The neural crest is a multipotent, migratory cell population that contributes to a variety of tissues and organs during vertebrate embryogenesis. Here, we focus on the function of Msx1 and Msx2, homeobox genes implicated in several disorders affecting craniofacial development in humans. We show that Msx1/2mutants exhibit profound deficiencies in the development of structures derived from the cranial and cardiac neural crest. These include hypoplastic and mispatterned cranial ganglia, dysmorphogenesis of pharyngeal arch derivatives and abnormal organization of conotruncal structures in the developing heart. The expression of the neural crest markers Ap-2α, Sox10 and cadherin 6 (cdh6) in Msx1/2mutants revealed an apparent retardation in the migration of subpopulations of preotic and postotic neural crest cells, and a disorganization of neural crest cells paralleling patterning defects in cranial nerves. In addition, normally distinct subpopulations of migrating crest underwent mixing. The expression of the hindbrain markers Krox20 and Epha4 was altered in Msx1/2 mutants, suggesting that defects in neural crest populations may result, in part, from defects in rhombomere identity. Msx1/2 mutants also exhibited increased Bmp4expression in migratory cranial neural crest and pharyngeal arches. Finally,proliferation of neural crest-derived mesenchyme was unchanged, but the number of apoptotic cells was increased substantially in neural crest-derived cells that contribute to the cranial ganglia and the first pharyngeal arch. This increase in apoptosis may contribute to the mispatterning of the cranial ganglia and the hypoplasia of the first arch.

reporter showed β-galactosidase activity exclusively in granulosa cells (Figure 1).

The Notch pathway is crucial for a wide variety of developmental processes including the formation of tissue boundaries. That it may function in calvarial suture development and figure in the pathophysiology of craniosynostosis was suggested by the demonstration that heterozygous loss of function of JAGGED1 in humans can cause Alagille syndrome, which has craniosynostosis as a feature. We used conditional gene targeting to examine the role of Jagged1 in the development of the skull vault. We demonstrate that Jagged1 is expressed in a layer of mesoderm-derived sutural cells that lie along the osteogenic-non-osteogenic boundary. We show that inactivation of Jagged1 in the mesodermal compartment of the coronal suture, but not in the neural crest compartment, results in craniosynostosis. Mesodermal inactivation of Jagged1 also results in changes in the identity of sutural cells prior to overt osteogenic differentiation, as well as defects in the boundary between osteogenic and non-osteogenic compartments at the coronal suture. These changes, surprisingly, are associated with increased expression of Notch2 and the Notch effector, Hes1, in the sutural mesenchyme. They are also associated with an increase in nuclear β-catenin. In Twist1 mutants, Jagged1 expression in the suture is reduced substantially, suggesting an epistatic relationship between Twist1 and Jagged1. Consistent with such a relationship, Twist1-Jagged1 double heterozygotes exhibit a substantial increase in the severity of craniosynostosis over individual heterozygotes. Our results thus suggest that Jagged1 is an effector of Twist1 in coronal suture development.

Menstrual cycle activity is the most important risk factor for sporadic serous ovarian carcinoma while a germline mutation in BRCA1 is the most important risk factor for the familial form. Given the rarity of BRCA1 mutations in sporadic ovarian cancers, we hypothesized that BRCA1 influences the menstrual cycle in a way that mimics the factors underlying sporadic ovarian cancer predisposition, making BRCA1 mutations redundant in such cancers. We compared the length of each phase of the estrus cycle (equivalent to the human menstrual cycle) and of circulating levels of estradiol in control mice and in mice carrying a Brca1 mutation in their ovarian granulosa cells, two thirds of which develop ovarian or uterine epithelial tumors. We also compared the length of the different phases of the cycle in mutants that subsequently developed tumors to those in mutants remained tumor free. Mutant mice as well as or oophorectomized wild type mice harboring mutant ovarian grafts showed a relative increase in the average length of the proestrus phase of the estrus cycle, which corresponds to the estrogen-dominated follicular phase of the human menstrual cycle. Total circulating levels of estradiol were also increased in mutant mice injected with pregnant mare serum gonadotropins. The relative increase in proestrus length was highest in mutant mice that subsequently developed reproductive epithelial tumors. We conclude that loss of a functional Brca1 increases murine ovarian epithelial tumor predisposition by increasing estrogen stimulation in the absence of progesterone, recapitulating conditions associated with sporadic ovarian cancer predisposition in humans.

Background:Axl plays multiple roles in tumourigenesis in several cancers. Here we evaluated the expression and biological function of Axl in renal cell carcinoma (RCC).Methods:Axl expression was analysed in a tissue microarray of 174 RCC samples by immunostaining and a panel of 11 normal tumour pairs of human RCC tissues by western blot, as well as in RCC cell lines by both western blot and quantitative PCR. The effects of Axl knockdown in RCC cells on cell growth and signalling were investigated. The efficacy of a humanised Axl targeting monoclonal antibody hMAb173 was tested in histoculture and tumour xenograft.Results:We have determined by immunohistochemistry (IHC) that Axl is expressed in 59% of RCC array samples with moderate to high in 20% but not expressed in normal kidney tissue. Western blot analysis of 11 pairs of tumour and adjacent normal tissue show high Axl expression in 73% of the tumours but not normal tissue. Axl is also expressed in RCC cell lines in which Axl knockdown reduces cell viability and PI3K/Akt signalling. The Axl antibody hMAb173 significantly induced RCC cell apoptosis in histoculture and inhibited the growth of RCC tumour in vivo by 78%. The hMAb173-treated tumours also had significantly reduced Axl protein levels, inhibited PI3K signalling, decreased proliferation, and induced apoptosis.Conclusions:Axl is highly expressed in RCC and critical for RCC cell survival. Targeting Axl is a potential approach for RCC treatment.

