Explore the vast range of titles available.

Key Points Recent cancer genome deep sequencing efforts have revealed an unanticipated high frequency of mutations in G proteins and G-protein-coupled receptors (GPCRs) in most tumour types. A striking 4.2% of all tumour sequences deposited to date show activating mutations in GNAS (a complex locus that encodes Gα s ). Transforming mutations in GNAS have been well documented in human thyroid and pituitary tumours, and recent sequencing efforts have shown these mutations to be present in a wide variety of additional tumour types, including colon cancer, hepatocellular carcinoma, and parathyroid, ovarian, endometrial, biliary tract and pancreatic tumours. Mutually exclusive activating mutations in GNAQ or GNA11 (encoding Gα q family members) occur in 5.6% of tumours, and they are present in ∼66% and ∼6% of melanomas arising in the eye and skin, respectively, where they can act as driver oncogenes. Hotspot mutations in Gα s (R201 and Q227) as well as Gα q and Gα 11 (R183 and Q209) disrupt the GTPase activity, thereby leading to constitutive activity and persistent signalling. Nearly 20% of human cancers harbour mutations in GPCRs. The most frequently mutated GPCRs include thyroid-stimulating hormone receptor (TSHR), Smoothened (SMO), glutamate metabotropic receptors (GRMs), members of the adhesion family of GPCRs and receptors for bioactive lipid mediators such as lysophosphatidic acid (LPA) and sphingosine-1-phosphate (S1P) that accumulate in the tumour microenvironment. Many GPCR mutations are still uncharacterized with respect to their potential contribution to tumorigenesis and cancer progression. Aberrant expression, overexpression or signal reprogramming of GPCRs and G proteins in tumour cells can contribute to cancer development and progression. These alterations may arise from cancer-specific changes in gene copy number, as well as from other genetic, epigenetic and post-translational changes resulting in higher protein expression, thereby enhancing tumour progression and metastasis. Detailed three dimensional structures of GPCRs in various activation states can now help to explain the functional impact of cancer-associated GPCR mutations, and guide the rational design of signalling-selective GPCR agonists, antagonists and allosteric modulators. G proteins, GPCRs and their linked signalling circuitry represent novel therapeutic targets for cancer prevention and treatment. Aberrant expression and activity of G proteins and G-protein-coupled receptors (GPCRs) are frequently associated with tumorigenesis. Recent deep sequencing studies have shown that nearly 20% of human tumours harbour mutations in GPCRs. This Analysis article reviews these findings and the indications that G proteins, GPCRs and their signalling pathways represent novel therapeutic targets for cancer prevention and treatment. Aberrant expression and activity of G proteins and G-protein-coupled receptors (GPCRs) are frequently associated with tumorigenesis. Deep sequencing studies show that 4.2% of tumours carry activating mutations in GNAS (encoding Gα s ), and that oncogenic activating mutations in genes encoding Gα q family members ( GNAQ or GNA11 ) are present in ∼66% and ∼6% of melanomas arising in the eye and skin, respectively. Furthermore, nearly 20% of human tumours harbour mutations in GPCRs. Many human cancer-associated viruses also express constitutively active viral GPCRs. These studies indicate that G proteins, GPCRs and their linked signalling circuitry represent novel therapeutic targets for cancer prevention and treatment.

Raphael Bueno, Eric Stawiski, Somasekar Seshagiri and colleagues present a comprehensive genomic analysis of malignant pleural mesothelioma. They identify four distinct molecular subtypes using RNA-seq data and highlight recurrent somatic mutations, gene fusions and splicing alterations. We analyzed transcriptomes ( n = 211), whole exomes ( n = 99) and targeted exomes ( n = 103) from 216 malignant pleural mesothelioma (MPM) tumors. Using RNA-seq data, we identified four distinct molecular subtypes: sarcomatoid, epithelioid, biphasic-epithelioid (biphasic-E) and biphasic-sarcomatoid (biphasic-S). Through exome analysis, we found BAP1 , NF2 , TP53 , SETD2 , DDX3X , ULK2 , RYR2 , CFAP45 , SETDB1 and DDX51 to be significantly mutated ( q -score ≥ 0.8) in MPMs. We identified recurrent mutations in several genes, including SF3B1 (∼2%; 4/216) and TRAF7 (∼2%; 5/216). SF3B1-mutant samples showed a splicing profile distinct from that of wild-type tumors. TRAF7 alterations occurred primarily in the WD40 domain and were, except in one case, mutually exclusive with NF2 alterations. We found recurrent gene fusions and splice alterations to be frequent mechanisms for inactivation of NF2 , BAP1 and SETD2 . Through integrated analyses, we identified alterations in Hippo, mTOR, histone methylation, RNA helicase and p53 signaling pathways in MPMs.

