Osteoporosis is a complex disease that affects >10 million people in the United States and results in 1.5 million fractures annually. In addition, the high prevalence of osteopenia (low bone mass) in the general population places a large number of people at risk for developing the disease. In an effort to identify genetic factors influencing bone density, we characterized a family that includes individuals who possess exceptionally dense bones but are otherwise phenotypically normal. This high-bone-mass trait (HBM) was originally localized by linkage analysis to chromosome 11q12-13. We refined the interval by extending the pedigree and genotyping additional markers. A systematic search for mutations that segregated with the HBM phenotype uncovered an amino acid change, in a predicted beta-propeller module of the low-density lipoprotein receptor-related protein 5 (LRP5), that results in the HBM phenotype. During analysis of >1,000 individuals, this mutation was observed only in affected individuals from the HBM kindred. By use of in situ hybridization to rat tibia, expression of LRP5 was detected in areas of bone involved in remodeling. Our findings suggest that the HBM mutation confers a unique osteogenic activity in bone remodeling, and this understanding may facilitate the development of novel therapies for the treatment of osteoporosis.

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.

No 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.

Mutant p53 proteins accumulate to high levels in human tumors and in preneoplastic lesions in the skin and fallopian tube. However examination of tissues from mice and fish that are homozygous for mutant p53 surprisingly showed that the protein was present only at low levels except in the tumors that arose in these animals. The mutant protein did accumulate, however, following treatment with ionizing radiation in the same tissues in which the wild-type protein is induced. Here we study in detail the accumulation of mutant and wild-type p53 proteins following ionizing radiation in zebrafish embryos. We found that the mutant protein was induced by lower levels of radiation and reached higher levels than the wild-type protein. Morpholino knockdown of the zebrafish homologs of Mdm2 and Mdm4 caused dramatic accumulation of mutant p53 protein. The most remarkable results were observed by examining p53 protein levels over an extended time course. Mutant p53 protein increased and persisted for days after irradiation and this was accompanied by persistent elevation of phosphorylated H2AX (γH2AX), implying that the resolution of DNA damage signaling in these embryos is severely compromised by mutations in p53. Thus mutation in p53 results in an exaggerated and persistent damage response, which could in turn drive the process of cancer development as high levels of mutant p53 can act as an oncoprotein to drive invasion and metastasis.