LIMD1 is more frequently altered than RB1 in head and neck squamous cell carcinoma: clinical and prognostic implications

Abstract

IntroductionTo understand the role of two interacting proteins LIMD1 and pRB in development of head and neck squamous cell carcinoma (HNSCC), alterations of these genes were analyzed in 25 dysplastic head and neck lesions, 58 primary HNSCC samples and two HNSCC cell lines.MethodsDeletions of LIMD1 and RB1 were analyzed along with mutation and promoter methylation analysis of LIMD1. The genotyping of LIMD1 linked microsatellite marker, hmlimD1, was done to find out any risk allele. The mRNA expression of LIMD1 and RB1 were analyzed by Q-PCR. Immunohistochemical analysis of RB1 was performed. Alterations of these genes were correlated with different clinicopathological parameters.ResultsHigh frequency [94% (78/83)] of LIMD1 alterations was observed in the samples studied. Compare to frequent deletion and methylation, mutation of LIMD1 was increased during tumor progression (P = 0.007). Six novel mutations in exon1 and one novel intron4/exon5 splice-junction mutation were detected in LIMD1 along with a susceptible hmlimD1 (CA)20 allele. Some of these mutations [42% (14/33)] produced non-functional proteins. RB1 deletion was infrequent (27%). Highly reduced mRNA expression of LIMD1 (25.1 ± 19.04) was seen than RB1 (3.8 ± 8.09), concordant to their molecular alterations. The pRB expression supported this data. Tumors with LIMD1 alterations in tobacco addicted patients without HPV infection showed poor prognosis. Co-alterations of these genes led the worse patients' outcome.ConclusionsOur study suggests LIMD1 inactivation as primary event than inactivation of RB1 in HNSCC development.

A HIF – LIMD 1 negative feedback mechanism mitigates the pro‐tumorigenic effects of hypoxia

“…The lung tumour suppressor protein LIMD1 is a member of the Zyxin family of adaptor proteins, initially characterised as signal transducers (Kadrmas & Beckerle, ) shuttling between the cytoplasm and nucleus. LIMD1 loss has been identified in lung, breast, head and neck squamous cell carcinomas, and adult acute leukaemia (Sharp et al , , ; Spendlove et al , ; Ghosh et al , ; Liao et al , ), and its decreased expression in diffuse large B‐cell lymphoma has clinical significance to patient prognosis and disease classification/stratification (Xu et al , ). Limd1 ‐knockout mice have increased lung tumour numbers and volume and decreased survival rate compared to Limd1‐ expressing control mice when either challenged with a chemical carcinogen or cross‐bred with Kras G12D mice (Sharp et al , ) validating its critical role in normal cellular homeostasis.…”

LIMD1 antagonizes E2F1 activity and cell cycle progression by enhancing Rb function in cancer cells

“…LIMD1 overexpression blocks tumour growth in vitro and in vivo, assigning it the role of a bona fide tumour suppressor gene product (Sharp et al, 2004. In line with these reports, LIMD1 expression is compromised, due to genetic and epigenetic modifications in human lung cancer Spendlove et al, 2008;Ghosh et al, 2008Ghosh et al, , 2010. Although binding of LIMD1 with Rb has been characterised, its effect on Rb status and function and cell cycle regulation are poorly understood.…”

LIMD1 (LIM domains containing 1)

“…Cytogenetics Loss of heterozygosity in chromosome 3p21.3 was found to be highly frequent in Indian HNSCC patients (Ghosh et al, 2008). The same group later reported alteration of LIMD1 in the majority of HNSCC samples studied, and increasing mutation, but not deletion or methylation, with tumour progression (Ghosh et al, 2010). Six mutations in exon 1, an intron 4/exon 5 splice-junction mutation in LIMD1 and a (CA) 20 polymorphism of the hmlimd1 microsatellite marker were reported, some of which lead to nonfunctional LIMD1 or reduced expression of LIMD1 (Ghosh et al, 2010).…”

“…Six mutations in exon 1, an intron 4/exon 5 splice-junction mutation in LIMD1 and a (CA) 20 polymorphism of the hmlimd1 microsatellite marker were reported, some of which lead to nonfunctional LIMD1 or reduced expression of LIMD1 (Ghosh et al, 2010). Oncogenesis Ghosh et al (2010) have proposed that repression of LIMD1, rather than pRB, is crucial for HNSCC development, due to the higher frequency of LIMD1 alterations compared with pRB alterations in the HNSCC samples analysed and better survival of patients with LIMD1 …”

“…Risk factors include smoking, alcohol, betel nut leaf liquid, HPV-16/18 infection and inadequate oral hygiene. Prognosis Ghosh et al (2010) have suggested LIMD1 as a "predictive clinical marker" for HNSCC from their multivariate analysis showing significant correlation of LIMD1 alteration (deletion/methylation/mutation) to poor prognosis in HPV-negative patients addicted to tobacco. Cytogenetics Loss of heterozygosity in chromosome 3p21.3 was found to be highly frequent in Indian HNSCC patients (Ghosh et al, 2008).…”