor. More recent is the development of immunotherapy which aims at strengthening the host immune system to identify and kill the tumor cells. In breast cancer treatment, use of molecular tests has been a target of controversies, due to their high costs and inaccessibility in limited resource situations. Research in breast cancer is also proceeding at a rapid pace, but it is important to remember that breast cancer continues to be a complex interplay of alterations at molecular and genetic level, with the variability in expressions at protein level leading to difference in behavior and responses to treatment and overall outcome. In the succeeding paragraphs, we will try to review the available evidence in literature and attempt to understand the molecular complexity of breast cancer in order to simplify the art of treating the disease and improving outcomes.

MAPT promoter CpG island hypermethylation is associated with poor prognosis in patients with stage II colorectal cancer

Background

The methylation of microtubule-associated protein tau (MAPT) was first described in patients with Alzheimer’s disease. In this study, we aim to determine if MAPT promoter CpG island is hypermethylated and whether this signature could work as a prognostic marker for patients with stage II colorectal cancer (CRC).

Methods

MAPT methylation level and CpG island methylator phenotype (CIMP) status were examined. The prognostic value of MAPT methylation was analyzed using Cox regression analysis.

Results

Amongst stage II CRC patients (n=107), hypermethylation of MAPT promoter CpG island was seen in 23.4% of them. MAPT methylation was much more frequent in patients with age ≥60 compared to age <60 (P<0.001). MAPT were preferentially methylated among proximal colon tumors or CIMP high tumors (both P<0.001). Five-year overall survival (OS) rates were 57.1% and 79.4% for patients with and without MAPT hypermethylation, respectively, HR=2.33 (95% CI, 1.19–4.57; P=0.014). MAPT hypermethylation remained an important prognostic variable for OS in multivariate analysis with a HR of 2.29 (95% CI, 1.01–5.18; P=0.047).

Conclusion

Our findings suggest that MAPT is frequently methylated and hypermethylation is associated with worse prognosis in patients with stage II CRC.

Aberrant expression of the microtubule-associated protein tau is an independent prognostic feature in prostate cancer

Background

Microtubule-associated protein Tau (MAPT) overexpression has been linked to poor prognosis and decreased response to taxane-based therapies in several cancer types, but its relevance in prostate cancer is unknown.

Methods

In this study, MAPT expression was analyzed by immunohistochemistry on a tissue microarray containing 17,747 prostate cancers.

Results

MAPT was absent in normal prostate epithelial cells but detectable in 1004 (8.2%) of 12,313 interpretable cancers. Its expression was associated with advanced tumor stage, high Gleason grade, positive lymph nodes, and early biochemical recurrence (p < 0.0001 each). For example, MAPT was found in 3.6% of 2072 Gleason ≤3 + 3 cancers but in 14.4% of 704 Gleason ≥4 + 4 cancers. High-level MAPT staining was also linked to TMPRSS2:ERG fusions (p < 0.0001). MAPT staining was seen in 15.2 and 16% of cancers with TMPRSS2:ERG fusion detected by immunohistochemistry and fluorescence in-situ hybridization, but in only 3.5 and 3.9% of cancers without ERG staining or ERG rearrangements. Moreover, an association was found between MAPT expression and PTEN deletions, with 19% MAPT positivity in 948 PTEN deleted cancers but only 7% MAPT positivity in 3895 tumors with normal PTEN copy numbers (p < 0.0001). Multivariate analysis revealed that the prognostic value of MAPT was independent from established parameters. Conventional large section analyses showed intratumoral MAPT heterogeneity in all three analyzed cancers.

Conclusions

The results of our study identify MAPT, as a moderate prognostic marker in prostate cancer, whose clinical impact, however, may be limited due to the rarity and heterogeneity of its expression.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5390-1) contains supplementary material, which is available to authorized users.

Tau regulates the microtubule-dependent migration of glioblastoma cells via the Rho-ROCK signaling pathway

The pathological significance of Tau (encoded by MAPT) in mechanisms driving cell migration in glioblastoma is unclear. By using an shRNA approach to deplete microtubule-stabilizing Tau in U87 cells, we determined its impact on cytoskeletal coordination during migration. We demonstrated here that the motility of these Tau-knockdown cells (shTau cells) was significantly (36%) lower than that of control cells. The shTau cells displayed a slightly changed motility in the presence of nocodazole, which inhibits microtubule formation. Such reduced motility of shTau cells was characterized by a 28% lower number of microtubule bundles at the non-adhesive edges of the tails. In accordance with Tau-stabilized microtubules being required for cell movement, measurements of the front, body and rear section displacements of cells showed inefficient tail retraction in shTau cells. The tail retraction was restored by treatment with Y27632, an inhibitor of Rho-ROCK signaling. Moreover, we clearly identified that shTau cells displayed relocation of the active phosphorylated form of p190-RhoGAP (also known as ARHGAP35), which inhibits Rho-ROCK signaling, and focal adhesion kinase (FAK, also known as PTK2) in cell bodies. In conclusion, our findings indicate that Tau governs the remodeling of microtubule and actin networks for the retraction of the tail of cells, which is necessary for effective migration.

Measurement of molecular biomarkers that predict the tumor response in estrogen receptor-positive breast cancers after dose-dense (biweekly) paclitaxel/carboplatin neoadjuvant chemotherapy

The aim of this study was to determine the predictive value of the clinical and histopathological characteristics of estrogen receptor (ER)-positive patients treated with dose-dense paclitaxel/carboplatin neoadjuvant chemotherapy (NCT). Pathological complete response (pCR) and the change in tumor size between pre- and post-NCT were used to evaluate the tumor response.85 ER-positive breast cancer patients who were treated with dose-dense (biweekly) paclitaxel/carboplatin NCT were analyzed with respect to the expression of progesterone receptor (PgR), Tau, Ki67, human epidermal growth factor receptor 2 (HER2), and Bcl-2 by immunohistochemistry (IHC). These data were used to determine whether these biomarkers could predict the tumor response. A univariate analysis showed that the patients who tested positive for HER2 expression (56.00% vs 11.67%, p<0.01), negative for Tau expression (41.94% vs 14.81%, p=0.005), negative for Bcl-2 expression (46.43% vs 14.04%, p<0.01) and had smaller (≤2 cm) tumors (45.00% vs 18.46%, p=0.02) were associated with higher pCR rates. A multivariate analysis showed that a HER2-positive status (OR: 6.244; 95%CI: 1.734-22.487; p=0.005), Bcl-2-negative status (OR: 0.236; 95%CI: 0.064-0.869; p=0.030) and smaller (≤2 cm) tumor sizes (OR: 0.188; 95%CI: 0.046-0.767; p=0.020) are independent predictors of pCRs. The tumor sizes were significantly reduced in patients with HER2-positive, Tau-negative, Bcl-2-negative and high Ki67 index breast cancer. In conclusion, Bcl-2 negative, HER2-positive and smaller (≤2 cm) tumor sizes are independent predictors of pCR in ER-positive patients treated with dose-dense (biweekly) paclitaxel/carboplatin NCT. This study is registered with ClinicalTrials.gov (NCT0205986).

