Cervical cancer is responsible for 10–15% of cancer-related deaths in women worldwide1,2. The etiological role of infection with high-risk human papilloma viruses (HPV) in cervical carcinomas is well established3. Previous studies have implicated somatic mutations in PIK3CA, PTEN, TP53, STK11 and KRAS4–7 as well as several copy number alterations in the pathogenesis of cervical carcinomas8,9. Here, we report whole exome sequencing analysis of 115 cervical carcinoma-normal paired samples, transcriptome sequencing of 79 cases and whole genome sequencing of 14 tumor-normal pairs. Novel somatic mutations in 79 primary squamous cell carcinomas include recurrent E322K substitutions in the MAPK1 gene (8%), inactivating mutations in the HLA-B gene (9%), and mutations in EP300 (16%), FBXW7 (15%), NFE2L2 (4%) TP53 (5%) and ERBB2 (6%). We also observed somatic ELF3 (13%) and CBFB (8%) mutations in 24 adenocarcinomas. Squamous cell carcinomas had higher frequencies of somatic mutations in the Tp*C dinucleotide context than adenocarcinomas. Gene expression levels at HPV integration sites were significantly higher in tumors with HPV integration compared with expression of the same genes in tumors without viral integration at the same site. These data demonstrate several recurrent genomic alterations in cervical carcinomas that suggest novel strategies to combat this disease.
We assessed somatic alleles of six receptor tyrosine kinase genes mutated in lung adenocarcinoma for oncogenic activity. Five of these genes failed to score in transformation assays; however, novel recurring extracellular domain mutations of the receptor tyrosine kinase gene ERBB2 were potently oncogenic. These ERBB2 extracellular domain mutants were activated by two distinct mechanisms, characterized by elevated C-terminal tail phosphorylation or by covalent dimerization mediated by intermolecular disulfide bond formation. These distinct mechanisms of receptor activation converged upon tyrosine phosphorylation of cellular proteins, impacting cell motility. Survival of Ba/F3 cells transformed to IL-3 independence by the ERBB2 extracellular domain mutants was abrogated by treatment with small-molecule inhibitors of ERBB2, raising the possibility that patients harboring such mutations could benefit from ERBB2-directed therapy.HER2 | breast cancer | bladder cancer L ung cancer is the leading cause of cancer death, accounting for over 150,000 deaths annually in the United States alone (1). Current treatment options are thus inadequate for the majority of patients and additional therapies are needed. Mutationally activated oncogenes that promote tumorigenesis represent potential drug targets due to frequent dependency of tumor cells on such oncogenes (2, 3), and somatically altered receptor tyrosine kinases in particular have been successfully exploited as therapeutic targets in several cancers.The prototypical therapy targeted to a somatically activated tyrosine kinase oncogene is imatinib mesylate, which targets the BCR-ABL fusion protein in chronic myelogenous leukemia (4). Targeted therapies developed for lung cancer include gefitinib and erlotinib, small-molecule inhibitors of mutationally activated EGFR in lung adenocarcinoma (5-8), and crizotinib, a smallmolecule inhibitor of the EML4-ALK translocation product in lung adenocarcinoma (9). Trastuzumab, a monoclonal antibody inhibitor targeting ERBB2, and the small-molecule EGFR/ ERBB2 inhibitor lapatinib are effective in ERBB2-amplified patients with breast cancer (10, 11).The advent of next-generation sequencing technologies has enabled compilation of large somatic mutation datasets from cancer sequencing studies. Statistical methods that examine differences in gene mutation frequency can reveal evidence of positive selection; however, demonstration of the contribution of a mutated gene to tumorigenesis additionally requires functional validation. To identify new lung cancer oncogenes, we systematically assessed somatic alleles of significantly mutated receptor tyrosine kinase genes reported in patients with lung adenocarcinoma (12) for activity in cellular transformation assays.Although most receptor tyrosine kinase mutations tested failed to score, novel extracellular domain mutations of ERBB2 were oncogenic. Our results indicate a unique therapeutic opportunity for patients with lung and breast cancer who harbor extracellular domain mutations of ERBB2. Resul...
Targeted cancer therapies often induce "outlier" responses in molecularly defined patient subsets. One patient with advanced-stage lung adenocarcinoma, who was treated with oral sorafenib, demonstrated a near-complete clinical and radiographic remission for 5 years. Whole-genome sequencing and RNA sequencing of primary tumor and normal samples from this patient identified a somatic mutation, ARAF S214C, present in the cancer genome and expressed at high levels. Additional mutations affecting this residue of ARAF and a nearby residue in the related kinase RAF1 were demonstrated across 1% of an independent cohort of lung adenocarcinoma cases. The ARAF mutations were shown to transform immortalized human airway epithelial cells in a sorafenib-sensitive manner. These results suggest that mutant ARAF is an oncogenic driver in lung adenocarcinoma and an indicator of sorafenib response.
DNMDP and related compounds, or velcrins, induce complex formation between the phosphodiesterase PDE3A and the SLFN12 protein, leading to a cytotoxic response in cancer cells that express elevated levels of both proteins. The mechanisms by which velcrins induce complex formation, and how the PDE3A-SLFN12 complex causes cancer cell death, are not fully understood. Here, we show that PDE3A and SLFN12 form a heterotetramer stabilized by binding of DNMDP. Interactions between the C-terminal alpha helix of SLFN12 and residues near the active site of PDE3A are required for complex formation, and are further stabilized by interactions between SLFN12 and DNMDP. Moreover, we demonstrate that SLFN12 is an RNase, that PDE3A binding increases SLFN12 RNase activity, and that SLFN12 RNase activity is required for DNMDP response. This new mechanistic understanding will facilitate development of velcrin compounds into new cancer therapies.
Cytotoxic molecules can kill cancer cells by disrupting critical cellular processes or by inducing novel activities. 6-(4-(Diethylamino)-3-nitrophenyl)-5-methyl-4,5-dihydropyridazin-3(2H)-one (DNMDP) is a small molecule that kills cancer cells by generation of novel activity. DNMDP induces complex formation between phosphodiesterase 3A (PDE3A) and schlafen family member 12 (SLFN12) and specifically kills cancer cells expressing elevated levels of these two proteins. Here, we examined the characteristics and covariates of the cancer cell response to DNMDP. On average, the sensitivity of human cancer cell lines to DNMDP is correlated with PDE3A expression levels. However, DNMDP could also bind the related protein, PDE3B, and PDE3B supported DNMDP sensitivity in the absence of PDE3A expression. Although inhibition of PDE3A catalytic activity did not account for DNMDP sensitivity, we found that expression of the catalytic domain of PDE3A in cancer cells lacking PDE3A is sufficient to confer sensitivity to DNMDP, and substitutions in the PDE3A active site abolish compound binding. Moreover, a genome-wide CRISPR screen identified the aryl hydrocarbon receptor–interacting protein (AIP), a co-chaperone protein, as required for response to DNMDP. We determined that AIP is also required for PDE3A-SLFN12 complex formation. Our results provide mechanistic insights into how DNMDP induces PDE3A-SLFN12 complex formation, thereby killing cancer cells with high levels of PDE3A and SLFN12 expression.
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