Spontaneous apoptosis in laryngeal squamous cell carcinoma is independent of bcl-2 and bax protein expression.

bcl-2 and bax genes are known to be involved in the control of apoptotic cell death, an important mechanism of growth regulation that influences the biologic behavior of tumors. The aim of the current study was to investigate the relationship of bcl-2 and bax expression to the rate of spontaneous apoptosis in laryngeal carcinomas, and to assess its relations to clinicopathologic features of tumors. Immunohistochemical analyses for bcl-2 and bax were performed on paraffin embedded tissue sections from 134 primary laryngeal squamous cell carcinomas. To visualize apoptotic cells, the nick end labeling method was used. The proliferative activity of tumors was analyzed by determination of mitotic indices. bcl-2 immunoreactivity was positively correlated with tumor grade (P < 0.00001), high T category (P < 0.02), metastatic involvement of cervical lymph nodes (P < 0.003), and supraglottic or subglottic location of primary tumors (P < 0.00005). An inverse relation was found between bcl-2 and bax expression (P < 0.004). The frequency of spontaneous apoptosis was closely associated with mitotic activity (P < 0.0004) but appeared to be unrelated to protein levels of bcl-2 or bax as well as to bcl-2:bax ratios. The results of this study point to the significance of cell proliferation as a major determinant of the rate of spontaneous apoptosis in laryngeal carcinomas. The bcl-2:bax expression ratio obviously does not affect the incidence of apoptosis, but it may be considered as a marker of disease progression and poor prognosis.

Jäckel MC ，Dorudian MA ，Marx D ，Brinck U ，Schauer A ，Steiner W ... -  《CANCER》

Prognostic significance of p53/bcl-2 co-expression in patients with laryngeal squamous cell carcinoma.

The p53, bcl-2, and bax genes are known to be involved in control of cell cycle progression and regulation of apoptotic cell death. Although they are frequently altered in laryngeal squamous cell carcinoma, their clinical relevance is not yet fully understood. In the present study, individual and combined expressions of these genes were related with patient survival as well as with proliferative and apoptotic activity. Retrospective study. Paraffin-embedded tissue sections of 88 laryngeal squamous cell carcinomas that were diagnosed and treated between 1986 and 1996 were investigated for p53, bcl-2, and bax protein expression by immunohistochemistry. Apoptotic cells were visualized using the nick end labeling method. To assess proliferative activity of tumors, mitotic indices were determined. Age of patients, advanced disease (stages HI and IV), high mitotic activity, positive bcl-2 expression, high level of p53 expression, and p53/bcl-2 co-expression were significantly associated with shortened overall survival in univariate analysis. In multivariate analysis, only age and p53/bcl-2 co-expression had independent prognostic value. Other combinations of genes, i.e., bcl-2-to-bax and p53-to-bax ratios, were not associated with patient outcome. A significant positive correlation was found between apoptotic and mitotic activity. However, protein levels of p53, bcl-2, and bax were unrelated to proliferation and apoptosis of tumor cells. The co-expression of p53/bcl-2 was an independent predictor of patient outcome and had a prognostic value superior to both parameters considered separately. The rate of apoptosis mainly counterbalanced proliferative activity but appeared not to be significantly influenced by p53, bcl-2, and bax.

Jäckel MC ，Sellmann L ，Dorudian MA ，Youssef S ，Füzesi L ... -  《LARYNGOSCOPE》

[The expression and significance of bcl-2 and bax in each phase of the cell cycle in laryngeal carcinoma].

Chen WL ，Guo XF ，Quan CS ，Luan XY ... -  《-》

Expression of p53 protein and the apoptotic regulatory molecules Bcl-2, Bcl-XL, and Bax in locally advanced squamous cell carcinoma of the lung.

Bcl-2 family of proteins plays a critical role in the regulation of apoptosis. This pathway may be dysregulated leading to an altered ratio of pro- and anti-apoptotic molecules, hence rendering cells resistant to chemotherapy. The objective of this study was to understand the role of Bcl-2 family members in mediation of apoptosis in squamous cell carcinoma of the lung. Bronchoscopically obtained lung biopsies from 30 cases of histologically proven squamous cell carcinoma of the lung in stage III were assessed for the expression of Bcl-2, Bcl-XL, and Bax at the mRNA and protein levels by semi-quantitative reverse transcription (RT-PCR) and immunohistochemistry. The apoptotic index (AI) was determined by the TUNEL assay. The AI ranged from <0.1 to 6.0% with a median of 1.3%. Bcl-2/Bax transcript ratio ranged from 1.5 to 4.5 and Bcl-XL/Bax from 1.3 to 4.0 indicating increased levels of anti-apoptotic molecules at the transcript levels. There was no correlation of the mRNA levels to the apoptotic index. (Wilcoxon-signed rank test.) Immunohistochemistry for proteins revealed that majority of the tumors were Bax predominated. p53 protein immunohistochemical expression was present in 66% cases. The apoptotic index correlated with Bax expression (P < 0.05; Wilcoxon-signed rank test and chi-square test) but not with Bcl-2, Bcl-XL or p53 levels. There was a positive association of p53 with Bax expression. The results of this study indicate that in locally advanced squamous cell carcinoma of the lung, Bax protein is up regulated and determines the level of apoptosis.

Shabnam MS ，Srinivasan R ，Wali A ，Majumdar S ，Joshi K ，Behera D ... -  《LUNG CANCER》

Expression of Bcl-2 family proteins in advanced laryngeal squamous cell carcinoma: correlation with response to chemotherapy and organ preservation.

Induction chemotherapy and definitive radiation therapy in advanced laryngeal cancer has been shown to achieve survival rates that are similar to total laryngectomy and postoperative radiation therapy. In patients with advanced laryngeal cancer, quality of life can be significantly enhanced by treatment regimens that preserve the larynx. However, which patients will respond best to organ preservation protocols remains unknown. The Bcl-2 family proteins are involved in control of apoptosis and, potentially, tumor response to chemotherapy. Retrospective analysis of immunohistochemical tumor characteristics and clinical outcome. To determine whether Bcl-2 family proteins were predictive of successful organ preservation, immunohistochemical analysis of tissue specimens from 47 patients with advanced laryngeal cancer from the U.S. Department of Veterans Affairs Cooperative Study Program (VA CSP-268) were evaluated for the expression of Bcl-2, Bcl-X(L), and Bax protein expression. Tumor response was classified as either complete or partial/nonresponse after induction chemotherapy. Protein expression was correlated with tumor response, organ preservation, and overall patient survival. The Bcl-2 protein was expressed at high levels in only 15% of specimens, but five of seven tumors with high Bcl-2 showed complete response (P = .10). The majority of tumors expressed high levels of Bcl-X(L) (74%). Reduced expression of Bcl-X(L) was associated with a complete response (P = .143) and with larynx preservation (P = .06). Most patients (81%) had increased levels of Bax expression. Reduced expression of Bax was associated with a complete response rate (P = .074), but there was no correlation between Bax expression and larynx preservation. The findings indicate that laryngeal cancer cells typically produce high levels of only one of the apoptosis protective proteins, Bcl-2 or Bcl-X(L). Prospective studies of larger numbers of patients are under way to determine whether Bcl-X(L) expression will be a useful marker predicting larynx preservation.

Trask DK ，Wolf GT ，Bradford CR ，Fisher SG ，Devaney K ，Johnson M ，Singleton T ，Wicha M ... -  《LARYNGOSCOPE》