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Int J Colorectal Dis. 2004 Nov;19(6):538-44. Epub 2004 Apr 14.

BAX and caspase-5 frameshift mutations and spontaneous apoptosis in colorectal cancer with microsatellite instability.

Author information

1
2nd Department of Medicine and Senckenberg Center of Pathology, Johann Wolfgang Goethe University Medical Center, Theodor-Stern-Kai 7, 60590 Frankfurt a.M., Germany. trojan@em.uni-frankfurt.de.

Abstract

BACKGROUND AND AIMS:

Hereditary nonpolyposis colorectal cancer (HNPCC) and a subset of sporadic colorectal cancers are characterized by microsatellite instability (MSI) and inactivating frameshift mutations of target genes. Inactivation of BAX, caspase-5 ( cas-5), and other genes coding for pro-apoptotic proteins might contribute to tumor progression by enhancing escape from apoptosis. The aim of this study was to further characterize the role of BAX and cas-5 inactivation for spontaneous apoptosis.

METHODS:

Twenty-five colorectal cancers with MSI were analyzed for frameshift mutations in the BAX (G)8 and cas-5 (A)10 tract by fluorescence PCR, cloning, and sequencing. The rate of spontaneous apoptosis was examined by in situ DNA nick end-labeling. The results were compared with 25 stage-matched microsatellite stable (MSS) colorectal cancers.

RESULTS:

In colorectal cancer with MSI frameshift mutations in BAX and cas-5 were present in 16 of 25 (64%) and in 12 of 25 (48%) tumors, respectively, whereas neither mutant BAX nor cas-5 alleles were detected in all stage-matched sporadic MSS colorectal cancer. Tumors with MSI showed a higher apoptotic rate than MSS tumors (2.5+/-1.0 vs. 2.1+/-0.7; p <0.05), whereas the presence of BAX or cas-5 frameshift mutations had only minor influence on this finding (2.4+/-1.1% and 2.5+/-0.9%, respectively).

CONCLUSION:

Mismatch-repair deficiency itself is associated with increased spontaneous apoptosis, not further accelerated by either inactivating BAX or cas-5 frameshift mutations.

PMID:
15088110
DOI:
10.1007/s00384-004-0597-1
[Indexed for MEDLINE]

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