BCL-W is dispensable for the sustained survival of select Burkitt lymphoma and diffuse large B-cell lymphoma cell lines

Dysregulated expression of BCL-2 family proteins allows cancer cells to escape apoptosis. To counter this, BH3-mimetic drugs that target and inhibit select BCL-2 prosurvival proteins to induce apoptosis have been developed for cancer therapy. Venetoclax, which targets BCL-2, has been effective as therapy for patients with chronic lymphocytic leukemia, and MCL-1-targeting BH3-mimetic drugs have been extensively evaluated in preclinical studies for a range of blood cancers. Recently, BCL-W, a relatively understudied prosurvival member of the BCL-2 protein family, has been reported to be abnormally upregulated in Burkitt lymphoma (BL), diffuse large B-cell lymphoma (DLBCL), and Hodgkin lymphoma patient samples. Therefore, to determine if BCL-W would be a promising therapeutic target for B-cell lymphomas, we have examined the role of BCL-W in the sustained growth of human BL- and DLBCL-derived cell lines. We found that CRISPR/CAS9-mediated loss or short hairpin RNA-mediated knockdown of BCL-W expression in selected BL and DLBCL cell lines did not lead to spontaneous apoptosis and had no effect on their sensitivity to a range of BH3-mimetic drugs targeting other BCL-2 prosurvival proteins. Our results suggest that BCL-W is not universally required for the sustained growth and survival of human BL and DLBCL cell lines. Thus, targeting BCL-W in this subset of B-cell lymphomas may not be of broad therapeutic benefit

Mutant TRP53 exerts a target gene-selective dominant-negative effect to drive tumor development

Mutations in Trp53, prevalent in human cancer, are reported to drive tumorigenesis through dominant-negative effects (DNEs) over wild-type TRP53 function as well as neomorphic gain-of-function (GOF) activity. We show that five TRP53 mutants do not accelerate lymphomagenesis on a TRP53-deficient background but strongly synergize with c-MYC overexpression in a manner that distinguishes the hot spot Trp53 mutations. RNA sequencing revealed that the mutant TRP53 DNE does not globally repress wild-type TRP53 function but disproportionately impacts a subset of wild-type TRP53 target genes. Accordingly, TRP53 mutant proteins impair pathways for DNA repair, proliferation, and metabolism in premalignant cells. This reveals that, in our studies of lymphomagenesis, mutant TRP53 drives tumorigenesis primarily through the DNE, which modulates wild-type TRP53 function in a manner advantageous for neoplastic transformation

Supplementary Data Figure S7 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Figure S7 showing that complete removal of mutant TP53 in MDA-MB-231 cells does not impair survival and proliferation in culture</p

Supplementary Data Table S1 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Table S1 showing statistical analysis of differences in the numbers of human cancer cells in vitro with or without removal of mutant TP53</p

Supplementary Data Figure S9 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Figure S9 showing that complete removal of mutant TP53 in Rael-BL cells does not impair survival and proliferation in culture</p

Supplementary Data Figure S17 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Figure S17 showing that removal of mutant TP53 does not impact colony formation of human cancer cell lines in vitro</p

Supplementary Data Figure S16 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Figure S16 showing that removal of mutant TP53 does not impair in vivo tumor growth of human cancer lines even when limited numbers of cancer cells are transplanted</p

Supplementary Data Figure S19 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Figure S19 showing that removal of mutant TP53 does not impair the migration of human cancer cell lines in vitro</p

Supplementary Data Figure S17 from Loss-of-Function but Not Gain-of-Function Properties of Mutant TP53 Are Critical for the Proliferation, Survival, and Metastasis of a Broad Range of Cancer Cells

Supplementary Figure S17 showing that removal of mutant TP53 does not impact colony formation of human cancer cell lines in vitro</p