Class III β-tubulin (TUBB3): more than a biomarker in solid tumors?

Targeting Heme Oxygenase 2 (HO2) with TiNIR, a Theragnostic Approach for Managing Metastatic Non-Small Cell Lung Cancer

Despite notable advancements in cancer therapeutics, metastasis remains a primary obstacle impeding a successful prognosis. Our prior study has identified heme oxygenase 2 (HO2) as a promising therapeutic biomarker for the aggressive subsets within tumor. This study aims to systematically evaluate HO2 as a therapeutic target of cancer, with a specific emphasis on its efficacy in addressing cancer metastasis. Through targeted inhibition of HO2 by TiNIR (tumor-initiating cell probe with near infrared), we observed a marked increase in reactive oxygen species. This, in turn, orchestrated the modulation of AKT and cJUN activation, culminating in a substantial attenuation of both proliferation and migration within a metastatic cancer cell model. Furthermore, in a mouse model, clear inhibition of cancer metastasis was unequivocally demonstrated with an HO2 inhibitor administration. These findings underscore the therapeutic promise of targeting HO2 as a strategic intervention to impede cancer metastasis, enhancing the effectiveness of cancer treatments.

Targeted therapies in bladder cancer: signaling pathways, applications, and challenges

Bladder cancer (BC) is one of the most prevalent malignancies in men. Understanding molecular characteristics via studying signaling pathways has made tremendous breakthroughs in BC therapies. Thus, targeted therapies including immune checkpoint inhibitors (ICIs), antibody-drug conjugates (ADCs), and tyrosine kinase inhibitor (TKI) have markedly improved advanced BC outcomes over the last few years. However, the considerable patients still progress after a period of treatment with current therapeutic regimens. Therefore, it is crucial to guide future drug development to improve BC survival, based on the molecular characteristics of BC and clinical outcomes of existing drugs. In this perspective, we summarize the applications and benefits of these targeted drugs and highlight our understanding of mechanisms of low response rates and immune escape of ICIs, ADCs toxicity, and TKI resistance. We also discuss potential solutions to these problems. In addition, we underscore the future drug development of targeting metabolic reprogramming and cancer stem cells (CSCs) with a deep understanding of their signaling pathways features. We expect that finding biomarkers, developing novo drugs and designing clinical trials with precisely selected patients and rationalized drugs will dramatically improve the quality of life and survival of patients with advanced BC.

Exosomal TUBB3 mRNA expression of metastatic castration-resistant prostate cancer patients: Association with patient outcome under abiraterone

Background

To use ddPCR to quantify plasma exosomal class III β‐tubulin (βIII‐tubulin, TUBB3, encoded by the TUBB3 gene) mRNA expression in metastatic castration‐resistant prostate cancer (mCRPC) patients, and study the association of this expression with abiraterone efficacy.

Methods

Blood samples were prospectively collected from 52 mCRPC patients using abiraterone as first‐line therapy to measure plasma exosomal TUBB3 mRNA expression value before the initiation of abiraterone. Study endpoints were PSA response rate, PSA‐progression‐free survival (PSA‐PFS), and overall survival (OS, from CRPC to death).

Results

Patients with positive exosomal TUBB3 expression showed shorter PSA‐PFS (negative TUBB3 vs. positive TUBB3: 11.0 vs. 7.9 months; p = 0.014). Further analysis demonstrated that patients with strongly positive exosomal TUBB3 (>20 copies/20 µl) was associated with even shorter PSA‐PFS (negative TUBB3 vs. positive TUBB3 [<20 copies/20 µl] vs. strongly positive TUBB3 [>20 copies/20 µl]: 11.0 vs. 8.3 vs. 3.6 months, p = 0.005). In multivariate analyzes, TUBB3 (+) (HR: 2.114, p = 0.033) and ECOG score >2 (HR: 3.039, p = 0.006) were independent prognosticators of poor PSA‐PFS. PSA response and OS did not present significant differences.

Conclusion

The exosomal TUBB3 mRNA expression level is associated with poor PSA‐PFS of abiraterone in mCRPC patients. The detection of exosomal TUBB3 can be valuable in their management.

