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

Proteomic Assessment of SKBR3/HER2+ Breast Cancer Cellular Response to Lapatinib and Investigational Ipatasertib Kinase Inhibitors

Modern cancer treatment approaches aim at achieving cancer remission by using targeted and personalized therapies, as well as harnessing the power of the immune system to recognize and eliminate the cancer cells. To overcome a relatively short-lived response due to the development of resistance to the administered drugs, combination therapies have been pursued, as well. To expand the outlook of combination therapies, the objective of this study was to use high-throughput data generation technologies such as mass spectrometry and proteomics to investigate the response of HER2+ breast cancer cells to a mixture of two kinase inhibitors that has not been adopted yet as a standard treatment regime. The broader landscape of biological processes that are affected by inhibiting two major pathways that sustain the growth and survival of cancer cells, i.e., EGFR and PI3K/AKT, was investigated by treating SKBR3/HER2+ breast cancer cells with Lapatinib or a mixture of Lapatinib/Ipatasertib small molecule drugs. Changes in protein expression and/or activity in response to the drug treatments were assessed by using two complementary quantitative proteomic approaches based on peak area and peptide spectrum match measurements. Over 900 proteins matched by three unique peptide sequences (FDR<0.05) were affected by the exposure of cells to the drugs. The work corroborated the anti-proliferative activity of Lapatinib and Ipatasertib, and, in addition to cell cycle and growth arrest processes enabled the identification of several multi-functional proteins with roles in cancer-supportive hallmark processes. Among these, immune response, adhesion and migration emerged as particularly relevant to the ability to effectively suppress the proliferation and dissemination of cancer cells. The supplementation of Lapatinib with Ipatasertib further affected the expression or activity of additional transcription factors and proteins involved in gene expression, trafficking, DNA repair, and development of multidrug resistance. Furthermore, over fifty of the affected proteins represented approved or investigational targets in the DrugBank database, which through their protein-protein interaction networks can inform the selection of effective therapeutic partners. Altogether, our findings exposed a broad plethora of yet untapped opportunities that can be further explored for enhancing the anti-cancer effects of each drug as well as of many other multi-drug therapies that target the EGFR/ERBB2 and PI3K/AKT pathways. The data are available via ProteomeXchange with identifier PXD051094.

Hypoxia-induced activation of NDR2 underlies brain metastases from Non-Small Cell Lung Cancer

The molecular mechanisms induced by hypoxia are misunderstood in non-small cell lung cancer (NSCLC), and above all the hypoxia and RASSF1A/Hippo signaling relationship. We confirmed that human NSCLC (n = 45) as their brain metastases (BM) counterpart are hypoxic since positive with CAIX-antibody (target gene of Hypoxia-inducible factor (HIF)). A severe and prolonged hypoxia (0.2% O2, 48 h) activated YAP (but not TAZ) in Human Bronchial Epithelial Cells (HBEC) lines by downregulating RASSF1A/kinases Hippo (except for NDR2) regardless their promoter methylation status. Subsequently, the NDR2-overactived HBEC cells exacerbated a HIF-1A, YAP and C-Jun-dependent-amoeboid migration, and mainly, support BM formation. Indeed, NDR2 is more expressed in human tumor of metastatic NSCLC than in human localized NSCLC while NDR2 silencing in HBEC lines (by shRNA) prevented the xenograft formation and growth in a lung cancer-derived BM model in mice. Collectively, our results indicated that NDR2 kinase is over-active in NSCLC by hypoxia and supports BM formation. NDR2 expression is thus a useful biomarker to predict the metastases risk in patients with NSCLC, easily measurable routinely by immunohistochemistry on tumor specimens.

Clinicopathological significance of TUBB3 in upper tract urothelial carcinoma and possible application in urine cytology

βIII-Tubulin, encoded by the TUBB3 gene, is a microtubule protein. We previously reported that TUBB3 is overexpressed in renal cell carcinoma. We investigated the clinicopathological significance of TUBB3 in upper tract urothelial carcinoma (UTUC) by immunohistochemistry. In normal tissue, TUBB3 expression was weak or absent. In contrast, TUBB3 overexpression was observed in urothelial carcinoma (UC) tissues in 51 (49%) of 103 UTUC cases. TUBB3 overexpression was associated with nodular/flat morphology, high-grade disease, high T stage, and a poor prognosis. Similar results were obtained in The Cancer Genome Atlas bladder cancer cohort. TUBB3 expression was also associated with high Ki-67 labeling index, CD44v9, HER2, EGFR, and p53 expression in UTUC. Among representative cancer-related molecules, TUBB3 was an independent predictor of progression-free survival and high-grade UC. Finally, using urine cytology samples, we analyzed TUBB3 expression by immunocytochemistry. TUBB3 expression was more frequently found in UC cells than in nonneoplastic cells. The diagnostic accuracy of urine cytology was improved when combined with TUBB3 immunostaining. The findings suggest the importance of TUBB3 in tumor progression and its potential application as a biomarker for high-grade disease and the prognosis of UC. Moreover, combination with TUBB3 immunostaining might improve the diagnostic accuracy of urine cytology.

In Silico Exploration of Microtubule Agent Griseofulvin and Its Derivatives Interactions with Different Human β-Tubulin Isotypes

Tubulin isotypes are known to regulate microtubule stability and dynamics, as well as to play a role in the development of resistance to microtubule-targeted cancer drugs. Griseofulvin is known to disrupt cell microtubule dynamics and cause cell death in cancer cells through binding to tubulin protein at the taxol site. However, the detailed binding mode involved molecular interactions, and binding affinities with different human β-tubulin isotypes are not well understood. Here, the binding affinities of human β-tubulin isotypes with griseofulvin and its derivatives were investigated using molecular docking, molecular dynamics simulation, and binding energy calculations. Multiple sequence analysis shows that the amino acid sequences are different in the griseofulvin binding pocket of βI isotypes. However, no differences were observed at the griseofulvin binding pocket of other β-tubulin isotypes. Our molecular docking results show the favorable interaction and significant affinity of griseofulvin and its derivatives toward human β-tubulin isotypes. Further, molecular dynamics simulation results show the structural stability of most β-tubulin isotypes upon binding to the G1 derivative. Taxol is an effective drug in breast cancer, but resistance to it is known. Modern anticancer treatments use a combination of multiple drugs to alleviate the problem of cancer cells resistance to chemotherapy. Our study provides a significant understanding of the involved molecular interactions of griseofulvin and its derivatives with β-tubulin isotypes, which may help to design potent griseofulvin analogues for specific tubulin isotypes in multidrug-resistance cancer cells in future.

Quantitative Evaluation of Stem-like Markers of Human Glioblastoma Using Single-Cell RNA Sequencing Datasets

Targeting glioblastoma (GBM) stem-like cells (GSCs) is a common interest in both the laboratory investigation and clinical treatment of GBM. Most of the currently applied GBM stem-like markers lack validation and comparison with common standards regarding their efficiency and feasibility in various targeting methods. Using single-cell RNA sequencing datasets from 37 GBM patients, we obtained a large pool of 2173 GBM stem-like marker candidates. To evaluate and select these candidates quantitatively, we characterized the efficiency of the candidate markers in targeting the GBM stem-like cells by their frequencies and significance of being the stem-like cluster markers. This was followed by further selection based on either their differential expression in GBM stem-like cells compared with normal brain cells or their relative expression level compared with other expressed genes. The cellular location of the translated protein was also considered. Different combinations of selection criteria highlight different markers for different application scenarios. By comparing the commonly used GSCs marker CD133 (PROM1) with markers selected by our method regarding their universality, significance, and abundance, we revealed the limitations of CD133 as a GBM stem-like marker. Overall, we propose BCAN, PTPRZ1, SOX4, etc. for laboratory-based assays with samples free of normal cells. For in vivo targeting applications that require high efficiency in targeting the stem-like subtype, the ability to distinguish GSCs from normal brain cells, and a high expression level, we recommend the intracellular marker TUBB3 and the surface markers PTPRS and GPR56.

βIII-tubulin suppression enhances the activity of Amuvatinib to inhibit cell proliferation in c-Met positive non-small cell lung cancer cells

Non-Small Cell Lung Carcinoma (NSCLC) remains a leading cause of cancer death. Resistance to therapy is a significant problem, highlighting the need to find new ways of sensitising tumour cells to therapeutic agents. βIII-tubulin is associated with aggressive tumours and chemotherapy resistance in a range of cancers including NSCLC. βIII-tubulin expression has been shown to impact kinase signalling in NSCLC cells. Here, we sought to exploit this interaction by identifying co-activity between βIII-tubulin suppression and small-molecule kinase inhibitors. To achieve this, a forced-genetics approach combined with a high-throughput drug screen was used. We show that activity of the multi-kinase inhibitor Amuvatinib (MP-470) is enhanced by βIII-tubulin suppression in independent NSCLC cell lines. We also show that this compound significantly inhibits cell proliferation among βIII-tubulin knockdown cells expressing the receptor tyrosine kinase c-Met. Together, our results highlight that βIII-tubulin suppression combined with targeting specific receptor tyrosine kinases may represent a novel therapeutic approach for otherwise difficult-to-treat lung carcinomas.

