Expression profiling stratifies mesothelioma tumors and signifies deregulation of spindle checkpoint pathway and microtubule network with therapeutic implications.

Abstract

BACKGROUND:

Malignant pleural mesothelioma (MPM) is a lethal neoplasm exhibiting resistance to most treatment regimens and requires effective therapeutic options. Though an effective strategy in many cancer, targeted therapy is relatively unexplored in MPM because the therapeutically important oncogenic pathways and networks in MPM are largely unknown.

MATERIALS AND METHODS:

We carried out gene expression microarray profiling of 53 surgically resected MPMs tumors along with paired normal tissue. We also carried out whole transcriptomic sequence (RNA-seq) analysis on eight tumor specimens. Taqman-based quantitative Reverse-transcription polymerase chain reaction (qRT-PCR), western analysis and immunohistochemistry (IHC) analysis of mitotic arrest deficient-like 1 (MAD2L1) was carried out on tissue specimens. Cell viability assays of MPM cell lines were carried out to assess sensitivity to specific small molecule inhibitors.

RESULTS:

Bioinformatics analysis of the microarray data followed by pathway analysis revealed that the mitotic spindle assembly checkpoint (MSAC) pathway was most significantly altered in MPM tumors with upregulation of 18 component genes, including MAD2L1 gene. We validated the microarray data for MAD2L1 expression using quantitative qRT-PCR and western blot analysis on tissue lysates. Additionally, we analyzed expression of the MAD2L1 protein by IHC using an independent tissue microarray set of 80 MPM tissue samples. Robust clustering of gene expression data revealed three novel subgroups of tumors, with unique expression profiles, and showed differential expression of MSAC pathway genes. Network analysis of the microarray data showed the cytoskeleton/spindle microtubules network was the second-most significantly affected network. We also demonstrate that a nontaxane small molecule inhibitor, epothilone B, targeting the microtubules have great efficacy in decreasing viability of 14 MPM cell lines.

CONCLUSIONS:

Overall, our findings show that MPM tumors have significant deregulation of the MSAC pathway and the microtubule network, it can be classified into three novel molecular subgroups of potential therapeutic importance and epothilone B is a promising therapeutic agent for MPM.

• Authors: M B Suraokar, M I Nunez, L Diao, C W Chow, D Kim, C Behrens, H Lin, S Lee, G Raso, C Moran, D Rice, R Mehran, J J Lee, H I Pass, J Wang, A A Momin, B P James, A Corvalan, K Coombes, A Tsao, I I Wistuba
• Journal: Annals of oncology : official journal of the European Society for Medical Oncology (Ann Oncol) Vol. 25 Issue 6 Pg. 1184-92 (Jun 2014) ISSN: 1569-8041 [Electronic] England
• PMID: 24669013 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © The Author 2014. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: [email protected].

Chemical References

• Adaptor Proteins, Signal Transducing
• Antineoplastic Agents
• Cell Cycle Proteins
• Epothilones
• MAD2L1BP protein, human
• Nuclear Proteins
• Tubulin Modulators
• epothilone B

Topics

• Adaptor Proteins, Signal Transducing (genetics, metabolism)
• Antineoplastic Agents (pharmacology)
• Blotting, Western
• Cell Cycle Proteins (genetics, metabolism)
• Cell Line, Tumor
• Cluster Analysis
• DNA Mutational Analysis
• Epothilones (pharmacology)
• Gene Expression Profiling
• Humans
• Immunohistochemistry
• Lung Neoplasms (genetics)
• M Phase Cell Cycle Checkpoints (genetics)
• Mesothelioma (genetics)
• Mesothelioma, Malignant
• Microtubules (pathology)
• Nuclear Proteins (genetics, metabolism)
• Oligonucleotide Array Sequence Analysis
• Pleural Neoplasms (genetics, pathology)
• Real-Time Polymerase Chain Reaction
• Reverse Transcriptase Polymerase Chain Reaction
• Tissue Array Analysis
• Transcriptome
• Tubulin Modulators (pharmacology)