Alterations of ROBO1/DUTT1 and ROBO2 loci in early dysplastic lesions of head and neck: clinical and prognostic implications

Abstract

Deletion of chromosomal 3p12.3 was suggested to be associated with dysplastic lesions of head and neck. This region harbors two candidate tumor suppressors ROBO1/DUTT1, ROBO2 and two non-coding RNAs (ncRNAs) located at intron 2 of ROBO1/DUTT1. Aim of this study is to understand the role of these genes in development of head and neck squamous cell carcinoma. A collection of 72 dysplastic lesions and 116 HNSCC samples and two oral cancer cell lines were analyzed for ROBO1/DUTT1 and ROBO2 deletion and promoter methylation. ROBO1/DUTT1, ROBO2 and two ncRNAs mRNA expression were analyzed by Q-PCR. Immunohistochemical analysis of ROBO1/DUTT1 and ROBO2 was performed. Alterations of these genes were correlated with different clinicopathological parameters. High frequency of molecular alterations (deletion/methylation) was seen in ROBO1/DUTT1 than ROBO2. In mild dysplastic lesions both of these genes showed high molecular alterations and remained more or less constant in subsequent stages. Q-PCR analysis showed reduced expression of these genes and the two ncRNAs. In vitro demethylation experiment by 5-aza-dC showed upregulation of ROBO1/DUTT1 and ROBO2 while the expression of the ncRNAs remained unchanged. Immunohistochemical analysis of ROBO1/DUTT1 and ROBO2 showed concordance with their mRNA expression and molecular alterations. Poor patients' outcome was predicted in the cases with alteration of ROBO1/DUTT1 along with tobacco addiction and nodal involvement. Our data suggests (a) ROBO1/DUTT1 and the ncRNAs are transcribed from different promoters, and (b) inactivation of ROBO1/DUTT1 could be used as molecular signature for early detection and prognosis of the head and neck cancer.

Frequent inactivation of SLIT2 and ROBO1 signaling in head and neck lesions: clinical and prognostic implications

“…Similar findings have also been reported in carcinomas of the cervix, lung, and breast 13,15,28,29 In our previous study of ROBO1 alteration (deletion/ methylation) in HNSCC development, frequent alteration of ROBO1 was seen in dysplastic and invasive lesions. 7 In this study, to understand the association of SLIT2-ROBO1 in the development of HNSCC some common samples of dysplastic lesions (n ¼ 25) and invasive lesions (n ¼ 72) of the previous study were used along with some freshly collected samples (dysplastic lesions: 5; invasive lesions: 56). The ROBO1 alteration had concordance with the previous study.…”

“…7 Mice harboring deletions of exon 2 of ROBO1 spontaneously developed bronchial epithelial hyperplasia, indicating it as a candidate tumor suppressor gene (TSG). 8 Our previous study also found a high frequency of molecular alterations (deletion/ methylation) and concordant reduced expression of ROBO1 in head and neck lesions, indicating importance of this gene in the development of HNSCC.…”

“…8 Our previous study also found a high frequency of molecular alterations (deletion/ methylation) and concordant reduced expression of ROBO1 in head and neck lesions, indicating importance of this gene in the development of HNSCC. 7 ROBO1 serves as a receptor of the SLIT2-ROBO1 signaling pathway. Drosophila homolog SLIT2 homology 2 (SLIT2) protein contains a unique N-terminal tandem of 4 leucine-rich repeat (LRR) domains.…”

Selective gene expression by rat gastric corpus epithelium

“…Many of these protective genes encode membrane bound or secreted proteins, and their expression is downregulated in GI carcinomas (20,54,60,61). Muc1, 5ac, and 6 are highly enriched and are main constituents of the mucus barrier in the stomach, which protects the underlying epithelium from proteases, mechanical trauma, and pathogenic microorganisms (35).…”

Cytogenetic characterization of HB2 epithelial cells from the human breast

“…As an example, molecular alterations of ROBO1 and -2 genes, mapping into 3p12 band, are known to be linked to carcinogenesis (Ghosh et al 2009), whereas zinc finger protein 133 and protein tyrosine phosphatase , receptor type, T genes, located in 20p11.23 and 20q12-q13 regions, respectively, are recognized regulators of cell growth, differentiation, mitotic cycle, and oncogenic transformation (Lee et al 2007;Scott and Wang 2011).…”