Energy Metabolic Plasticity of Colorectal Cancer Cells as a Determinant of Tumor Growth and Metastasis

Metabolic plasticity is the ability of the cell to adjust its metabolism to changes in environmental conditions. Increased metabolic plasticity is a defining characteristic of cancer cells, which gives them the advantage of survival and a higher proliferative capacity. Here we review some functional features of metabolic plasticity of colorectal cancer cells (CRC). Metabolic plasticity is characterized by changes in adenine nucleotide transport across the outer mitochondrial membrane. Voltage-dependent anion channel (VDAC) is the main protein involved in the transport of adenine nucleotides, and its regulation is impaired in CRC cells. Apparent affinity for ADP is a functional parameter that characterizes VDAC permeability and provides an integrated assessment of cell metabolic state. VDAC permeability can be adjusted via its interactions with other proteins, such as hexokinase and tubulin. Also, the redox conditions inside a cancer cell may alter VDAC function, resulting in enhanced metabolic plasticity. In addition, a cancer cell shows reprogrammed energy transfer circuits such as adenylate kinase (AK) and creatine kinase (CK) pathway. Knowledge of the mechanism of metabolic plasticity will improve our understanding of colorectal carcinogenesis.

Y box binding protein 1 inhibition as a targeted therapy for ovarian cancer

Y box binding protein 1 (YB-1) is a multifunctional protein associated with tumor progression and the emergence of treatment resistance (TR). Here, we report an azopodophyllotoxin small molecule, SU056, that potently inhibits tumor growth and progression via YB-1 inhibition. This YB-1 inhibitor inhibits cell proliferation, resistance to apoptosis in ovarian cancer (OC) cells, and arrests in the G1 phase. Inhibitor treatment leads to enrichment of proteins associated with apoptosis and RNA degradation pathways while downregulating spliceosome pathway. In vivo, SU056 independently restrains OC progression and exerts a synergistic effect with paclitaxel to further reduce disease progression with no observable liver toxicity. Moreover, in vitro mechanistic studies showed delayed disease progression via inhibition of drug efflux and multidrug resistance 1, and significantly lower neurotoxicity as compared with etoposide. These data suggest that YB-1 inhibition may be an effective strategy to reduce OC progression, antagonize TR, and decrease patient mortality.

Association of high TUBB3 with resistance to adjuvant docetaxel-based chemotherapy in gastric cancer: translational study of ITACA-S

BACKGROUND

No predictive markers for chemotherapy activity have been validated in gastric cancer (GC). The potential value of class III β-tubulin (TUBB3) as biomarker for prognosis and resistance to taxane-based therapy was reported.

METHODS

We analyzed GC samples of patients enrolled in the Intergroup Trial of Adjuvant Chemotherapy in Adenocarcinoma of the Stomach (ITACA-S), a randomized adjuvant study comparing 5-fluorouracil/leucovorin (5-FU/LV) and docetaxel-based sequential chemotherapy. TUBB3 was quantitated by selected reaction monitoring mass spectrometry and patients were stratified using a threshold of 750 attomoles per microgram (amol/µg). Cox proportional modeling and Kaplan-Meier survival analysis were used to assess the impact of TUBB3 expression on overall survival (OS) and disease-free survival.

RESULTS

Patients with TUBB3 protein levels >750 and <750 amol/µg were 21.9% and 78.1%, respectively, and were well-balanced between treatment arms. TUBB3 protein levels were not prognostic. Whereas no survival differences according to the 2 arms were observed in the subgroup with low TUBB3 expression (5-year OS 47% vs 40%; p = 0.44), patients with high TUBB3 had a clinically meaningful poorer OS when receiving docetaxel-based versus 5-FU/LV chemotherapy (5-year OS 31% vs 54%; p = 0.09), with a statistically significant interaction between TUBB3 and treatment (p = 0.049).

CONCLUSIONS

The quantification of TUBB3 might be considered as a negative predictive biomarker of benefit from taxane-based therapy in GC. Studies are needed to evaluate its role in the neoadjuvant setting.

