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

Abstract

Although the neoplastic cells of classical Hodgkin's disease (CHD) demonstrate high levels of constitutively active nuclear NF-B, the precise physiologic and clinical significance of NF-B expression is currently undefined. Expression of active NF-B p65(Rel A) was evaluated in patient samples of CHD and nodular lymphocyte predominance Hodgkin's disease. The action of the chemical NF-B inhibitors gliotoxin and MG132 and the effect of NF-B inhibition utilizing an adenovirus vector carrying a dominant-negative IB␣ mutant (Ad5IB) 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-B inhibition, p65(Rel A) was significantly reduced in nuclear extracts from cultured HRS cells as revealed by electrophoretic mobility shift assays. Furthermore, chemical NF-B inhibition resulted in time-and concentration-dependent apoptosis in HRS cells. With the exception of MG132-induced apoptosis in HS445, apoptosis by chemical NF-B 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 Ad5IB also showed a marked increase in spontaneous apoptosis compared with wild type adenovirus-infected and control cells. Overall, the inhibition of active NF-B in HRS cells resulting in spontaneous caspase-independent apoptosis demonstrates a critical role for NF-B in HRS cell survival and resistance to apoptosis.

Lymphocyte-rich classical Hodgkin's lymphoma: distinctive tumor and microenvironment markers

“…10 NF-kB activation is considered to be an important survival factor for mononuclear Hodgkin's cells and multinucleated Reed-Sternberg cells in classical Hodgkin's lymphoma, whereby the inactivation of factor NF-kB in Hodgkin's lymphoma cell lines leads to the apoptosis of neoplastic cells. 13,14 Different expression patterns of NF-kB subunits and related molecular factors have been shown in classical Hodgkin's lymphoma and nodular lymphocyte-predominant Hodgkin's lymphoma, with c-Rel protein, Rel-B, p-50, TRAF1, and MUM-1 being significantly more frequently expressed in the former. Our results are similar, supporting the hypothesis that there is a low or null degree of NFkB activation in nodular lymphocyte-predominant Hodgkin's lymphoma.…”

IκBα independent induction of NF-κB and its inhibition by DHMEQ in Hodgkin/Reed-Sternberg cells

“…Furthermore, inhibition of NF-kB by gliotoxin, MG132, and PS341 is only one of the results of their activities as proteasome inhibitors. 28,29 Arsenic also alters a variety of enzymatic activities because of reactivity with sulfhydryl groups. 30 The unique properties of DHMEQ appear to minimize adverse effects on normal cells.…”

“…However, their specificity for the NF-kB pathway appears to be relatively low when compared with that of DHMEQ. [28][29][30] The target of DHMEQ resides downstream of targets of gliotoxin, MG132, arcenic and PS341. Furthermore, inhibition of NF-kB by gliotoxin, MG132, and PS341 is only one of the results of their activities as proteasome inhibitors.…”

Recombinant adenovirus-mediated cytotoxic gene therapy of lymphoproliferative disorders: is CAR important for the vector to ride?

“…22 More recently, other investigators have explored the use of adenovirus-mediated cytotoxic gene therapy with an approach different from those previously discussed. 23,24 The inhibition of the nuclear factor k B (NFkB) by adenovirus-mediated expression of dominant negative inhibitor k Ba (Ad5IkB) caused apoptosis in U266 cells, derived from MM. 23 In another study, the same results were obtained with the same Ad5IkB in cell derived from HD.…”

“…23 In another study, the same results were obtained with the same Ad5IkB in cell derived from HD. 24 Ultimately, some gene products derived from the adenovirus genome may induce apoptosis as it has been recently reviewed. 25 In recent years, several investigators have considered to modify the genetics of adenovirus particles to create mutants of the E1A or E1B region of the viral genome that complement the host proteins involved in the regulation of the cell cycle or apoptosis.…”