Expression of matrix metalloproteinase-9 (gelatinase B) in benign, premalignant and malignant laryngeal lesions.

The matrix metalloproteinases (MMPs) are a family of proteolytic zinc-containing enzymes, which are responsible for the breakdown of the extracellular matrix components in pathological and physiological conditions. They are involved in basement membrane disruption, stroma and blood vessel penetration, metastasis and more recently there is evidence that they participate in tumor growth and angiogenic events. Matrix metalloproteinase 2 and 9 (MMP 2 and 9) belong to the gelatinases, a subgroup of MMPs, and have the capacity to degrade the triple helix type IV collagen of basal lamina of the basement membrane. With the present study, we tried to demonstrate the expression of MMP-9 immunohistochemically, comparatively in benign, premalignant and malignant lesions of the larynx. We studied 154 laryngeal lesions including 55 squamous cell carcinomas, 8 in situ carcinomas, 54 cases of dysplasia (of low and intermediate grade), 13 papillomas and 24 cases of keratosis. Overexpression of MMP 9 was observed in 74.4% and 50% in invasive and in situ squamous cell carcinomas respectively. In dysplastic cases, in papillomas and in keratoses the percentage of overexpression was 62.9%, 61.53% and 54.16% respectively and the expression of MMP-9 was significantly higher in invasive squamous cell carcinomas compared to dysplasias (p=0.000004). Also significantly higher was the expression of MMP-9 in dysplastic cases compared to papillomas (p=0.023). The MMP-9 expression was related neither to survival nor to the other available clinicopathological parameters (tumor size, grade, clinical stage, lymph node status and patient age). In conclusion, our study indicates that the expression of MMP-9 is up-regulated in a stepwise fashion, with two main steps, the first one, when a dysplastic lesion evolves and the next one, when the dysplasia progresses to invasive carcinoma.

Expression of cyclin-dependent kinases inhibitors p21(WAF1) and p27(KIP1) in benign, premalignant and malignant laryngeal lesions. correlation with cell cycle regulatory proteins.

BACKGROUND: Cell cycle progression and transition of cells from the first gap phase (G1) to the DNA replication phase (S) depend on a finely tuned balance between the levels of cyclins, cyclin-dependent kinases (CDKs) and cyclin-dependent kinase inhibitors (CDKIs). MATERIALS AND METHODS: We analyzed 57 squamous cell invasive carcinomas of the larynx, 10 in situ carcinomas, 56 cases of dysplasia, 11 papillomas and 26 keratosis. We investigated: a) the immunohistochemical expression of CDKIs, p21 and p27, b) any possible relation between normal and abnormal immunoprofiles of these proteins and p53 protein and proliferation status as determined by the expression of Ki67 and PCNA, and c) their presence in pre-malignant and malignant laryngeal lesions. RESULTS: Expression of p21 and p27 was observed in 58.9% and 89.5% of the laryngeal carcinomas, respectively. High levels of p21 were significantly correlated with increased cyclin D (p=0.001), cyclin E (p<0.001) and Ki67 (p<0.001), while increased expression levels of p27 were associated with p53 accumulation (p=0.02) and with increased proliferation status as expressed by Ki67 (p=0.05). CONCLUSION: Due to the increased expression levels of CDKIs in laryngeal carcinomas, we suggest the existence of a mechanism by which tumor cells tolerate the inhibitory effect of these proteins on cell cycle progression.