Activation of CD40 in Cervical Carcinoma Cells Facilitates CTL Responses and Augments Chemotherapy-Induced Apoptosis

Abstract

In this study, we describe the expression and function of CD40, a TNF receptor family member, in cervical carcinomas. CD40 was present at very low levels in normal cervical epithelium but was overexpressed in human papillomavirus-infected lesions and advanced squamous carcinomas of the cervix. The stimulation of CD40-positive cervical carcinoma cell lines with soluble CD40L (CD154) resulted in activation of the NF-κB and MAPK signaling pathways and up-regulation of cell surface markers and intracellular molecules associated with Ag processing and presentation. Concomitantly, the CD154-induced activation of CD40 in carcinoma cells was found to directly influence susceptibility to CTL-mediated killing. Thus, CD40 stimulation in cervical carcinoma cell lines expressing a TAP-dependent human papillomavirus 16 E6 Ag epitope resulted in their enhanced killing by specific CTLs. However, CD154 treatment of carcinoma cells expressing proteasome-dependent but TAP-independent Ags from the EBV-encoded BRLF1 and BMLF1 failed to increase tumor cell lysis by specific CTLs. Moreover, we demonstrate that chemotherapeutic agents that suppress protein synthesis and reverse the CD40-mediated dissociation of the translational repressor eukaryotic initiation factor 4E-binding protein from the initiation factor eukaryotic initiation factor 4E, such as 5-fluorouracil, etoposide, and quercetin, dramatically increase the susceptibility of cervical carcinoma cells to CD40L-induced apoptosis. Taken together, these observations demonstrate the functional expression of CD40 in epithelial tumors of the cervix and support the clinical exploitation of the CD40 pathway for the treatment of cervical cancer through its multiple effects on tumor cell growth, apoptosis, and immune recognition.

CD40 Stimulates a “Feed-Forward” NF-κB–Driven Molecular Pathway That Regulates IFN-β Expression in Carcinoma Cells

“…Thus, both CD40L and IFN-b confer negative effects on carcinoma growth by improving tumor cell immunogenicity (4,14,15) and triggering direct antiproliferative and proapoptotic properties (37)(38)(39)(40)(41). Both CD40L and type I IFNs also act on immune cells to augment Th1 cell responses, enhance expression of MHC class I molecules, and generate NK and T cellmediated cytotoxicity (reviewed in Refs.…”

“…The antiviral activity of CD40L has also been documented in the mouse (11), and increasing experimental and clinical evidence suggests that activation of the CD40 pathway could be exploited for cancer therapy (12,13). Indeed, the stimulation of tumor cells with CD40L induces the expression of components of the Ag presentation machinery required for the engagement of antitumor immune responses (14) through the sequential activation of NF-kB and its target, IRF1 (15). Interestingly, IRF1 participates in an autoregulatory loop in the context of type I IFN signaling in which IRF1 is both a target and a transcriptional activator of IFN-b (16,17).…”

A novel mechanism of CD40-induced apoptosis of carcinoma cells involving TRAF3 and JNK/AP-1 activation

“…15 The inability of control fibroblasts to mediate apoptosis in the presence of soluble CD40L or G28-5 antibody argues conclusively against any nonspecific effects, as suggested by others. 39 In B cells, CD40 initiates complex signaling cascades via direct interactions with the TRAFs. Differential TRAF binding induces specific receptor conformations and the degree of receptor crosslinking critically influences the 'molecular signature' of the CD40 stimulus.…”

HPV16 E629‐38‐specific T cells kill cervical carcinoma cells despite partial evasion of T‐cell effector function

“…This might result from insufficient TCR avidity and/or constraints on epitope generation imposed by inadequate endogenous antigen processing and presentation. 12 However, previous attempts to remedy such defects by treating cell lines with IFN-g 12 or triggering via CD40 25 were unsuccessful, unless accompanied by transfection with HPV16 E6. If epitope density was the only limiting factor, then it would be predicted that these carcinoma cells would not stimulate CD8…”