Prognostic role of excision repair cross complementing-1 and topoisomerase-1 expression in epithelial ovarian cancer

OBJECTIVE

Epithelial ovarian cancer is the most lethal gynecologic cancer worldwide and chemoresistance is one of the major causes of treatment failure. We investigated whether ERCC1, TAU, TOPO2A, TOPO1, P53, and C-MYC expression could be used as predictors for treatment outcomes.

MATERIALS AND METHODS

Immunohistochemical staining was used to examine the expression of these biomarkers in resected tumor specimens from 38 patients treated in our institute. Clinicopathological data including demographics, staging, histological type, treatment response, expression of the biomarkers, and patient outcomes were analyzed.

RESULTS

The median follow-up period was 47.5 months (range, 10-135 months) and the median overall survival was 56.0 months. Patients who did not have expression of ERCC1, and those who had expression of TOPO1 had significantly better overall survival. Cox regression analysis also confirmed that these two biomarkers were significant independent factors predicting survival (ERCC1, hazard ratio 5.51, 95% confidence interval: 2.02-14.00, p = 0.001; TOPO1, hazard ratio 0.22, 95% confidence interval: 0.06-0.77, p = 0.017).

CONCLUSION

We concluded that poor overall survival was significantly associated with positive ERCC1 and negative TOPO1 expression. The results might be the consequence of chemoresistance to platinum and camptothecins, both of which are commonly used regimens in the treatment of epithelial ovarian cancer.

The mitotic tensegrity guardian tau protects mammary epithelia from katanin-like1-induced aneuploidy

The microtubule associated-protein tau has been identified as an effective positive prognostic indicator in breast cancer. To explore the physiological function of tau in early carcinogenesis, endogenous tau was knocked down in primary cultured human mammary epithelial cells. This resulted in chromosome-bridging during anaphase followed by micronucleation, both of which were suppressed by a further katanin-like1 knockdown. We also detected that the exogenously expressed katanin-like1 induction of cellular transformation is prevented by exogenous tau in rat fibroblasts. The mutant katanin-like1 (L123V) identified in breast cancer showed an increase in this transformation capacity as well as microtubule severing activity resistant to tau. The tau knockdown resulted in a loss of the kinetochore fibers on which tau is normally localized. This physical fragility was also observed in isolated tau-knockdown mitotic spindles, supporting the relevance of microtubule damage to the onset of transformation. The karyotyping of tau-knockdown cells showed increased frequency of loss of one X chromosome, further suggesting the involvement of tau in breast tumorigenesis. We propose that tau may contribute to tumor progression by protecting spindle microtubules from excess severing by katanin-like1. We also present data indicating that the microtubule-binding octapeptide NAP is a candidate modifier against the tau deficiency in tumor cells.

Use of Biomarkers to Guide Decisions on Adjuvant Systemic Therapy for Women With Early-Stage Invasive Breast Cancer: American Society of Clinical Oncology Clinical Practice Guideline

PURPOSE

To provide recommendations on appropriate use of breast tumor biomarker assay results to guide decisions on adjuvant systemic therapy for women with early-stage invasive breast cancer.

METHODS

A literature search and prospectively defined study selection sought systematic reviews, meta-analyses, randomized controlled trials, prospective-retrospective studies, and prospective comparative observational studies published from 2006 through 2014. Outcomes of interest included overall survival and disease-free or recurrence-free survival. Expert panel members used informal consensus to develop evidence-based guideline recommendations.

RESULTS

The literature search identified 50 relevant studies. One randomized clinical trial and 18 prospective-retrospective studies were found to have evaluated the clinical utility, as defined by the guideline, of specific biomarkers for guiding decisions on the need for adjuvant systemic therapy. No studies that met guideline criteria for clinical utility were found to guide choice of specific treatments or regimens.

RECOMMENDATIONS

In addition to estrogen and progesterone receptors and human epidermal growth factor receptor 2, the panel found sufficient evidence of clinical utility for the biomarker assays Oncotype DX, EndoPredict, PAM50, Breast Cancer Index, and urokinase plasminogen activator and plasminogen activator inhibitor type 1 in specific subgroups of breast cancer. No biomarker except for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 was found to guide choices of specific treatment regimens. Treatment decisions should also consider disease stage, comorbidities, and patient preferences.

Caveolin-1 Modulates Docetaxel-Induced Cell Death in Breast Cancer Cell Subtypes through Different Mechanisms

Purpose

Caveolin-1 (CAV-1) expression is more associated with basal-like cancers than estrogen receptor- or ErbB-2–expressing breast cancers. However, the biological relevance of different levels of CAV-1 expression according to subtype in the epithelial compartment of breast cancer remains unclear.

Materials and Methods

We investigated whether CAV-1 functions as a tumor suppressor and/or modulator of the cytotoxic activity of docetaxel (DTX) in subtypes of breast cancer using in vitro and xenograft models.

Results

The levels of CAV-1 expression were closely associated with DTX sensitivity in triple-negative breast cancer cells. In addition, CAV-1 significantly inhibited cell proliferation and modulated DTX-induced apoptosis through cell cycle arrest in the G2/M phase. The mechanisms underlying DTX-induced apoptosis differed in breast cancers according to the levels of CAV-1 expression. DTX robustly enhanced Bcl-2 inactivation by CAV-1 in MDA-MB-231 cells, while p53-mediated cell cycle arrest by DTX was more pronounced in CAV-1–low but p53-functional MCF-7 cells. In parallel with the data from breast cancer cell lines, CAV-1–transfected MCF-7 cells showed higher efficacy of DTX treatment in a xenograft model.

Conclusion

We clearly demonstrated cooperative effects between CAV-1 and DTX in mediating apoptosis, suggesting that the levels of CAV-1 expression might be an important indicator for DTX use in breast cancer.

