FGF mediated MAPK and PI3K/Akt Signals make distinct contributions to pluripotency and the establishment of Neural Crest

Early vertebrate embryos possess cells with the potential to generate all embryonic cell types. While this pluripotency is progressively lost as cells become lineage restricted, Neural Crest cells retain broad developmental potential. Here, we provide novel insights into signals essential for both pluripotency and neural crest formation in Xenopus. We show that FGF signaling controls a subset of genes expressed by pluripotent blastula cells, and find a striking switch in the signaling cascades activated by FGF signaling as cells lose pluripotency and commence lineage restriction. Pluripotent cells display and require Map Kinase signaling, whereas PI3 Kinase/Akt signals increase as developmental potential is restricted, and are required for transit to certain lineage restricted states. Importantly, retaining a high Map Kinase/low Akt signaling profile is essential for establishing Neural Crest stem cells. These findings shed important light on the signal-mediated control of pluripotency and the molecular mechanisms governing genesis of Neural Crest.

NEURODEVELOPMENT. Shared regulatory programs suggest retention of blastula-stage potential in neural crest cells

Neural crest cells, which are specific to vertebrates, arise in the ectoderm but can generate cell types that are typically categorized as mesodermal. This broad developmental potential persists past the time when most ectoderm-derived cells become lineage-restricted. The ability of neural crest to contribute mesodermal derivatives to the bauplan has raised questions about how this apparent gain in potential is achieved. Here, we describe shared molecular underpinnings of potency in neural crest and blastula cells. We show that in Xenopus, key neural crest regulatory factors are also expressed in blastula animal pole cells and promote pluripotency in both cell types. We suggest that neural crest cells may have evolved as a consequence of a subset of blastula cells retaining activity of the regulatory network underlying pluripotency.

Abstract 1476: Prostate cancer-associated fibroblasts secrete Annexin A1 that facilitates both generation of cancer stem cell-like cells (CSCs) from prostatic malignant epithelial cells and self-renewal/differentiation of CSCs

Previously we described epithelial cell lines (Hormones & Cancer. 1: 44-54, 2010), primary cultures of cancer-associated fibroblasts (CAFs) (Cancer Res. 68: 198-205, 2008) and a primary cancer stem cell (CSC) subpopulation (Cancer Res. 70: 7294-303, 2010), all derived from the cPten-/-L mouse model of prostate adenocarcinoma (Cancer Res. 67: 7525-33, 2007). Most notably, we described evidence that CAFs secrete factors that enhance both the stemness and growth potentials of the CSCs (Cancer Res. 70: 7294-303, 2010). We have now identified the phospholipid binding Annnexin A1 as one of the pertinent secreted factors. When a malignant epithelial cell line (cE1) derived from castration-resistant prostate cancer (CRPC) from the model was fractionated into three different subpopulations based on the levels of cell surface expression of Sca-1(S) and CD49f (C) antigens: SChi, SCme and SC− (high, medium and low expression of S and C, respectively), we found that SCme cells were preferentially susceptible to epithelial-mesenchymal transition (EMT)-like transformation when treated with conditioned medium (CM) from either CAF cultures or Annexin A1 mimetic peptide (Ac1-25). Furthermore, following EMT induction, these trans-differentiated cells acquired stem cell-like properties similar to the SChi group based on expression of S and C and statistically significant up-regulation of Oct4 (p<0.05), Sox2 (p<0.001) and Nanog (p<0.0001). When transplanted within collagen grafts under the renal capsule of Nod.Scid mice, CM- and Ac1-25-EMT-ed SCme cells were able to form invasive lesions in vivo displaying cells with expression of both basal (p63) and luminal (cytokeratin 8, CK8)) cell-specific markers, as compared to untreated control grafts, which lacked glandular structures and had reduced p63 positive cells. Another effect of Annexin A1 was unraveled when CSCs (Lin− SChi subpopulation) from the primary tumors of the model were exposed to Acl-25. In vitro spheroid formation assays showed that in the presence of Acl-25 single spheroids generated from the CSCs could form multiple substructures potentially resulting from activation of additional stem-like progenitors, each capable of forming a prostasphere while remaining attached to the original spheroid structure. Immunofluorescent staining of cryosectioned spheroids revealed the presence of p63+ basal cells and an expanded population of p63/CK8 double positive transit-amplifying cells. Together these results describe two ways in which Annexin A1 may play a role in the development of a more malignant and stem cell-enriched tumor phenotype, or, to hypothetically take it a step further, possibly two ways in which Annexin A1, present in the tumor microenvironment, can lead to an increase or maintenance of a cancer stem cell(-like) population.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1476. doi:1538-7445.AM2012-1476

Seatbelt use by high school students

OBJECTIVE

To determine seatbelt use of teenage drivers arriving at high schools in the morning and at evening football games compared with belt use of adults driving teenage passengers to these events, and teenage passenger belt use depending on whether they were being driven by another teenager or an adult.

