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Aberrantly activated claudin 6 and 18.2 as potential therapy targets in non-small-cell lung cancer
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular and Morphological Pathology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular and Morphological Pathology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Immunology, Genetics and Pathology, Molecular and Morphological Pathology.
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2014 (English)In: International Journal of Cancer, ISSN 0020-7136, E-ISSN 1097-0215, Vol. 135, no 9, 2206-2214 p.Article in journal (Refereed) Published
Abstract [en]

Claudins (CLDNs) are central components of tight junctions that regulate epithelial-cell barrier function and polarity. Altered CLDN expression patterns have been demonstrated in numerous cancer types and lineage-specific CLDNs have been proposed as therapy targets. The objective of this study was to assess which fraction of patients with non-small-cell lung cancer (NSCLC) express CLDN6 and CLDN18 isoform 2 (CLDN18.2). Protein expression of CLDN6 and CLDN18.2 was examined by immunohistochemistry on a tissue microarray (n=355) and transcript levels were supportively determined based on gene expression microarray data from fresh-frozen NSCLC tissues (n=196). Both were analyzed with regard to frequency, distribution and association with clinical parameters. Immunohistochemical analysis of tissue sections revealed distinct membranous positivity of CLDN6 (6.5%) and CLDN18.2 (3.7%) proteins in virtually non-overlapping subgroups of adenocarcinomas and large-cell carcinomas. Pneumocytes and bronchial epithelial cells were consistently negative. Corresponding to the protein expression, in subsets of non-squamous lung carcinoma high mRNA levels of CLDN6 (7-16%) and total CLDN18 (5-12%) were observed. Protein expression correlated well with total mRNA expression of the corresponding gene (rho=0.4-0.8). CLDN18.2 positive tumors were enriched among slowly proliferating, thyroid transcription factor 1 (TTF-1)-negative adenocarcinomas, suggesting that isoform-specific CLDN expression may delineate a specific subtype. Noteworthy, high CLDN6 protein expression was associated with worse prognosis in lung adenocarcinoma in the univariate [hazard ratio (HR): 1.8; p=0.03] and multivariate COX regression model (HR: 1.9; p=0.02). These findings encourage further clinical exploration of targeting ectopically activated CLDN expression as a valuable treatment concept in NSCLC.

Place, publisher, year, edition, pages
2014. Vol. 135, no 9, 2206-2214 p.
Keyword [en]
non-small-cell lung cancer, targeted therapy, gene expression profiling, claudin, tissue microarray
National Category
Cancer and Oncology
URN: urn:nbn:se:uu:diva-235148DOI: 10.1002/ijc.28857ISI: 000341983700026PubMedID: 24710653OAI: oai:DiVA.org:uu-235148DiVA: diva2:761504

De 2 första författarna delar förstförfattarskapet. (The 2 first authors contributed equally to the study)

Available from: 2014-11-06 Created: 2014-10-29 Last updated: 2016-08-14
In thesis
1. An integrative strategy for targeted evaluation of biomarker expression in non-small cell lung cancer
Open this publication in new window or tab >>An integrative strategy for targeted evaluation of biomarker expression in non-small cell lung cancer
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Despite improvements in therapy, the prognosis for non-small cell lung cancer (NSCLC) patients remains poor, and cure is only possible in localized tumors after surgical resection. A new generation of targeted cancer drugs has led to the expectation that lung cancer therapy can be significantly improved, but these drugs are today only an option in a small subset of NSCLC patients, and their effect is temporary. Therefore, the aim of this thesis was to characterize NSCLC in order to find new treatment targets and to evaluate biomarkers that further optimize therapy selection.

In Paper I, the expression of the potential treatment targets claudin 6 and claudin 18.2 were evaluated based on immunohistochemical- and gene expression analysis. High ectopic protein and gene expression were demonstrated for both claudins in small subgroups of NSCLC. Clinical trials using humanized monoclonal antibodies against both proteins are ongoing in other cancer forms and may be extended to NSCLC.

In Paper II, the prognostic impact of the inflammatory mediator cyclooxygenase 2 (COX-2) was evaluated. No prognostic significance was found in a meta-analysis incorporating gene expression data of 1337 NSCLC patients. Likewise, COX-2 protein expression in tumor cells was not associated with survival in two independent NSCLC cohorts. However, in one of the analyzed cohorts, higher COX-2 expression in the tumor stroma was associated with longer survival and may therefore be a subject for further investigation.

In Paper III, tumor and stromal COX-2 protein expression was examined in patients treated with the COX-2 inhibitor celecoxib in order to evaluate if COX-2 expression is a predictive biomarker for benefit of celecoxib therapy. Celecoxib did not prolong overall survival neither in the whole cohort nor in patients stratified according to COX-2 expression in tumor or stromal cells. Noteworthy, a tendency towards longer survival was again demonstrated in patients with high COX-2 stromal expression.

In Paper IV, the diagnostic methods for identification of ALK rearrangements were assessed in a large representative Swedish NSCLC population. Fluorescence in situ hybridization (FISH), as the diagnostic standard, was compared to two immunohistochemical assays. ALK gene expression levels were incorporated to supplement the molecular data. The frequency of ALK rearrangements was lower than previously reported. The different methods to detect the ALK fusion demonstrated overlapping results. However, the overlap was poor, so the methods cannot be regarded as interchangeable and should thereby be interpreted with caution when used in clinical diagnostics.

In summary, this thesis applied an integrative translational approach to characterize potential new treatment targets and to evaluate the detection of existing predictive biomarkers in NSCLC.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. 58 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1229
non-small cell lung cancer, prognostic biomarkers, predictive biomarkers, immunohistochemistry, gene expression, COX-2, claudin, ALK
National Category
Other Medical Sciences Cancer and Oncology
Research subject
Medical Science
urn:nbn:se:uu:diva-285844 (URN)978-91-554-9584-8 (ISBN)
Public defence
2016-06-11, Fåhraeussalen, Rudbecklaboratoriet, Dag Hammarskjöldsväg 20, Uppsala, 09:15 (English)
Available from: 2016-05-19 Created: 2016-04-19 Last updated: 2016-06-01

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