Studies of cellular retinol-binding protein (CRBP) in squamous-cell carcinomas of the head and neck region

Identification of guanylate-binding protein 1 as a potential oral cancer marker involved in cell invasion using omics-based analysis

Oral cavity squamous cell carcinoma (OSCC) is a devastating disease that accounts for 3% of all cancer cases diagnosed annually. OSCC is usually diagnosed at advanced clinical stages, resulting in poor outcomes. To identify effective biomarkers for improved OSCC diagnosis and/or management, we simultaneously analyzed the OSCC cell secretome and tissue transcriptome. Among the 19 candidates isolated, guanylate-binding protein 1 (GBP1) was selected for further validation using serum samples from OSCC patients and healthy controls. Notably, the serum level of GBP1 was higher in OSCC patients, compared to that in healthy controls. Immunohistochemical analysis further revealed GBP1 overexpression in OSCC tissues, compared with adjacent noncancerous epithelia. Importantly, the higher GBP1 level in OSCC tissue was associated with higher overall pathological stage, positive perineural invasion, and poorer prognosis. Moreover, GBP1 modulated the migration and invasion of OSCC cells in vitro. Our results collectively indicate that integrated analysis of the cancer secretome and transcriptome is a feasible strategy for the efficient identification of novel OSCC markers.

Increased expression of cellular retinol-binding protein 1 in laryngeal squamous cell carcinoma

PURPOSE

To investigate the genomic alterations in larynx carcinomas (LaCa) tissues and its prognostics values in predicting survival.

METHODS

To analyse the aberrations in the genome of LaCa patients, we used array comparative genomic hybridization in 19 human laryngeal tumour samples. DNA samples were also subjected to detect human papillomavirus (HPV) sequences by polymerase chain reaction (PCR). Copy number gain was confirmed by real-time PCR. The cellular retinol-binding protein 1 (CRBP-1) gene expression was also confirmed by immunohistochemistry assay on LaCa tissues. To identify prognostic feature, CRBP-1 gene gain was correlated to patient survival.

RESULTS

The most common gains were detected for CRBP-1 and EGFR genes, while DNA lost in RAF-1 gene. Immunohistochemistry assay was revealed strong expression of CRBP1 protein in those cases with CRBP-1 gene gain. The CRBP-1 gene gain and its expression correlated significantly with survival (P = 0.003). Cox regression analysis indicated that CRBP-1 expression level was a factor of survival (P = 0.008). HPV sequences were detected in 42% of the samples, and did not show any relationship with specific gene alterations.

CONCLUSION

Our data shows that CRBP-1 gene gain can be determined by immunohistochemistry on routinely processed tissue specimens, and could support as a potential novel marker for long-term survival in laryngeal squamous cell carcinoma.

Delivery of retinoid-based therapies to target tissues

Through its various metabolites, vitamin A controls essential physiological functions. Both naturally occurring metabolites and novel retinoid analogues have shown effectiveness in many clinical settings that include skin diseases and cancer, and in animal models of human conditions affecting vision. In this review, we analyze several potential retinoid-based therapies from the point of view of drug metabolism and transport to target tissues. We focus on the endogenous factors that affect the absorption, transport, and metabolism of retinoids by taking into account data obtained from the analysis of animal models that lack the enzymes or proteins involved in the storage and absorption of retinoids. We also discuss findings of toxicity associated with retinoids in an effort to improve the outcome of retinoid-based therapies. In this context, we review evidence that esterification of retinol and retinol-based drugs within target tissues provides one of the most efficient means to improve the absorption and to reduce the toxicity associated with pharmacological doses of retinoids. Future retinoid-based therapeutic strategies could involve targeted delivery mechanisms leading to lower toxicity and improved effectiveness of retinoids.

Oral precancer: preventive and medical approaches to management

Leukoplakias are among the most common potentially malignant oral lesions. Some are idiopathic, others are related to habits such as tobacco and/or alcohol use. Medical management includes reducing or abandoning these habits, increasing the intake of fruit and vegetables in the diet, and possibly the use of active agents. Retinoids, carotenoids and topical cytotoxic agents show promise, and newer therapies are on the horizon.

Cellular retinol-binding protein in mucosa, in benign and malignant non-squamous cell tumours of the head and neck

The measurement and localisation of cellular retinol-binding protein (CRBP), in samples of normal oral mucosa, larynx papilloma and malignant lymphoma of the oropharynx, was performed with a radioimmunoassay and immunolocalisation techniques. As compared with CRBP concentration in normal mucosa, those in laryngeal papilloma were significantly higher, but those of malignant lymphoma were similar. CRBP concentrations were highest in maturing keratinocytes within the prickle cell layers of normal mucosa and in laryngeal papillomas, as estimated on the basis of immunoreactivity to CRBP. The retinyl palmitate concentrations in extracts of oral mucosa correlated to the retinol concentrations, both in plasma and mucosal extracts, but not to the CRBP content in mucosal extracts. The immunolocalisation of a cellular retinoic acid-binding protein (CRABP) like antigen in normal oral mucosa showed much the same picture with strongest staining of the maturing keratinocytes of the prickle cell layers.

Quantitation and localization of cellular retinol-binding protein in squamous-cell carcinomas of the cervix uteri and of the oral cavity

The concentration of cellular retinol-binding protein (CRBP) was determined by radioimmunoassay in biopsies of normal mucosa and squamous-cell carcinomas of cervix uteri from 30 women. The tumour tissues contained significantly higher concentrations of CRBP (median = 120 micrograms/g protein) than normal mucosa (median = 32 micrograms/g protein). The distribution of CRBP in normal mucosa and squamous-cell carcinomas from cervix uteri and from oral cavity was evaluated by immunohistochemical techniques. In tissue sections of normal epithelium from the cervix uteri and the oral cavity, the maturing keratinocytes in the prickle-cell layers were moderately or strongly stained when antiserum against CRBP was used, while the proliferating cells in the basal-cell layer were stained only lightly if at all. Squamous-cell carcinomas of the cervix uteri and the oral cavity presented much the same picture. The observed difference in CRBP concentration between squamous-cell carcinomas and normal squamous-cell mucosa may therefore be more quantitative than qualitative.

Retinoid-binding proteins in human oral mucosa

Vitamin A affects epithelial differentiation and growth via at least 3 different binding proteins. The specific delivery of extracellular retinol to target cells is performed by plasma retinol-binding protein (RBP) while cellular retinol- and retinoic acid-binding proteins (CRBP and CRABP) are implicated in the cellular action of the 2 natural retinoids. We have studied the levels of these 3 binding proteins by gel filtration and polyacrylamide electrophoresis in human oral mucosa, epithelium and chorion and compared it to those found in keratinizing human epidermis. The levels of CRABP in oral epithelium were markedly higher (about 4 times) than that of epidermis whereas CRBP was in a similar amount in epithelium chorion, dermis and epidermis. RBP with preserved affinity for retinol, was present in the epithelium of oral mucosa whereas only degraded RBP was detected in epidermis. These results suggest (i) a higher specific retinol delivery and (ii) a distinct cellular metabolism of retinoic acid in the oral epithelium as compared with epidermis. Since cornification occurs when keratinocytes are deprived of retinol, it might be that our observations are linked to the absence of cornification in the human oral mucosa. Further, high levels of CRABP in mucosal epithelium might have therapeutical implications because the synthetic retinoids used in human therapy bind to CRABP.