Molecular mechanism of the signaling pathway for execution of spontaneous apoptosis of human B-cell lymphoma

2001 Fiscal Year Final Research Report Summary

• Project/Area Number: 12670168
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Human pathology
• Research Institution: Fukushima Medical University
• Principal Investigator: ABE Masafumi Fukushima Medical University School of Medicine Professor, 医学部, 教授 (00045783)
• Co-Investigator(Kenkyū-buntansha): HASHIMOTO Yuko Fukushima Medical University School of Medicine Instructor, 医学部, 助手 (60305357) ; TASAKI Kazuhiro Fukushima Medical University School of Medicine Instructor, 医学部, 助手 (70244382) ; ONO Nobutaka Fukushima Medical University School of Medicine Instructor, 医学部, 助手 (80233584)
• Project Period (FY): 2000 – 2001
• Keywords: apoptosis / caspase / Bcl-2 family / TRAF / NF-kB / B-cell lymphoma

Research Abstract

We analyzed bcl-2 family molecules, caspase and TRF molecules using Western blot method and Northern blot method (ribonuclease protection assay) to elucidate the signaling pathway for execution of spontaneous apoptosis of HBL-9 cells. In addition, we examined the NF-kB activity in HBL-9 cells using electrophoretic mobility shift assay (EMSA) to investigate the relationship between NF-kB activation and TRAF molecules or bcl-2 molecules. HBL-9 cells showed the expression of caspase-2, caspase-3, caspase-7 and caspase-8 at the protein and gene (mRNA) levels, and the processing of those caspase molecules was demonstrated. HBL-9 cells displayed the gene expression (mRNA) of bcl-XL, bax, bad and bid and expression of Bax, Bad proteins but no expression of Bcl-2 and Bcl-XL proteins. HBL-9 cells expressed the mRNAs ofTRAF 1, TRAF 2, TRAF 3 and TRAF 4, and showed the expression of TRAF 2 and TRAF 3 proteins but no expression of TRAF 1 and TRAF 4 proteins. NF-kB activity was not detected.
Those data indicate the following on the molecular mechanism for the execution of spontaneous apoptosis of HBL-9 cells ;
1) At least four caspases (caspase-2, caspase-3, caspase-7 and caspase-8) are activated for the spontaneous apoptosis of HBL-9 cells, and an unknown upstream caspase of those caspases might play a role as a key caspase in the caspase cascade.
2) A signaling pathway, bcl-2 family - cytochrome C - Apaf-1 - caspase-9, is not associated with the execution of the spontaneous apoptosis of HBL-9 cells.
3) Disturbance of antiapoptotic mechanism involving lack of Bcl-2 and Bcl-XL molecules and inactivation of NF-kB can cause the induction of the spontaneous apoptosis of HBL-9 cells.