Regulation of human MAPT gene expression

The number of known pathologies involving deregulated Tau expression/metabolism is increasing. Indeed, in addition to tauopathies, which comprise approximately 30 diseases characterized by neuronal aggregation of hyperphosphorylated Tau in brain neurons, this protein has also been associated with various other pathologies such as cancer, inclusion body myositis, and microdeletion/microduplication syndromes, suggesting its possible function in peripheral tissues. In addition to Tau aggregation, Tau deregulation can occur at the expression and/or splicing levels, as has been clearly demonstrated in some of these pathologies. Here, we aim to review current knowledge regarding the regulation of human MAPT gene expression at the DNA and RNA levels to provide a better understanding of its possible deregulation. Several aspects, including repeated motifs, CpG island/methylation, and haplotypes at the DNA level, as well as the key regions involved in mRNA expression and stability and the splicing patterns of different mRNA isoforms at the RNA level, will be discussed.

How Taxol/paclitaxel kills cancer cells

Taxol (generic name paclitaxel) is a microtubule-stabilizing drug that is approved by the Food and Drug Administration for the treatment of ovarian, breast, and lung cancer, as well as Kaposi's sarcoma. It is used off-label to treat gastroesophageal, endometrial, cervical, prostate, and head and neck cancers, in addition to sarcoma, lymphoma, and leukemia. Paclitaxel has long been recognized to induce mitotic arrest, which leads to cell death in a subset of the arrested population. However, recent evidence demonstrates that intratumoral concentrations of paclitaxel are too low to cause mitotic arrest and result in multipolar divisions instead. It is hoped that this insight can now be used to develop a biomarker to identify the ∼50% of patients that will benefit from paclitaxel therapy. Here I discuss the history of paclitaxel and our recently evolved understanding of its mechanism of action.

The active Hsc70/tau complex can be exploited to enhance tau turnover without damaging microtubule dynamics

The pathological accumulation of abnormally hyperphosphorylated and aggregated tau, a neuronal microtubule (MT)-associated protein that functions to maintain MT stability, is implicated in a number of hereditary and sporadic neurodegenerative diseases including frontotemporal dementia and Alzheimer's disease. Targeting tau for the treatment of these diseases is an area of intense interest and toward that end, modulation of cellular molecular chaperones is a potential therapeutic target. In particular, the constitutive Hsp70 isoform, Hsc70, seems highly interconnected with tau, preserving tau protein levels and synergizing with it to assemble MTs. But the relationship between tau and Hsc70, as well as the impact of this interaction in neurons and its therapeutic implications remain unknown. Using a human dominant negative Hsc70 that resembles isoform selective inhibition of this important chaperone, we found for the first time that Hsc70 activity is required to stimulate MT assembly in cells and brain. However, surprisingly, active Hsc70 also requires active tau to regulate MT assembly in vivo, suggesting that tau acts in some ways as a co-chaperone for Hsc70 to coordinate MT assembly. This was despite tau binding to Hsc70 as substrate, as determined biochemically. Moreover, we show that while chronic Hsc70 inhibition damaged MT dynamics, intermittent treatment with a small molecule Hsp70 inhibitor lowered tau in brain tissue without disrupting MT integrity. Thus, in tauopathies, where MT injury would be detrimental to neurons, the unique relationship of tau with the Hsc70 machinery can be exploited to deplete tau levels without damaging MT networks.

Adjuvant chemotherapy for early female breast cancer: a systematic review of the evidence for the 2014 Cancer Care Ontario systemic therapy guideline

BACKGROUND

The Program in Evidence-Based Care (pebc) of Cancer Care Ontario recently created an evidence-based consensus guideline on the systemic treatment of early breast cancer. The evidence for the guideline was compiled using a systematic review to answer the question "What is the optimal systemic therapy for patients with early-stage, operable breast cancer, when patient and disease factors are considered?" The question was addressed in three parts: cytotoxic chemotherapy, endocrine treatment, and human epidermal growth factor receptor 2 (her2)-directed therapy.

METHODS

For the systematic review, the medline and embase databases were searched for the period January 2008 to May 2014. The Standards and Guidelines Evidence directory of cancer guidelines and the Web sites of major oncology guideline organizations were also searched. The basic search terms were "breast cancer" and "systemic therapy" (chemotherapy, endocrine therapy, targeted agents, ovarian suppression), and results were limited to randomized controlled trials (rcts), guidelines, systematic reviews, and meta-analyses.

RESULTS

Several hundred documents that met the inclusion criteria were retrieved. The Early Breast Cancer Trialists' Collaborative Group meta-analyses encompassed many of the rcts found. Several additional studies that met the inclusion criteria were retained, as were other guidelines and systematic reviews. Chemotherapy was reviewed mainly in three classes: anti-metabolite-based regimens (for example, cyclophosphamide-methotrexate-5-fluorouracil), anthracyclines, and taxane-based regimens. In general, single-agent chemotherapy is not recommended for the adjuvant treatment of breast cancer in any patient population. Anthracycline-taxane-based polychemotherapy regimens are, overall, considered superior to earlier-generation regimens and have the most significant impact on patient survival outcomes. Regimens with varying anthracycline and taxane doses and schedules are options; in general, paclitaxel given every 3 weeks is inferior. Evidence does not support the use of bevacizumab in the adjuvant setting; other systemic therapy agents such as metformin and vaccines remain investigatory. Adjuvant bisphosphonates for menopausal women will be discussed in later work.

CONCLUSIONS

The results of this systematic review constitute a comprehensive compilation of the high-level evidence that is the basis for the 2014 pebc guideline on systemic therapy for early breast cancer. Use of cytotoxic chemotherapy is presented here; the results addressing endocrine therapy and her2-targeted treatment, and the final clinical practice recommendations, are published separately in this supplement.