Tubulin βII and βIII Isoforms as the Regulators of VDAC Channel Permeability in Health and Disease

In recent decades, there have been several models describing the relationships between the cytoskeleton and the bioenergetic function of the cell. The main player in these models is the voltage-dependent anion channel (VDAC), located in the mitochondrial outer membrane. Most metabolites including respiratory substrates, ADP, and Pi enter mitochondria only through VDAC. At the same time, high-energy phosphates are channeled out and directed to cellular energy transfer networks. Regulation of these energy fluxes is controlled by β-tubulin, bound to VDAC. It is also thought that β-tubulin‒VDAC interaction modulates cellular energy metabolism in cancer, e.g., switching from oxidative phosphorylation to glycolysis. In this review we focus on the described roles of unpolymerized αβ-tubulin heterodimers in regulating VDAC permeability for adenine nucleotides and cellular bioenergetics. We introduce the Mitochondrial Interactosome model and the function of the βII-tubulin subunit in this model in muscle cells and brain synaptosomes, and also consider the role of βIII-tubulin in cancer cells.

Multiplicity of acquired cross-resistance in paclitaxel-resistant cancer cells is associated with feedback control of TUBB3 via FOXO3a-mediated ABCB1 regulation

Acquired drug resistance is a primary obstacle for effective cancer therapy. The correlation of point mutations in class III β-tubulin (TUBB3) and the prominent overexpression of ATP-binding cassette P-glycoprotein (ABCB1), a multidrug resistance gene, have been protruding mechanisms of resistance to microtubule disruptors such as paclitaxel (PTX) for many cancers. However, the precise underlying mechanism of the rapid onset of cross-resistance to an array of structurally and functionally unrelated drugs in PTX-resistant cancers has been poorly understood. We determined that our established PTX-resistant cancer cells display ABCB1/ABCC1-associated cross-resistance to chemically different drugs such as 5-fluorouracil, docetaxel, and cisplatin. We found that feedback activation of TUBB3 can be triggered through the FOXO3a-dependent regulation of ABCB1, which resulted in the accentuation of induced PTX resistance and encouraged multiplicity in acquired cross-resistance. FOXO3a-directed regulation of P-glycoprotein (P-gp) function suggests that control of ABCB1 involves methylation-dependent activation. Consistently, transcriptional overexpression or downregulation of FOXO3a directs inhibitor-controlled protease-degradation of TUBB3. The functional PI3K/Akt signaling is tightly responsive to FOXO3a activation alongside doxorubicin treatment, which directs FOXO3a arginine hypermethylation. In addition, we found that secretome factors from PTX-resistant cancer cells with acquired cross-resistance support a P-gp-dependent association in multidrug resistance (MDR) development, which assisted the FOXO3a-mediated control of TUBB3 feedback. The direct silencing of TUBB3 reverses induced multiple cross-resistance, reduces drug-resistant tumor mass, and suppresses the impaired microtubule stability status of PTX-resistant cells with transient cross-resistance. These findings highlight the control of the TUBB3 response to ABCB1 genetic suppressors as a mechanism to reverse the profuse development of multidrug resistance in cancer.

High-level βIII-tubulin overexpression occurs in most head and neck cancers but is unrelated to clinical outcome

BACKGROUND

βIII-tubulin (TUBB3) is an isotype of microtubules, which are involved in crucial cellular roles including maintenance of cell shape, intracellular transport, and mitosis. Overexpression of TUBB3 was found to be associated with poor prognosis and resistance to tubulin-binding drugs and in several solid tumors including head and neck squamous cell carcinomas (HNSCC). Considering the potential high importance of a prognostic biomarker in these cancers, this study aimed to investigate the clinical relevance of immunohistochemical TUBB3 expression in HNSCC.

METHODS

Tissue microarray (TMA) sections containing samples from 667 cancers of oral cavity, oro- and hypopharynx, and larynx for which follow-up data were available were analyzed for TUBB3 expression by immunohistochemistry.

RESULTS

Over 90% of our analyzed cancers showed unequivocal cytoplasmic TUBB3 expression. Staining was considered weak in 69 (15.5%), moderate in 149 (33.5%), and strong in 188 (42.2%) of cancers. The frequent TUBB3 overexpression showed no significant correlation with pathological grading, tumor stage, nodal status, or surgical margin and had no impact on patient outcomes.

CONCLUSION

Despite lacking prognostic utility in HNSCC, the remarkable high prevalence of TUBB3 expression in HNSCC emphasizes its putative relevance as a target for future drugs targeting TUBB3.

