Biology subjects

Rannikmae, H.

Publications and source records attributed to Rannikmae, H..

3 recordsLinked to original sources

bioRxiv2022

Shared requirement for MYC upstream super-enhancer in tissue regeneration and cancer

Cancer has been characterized as a wound that does not heal. Malignant cells are morphologically distinct from normal proliferating cells, but have extensive similarities to tissues undergoing wound healing and/or regeneration. The mechanistic basis of this similarity has, however, remained enigmatic. Here we show that the genomic region upstream of Myc, which is required for intestinal tumorigenesis, is also required for intestinal regeneration after radiation damage. The region is also critical for growth of adult intestinal cells in 3D organoid culture, indicating that culture conditions that recapitulate most aspects of normal tissue architecture still reprogram normal cells to proliferate using a mechanism similar to that employed by cancer cells. Our results uncover a genetic link between tissue regeneration and tumorigenesis, and establish that normal tissue renewal and regeneration of tissues after severe damage are mechanistically distinct. SummaryMyc regulatory region links regeneration and cancer

cancer biology↗

bioRxiv2022

A Scalable 3D High-Content Imaging Protocol for Measuring a Drug Induced DNA Damage Response Using Immunofluorescent Sub-nuclear γH2AX Spots in Patient Derived Ovarian Cancer Organoids

The high morbidity rate of ovarian cancer has remained unchanged during the past four decades, partly due to lack of understanding of disease mechanisms and difficulties in developing new targeted therapies. Defective DNA damage detection and repair is one of the hallmarks of cancer cells and is a defining characteristic of ovarian cancer. Most in vitro studies to date, involve viability measurements at scale using relevant cancer cell lines, however, the translation to clinic is often lacking. The use of patient derived organoids is closing that translational gap yet the 3D nature of organoid cultures present challenges for assay measurements beyond viability measurements. In particular, high-content imaging has the potential for screening at scale providing a better understanding of mechanism of action of drugs or genetic perturbagens. In this study we report a semi-automated and scalable immunofluorescence imaging assay utilising the development of a 384-well plate based subnuclear staining and clearing protocol and optimisation of 3D confocal image analysis for studying DNA damage dose response in human ovarian cancer organoids. The assay was validated in four organoid models and demonstrated a predictable response to Etoposide drug treatment with lowest efficacy observed in the clinically most resistant model. This imaging and analysis method can be applied to other 3D organoid and spheroid models for use in high content screening.

bioinformatics↗

bioRxiv2020

Mutational inactivation of Apc in the intestinal epithelia compromises cellular organisation

The tumour suppressor adenomatous polyposis coli (Apc) regulates diverse effector pathways essential for cellular homeostasis. Truncating mutations in Apc, leading to the loss of its Wnt pathway and microtubule regulatory domains, are oncogenic in human and murine intestinal epithelia and drive malignant transformation. Whereas uncontrolled proliferation via Wnt pathway deregulation is an unequivocal consequence of oncogenic Apc mutations, it is not known whether loss of its other control systems contribute to tumorigenesis. Here we employ in vitro models of tumorigenesis to unmask the molecular barriers erected by Apc that maintain normal epithelial homeostasis in the murine intestinal epithelia. We determine that (i) enterocyte proliferation, (ii) microtubule dynamics and (iii) epithelial morphology are controlled by three independent molecular pathways, each corrupted by oncogenic Apc mutations. The key result of the study is to establish that Apc regulates three individual biological fates in the intestinal epithelia, through three distinct effector pathways, a significant advance to our understanding of normal tissue homeostasis, the molecular architecture of epithelial tissue and the aetiology of intestinal cancer.

cell biology↗