Fluorophore-NanoLuc BRET Reporters Enable Sensitive In Vivo Optical Imaging and Flow Cytometry for Monitoring Tumorigenesis

Fluorescent proteins are widely used to study molecular and cellular events, yet this traditionally relies on delivery of excitation light, which can trigger autofluorescence, photoxicity, and photobleaching, impairing their use in vivo. Accordingly, chemiluminescent light sources such as those generated by luciferases have emerged, as they do not require excitation light. However, current luciferase reporters lack the brightness needed to visualize events in deep tissues. We report the creation of chimeric eGFP-NanoLuc (GpNLuc) and LSSmOrange-NanoLuc (OgNLuc) fusion reporter proteins coined LumiFluors, which combine the benefits of eGFP or LSSmOrange fluorescent proteins with the bright, glow-type bioluminescent light generated by an enhanced small luciferase subunit (NanoLuc) of the deep sea shrimp Oplophorus gracilirostris. The intramolecular bioluminescence resonance energy transfer (BRET) that occurs between NanoLuc and the fused fluorophore generates the brightest bioluminescent signal known to date, including improved intensity, sensitivity and durable spectral properties, thereby dramatically reducing image acquisition times and permitting highly sensitive in vivo imaging. Notably, the self-illuminating and bi-functional nature of these LumiFluor reporters enables greatly improved spatio-temporal monitoring of very small numbers of tumor cells via in vivo optical imaging and also allows the isolation and analyses of single cells by flow cytometry. Thus, LumiFluor reporters are inexpensive, robust, non-invasive tools that allow for markedly improved in vivo optical imaging of tumorigenic processes

Pan-cancer Alterations of the MYC Oncogene and Its Proximal Network across the Cancer Genome Atlas

Although theMYConcogene has been implicated incancer, a systematic assessment of alterations ofMYC, related transcription factors, and co-regulatoryproteins, forming the proximal MYC network (PMN),across human cancers is lacking. Using computa-tional approaches, we define genomic and proteo-mic features associated with MYC and the PMNacross the 33 cancers of The Cancer Genome Atlas.Pan-cancer, 28% of all samples had at least one ofthe MYC paralogs amplified. In contrast, the MYCantagonists MGA and MNT were the most frequentlymutated or deleted members, proposing a roleas tumor suppressors.MYCalterations were mutu-ally exclusive withPIK3CA,PTEN,APC,orBRAFalterations, suggesting that MYC is a distinct onco-genic driver. Expression analysis revealed MYC-associated pathways in tumor subtypes, such asimmune response and growth factor signaling; chro-matin, translation, and DNA replication/repair wereconserved pan-cancer. This analysis reveals insightsinto MYC biology and is a reference for biomarkersand therapeutics for cancers with alterations ofMYC or the PMN

Tipping the MYC–MIZ1 balance: targeting the HUWE1 ubiquitin ligase selectively blocks MYC‐activated genes

MYC family oncoproteins (MYC, N‐MYC and L‐MYC) function as basic helix‐loop‐helix‐leucine zipper (bHLH‐Zip) transcription factors that are activated (i.e., overexpressed) in well over half of all human malignancies (Boxer & Dang, ; Beroukhim et al, ). In this issue of EMBO Molecular Medicine, Eilers and colleagues (Peter et al, ) describe a novel approach to disable MYC, whereby inhibition of the ubiquitin ligase HUWE1 stabilizes MIZ1 and leads to the selective repression of MYC‐activated target genes

Clonal analysis of TET2 and JAK2 mutations suggests that TET2 can be a late event in the progression of myeloproliferative neoplasms

Somatic mutations in TET2 occur in patients with myeloproliferative neoplasms and other hematologic malignancies. It has been suggested that TET2 is a tumor suppressor gene and mutations in TET2 precede the acquisition of JAK2-V617F. To examine the order of events, we performed colony assays and genotyped TET2 and JAK2 in individual colonies. In 4 of 8 myeloproliferative neoplasm patients, we found that some colonies with mutated TET2 carried wild-type JAK2, whereas others were JAK2-V617F positive, indicating that TET2 occurred before JAK2-V617F. One of these patients carried a germline TET2 mutation. However, in 2 other patients, we obtained data compatible with the opposite order of events, with JAK2 exon 12 mutation preceding TET2 mutation in one case. Finally, in 2 of 8 patients, the TET2 and JAK2-V617F mutations defined 2 separate clones. The lack of a strict temporal order of occurrence makes it unlikely that mutations in TET2 represent a predisposing event for acquiring mutations in JAK2

Clonal analysis of deletions on chromosome 20q and JAK2-V617F in MPD suggests that del20q acts independently and is not one of the predisposing mutations for JAK2-V617F

We developed a real-time copy number polymerase chain reaction assay for deletions on chromosome 20q (del20q), screened peripheral blood granulocytes from 664 patients with myeloproliferative disorders, and identified 19 patients with del20q (2.9%), of which 14 (74%) were also positive for JAK2-V617F. To examine the temporal relationship between the occurrence of del20q and JAK2-V617F, we performed colony assays in methylcellulose, picked individual burst-forming units-erythroid (BFU-E) and colony-forming units-granulocyte (CFU-G) colonies, and genotyped each colony individually for del20q and JAK2-V617F. In 2 of 9 patients, we found that some colonies with del20q carried only wild-type JAK2, whereas other del20q colonies were JAK2-V617F positive, indicating that del20q occurred before the acquisition of JAK2-V617F. However, in colonies from 3 of 9 patients, we observed the opposite order of events. The lack of a strict temporal order of occurrence makes it doubtful that del20q represents a predisposing event for JAK2-V617F. In 2 patients with JAK2-V617F and 1 patient with MPL-W515L, microsatellite analysis revealed that del20q affected chromosomes of different parental origin and/or 9pLOH occurred at least twice. The fact that rare somatic events, such as del20q or 9pLOH, occurred more than once in subclones from the same patients suggests that the myeloproliferative disorder clone carries a predisposition to acquiring such genetic alterations

Clonal analysis of TET2 and JAK2 mutations suggests that TET2 can be a late event in the progression of myeloproliferative neoplasms

Somatic mutations in TET2 occur in patients with myeloproliferative neoplasms and other hematologic malignancies. It has been suggested that TET2 is a tumor suppressor gene and mutations in TET2 precede the acquisition of JAK2-V617F. To examine the order of events, we performed colony assays and genotyped TET2 and JAK2 in individual colonies. In 4 of 8 myeloproliferative neoplasm patients, we found that some colonies with mutated TET2 carried wild-type JAK2, whereas others were JAK2-V617F positive, indicating that TET2 occurred before JAK2-V617F. One of these patients carried a germline TET2 mutation. However, in 2 other patients, we obtained data compatible with the opposite order of events, with JAK2 exon 12 mutation preceding TET2 mutation in one case. Finally, in 2 of 8 patients, the TET2 and JAK2-V617F mutations defined 2 separate clones. The lack of a strict temporal order of occurrence makes it unlikely that mutations in TET2 represent a predisposing event for acquiring mutations in JAK2