High TUBB3 expression, an independent prognostic marker in patients with early non-small cell lung cancer treated by preoperative chemotherapy, is regulated by K-Ras signaling pathway

βIII-tubulin overexpression is linked to aggressive tumor features and shortened survival in clear cell renal cell carcinoma

AIMS

βIII-tubulin (TUBB3) is a microtubule component overexpression of which is found in many solid cancer types, often linked to poor patient prognosis, and has been suggested to predict failure of microtubule-targeting chemotherapeutics. This study was designed to determine prevalence and prognostic impact of TUBB3 expression in kidney cancers.

METHODS AND RESULTS

A tissue microarray (TMA) containing more than 1,200 renal tumors was analyzed by immunohistochemistry. TUBB3 expression varied markedly between the different histological subtypes and was more frequent in 105 papillary cancers (75.2 %, p < 0.0001), 38 oncocytomas (52.6 %, p < 0.0001), and 22 chromophobic carcinomas (36.4 %, p = 0.1221) than in 555 clear cell RCC (16.4 %). In clear cell cancers, strong TUBB3 positivity was linked to high Fuhrman grade (p < 0.0001), advanced stage (0.002), nodal metastases (p = 0.0433), hematogenous metastases (p = 0.0016), and shortened overall survival (p < 0.0001). Associations with outcome and tumor phenotype were inversely for papillary RCC, where TUBB3 immunostaining was linked to low tumor stage (p = 0.0012) and prolonged survival (p = 0.0043).

CONCLUSIONS

TUBB3 expression levels and their effects are strikingly different between ccRCC and papillary RCC. These differences may be caused by differences in VHL function between these RCC subtypes, because VHL (like TUBB3) is another strong regulator of microtubule function.

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.

Plasma membrane proteomics of human breast cancer cell lines identifies potential targets for breast cancer diagnosis and treatment

The use of broad spectrum chemotherapeutic agents to treat breast cancer results in substantial and debilitating side effects, necessitating the development of targeted therapies to limit tumor proliferation and prevent metastasis. In recent years, the list of approved targeted therapies has expanded, and it includes both monoclonal antibodies and small molecule inhibitors that interfere with key proteins involved in the uncontrolled growth and migration of cancer cells. The targeting of plasma membrane proteins has been most successful to date, and this is reflected in the large representation of these proteins as targets of newer therapies. In view of these facts, experiments were designed to investigate the plasma membrane proteome of a variety of human breast cancer cell lines representing hormone-responsive, ErbB2 over-expressing and triple negative cell types, as well as a benign control. Plasma membranes were isolated by using an aqueous two-phase system, and the resulting proteins were subjected to mass spectrometry analysis. Overall, each of the cell lines expressed some unique proteins, and a number of proteins were expressed in multiple cell lines, but in patterns that did not always follow traditional clinical definitions of breast cancer type. From our data, it can be deduced that most cancer cells possess multiple strategies to promote uncontrolled growth, reflected in aberrant expression of tyrosine kinases, cellular adhesion molecules, and structural proteins. Our data set provides a very rich and complex picture of plasma membrane proteins present on breast cancer cells, and the sorting and categorizing of this data provides interesting insights into the biology, classification, and potential treatment of this prevalent and debilitating disease.

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.

Mutations of EGFR or KRAS and expression of chemotherapy-related genes based on small biopsy samples in stage IIIB and IV inoperable non-small cell lung cancer

PURPOSES

Epidermal growth factor receptor (EGFR) and KRAS mutations may predict the outcome of targeted drug therapy and also may be associated with the efficacy of chemotherapy in patients with non-small cell lung cancer (NSCLC). This report investigated the relation of EGFR or KRAS mutation and expression of chemotherapy-related genes, including excision repair cross-complementing 1 (ERCC1), thymidylate synthetase (TYMS), ribonucleotide reductase subunit M1 (RRM1) and class III β-tubulin (TUBB3), as a potential explanation for these observations.