Snakebite envenoming is a serious and neglected tropical disease that kills ~100,000 people annually. High-quality, genome-enabled comprehensive characterization of toxin genes will facilitate development of effective humanized recombinant antivenom. We report a de novo near-chromosomal genome assembly of Naja naja , the Indian cobra, a highly venomous, medically important snake. Our assembly has a scaffold N50 of 223.35 Mb, with 19 scaffolds containing 95% of the genome. Of the 23,248 predicted protein-coding genes, 12,346 venom-gland-expressed genes constitute the ‘venom-ome’ and this included 139 genes from 33 toxin families. Among the 139 toxin genes were 19 ‘venom-ome-specific toxins’ (VSTs) that showed venom-gland-specific expression, and these probably encode the minimal core venom effector proteins. Synthetic venom reconstituted through recombinant VST expression will aid in the rapid development of safe and effective synthetic antivenom. Additionally, our genome could serve as a reference for snake genomes, support evolutionary studies and enable venom-driven drug discovery. Analysis of a near-chromosomal genome assembly and transcriptome profiling of the Indian cobra identifies genes expressed in the venom glands. These data should help develop a new antivenom.

Somasekar Seshagiri, James Brugarolas and colleagues report the mutational landscape of 167 non–clear cell renal cell carcinomas (nccRCCs) from multiple subtypes. They identify subtype-specific driver mutations and gene fusions, including ones involving MITF , which result in expression of the anti-apoptotic protein BIRC7 and might thus indicate candidates for treatment with BIRC7 inhibitors. To further understand the molecular distinctions between kidney cancer subtypes, we analyzed exome, transcriptome and copy number alteration data from 167 primary human tumors that included renal oncocytomas and non–clear cell renal cell carcinomas (nccRCCs), consisting of papillary (pRCC), chromophobe (chRCC) and translocation (tRCC) subtypes. We identified ten significantly mutated genes in pRCC, including MET , NF2 , SLC5A3 , PNKD and CPQ . MET mutations occurred in 15% (10/65) of pRCC samples and included previously unreported recurrent activating mutations. In chRCC, we found TP53 , PTEN , FAAH2 , PDHB , PDXDC1 and ZNF765 to be significantly mutated. Gene expression analysis identified a five-gene set that enabled the molecular classification of chRCC, renal oncocytoma and pRCC. Using RNA sequencing, we identified previously unreported gene fusions, including ACTG1 - MITF fusion. Ectopic expression of the ACTG1 - MITF fusion led to cellular transformation and induced the expression of downstream target genes. Finally, we observed upregulation of the anti-apoptotic factor BIRC7 in MiTF-high RCC tumors, suggesting a potential therapeutic role for BIRC7 inhibitors.

Sekar Seshagiri and colleagues report exome, transcriptome and copy-number alteration data in small-cell lung cancer. The authors find SOX2 amplification in 27% of samples and also identify a recurrent RFL - MYCL1 fusion. Small-cell lung cancer (SCLC) is an exceptionally aggressive disease with poor prognosis. Here, we obtained exome, transcriptome and copy-number alteration data from approximately 53 samples consisting of 36 primary human SCLC and normal tissue pairs and 17 matched SCLC and lymphoblastoid cell lines. We also obtained data for 4 primary tumors and 23 SCLC cell lines. We identified 22 significantly mutated genes in SCLC, including genes encoding kinases, G protein–coupled receptors and chromatin-modifying proteins. We found that several members of the SOX family of genes were mutated in SCLC. We also found SOX2 amplification in ∼27% of the samples. Suppression of SOX2 using shRNAs blocked proliferation of SOX2 -amplified SCLC lines. RNA sequencing identified multiple fusion transcripts and a recurrent RLF - MYCL1 fusion. Silencing of MYCL1 in SCLC cell lines that had the RLF-MYCL1 fusion decreased cell proliferation. These data provide an in-depth view of the spectrum of genomic alterations in SCLC and identify several potential targets for therapeutic intervention.

Advances in single-cell RNA sequencing (scRNA-Seq) have allowed for comprehensive analyses of single cell data. However, current analyses of scRNA-Seq data usually start from unsupervised clustering or visualization. These methods ignore prior knowledge of transcriptomes and the probable structures of the data. Moreover, cell identification heavily relies on subjective and possibly inaccurate human inspection afterwards. To address these analytical challenges, we developed SCINA (Semi-supervised Category Identification and Assignment), a semi-supervised model that exploits previously established gene signatures using an expectation–maximization (EM) algorithm. SCINA is applicable to scRNA-Seq and flow cytometry/CyTOF data, as well as other data of similar format. We applied SCINA to a wide range of datasets, and showed its accuracy, stability and efficiency, which exceeded most popular unsupervised approaches. SCINA discovered an intermediate stage of oligodendrocytes from mouse brain scRNA-Seq data. SCINA also detected immune cell population changes in cytometry data in a genetically-engineered mouse model. Furthermore, SCINA performed well with bulk gene expression data. Specifically, we identified a new kidney tumor clade with similarity to FH-deficient tumors (FHD), which we refer to as FHD-like tumors (FHDL). Overall, SCINA provides both methodological advances and biological insights from perspectives different from traditional analytical methods.

