6p22.3 amplification as a biomarker and potential therapeutic target of advanced stage bladder cancer

He Shen,Carl D Morrison,Anna Woloszynska-Read,Kevin Eng,Jianmin Wang,Annette Hill,Costa Frangou,Donald L Trump,Candace S Johnson,Karen Head,Amyn M Rojiani,Jianmin Zhang,Roni J Bollag,Sravan K Kavuri,Yingwei Li,Song Liu,Willie Underwood,Nuo Yang,Li Yan

doi:10.18632/oncotarget.1485

He Shen, Carl D Morrison + Show 17 more

Open Access

https://doi.org/10.18632/oncotarget.1485

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Journal: Oncotarget	Publication Date: Oct 29, 2013
Citations: 54	License type: cc-by

Affiliation: Roswell Park Cancer Institute, Augusta University

Abstract

Genetic and epigenetic alterations have been identified as to contribute directly or indirectly to the generation of transitional cell carcinoma of the urinary bladder (TCC-UB). In a comparative fashion much less is known about copy number alterations in TCC-UB, but it appears that amplification of chromosome 6p22 is one of the most frequent changes. Using fluorescence in situ hybridization (FISH) analyses, we evaluated chromosomal 6p22 amplification in a large cohort of bladder cancer patients with complete surgical staging and outcome data. We have also used shRNA knockdown candidate oncogenes in the cell based study. We found that amplification of chromosome 6p22.3 is significantly associated with the muscle-invasive transitional cell carcinoma of the urinary bladder (TCC-UB) (22%) in contrast to superficial TCC-UB (9%) (p=7.2-04). The rate of 6p22.3 amplification in pN>1 patients (32%) is more than twice that in pN0 (16%) patients (p=0.05). Interestingly, we found that 6p22.3 amplification is as twice as high (p=0.0201) in African American (AA) than European American (EA) TCC-UB patients. Moreover, we showed that the expression of some candidate genes (E2F3, CDKAL1 and Sox4) in the 6p22.3 region is highly correlated with the chromosomal amplification. In particular, knockdown of E2F3 inhibits cell proliferation in a 6p22.3-dependent manner, whereas knockdown of CDKAL1 and Sox4 has no effect on cell proliferation. Using gene expression profiling, we further identified some common as well as distinctive subset targets of the E2F3 family members. In summary, our data indicate that E2F3 is a key regulator of cell proliferation in a subset of bladder cancer and the 6p22.3 amplicon is a biomarker of aggressive phenotype in this tumor type.

Highlights

Many genetic and epigenetic alterations have been identified as to contribute directly or indirectly to the generation of transitional cell carcinoma of the urinary bladder (TCC-UB)
In our cohort of TCC-UB, we found that chromosome 6p22.3 is frequently amplified in the muscle-invasive subset and has significant correlation to tumor stage
Proliferation advantage of the 5637 bladder cancer cell line is highly dependent on the 6p22.3 amplicon, in particular, the E2F3 gene within the locus, and www.impactjournals.com/oncotarget knockdown of E2F3a or E2F3b significantly reduced cell proliferation

Summary

INTRODUCTION

Many genetic and epigenetic alterations have been identified as to contribute directly or indirectly to the generation of transitional cell carcinoma of the urinary bladder (TCC-UB). Oncotarget 2013; 4: grade superficial TCC-UB are most frequently caused by activating mutations of proto-oncogenes, of which fibroblast growth factor receptor 3 (FGFR3) and HRAS are most prevalent, with mutations in up to 75% and 30% of the papillary tumors, respectively [1, 2]. Since both these oncogenes activate the RAS/MEK/ERK signaling pathway, they appear to be mutually exclusive [3]. The majority of muscle-invasive TCC-UB arises through inactivation of the tumor suppressor pathways of TP53, RB1 or PTEN [1, 4]. We further characterized E2F3 as a major cell proliferation effector of 6p22 amplification and identified distinct target genes regulated by the E2F3 family members

38 African and 1 Asian Total

DISCUSSION

METHODS