Response to neoadjuvant paclitaxel predicts survival in anaplastic thyroid carcinoma

The clinical utilities of paclitaxel in anaplastic thyroid carcinoma (ATC) have been reported. The current study investigated the outcomes in ATC patients treated by paclitaxel as neoadjuvant setting. Furthermore, the prognostic factor for overall survival (OS) and predictive marker for response to paclitaxel were investigated. Records of ATC patients treated by paclitaxel as neoadjuvant setting in our hospital were reviewed. The median OS for the patients with (n = 43) and without (n = 23) resection were 14.7 (95% CI, 11.0-21.7) and 4.2 (95% CI, 3.0-5.4) months, respectively (p < 0.001). Univariate analysis identified the factors of stage (p = 0.028), prognostic index (PI) ≥2 (p < 0.001), response to paclitaxel (p = 0.007), resection (p < 0.001), and radiotherapy (p < 0.001) to be associated with OS, and multivariate analysis revealed that the factors of PI ≥2 [hazard ratio (HR), 2.406 (95% CI, 1.096-5.281), p = 0.029], response to paclitaxel [HR, 0.423 (95% CI, 0.193-0.930), p = 0.032], resection [HR, 0.316 (95% CI, 0.129-0.773), p = 0.012], and radiotherapy [HR, 0.229 (95% CI, 0.100-0.526), p < 0.001] were independent prognostic factors of OS. There were no significant predictive factors for response to paclitaxel in baseline characteristics. PI ≥2, response to paclitaxel, resection, and radiotherapy were independent prognostic factors in ATC patients treated with paclitaxel as neoadjuvant setting. It is important to investigate predictor for response to paclitaxel for improving resectability and prognosis in ATC.

βIII-Tubulin Gene Regulation in Health and Disease

Microtubule proteins form a dynamic component of the cytoskeleton, and play key roles in cellular processes, such as vesicular transport, cell motility and mitosis. Expression of microtubule proteins are often dysregulated in cancer. In particular, the microtubule protein βIII-tubulin, encoded by the TUBB3 gene, is aberrantly expressed in a range of epithelial tumours and is associated with drug resistance and aggressive disease. In normal cells, TUBB3 expression is tightly restricted, and is found almost exclusively in neuronal and testicular tissues. Understanding the mechanisms that control TUBB3 expression, both in cancer, mature and developing tissues will help to unravel the basic biology of the protein, its role in cancer, and may ultimately lead to the development of new therapeutic approaches to target this protein. This review is devoted to the transcriptional and posttranscriptional regulation of TUBB3 in normal and cancerous tissue.

Interpreting Functional Impact of Genetic Variations by Network QTL for Genotype–Phenotype Association Study

An enormous challenge in the post-genome era is to annotate and resolve the consequences of genetic variation on diverse phenotypes. The genome-wide association study (GWAS) is a well-known method to identify potential genetic loci for complex traits from huge genetic variations, following which it is crucial to identify expression quantitative trait loci (eQTL). However, the conventional eQTL methods usually disregard the systematical role of single-nucleotide polymorphisms (SNPs) or genes, thereby overlooking many network-associated phenotypic determinates. Such a problem motivates us to recognize the network-based quantitative trait loci (QTL), i.e., network QTL (nQTL), which is to detect the cascade association as genotype → network → phenotype rather than conventional genotype → expression → phenotype in eQTL. Specifically, we develop the nQTL framework on the theory and approach of single-sample networks, which can identify not only network traits (e.g., the gene subnetwork associated with genotype) for analyzing complex biological processes but also network signatures (e.g., the interactive gene biomarker candidates screened from network traits) for characterizing targeted phenotype and corresponding subtypes. Our results show that the nQTL framework can efficiently capture associations between SNPs and network traits (i.e., edge traits) in various simulated data scenarios, compared with traditional eQTL methods. Furthermore, we have carried out nQTL analysis on diverse biological and biomedical datasets. Our analysis is effective in detecting network traits for various biological problems and can discover many network signatures for discriminating phenotypes, which can help interpret the influence of nQTL on disease subtyping, disease prognosis, drug response, and pathogen factor association. Particularly, in contrast to the conventional approaches, the nQTL framework could also identify many network traits from human bulk expression data, validated by matched single-cell RNA-seq data in an independent or unsupervised manner. All these results strongly support that nQTL and its detection framework can simultaneously explore the global genotype–network–phenotype associations and the underlying network traits or network signatures with functional impact and importance.

Polycaprolactone Electrospun Scaffolds Produce an Enrichment of Lung Cancer Stem Cells in Sensitive and Resistant EGFRm Lung Adenocarcinoma

Simple Summary

The culture of lung cancer stem cells (LCSCs) is not possible using traditional flat polystyrene surfaces. The study of these tumor-initiating cells is fundamental due to their key role in the resistance to anticancer therapies, tumor recurrence, and metastasis. Hence, we evaluated the use of polycaprolactone electrospun (PCL-ES) scaffolds for culturing LCSC population in sensitive and resistant EGFR-mutated lung adenocarcinoma models. Our findings revealed that both cell models seeded on PCL-ES structures showed a higher drug resistance, enhanced levels of several genes and proteins related to epithelial-to-mesenchymal process, stemness, and surface markers, and the activation of the Hedgehog pathway. We also determined that the non-expression of CD133 was associated with a low degree of histological differentiation, disease progression, distant metastasis, and worse overall survival in EGFR-mutated non-small cell lung cancer patients. Therefore, we confirmed PCL-ES scaffolds as a suitable three-dimensional cell culture model for the study of LCSC niche.

Abstract

The establishment of a three-dimensional (3D) cell culture model for lung cancer stem cells (LCSCs) is needed because the study of these stem cells is unable to be done using flat surfaces. The study of LCSCs is fundamental due to their key role in drug resistance, tumor recurrence, and metastasis. Hence, the purpose of this work is the evaluation of polycaprolactone electrospun (PCL-ES) scaffolds for culturing LCSCs in sensitive and resistant EGFR-mutated (EGFRm) lung adenocarcinoma cell models. We performed a thermal, physical, and biological characterization of 10% and 15%-PCL-ES structures. Several genes and proteins associated with LCSC features were analyzed by RT-qPCR and Western blot. Vimentin and CD133 tumor expression were evaluated in samples from 36 patients with EGFRm non-small cell lung cancer through immunohistochemistry. Our findings revealed that PC9 and PC9-GR3 models cultured on PCL-ES scaffolds showed higher resistance to osimertinib, upregulation of ABCB1, Vimentin, Snail, Twist, Sox2, Oct-4, and CD166, downregulation of E-cadherin and CD133, and the activation of Hedgehog pathway. Additionally, we determined that the non-expression of CD133 was significantly associated with a low degree of histological differentiation, disease progression, and distant metastasis. To sum up, we confirmed PCL-ES scaffolds as a suitable 3D cell culture model for the study of the LCSC niche.

Identification of Novel Biomarkers Related to Lung Squamous Cell Carcinoma Using Integrated Bioinformatics Analysis

BACKGROUND

Lung squamous cell carcinoma (LUSC) is one of the most common types of lung carcinoma and has specific clinicopathologic characteristics. In this study, we screened novel molecular biomarkers relevant to the prognosis of LUSC to explore new diagnostic and treatment approaches for this disease.

METHODS

We downloaded GSE73402 from the Gene Expression Omnibus (GEO) database. GSE73402 contains 62 samples, which could be classified as four subtypes according to their pathology and stages. Via weighted gene coexpression network analysis (WGCNA), the main module was identified and was further analyzed using differentially expressed genes (DEGs) analysis. Then, by protein-protein interaction (PPI) network and Gene Expression Profiling Interactive Analysis (GEPIA), hub genes were screened for potential biomarkers of LUSC.

RESULTS

Via WGCNA, the yellow module containing 349 genes was identified, and it is strongly related to the subtype of CIS (carcinoma in situ). DEGs analysis detected 180 genes that expressed differentially between the subtype of CIS and subtype of early-stage carcinoma (Stage I and Stage II). A PPI network of DEGs was constructed, and the top 20 genes with the highest correlations were selected for GEPIA database to explore their effect on LUSC survival prognosis. Finally, ITGA5, TUBB3, SCNN1B, and SERPINE1 were screened as hub genes in LUSC.

CONCLUSIONS

ITGA5, TUBB3, SCNN1B, and SERPINE1 may have great diagnostic and prognostic significance for LUSC and have great potential to be new treatment targets for LUSC.