Rates of the most common gynecologic cancer, endometrioid adenocarcinoma (EAC), continue to rise, mirroring the global epidemic of obesity, a well-known EAC risk factor. Thus, identifying novel molecular targets to prevent and/or mitigate EAC is imperative. The prevalent Type 1 EAC commonly harbors loss of the tumor suppressor, Pten, leading to AKT activation. The major endoplasmic reticulum (ER) chaperone, GRP78, is a potent pro-survival protein to maintain ER homeostasis, and as a cell surface protein, is known to regulate the PI3K/AKT pathway. To determine whether targeting GRP78 could suppress EAC development, we created a conditional knockout mouse model utilizing progesterone receptor (PR)-Cre-recombinase to achieve Pten and Grp78 (cPtenf/fGrp78f/f) deletion in the endometrial epithelium. Mice with a single Pten (cPtenf/f) deletion developed well-differentiated EAC by 4 weeks. In contrast, no cPtenf/fGrp78f/f mice developed EAC, even after more than 8 months of observation. Histologic examination of uteri from cPtenf/fGrp78f/f mice also revealed no complex atypical hyperplasia (CAH), a well-established EAC precursor. These histologic observations among the cPtenf/fGrp78f/f murine uteri also corresponded to abrogation of AKT activation within the endometrium. We further observed that GRP78 co-localized with activated AKT on the surface of EAC thus providing an opportunity for therapeutic targeting. Consistent with previous findings that cell surface GRP78 is an upstream regulator of PI3K/AKT signaling, we show here that in vivo short-term systemic treatment with a highly specific monoclonal antibody against GRP78 suppressed AKT activation and increased apoptosis in the cPtenf/f tumors. Collectively, these findings present GRP78-targeting therapy as an efficacious therapeutic option for EAC.

Incessant menstrual cycle activity, uninterrupted by either pregnancy or oral contraceptive use, is the most important risk factor for sporadic ovarian cancer. Menstrual cycle progression is partly controlled by steroid hormones such as estrogens and others that are secreted by ovarian granulosa cells. We showed earlier that mice carrying a homozygous granulosa cell specific knock out of Brca1, the homolog of BRCA1that is associated with familial ovarian cancer predisposition in humans, develop benign epithelial tumors in their reproductive tract. These tumors are driven, at least in part, by a prolongation of the proestrus phase of the estrus cycle (equivalent to the follicular phase of the menstrual cycle) in Brca1 mutant mice, resulting in prolonged unopposed estrogen stimulation. Mutant mice synchronized in proestrus also showed increased circulating estradiol levels, but the possibility that this changealso plays a role in tumor predisposition was not investigated. We sought to determine whether these changes in hormonal stimulation result in measurable changes in tissues targeted by estrogen outside the ovary. Here we show that mice carrying a Brca1 mutation in ovarian granulosa cells show increased endometrial proliferation during proestrus, implying that the effects of Brca1 inactivation on estrogen stimulation have short-term consequences, at least on this target organ. We further show that mutant mice develop increased femoral trabecular thickness and femoral length, which are well-known consequences of chronic estrogen stimulation. Estrogen biosynthesis by granulosa cells was increased not only in mice carrying a homozygous Brca1 mutation, but also in heterozygous mutants mimicking the mutational status in granulosa cells of human BRCA1 mutation carriers. The results suggestthat humangermline BRCA1 mutations, although associated with increased cancer risk, may also have beneficial consequences, such as increased bone strength, that may have contributed to the maintenance of mutated BRCA1 alleles in the human gene pool.

Whereas Jagged1-Notch2 signaling is known to pattern the sensorineural components of the inner ear, its role in middle ear development has been less clear. We previously reported a role for Jagged-Notch signaling in shaping skeletal elements derived from the first two pharyngeal arches of zebrafish. Here we show a conserved requirement for Jagged1-Notch2 signaling in patterning the stapes and incus middle ear bones derived from the equivalent pharyngeal arches of mammals. Mice lacking Jagged1 or Notch2 in neural crest-derived cells (NCCs) of the pharyngeal arches display a malformed stapes. Heterozygous Jagged1 knockout mice, a model for Alagille Syndrome (AGS), also display stapes and incus defects. We find that Jagged1-Notch2 signaling functions early to pattern the stapes cartilage template, with stapes malformations correlating with hearing loss across all frequencies. We observe similar stapes defects and hearing loss in one patient with heterozygous JAGGED1 loss, and a diversity of conductive and sensorineural hearing loss in nearly half of AGS patients, many of which carry JAGGED1 mutations. Our findings reveal deep conservation of Jagged1-Notch2 signaling in patterning the pharyngeal arches from fish to mouse to man, despite the very different functions of their skeletal derivatives in jaw support and sound transduction.