Author
Linda Chee
Bio: Linda Chee is an academic researcher from University of Nebraska Medical Center. The author has contributed to research in topics: Cancer & Homologous recombination. The author has an hindex of 3, co-authored 5 publications receiving 87 citations.
Topics: Cancer, Homologous recombination, Gene, FOXM1, DNA repair
Papers
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TL;DR: FOXM1 expression was significantly elevated in tumors with FOXM1 amplification, p53 inactivation, and Rb-E2F deregulation, and was remarkably high in testicular germ cell tumors (TGCT), high-grade serous ovarian cancer (HGSC), and basal breast cancer (BBC).
Abstract: FOXM1 is frequently overexpressed in cancer, but this has not been studied in a comprehensive manner. We utilized genotype-tissue expression (GTEx) normal and The Cancer Genome Atlas (TCGA) tumor data to define FOXM1 expression, including its isoforms, and to determine the genetic alterations that promote FOXM1 expression in cancer. Additionally, we used human fallopian tube epithelial (FTE) cells to dissect the role of Retinoblastoma (Rb)-E2F and Cyclin E1 in FOXM1 regulation, and a novel human embryonic kidney cell (HEK293T) CRISPR FOXM1 knockout model to define isoform-specific transcriptional programs. FOXM1 expression, at the mRNA and protein level, was significantly elevated in tumors with FOXM1 amplification, p53 inactivation, and Rb-E2F deregulation. FOXM1 expression was remarkably high in testicular germ cell tumors (TGCT), high-grade serous ovarian cancer (HGSC), and basal breast cancer (BBC). FOXM1 expression in cancer was associated with genomic instability, as measured using aneuploidy signatures. FTE models confirmed a role for Rb-E2F signaling in FOXM1 regulation and in particular identified Cyclin E1 as a novel inducer of FOXM1 expression. Among the three FOXM1 isoforms, FOXM1c showed the highest expression in normal and tumor tissues and cancer cell lines. The CRISPR knockout model demonstrated that FOXM1b and FOXM1c are transcriptionally active, while FOXM1a is not. Finally, we were unable to confirm the existence of a FOXM1 auto-regulatory loop. This study provides significant and novel information regarding the frequency, causes, and consequences of elevated FOXM1 expression in human cancer.
121 citations
TL;DR: Based on their restricted expression in normal tissues and increased expression and association with poor prognosis in ovarian cancer, POTEs are potential oncogenes and therapeutic targets in this malignancy.
Abstract: The POTE family includes 14 genes in three phylogenetic groups. We determined POTE mRNA expression in normal tissues, epithelial ovarian and high-grade serous ovarian cancer (EOC, HGSC), and pan-cancer, and determined the relationship of POTE expression to ovarian cancer clinicopathology. Groups 1 & 2 POTEs showed testis-specific expression in normal tissues, consistent with assignment as cancer-testis antigens (CTAs), while Group 3 POTEs were expressed in several normal tissues, indicating they are not CTAs. Pan-POTE and individual POTEs showed significantly elevated expression in EOC and HGSC compared to normal controls. Pan-POTE correlated with increased stage, grade, and the HGSC subtype. Select individual POTEs showed increased expression in recurrent HGSC, and POTEE specifically associated with reduced HGSC OS. Consistent with tumors, EOC cell lines had significantly elevated Pan-POTE compared to OSE and FTE cells. Notably, Group 1 & 2 POTEs (POTEs A/B/B2/C/D), Group 3 POTE-actin genes (POTEs E/F/I/J/KP), and other Group 3 POTEs (POTEs G/H/M) show within-group correlated expression, and pan-cancer analyses of tumors and cell lines confirmed this relationship. Based on their restricted expression in normal tissues and increased expression and association with poor prognosis in ovarian cancer, POTEs are potential oncogenes and therapeutic targets in this malignancy.
20 citations
TL;DR: This paper showed that RHNO1 and FOXM1 are head-to-head (i.e., bidirectional) genes (BDG) regulated by a BDP (named F/R-BDP), which is a potential therapeutic approach for ovarian and other cancers.
Abstract: The FOXM1 transcription factor is an oncoprotein and a top biomarker of poor prognosis in human cancer. Overexpression and activation of FOXM1 is frequent in high-grade serous carcinoma (HGSC), the most common and lethal form of human ovarian cancer, and is linked to copy number gains at chromosome 12p13.33. We show that FOXM1 is co-amplified and co-expressed with RHNO1, a gene involved in the ATR-Chk1 signaling pathway that functions in the DNA replication stress response. We demonstrate that FOXM1 and RHNO1 are head-to-head (i.e., bidirectional) genes (BDG) regulated by a bidirectional promoter (BDP) (named F/R-BDP). FOXM1 and RHNO1 each promote oncogenic phenotypes in HGSC cells, including clonogenic growth, DNA homologous recombination repair, and poly-ADP ribosylase inhibitor resistance. FOXM1 and RHNO1 are one of the first examples of oncogenic BDG, and therapeutic targeting of FOXM1/RHNO1 BDG is a potential therapeutic approach for ovarian and other cancers.
9 citations
TL;DR: There is functional cooperativity between FOXM1 and RHNO1 in cancer cells, and combinatorial targeting of this bidirectional gene pair may be a novel cancer therapeutic strategy, and the data provide evidence that biddirectional gene units function in human cancer.