Prospective Clinical Study of Postoperative Individualized Adjuvant Chemotherapy for Patients with Non-Small-Cell Lung Cancer Based on mRNA Expression of the Molecular Markers RRM1, TUBB3, and ERCC1

Objective

To investigate the clinical significance of the mRNA expression of RRM1, TUBB3, and ERCC1 in non-small-cell lung cancer (NSCLC) tissues for the selection of adjuvant/postoperative chemotherapy regimens.

Methods

Patients diagnosed with stage Ib-IIIa NSCLC were enrolled and randomly divided into a control group (undetected group) and an experimental group (detected group) after radical operation. The control group randomly received chemotherapy with gemcitabine plus cisplatin or paclitaxel plus cisplatin. The mRNA expression of RRM1, TUBB3, and ERCC1 was detected in the experimental group before chemotherapy, and based on the detected expression, the chemotherapy regimen of cisplatin plus gemcitabine or cisplatin plus paclitaxel was chosen. The disease-free survival (DFS) of the control group and experimental group was compared.

Results

Pathological type, stage, gene expression detection, and treatment method were not significantly correlated with DFS (P > 0.05). In the subgroups treated with gemcitabine, the median DFS was 17 months in the detected group and 10.5 months in the undetected group (hazard ratio = 0.2147, 95% confidence interval: 0.07909–0.5827, P=0.0025). Multivariate regression analysis was performed to analyse whether gene expression detection was independently correlated with DFS in the subgroups treated with gemcitabine (P=0.025). In the detected group, the prognosis of patients with low expression of RRM1 was better than that of patients with high expression of RRM1 after paclitaxel treatment (P=0.0039).

Conclusions

The selection of chemotherapy regimen based on mRNA expression of the RRM1, TUBB3, and ERCC1 genes may improve selection of candidate patients to receive clinical chemotherapy. However, large-scale prospective clinical studies are needed for in-depth investigation.

βIII-tubulin overexpression in cancer: Causes, consequences, and potential therapies

Class III β-tubulin (βIII-tubulin) is frequently overexpressed in human tumors and is associated with resistance to microtubule-targeting agents, tumor aggressiveness, and poor patient outcome. Understanding the mechanisms regulating βIII-tubulin expression and the varied functions βIII-tubulin may have in different cancers is vital to assess the prognostic value of this protein and to develop strategies to enhance therapeutic benefits in βIII-tubulin overexpressing tumors. Here we gather all the available evidence regarding the clinical implications of βIII-tubulin overexpression in cancer, describe factors that regulate βIII-tubulin expression, and discuss current understanding of the mechanisms underlying βIII-tubulin-mediated resistance to microtubule-targeting agents and tumor aggressiveness. Finally, we provide an overview of emerging therapeutic strategies to target tumors that overexpress βIII-tubulin.

TUBB3 is associated with PTEN, neuroendocrine differentiation, and castration resistance in prostate cancer

BACKGROUND

Tubulin-β3 encoded by the Tubulin-β3 (TUBB3) gene is a microtubule protein. Previous studies have shown that TUBB3 expression is upregulated in castration-resistant prostate cancer (CaP) and is involved in taxane resistance. However, the biological mechanism of TUBB3 involvement in the progression to castration-resistant CaP is not fully elucidated. This study aimed to analyze the expression and function of TUBB3 in localized and metastatic CaP.

METHODS

TUBB3 expression was determined using immunohistochemistry in localized and metastatic CaP. We also investigated the association between TUBB3, phosphatase and tensin homolog (PTEN), and neuroendocrine differentiation and examined the involvement of TUBB3 in new antiandrogen drugs (enzalutamide and apalutamide) resistance in metastatic CaP.

RESULTS

In 155 cases of localized CaP, immunohistochemistry showed that 5 (3.2%) of the CaP cases were positive for tubulin-β3. Kaplan-Meier analysis showed that high expression of tubulin-β3 was associated with poor prostate-specific antigen recurrence-free survival after radical prostatectomy. In 57 cases of metastatic CaP, immunohistochemistry showed that 14 (25%) cases were positive for tubulin-β3. Tubulin-β3 expression was higher in metastatic CaP than in localized CaP. High tubulin-β3 expression was correlated with negative PTEN expression. TUBB3 expression was increased in neuroendocrine CaP based on several public databases. PTEN knockout decreased the sensitivity to enzalutamide and apalutamide in 22Rv-1 cells. TUBB3 knockdown reversed the sensitivity to enzalutamide and apalutamide in PTEN-CRISPR 22Rv-1 cells. High expression of tubulin-β3 and negative expression of PTEN were significantly associated with poor overall survival in metastatic CaP treated with androgen deprivation therapy.

CONCLUSIONS

These results suggest that TUBB3 may be a useful predictive biomarker for survival and play an essential role in antiandrogen resistance in CaP.

Therapeutic strategies to overcome taxane resistance in cancer

One of the primary causes of attenuated or loss of efficacy of cancer chemotherapy is the emergence of multidrug resistance (MDR). Numerous studies have been published regarding potential approaches to reverse resistance to taxanes, including paclitaxel (PTX) and docetaxel, which represent one of the most important classes of anticancer drugs. Since 1984, following the FDA approval of paclitaxel for the treatment of advanced ovarian carcinoma, taxanes have been extensively used as drugs that target tumor microtubules. Taxanes, have been shown to affect an array of oncogenic signaling pathways and have potent cytotoxic efficacy. However, the clinical success of these drugs has been restricted by the emergence of cancer cell resistance, primarily caused by the overexpression of MDR efflux transporters or by microtubule alterations. In vitro and in vivo studies indicate that the mechanisms underlying the resistance to PTX and docetaxel are primarily due to alterations in α-tubulin and β-tubulin. Moreover, resistance to PTX and docetaxel results from: 1) alterations in microtubule-protein interactions, including microtubule-associated protein 4, stathmin, centriole, cilia, spindle-associated protein, and kinesins; 2) alterations in the expression and activity of multidrug efflux transporters of the ABC superfamily including P-glycoprotein (P-gp/ABCB1); 3) overexpression of anti-apoptotic proteins or inhibition of apoptotic proteins and tumor-suppressor proteins, as well as 4) modulation of signal transduction pathways associated with the activity of several cytokines, chemokines and transcription factors. In this review, we discuss the abovementioned molecular mechanisms and their role in mediating cancer chemoresistance to PTX and docetaxel. We provide a detailed analysis of both in vitro and in vivo experimental data and describe the application of these findings to therapeutic practice. The current review also discusses the efficacy of different pharmacological modulations to achieve reversal of PTX resistance. The therapeutic roles of several novel compounds, as well as herbal formulations, are also discussed. Among them, many structural derivatives had efficacy against the MDR phenotype by either suppressing MDR or increasing the cytotoxic efficacy compared to the parental drugs, or both. Natural products functioning as MDR chemosensitizers offer novel treatment strategies in patients with chemoresistant cancers by attenuating MDR and increasing chemotherapy efficacy. We broadly discuss the roles of inhibitors of P-gp and other efflux pumps, in the reversal of PTX and docetaxel resistance in cancer cells and the significance of using a nanomedicine delivery system in this context. Thus, a better understanding of the molecular mechanisms mediating the reversal of drug resistance, combined with drug efficacy and the application of target-based inhibition or specific drug delivery, could signal a new era in modern medicine that would limit the pathological consequences of MDR in cancer patients.

Expression of Class III Beta-Tubulin Is Associated with Invasive Potential and Poor Prognosis in Thyroid Carcinoma

Although American Thyroid Association guidelines offer a risk stratification scheme for thyroid cancer patients, there is a continuous need for more sophisticated biomarkers that can predict disease progression. In this study, we aim to evaluate the prognostic value of class III beta-tubulin (TUBB3) and uncover the relationship between TUBB3 and invasive potential in thyroid carcinoma. Immunohistochemistry (IHC) for TUBB3 and E-cadherin was performed on a total of 254 cases of thyroid cancer specimens. Tumor budding at the invasive margin was evaluated. In vitro functional studies were also performed; the protein and mRNA levels of TUBB3 were compared among the five cell types at baseline, with transwell invasion and after blocking of TUBB3 by shRNA. IHC revealed that the levels of TUBB3 were higher in conventional papillary carcinomas (cPTCs) and anaplastic thyroid carcinomas (ATCs). In univariate analysis, high tumor budding and TUBB3 expression were associated with inferior progression-free survival in cPTC. The results of a Western blot and RT-PCR agreed with the IHC finding. The results were further validated through data from The Cancer Genome Atlas database. Our results suggest that high expression of TUBB3 in thyroid carcinoma could predict invasive potential and possibly be linked with epithelial–mesenchymal transition.