METHODS

A total of 143 patients with stage IIIB and IV NSCLC from bronchoscopy or percutaneous lung biopsy obtained tumor samples were analyzed concurrently for EGFR or KRAS mutations, and mRNA expression of ERCC1, TYMS, RRM1 and TUBB3. EGFR or KRAS mutations were detected with xTAG liquidchip technology (xTAG-LCT), and mRNA expression levels of four genes were detected by branched DNA-liquidchip technology (bDNA-LCT).

RESULTS

Of 143 patients, 63 tumors were positive for EGFR-activating mutations, and 16 tumors were positive for KRAS mutations. EGFR-activating mutations are more frequent in females, adenocarcinoma and non-smokers patients, and KRAS mutations are more frequent in smoking patients. ERCC1 mRNA levels were significantly associated with histological type and tumor differentiation, whereas TYMS levels were significantly associated with age. NSCLC specimens that harboring EGFR-activating mutations are more likely to express low ERCC1 and high TUBB3 mRNA levels, whereas tumors from patients with NSCLC harboring KRAS mutation are more likely to express high ERCC1 mRNA levels.

CONCLUSIONS

Mutations and expression of chemotherapy-related genes may provide a basis for the selection of suitable molecular markers for individual treatment in a population with stage IIIB and IV NSCLC.

Microtubules and their role in cellular stress in cancer

Microtubules are highly dynamic structures, which consist of α- and β-tubulin heterodimers, and are involved in cell movement, intracellular trafficking, and mitosis. In the context of cancer, the tubulin family of proteins is recognized as the target of the tubulin-binding chemotherapeutics, which suppress the dynamics of the mitotic spindle to cause mitotic arrest and cell death. Importantly, changes in microtubule stability and the expression of different tubulin isotypes as well as altered post-translational modifications have been reported for a range of cancers. These changes have been correlated with poor prognosis and chemotherapy resistance in solid and hematological cancers. However, the mechanisms underlying these observations have remained poorly understood. Emerging evidence suggests that tubulins and microtubule-associated proteins may play a role in a range of cellular stress responses, thus conferring survival advantage to cancer cells. This review will focus on the importance of the microtubule-protein network in regulating critical cellular processes in response to stress. Understanding the role of microtubules in this context may offer novel therapeutic approaches for the treatment of cancer.

Expression of ERCC1, TYMS, TUBB3, RRM1 and TOP2A in patients with esophageal squamous cell carcinoma: A hierarchical clustering analysis

The aim of the present study was to investigate the correlation between the expression levels of excision repair cross complementing 1 (ERCC1), thymidylate synthase (TYMS), class III β-tubulin (TUBB3), ribonucleoside-diphosphate reductase (RRM1) and topoisomerase IIα (TOP2A) with the clinical characteristics of patients with esophageal squamous cell carcinoma (ESCC). A total of 29 ESCC tissue samples were collected from patients that had not previously received systematic treatment. The expression levels of ERCC1, TYMS, TUBB3, RRM1 and TOP2A were determined using a microarray technique, while Spearman’s rank correlation analysis was used to determine the strength of the correlations between the expression levels of the biomarkers and the pathogenesis of esophageal cancer. High expression levels of TYMS and TOP2A were observed in 24% of the samples and high expression levels of TUBB3 and RRM1 were identified in 7% of the samples. Hierarchical clustering analysis of these biomarkers enabled the samples to be grouped. Group 1 patients exhibited low expression levels of TYMS, RRM1 and TOP2A and high expression of ERCC1 and TUBB3, while group 2 samples had low expression levels of ERCC1 and TUBB3 and high expression levels of TYMS, RRM1 and TOP2A. Analysis using Fisher’s exact test demonstrated a statistically significant difference in the severity of carcinoma invasion between the two groups (P<0.05), however, no significant differences were identified with regard to the clinical stage or lymphatic metastasis (P>0.05). Therefore, hierarchical clustering analysis indicated that the expression levels of ERCC1, TYMS, TUBB3, RRM1 and TOP2A were closely associated with the clinical characteristics of patients with ESCC.

Induction of the ganglion cell differentiation program in human retinal progenitors before cell cycle exit

BACKGROUND

Despite the disease relevance, understanding of human retinal development lags behind that of other species. We compared the kinetics of gene silencing or induction during ganglion cell development in human and murine retina.