Predictive value of microtubule-associated protein Tau in patients with recurrent and metastatic breast cancer treated with taxane-containing palliative chemotherapy

Tau is a member of microtubule-associated proteins (MAPs) and expressed in normal breast epithelium and breast cancer cells. Tau expression levels in early breast cancer were correlated with the responsiveness of taxane-containing chemotherapy. However, it is unknown whether Tau contributes to breast cancer progression. Herein, Tau expression in recurrent and metastatic breast cancer (RMBC) and its predictive significance in taxane-containing palliative chemotherapy were investigated. Immunohistochemical (IHC) staining was conducted to detect Tau protein expression levels in biopsies from 285 patients with RMBC, and the correlation between Tau expression and sensitivity to taxane was evaluated. One hundred twenty-one (42.46 %, 121/285) patients were Tau positive in their tumor. One hundred ninety-four (68.07 %, 194/285) patients were effective clinical remission, which evaluated with response evaluation criteria in solid tumors (RECIST) criteria. In this group, 141 (85.98 %, 141/194) patients were Tau negative. We further analyzed the correlation between Tau expression and clinicopathological characteristics. Tau expression was positively correlated to estrogen receptor (ER) status. Multivariate logistic regression analysis showed that Tau expression significantly differentiated patients with effective response to treatment (95 % confidence interval (CI): 4.230-13.88, P < 0.01). Tau expression was identified as an independent factor to predict the sensitivity of tumors to taxane-containing palliative chemotherapy in RMBC, suggesting that Tau expression in RMBC may serve as a clinical predictor for taxane-containing palliative chemotherapy.

Classification of subpopulations of cells within human primary brain tumors by single cell gene expression profiling

Brain tumors are heterogeneous with respect to genetic and histological properties of cells within the tumor tissue. To study subpopulations of cells, we developed a protocol for obtaining viable single cells from freshly isolated human brain tissue for single cell gene expression profiling. We evaluated this technique for characterization of cell populations within brain tumor and tumor penumbra. Fresh tumor tissue was obtained from one astrocytoma grade IV and one oligodendroglioma grade III tumor as well as the tumor penumbra of the latter tumor. The tissue was dissociated into individual cells and the expression of 36 genes was assessed by reverse transcription quantitative PCR followed by data analysis. We show that tumor cells from both the astrocytoma grade IV and oligodendroglioma grade III tumor constituted cell subpopulations defined by their gene expression profiles. Some cells from the oligodendroglioma grade III tumor proper shared molecular characteristics with the cells from the penumbra of the same tumor suggesting that a subpopulation of cells within the oligodendroglioma grade III tumor consisted of normal brain cells. We conclude that subpopulations of tumor cells can be identified by using single cell gene expression profiling.

Combination of microtubule associated protein-tau and β-tubulin III predicts chemosensitivity of paclitaxel in patients with advanced gastric cancer

AIM

To investigate the role of microtubule associated protein-tau (MAP-tau) and β-tubulin III (TUBB3) in predicting the chemosensitivity of paclitaxel in patients with advanced gastric cancer (GC).

METHODS

MAP-tau and TUBB3 expressions were detected using immunohistochemistry in 244 advanced GC patients prior to chemotherapy. The associations of MAP-tau and TUBB3 expressions with paclitaxel sensitivity were assessed using in vitro and in vivo xenograft analysis.

RESULTS

A total of 149 patients receiving paclitaxel plus capecitabine (cohort 1) and 95 patients receiving cisplatin plus capecitabine (cohort 2) were included in this study. In cohort 1, the clinical benefit rate (CBR), median progression-free survival (PFS) and overall survival (OS) were found to be significantly higher in patients with low levels of MAP-tau and TUBB3 expressions and were significantly higher than those in patients with high levels of MAP-tau and TUBB3 expressions (CBR: 72.2% versus 35.9%; PFS: 271 versus 102 days; OS: 394 versus 173 days; all P<0.05). This was not observed in cohort 2. In in vitro studies, the sensitivity of paclitaxel in human gastric cancer cells was inversely correlated with the expression levels of MAP-tau and TUBB3, as in in vivo animal xenografts.

CONCLUSIONS

The combination of MAP-tau and TUBB3 was found to predict chemosensitivity to paclitaxel in gastric cancer in vitro and in vivo. This merits further study and may help guide individual therapy.

Assessment of microtubule-associated protein (MAP)-Tau expression as a predictive and prognostic marker in TACT; a trial assessing substitution of sequential docetaxel for FEC as adjuvant chemotherapy for early breast cancer

The TACT trial is the largest study assessing the benefit of taxanes as part of adjuvant therapy for early breast cancer. The goal of this translational study was to clarify the predictive and prognostic value of Tau within the TACT trial. Tissue microarrays (TMA) were available from 3,610 patients. ER, PR, HER2 from the TACT trial and Tau protein expression was determined by immunohistochemistry on duplicate TMAs. Two parallel scoring systems were generated for Tau expression ('dichotomised' vs. 'combined' score). The positivity rate of Tau expression was 50 % in the trial population (n = 2,483). Tau expression correlated positively with ER (p < 0.001) and PR status (p < 0.001); but negatively with histological grade (p < 0.001) and HER2 status (p < 0.001). Analyses with either scoring systems for Tau expression demonstrated no significant interaction between Tau expression and efficacy of docetaxel. Contrary to the hypothesis that taxane benefit would be enriched in Tau negative/low patients, the only groups with a suggestion of a reduced event rate in the taxane group were the HER2-positive, Tau positive subgroups. Tau expression was seen to be a prognostic factor on univariate analysis associated with an improved DFS, independent of the treatment group (p < 0.001). It had no prognostic value in ER-negative tumours and the weak prognostic effect of Tau in ER-positive tumours (p = 0.02) diminished, when considering ER as an ordinal variable. On multivariable analyses, Tau had no prognostic value in either group. In addition, no significant interaction between Tau expression and benefit from docetaxel in patients within the PR-positive and negative subsets was seen. This is now the second large adjuvant study, and the first with quantitative analysis of ER and Tau expression, failing to show an association between Tau and taxane benefit with limited utility as a prognostic marker for Tau in ER-positive early breast cancer patients.

Resistance to first line platinum paclitaxel chemotherapy in serous epithelial ovarian cancer: the prediction value of ERCC1 and Tau expression

In oncology, a rational approach to identify patients who are likely to benefit from therapy, already before initiation of treatment, is urgently required. Excision repair cross-complementation group 1 enzyme (ERCC1) has been proposed as a molecular predictor of clinical resistance to platinum-based chemotherapy. Other data suggest Tau protein expression as a predictor of clinical outcome in cancer patients treated with paclitaxel-based chemotherapy as low tau expression may render microtubules more vulnerable to paclitaxel. Therefore, the combination of ERCC1 and Tau may be a valuable predictor of sensitivity to platinum/paclitaxel treatment. The primary aim of the study was to investigate whether ERCC1 and Tau protein expression correlates with patient outcome in newly diagnosed epithelial ovarian cancer (EOC) patients. Formalin-fixed, paraffin-embedded tissue sections from 227 newly diagnosed EOC patients were used for immunohistochemical staining for ERCC1 and Tau proteins. All patients received standard first-line combination platinum and paclitaxel chemotherapy. The patients were divided in a training set of 84 patients and an independent validation cohort of 143 patients. Neither ERCC1 nor Tau expression was associated with clinical response or platinum resistance in both the training and validation sets. Patients with ERCC1-positive tumors had significantly shortened progression-free and overall survival compared to patients with ERCC1-negative tumors, p<0.00001 and p=0.0006. In multivariate analysis ERCC1 also proved as an independent predictor of PFS and OS with HR of 3.86 and 1.98, respectively but the data could not be confirmed in the validation set. Tau expression was not associated with PFS or OS in this study. ERCC1 and Tau might serve as biomarkers of DNA repair and for paclitaxel sensitivity but the present study could not validate ERCC1 or Tau protein expression in tumors as pre-treatment tools to predict sensitivity to first-line platinum/paclitaxel chemotherapy.