Site-specific gene expression profiling as a novel strategy for unravelling keloid disease pathobiology

Keloid disease (KD) is a fibroproliferative cutaneous tumour characterised by heterogeneity, excess collagen deposition and aggressive local invasion. Lack of a validated animal model and resistance to a multitude of current therapies has resulted in unsatisfactory clinical outcomes of KD management. In order to address KD from a new perspective, we applied for the first time a site-specific in situ microdissection and gene expression profiling approach, through combined laser capture microdissection and transcriptomic array. The aim here was to analyse the utility of this approach compared with established methods of investigation, including whole tissue biopsy and monolayer cell culture techniques. This study was designed to approach KD from a hypothesis-free and compartment-specific angle, using state-of-the-art microdissection and gene expression profiling technology. We sought to characterise expression differences between specific keloid lesional sites and elucidate potential contributions of significantly dysregulated genes to mechanisms underlying keloid pathobiology, thus informing future explorative research into KD. Here, we highlight the advantages of our in situ microdissection strategy in generating expression data with improved sensitivity and accuracy over traditional methods. This methodological approach supports an active role for the epidermis in the pathogenesis of KD through identification of genes and upstream regulators implicated in epithelial-mesenchymal transition, inflammation and immune modulation. We describe dermal expression patterns crucial to collagen deposition that are associated with TGFβ-mediated signalling, which have not previously been examined in KD. Additionally, this study supports the previously proposed presence of a cancer-like stem cell population in KD and explores the possible contribution of gene dysregulation to the resistance of KD to conventional therapy. Through this innovative in situ microdissection gene profiling approach, we provide better-defined gene signatures of distinct KD regions, thereby addressing KD heterogeneity, facilitating differential diagnosis with other cutaneous fibroses via transcriptional fingerprinting, and highlighting key areas for future KD research.

Secreted primary human malignant mesothelioma exosome signature reflects oncogenic cargo

Malignant mesothelioma (MM) is a highly-aggressive heterogeneous malignancy, typically diagnosed at advanced stage. An important area of mesothelioma biology and progression is understanding intercellular communication and the contribution of the secretome. Exosomes are secreted extracellular vesicles shown to shuttle cellular cargo and direct intercellular communication in the tumour microenvironment, facilitate immunoregulation and metastasis. In this study, quantitative proteomics was used to investigate MM-derived exosomes from distinct human models and identify select cargo protein networks associated with angiogenesis, metastasis, and immunoregulation. Utilising bioinformatics pathway/network analyses, and correlation with previous studies on tumour exosomes, we defined a select mesothelioma exosomal signature (mEXOS, 570 proteins) enriched in tumour antigens and various cancer-specific signalling (HPGD/ENO1/OSMR) and secreted modulators (FN1/ITLN1/MAMDC2/PDGFD/GBP1). Notably, such circulating cargo offers unique insights into mesothelioma progression and tumour microenvironment reprogramming. Functionally, we demonstrate that oncogenic exosomes facilitate the migratory capacity of fibroblast/endothelial cells, supporting the systematic model of MM progression associated with vascular remodelling and angiogenesis. We provide biophysical and proteomic characterisation of exosomes, define a unique oncogenic signature (mEXOS), and demonstrate the regulatory capacity of exosomes in cell migration/tube formation assays. These findings contribute to understanding tumour-stromal crosstalk in the context of MM, and potential new diagnostic and therapeutic extracellular targets.

Expression of BRCA1, a factor closely associated with relapse-free survival, in patients who underwent neoadjuvant chemotherapy with docetaxel, cisplatin, and fluorouracil for squamous cell carcinoma of the esophagus

PURPOSE

The aim of this study was to identify the biomarkers associated with chemotherapeutic efficacy and long-term survival for patients with advanced squamous cell carcinoma of the esophagus (SCCE) who had received neoadjuvant chemotherapy with docetaxel and cisplatin plus 5-fluorouracil (NAC-DCF).

METHODS

This study included 45 patients with advanced SCCE who received NAC-DCF between 2008 and 2012. The NAC-DCF was conducted as a phase II study (UMIN000007408). The expressions of excision repair cross-complementing-1 (ERCC1), class III beta-tubulin, breast cancer susceptibility gene I (BRCA1), and thymidylate synthase were investigated simultaneously in the pre-treatment endoscopic tumor biopsy samples.

