Pancione et al. Journal of Translational Medicine 2013, 11:297 http://www.translational-medicine.com/content/11/1/297 RESEARCH Open Access The chromatin remodelling component SMARCB1/INI1 influences the metastatic behavior of colorectal cancer through a gene signature mapping to chromosome 22 Massimo Pancione1*†, Andrea Remo2†, Caterina Zanella2, Lina Sabatino1, Arturo Di Blasi3, Carmelo Laudanna1, Laura Astati2, Michele Rocco4, Delfina Bifano4, Paolo Piacentini2, Laura Pavan2, Alberto Purgato2, Filippo Greco2, Alberto Talamini2, Andrea Bonetti2, Michele Ceccarelli1, Roberto Vendraminelli2, Erminia Manfrin5 and Vittorio Colantuoni1* Background: INI1 (Integrase interactor 1), also known as SMARCB1, is the most studied subunit of chromatin remodelling complexes. Its role in colorectal tumorigenesis is not known. Methods: We examined SMARCB1/INI1 protein expression in 134 cases of colorectal cancer (CRC) and 60 matched normal mucosa by using tissue microarrays and western blot and categorized the results according to mismatch repair status (MMR), CpG island methylator phenotype, biomarkers of tumor differentiation CDX2, CK20, vimentin and p53. We validated results in two independent data sets and in cultured CRC cell lines. Results: Herein, we show that negative SMARCB1/INI1 expression (11% of CRCs) associates with loss of CDX2, poor differentiation, liver metastasis and shorter patients’ survival regardless of the MMR status or tumor stage. Unexpectedly, even CRCs displaying diffuse nuclear INI1 staining (33%) show an adverse prognosis and vimentin over-expression, in comparison with the low expressing group (56%). The negative association of SMARCB1/INI1-lack of expression with a metastatic behavior is enhanced by the TP53 status. By interrogating global gene expression from two independent cohorts of 226 and 146 patients, weconfirmtheprognosticresults and identify a gene signature characterized by SMARCB1/INI1 deregulation. Notably, the top genes of the signature (BCR, COMT, MIF) map on the long arm of chromosome 22 and are closely associated with SMARCB1/INI1. Conclusion: Our findings suggest that SMARCB1/INI1-dysregulation and genetic hot-spots on the long arm of chromosome 22 might play an important role in the CRC metastatic behavior and be clinically relevant as novel biomarkers. Keywords: Integrase interactor 1, Colorectal cancer, Chromosome 22 Background been identified at high frequency in a variety of tumors, The chromatin remodelling (CR) complexes dynamically highlighting the widespread role of epigenome alterations regulate transcription by using the energy from ATP hy- in tumor suppression or oncogenic activation [1]. Integrase drolysis to reposition nucleosomes and modulate accessibil- interactor 1 (INI1, also known as SMARCB1) is a core sub- ity of specific genes to the transcriptional machinery [1,2]. unit of the SWI/SNF ATP-dependent CR complex encoded Recently, inactivating mutations in the CR complexes have by the corresponding gene at chromosomal position 22q11.2 [3-5]. SMARCB1/INI1 is ubiquitously expressed in normal cells and can be readily identified by immunohistochemis- * Correspondence: [email protected]; [email protected] † try. SMARCB1/INI1 germ-line mutations were first de- Equal contributors 1Department of Sciences and Technologies, University of Sannio, Via Port’Arsa, scribed in the malignant rhabdoid tumors (MRT) of 11 82100 Benevento, Italy infancy and atypical theratoid/rhabdoid tumors of the Full list of author information is available at the end of the article © 2013 Pancione et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Pancione et al. Journal of Translational Medicine 2013, 11:297 Page 2 of 12 http://www.translational-medicine.com/content/11/1/297 central nervous system and define a hereditary condition Table 1 Correlation between SMARCB1/INI1 expression known as “Rhabdoid predisposition syndrome” [3-6]. pattern and patients’ clinico-pathological parameters Deletions at chromosome 22 or loss of SMARCB1/INI1 Parameters n INI1 P value expression have also been implicated in the pathogenesis Neg (%) Low (%) High (%) of additional tumor types: renal medullary carcinomas, Age ≤60 22 1 (4.5) 12 (54.5) 9 (41) 0.456 epithelioid sarcomas, myoepithelial carcinomas and extra- >60 112 14 (12.5) 63 (56.2) 35 (31.3) skeletal myxoid chondrosarcomas [7]. Although SMARCB1/ Sex F 49 9 (18.4) 21 (42.6) 19 (39) 0.056 INI1 is the most extensively studied subunit of the SWI/ SNF complex, very little is known about its role in the M 85 6 (7.1) 54 (63.5) 25 (29.4) pathogenesis of colorectal cancer (CRC) [8]. Recently, Location Proximal 51 5 (9.8) 34 (66.6) 12 (23.6) 0.136 we reported that SMARCB1/INI1 inactivation or, alter- Distal 83 10 (12) 41 (49.4) 32 (38.6) natively, a genomic rearrangement at the chromosome Histology ADC 108 10 (9.2) 62 (57.4) 36 (33.4) 0.667 region 22q12 are involved in Rhabdoid Colorectal Tumor A-Muc 17 3 (17.6) 9 (52.9) 5 (29.5) (RCT), a rare and highly aggressive neoplasm of the Other 9 2 (22.2) 4 (44.4) 3 (33.3) gastrointestinal tract [9,10]. SMARCB1/INI1-deficient mice develop rapidly aggressive undifferentiated sarco- Grade Well/mod 109 7 (6.4) 67 (61.5) 35 (32.1) 0.003* mas, implying a cancer-related function [11]. Notably, Poor 25 8 (32) 8 (32) 9 (36) in the same mouse model, the conditional inactivation N stage N0 88 7 (7.9) 51 (62.5) 30 (29.6) 0.387 of TP53 leads to a dramatic acceleration of tumor for- N1 24 3 (12.5) 14 (58.3) 7 (29.2) mation and a wider spectrum of cancers than those seen N2 22 5 (22.7) 10 (45.4) 7 (31.9) in TP53 deficient mice alone [12]. These results suggest LiverMet Negative 93 4 (4.3) 58 (62.4) 31 (33.3) 0.001* a cooperative effect of both genes to prevent oncogenic transformation and a dominant role of SMARCB1/INI1 Positive 41 11 (26.8) 17 (41.4) 13 (31.8) to hamper cancer aggressiveness. Despite the evidence Stage I 12 0 5 (41.6) 7 (58.4) 0.002* in mouse models, the link between SMARCB1/INI1 II 63 3 (4.8) 42 (66.6) 18 (28.6) alterations and the molecular changes underlying CRC III 20 1 (5) 12 (60) 7 (35) progression remains still poorly understood. In order IV 39 11 (28.2) 16 (41) 12 (30.8) to shed light on the biological role of SMARCB1/INI1, Total 134 15 (11) 75 (56) 44 (33) in this study we investigated its expression profile and Tumor classification was based on the TNM (Tumor-Node-Metastasis) system, evaluated the relationship between molecular alterations according to the criteria of the International Union Against Cancer (UICC). and clinico-histological markers of dedifferentiated and Abbreviations: Proximal caecum, ascending and transverse colon, Distal descending aggressive colorectal carcinomas. We hypothesize that and sigmoid colon, rectum, Adc adenocarcinoma, AD-Muc adenocarcinoma with a mucinous component below 50%, Other squamous or rhabdoid, Well/mod well and its assessment might be clinically relevant to predict moderately differentiated, Poor poorly differentiated adenocarcinoma, Liver Met CRC prognosis. Liver metastasis.*Chi-square statistic significant at the 0.01 level. Materials and methods Tumor samples and TMA construction were recorded. TMAs were constructed from archival Colorectal cancer specimens and matched normal mucosa tissue blocks of normal and colorectal cancer using a were collected at two institutions, Fatebenefratelli Hos- Beecher tissue microarray instrument (Beecher Instru- pital, Benevento, and Legnago Hospital, Verona, Italy. ments, Hacken-sack, NJ, USA). Tissue cylinders, with a This study was carried out according to the principles diameter of 0.6 mm, were punched from paraffin blocks of the Declaration of Helsinki with appropriate patient’s in demarcated areas on parallel haematoxylin&eosin- informed consent and approved by the Institutional stained sections. Three separate cores were sampled from Review Board of both hospitals. Altogether, a total of each block deposited into a recipient master paraffin 134 patients, 85 men and 49 women with mean age block. Each core was placed 1 mm apart on the x-axis of 70.5 ± 11.8 were analyzed. The tumors were classified and 1.5 mm apart on the y-axis of the master block. In and graded according to the criteria of the TNM and total, 12 microarrays paraffin block were prepared, 4 μ tumor stages I-IV classification systems, (Table 1). None thick sections were cut from each TMA block and of the patients had a familial history of intestinal dys- stained with haematoxylin&eosin. Microarray sections function or CRC, had received chemotherapy or radiation were then reviewed to ensure that the sections from prior to resection nor had taken non-steroidal anti- each case were morphologically similar to those of the inflammatory drugs on a regular basis. For each patient, corresponding whole tissue section and represented can- the date of colon cancer diagnosis, date of last follow- cerous or normal epithelial cells. Further 4 μ thick sec- up, and vital status at last follow-up (i.e., living or deceased) tions were then cut from each of the master blocks for Pancione et al. Journal of Translational Medicine 2013, 11:297 Page 3 of 12 http://www.translational-medicine.com/content/11/1/297 immunohistochemical (IHC) analyses, the cores contain- MLH1 or MSH2 or MSH6 or PMS2. Inflammatory and ing too little tumor sample were not included in the study. stromal cells adjacent to neoplastic cells served as posi- Due to technical problems and/or tissue exhaustion, the tive internal controls.