Characterization of NF- B Expression in Hodgkin's Disease: Inhibition of Constitutively Expressed NF- B Results in Spontaneous Caspase-Independent Apoptosis in Hodgkin and Reed-Sternberg Cells

• Published in: Modern pathology Vol. 14; no. 4; pp. 297 - 310
• Main Authors: Izban, Keith F, Ergin, Melek, Huang, Qin, Jian-zhong, Qin, Martinez, Robert L, Schnitzer, Bertram, Ni, Hongyu, Nickoloff, Brian J, Alkan, Serhan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Limited 01.04.2001
• Subjects: Adenovirus; Adenoviruses; Apoptosis; Cells; Cytokines; Genes; Lymphocytes; Lymphoma; Pathology; Proteins; Transcription factors; Tumor necrosis factor-TNF
• ISSN: 0893-3952; 1530-0285
• DOI: 10.1038/modpathol.3880306

Although the neoplastic cells of classical Hodgkin's disease (CHD) demonstrate high levels of constitutively active nuclear NF-kappaB, the precise physiologic and clinical significance of NF-kappaB expression is currently undefined. Expression of active NF-kappaB p65(Rel A) was evaluated in patient samples of CHD and nodular lymphocyte predominance Hodgkin's disease. The action of the chemical NF-kappaB inhibitors gliotoxin and MG132 and the effect of NF-kappaB inhibition utilizing an adenovirus vector carrying a dominant-negative IkappaBalpha mutant (Ad5IkappaB) were then demonstrated in CHD cell lines (L428, KMH2, and HS445). Hodgkin and Reed-Sternberg (HRS) cells from all patient and cell line specimens showed strong immunopositivity for active p65(Rel A). Expression was also seen in lymphocytic/histiocytic cells from all cases of nodular lymphocyte predominance Hodgkin's disease. After chemical NF-kappaB inhibition, p65(Rel A) was significantly reduced in nuclear extracts from cultured HRS cells as revealed by electrophoretic mobility shift assays. Furthermore, chemical NF-kappaB inhibition resulted in time- and concentration-dependent apoptosis in HRS cells. With the exception of MG132-induced apoptosis in HS445, apoptosis by chemical NF-kappaB inhibition was not significantly altered by preincubation with various caspase inhibitors (z-DQMD-FMK, z-DEVD-FMK, z-VAD-FMK, z-VEID-FMK, and z-IETD-FMK). Regardless of the chemical inhibitor used, no significant change in caspase-3 functional activity was found in CHD cell lines. HRS cells infected with Ad5IkappaB also showed a marked increase in spontaneous apoptosis compared with wild type adenovirus-infected and control cells. Overall, the inhibition of active NF-kappaB in HRS cells resulting in spontaneous caspase-independent apoptosis demonstrates a critical role for NF-kappaB in HRS cell survival and resistance to apoptosis.