Intrinsic and Extrinsic Factors Affecting Microtubule Dynamics in Normal and Cancer Cells

Microtubules (MTs), highly dynamic structures composed of α- and β-tubulin heterodimers, are involved in cell movement and intracellular traffic and are essential for cell division. Within the cell, MTs are not uniform as they can be composed of different tubulin isotypes that are post-translationally modified and interact with different microtubule-associated proteins (MAPs). These diverse intrinsic factors influence the dynamics of MTs. Extrinsic factors such as microtubule-targeting agents (MTAs) can also affect MT dynamics. MTAs can be divided into two main categories: microtubule-stabilizing agents (MSAs) and microtubule-destabilizing agents (MDAs). Thus, the MT skeleton is an important target for anticancer therapy. This review discusses factors that determine the microtubule dynamics in normal and cancer cells and describes microtubule–MTA interactions, highlighting the importance of tubulin isoform diversity and post-translational modifications in MTA responses and the consequences of such a phenomenon, including drug resistance development.

TUBB3 Is Associated with High-Grade Histology, Poor Prognosis, p53 Expression, and Cancer Stem Cell Markers in Clear Cell Renal Cell Carcinoma

BACKGROUND

βIII-Tubulin, encoded by the TUBB3 gene, is a microtubule protein. Several studies have shown that overexpression of TUBB3 is linked to poor prognosis and is involved in taxane resistance in some cancers.

OBJECTIVE

The aim of this study was to analyze the expression and function of TUBB3 in clear cell renal cell carcinoma (ccRCC).

METHODS

The expression of TUBB3 was determined using immuno-histochemistry in ccRCC specimens. The effects of TUBB3 knockdown on cell growth and invasion were evaluated in RCC cell lines. We analyzed the interaction between TUBB3, p53, cancer stem cell markers, and PD-L1.

RESULTS

In 137 cases of ccRCC, immunohistochemistry showed that 28 (20%) of the ccRCC cases were positive for TUBB3. High TUBB3 expression was significantly correlated with high nuclear grade, high T stage, and N stage. A Kaplan-Meier analysis showed that high expression of TUBB3 was associated with poor overall survival after nephrectomy. In silico analysis also showed that high TUBB3 expression was correlated with overall survival. Knockdown of TUBB3 suppressed cell growth and invasion in 786-O and Caki-1 cells. High TUBB3 expression was associated with CD44, CD133, PD-L1, and p53 in ccRCC. We generated p53 knockout cells using the CRISPR-Cas9 system. Western blotting revealed that p53 knockout upregulated the expression of TUBB3.

CONCLUSION

These results suggest that TUBB3 may play an oncogenic role and could be a potential therapeutic target in ccRCC.

Role of the YAP-1 Transcriptional Target cIAP2 in the Differential Susceptibility to Chemotherapy of Non-Small-Cell Lung Cancer (NSCLC) Patients with Tumor RASSF1A Gene Methylation from the Phase 3 IFCT-0002 Trial

RASSF1 gene methylation predicts longer disease-free survival (DFS) and overall survival (OS) in patients with early-stage non-small-cell lung cancer treated using paclitaxel-based neo-adjuvant chemotherapy compared to patients receiving a gemcitabine-based regimen, according to the randomized Phase 3 IFCT (Intergroupe Francophone de Cancérologie Thoracique)-0002 trial. To better understand these results, this study used four human bronchial epithelial cell (HBEC) models (HBEC-3, HBEC-3-RasV12, A549, and H1299) and modulated the expression of RASSF1A or YAP-1. Wound-healing, invasion, proliferation and apoptosis assays were then carried out and the expression of YAP-1 transcriptional targets was quantified using a quantitative polymerase chain reaction. This study reports herein that gemcitabine synergizes with RASSF1A, silencing to increase the IAP-2 expression, which in turn not only interferes with cell proliferation but also promotes cell migration. This contributes to the aggressive behavior of RASSF1A-depleted cells, as confirmed by a combined knockdown of IAP-2 and RASSF1A. Conversely, paclitaxel does not increase the IAP-2 expression but limits the invasiveness of RASSF1A-depleted cells, presumably by rescuing microtubule stabilization. Overall, these data provide a functional insight that supports the prognostic value of RASSF1 gene methylation on survival of early-stage lung cancer patients receiving perioperative paclitaxel-based treatment compared to gemcitabine-based treatment, identifying IAP-2 as a novel biomarker indicative of YAP-1-mediated modulation of chemo-sensitivity in lung cancer.

TUBB3 Reverses Resistance to Docetaxel and Cabazitaxel in Prostate Cancer

Recent studies have reported that TUBB3 overexpression is involved in docetaxel (DTX) resistance in prostate cancer (PCa). The aim of this study was to clarify the role of TUBB3 in DTX and cabazitaxel (CBZ) resistance, and cross-resistance between DTX and CBZ in PCa. We analyzed the effect of TUBB3 knockdown on DTX and CBZ resistance and examined the interaction between TUBB3 and PTEN. We also investigated the role of phosphoinositide 3-kinases (PI3K) inhibitor (LY294002) in DTX and CBZ resistance. TUBB3 expression was upregulated in DTX-resistant and CBZ-resistant cells. TUBB3 knockdown re-sensitized DTX-resistant cells to DTX and CBZ-resistant cells to CBZ. Additionally, TUBB3 knockdown re-sensitized DTX-resistant cell lines to CBZ, indicating that TUBB3 mediates cross-resistance between DTX and CBZ. Knockdown of TUBB3 enhanced PTEN expression, and PTEN knockout enhanced TUBB3 expression. LY294002 suppressed TUBB3 expression in DTX-resistant and CBZ-resistant cell lines. LY294002 re-sensitized DTX-resistant cell lines to DTX and CBZ-resistant cell lines to CBZ. These results suggest that TUBB3 is involved in DTX resistance and CBZ resistance. A combination of LY294002/DTX and that of LY294002/CBZ could be potential strategies for PCa treatment.

TUBB4B Downregulation Is Critical for Increasing Migration of Metastatic Colon Cancer Cells

Tumor metastasis, the major problem for clinical oncology in colon cancer treatment, is linked with an epithelial-mesenchymal transition (EMT). The observed cellular transformation in this process is manifested by cell elongation, enhanced cell migration and invasion ability, coordinated by cytoskeleton reorganization. In the present study, we examined the role of tubulin-β4 (TUBB4B) downregulation that occurs during EMT in colon cancer cells, in the modulation of the function of microtubules. Based on biochemical and behavioral analysis (transmigration) we posit that the decrease of the TUBB4B level is critical for microtubule-vimentin interaction and contributes to the maintenance of polarity in migrating cells. The microscopic studies revealed that TUBB4B decrease is accompanied by cell elongation and increased number of matured focal adhesion sites, which is a characteristic of the cell metastatic stage. We also demonstrated faster polymerization of microtubules in cells with a lower level of TUBB4B. Simultaneous TUBB3 upregulation, reported during EMT, acts additively in this process. Our studies suggest that the protein level of TUBB4B could be used as a marker for detection of the preinvasive stages of the colon cancer cells. We also concluded that chemotherapy enriched to increase TUBB4B level and/or to stabilize microtubule polymerization might more effectively prevent metastasis in colon cancer development.

ALDH1A1 in patient-derived bladder cancer spheroids activates retinoic acid signaling leading to TUBB3 overexpression and tumor progression

Acquired chemoresistance is a critical issue for advanced bladder cancer patients during long-term treatment. Recent studies reveal that a fraction of tumor cells with enhanced tumor-initiating potential, or cancer stem-like cells (CSCs), may particularly contribute to acquired chemoresistance and recurrence. Thus, CSC characterization will be the first step towards understanding the mechanisms underlying advanced disease. Here we generated long-term patient-derived cancer cells (PDCs) from bladder cancer patient specimens in spheroid culture, which is favorable for CSC enrichment. Pathological features of bladder cancer PDCs and PDC-dependent patient-derived xenografts (PDXs) were basically similar to those of their corresponding patients' specimens. Notably, CSC marker aldehyde dehydrogenase 1A1 (ALDH1A1), a critical enzyme that synthesizes retinoic acid (RA), was abundantly expressed in PDCs. ALDH1A1 inhibitors and shRNAs repressed both PDC proliferation and spheroid formation, whereas all-trans RA could rescue ALDH1A1 shRNA-suppressed spheroid formation. ALDH inhibitor also reduced the in vivo growth of PDC-derived xenografts. ALDH1A1 knockdown study showed that tubulin beta III (TUBB3) was one of the downregulated genes in PDCs. We identified functional RA response elements in TUBB3 promoter, whose transcriptional activities were substantially activated by RA. Clinical survival database reveals that TUBB3 expression may associate with poor prognosis in bladder cancer patients. Moreover, TUBB3 knockdown was sufficient to suppress PDC proliferation and spheroid formation. Taken together, our results indicate that ALDH1A1 and its putative downstream target TUBB3 are overexpressed in bladder cancer, and those molecules could be applied to alternative diagnostic and therapeutic options for advanced disease.