RESULTS

A multivariate logistic regression analysis indicated that pathological responses were significantly associated with tumors with low ERCC1 expression (P = 0.016) and with tumors with high BRCA1 expression (P = 0.030). The multivariate Cox proportional hazard model analysis for relapse-free survival revealed high BRCA1 expression (P = 0.031, hazards ratio 4.39) as the factor associated with survival.

CONCLUSIONS

Low ERCC1 expression and high BRCA1 expression in patients with SCCE were associative biomarkers for chemotherapeutic efficacy. High BRCA1 expression was considered the factor associated with survival. These findings may be helpful for tailoring chemotherapy.

Mitochondrial Dysfunction in Gliomas: Pharmacotherapeutic Potential of Natural Compounds

Gliomas are the most common primary brain tumors either benign or malignant originating from the glial tissue. Glioblastoma multiforme (GBM) is the most prevalent and aggressive form among all gliomas, associated with decimal prognosis due to it`s high invasive nature. GBM is also characterized by high recurrence rate and apoptosis resistance features which make the therapeutic targeting very challenging. Mitochondria are key cellular organelles that are acting as focal points in diverse array of cellular functions such as cellular energy metabolism, regulation of ion homeostasis, redox signaling and cell death. Eventual findings of mitochondrial dysfunction include preference of glycolysis over oxidative phosphorylation, enhanced reactive oxygen species generation and abnormal mitochondria mediated apoptotic machinery are frequently observed in various malignancies including gliomas. In particular, gliomas harbor mitochondrial structure abnormalities, genomic mutations in mtDNA, altered energy metabolism (Warburg effect) along with mutations in isocitrate dehydrogenase (IDH) enzyme. Numerous natural compounds have shown efficacy in the treatment of gliomas by targeting mitochondrial aberrant signaling cascades. Some of the natural compounds directly target the components of mitochondria whereas others act indirectly through modulating metabolic abnormalities that are consequence of the mitochondrial dysfunction. The present review offers a molecular insight into mitochondrial pathology in gliomas and therapeutic mechanisms of some of the promising natural compounds that target mitochondrial dysfunction. This review also sheds light on the challenges and possible ways to overcome the hurdles associated with these natural compounds to enter into the clinical market.

Tubb3 regulation by the Erk and Akt signaling pathways: a mechanism involved in the effect of arginine ADP-ribosyltransferase 1 (Art1) on apoptosis of colon carcinoma CT26 cells

The influence of the most important classical mono-ADP-ribosyltransferase, arginine ADP-ribosyltransferase 1 (Art1), on survival and apoptosis of colon carcinoma cells and the potential mechanisms have been partly discussed in our previous study but still need to be further studied. In this present study, Art1 of colon carcinoma CT26 cells was silenced with lentiviral vector-mediated short hairpin RNA (shRNA) or overexpressed with lentiviral vector-mediated complementary DNA (cDNA) and allograft transplant tumors are established in Balb/c mice. We verified Art1 knockdown increases apoptosis of CT26 cells transplant tumor; Art1 overexpression acts oppositely. Accordingly, growth of transplant tumors is inhibited in Art1 knockdown transplant tumors and increases in Art1 overexpression transplant tumors. Furthermore, activity of Akt and Erk cell signal pathways and expression of an apoptosis biomarker, βIII-tubulin (Tubb3), decrease when Art1 was silenced and increase when Art1 was overexpressed. Inhibiting Akt pathway or Erk pathway both downregulates expression of Tubb3 on protein and messenger RNA (mRNA) level, indicating that Tubb3 could be regulated by both Akt and Erk pathways, and plays a role in the influence of Art1 on apoptosis of Balb/c mice allograft transplant tumor. We also demonstrated that Bcl-2 family is not the responsible downstream factor of the Erk pathway in colon carcinoma cells which is undergoing apoptosis. These findings enrich the molecular mechanism for the function of Art1 in colon carcinoma and provide a complementary support for Art1 to be a potential therapeutic target of the treatment of this kind of malignant tumor.

