Methionine Deprivation Induces a Targetable Vulnerability in Triple-Negative Breast Cancer Cells by Enhancing TRAIL Receptor-2 Expression

Abstract

Purpose Many neoplasms are vulnerable to methionine deficiency by mechanisms that are poorly understood. Because gene profiling studies have revealed that methionine depletion increases TNF-related apoptosis-inducing ligand receptor-2 (TRAIL-R2) mRNA, we postulated that methionine stress sensitizes breast cancer cells to proapoptotic TRAIL-R2 agonists. Experimental Design Human triple (ER/PR/HER2)-negative breast carcinoma cell lines were cultured in control or methionine-free media. The effects of methionine depletion on TRAIL receptor expression and sensitivity to chemotherapy or a humanized agonistic TRAIL-R2 monoclonal antibody (lexatumumab) were determined. The melanoma-associated antigen MAGED2 was silenced to delineate its functional role in sensitizing TNBC cells to methionine stress. An orthotopic TNBC model was utilized to evaluate the effects of dietary methionine deficiency, lexatumumab or the combination. Results Methionine depletion sensitized TNBC cells to lexatumumab-induced caspase activation and apoptosis by increasing TRAIL-R2 mRNA and cell surface expression. MCF-10A cells transformed by oncogenic H-Ras, but not untransformed cells, and matrix-detached TNBC cells were highly sensitive to the combination of lexatumumab and methionine depletion. Proteomics analyses revealed that MAGED2, which has been reported to reduce TRAIL-R2 expression, was suppressed by methionine stress. Silencing MAGED2 recapitulated features of methionine deprivation, including enhanced mRNA and cell surface expression of TRAIL receptors and increased sensitivity to TRAIL receptor agonists. Dietary methionine deprivation enhanced the antitumor effects of lexatumumab in an orthotopic metastatic TNBC model. Conclusion Methionine depletion exposes a targetable defect in TNBC cells by increasing TRAIL-R2 expression. Our findings provide the foundation for a clinical trial combining dietary methionine restriction and TRAIL-R2 agonists.

Metformin sensitizes triple-negative breast cancer to proapoptotic TRAIL receptor agonists by suppressing XIAP expression

“…Cell surface expression of TRAIL receptors (TRAIL-R1 and TRAIL-R2) was determined by flow cytometry using TRAIL-R1, TRAIL-R2, or control IgG1 mAb conjugated with allophycocyanin (BioLegend) as described previously [14].…”

“…Real-time PCR for TRAIL-R1, TRAIL-R2, and GAPDH was performed as described previously [14]. Primers for XIAP (forward 5-AGTGCCACGCAGTCTACAAA, …”

“…More recently, we have identified a novel nutritional intervention that selectively sensitizes breast cancer cells to TRAIL-R2 agonists [14]. Specifically, we demonstrated that depletion of the essential amino acid methionine metabolically primes breast cancer cells to respond to the agonistic TRAIL-R2 mAb lexatumumab by increasing cell surface expression of TRAIL-R2.…”

“…Specifically, we demonstrated that depletion of the essential amino acid methionine metabolically primes breast cancer cells to respond to the agonistic TRAIL-R2 mAb lexatumumab by increasing cell surface expression of TRAIL-R2. Moreover, dietary methionine restriction enhanced the antitumor activity of lexatumumab against mammary tumors and lung metastases in an orthotopic model of metastatic breast cancer [14]. Hence, methionine restriction metabolically primes breast cancer cells to targeted agents that activate cell death by exposing a targetable vulnerability, namely enhanced cell surface expression of TRAIL-R2.…”

A metabolomic approach to identifying platinum resistance in ovarian cancer

“…Studies have shown that methionine levels are directly involved in promoting proliferation of cancer cells [31] and in protecting the cancer cells against chemotherapeutic drugs like Fluorouracil [32]. Methionine deprivation has been shown to inhibit tumor cell growth in various cancers both in in vitro and in vivo models along with chemo-sensitizing cancer cells [33][34][35][36]. We observed decreased levels of methionine in resistant C200 cells, which could indicate its increased utilization ( Figure 3B), and could suggest the presence of 'methionine dependency' in the resistant cells.…”