RESULTS

Induction of POU4F2 (BRN3B) marks ganglion cell commitment, and we detected this factor in S-phase progenitors that had already silenced Cyclin D1 and VSX2 (CHX10). This feature was conserved in human and mouse retina, and the fraction of Pou4f2+ murine progenitors labeled with a 30 min pulse of BrdU matched the fraction of ganglion cells predicted to be born in a half-hour period. Additional analysis of 18 markers revealed many with conserved kinetics, such as the POU4F2 pattern above, as well as the surprising maintenance of "cell cycle" proteins KI67, PCNA, and MCM6 well after terminal mitosis. However, four proteins (TUBB3, MTAP1B, UCHL1, and RBFOX3) showed considerably delayed induction in human relative to mouse retina, and two proteins (ISL1, CALB2) showed opposite kinetics, appearing on either side of terminal mitosis depending on the species.

CONCLUSION

With some notable exceptions, human and murine ganglion cell differentiation show similar kinetics, and the data add weight to prior studies supporting the existence of biased ganglion cell progenitors.

First line treatment of advanced non-small-cell lung cancer - specific focus on albumin bound paclitaxel

Lung cancer is the leading cause of cancer mortality worldwide in both men and women. Non-small-cell lung cancer (NSCLC) is the most common type of lung cancer, accounting for more than 80% of cases. Paclitaxel has a broad spectrum of activity against various malignancies, including NSCLC. Paclitaxel is poorly soluble in water and thus, until recently, its commercially available preparations contained a non-ionic solvent Cremophor EL®. Cremophor EL® improves the solubility of paclitaxel and allows its intravenous administration. However, certain side-effects associated with paclitaxel, such as hypersensitivity reactions, myelosuppression, and peripheral neuropathy, are known to be worsened by Cremophor®. Nanoparticle albumin-bound paclitaxel ([nab-paclitaxel] ABRAXANE® ABI-007) is a new generation formulation of paclitaxel that obviates the need for Cremophor®, resulting in a safer and faster infusion without requiring the use of premedications to avoid hypersensitivity. Albumin-binding receptor-mediated delivery and lack of sequestering Cremophor® micelles allow higher intratumoral concentration of pharmacologically active paclitaxel. Multiple clinical trials have demonstrated a superior tolerability profile of nab-paclitaxel in comparison to solvent-bound paclitaxel (sb-paclitaxel). A recent Phase III trial compared the effects of weekly nab-paclitaxel in combination with carboplatin versus sb-paclitaxel in combination with carboplatin given every 3 weeks for first line treatment of NSCLC. This trial highlights the weekly nab-paclitaxel combination as an alternate treatment option for NSCLC, with higher response rate in squamous cell NSCLC and longer survival in elderly patients. This review will focus on the properties of nab-paclitaxel and its use in the first line treatment of NSCLC.

Immunohistochemistry evaluation of biomarker expression in non-small cell lung cancer (Pharmacogenoscan study)

OBJECTIVES

Platinum-based chemotherapy regimens are the standard treatment of non-small cell lung cancer (NSCLC). In this study, our objective was to identify tumor tissue protein biomarkers that might predict a benefit from these treatments.

MATERIALS AND METHODS

The Pharmacogenoscan study prospectively included consecutive chemotherapy-naive NSCLC patients at any stage between 2005 and 2010 at six hospitals in the Rhône-Alpes-Auvergne region of France. Of the 537 patients in the full analysis set, 460 had a complete histological diagnosis. We used the tumor tissue samples for an immunohistochemical evaluation of eight biomarkers: ERCC1, BRCA1, p53, p27kip1, class III β-tubulin (TUBB3), Bax, Fas, and FasL. We looked for associations between these biomarkers and the disease control rate (DCR) after 2/3 cycles of platinum-based chemotherapy, progression-free survival (PFS), and overall survival (OS).