COVID-19 is a respiratory illness caused by a novel coronavirus called SARS-CoV-2. The viral spike (S) protein engages the human angiotensin-converting enzyme 2 (ACE2) receptor to invade host cells with ~10–15-fold higher affinity compared to SARS-CoV S-protein, making it highly infectious. Here, we assessed if ACE2 polymorphisms can alter host susceptibility to SARS-CoV-2 by affecting this interaction. We analyzed over 290,000 samples representing >400 population groups from public genomic datasets and identified multiple ACE2 protein-altering variants. Using reported structural data, we identified natural ACE2 variants that could potentially affect virus–host interaction and thereby alter host susceptibility. These include variants S19P, I21V, E23K, K26R, T27A, N64K, T92I, Q102P and H378R that were predicted to increase susceptibility, while variants K31R, N33I, H34R, E35K, E37K, D38V, Y50F, N51S, M62V, K68E, F72V, Y83H, G326E, G352V, D355N, Q388L and D509Y were predicted to be protective variants that show decreased binding to S-protein. Using biochemical assays, we confirmed that K31R and E37K had decreased affinity, and K26R and T92I variants showed increased affinity for S-protein when compared to wildtype ACE2. Consistent with this, soluble ACE2 K26R and T92I were more effective in blocking entry of S-protein pseudotyped virus suggesting that ACE2 variants can modulate susceptibility to SARS-CoV-2.Suryamohan, Diwanji, Stawiski et al. identify natural ACE2 variants that are predicted to alter virus–host interactions. They find that soluble ACE2 K26R and T92I variants are more effective in blocking the entry of SARS-CoV-2 S-protein pseudotyped virus, compared to wild-type ACE2. This study suggests that ACE2 variants may modulate the host susceptibility to SARS-CoV-2.

The AKT kinases have emerged as promising therapeutic targets in oncology and both allosteric and ATP-competitive AKT inhibitors have entered clinical investigation. However, long-term efficacy of such inhibitors will likely be challenged by the development of resistance. We have established prostate cancer models of acquired resistance to the allosteric inhibitor MK-2206 or the ATP-competitive inhibitor ipatasertib following prolonged exposure. While alterations in AKT are associated with acquired resistance to MK-2206, ipatasertib resistance is driven by rewired compensatory activity of parallel signaling pathways. Importantly, MK-2206 resistance can be overcome by treatment with ipatasertib, while ipatasertib resistance can be reversed by co-treatment with inhibitors of pathways including PIM signaling. These findings demonstrate that distinct resistance mechanisms arise to the two classes of AKT inhibitors and that combination approaches may reverse resistance to ATP-competitive inhibition. How resistance to different classes of AKT inhibitors can emerge is unclear. Here, the authors show that resistance to allosteric inhibitors is mainly due to mutation of AKT1 while the ATP competitive resistance is driven by activation of PIM kinases in prostate cancer models.

Background Maturity-onset diabetes of the young (MODY) is an early-onset, autosomal dominant form of non-insulin dependent diabetes. Genetic diagnosis of MODY can transform patient management. Earlier data on the genetic predisposition to MODY have come primarily from familial studies in populations of European origin. Methods In this study, we carried out a comprehensive genomic analysis of 289 individuals from India that included 152 clinically diagnosed MODY cases to identify variants in known MODY genes. Further, we have analyzed exome data to identify putative MODY relevant variants in genes previously not implicated in MODY. Functional validation of MODY relevant variants was also performed. Results We found MODY 3 ( HNF1A ; 7.2%) to be most frequently mutated followed by MODY 12 ( ABCC8 ; 3.3%). They together account for ~ 11% of the cases. In addition to known MODY genes, we report the identification of variants in RFX6 , WFS1 , AKT2 , NKX6–1 that may contribute to development of MODY. Functional assessment of the NKX6–1 variants showed that they are functionally impaired. Conclusions Our findings showed HNF1A and ABCC8 to be the most frequently mutated MODY genes in south India. Further we provide evidence for additional MODY relevant genes, such as NKX6–1 , and these require further validation.

Gastric cancer is the second leading cause of worldwide cancer mortality, yet the underlying genomic alterations remain poorly understood. Here we perform exome and transcriptome sequencing and SNP array assays to characterize 51 primary gastric tumours and 32 cell lines. Meta-analysis of exome data and previously published data sets reveals 24 significantly mutated genes in microsatellite stable (MSS) tumours and 16 in microsatellite instable (MSI) tumours. Over half the patients in our collection could potentially benefit from targeted therapies. We identify 55 splice site mutations accompanied by aberrant splicing products, in addition to mutation-independent differential isoform usage in tumours. ZAK kinase isoform TV1 is preferentially upregulated in gastric tumours and cell lines relative to normal samples. This pattern is also observed in colorectal, bladder and breast cancers. Overexpression of this particular isoform activates multiple cancer-related transcription factor reporters, while depletion of ZAK in gastric cell lines inhibits proliferation. These results reveal the spectrum of genomic and transcriptomic alterations in gastric cancer, and identify isoform-specific oncogenic properties of ZAK. The genetic basis of gastric cancer, the fourth most common cancer worldwide, remains poorly understood. Here, the authors sequence and analyse the exomes and transcriptomes of primary gastric tumours and cell lines, and identify a ZAK kinase isoform that may have an oncogenic role in gastric cancer.