Role of HDAC3-miRNA-CAGE Network in Anti-Cancer Drug-Resistance

Histone modification is associated with resistance to anti-cancer drugs. Epigenetic modifications of histones can regulate resistance to anti-cancer drugs. It has been reported that histone deacetylase 3 (HDAC3) regulates responses to anti-cancer drugs, angiogenic potential, and tumorigenic potential of cancer cells in association with cancer-associated genes (CAGE), and in particular, a cancer/testis antigen gene. In this paper, we report the roles of microRNAs that regulate the expression of HDAC3 and CAGE involved in resistance to anti-cancer drugs and associated mechanisms. In this review, roles of HDAC3-miRNAs-CAGE molecular networks in resistance to anti-cancer drugs, and the relevance of HDAC3 as a target for developing anti-cancer drugs are discussed.

Sulforaphane metabolites reduce resistance to paclitaxel via microtubule disruption

Long treatment with paclitaxel (PTX) might increase resistance and side-effects causing a failure in cancer chemotherapy. Here we uncovered that either sulforaphane-cysteine (SFN-Cys) or sulforaphane-N-acetyl-cysteine (SFN-NAC) induced apoptosis via phosphorylated ERK1/2-mediated upregulation of 26 S proteasome and Hsp70, and downregulation of βIII-tubulin, XIAP, Tau, Stathmin1 and α-tubulin causing microtubule disruption in human PTX-resistant non-small cell lung cancer (NSCLC) cells. Knockdown of either βIII-tubulin or α-tubulin via siRNA increased cell sensitivity to PTX, indicating that these two proteins help cells increase the resistance. Tissue microarray analysis showed that overexpression of βIII-tubulin correlated to NSCLC malignant grading. Immunofluorescence staining also showed that SFN metabolites induced a nest-like microtubule protein distribution with aggregation and disruption. Co-immunoprecipitation showed that SFN metabolites reduced the interaction between βIII-tubulin and Tau, and that between α-tubulin and XIAP. The combination of PTX with SFN metabolites decreased the resistance to PTX, and doses of both PTX and SFN metabolites, and enhanced apoptosis resulting from activated Caspase-3-caused microtubule degradation. Importantly, the effective dose of SFN metabolites combined with 20 nM PTX will be low to 4 μM. Thus, we might combine SFN metabolites with PTX for preclinical trial. Normally, more than 20 μM SFN metabolites only leading to apoptosis for SFN metabolites hindered their applications. These findings will help us develop a low-resistance and high-efficiency chemotherapy via PTX/SFN metabolites combination.

High expression of class III β-tubulin in upper gastrointestinal cancer types

Class III β-tubulin (TUBB3) is a component of microtubules of neuronal cells that is upregulated in various cancer entities. To better understand the role of TUBB3 in upper gastrointestinal tract cancer types, the present study assessed TUBB3 expression in tissue microarrays including 189 gastric and 428 esophageal cancer. TUBB3 expression was detected in 62.4% of gastric cancer, 73.8% of esophageal adenocarcinoma and 88.7% of esophageal squamous cell cancer, while control samples of normal esophageal and gastric epithelium were TUBB3-negative. TUBB3 positivity was not associated with the International Union Against Cancer classification, World Health Organization grading, lymph node involvement or distant metastasis in any entity. Of note, TUBB3 expression was associated with tumor localization and prognosis in gastric cancer, with the tumor stage in esophageal adenocarcinoma, and with the resection margin in esophageal squamous cell cancer. In conclusion, the substantial rate of positivity for TUBB3 already in early stages of gastric cancer in combination with the lack of a further increase in frequency with tumor stage, may suggest, that TUBB3 upregulation is rather relevant for cancer development than for cancer progression. TUBB3 might be a suitable prognostic biomarker in gastric cancer types.

MSH2/BRCA1 expression as a DNA-repair signature predicting survival in early-stage lung cancer patients from the IFCT-0002 Phase 3 Trial

Introduction

DNA repair is a double-edged sword in lung carcinogenesis. When defective, it promotes genetic instability and accumulated genetic alterations. Conversely these defects could sensitize cancer cells to therapeutic agents inducing DNA breaks.

Methods

We used immunohistochemistry (IHC) to assess MSH2, XRCC5, and BRCA1 expression in 443 post-chemotherapy specimens from patients randomized in a Phase 3 trial, comparing two neoadjuvant regimens in 528 Stage I-II non-small cell lung cancer (NSCLC) patients (IFCT-0002). O6MGMT promoter gene methylation was analyzed in a subset of 208 patients of the same trial with available snap-frozen specimens.

Results

Median follow-up was from 90 months onwards. Only high BRCA1 (n = 221, hazard ratio [HR] = 1.58, 95% confidence interval [CI] [1.07-2.34], p = 0.02) and low MSH2 expression (n = 356, HR = 1.52, 95% CI [1.11-2.08], p = 0.008) significantly predicted better overall survival (OS) in univariate and multivariate analysis. A bootstrap re-sampling strategy distinguished three patient groups at high (n = 55, low BRCA1 and high MSH2, median OS >96 months, HR = 2.5, 95% CI [1.45-4.33], p = 0.001), intermediate (n = 82, median OS = 73.4 p = 0.0596), and low (high BRCA1 and low MSH2, n = 67, median OS = ND, HR = 0.51, 95% CI [0.31-0.83], p = 0.006) risk of death.

Interpretation

DNA repair protein expression assessment identified three different groups of risk of death in early-stage lung cancer patients, according to their tumor MSH2 and BRCA1 expression levels. These results deserve prospective evaluation of MSH2/BRCA1 theranostic value in lung cancer patients treated with combinations of DNA-damaging chemotherapy and drugs targeting DNA repair, such as Poly(ADP-ribose) polymerase (PARP) inhibitors.

Prevalence of βIII-tubulin (TUBB3) expression in human normal tissues and cancers

Microtubules are multifunctional cytoskeletal proteins that are involved in crucial cellular roles including maintenance of cell shape, intracellular transport, meiosis, and mitosis. Class III beta-tubulin (βIII-tubulin, also known as TUBB3) is a microtubule protein, normally expressed in cells of neuronal origin. Its expression was also reported in various other tumor types, such as several types of lung cancer, ovarian cancer, and esophageal cancer. TUBB3 is of clinical relevance as overexpression has been linked to poor response to microtubule-targeting anti-cancer drugs such as taxanes. To systematically investigate the epidemiology of TUBB3 expression in normal and neoplastic tissues, we used tissue microarrays for analyzing the immunohistochemically detectable expression of TUBB3 in 3911 tissue samples from 100 different tumor categories and 76 different normal tissue types. At least 1 tumor with weak expression could be found in 93 of 100 (93%) different tumor types, and all these 93 entities also had at least 1 tumor with strong positivity. In normal tissues, a particularly strong expression was found in neurons of the brain, endothelium of blood vessels, fibroblasts, spermatogenic cells, stroma cells, endocrine cells, and acidophilic cells of the pituitary gland. In tumors, strong TUBB3 expression was most frequently found in various brain tumors (85%-100%), lung cancer (35%-80%), pancreatic adenocarcinoma (50%), renal cell carcinoma (15%-80%), and malignant melanoma (77%). In summary, these results identify a broad spectrum of cancers that can at least sporadically express TUBB3. Testing of TUBB3 in cancer types eligible for taxane-based therapies could be helpful to identify patients who might best benefit from this treatment.

Prognostic effect of class III β-tubulin and Topoisomerase-II in patients with advanced thymic carcinoma who received combination chemotherapy, including taxanes or topoisomerase-II inhibitors

Class III β-tubulin (TUBB3) and Topoisomerase-II (topo-II) are considered to be the predictors of therapeutic efficacy and outcome in several types of human neoplasm. However, whether TUBB3 or topo-II may predict the response to combination chemotherapy and prognosis in patients with advanced thymic carcinoma (ATC) remains unclear. The aim of the present study was to investigate the prognostic significance of TUBB3 and topo-II expression levels in ATC. A total of 34 patients with ATC who received combination chemotherapy were enrolled in the present study. Immunohistochemical analysis was used to examine the expression of TUBB3, topo-II and Ki-67 in tumor specimens obtained by surgical resection or biopsy. TUBB3 and topo-II were highly expressed in 38 and 53% of the tumors, respectively. Progression-free survival (PFS) was significantly shorter in patients with high levels of TUBB3 compared with those with low levels of TUBB3 (P<0.01), whereas no significant difference in PFS between patients with high and low topo-II expression levels was observed (P=0.31). Patients with overexpression of TUBB3 or topo-II exhibited significantly shorter overall survival rates (OS) compared with those patients with low levels of expression of these proteins (TUBB3; P=0.01, topo-II; P=0.01). Multivariate analysis demonstrated that a high level of TUBB3 expression was an independent unfavorable prognostic factor for OS, and a high level of topo-II expression tended to correlate with poor prognosis without statistical significance. Additionally, a subset analysis demonstrated that the treatment with taxanes, but not topo-II inhibitors, tended to prolong OS in patients with TUBB3 overexpression and there was significant survival advantage of chemoradiotherapy over chemotherapy in patients with topo-II overexpression. It was revealed that an enhanced expression of TUBB3 or topo-II was clearly associated with clinical outcomes in patients with ATC who received combination chemotherapy, including taxanes or topo-II inhibitors, suggesting the prognostic significance of these markers.

