Sex differences in cancer mechanisms

We now know that cancer is many different diseases, with great variation even within a single histological subtype. With the current emphasis on developing personalized approaches to cancer treatment, it is astonishing that we have not yet systematically incorporated the biology of sex differences into our paradigms for laboratory and clinical cancer research. While some sex differences in cancer arise through the actions of circulating sex hormones, other sex differences are independent of estrogen, testosterone, or progesterone levels. Instead, these differences are the result of sexual differentiation, a process that involves genetic and epigenetic mechanisms, in addition to acute sex hormone actions. Sexual differentiation begins with fertilization and continues beyond menopause. It affects virtually every body system, resulting in marked sex differences in such areas as growth, lifespan, metabolism, and immunity, all of which can impact on cancer progression, treatment response, and survival. These organismal level differences have correlates at the cellular level, and thus, males and females can fundamentally differ in their protections and vulnerabilities to cancer, from cellular transformation through all stages of progression, spread, and response to treatment. Our goal in this review is to cover some of the robust sex differences that exist in core cancer pathways and to make the case for inclusion of sex as a biological variable in all laboratory and clinical cancer research. We finish with a discussion of lab- and clinic-based experimental design that should be used when testing whether sex matters and the appropriate statistical models to apply in data analysis for rigorous evaluations of potential sex effects. It is our goal to facilitate the evaluation of sex differences in cancer in order to improve outcomes for all patients

Gonadal sex patterns p21-induced cellular senescence in mouse and human glioblastoma

Males exhibit higher incidence and worse prognosis for the majority of cancers, including glioblastoma (GBM). Disparate survival may be related to sex-biased responses to treatment, including radiation. Using a mouse model of GBM, we show that female cells are more sensitive to radiation, and that senescence represents a major component of the radiation therapeutic response in both sexes. Correlation analyses revealed that the CDK inhibitor p21 and irradiation induced senescence were differentially regulated between male and female cells. Indeed, female cellular senescence was more sensitive to changes in p21 levels, a finding that was observed in wildtype and transformed murine astrocytes, as well as patient-derived GBM cell lines. Using a novel Four Core Genotypes model of GBM, we further show that sex differences in p21-induced senescence are patterned during early development by gonadal sex. These data provide a rationale for the further study of sex differences in radiation response and how senescence might be enhanced for radiation sensitization. The determination that p21 and gonadal sex are required for sex differences in radiation response will serve as a foundation for these future mechanistic studies

Multi-Scalar Contributions to Sex Differences in Brain Tumor Incidence and Outcome

Nearly all complex human diseases exhibit some degree of sex difference in incidence, age of onset, disease severity, and/or response to treatment. Sex differences are observed in a wide range of nervous system disorders, including neurodevelopmental disorders, psychiatric diseases, neuroimmunological disorders, neurodegenerative diseases, and central nervous system (CNS) tumors. Males have increased incidence rates for most CNS tumor types. Sex differences in brain tumor incidence rates are observed in studies from around the world, across a wide range of cultures, in both pediatric and adult populations, and even extend to other species. Males also have decreased survival from brain tumors, both when comparing all brain tumors combined, and when looking specifically at the most common brain tumor types in both children and adults. The persistence of the male predominance in brain tumors across cultures, ages, and species strongly suggests that the sex differences observed stem from a biologic origin, rather than behavioral differences between men and women. While hormones can play a mechanistic role for some tumor histologies, the observation that sex differences in tumor incidence and outcome are present throughout the lifespan, even though hormone levels vary widely from childhood to old age, and are also observed in neutered and spayed dogs, clearly indicates a role for hormone-independent mechanisms. The male and female differences that underlie these mechanisms are established through sexual differentiation, the biological process by which males and females diverge physiologically from the undifferentiated zygote. Sexual differentiation begins at fertilization and continues throughout the lifespan; it involves genetic, epigenetic, metabolic, and hormonal mechanisms, and impacts virtually every body system. Since sex differences can be encoded at the genetic, cellular, tissue, and systemic level, investigating how sex influences health and disease requires a multi-scale approach. This work will describe three main projects, which together explore how male and female differences across these different scales contribute to sex differences in brain tumor risks and outcomes. The first project described will focus on the genetic/epigenetic scale, showing that male and female glioblastoma cells differ in the distribution of Brd4-bound active enhancers, which results in different transcriptional states and opposing effects of epigenetic drugs targeting Brd4. The second project will focus on the cellular scale; it shows that female glioblastoma cells are more sensitive to p21-induced cellular senescence following irradiation, and that sex differences in p21 sensitivity are patterned by exposure to gonadal hormones in utero. The third project will focus on the tissue scale, showing that brain tumors from women with previous pregnancies contain fetal microchimeric cells within the tumor microenvironment, a phenomenon unique to women, with potential implications for immune regulation and immunotherapy. As a whole, this body of work demonstrates how sex differences in brain tumor biology are encoded at every level, from the genetic scale to the systemic scale. As we move towards more personalized medicine approaches to treatment, it will be critical to incorporate sex in the design of clinical trials and in the implementation of therapies in clinical practice if we are to maximize treatment success for all patients, male and female