Identification of the first inhibitor of the GBP1:PIM1 interaction. Implications for the development of a new class of anticancer agents against paclitaxel resistant cancer cells

Class III β-tubulin plays a prominent role in the development of drug resistance to paclitaxel by allowing the incorporation of the GBP1 GTPase into microtubules. Once in the cytoskeleton, GBP1 binds to prosurvival kinases such as PIM1 and initiates a signaling pathway that induces resistance to paclitaxel. Therefore, the inhibition of the GBP1:PIM1 interaction could potentially revert resistance to paclitaxel. A panel of 44 4-azapodophyllotoxin derivatives was screened in the NCI-60 cell panel. The result is that 31 are active and the comparative analysis demonstrated specific activity in paclitaxel-resistant cells. Using surface plasmon resonance, we were able to prove that NSC756093 is a potent in vitro inhibitor of the GBP1:PIM1 interaction and that this property is maintained in vivo in ovarian cancer cells resistant to paclitaxel. Through bioinformatics, molecular modeling, and mutagenesis studies, we identified the putative NSC756093 binding site at the interface between the helical and the LG domain of GBP1. According to our results by binding to this site, the NSC756093 compound is able to stabilize a conformation of GBP1 not suitable for binding to PIM1.

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.

The DNT-EST: a predictive embryonic stem cell-based assay for developmental neurotoxicity testing in vitro

As the developing brain is exquisitely vulnerable to chemical disturbances, testing for developmental neurotoxicity of a substance is an important aspect of characterizing its tissue specific toxicity. Mouse embryonic stem cells (mESCs) can be differentiated toward a neural phenotype, and this can be used as a model for early brain development. We developed a new in vitro assay using mESCs to predict adverse effects of chemicals and other compounds on neural development - the so-called DNT-EST. After treatment of differentiating stem cells for 48h or 72h, at two key developmental stages endpoint for neural differentiation, viability, and proliferation were assessed. As a reference, we similarly treated undifferentiated stem cells 2 days after plating for 48h or 72h in parallel to the differentiating stem cells. Here, we show that chemical testing of a training set comprising nine substances (six substances of known developmental toxicity and three without specific developmental neurotoxicity) enabled a mathematical prediction model to be formulated that provided 100% predictivity and accuracy for the given substances, including in leave-one-out cross-validation. The described test method can be performed within two weeks, including data analysis, and provides a prediction of the developmental neurotoxicity potency of a substance.

Class III β-tubulin overexpression within the tumor microenvironment is a prognostic biomarker for poor overall survival in ovarian cancer patients treated with neoadjuvant carboplatin/paclitaxel

Critics have suggested that neoadjuvant chemotherapy (NACT) followed by interval debulking may select for resistant clones or cancer stem cells when compared to primary cytoreduction. β-tubulins are chemotherapeutic targets of taxanes and epothilones. Class III β-tubulin overexpression has been linked to chemoresistance and hypoxia. Herein, we describe changes in class III β-tubulin in patients with advanced ovarian carcinoma in response to NACT, in relationship to clinical outcome, and between patients who underwent NACT versus primary debulking; we characterize in vitro chemosensitivity to paclitaxel/patupilone of cell lines established from this patient population, and class III β-tubulin expression following repeated exposure to paclitaxel. Using immunohistochemistry, we observed among 22 paired specimens obtained before/after NACT decreased expression of class III β-tubulin following therapy within stroma (p=0.07), but not tumor (p=0.63). Poor median overall survival was predicted by high levels of class III β-tubulin in both tumor (HR 3.66 [1.11,12.05], p=0.03) and stroma (HR 4.53 [1.28,16.1], p=0.02). Class III β-tubulin expression by quantitative-real-time-polymerase-chain-reaction was higher among patients who received NACT (n=12) compared to primary cytoreduction (n=14) (mean±SD fold-change: 491.2±115.9 vs. 224.1±55.66, p=0.037). In vitro subculture with paclitaxel resulted in class III β-tubulin upregulation, however, cell lines that overexpressed class III β-tubulin remained sensitive to patupilone. Overexpression of class III β-tubulin in patients dispositioned to NACT may thus identify an intrinsically aggressive phenotype, and predict poor overall survival and paclitaxel resistance. Decreases in stromal expression may represent normalization of the tumor microenvironment following therapy. Epothilones warrant study for patients who have received neoadjuvant carboplatin and paclitaxel.