Challenging single- and multi-probesets gene expression signatures of pathological complete response to neoadjuvant chemotherapy in breast cancer: experience of the REMAGUS 02 phase II trial

This study was designed to identify predictive signatures of pathological complete response (pCR) in breast cancer treated by taxane-based regimen, using clinicopathological variables and transcriptomic data (Affymetrix Hgu133 Plus 2.0 devices). The REMAGUS 02 trial (n = 153,training set) and the publicly available M.D. Anderson data set (n = 133, validation set) were used. A re-sampling method was applied. All predictive models were defined using logistic regression and their classification performances were tested through Area Under the Curve (AUC) estimation. A stable set of 42 probesets (31 genes) differentiate pCR or no pCR samples. Single-or 2-probesets signatures, mainly related to ER pathway, were equally predictive of pCR with AUC greater then 0.80. Models including probesets associated with ESR1, MAPT, CA12 or PIGH presented good classification performances. When clinical variables were entered into the model, only CA12 and PIGH, remained informative (p = 0.05 and p = 0.005) showing that a combination of a few genes provided robust and reliable prediction of pCR.

Ixabepilone administered weekly or every three weeks in HER2-negative metastatic breast cancer patients; a randomized non-comparative phase II trial

To explore the activity and safety of two schedules of ixabepilone, as first line chemotherapy, in patients with metastatic breast cancer previously treated with adjuvant chemotherapy, a randomized non-comparative phase II study was conducted. From November 2008 until December 2010, 64 patients were treated with either ixabepilone 40 mg/m(2) every 3 weeks (Group A, 32 patients) or ixabepilone 20 mg/m(2) on days 1, 8 and 15 every 4 weeks (Group B, 32 patients). Overall response rate (the primary end point) was 47% in Group A and 50% in Group B. The most frequent severe adverse events were neutropenia (32% vs. 23%), metabolic disturbances (29% vs. 27%) and sensory neuropathy (12% vs. 27%). Two patients in Group A and 3 in Group B developed febrile neutropenia. After a median follow-up of 22.7 months, median progression-free survival (PFS) was 9 months in Group A and 12 months in Group B. Median survival was 26 months in Group A, whereas it was not reached in Group B. Multiple genetic and molecular markers were examined in tumor and peripheral blood DNA, but none of them was associated with ORR or drug toxicity. Favorable prognostic markers included: the T-variants of ABCB1 SNPs c.2677G/A/T, c.1236C/T and c.3435C/T, as well as high MAPT mRNA and Tau protein expression, which were all associated with the ER/PgR-positive phenotype; absence of TopoIIa; and, an interaction between low TUBB3 mRNA expression and Group B. Upon multivariate analysis, tumor ER-positivity was a favorable (p = 0.0092) and TopoIIa an unfavorable (p = 0.002) prognostic factor for PFS; PgR-positivity was favorable (p = 0.028) for survival. In conclusion, ixabepilone had a manageable safety profile in both the 3-weekly and weekly schedules. A number of markers identified in the present trial appear to deserve further evaluation for their prognostic and/or predictive value in larger multi-arm studies.

TRIAL REGISTRATION

ClinicalTrials.gov NCT 00790894.

FOXA1 expression after neoadjuvant chemotherapy is a prognostic marker in estrogen receptor-positive breast cancer

BACKGROUND

Recent studies have indicated that the response to chemotherapy and the prognostic impact of a pathological complete response (pCR) after neoadjuvant chemotherapy differ among breast cancer subtypes. Predictors of response to chemotherapy and prognostic factors for survival might be different in estrogen receptor (ER)-positive breast cancer.

METHODS

Women with Stage II to III ER-positive HER2-negative breast cancer treated with anthracycline and taxane-containing neoadjuvant chemotherapy between 2003 and 2011 were retrospectively analyzed. Expression of forkhead box A1 (FOXA1), B cell lymphoma 2 (BCL2) and microtubule-associated protein tau (MAPT) as well as ER, progesterone receptor, HER2 and Ki67 was examined by immunohistochemistry in pre- and post-treatment specimens. Factors predictive of response to neoadjuvant chemotherapy and distant disease-free survival were analyzed.

RESULTS

Tumor grade was positively correlated with Ki67 expression. Expression levels of ER were positively correlated with expression levels of HER2, BCL2, FOXA1 and MAPT in pre-treatment tumors. The Ki67 labeling index was the only factor that was significantly associated with clinical response measured by the reduction of tumor volume and pCR. Lymph node status, expression of ER before neoadjuvant chemotherapy and expression of FOXA1 after neoadjuvant chemotherapy were significantly associated with distant disease-free survival, both by univariate and multivariate analyses.

CONCLUSIONS

Patients with ER-positive HER2-negative breast cancer should be selected for neoadjuvant chemotherapy. FOXA1 expression could be a prognostic marker in ER-positive breast cancer.

Tau proteins expressions in advanced breast cancer and its significance in taxane-containing neoadjuvant chemotherapy

Tau is a microtubule-associated protein and expressed in normal breast epithelial cells and breast cancer. Tau expression in breast cancer may be important for chemotherapy optimization. This study is to investigate the expression of Tau in advanced breast cancer and its significance in taxane-containing neoadjuvant chemotherapy. Levels of Tau protein in advanced breast cancer were detected immunohistochemically. The chemotherapeutic efficacy indexes in Tau(-) group, which includes the remission rate, Miller-Payne pathological reactive grade, and pathologic complete response rate, were improved compared with that in Tau(+) group. There was difference in the efficacy indexes among ER+ subgroups but not among ER- patients. In addition, Tau expression was positively correlated (r = 0.32, P < 0.00). In multivariate analysis, when age, clinical stage, postoperative lymph node metastasis, ER, PR, HER2, Ki-67, TP53, or Tau status were included, postoperative lymph node metastasis and Tau-negative status were identified as independent predictors of pathologic complete response. In conclusion, negative Tau protein expression may be an effective predictor for taxane-containing neoadjuvant chemotherapy, especially in ER+ subgroups. Further study on the molecular mechanism and utility of Tau for individualizing adjuvant chemotherapy is warranted.

