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M. Lambe
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ORAL 41 - Immune Biology, Microenvironment and Novel Targets (ID 159)
- Event: WCLC 2015
- Type: Oral Session
- Track: Biology, Pathology, and Molecular Testing
- Presentations: 1
- Moderators:S.K. Padda, R. Nemenoff
- Coordinates: 9/09/2015, 18:30 - 20:00, Four Seasons Ballroom F1+F2
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ORAL41.07 - The Identification of Therapeutic Targets in Lung Cancer Based on Transcriptomic and Proteomic Characterization of Cancer-Testis Antigens (ID 1555)
18:30 - 20:00 | Author(s): M. Lambe
- Abstract
- Presentation
Background:
Most immunotherapeutic modalities are based on the concept that the immune system can attack targets that are specifically expressed in cancer cells. Cancer testis antigens (CTAs) are a group of genes with a broad expression in cancers including non-small cell lung cancer (NSCLC). In normal tissues the expression of CTAs is restricted to immune privileged organs such as testis and placenta. This limited expression in somatic tissues renders CTAs as a valuable group of genes for the exploration of potential immunotherapeutic targets. The aim of this study was to comprehensively explore the CTA repertoire in NSCLC and to try identifying new CTAs.
Methods:
RNA sequencing (RNAseq) was performed on 202 NSCLC samples from a consecutive clinical cohort of surgically resected patients. For the analysis of the comprehensive CTA expression profile in NSCLC we used Cancer Testis (CT) Database containing all genes reported as CTAs in the literature. The NSCLC transcriptome was compared to the normal transcriptome comprising of 22 paired normal lung tissues as well as to 122 samples from 32 different normal human tissues. Corresponding protein expression was evaluated by using immunohistochemistry (IHC) on tissue microarrays (TMAs) containing tumor tissue from the same patients as used in the RNA sequencing.
Results:
Of the 276 established CTAs, 155 genes (56%) were restricted to testis and placenta among normal tissues and were identified as CTAs. One third (35%) was expressed in at least one of the 202 individual NSCLC cases and 28 of these genes were previously not reported to be expressed as CTAs in NSCLC. Applying stringent analysis criteria on our RNA sequencing data set we identified 61 genes that were expressed in NSCLC and testis or placenta, but not in other normal tissues. Thus, these genes present potential new CTAs. The specific cancer/testis expression of selected genes (ZNF560, TGIF2LX, TFPI2, HMGB3, TKTL1 and STK31) from this group was confirmed on protein level using IHC. Additional analysis revealed that most CTAs were concurrently expressed in adenocarcinoma and squamous cell carcinoma. The expression of a subset of genes was histology dependent, with predominant expression in adenocarcinoma (e.g. XAGE family members) and in squamous cell carcinoma (e.g. MAGE family members).
Conclusion:
Our study provides deep sequencing mRNA expression profiles of the whole CTA repertoire in NSCLC. Several CTAs previously identified in other cancers but not analyzed in NSCLC have been identified on both mRNA and protein level. Additionally, we have identified 61 novel genes as CTAs in NSCLC that previously have not been reported as CTAs and several of these were also confirmed on protein level. This data offers the opportunity to design individual therapy options to target single CTAs or CTA clusters.
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