RESULTS

A tissue sample adequate for testing at least one biomarker was available for 289 patients. We found no significant association between biomarker expression levels and clinical or pathological variables; TUBB3 showed a trend toward higher expression in adenocarcinomas (P=0.005). For none of the biomarkers were significant associations found between expression level and DCR, PFS, or OS. TUBB3-negative and FasL-negative tumors showed associations of borderline significance with higher DCR.

CONCLUSION

In a large cohort of patients with predominantly advanced or metastatic NSCLC, none of eight tested immunohistochemical biomarkers predicted the chemotherapy response or survival. Our data indicate limited usefulness of protein biomarkers in metastatic NSCLC and a need for further research based on molecular signatures of greater complexity.

High expression of class III β-tubulin in small cell lung carcinoma

Class III β-tubulin (TUBB3) is emerging as a biomarker in a number of cancers. TUBB3 has been shown to be a prognostic indicator of more aggressive disease and a predictor of resistance to taxanes and vinca alkaloids. To date, there is little data on TUBB3 expression in small cell lung carcinoma (SCLC). The primary objective of this study was to determine the expression of TUBB3 in SCLC. Immunohistochemical staining of SCLC tumor specimens was performed using standard procedures. Expression of TUBB3 was determined as a composite of the percentage of malignant cells staining positive and the intensity of staining. Clinical and tumor data for each patient was compared with the degree of TUBB3 expression. A total of 66 SCLCs were evaluable for TUBB3 expression. The majority of specimens (n=56, 85%) had high expression of TUBB3. Only 4.5% (n=3) had low expression of TUBB3. The mean distribution of positive staining for the specimens was 87.3±1.8% (mean ± SE). Specimens from core biopsies were significantly more likely to have high TUBB3 expression when compared with fine needle aspirates (P=0.004). There were no other significant findings when comparing clinical or tumor characteristics. Overall, we found that expression of TUBB3 in SCLC is higher than expected. Innate resistance to microtubule inhibitors, such as the taxanes and vinca alkaloids, may be associated with this finding. Attempts at microtubule inhibition with novel agents may be able to overcome this resistance mechanism. Further evaluation of TUBB3 as a biomarker in SCLC is warranted.

The role of the dysfunctional akt-related pathway in cancer: establishment and maintenance of a malignant cell phenotype, resistance to therapy, and future strategies for drug development

Akt serine/threonine kinases, or PKB, are key players in the regulation of a wide variety of cellular activities, such as growth, proliferation, protection from apoptotic injuries, control of DNA damage responses and genome stability, metabolism, migration, and angiogenesis. The Akt-related pathway responds to the stimulation mediated by growth factors, cytokines, hormones, and several nutrients. Akt is present in three isoforms: Akt1, Akt2, and Akt3, which may be alternatively named PKB α , PKB β , and PKB γ , respectively. The Akt isoforms are encoded on three diverse chromosomes and their biological functions are predominantly distinct. Deregulations in the Akt-related pathway were observed in many human maladies, including cancer, cardiopathies, neurological diseases, and type-2 diabetes. This review discusses the significance of the abnormal activities of the Akt axis in promoting and sustaining malignancies, along with the development of tumor cell populations that exhibit enhanced resistance to chemo- and/or radiotherapy. This occurrence may be responsible for the relapse of the disease, which is unfortunately very often related to fatal consequences in patients.

[Correlation between expression of TUBB3/STMN1 and EGFR signaling pathway in non-small cell lung cancer]

背景与目的

已有研究表明分子标志物在指导肺癌个体化治疗中起着重要作用。本研究旨在探讨非小细胞肺癌（non-small cell lung cancer, NSCLC）抗微管类药物靶点TUBB3（tubulin, beta 3 class Ⅲ)/STMN1（stathmin 1）基因表达水平与EGFR（epidermal growth factor receptor）、KRAS（Kirsten rat sarcoma viral oncogene homolog）、BRAF（v-raf murine sarcoma viral oncogene homolog B）、PI3K（phosphatidylinositol-4, 5-bisphosphate 3-kinase）基因突变的相关性，为NSCLC预后及药物疗效判断提供参考依据。

