Insights Into Mechanisms of Oriented Division From Studies in 3D Cellular Models

In multicellular organisms, epithelial cells are key elements of tissue organization. In developing tissues, cellular proliferation and differentiation are under the tight regulation of morphogenetic programs, that ensure the correct organ formation and functioning. In these processes, mitotic rates and division orientation are crucial in regulating the velocity and the timing of the forming tissue. Division orientation, specified by mitotic spindle placement with respect to epithelial apico-basal polarity, controls not only the partitioning of cellular components but also the positioning of the daughter cells within the tissue, and hence the contacts that daughter cells retain with the surrounding microenvironment. Daughter cells positioning is important to determine signal sensing and fate, and therefore the final function of the developing organ. In this review, we will discuss recent discoveries regarding the mechanistics of planar divisions in mammalian epithelial cells, summarizing technologies and model systems used to study oriented cell divisions in vitro such as three-dimensional cysts of immortalized cells and intestinal organoids. We also highlight how misorientation is corrected in vivo and in vitro, and how it might contribute to the onset of pathological conditions.

Recent Approaches to the Identification of Novel Microtubule-Targeting Agents

Microtubules are key components of the eukaryotic cytoskeleton with essential roles in cell division, intercellular transport, cell morphology, motility, and signal transduction. They are composed of protofilaments of heterodimers of α-tubulin and β-tubulin organized as rigid hollow cylinders that can assemble into large and dynamic intracellular structures. Consistent with their involvement in core cellular processes, affecting microtubule assembly results in cytotoxicity and cell death. For these reasons, microtubules are among the most important targets for the therapeutic treatment of several diseases, including cancer. The vast literature related to microtubule stabilizers and destabilizers has been reviewed extensively in recent years. Here we summarize recent experimental and computational approaches for the identification of novel tubulin modulators and delivery strategies. These include orphan small molecules, PROTACs as well as light-sensitive compounds that can be activated with high spatio-temporal accuracy and that represent promising tools for precision-targeted chemotherapy.

Engineering transplantable jejunal mucosal grafts using patient-derived organoids from children with intestinal failure

Intestinal failure, following extensive anatomical or functional loss of small intestine, has debilitating long-term consequences for children1. The priority of patient care is to increase the length of functional intestine, particularly the jejunum, to promote nutritional independence2. Here we construct autologous jejunal mucosal grafts using biomaterials from pediatric patients and show that patient-derived organoids can be expanded efficiently in vitro. In parallel, we generate decellularized human intestinal matrix with intact nanotopography, which forms biological scaffolds. Proteomic and Raman spectroscopy analyses reveal highly analogous biochemical profiles of human small intestine and colon scaffolds, indicating that they can be used interchangeably as platforms for intestinal engineering. Indeed, seeding of jejunal organoids onto either type of scaffold reliably reconstructs grafts that exhibit several aspects of physiological jejunal function and that survive to form luminal structures after transplantation into the kidney capsule or subcutaneous pockets of mice for up to 2 weeks. Our findings provide proof-of-concept data for engineering patient-specific jejunal grafts for children with intestinal failure, ultimately aiding in the restoration of nutritional autonomy.

Evaluation of variants in BRIP1, PALB2 and CHEK2 in a west of Ireland breast cancer cohort

Abstract #3092

Introduction
 Positive family history is the most important risk factor in breast cancer predisposition. Recent studies have identified variants in BRIP1, PALB2 and CHEK2, which have been proposed as breast cancer susceptibility genes conferring an increased relative risk of 2-4%.
 Aims
 To evaluate the role of the above variants in the West of Ireland population and to examine their potential clinical relevance.
 Methods
 Proposed candidate genetics variants in BRIP1, PALB2 and CHEK2 were interrogated in 192 patients with a high risk of familial breast cancer. Genescan analysis and direct sequencing were used to evaluate these variants. Where a variant was exhibited, it was then examined further in 990 sporadic breast cancer patients and 1016 matched non-cancer controls using KASPar genotyping technology.
 Results
 We demonstated mutations in BRIP1 and CHEK2 genes. 1 mutation was found in BRIP1 2392C→T in our 192 patients with a high risk of familial breast cancer. 5 breast cancer patients and 1 control exhibited a CHEK2110delC mutation within 990 breast cancer patients and 1016 matched non-cancer controls. Mutations previously demonstrated in PALB2 were not evident in 192 high risk patients.
 Conclusions
 We have confirmed the presence of variants in BRIP1 and CHEK2, candidate moderate penetrance genes, in breast cancer patients with a strong family history of breast cancer. This may have implications in clinical practice as our knowledge of these variants expands. The absense of PALB2 variants in patients at high genetic risk points to a low clinical significance. Our findings contribute to a better understanding of inherited breast cancer risk while helping to optimize future screening, therapeutic and prophylactic programs.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3092.