Tau protein as a potential predictive marker in epithelial ovarian cancer patients treated with paclitaxel/platinum first-line chemotherapy

Background

The aim of the study was to evaluate predictive and prognostic significance of microtubule-associated protein Tau in epithelial ovarian cancer (EOC) patients treated with paclitaxel and platinum-based chemotherapy.

Methods

74 patients with EOC (stage I-IV) who underwent cytoreductive surgery followed by standard paclitaxel/platinum chemotherapy were included in the retrospective analysis. Their formalin-fixed, paraffin-embedded tissue specimens were immunohistochemically stained for Tau protein, using semi-quantitative DAKO test. Tau expression was acknowledged as negative (0 and 1+) or positive (2+ and 3+). The correlation between Tau expression, progression free survival (PFS) and overall survival (OS) was evaluated. Statistical analysis included Kaplan-Meyer estimator, long rank test, Mann Whitney test and Cox proportional hazards model.

Results

25.7% (19/74) and 74.3% (55/74) of the patients were classified as Tau-negative and Tau-positive, respectively. Median PFS was 28.7 months for Tau-negative group and 15.9 months for Tau-positive group (p = 0.0355). In the univariate analysis 3-year OS in Tau-negative and Tau-positive groups was 80.2% and 52.4%, respectively (p = 0.0198). Low expression of protein Tau was associated with better OS, whereas an advanced stage at diagnosis, suboptimal surgery, serous histological type and resistance to first line chemotherapy were each correlated with worse OS (p <0,05). In multivariate analysis only resistance to first line chemotherapy remained significant (HR 22.59; 95% CI, 8.71-58.55; p <0.0001).

Conclusions

Negative tau protein seems to be both good prognostic factor and a predictor of response to paclitaxel/platinum-based chemotherapy in EOC patients.

Predictive and prognostic values of Tau and BubR1 protein in prostate cancer and their relationship to the Gleason score

The aim of this study is to detect the expression levels of spindle assembly checkpoint protein-BubR1 and microtubule-associated protein-Tau in human prostate cancer tissues of different Gleason score, and to test whether there is a relationship between their expression levels and clinicopathologic parameters including response to docetaxel treatment, Gleason score, and overall survival (OS). Moreover, to test whether Tau protein expressed in the cancerous prostate tissue is phosphorylated. Thirty patients who received at least three cycles docetaxel for metastatic castrate-resistant prostate cancer were included into the trial. The patients' formalin-fixed and paraffin-embedded prostate tissue specimens were retrospectively obtained from the pathology department archives of Ege University School of Medicine. The expression status of BubR1 protein was defined by immunohistochemical (IHC) using the anti-BubR1 antibody. The expression status of Tau protein was defined by IHC using the two types of Tau antibodies: anti-Tau-1 antibody (that recognizes Tau only in its dephosphorylated form) and anti-PHF-Tau antibody (that recognizes all isoforms of human Tau proteins independent of its phosphorylation status). The BubR1 and Tau were overexpressed in about 63 and 23 % of the study group, respectively. Tau overexpression was significantly associated with lower Gleason score. There was no significant association between the expression levels of BubR1 and Tau proteins, and docetaxel response. Reduced BubR1 expression was strongly associated with longer survival (P = 0.008), whereas Tau expression status did not effect survival. Moreover, the Tau expression of cancerous prostate tissue was highly dephosphorylated. In this clinicopathological study, our findings did not confirm the preclinical observations that low BubR1 and Tau expression confer selective sensitivity to microtubulisin drugs. Our data imply that reduced BubR1 expression was a predictor for longer OS, and the possibility that high Tau expression may be involved in better prognosis due to its relationship to the Gleason score. Furthermore, our data suggest that both Tau and BubR1 may be a promising prognostic marker rather than predictive marker in patients with prostate cancer.

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.

PAM50 proliferation score as a predictor of weekly paclitaxel benefit in breast cancer

To identify a group of patients who might benefit from the addition of weekly paclitaxel to conventional anthracycline-containing chemotherapy as adjuvant therapy of node-positive operable breast cancer. The predictive value of PAM50 subtypes and the 11-gene proliferation score contained within the PAM50 assay were evaluated in 820 patients from the GEICAM/9906 randomized phase III trial comparing adjuvant FEC to FEC followed by weekly paclitaxel (FEC-P). Multivariable Cox regression analyses of the secondary endpoint of overall survival (OS) were performed to determine the significance of the interaction between treatment and the (1) PAM50 subtypes, (2) PAM50 proliferation score, and (3) clinical and pathological variables. Similar OS analyses were performed in 222 patients treated with weekly paclitaxel versus paclitaxel every 3 weeks in the CALGB/9342 and 9840 metastatic clinical trials. In GEICAM/9906, with a median follow up of 8.7 years, OS of the FEC-P arm was significantly superior compared to the FEC arm (unadjusted HR = 0.693, p = 0.013). A benefit from paclitaxel was only observed in the group of patients with a low PAM50 proliferation score (unadjusted HR = 0.23, p < 0.001; and interaction test, p = 0.006). No significant interactions between treatment and the PAM50 subtypes or the various clinical–pathological variables, including Ki-67 and histologic grade, were identified. Finally, similar OS results were obtained in the CALGB data set, although the interaction test did not reach statistical significance (p = 0.109). The PAM50 proliferation score identifies a subset of patients with a low proliferation status that may derive a larger benefit from weekly paclitaxel.

Lysine post-translational modifications and the cytoskeleton

PTMs (post-translational modifications) of lysine residues have proven to be major regulators of gene expression, protein-protein interactions, and protein processing and degradation. This is of particular importance in regulating the cytoskeleton, an enormously complex system of proteins responsible for cell motility, intracellular trafficking, and maintenance of cell form and structure. The cytoskeleton is present in all cells, including eukaryotes and prokaryotes, and comprises structures such as flagella, cilia and lamellipodia which play critical roles in intracellular transport and cellular division. Cytoskeletal regulation relies on numerous multi-component assemblies. In this chapter, we focus on the regulation of the cytoskeleton by means of PTMs of lysine residues on the cytoskeletal subunits and their accessory proteins. We specifically address the three main classes of cytoskeletal proteins in eukaryotes that polymerize into filaments, including microfilaments (actin filaments), intermediate filaments and microtubules. We discuss the identification and biological importance of lysine acetylation, a regulator of all three filament types. We also review additional lysine modifications, such as ubiquitination and SUMOylation, and their role in protein regulation and processing.