METHODS

Unobtrusive observations of belt use were made at 12 high schools in Connecticut and Massachusetts.

RESULTS

Among males, teenage drivers had lower belt use than adults; differences between female teenage and female adult drivers were slight. Teenage passengers had lower belt use in vehicles driven by other teenagers than in cars driven by adults, but more than 40% of teenage passengers in vehicles driven by adults, presumed in most cases to be the teenager's parent, were not belted. Teenage passenger belt use was lower than teenage driver use regardless of gender. These differences were found both at morning arrivals and at football games, but teenage belt use was not much different in these two settings. Teenage passengers were belted more often if drivers were belted, whether the driver was another teenager or an adult, but a third of male passengers and 25%-30% of female passengers were unbelted even when drivers were belted.

CONCLUSION

Teenagers have high crash risk but low belt use, which adds to their injury problem. Avenues to address this include strong belt use laws and their enforcement, building belt use requirements into graduated licensing systems, keeping young beginners out of high risk driving situations, and finding ways to influence parents and other adults to ensure that their teenage passengers use seatbelts.

A preliminary study of patient comfort associated with customised mouthguards

OBJECTIVE

To compare patient perception of custom made mouthguards of ideal and less than ideal designs in terms of their comfort and "wearability".

METHOD

A mouthguard of ideal design (A) and one incorporating common design faults of underextension and unadjusted occlusion (B) were provided for 22 active sportsmen and women. They were not informed of the details of the design or the status of the protector. Half the participants were asked to wear mouthguard A first and the other half wore B first, each worn for one hour on two consecutive nights. Questionnaires were used to evaluate and rate the comfort and wearability of each mouthguard.

RESULTS

Eighteen people completed the study. The ideal appliance was rated as significantly more retentive and comfortable overall and specifically was more comfortable to lips, gums, and tongue. It was also recognised as being less bulky, less likely to keep the teeth apart, or to cause pain in the jaw muscles.

CONCLUSIONS

Comfort is likely to be increased if mouthguards are extended labially to within 2 mm of the vestibular reflection, adjusted to allow even occlusal contact, rounded at the buccal peripheries, and tapered at the palatal edges.

Retention of adhesive cement on the tooth surface after crown cementation

STATEMENT OF PROBLEM

Adhesive cements increase crown retention, but it is unknown if traces of cement remain undetected on the tooth surface after clinical removal of excess cement, which could exacerbate plaque retention.

PURPOSE

This study measured the surface area, volume, mean depth, and maximum depth of a resin composite and a compomer luting cement left adherent on the tooth surface after removal of excess cement, as judged clinically.

METHODS AND MATERIAL

Four groups of specimens (n = 48) were prepared for full coverage crowns: group AC bonding alloy with chamfer finish line, group G gold alloy with chamfer finish line, group PC porcelain with a chamfer finish line, and group PS porcelain with a shoulder finish line. Two profiles of the mesial and distal surfaces of the teeth were carried out: (1) tooth with crown seated but not cemented and (2) tooth with the crown cemented in place. Two cements and 2 methods of cement removal were studied.

RESULTS

A 4-way analysis of variance for cement, crown type, method of removal, and tooth surface morphology showed that significantly greater volumes and mean depth, but not surface areas, of resin composite cement remained adherent than compomer cement (P<.05). Among crown types, significant differences were found for cement volume (group G>AC, G>PC, G>PS), cement surface area (group AC>PC, G>PC, G>PS), and maximum cement depth (group G>AC). There was no significant difference between the 2 methods of cement removal. Significantly larger surface areas and maximum depths of cement were retained on the anatomically grooved mesial surface of the maxillary first premolars than on the ungrooved distal surface.

CONCLUSION

Subclinical cement retention occurred after crown cementation, which was influenced by cement, crown type, and tooth surface morphology but not method of cement removal.