T cells develop in the thymus and are critical for adaptive immunity. Natural killer (NK) lymphocytes constitute an essential component of the innate immune system in tumor surveillance, reproduction and defense against microbes and viruses. Here we show that the transcription factor Bcl11b was expressed in all T cell compartments and was indispensable for T lineage development. When Bcl11b was deleted, T cells from all developmental stages acquired NK cell properties and concomitantly lost or decreased T cell–associated gene expression. These induced T-to–natural killer (ITNK) cells, which were morphologically and genetically similar to conventional NK cells, killed tumor cells in vitro and effectively prevented tumor metastasis in vivo. Therefore, ITNKs may represent a new cell source for cell-based therapies.

Triple-negative breast cancer (TNBC) has poor prognostic outcome compared with other types of breast cancer. The molecular and cellular mechanisms underlying TNBC pathology are not fully understood. Here, we report that the transcription factor BCL11A is overexpressed in TNBC including basal-like breast cancer (BLBC) and that its genomic locus is amplified in up to 38% of BLBC tumours. Exogenous BCL11A overexpression promotes tumour formation, whereas its knockdown in TNBC cell lines suppresses their tumourigenic potential in xenograft models. In the DMBA-induced tumour model, Bcl11a deletion substantially decreases tumour formation, even in p53-null cells and inactivation of Bcl11a in established tumours causes their regression. At the cellular level, Bcl11a deletion causes a reduction in the number of mammary epithelial stem and progenitor cells. Thus, BCL11A has an important role in TNBC and normal mammary epithelial cells. This study highlights the importance of further investigation of BCL11A in TNBC-targeted therapies.

Yu et al. demonstrate that the transcription factor Bcl11b is specifically expressed in mouse innate lymphoid progenitors committed to the ILC2 lineage and is required for their development. Bcl11b-deficient mice exhibit a complete lack of ILC2 development, which is confirmed by immune challenges with either papain treatment or influenza virus infection.

Functional analysis of mammalian genes in vivo is primarily achieved through analysing knockout mice. Now that the sequencing of several mammalian genomes has been completed, understanding functions of all the genes represents the next major challenge in the post-genome era. Generation of knockout mutant mice has currently been achieved by many research groups but only by making individual knockouts, one by one. New technological advances and the refinements of existing technologies are critical for genome-wide targeted mutagenesis in the mouse. We describe here new recombineering reagents and protocols that enable recombineering to be carried out in a 96-well format. Consequently, we are able to construct 96 conditional knockout targeting vectors simultaneously. Our new recombineering system makes it a reality to generate large numbers of precisely engineered DNA constructs for functional genomics studies.

Triple-negative breast cancer (TNBC) has the worst prognosis of any breast cancer subtype. To better understand the genetic forces driving TNBC, we performed a transposon mutagenesis screen in a phosphatase and tensin homolog (Pten) mutant mice and identified 12 candidate trunk drivers and a much larger number of progression genes. Validation studies identified eight TNBC tumor suppressor genes, including the GATA-like transcriptional repressor TRPS1. Down-regulation of TRPS1 in TNBC cells promoted epithelial-to-mesenchymal transition (EMT) by deregulating multiple EMT pathway genes, in addition to increasing the expression of SERPINE1 and SERPINB2 and the subsequent migration, invasion, and metastasis of tumor cells. Transposon mutagenesis has thus provided a better understanding of the genetic forces driving TNBC and discovered genes with potential clinical importance in TNBC.Sleeping Beauty | breast cancer | TRPS1 | metastasis | tumor suppressors B reast cancer is the second leading cause of cancer-related deaths in the United States. The Cancer Genome Atlas (TCGA) network has classified breast cancer into four main subtypes: luminal A, luminal B, HER2+, and basal-like (1-5). Basal-like or triplenegative breast cancer (TNBC) constitutes 10-20% of all breast cancers and has a higher rate of distal recurrence and a poorer prognosis than other breast cancer subtypes. Less than 30% of women with metastatic TNBC survive 5 y and almost all die from their disease despite adjuvant chemotherapy (1, 3-5). Mutations, rearrangements, or deletions in highly penetrant genes such as BRCA1, BRCA2, TP53, CDH1, STK11, and PTEN are important drivers of TNBC (6-8). PTEN is a dual-specificity phosphatase that antagonizes the PI3K/AKT pathway through its lipid phosphatase activity and negatively regulates the MAPK pathway through its protein phosphatase activity (9, 10). Mutations in PTEN drive epithelial-mesenchymal transition (EMT) and promote metastasis in TNBC (11-13). Similarly, in mice, heterozygous deletion of Pten induces mammary tumors with basal-like characteristics (14)(15)(16)(17).Despite all of the cancer genome-sequencing efforts, there is still an incomplete understanding of the genes and genetic networks driving TNBC. New technologies that would provide a more complete understanding of the genetics of TNBC are still needed to deconvolute the complexity of this deadly cancer. Our laboratory and others have pioneered the use of transposon mutagenesis in mice as a tool for cancer gene discovery (18-26). Transposons induce cancer by randomly inserting into the mouse genome, mutating, and disrupting potential cancer genes. Transposon insertions in tumors thus serve as molecular tags for the high-throughput cloning and identification of cancer genes. In addition, because transposon insertions are PCR-amplified before they are sequenced, insertional mutations in cancer genes that are present in only a small fraction of tumor cells can be identified. Transposon mutagenesis can thus identify genes that are functioning at th...