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.

Biomarkers predicting clinical benefit: fact or fiction?

Preoperative therapy is increasingly used in operable disease to improve the chance for breast-conservative surgery. Moreover, this strategy allows for a better definition of patient prognosis. Independently from stage at diagnosis and breast cancer subtype, the achievement of a pathological complete response (pCR) is a surrogate marker for long-term outcome. The likelihood of pCR depends on tumor biology, being poorly differentiated tumors with ductal histology, absence of hormone receptors, and high proliferation rate those with a higher chance of achieving a CR. However, pCR is a late efficacy parameter that can be evaluated at the end of the preoperative treatment; moreover, a pCR is achieved in a minority of patients and is not an appropriate efficacy measure for neoadjuvant endocrine therapy. The predictive role of tumor biomarkers such as p53, microtubule-associated tau protein, and poly (ADP-ribose) polymerase will be reviewed along with potential markers of early treatment effect.

HER2 and TOP2A in high-risk early breast cancer patients treated with adjuvant epirubicin-based dose-dense sequential chemotherapy

Background

HER2 and TOP2A parameters (gene status, mRNA and protein expression) have individually been associated with the outcome of patients treated with anthracyclines. The aim of this study was to comprehensively evaluate the prognostic/predictive significance of the above parameters in early, high-risk breast cancer patients treated with epirubicin-based, dose-dense sequential adjuvant chemotherapy.

Methods

In a series of 352 breast carcinoma tissues from patients that had been post-operatively treated with epirubicin-CMF with or without paclitaxel, we assessed HER2 and TOP2A gene status (chromogenic in situ hybridization), mRNA expression (quantitative reverse transcription PCR), as well as HER2 and TopoIIa protein expression (immunohistochemistry).

Results

HER2 and TOP2A amplification did not share the same effects on their downstream molecules, with consistent patterns observed in HER2 mRNA and protein expression according to HER2 amplification (all parameters strongly inter-related, p values < 0.001), but inconsistent patterns in the case of TOP2A. TOP2A gene amplification (7% of all cases) was not related to TOP2A mRNA and TopoIIa protein expression, while TOP2A mRNA and TopoIIa protein were strongly related to each other (p < 0.001). Hence, TOP2A amplified tumors did not correspond to tumors with high TOP2A mRNA or TopoIIa protein expression, while the latter were characterized by high Ki67 scores (p = 0.003 and p < 0.001, respectively). Multivariate analysis adjusted for nodal involvement, hormone receptor status, Ki67 score and HER2/TOP2A parameters revealed HER2/TOP2A co-amplification (21.2% of HER2 amplified tumors) as an independent favorable prognostic factor for DFS (HR = 0.13, 95% CI: 0.02-0.96, p = 0.046); in contrast, increased HER2/TOP2A mRNA co-expression was identified as an independent adverse prognostic factor for both DFS (HR = 2.41, 95% CI: 1.31-4.42, p = 0.005) and OS (HR = 2.83, 95% CI: 1.42-5.63, p = 0.003), while high TOP2A mRNA expression was an independent adverse prognostic factor for OS (HR = 2.06, 95% CI: 1.23-3.46, p = 0.006). None of the parameters tested was associated with response to paclitaxel.

Conclusions

This study confirms the favorable prognostic value of HER2/TOP2A co-amplification and the adverse prognostic value of high TOP2A mRNA expression extending it to the adjuvant treatment setting in early high-risk breast cancer. The strong adverse prognostic impact of high HER2/TOP2A mRNA co-expression needs further validation in studies designed to evaluate markers predictive for anthracyclines.

Trial registration

Australian New Zealand Clinical Trials Registry ACTRN12611000506998.

TLE3 expression is associated with sensitivity to taxane treatment in ovarian carcinoma

BACKGROUND

We have previously shown that transducin-like enhancer of split 3 (TLE3) is associated with outcome specifically in patients with taxane-treated breast cancer and not in patients treated with anthracycline-based regimens without a taxane. The purpose of this study was to assess the association between TLE3 expression and recurrence in patients with ovarian carcinoma treated with a taxane containing regimen as opposed to those treated with a platinum-based agent alone.

METHODS

We carried out immunohistochemical staining of TLE3 in two series of ovarian cancer specimens from the University of Alabama at Birmingham, Birmingham, AL and the Royal Hospital for Women, Sydney, Australia. Local and distant recurrences within the first five years of follow-up were analyzed using Kaplan-Meier, Cox proportional hazard, and multivariate analysis to assess an association between TLE3 expression and response to therapy.

RESULTS

TLE3 was expressed in approximately 30% of tumors and expression was associated with a favorable outcome only in patients who had received taxane as part of their treatment regimen (n = 173, HR = 0.62, P = 0.012; P(interaction) = 0.024). Further analysis revealed that the predictive association between TLE3 expression and outcome was strongest in patients with nonserous histology.

CONCLUSION

High TLE3 expression predicts a favorable response to taxane containing chemotherapy regimens in ovarian carcinoma.

IMPACT

Our findings warrant an independent evaluation of TLE3 as a potential therapeutic response marker for taxane-based chemotherapy in ovarian cancer.

Evaluation of prognostic and predictive value of microtubule associated protein tau in two independent cohorts

Introduction

Microtubule associated proteins (MAPs) endogenously regulate microtubule stabilization and have been reported as prognostic and predictive markers for taxane response. The microtubule stabilizer, MAP-tau, has shown conflicting results. We quantitatively assessed MAP-tau expression in two independent breast cancer cohorts to determine prognostic and predictive value of this biomarker.

Methods

MAP-tau expression was evaluated in the retrospective Yale University breast cancer cohort (n = 651) using tissue microarrays and also in the TAX 307 cohort, a clinical trial randomized for TAC versus FAC chemotherapy (n = 140), using conventional whole tissue sections. Expression was measured using the AQUA method for quantitative immunofluorescence. Scores were correlated with clinicopathologic variables, survival, and response to therapy.