方法

回顾性分析我院经病理确诊的46例NSCLC患者手术切除的肿瘤标本，通过分支DNA-液相芯片法检测TUBB3、STMN1基因mRNA表达水平，通过xTAG液相芯片法检测EGFR、KRAS、BRAF、PI3K基因突变，对检测结果应用SPSS 19.0软件采用Spearman相关进行分析基因表达与基因突变的关系。

结果

抗微管靶点TUBB3和STMN1存在很强的共表达性，TUBB3基因高表达时，STMN1趋向于高表达（P=0.006）。EGFR E21突变与TUBB3存在负相关关系：EGFR E21无突变时TUBB3趋向于高表达（P=0.004, 6）。KRAS E2突变与STMN1存在正相关关系：KRAS E2突变时STMN1趋向于高表达（P=0.038, 6）。

结论

抗微管耐药相关因子TUBB3和STMN1与EGFR通路的关键因子突变相关，提示了EGFR突变和KRAS突变是调控TUBB3/STMN1表达的重要因素，为研究化疗药物耐药性提供了重要的参考因素。

Cigarette smoke mediates epigenetic repression of miR-487b during pulmonary carcinogenesis

MicroRNAs are critical mediators of stem cell pluripotency, differentiation, and malignancy. Limited information exists regarding microRNA alterations that facilitate initiation and progression of human lung cancers. In this study, array techniques were used to evaluate microRNA expression in normal human respiratory epithelia and lung cancer cells cultured in the presence or absence of cigarette smoke condensate (CSC). Under relevant exposure conditions, CSC significantly repressed miR-487b. Subsequent experiments demonstrated that miR-487b directly targeted SUZ12, BMI1, WNT5A, MYC, and KRAS. Repression of miR-487b correlated with overexpression of these targets in primary lung cancers and coincided with DNA methylation, de novo nucleosome occupancy, and decreased H2AZ and TCF1 levels within the miR-487b genomic locus. Deoxy-azacytidine derepressed miR-487b and attenuated CSC-mediated silencing of miR-487b. Constitutive expression of miR-487b abrogated Wnt signaling, inhibited in vitro proliferation and invasion of lung cancer cells mediated by CSC or overexpression of miR-487b targets, and decreased growth and metastatic potential of lung cancer cells in vivo. Collectively, these findings indicate that miR-487b is a tumor suppressor microRNA silenced by epigenetic mechanisms during tobacco-induced pulmonary carcinogenesis and suggest that DNA demethylating agents may be useful for activating miR-487b for lung cancer therapy.

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.

Serum levels of TUBB3 correlate with clinical outcome in Chinese patients with advanced gastric cancer receiving first-line paclitaxel plus capecitabine

The overexpression of β-tubulin III (TUBB3) in tumor tissues was reversely related with the efficacy of paclitaxel and clinical outcome in different cancers. In this study, we aimed to investigate the association between serum levels of TUBB3 and clinical outcome in advanced gastric cancer patients receiving first-line paclitaxel plus capecitabine. One hundred and twenty-eight advanced gastric cancer patients receiving first-line paclitaxel plus capecitabine in Peking University Cancer Hospital from December 2006 to October 2010 were enrolled in the study. Serum samples from 32 healthy individuals were used as controls. TUBB3 expression level in advanced gastric cancer was significantly higher than that in healthy control group (31.6 ± 17.8 ng/mL vs. 16.9 ± 3.8 ng/mL, p < 0.001). For all patients, the clinical benefit rate (CBR), median progression-free survival (PFS), and overall survival (OS) were 55.6 %, 179 and 306 days, respectively. The CBR, median PFS, and OS in patients with low (n = 27) and high levels (n = 101) of TUBB3 were 95.8 %/45.1 % (low vs. high, p < 0.001), 190 days/166 days (p = 0.064), and 360 days/297 days (p = 0.023), respectively. Cox multivariate regression analysis demonstrated that the serum levels of TUBB3 were an independent prognostic factor for advanced gastric cancer patients (HR = 1.950; 95 % CI, 1.242-3.062; p = 0.004). This study indicated that low levels of TUBB3 in serum could predict better response and survival for advanced gastric cancer patients receiving paclitaxel plus capecitabine, which could be used to select patients who would benefit from this regimen.