PURPOSE: To investigate the relationship between apoptotic cell death, proliferative activity, and the expression of apoptosis regulating proteins in rectal cancer prior to and after radiochemotherapy. MATERIALS AND METHODS: In 32 patients dispositioned to receive preoperative radiochemotherapy for locally advanced rectal carcinoma, pretherapy biopsies and the final resected specimen after radiochemotherapy were available for analyses. Apoptotic cells were identified and quantified using in situ end labeling (ISEL) technique. The expression of the bax protein was assessed immunohistochemically. Additionally, double immunostaining was performed for apoptotic cells and bax expression. The proliferative activity was determined by immunohistochemical assessment of the Ki67 (MIB-1) and the proliferating cell nuclear antigen (PCNA). p53- and bcl-2 expression was analyzed immunohistochemically. A clinical-to-pathologic downstaging after radiochemotherapy was achieved in 25 of 32 patients (78%). During follow-up, tumor recurrence was observed in six cases. In one case, no residual tumor was detected after radiochemotherapy. RESULTS: After radiochemotherapy, the apoptotic index increased significantly in almost every case examined. In contrast, the proliferative activity was significantly decreased in resected specimens as compared to biopsies. Bax immunostaining was detected in 12/31 (39%) biopsies and in 26/31 (84%) resected specimens. In the resected specimen, significantly more apoptotic cells that were bax-positive were found than in biopsies. Bcl-2 immunostaining occurred in 15/31 biopsies and 12/31 resected specimens, respectively. Tumors that were immunohistochemically negative for p53 (20/31 [65%]) generally exhibited a higher apoptotic index and a high expression level of bax than p53-positive tumors (11/31 [35%]). However, we did not find any correlation between the (pre- and post-therapeutic) rate of apoptosis or the level of bax expression and the degree of clinical-to-pathologic downstaging or the frequency of tumor recurrence. CONCLUSION: Our results indicate that radiochemotherapy is associated with an increase in bax expression and also in apoptotic cell death. The observation of higher rates of apoptosis and bax in p53-negative tumors suggests that p53 might be a possible regulating factor of apoptosis in rectal cancer.
PURPOSE: To investigate the relationship between apoptotic cell death, proliferative activity, and the expression of apoptosis regulating proteins in rectal cancer prior to and after radiochemotherapy. MATERIALS AND METHODS: In 32 patients dispositioned to receive preoperative radiochemotherapy for locally advanced rectal carcinoma, pretherapy biopsies and the final resected specimen after radiochemotherapy were available for analyses. Apoptotic cells were identified and quantified using in situ end labeling (ISEL) technique. The expression of the bax protein was assessed immunohistochemically. Additionally, double immunostaining was performed for apoptotic cells and bax expression. The proliferative activity was determined by immunohistochemical assessment of the Ki67 (MIB-1) and the proliferating cell nuclear antigen (PCNA). p53- and bcl-2 expression was analyzed immunohistochemically. A clinical-to-pathologic downstaging after radiochemotherapy was achieved in 25 of 32 patients (78%). During follow-up, tumor recurrence was observed in six cases. In one case, no residual tumor was detected after radiochemotherapy. RESULTS: After radiochemotherapy, the apoptotic index increased significantly in almost every case examined. In contrast, the proliferative activity was significantly decreased in resected specimens as compared to biopsies. Bax immunostaining was detected in 12/31 (39%) biopsies and in 26/31 (84%) resected specimens. In the resected specimen, significantly more apoptotic cells that were bax-positive were found than in biopsies. Bcl-2 immunostaining occurred in 15/31 biopsies and 12/31 resected specimens, respectively. Tumors that were immunohistochemically negative for p53 (20/31 [65%]) generally exhibited a higher apoptotic index and a high expression level of bax than p53-positive tumors (11/31 [35%]). However, we did not find any correlation between the (pre- and post-therapeutic) rate of apoptosis or the level of bax expression and the degree of clinical-to-pathologic downstaging or the frequency of tumor recurrence. CONCLUSION: Our results indicate that radiochemotherapy is associated with an increase in bax expression and also in apoptotic cell death. The observation of higher rates of apoptosis and bax in p53-negative tumors suggests that p53 might be a possible regulating factor of apoptosis in rectal cancer.
Authors: Venkat R Katkoori; Catalina Suarez-Cuervo; Chandrakumar Shanmugam; Nirag C Jhala; Tom Callens; Ludwine Messiaen; James Posey; Harvey L Bumpers; Sreelatha Meleth; William E Grizzle; Upender Manne Journal: J Gastrointest Oncol Date: 2010-12
Authors: B Michael Ghadimi; Marian Grade; Michael J Difilippantonio; Sudhir Varma; Richard Simon; Cristina Montagna; Laszlo Füzesi; Claus Langer; Heinz Becker; Torsten Liersch; Thomas Ried Journal: J Clin Oncol Date: 2005-03-20 Impact factor: 44.544
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Authors: M J E M Gosens; R C Dresen; H J T Rutten; G A P Nieuwenhuijzen; J A W M van der Laak; H Martijn; I Tan-Go; I D Nagtegaal; A J C van den Brule; J H J M van Krieken Journal: Ann Oncol Date: 2008-07-29 Impact factor: 32.976
Authors: Marian Grade; Jochen Gaedcke; Danny Wangsa; Sudhir Varma; Jaje Beckmann; Torsten Liersch; Clemens Hess; Heinz Becker; Michael J Difilippantonio; Thomas Ried; B Michael Ghadimi Journal: Cancer Genet Cytogenet Date: 2009-08