Abstract: Summary We report that the oncogenic transcription factor FOXM1 is arranged in a head-to-head configuration with RHNO1, a gene involved in the ATR/CHK1-dependent DNA replication stress (DRS) response. FOXM1 and RHNO1 are both amplified and upregulated in high-grade serous ovarian cancer (HGSC). FOXM1 and RHNO1 expression are closely associated in normal and cancer tissues, including single cells, and a bidirectional promoter (F/R-BDP) mediates balanced expression. Targeting of FOXM1 and RHNO1 in HGSC cells using shRNA, CRISPR mutagenesis, or CRISPR interference directed to the F/R-BDP reduced DNA homologous recombination repair (HR) capacity, increased DNA damage, reduced clonogenic survival, and sensitized HGSC cells to the poly-ADP ribosylase inhibitor (PARPi) olaparib. Thus, there is functional cooperativity between FOXM1 and RHNO1 in cancer cells, and combinatorial targeting of this bidirectional gene pair may be a novel cancer therapeutic strategy. More broadly, our data provide evidence that bidirectional gene units function in human cancer.
3 citations
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01 Apr 2016
TL;DR: Tirosh et al. as discussed by the authors applied single-cell RNA sequencing (RNA-seq) to 4645 single cells isolated from 19 patients, profiling malignant, immune, stromal, and endothelial cells.
Abstract: Single-cell expression profiles of melanoma Tumors harbor multiple cell types that are thought to play a role in the development of resistance to drug treatments. Tirosh et al. used single-cell sequencing to investigate the distribution of these differing genetic profiles within melanomas. Many cells harbored heterogeneous genetic programs that reflected two different states of genetic expression, one of which was linked to resistance development. Following drug treatment, the resistance-linked expression state was found at a much higher level. Furthermore, the environment of the melanoma cells affected their gene expression programs. Science, this issue p. 189 Melanoma cells show transcriptional heterogeneity. To explore the distinct genotypic and phenotypic states of melanoma tumors, we applied single-cell RNA sequencing (RNA-seq) to 4645 single cells isolated from 19 patients, profiling malignant, immune, stromal, and endothelial cells. Malignant cells within the same tumor displayed transcriptional heterogeneity associated with the cell cycle, spatial context, and a drug-resistance program. In particular, all tumors harbored malignant cells from two distinct transcriptional cell states, such that tumors characterized by high levels of the MITF transcription factor also contained cells with low MITF and elevated levels of the AXL kinase. Single-cell analyses suggested distinct tumor microenvironmental patterns, including cell-to-cell interactions. Analysis of tumor-infiltrating T cells revealed exhaustion programs, their connection to T cell activation and clonal expansion, and their variability across patients. Overall, we begin to unravel the cellular ecosystem of tumors and how single-cell genomics offers insights with implications for both targeted and immune therapies.
823 citations
TL;DR: In this paper, the bone microenvironment facilitates breast and prostate cancer cells to further metastasize and establish multi-organ secondary metastases, and the metastasis-promoting effect is driven by epigenetic reprogramming.
89 citations
TL;DR: This work demonstrated that the bone microenvironment facilitates breast and prostate cancer cells to further metastasize and establish multi-organ secondary metastases, and suggested a stable reprogramming process that engenders cancer cells more metastatic.
Abstract: Metastasis has been considered as the terminal step of tumor progression. However, recent clinical studies suggest that many metastases are seeded from other metastases, rather than primary tumors. Thus, some metastases can further spread, but the corresponding pre-clinical models are lacking. By using several approaches including parabiosis and an evolving barcode system, we demonstrated that the bone microenvironment facilitates breast and prostate cancer cells to further metastasize and establish multi-organ secondary metastases. Importantly, dissemination from the bone microenvironment appears to be more aggressive compared to that from mammary tumors and lung metastases. We further uncovered that this metastasis-promoting effect is independent from genetic selection, as single cell-derived cancer cell populations (SCPs) exhibited enhanced metastasis capacity after being extracted from the bone microenvironment. Taken together, our work revealed a previously unappreciated effect of the bone microenvironment on metastasis evolution, and suggested a stable reprogramming process that engenders cancer cells more metastatic.
64 citations
TL;DR: The authors demonstrate the specific targeting of endogenous KRAS protein for degradation from cancer cells, and regression of tumours expressing mutant KRAS in a mouse model to show that specific KRAS degradation is an important therapeutic strategy to affect tumoursExpressing any of the range of KRAS mutations.
Abstract: Tumour-associated KRAS mutations are the most prevalent in the three RAS-family isoforms and involve many different amino-acids Therefore, molecules able to interfere with mutant KRAS protein are potentially important for wide-ranging tumour therapy We describe the engineering of two RAS degraders based on protein macromolecules (macrodrugs) fused to specific E3 ligases A KRAS-specific DARPin fused to the VHL E3 ligase is compared to a pan-RAS intracellular single domain antibody (iDAb) fused to the UBOX domain of the CHIP E3 ligase We demonstrate that while the KRAS-specific DARPin degrader induces specific proteolysis of both mutant and wild type KRAS, it only inhibits proliferation of cancer cells expressing mutant KRAS in vitro and in vivo Pan-RAS protein degradation, however, affects proliferation irrespective of the RAS mutation These data show that specific KRAS degradation is an important therapeutic strategy to affect tumours expressing any of the range of KRAS mutations
56 citations
TL;DR: It is reported that Ser22-phosphorylated Lamin A/C was localized to the nuclear interior in human fibroblasts throughout the cell cycle and suggested that LaminA/C regulates gene expression by enhancer binding, which may underlie the pathogenesis of disorders caused by LMNA mutations.
53 citations