Mitochondrial dysfunction in gliomas

Mitochondrial (mt) dysfunction in gliomas has been linked to abnormalities of mt energy metabolism, marked by a metabolic shift from oxidative phosphorylation to glycolysis ("Warburg effect"), disturbances in mt membrane potential regulation and apoptotic signaling, as well as to somatic mutations involving the Krebs cycle enzyme isocitrate dehydrogenase. Evolving biological concepts with potential therapeutic implications include interaction between microtubule proteins and mitochondria (mt) in the control of closure of voltage-dependent anion channels and in the regulation of mt dynamics and the mt-endoplasmic reticulum network. The cytoskeletal protein βIII-tubulin, which is overexpressed in malignant gliomas, has emerged as a prosurvival factor associated in part with mt and also as a marker of chemoresistance. Mt-targeted therapeutic strategies that are discussed include the following: (1) metabolic modulation with emphasis on dichloroacetate, a pyruvate dehydrogenase kinase inhibitor; (2) tumor cell death via apoptosis induced by tricyclic antidepressants, microtubule-modulating drugs, and small molecules or compounds capable of inflicting reactive oxygen species-dependent tumor cell death; and (3) pretreatment mt priming and mt-targeted prodrug cancer therapy.

Growth and differentiation factor 3 induces expression of genes related to differentiation in a model of cancer stem cells and protects them from retinoic acid-induced apoptosis

Misexpression of growth factors, particularly those related to stem cell-like phenotype, is often observed in several cancer types. It has been found to influence parameters of disease progression like cell proliferation, differentiation, maintenance of undifferentiated phenotype and modulation of the immune system. GDF3 is a TGFB family member associated with pluripotency and differentiation during embryonic development that has been previously reported to be re-expressed in a number of cancer types. However, its role in tumor development and progression has not been clarified yet. In this study we decipher the role of GDF3 in an in vitro model of cancer stem cells, NCCIT cells. By classical approach to study protein function combined with high-throughput technique for transcriptome analysis and differentiation assays we evaluated GDF3 as a potential therapeutic target. We observed that GDF3 robustly induces a panel of genes related to differentiation, including several potent tumor suppressors, without impacting the proliferative capacity. Moreover, we report for the first time the protective effect of GDF3 against retinoic acid-induced apoptosis in cells with stem cell-like properties. Our study implies that blocking of GDF3 combined with retinoic acid-treatment of solid cancers is a compelling direction for further investigations, which can lead to re-design of cancer differentiation therapies.

ERCC1, MLH1, MSH2, MSH6, and βIII-tubulin: resistance proteins associated with response and outcome to platinum-based chemotherapy in malignant pleural mesothelioma

INTRODUCTION

Platinum-based chemotherapy is besides the standard antifolate therapy with pemetrexed, the cornerstone for treatment of patients with malignant pleural mesothelioma (MPM), and its efficacy depends on several DNA repair enzymes. Therefore, these enzymes could be biomarkers for "tailoring" chemotherapy. This study evaluated enzymes involved in repair of platinum-caused DNA damage, potentially resulting in a biomarker panel associated with patient response and outcome to platinum-based chemotherapy.

MATERIAL AND METHODS

Pre- or posttreatment specimens from a total of 103 patients with MPM who were undergoing first-line chemotherapy were tested separately. Immunohistochemistry for ERCC1 (endonuclease excision repair cross-complementing 1), MLH1 (MutL homologue 1), MutS homologue (MSH) 2, MSH6, and βIII-tubulin protein expression, and pyrosequencing for ERCC1 codon 118 and C8092A polymorphisms were performed, and their results were correlated to clinicopathologic data.

RESULTS

ERCC1, MLH1, MSH2, MSH6, and βIII-tubulin were expressed in human MPM specimens at different intensities. When considering only pretreatment specimens, MSH6 protein levels were correlated to progression during chemotherapy (P = .0281). MLH1 protein levels (P = .0205), and ERCC1 codon 118 polymorphisms (P ≤ .0001) were significantly associated with progression-free survival. A significant association between ERCC1 protein levels and overall survival was noted (P = .032). Analyses of posttreatment specimens revealed significant associations between βIII-tubulin protein levels and progression-free survival (P = .0066). ERCC1 C8092A polymorphisms were significantly associated with progression-free survival and overall survival (P = .0463 and P = .0080, respectively) in this group.

CONCLUSIONS

Enzymes involved in DNA repair mechanisms are associated with patient response and outcome to platinum-based chemotherapy. Their assessment may be a helpful tool to tailor platinum-based chemotherapy of MPM patients who might expect the largest clinical benefit. Prospective validation of this biomarker panel is warranted.

