The c-Jun and JunB transcription factors facilitate the transit of classical Hodgkin lymphoma tumour cells through G(1)

Classical Hodgkin Lymphoma (cHL) is primarily a B cell lymphoid neoplasm and a member of the CD30-positive lymphomas. cHL and the other CD30-positive lymphomas are characterized by the elevated expression and/or constitutive activation of the activator protein-1 (AP-1) family transcription factors, c-Jun and JunB; however, the specific roles they play in the pathobiology of cHL are unclear. In this report we show that reducing either c-Jun or JunB expression with short-hairpin RNAs (shRNAs) reduced the growth of cHL cell lines in vitro and in vivo, primarily through impairing cell cycle transition through G(1). We further investigated the effect of c-Jun and JunB knock-down on proliferation in another CD30-positive lymphoma, anaplastic lymphoma kinase-positive, anaplastic large cell lymphoma (ALK+ ALCL). We found that JunB knock-down in most ALK+ ALCL cell lines examined also resulted in reduced proliferation that was associated with a G(0)/G(1) cell cycle defect. In contrast, c-Jun knock-down in multiple ALK+ALCL cell lines had no effect on proliferation. In summary, this study directly establishes that both c-Jun and JunB play roles in promoting HRS cell proliferation. Furthermore, we demonstrate there are similarities and differences in c-Jun and JunB function between cHL and ALK+ ALCL.