Submaxillary gland androgen-regulated protein 3A expression is an unfavorable risk factor for the survival of oropharyngeal squamous cell carcinoma patients after surgery.

Recently, increased expression of the submaxillary gland androgen-regulated protein 3A (SMR3A) was found in recurrent tumors of an orthotopic floor-of-mouth mouse tumor model after surgery. However, SMR3A expression in the pathogenesis of human malignancy and its correlation with the clinical outcome have not been addressed so far. We analyzed tissue microarrays with specimens from oropharyngeal squamous cell carcinoma (OPSCC) patients (n = 157) by immunohistochemistry and compared SMR3A expression with clinical and pathological features by statistical analysis. Strong SMR3A expression was found in almost 36 % of all primary OPSCCs. Although, SMR3A protein levels were not associated with any clinical or histopathological feature tested, univariate Kaplan-Meier analysis revealed a significant correlation between high SMR3A protein expression and poor progression-free (p = 0.02) and overall survival (p = 0.03). Furthermore, high SMR3A expression was an independent marker for poor clinical outcome [HR (SMR3A(high) vs. SMR3(low)) = 2.32; 95 % CI = 1.03-5.23] concerning overall survival in a multivariate analysis of OPSCC patients with surgery as primary therapy (n = 100). Our data demonstrate for the first time increased SMR3A protein expression in the pathogenesis of OPSCC, which serves as an unfavorable risk factor for patient survival.

Opposing function of MYBBP1A in proliferation and migration of head and neck squamous cell carcinoma cells.

BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is one of the most prevalent and lethal cancers worldwide and mortality mostly results from loco-regional recurrence and metastasis. Despite its significance, our knowledge on molecular, cellular and environmental mechanisms that drive disease pathogenesis remains largely elusive, and there are limited therapeutic options, with only negligible clinical benefit. METHODS: We applied global gene expression profiling with samples derived from a recently established mouse model for oral cancer recurrence and identified a list of genes with differential expression between primary and recurrent tumors. RESULTS: One differentially expressed gene codes for Myb-binding protein 1a (MYBBP1A), which is known as a transcriptional co-regulator that physically interacts with nuclear transcription factors, such as NFκB and p53. We confirmed significantly reduced MYBBP1A protein levels on tissue sections of recurrent mouse tumors compared to primary tumors by immunohistochemistry, and found aberrant MYBBP1A protein levels also in tumor samples of HNSCC patients. Interestingly, silencing of MYBBP1A expression in murine SCC7 and in human HNSCC cell lines elicited increased migration but decreased cell growth. CONCLUSION: We provide experimental evidence that MYBBP1A is an important molecular switch in the regulation of tumor cell proliferation versus migration in HNSCC and it will be a major challenge for the future to proof the concept whether regulation MYBBP1A expression and/or function could serve as a novel option for anti-cancer therapy.

Predictive value of epigenetic alterations in head and neck squamous cell carcinoma.

Head and neck cancer collectively describes malignant tumors originating from the mucosal surface of the upper aerodigestive tract. These tumors pose a great threat to public health because of their high incidence and mortality. Traditional risk factors are tobacco and alcohol abuse. More recently, infection by high-risk types of human papilloma virus (HPV) has been identified as an additional risk factor, especially for oropharyngeal squamous cell carcinoma (OPSCC). Moreover, HPV-positive OPSCC is considered a distinct tumor entity with an improved clinical outcome compared to HPV-negative OPSCC. Epigenetic alterations act as key events in the pathogenesis of cancer and are of special interest for basic and translational oncology because of their reversible nature. This review provides a comprehensive summary of alterations of the epigenome in head and neck squamous cell carcinoma (HNSCC) with a focus on the methylome (hypomethylation and hypermethylation) and its predictive value in the evaluation of pathologic states and clinical outcome, or monitoring response rates to certain therapies.

The tightly controlled deubiquitination activity of the human SAGA complex differentially modifies distinct gene regulatory elements.

The multisubunit SAGA coactivator complex facilitates access of general transcription factors to DNA through histone acetylation mediated by GCN5. USP22 (ubiquitin-specific protease 22) was recently described as a subunit of the human SAGA complex that removes ubiquitin from monoubiquitinated histone H2B and H2A in vitro. Here we demonstrate an allosteric regulation of USP22 through multiple interactions with different domains of other subunits of the SAGA deubiquitination module (ATXN7, ATXN7L3, and ENY2). Downregulation of ATXN7L3 by short hairpin RNA (shRNA) specifically inactivated the SAGA deubiquitination activity, leading to a strong increase of global H2B ubiquitination and a moderate increase of H2A ubiquitination. Thus, SAGA is the major H2Bub deubiquitinase in human cells, and this activity cannot be fully compensated by other deubiquitinases. Here we show that the deubiquitination activity of SAGA is required for full activation of SAGA-dependent inducible genes. Interestingly, the reduction of the SAGA deubiquitination activity and the parallel increase in H2B ubiquitation at inducible target genes before activation do not induce aberrant gene expression. Our data together indicate that different dynamic equilibriums of H2B ubiquitination/deubiquitination are established at different gene regulatory elements and that H2B ubiquitination changes are necessary but not sufficient to trigger parallel activation of gene expression.