The Asymmetric Cell Division Regulators Par3, Scribble and Pins/Gpsm2 Are Not Essential for Erythroid Development or Enucleation

Erythroid enucleation is the process by which the future red blood cell disposes of its nucleus prior to entering the blood stream. This key event during red blood cell development has been likened to an asymmetric cell division (ACD), by which the enucleating erythroblast divides into two very different daughter cells of alternate molecular composition, a nucleated cell that will be removed by associated macrophages, and the reticulocyte that will mature to the definitive erythrocyte. Here we investigated gene expression of members of the Par, Scribble and Pins/Gpsm2 asymmetric cell division complexes in erythroid cells, and functionally tested their role in erythroid enucleation in vivo and ex vivo. Despite their roles in regulating ACD in other contexts, we found that these polarity regulators are not essential for erythroid enucleation, nor for erythroid development in vivo. Together our results put into question a role for cell polarity and asymmetric cell division in erythroid enucleation.

Abstract B48: The effects of different types of hypoxia on tumor progression in breast cancer

Hypoxia, the state of low oxygen conditions, occurs frequently in solid tumors and is a poor prognostic factor. The expression of Hif-1α,the main mediator of the hypoxic response pathway, and the subsequent up-regulation of its target genes have been implicated in tumor growth, invasion, angiogenesis, therapy resistance and metastasis. There are two forms of hypoxia present in a growing tumor: chronic hypoxia (caused by limitations in oxygen diffusion from abnormal tumor vasculature) and intermittent hypoxia (caused by the aberrant, repeated and temporary closing and re-opening of blood vessels, leading to fluctuations in oxygen supply). This study investigates the phenotypes endowed by different forms of hypoxia that mediate metastatic potential in a syngeneic mouse model of breast cancer.

By exposing murine breast cancer cells to 9 days of 20% O2 (normoxia), 1% O2 (chronic hypoxia) or alternating 24 hour cycles in 20% O2 and 1% O2 (intermittent hypoxia), we observe that intermittent hypoxia produces tumor cells with greater metastatic potential. These treatments produce no difference in primary tumor growth when orthotopically injected into the mammary fat pad of female C57Bl/6 mice. However, intermittent hypoxia-treated cells give rise to a greater number of and larger lung metastases when injected intravenously via the tail-vein of female C57Bl/6 mice. Intermittent hypoxia, but not chronic hypoxia, up-regulated the expression of genes that predict lung metastasis in breast cancer, endowed cells with an enhanced ability for anchorage-independent growth and produced greater clonal diversity. Furthermore, intermittent hypoxia also caused a switch to glycolysis in cells and induced a pro-tumorigenic, immunosuppressive secretory profile in vitro. Finally, intermittent hypoxia up-regulated the expression of mammary stem cell genes, increased expression of stem cell marker Sca-1 as well as CD14, and generated tumor-initiating cells at a higher frequency as evidenced by in vivo limiting dilution assays.

This work demonstrates that intermittent hypoxia enhances metastatic seeding and outgrowth by priming cells intrinsically to metastasize, while activating co-operating factors that act extrinsically to form a permissive, immunosuppressive microenvironment. By delineating the contributions of different forms of hypoxia to metastasis, critical molecular mediators can be identified in aid of the development of efficacious therapies that could inhibit, prevent or cure metastatic disease.

Citation Format: Anna Chen, Jaclyn Sceneay, Nathan Gödde, Erik Thompson, Patrick Humbert, Andreas Möller. The effects of different types of hypoxia on tumor progression in breast cancer. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr B48.

Colonic ischaemia as a severe Shiga toxin/verotoxin producing Escherichia coli O104:H4 complication in a patient without haemolytic uraemic syndrome, Germany, June 2011

An increasing rate of infections with Shiga toxin/verotoxin-producing Escherichia coli (STEC/VTEC) O104:H4 has been observed in Germany since May 2011, with unusually high numbers of patients suffering from haemolytic uraemic syndrome (HUS). We report a STEC/VTEC O104:H4 case without HUS, presenting with colonic ischaemia demanding surgery. This atypical clinical presentation of STEC O104:H4 infection might indicate new severe complications associated with this uncommon strain, and highlights the importance of immediate interdisciplinary assessment of STEC/VTEC patients.

Colonic ischaemia as a severe Shiga toxin/verotoxin producing Escherichia coli O104:H4 complication in a patient without haemolytic uraemic syndrome, Germany, June 2011

An increasing rate of infections with Shiga toxin/verotoxin-producing Escherichia coli (STEC/VTEC) O104:H4 has been observed in Germany since May 2011, with unusually high numbers of patients suffering from haemolytic uraemic syndrome (HUS). We report a STEC/VTEC O104:H4 case without HUS, presenting with colonic ischaemia demanding surgery. This atypical clinical presentation of STEC O104:H4 infection might indicate new severe complications associated with this uncommon strain, and highlights the importance of immediate interdisciplinary assessment of STEC/VTEC patients.