Publications by Ayyakkannu Ayyanan

Estrogen receptor positive breast cancers have patient specific hormone sensitivities and rely on progesterone receptor

Cathrin Brisken, Giovanna Ambrosini, Ayyakkannu Ayyanan, Laura Battista, Valentina Scabia, Csaba Ferenc László, Fabio De Martino, Andrea Agnoletto

Estrogen and progesterone receptor (ER, PR) signaling control breast development and impinge on breast carcinogenesis. ER is an established driver of ER + disease but the role of the PR, itself an ER target gene, is debated. We assess the issue in clinical ...

Nature Portfolio2022

RNA sequencing-based single sample predictors of molecular subtype and risk of recurrence for clinical assessment of early-stage breast cancer

Cathrin Brisken, Ayyakkannu Ayyanan, Rachel Marcone

Multigene assays for molecular subtypes and biomarkers can aid management of early invasive breast cancer. Using RNA-sequencing we aimed to develop single-sample predictor (SSP) models for clinical markers, subtypes, and risk of recurrence (ROR). A cohort ...

NATURE PORTFOLIO2022

Intraductal xenografts show lobular carcinoma cells rely on their own extracellular matrix and LOXL1

Philipp Bucher, Cathrin Brisken, Giovanna Ambrosini, Ayyakkannu Ayyanan, Laura Battista, Georgios Sflomos, Valentina Scabia, Maryse Fiche, Patrik Aouad, Fabio De Martino

Invasive lobular carcinoma (ILC) is the most frequent special histological subtype of breast cancer, typically characterized by loss of E‐cadherin. It has clinical features distinct from other estrogen receptor‐positive (ER+) breast cancers but the molecul ...

2021

Intraductal patient-derived xenografts of estrogen receptor α-positive breast cancer recapitulate the histopathological spectrum and metastatic potential of human lesions

Cathrin Brisken, Ayyakkannu Ayyanan, Laura Battista, Georgios Sflomos, Valentina Scabia, Valérian Charles Robert Dormoy, Maryse Fiche, Patrik Aouad

Estrogen receptor α-positive (ER-positive) or 'luminal' breast cancers were notoriously difficult to establish as patient-derived xenografts (PDXs). We and others recently demonstrated that the microenvironment is critical for ER-positive tumor cells; when ...

2018

Oestrogen receptor alpha AF-1 and AF-2 domains have cell population-specific functions in the mammary epithelium

Cathrin Brisken, Ayyakkannu Ayyanan, Georgios Sflomos, Valentina Scabia, Dalya Ataca, Stéphanie Cagnet, Patrik Aouad

Oestrogen receptor alpha (ER alpha) is a transcription factor with ligand-independent and ligand-dependent activation functions (AF)-1 and -2. Oestrogens control postnatal mammary gland development acting on a subset of mammary epithelial cells (MECs), ter ...

Nature Publishing Group2018

A Preclinical Model for ERα-Positive Breast Cancer Points to the Epithelial Microenvironment as Determinant of Luminal Phenotype and Hormone Response

Cathrin Brisken, Ayyakkannu Ayyanan, Laura Battista, Rachel Marcone, Georgios Sflomos, Valentina Scabia, Valérian Charles Robert Dormoy, Maryse Fiche

Seventy-five percent of breast cancers are estrogen receptor α positive (ER(+)). Research on these tumors is hampered by lack of adequate in vivo models; cell line xenografts require non-physiological hormone supplements, and patient-derived xenografts (PD ...

Elsevier2016

Progesterone and Wnt4 control mammary stem cells via myoepithelial crosstalk

Cathrin Brisken, Renuga Devi Rajaram, Ayyakkannu Ayyanan, Jacques Rougemont, Marian Caikovski, Duje Buric

Ovarian hormones increase breast cancer risk by poorly understood mechanisms. We assess the role of progesterone on global stem cell function by serially transplanting mouse mammary epithelia. Progesterone receptor (PR) deletion severely reduces the regene ...

Wiley-Blackwell2015

Progesterone/RANKL Is a Major Regulatory Axis in the Human Breast

Cathrin Brisken, Ayyakkannu Ayyanan, Maria Gutierrez Najera, Tamara Tanos, Georgios Sflomos, Maryse Fiche

Estrogens and progesterones are major drivers of breast development but also promote carcinogenesis in this organ. Yet, their respective roles and the mechanisms underlying their action in the human breast are unclear. Receptor activator of nuclear factor ...

American Association for the Advancement of Science2013

Perinatal Exposure to Bisphenol A Increases Adult Mammary Gland Progesterone Response and Cell Number

Cathrin Brisken, Ayyakkannu Ayyanan, Jacques Rougemont, Tamara Tanos, Christina Schrick

Bisphenol A [BPA, 2,2,-bis (hydroxyphenyl) propane] is one of the highest-volume chemicals produced worldwide. It is detected in body fluids of more than 90% of the human population. Originally synthesized as an estrogenic compound, it is currently utilize ...

Endocrine Society2011

Two distinct mechanisms underlie progesterone-induced proliferation in the mammary gland

Cathrin Brisken, Ayyakkannu Ayyanan, Marian Caikovski

The mouse mammary gland develops postnatally under the control of female reproductive hormones. Estrogens and progesterone trigger morphogenesis by poorly understood mechanisms acting on a subset of mammary epithelial cells (MECs) that express their cognat ...

National Academy of Sciences2010

Epithelial-Mesenchymal Transition-Derived Cells Exhibit Multi-Lineage Differentiation Potential Similar to Mesenchymal Stem Cells

Cathrin Brisken, Ayyakkannu Ayyanan

The epithelial-to-mesenchymal transition (EMT) is an embryonic process that becomes latent in most normal adult tissues. Recently, we have shown that induction of EMT endows breast epithelial cells with stem cell traits. In this report, we have further cha ...

2010

The epithelial-mesenchymal transition generates cells with properties of stem cells

Cathrin Brisken, Ayyakkannu Ayyanan, Jiangyan Yang

The epithelial-mesenchymal transition (EMT) is a key developmental program that is often activated during cancer invasion and metastasis. We here report that the induction of an EMT in immortalized human mammary epithelial cells (HMLEs) results in the acqu ...

2008