De novo programmed cell death in oral cancer.

Division of Laboratory Medicine, Regional Cancer Centre, Thiruvananthapuram, Kerala State, India.
Histopathology (Impact Factor: 2.86). 04/1999; 34(3):241-9. DOI:10.1046/j.1365-2559.1999.00575.x
Source: PubMed

ABSTRACT The importance of programmed cell death or apoptosis in the maintenance of tissue homoeostasis and the pathogenesis of oral cancer was analysed in relation to apoptosis regulatory proteins, tissue proliferation and tumour histology.
The extent of apoptosis was defined by morphological criteria and the TUNEL (terminal deoxy nucleotidyl transferase-mediated dUTP biotin nick end labelling) assay. p53, bax, bcl-2 and cyclin D1 expression was evaluated by immunocytochemistry. The presence of mutant p53 was analysed using a mutant p53-specific ELISA. An inverse correlation was observed between TUNEL reactivity and histology of the lesion (r = -0.555, P = 0.0001). There was also correlation between TUNEL reactivity and immunoreactivity of apoptosis regulatory proteins. p53 (r = 0.641, P = 0.00023), bcl-2 (r = -0.642, P = 0.00014) and bax (r = 0.651, P = 0.00002). The presence of mutant p53 protein showed an inverse correlation to the extent of apoptosis (r = - 0.301, P = 0.00063). Significant correlation was evident between the bax/bcl-2 ratio and TUNEL (r = 0.652, P = 0.00001) as well as between cyclin D1 and TUNEL reactivity (r = 0.577, P = 0.00001).
Results from this study suggest that apoptosis decreases as histological abnormality increases. Apoptotic regulatory proteins are also altered in a histologically dependent manner. Deregulated proliferation occurs simultaneously with decreased apoptosis during tumour progression in the oral mucosa.

0 0
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: Oropharyngeal squamous cell carcinomas (OSCC) constitute about 5% of all cancers in the western world and the incidence and mortality rates of this tumor have shown little improvement over the last 30 years. Molecular targeted therapy, a promising strategy for the treatment of OSCC and other cancers, requires the understanding of specific molecular events of carcinogenesis and the different pathological, partly interrelated pathways. Extended knowledge of the prognostic or predictive value of molecular biomarkers in oropharyngeal cancer is necessary to allow a better characterization and classification of the tumor, improve the appraisal of clinical outcome and help to specify individual multimodal therapy with increased efficiency. This work affords an updated summary regarding recent data about tissue biomarkers in patients with OSCC, based on the six essential hallmarks of cancer described by Hanahan and Weinberg (Cell 100(1):57-70, 2000) providing the characterization of a malignant cell.
    Archives of Oto-Rhino-Laryngology 01/2011; 268(1):5-16. · 1.29 Impact Factor
  • [show abstract] [hide abstract]
    ABSTRACT: Premalignant/potentially malignant-oral lesions and conditions such as oral submucous fibrosis are known to transform into oral cancer. The malignant transformation is often associated with changes at the genetic level that in turn is reflected by the altered expression of proteins related to cell cycle, proliferation, and apoptosis. To evaluate the expression of p53, Ki67 (MIB), bcl2, and bax in oral submucous fibrosis and oral squamous cell carcinoma. To assess the immunohistochemical expression of p53, Ki67 (MIB), bcl2, and bax in 50 cases of oral submucous fibrosis (OSF) and ten each of normal and oral squamous cell carcinoma (OSCC). The labeling indices (LI) of OSF and OSCC were comparable for p53 and Ki67.The p53 LI ranged from 7.9 to 71.9 in OSF and 65.2 to 85.9 in OSCC, and for Ki67 it ranged from 4.39 to 43.23, 18.35 to 42.33, respectively. The p53, Ki67, and bax profiles of OSF and OSCC were altered compared to the normal and these markers could be used as surrogate markers of malignant transformation in OSF.
    Journal of Oral and Maxillofacial Pathology 05/2011; 15(2):148-53.
  • Source
    [show abstract] [hide abstract]
    ABSTRACT: In vitro cell culture experiments with primary cells have reported that cell proliferation is retarded in the presence of ambient compared to physiological O₂ levels. Cancer is primarily a disease of aberrant cell proliferation, therefore, studying cancer cells grown under ambient O₂ may be undesirable. To understand better the impact of O₂ on the propagation of cancer cells in vitro, we compared the growth potential of a panel of ovarian cancer cell lines under ambient (21%) or physiological (3%) O₂. Our observations demonstrate that similar to primary cells, many cancer cells maintain an inherent sensitivity to O₂, but some display insensitivity to changes in O₂ concentration. Further analysis revealed an association between defective G2/M cell cycle transition regulation and O₂ insensitivity resultant from overexpression of 14-3-3 σ. Targeting 14-3-3 σ overexpression with RNAi restored O₂ sensitivity in these cell lines. Additionally, we found that metastatic ovarian tumors frequently overexpress 14-3-3 σ, which in conjunction with phosphorylated RB, results in poor prognosis. Cancer cells show differential proliferative sensitivity to changes in O₂ concentration. Although a direct link between O₂ insensitivity and metastasis was not determined, this investigation showed that an O₂ insensitive phenotype in cancer cells to correlate with metastatic tumor progression.
    PLoS ONE 01/2011; 6(1):e15864. · 3.73 Impact Factor