Sabrina D. Silva

Clinicopathological significance of ubiquitin-specific protease 2a (USP2a), fatty acid synthase (FASN), and ErbB2 expression in oral squamous cell carcinomas

Overexpression of fatty acid synthase (FASN) and ErbB2 has been described in oral squamous cell carcinomas (OSCC). FASN is the key lipogenic enzyme responsible for the endogenous synthesis of fatty acids and its expression can be regulated by ErbB2. The deubiquitinating enzyme (DUB) ubiquitin-specific protease 2a (USP2a) plays a critical role in prostate cancer cell survival by stabilizing the FASN protein. This study investigates whether the gene expression and the immunohistochemical status of FASN, ErbB2, and USP2a correlate with the clinicopathological characteristics of OSCC cases. A strong positive correlation among ErbB2, FASN, and USP2a expression (p=0.001) was observed by qRT-PCR in laser capture microdissected OSCC samples. Perineural infiltration was associated with ErbB2 mRNA expression (p=0.046). The presence of metastatic cervical lymph nodes was associated with FASN (p=0.002), ErbB2 (p=0.001), and USP2a (p=0.006) mRNA levels. ErbB2 staining at the cell membranes was stronger in well-differentiated lesions while a cytoplasmic positivity was found in poorly differentiated tumors. Most of the OSCC (97.06%) that showed a high positivity for FASN were also labeled for ErbB2 at the cell membranes (p=0.001). FASN and ErbB2 positivity was associated with tumor thickness and lymphatic embolization (p=0.006 and p=0.035, p=0.006 and p=0.024 respectively). The membrane expression of ErbB2 as well as FASN and Ki-67 staining were significantly associated with a high risk of recurrence by predicting both disease free survival (log-rank test, p=0.0056, p=0.0011, and p=0.0004, respectively) and overall survival (log-rank test, p=0.0005, p=0.0062, and p=0.0001, respectively). Taken together, the results presented here suggest a molecular connection among FASN, ErbB2, and USP2a in OSCC since their mRNA and protein levels were associated with tumor progression and poor prognosis.

Fatty acid synthase expression in squamous cell carcinoma of the tongue: clinicopathological findings

BACKGROUNDnOverexpression of fatty acid synthase (FAS), the cytosolic enzyme responsible for the conversion of dietary carbohydrates to fatty acids, has been reported in several human malignancies and pointed as a potential prognostic marker for some tumors. This study investigated whether FAS immunohistochemical expression is correlated with the clinicopathological characteristics of oral squamous cell carcinoma (OSCC).nnnMATERIALS AND METHODSnThe clinical features of 102 patients with OSCC of the tongue treated in a single institution were obtained from the medical records and all histopathological diagnoses were reviewed. The expression of FAS was determined by the standard immunoperoxidase technique in formalin-fixed and paraffin-embedded specimens and correlated with the clinicopathological characteristics of the tumors.nnnRESULTSnEighty-one cases (79.41%) were positive for FAS. Microscopic characteristics such as histological grade (P < 0.05), lymphatic permeation (P < 0.001), perineural infiltration (P < 0.05), and nodal metastasis (P < 0.02) were associated with FAS status. A significantly lower survival probability for patients with advanced clinical stage (log-rank test, P < 0.001), lymph nodes metastasis (log-rank test, P < 0.001), presence of vascular permeation (log-rank test, P = 0.05), and perineural invasion (log-rank test, P = 0.01) was observed in the studied samples.nnnCONCLUSIONnThe expression of FAS in OSCC of the tongue is associated with the microscopic characteristics that determine disease progression and prognosis.

ErbB receptors and fatty acid synthase expression in aggressive head and neck squamous cell carcinomas

SUMMARYnOverexpression of ErbB receptors is frequent in head and neck squamous cell carcinomas (HNSCC) and seems to be correlated with tumor progression and metastasis. Fatty acid synthase (FASN), the key lipogenic enzyme responsible for the endogenous synthesis of fatty acids, is regulated by ErbB2 and overexpressed in several human malignancies.nnnMETHODSnThis study was performed to examine the immunohistochemical expression patterns of ErbB1, ErbB2, ErbB3, ErbB4, and FASN in a tissue microarray, containing 33 representative areas from aggressive primary HNSCC (whose patients had distant metastasis), and 21 matched lung metastasis.nnnRESULTSnStrong correlation among the expression of ErbB family receptors was found (ErbB1-ErbB2 P = 0.008, ErbB1-ErbB4 P = 0.018, EbB2-ErbB3 P = 0.001, ErbB2-ErbB4 P = 0.006, ErbB3-ErbB4 P=0.012) in the HNSCC. FASN expression was significantly associated with ErbB2 (P = 0.024). Lymphatic permeation was correlated with ErbB3 (P = 0.033) and histological grade with ErbB4 staining (P = 0.050). ErbB1 and ErbB2 were found mainly in patients with smoking habit (P = 0.011 and P = 0.027), and ErbB2 was associated with alcohol consumption and clinical stage (P = 0.014 and P = 0.031). Finally, FASN was overexpressed in lung metastasis, in comparison with matched HNSCC samples (P = 0.006).nnnCONCLUSIONSnu2002 The results showed that high FASN immunohistochemical expression is a feature of HNSCC lung metastasis, and ErbB1-ErbB2, ErbB1-ErbB4, ErbB2-ErbB3, ErbB2-ErbB4, and ErbB3-ErbB4 expression levels are correlated in the respective primary tumors, being ErbB2 the preferred coexpression partner of all the other ErbB receptors.

Differential expression of fatty acid synthase (FAS) and ErbB2 in nonmalignant and malignant oral keratinocytes

The aim of this study was to investigate fatty acid synthase (FAS) and ErbB2 expression in nonmalignant oral epithelium and oral or head and neck squamous cell carcinomas (OSCC/HNSCC). Morphologically normal, hyperkeratotic, and dysplastic oral epithelium as well as well-differentiated and poorly differentiated OSCC were immunohistochemically evaluated for FAS, ErbB2, and Ki-67. These proteins were also analyzed in a tissue microarray with 55 HNSCC. SCC-9 cells were used to study FAS and ErbB2 during differentiation. FAS expression was higher in hyperkeratosis, dysplasias, and OSCC than in normal epithelium. Well-differentiated OSCC/HNSCC were more positive for FAS than the poorly differentiated tumors. ErbB2 was observed at the surface of nonmalignant and well-differentiated OSCC/HNSCC keratinocytes and in the cytoplasm of poorly differentiated cells. Ki-67 index was progressively higher from normal oral epithelium to OSCC, inversely correlated with cell surface ErbB2, and positively correlated with intracytoplasmic ErbB2. Finally, SCC-9 cell cultures were enriched in membrane ErbB2-positive cells after differentiation by anchorage deprivation. In conclusion, FAS is overexpressed in OSCC/HNSCC and hyperkeratotic oral epithelium and ErbB2 is found at the cell surface of differentiating keratinocytes and in the cytoplasm of poorly differentiated tumor cells. Ki-67 index is higher in epithelial dysplasias and OSCC than in morphologically normal oral epithelium.