[Current knowledge on perioperative treatments of non-small cell lung carcinomas]

Surgery is still the main treatment in early-stage of non-small cell lung cancer with 5-year survival of stage IA patients exceeding 80%, but 5-year survival of stage II patients rapidly decreasing with tumor size, N status, and visceral pleura invasion. The major metastatic risk in such patients has supported clinical research assessing systemic or loco-regional perioperative treatments. Modern phase 3 trials clearly validated adjuvant or neo-adjuvant platinum-based chemotherapy in resected stage I-III patients as a standard treatment of which value has been reassessed several independent meta-analyses, showing a 5% benefit in 5y-survival, and a decrease of the relative risk for death around from 12 to 25%. Conversely perioperative treatments were not validated for stage IA and IB patients. In more advanced stage patients, neo-adjuvant radio-chemotherapy has not been validated either. Adjuvant radiotherapy for N2 patients is currently tested in the large international phase 3 trial Lung-ART/IFCT-0503. The development of video-assisted thoracic surgery (VATS) has helped adjuvant chemotherapies for elderly patients. Perioperative targeted treatments in NSCLC with EGFR or ALK molecular alterations is currently assessed in the U.S. ALCHEMIST prospective trial. Finally, the role of immune check-points inhibitors is currently evaluated in a large international phase 3 trial testing adjuvant anti-PD-L1 monoclonal antibody, the BR31/IFCT-1401 trial, while a proof-of principle neo-adjuvant trial IONESCO/IFCT-1601, has just begun by the end of the 2016 year, with survival results of both trials expected in 5 to 7 years.

An Emerging Role for Tubulin Isotypes in Modulating Cancer Biology and Chemotherapy Resistance

Tubulin proteins, as components of the microtubule cytoskeleton perform critical cellular functions throughout all phases of the cell cycle. Altered tubulin isotype composition of microtubules is emerging as a feature of aggressive and treatment refractory cancers. Emerging evidence highlighting a role for tubulin isotypes in differentially influencing microtubule behaviour and broader functional networks within cells is illuminating a complex role for tubulin isotypes regulating cancer biology and chemotherapy resistance. This review focuses on the role of different tubulin isotypes in microtubule dynamics as well as in oncogenic changes that provide a survival or proliferative advantage to cancer cells within the tumour microenvironment and during metastatic processes. Consideration of the role of tubulin isotypes beyond their structural function will be essential to improving the current clinical use of tubulin-targeted chemotherapy agents and informing the development of more effective cancer therapies.

Tubulin Beta-3 Chain as a New Candidate Protein Biomarker of Human Skin Aging: A Preliminary Study

Skin aging is a complex process, and a lot of efforts have been made to identify new and specific targets that could help to diagnose, prevent, and treat skin aging. Several studies concerning skin aging have analyzed the changes in gene expression, and very few investigations have been performed at the protein level. Moreover, none of these proteomic studies has used a global quantitative labeled proteomic offgel approach that allows a more accurate description of aging phenotype. We applied such an approach on human primary keratinocytes obtained from sun-nonexposed skin biopsies of young and elderly women. A total of 517 unique proteins were identified, and 58 proteins were significantly differentially expressed with 40 that were downregulated and 18 upregulated with aging. Gene ontology and pathway analysis performed on these 58 putative biomarkers of skin aging evidenced that these dysregulated proteins were mostly involved in metabolism and cellular processes such as cell cycle and signaling pathways. Change of expression of tubulin beta-3 chain was confirmed by western blot on samples originated from several donors. Thus, this study suggested the tubulin beta-3 chain has a promising biomarker in skin aging.

Novel mutations involving βI-, βIIA-, or βIVB-tubulin isotypes with functional resemblance to βIII-tubulin in breast cancer

Tubulin is the target for very widely used anti-tumor drugs, including Vinca alkaloids, taxanes, and epothilones, which are an important component of chemotherapy in breast cancer and other malignancies. Paclitaxel and other tubulin-targeting drugs bind to the β subunit of tubulin, which is a heterodimer of α and β subunits. β-Tubulin exists in the form of multiple isotypes, which are differentially expressed in normal and neoplastic cells and differ in their ability to bind to drugs. Among them, the βIII isotype is overexpressed in many aggressive and metastatic cancers and may serve as a prognostic marker in certain types of cancer. The underpinning mechanisms accounting for the overexpression of this isotype in cancer cells are unclear. To better understand the role of β-tubulin isotypes in cancer, we analyzed over 1000 clones from 90 breast cancer patients, sequencing their β-tubulin isotypes, in search of novel mutations. We have elucidated two putative emerging molecular subgroups of invasive breast cancer, each of which involve mutations in the βI-, βIIA-, or βIVB isotypes of tubulin that increase their structural, and possibly functional, resemblance to the βIII isotype. A unifying feature of the first of the two subgroups is the mutation of the highly reactive C239 residue of βI- or βIVB-tubulin to L239, R239, Y239, or P239, culminating in probable conversion of these isotypes from ROS-sensitive to ROS-resistant species. In the second subgroup, βI, βIIA, and βIVB have up to seven mutations to the corresponding residues in βIII-tubulin. Given that βIII-tubulin has emerged as a pro-survival factor, overexpression of this isotype may confer survival advantages to certain cancer cell types. In this mini-review, we bring attention to a novel mechanism by which cancer cells may undergo adaptive mutational changes involving alternate β-tubulin isotypes to make them acquire some of the pro-survival properties of βIII-tubulin. These "hybrid" tubulins, combining the sequences and/or properties of two wild-type tubulins (βIII and either βI, βIIA, or βIVB), are novel isotypes expressed solely in cancer cells and may contribute to the molecular understanding and stratification of invasive breast cancer and provide novel molecular targets for rational drug development.

Evaluation of tubulin β-3 as a novel senescence-associated gene in melanocytic malignant transformation

Malignant melanoma might develop from melanocytic nevi in which the growth-arrested state has been broken. We analyzed the gene expression of young and senescent human melanocytes in culture and compared the gene expression data with a dataset from nevi and melanomas. A concordant altered gene expression was identified in 84 genes when comparing the growth-arrested samples with proliferating samples. TUBB3, which encodes the microtubule protein tubulin β-3, showed a decreased expression in senescent melanocytes and nevi and was selected for further studies. Depletion of tubulin β-3 caused accumulation of cells in the G2/M phase and decreased proliferation and migration. Immunohistochemical assessment of tubulin β-3 in benign lesions revealed strong staining in the superficial part of the intradermal components, which faded with depth. In contrast, primary melanomas exhibited staining without gradient in a disordered pattern and strong staining of the invasive front. Our results describe an approach to find clinically useful diagnostic biomarkers to more precisely identify cutaneous malignant melanoma and present tubulin β-3 as a candidate marker.

[Perioperative therapies in surgical non N2 non-small cell lung cancer]

Platinum-based perioperative chemotherapy is actually the standard of care in stage II-IIIa non-small cell lung cancer (NSCLC). A benefit may also be seen in stage IB NSCLC with tumors of more than 4cm of diameter. Perioperative chemotherapy improves 5-year survival of 4 to 15%. This benefit is mainly proved by postoperative chemotherapy trials. Nevertheless, preoperative chemotherapy has advantages: a better tolerance, an estimation of tumor chemosensibility, without an increased postoperative morbimortality. However, pTNM and pathological tumor analyses are modified. Indications of postoperative radiotherapy are limited. In early stage NSCLC (stage I-II), radiotherapy worsens survival. Radiotherapy is routinely achieved in NSCLC with parietal tumor invasion and incomplete tumor resection. Indications of immunotherapy and targeted therapies in case of oncogenic addiction remain to be established in resected NSCLC. Several biomarkers are studied to better describe the indications of perioperative chemotherapy: recognize groups of patients with a worse prognosis and distinguish chemosensibility of the tumor.

Class III β-Tubulin in Colorectal Cancer: Tissue Distribution and Clinical Analysis of Chinese Patients

BACKGROUND Class III β-tubulin (βIII-tubulin) has been reported to express at the invasive margin of colorectal cancer. The present study aimed to investigate the clinical implication of βIII-tubulin expression at the invasive margin of colorectal cancer. MATERIAL AND METHODS We recruited 111 patients with surgically resected colorectal carcinoma for bIII-tubulin expression analysis. The cases with bIII-tubulin-positive tumor cells found only in the invasive front tumor area were assigned to the invasive front group, while the remaining cases were all assigned to the non-invasive front group. Clinical analysis of βIII-tubulin and other clinical data was performed. RESULTS The positive staining rates and staining intensity of bIII-tubulin were significantly different between the invasive and non-invasive front groups (p=0.001 and p=0.006), and there was a significant difference in tumor differentiation between the 2 groups (p=0.032). In the non-invasive front group, staining intensity of bIII-tubulin was significantly associated with positive staining rates and lymphatic metastasis (p<0.001 and p=0.048). CONCLUSIONS Our data showed the tissue distribution of bIII-tubulin expression at invasive margin or diffuse distribution. Expression of bIII-tubulin was correlated with tumor differentiation and lymphatic metastasis, suggesting a potential role of bIII-tubulin in tumor differentiation and metastasis. This study may shed light on bIII-tubulin as a novel potential molecular target for a new anti-cancer drug.