Evidence for predictive role of BRCA1 and bTUBIII in gastric cancer

Sensitivity of gastric cancer (GC) to conventional cytotoxic therapy may be at least in part attributed to molecular features of the tumor cells. We analyzed all patients with metastatic GC treated in the N.N. Petrov Institute of Oncology (St. Petersburg) within years 1999-2010 and identified 65 cases with evaluable treatment response and available biological material. Two of 65 patients (3 %) carried germ-line BRCA1 5382insC mutation and demonstrated particularly pronounced response to the treatment; both of their tumors showed loss of the remaining BRCA1 allele, thus confirming the causative role of BRCA1 heterozygosity in GC predisposition. RNA expression of TS, DPD, BRCA1, ERCC, TOP2A and bTUBIII was analyzed in the remaining 63 tumors. Low BRCA1 expression was associated with increased response rate [6/9 (67 %) vs. 17/54 (32 %), p = 0.04]. Low bTUBIII level correlated with the improved probability of tumor response [21/49 (43 %) vs. 1/13 (8 %), p = 0.02] and prolonged overall survival (10.5 vs. 7.1 months, p = 0.02); this trend was maintained both for taxane-containing and for taxane-free drug combinations. We conclude that GC should be considered as a part of BRCA1-related hereditary cancer syndrome. Tumors with BRCA1 inactivation and low bTUBIII expression demonstrate improved response to cytotoxic therapy.

Correlation between microtubule-associated gene expression and chemosensitivity of patients with stage II non-small cell lung cancer

The aim of this study was to explore the correlation between mRNA expression of β-tubulin-III and stathmin in patients with stage II non-small cell lung cancer (NSCLC) and the chemosensitivity to Navelbine plus cisplatin (NP), as well as to provide a basis for personalized treatment. A single-gene quantitative test was performed to detect the mRNA expression of β-tubulin-III and stathmin in the tumor tissue of patients with stage II NSCLC. All the patients underwent NP treatment following surgery and were followed-up to record their disease-free survival (DFS) and overall survival (OS). Statistical analyses were conducted to investigate the correlation between β-tubulin-III and stathmin mRNA expression and DFS and OS in the patients. β-tubulin-III mRNA expression was associated with OS in the 73 patients (P=0.003) and DFS was correlated with β-tubulin-III mRNA expression and lymphatic metastasis (P<0.01). Stathmin mRNA expression was not correlated with OS or DFS (P>0.05). OS and DFS were longer in the patients with low β-tubulin-III mRNA expression than in those with high β-tubulin-III mRNA expression (P<0.01); there was no significant change in OS and DFS between the patients with high and low mRNA expression of stathmin (P>0.05). The mRNA expression levels of β-tubulin-III in the tumor tissue of patients with stage II NSCLC may be considered as an index of prognosis and chemosensitivity, as well as a reference for personalized chemotherapeutic applications in patients.

βIII-Tubulin: biomarker of taxane resistance or drug target?

INTRODUCTION

βIII-Tubulin (TUBB3) is predominantly expressed in neurons of the central and peripheral nervous systems, while in normal non-neoplastic tissues it is barely detectable. By contrast, this cytoskeletal protein is abundant in a wide range of tumors. βIII-Tubulin is linked to dynamic instability of microtubules (MTs), weakening the effects of agents interfering with MT polymerization. Based on this principle, early studies introduced the classical theory linking βIII-tubulin with a mechanism of counteracting taxane activity and accordingly, prompted its investigation as a predictive biomarker of taxane resistance.

AREAS COVERED

We reviewed 59 translational studies, including cohorts from lung, ovarian, breast, gastric, colorectal and various miscellaneous cancers subject to different chemotherapy regimens.

EXPERT OPINION

βIII-Tubulin functions more as a prognostic factor than as a predictor of response to chemotherapy. We believe this view can be explained by βIII-tubulin's association with prosurvival pathways in the early steps of the metastatic process. Its prognostic response increases if combined with additional biomarkers that regulate its expression, since βIII-tubulin can be expressed in conditions, such as estrogen exposure, unrelated to survival mechanisms and without any predictive activity. Additional avenues for therapeutic intervention could emerge if drugs are designed to directly target βIII-tubulin and its mechanism of regulation.