30The systematic identification of genetic events driving cellular transformation and tumor progression in the absence 31 of a highly recurrent oncogenic driver mutation is a challenge in cutaneous oncology. In cutaneous squamous cell 32 carcinoma (cuSCC), the high UV-induced mutational burden poses a hurdle to achieve a complete molecular 33 landscape of this disease. Here, we utilized the Sleeping Beauty transposon mutagenesis system to statistically 34 define drivers of keratinocyte transformation and cuSCC progression in vivo in the absence of UV-IR, and identified 35 established tumor suppressor genes, as well as previously unknown oncogenic drivers of cuSCC. Functional analysis 36 confirms an oncogenic role for the ZMIZ genes, and tumor suppressive roles for KMT2C, CREBBP and NCOA2, in the 37 initiation or progression of human cuSCC. Taken together, our in vivo screen demonstrates an extremely 38 heterogeneous genetic landscape of cuSCC initiation and progression, which could be harnessed to better 39 understand skin oncogenic etiology and prioritize therapeutic candidates. 40

Cre-loxP recombination is widely used for genetic manipulation of the mouse genome. Here, we report generation and characterization of a new Cre line, Stella-Cre, where Cre expression cassette was targeted to the 3′ UTR of the Stella locus. Stella is specifically expressed in preimplantation embryos and in the germline. Cre-loxP recombination efficiency in Stella-Cre mice was investigated at several genomic loci including Rosa26, Jak2, and Npm1. At all the loci examined, we observed 100% Cre-loxP recombination efficiency in the embryos and in the germline. Thus, Stella-Cre mice serve as a very efficient deleter line. genesis 49:689–695, 2011. © 2011 Wiley-Liss, Inc.

The systematic identification of genetic events driving cellular transformation and tumor progression in the absence of a highly recurrent oncogenic driver mutation is a challenge in cutaneous oncology. In cutaneous squamous cell carcinoma (cuSCC), the high UV-induced mutational burden poses a hurdle to achieve a complete molecular landscape of this disease. Here, we utilized the Sleeping Beauty transposon mutagenesis system to statistically define drivers of keratinocyte transformation and cuSCC progression in vivo in the absence of UV-IR, and identified both known tumor suppressor genes and novel oncogenic drivers of cuSCC. Functional analysis confirms an oncogenic role for the ZMIZ genes, and tumor suppressive roles for KMT2C, CREBBP and NCOA2, in the initiation or progression of human cuSCC. Taken together, our in vivo screen demonstrates an extremely heterogeneous genetic landscape of cuSCC initiation and progression, which can be harnessed to better understand skin oncogenic etiology and prioritize therapeutic candidates.