RASSF1A Suppresses the Invasion and Metastatic Potential of Human Non-Small Cell Lung Cancer Cells by Inhibiting YAP Activation through the GEF-H1/RhoB Pathway

Inactivation of the tumor suppressor gene RASSF1A by promoter hypermethylation represents a key event underlying the initiation and progression of lung cancer. RASSF1A inactivation is also associated with poor prognosis and may promote metastatic spread. In this study, we investigated how RASSF1A inactivation conferred invasive phenotypes to human bronchial cells. RNAi-mediated silencing of RASSF1A induced epithelial-to-mesenchymal transition (EMT), fomenting a motile and invasive cellular phenotype in vitro and increased metastatic prowess in vivo. Mechanistic investigations revealed that RASSF1A blocked tumor growth by stimulating cofilin/PP2A-mediated dephosphorylation of the guanine nucleotide exchange factor GEF-H1, thereby stimulating its ability to activate the antimetastatic small GTPase RhoB. Furthermore, RASSF1A reduced nuclear accumulation of the Hippo pathway transcriptional cofactor Yes-associated protein (YAP), which was reinforced by RhoB activation. Collectively, our results indicated that RASSF1 acts to restrict EMT and invasion by indirectly controlling YAP nuclear shuttling and activation through a RhoB-regulated cytoskeletal remodeling process, with potential implications to delay the progression of RASSF1-hypermethylated lung tumors.

Biomarkers for efficacy of adjuvant chemotherapy following complete resection in NSCLC stages I-IIIA

Biomarkers may be useful when deciding which nonsmall cell lung cancer (NSCLC) patients may benefit from adjuvant chemotherapy following complete resection and which chemotherapeutic agents may be used preferably in individual patients in order to maximise survival.

A literature search covering the period from 2003 to May, 2014 was conducted using PubMed and the following search terms: “non-small cell lung cancer”, “NSCLC”, “adjuvant chemotherapy”, “randomized”, “randomised”, “biomarkers”, “prognostic”, “predictive”. This review focuses on current knowledge of biomarkers for prognosis or efficacy of adjuvant treatment following complete resection in stage I–IIIA NSCLC patients.

This review includes results on 18 different biomarkers and five gene profiles. A statistically significant prognostic impact was reported for: iNTR, TUBB3, RRM1, ERCC1, BRCA1, p53, MRP2, MSH2, TS, mucin, BAG-1, pERK1/2, pAkt-1, microRNA, TopIIA, 15-gene profile, 92-gene profile, 31-gene profile and 14-gene profile. A statistically significant predictive impact was reported for: ERCC1, p53, MSH2, p27, TUBB3, PARP1, ATM, 37-gene profile, 31-gene profile, 15-gene profile and 92-gene profile.

Uncertainties regarding the optimal analysis method and cut-off levels for the individual markers may blur the prognostic or predictive signals. None of the possible predictive markers have been validated in prospective trials. Thus, there are no biomarkers ready to use in an adjuvant setting in NSCLC.

Further investigation and validation is required to explore biomarkers in completely resected NSCLC stage I–IIIAhttp://ow.ly/M0leE

Tumor suppressor genes and their underlying interactions in paclitaxel resistance in cancer therapy

Objectives

Paclitaxel (PTX) is frequently used in the clinical treatment of solid tumors. But the PTX-resistance is a great obstacle in cancer treatment. Exploration of the mechanisms of drug resistance suggests that tumor suppressor genes (TSGs) play a key role in the response of chemotherapeutic drugs. TSGs, a set of genes that are often inactivated in cancers, can regulate various biological processes. In this study, an overview of the contribution of TSGs to PTX resistance and their underlying relationship in cancers are reported by using GeneMANIA, a web-based tool for gene/protein function prediction.

Methods

Using PubMed online database and Google web site, the terms “paclitaxel resistance” or “taxol resistance” or “drug resistance” or “chemotherapy resistance”, and “cancer” or “carcinoma”, and “tumor suppressor genes” or “TSGs” or “negative regulated protein” or “antioncogenes” were searched and analyzed. GeneMANIA data base was used to predict gene/protein interactions and functions.

Results

We identified 22 TSGs involved in PTX resistance, including BRCA1, TP53, PTEN, APC, CDKN1A, CDKN2A, HIN-1, RASSF1, YAP, ING4, PLK2, FBW7, BLU, LZTS1, REST, FADD, PDCD4, TGFBI, ING1, Bax, PinX1 and hEx. The TSGs were found to have direct and indirect relationships with each other, and thus they could contribute to PTX resistance as a group. The varied expression status and regulation function of the TSGs on cell cycle in different cancers might play an important role in PTX resistance.

Conclusion

A further understanding of the roles of tumor suppressor genes in drug resistance is an important step to overcome chemotherapy tolerance. Tumor suppressor gene therapy targets the altered genes and signaling pathways and can be a new strategy to reverse chemotherapy resistance.

High levels of class III β-tubulin expression are associated with aggressive tumor features in breast cancer

Overexpression of class III β-tubulin (TUBB3), a factor that confers dynamic properties to microtubules, is a candidate biomarker for resistance to microtubule-targeting chemotherapeutics in breast and other types of solid cancer. Discrepant results from previous studies, with respect to the association of TUBB3 expression levels with breast cancer phenotype and patient prognosis, prompted the present study to investigate TUBB3 expression in a large cohort of breast cancer cases, with available clinical follow-up data. A preexisting breast cancer prognosis tissue microarray, containing a single 0.6 mm tissue core from each of 2,197 individual patients with breast cancer, was analyzed for TUBB3 expression by immunohistochemistry. The results of the present study revealed that TUBB3 expression was less frequent in lobular breast cancer cases (34%), compared with that of cancer cases of alternative histologies, including breast cancer of no special type (60%; P<0.0001). High TUBB3 positivity was associated with high tumor grade (P<0.0001), negativity for estrogen (P<0.0001) and progesterone receptors (P<0.004), as well as the presence of human epidermal growth factor 2 amplification (P<0.0001) and a triple-negative phenotype (P<0.0001). TUBB3 overexpression was additionally associated with reduced patient survival if all breast cancer cases of any histology were jointly analyzed (P=0.0088); however this link was not evident in the subset of breast cancer cases of no special type, or in a multivariate analysis including the established prognostic factors of tumor stage, grade and nodal stage. In conclusion, the present study demonstrated that TUBB3 overexpression was associated with adverse features of breast cancer, and that TUBB3 may possess a distinct role in lobular breast cancer cases, compared with alternative histological subtypes. The results of the present study do not support a clinically relevant role for TUBB3 as a prognostic marker in breast cancer.

Pharmacology of novel small-molecule tubulin inhibitors in glioblastoma cells with enhanced EGFR signalling

We recently reported that CMPD1, originally developed as an inhibitor of MK2 activation, primarily inhibits tubulin polymerisation and induces apoptosis in glioblastoma cells. In the present study we provide detailed pharmacological investigation of CMPD1 analogues with improved molecular properties. We determined their anti-cancer efficacy in glioblastoma cells with enhanced EGFR signalling, as deregulated EGFR often leads to chemoresistance. Eight analogues of CMPD1 with varying lipophilicity and basicity were synthesised and tested for efficacy in the cell viability assay using established glioblastoma cell lines and patient-derived primary glioblastoma cells. The mechanism of action for the most potent analogue 15 was determined using MK2 activation and tubulin polymerisation assays, together with the immunofluorescence analysis of the mitotic spindle formation. Apoptosis was analysed by Annexin V staining, immunoblotting analysis of bcl-2 proteins and PARP cleavage. The apoptotic activity of CMPD1 and analogue 15 was comparable across glioblastoma cell lines regardless of the EGFR status. Primary glioblastoma cells of the classical subtype that are characterized by enhanced EGFR activity were most sensitive to the treatment with CMPD1 and 15. In summary, we present mechanism of action for a novel small molecule tubulin inhibitor, compound 15 that inhibits tubulin polymerisation and mitotic spindle formation, induces degradation of anti-apoptotic bcl-2 proteins and leads to apoptosis of glioblastoma cells. We also demonstrate that the enhanced EGFR activity does not decrease the efficacy of tubulin inhibitors developed in this study.