Results

Assessment of the Yale cohort using Cox univariate analysis indicated an improved overall survival (OS) in tumors with a positive correlation between high MAP-tau expression and overall survival (OS) (HR = 0.691, 95% CI = 0.489-0.974; P = 0.004). Kaplan Meier analysis showed 10-year survival for 65% of patients with high MAP-tau expression compared to 52% with low expression (P = .006). In TAX 307, high expression was associated with significantly longer median time to tumor progression (TTP) regardless of treatment arm (33.0 versus 23.4 months, P = 0.010) with mean TTP of 31.2 months. Response rates did not differ by MAP-tau expression (P = 0.518) or by treatment arm (P = 0.584).

Conclusions

Quantitative measurement of MAP-tau expression has prognostic value in both cohorts, with high expression associated with longer TTP and OS. Differences by treatment arm or response rate in low versus high MAP-tau groups were not observed, indicating that MAP-tau is not associated with response to taxanes and is not a useful predictive marker for taxane-based chemotherapy.

Src family kinases and paclitaxel sensitivity

Src-family Kinases (SFKs) participate in the regulation of proliferation, differentiation, apoptosis, autophagy, adhesion, migration, invasion and angiogenesis in normal and cancer cells. Abnormal expression of SFKs has been documented in cancers that arise in breast, colon, ovary, melanocyte, gastric mucosa, head and neck, pancreas, lung, and brain. Targeting SFKs in cancer cells has been shown to be a promising therapeutic strategy in solid tumors, particularly in ovarian, colon and breast cancers. Paclitaxel is one of most widely used chemotherapeutic agents for the management of ovarian, breast, lung and head/neck cancers. As a microtubule-stabilizing agent, paclitaxel possesses both mitosis-dependent and mitosis-independent activities against cancer cells. A variety of mechanisms such as deregulation of P-glycoprotein, alteration of tubulin isotypes, alteration of microtubule-regulatory proteins, deregulation of apoptotic signaling pathways, mutation of tubulins and overexpression of copper transporters have been implicated in the development of primary or secondary resistance to paclitaxel. By affecting cancer cell survival, proliferation, autophagy, microtubule stability, motility, and/or angiogenesis, SFKs interact with mechanisms that regulate paclitaxel sensitivity. Inhibition of SFKs can potentiate the anti-tumor activity of paclitaxel by enhancing apoptosis, autophagy and microtubule stability. Based on pre-clinical observations, administration of SFK inhibitors in combination with paclitaxel could improve treatment for ovarian, breast, lung and head/neck cancers. Identification and validation of predictive biomarkers could also permit personalization of the therapy.

Gene expression profiling of breast tumor cell lines to predict for therapeutic response to microtubule-stabilizing agents

Microtubule-targeting agents, including taxanes (Tax) and ixabepilone (Ixa), are important components of modern breast cancer chemotherapy regimens, but no molecular parameter is currently available that can predict for their efficiency. We sought to develop pharmacogenomic predictors of Tax- and Ixa-response from a large panel of human breast tumor cell lines (BTCL), then to evaluate their performance in clinical samples. Thirty-two BTCL, representative of the molecular diversity of breast cancers (BC), were treated in vitro with Tax (paclitaxel (Pac), docetaxel (Doc)), and ixabepilone (Ixa), then classified as drug-sensitive or resistant according to their 50% inhibitory concentrations (IC50s). Baseline gene expression data were obtained using Affymetrix U133 Plus 2.0 human oligonucleotide microarrays. Gene expression set (GES) predictors of response to taxanes were derived, then tested for validation internally and in publicly available gene expression datasets. In vitro IC50s of Pac and Doc were almost identical, whereas some Tax-resistant BTCL retained sensitivity to Ixa. GES predictors for Tax-sensitivity (333 genes) and Ixa-sensitivity (79 genes) were defined. They displayed a limited number of overlapping genes. Both were validated by leave-n-out cross-validation (n = 4; for overall accuracy (OA), P = 0.028 for Tax, and P = 0.0005 for Ixa). The GES predictor of Tax-sensitivity was tested on publicly available external datasets and significantly predicted Pac-sensitivity in 16 BTCL (P = 0.04 for OA), and pathological complete response to Pac-based neoadjuvant chemotherapy in BC patients (P = 0.0045 for OA). Applying Tax and Ixa-GES to a dataset of clinically annotated early BC patients identified subsets of tumors with potentially distinct phenotypes of drug sensitivity: predicted Ixa-sensitive/Tax-resistant BC were significantly (P < 0.05, Fischer's exact test) more frequently ER/PR-positive, Ki67-negative, and luminal subtype than predicted Ixa-resistant/Tax-sensitive BC. Genomic predictors for Tax- and Ixa-sensitivity can be derived from BTCL and may be helpful for better selecting cytotoxic treatment in BC patients.

The role of Tau protein in resistance to paclitaxel

Resistance to taxanes, related to limited efficacy of systemic therapy in cancer patients, is multifactorial. Among mechanisms of resistance to taxanes, those related to microtubule-associated proteins (MAP), including protein Tau, are of great importance. Protein Tau (50–64 kD) binds to beta-tubulin in the same place as paclitaxel. In preclinical studies, low expression of Tau in cancer cells was associated with increased sensitivity to paclitaxel. High expression of Tau protein in ER-positive breast cancers indicates resistance to taxane-containing chemotherapy and sensitivity to hormonal treatment. This article reviews current knowledge on predictive value of protein Tau in response to taxanes. Better understanding of its role may facilitate patients selection to this sort of treatment and lead to treatment optimization.

Chemotherapy: updates and new perspectives

Treatment options for patients with breast cancer have progressively improved over the past 40 years, from an era of no chemotherapy to the introduction of taxanes, hormonal therapy, and biologic therapy. These advances have resulted in substantial, 15%-20% improvements in clinical outcomes. However, progress has yet to be made to improve the prognosis in many breast cancer patients, and research is currently under way to test new tools, or new applications of older tools, to advance breast cancer management. Chemotherapy clearly remains a cornerstone of adjuvant breast cancer treatment, because breast cancer can be very sensitive to the currently available agents. Meanwhile, the era of a one-size-fits-all approach to breast cancer management is over, and the maximum potential of chemotherapy should now be reached by targeting specific populations. Effective biomarkers are therefore needed to optimize chemotherapy, define more selective populations, and clearly tailor treatment. This paper discusses recent data, including new trials that are more fully incorporating current knowledge with respect to molecular markers and the underlying biology of breast cancer.