Erlotinib versus carboplatin and paclitaxel in advanced lepidic adenocarcinoma: IFCT-0504

The IFCT-0504 phase II trial evaluated the efficacy of erlotinib versus carboplatin-paclitaxel (CP) as first-line treatment in 130 cases of advanced lepidic-predominant adenocarcinoma (ADC).The primary objective of the study was treatment efficacy, evaluated based on an end-point of disease control at 16 weeks.The primary objective was met, with a disease control in 35 (53%) out of 66 patients treated with CP and in 25 (39.1%) out of 64 patients treated with erlotinib. Median progression-free survival (PFS) for the total population was 3.6 months. The disease control rate did not differ between either the therapeutic arms or pathological subtypes, whereas there was a strong interaction between treatment arms and tumour pathological subtypes for PFS (p=0.009). Mucinous tumour patients treated with erlotinib exhibited an increased progression risk (hazard ratio 3.4, 95% CI 1.7-6.5; p≤0.001). The PFS for nonmucinous tumour patients was similar in both arms. Median overall survival was 20.1 months and did not differ between therapeutic arms. These findings were not further elucidated by molecular analyses and the toxicity profiles were as expected.Our study demonstrated the dominant role of CP alongside erlotinib in the management of advanced lepidic ADC. Based on these findings, erlotinib should not be administered in first-line therapy to patients with lepidic ADC in the absence of an epidermal growth factor receptor mutation.

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.

Nanoparticle-mediated drug delivery for treating melanoma

Melanoma originated from melanocytes is the most aggressive type of skin cancer with limited treatment options. New targeted therapeutic options with the discovery of BRAF and MEK inhibitors have shown significant survival benefits. Despite the recent progress, development of chemoresistance and systemic toxicity remains a challenge for treating metastatic melanoma. While the response from the first line of treatment against melanoma using dacarbazine remains only 5-10%, the prolonged use of targeted therapy against mutated oncogene BRAF develops chemoresistance. In this review, we will discuss the nanoparticle-based strategies for encapsulation and conjugation of drugs to the polymer for maximizing their tumor distribution through enhanced permeability and retention effect. We will also highlight photodynamic therapy and design of melanoma-targeted nanoparticles.

Tubulin Beta3 Serves as a Target of HDAC3 and Mediates Resistance to Microtubule-Targeting Drugs

We investigated the role of HDAC3 in anti-cancer drug-resistance. The expression of HDAC3 was decreased in cancer cell lines resistant to anti-cancer drugs such as celastrol and taxol. HDAC3 conferred sensitivity to these anti-cancer drugs. HDAC3 activity was necessary for conferring sensitivity to these anti-cancer drugs. The down-regulation of HDAC3 increased the expression of MDR1 and conferred resistance to anti-cancer drugs. The expression of tubulin β3 was increased in drug-resistant cancer cell lines. ChIP assays showed the binding of HDAC3 to the promoter sequences of tubulin β3 and HDAC6. HDAC6 showed an interaction with tubulin β3. HDAC3 had a negative regulatory role in the expression of tubulin β3 and HDAC6. The down-regulation of HDAC6 decreased the expression of MDR1 and tubulin β3, but did not affect HDAC3 expression. The down-regulation of HDAC6 conferred sensitivity to taxol. The down-regulation of tubulin β3 did not affect the expression of HDAC6 or MDR1. The down-regulation of tubulin β3 conferred sensitivity to anti-cancer drugs. Our results showed that tubulin β3 serves as a downstream target of HDAC3 and mediates resistance to microtubule-targeting drugs. Thus, the HDAC3-HDAC6-Tubulin β axis can be employed for the development of anti-cancer drugs.

Let-7 Sensitizes KRAS Mutant Tumor Cells to Chemotherapy

KRAS is the most commonly mutated oncogene in human cancers and is associated with poor prognosis and drug resistance. Let-7 is a family of tumor suppressor microRNAs that are frequently suppressed in solid tumors, where KRAS mutations are highly prevalent. In this study, we investigated the potential use of let-7 as a chemosensitizer. We found that let-7b repletion selectively sensitized KRAS mutant tumor cells to the cytotoxicity of paclitaxel and gemcitabine. Transfection of let-7b mimic downregulated the expression of mutant but not wild-type KRAS. Combination of let-7b mimic with paclitaxel or gemcitabine diminished MEK/ERK and PI3K/AKT signaling concurrently, triggered the onset of apoptosis, and reverted the epithelial-mesenchymal transition in KRAS mutant tumor cells. In addition, let-7b repletion downregulated the expression of β-tubulin III and ribonucleotide reductase subunit M2, two proteins known to mediate tumor resistance to paclitaxel and gemcitabine, respectively. Let-7 may represent a new class of chemosensitizer for the treatment of KRAS mutant tumors.

Class III β-tubulin in normal and cancer tissues

Microtubules are polymeric structures composed of tubulin subunits. Each subunit consists of a heterodimer of α- and β-tubulin. At least seven β-tubulin isotypes, or classes, have been identified in human cells, and constitutive isotype expression appears to be tissue specific. Class III β-tubulin (βIII-tubulin) expression is normally confined to testes and tissues derived from neural cristae. However, its expression can be induced in other tissues, both normal and neoplastic, subjected to a toxic microenvironment characterized by hypoxia and poor nutrient supply. In this review, we will summarize the mechanisms underlying βIII-tubulin constitutive and induced expression. We will also illustrate its capacity to serve as a biomarker of neural commitment in normal tissues and as a pure prognostic biomarker in cancer patients.

Use of TUBB3 for patient stratification and prognosis in lung cancer

SUMMARY 

Microtubules play a crucial role in the eukaryote replicative cell machinery and antimicrotubule drugs such as vinca alkaloids and taxanes are important drugs in the treatment of several solid tumors. TUBB3 has in retrospective studies shown to be of significance with regard to outcome in NSCLC patients treated with anti-microtubule drugs. However, it is still controversial whether or not TUBB3 has a prognostic or a predictive value. This review provides an overview of preclinical and clinical studies that have presented data on the role of TUBB3 in NSCLC.

Emerging microtubule targets in glioma therapy

Major advances in the genomics and epigenomics of diffuse gliomas and glioblastoma to date have not been translated into effective therapy, necessitating pursuit of alternative treatment approaches for these therapeutically challenging tumors. Current knowledge of microtubules in cancer and the development of new microtubule-based treatment strategies for high-grade gliomas are the topic in this review article. Discussed are cellular, molecular, and pharmacologic aspects of the microtubule cytoskeleton underlying mitosis and interactions with other cellular partners involved in cell cycle progression, directional cell migration, and tumor invasion. Special focus is placed on (1) the aberrant overexpression of βIII-tubulin, a survival factor associated with hypoxic tumor microenvironment and dynamic instability of microtubules; (2) the ectopic overexpression of γ-tubulin, which in addition to its conventional role as a microtubule-nucleating protein has recently emerged as a transcription factor interacting with oncogenes and kinases; (3) the microtubule-severing ATPase spastin and its emerging role in cell motility of glioblastoma cells; and (4) the modulating role of posttranslational modifications of tubulin in the context of interaction of microtubules with motor proteins. Specific antineoplastic strategies discussed include downregulation of targeted molecules aimed at achieving a sensitization effect on currently used mainstay therapies. The potential role of new classes of tubulin-binding agents and ATPase inhibitors is also examined. Understanding the cellular and molecular mechanisms underpinning the distinct behaviors of microtubules in glioma tumorigenesis and drug resistance is key to the discovery of novel molecular targets that will fundamentally change the prognostic outlook of patients with diffuse high-grade gliomas.

βIII-Tubulin Regulates Breast Cancer Metastases to the Brain

Brain metastases occur in about 10% to 30% of breast cancer patients, which culminates in a poor prognosis. It is, therefore, critical to understand the molecular mechanisms underlying brain metastatic processes to identify relevant targets. We hypothesized that breast cancer cells must express brain-associated markers that would enable their invasion and survival in the brain microenvironment. We assessed a panel of brain-predominant markers and found an elevation of several neuronal markers (βIII-tubulin, Nestin, and AchE) in brain metastatic breast cancer cells. Among these neuronal predominant markers, in silico analysis revealed overexpression of βIII-tubulin (TUBB3) in breast cancer brain metastases (BCBM) and its expression was significantly associated with distant metastases. TUBB3 knockdown studies were conducted in breast cancer models (MDA-Br, GLIM2, and MDA-MB-468), which revealed significant reduction in their invasive capabilities. MDA-Br cells with suppressed TUBB3 also demonstrated loss of key signaling molecules such as β3 integrin, pFAK, and pSrc in vitro. Furthermore, TUBB3 knockdown in a brain metastatic breast cancer cell line compromised its metastatic ability in vivo, and significantly improved survival in a brain metastasis model. These results implicate a critical role of TUBB3 in conferring brain metastatic potential to breast cancer cells.