Sex and gonadal hormones in mouse models of Alzheimer¿s disease: what is relevant to the human condition?

Abstract Biologic sex and gonadal hormones matter in human aging and diseases of aging such as Alzheimer’s – and the importance of studying their influences relates directly to human health. The goal of this article is to review the literature to date on sex and hormones in mouse models of Alzheimer’s disease (AD) with an exclusive focus on interpreting the relevance of findings to the human condition. To this end, we highlight advances in AD and in sex and hormone biology, discuss what these advances mean for merging the two fields, review the current mouse model literature, raise major unresolved questions, and offer a research framework that incorporates human reproductive aging for future studies aimed at translational discoveries in this important area. Unraveling human relevant pathways in sex and hormone-based biology may ultimately pave the way to novel and urgently needed treatments for AD and other neurodegenerative diseases

Sex and gonadal hormones in mouse models of Alzheimer’s disease: what is relevant to the human condition?

Abstract Biologic sex and gonadal hormones matter in human aging and diseases of aging such as Alzheimer’s – and the importance of studying their influences relates directly to human health. The goal of this article is to review the literature to date on sex and hormones in mouse models of Alzheimer’s disease (AD) with an exclusive focus on interpreting the relevance of findings to the human condition. To this end, we highlight advances in AD and in sex and hormone biology, discuss what these advances mean for merging the two fields, review the current mouse model literature, raise major unresolved questions, and offer a research framework that incorporates human reproductive aging for future studies aimed at translational discoveries in this important area. Unraveling human relevant pathways in sex and hormone-based biology may ultimately pave the way to novel and urgently needed treatments for AD and other neurodegenerative diseases.</p

Ovarian Cycle Stages Modulate Alzheimer-Related Cognitive and Brain Network Alterations in Female Mice

International audienc

Life Extension Factor Klotho Prevents Mortality and Enhances Cognition in hAPP Transgenic Mice

Aging is the principal demographic risk factor for Alzheimer disease (AD), the most common neurodegenerative disorder. Klotho is a key modulator of the aging process and, when overexpressed, extends mammalian lifespan, increases synaptic plasticity, and enhances cognition. Whether klotho can counteract deficits related to neurodegenerative diseases, such as AD, is unknown. Here we show that elevating klotho expression decreases premature mortality and network dysfunction in human amyloid precursor protein (hAPP) transgenic mice, which simulate key aspects of AD. Increasing klotho levels prevented depletion of NMDA receptor (NMDAR) subunits in the hippocampus and enhanced spatial learning and memory in hAPP mice. Klotho elevation in hAPP mice increased the abundance of the GluN2B subunit of NMDAR in postsynaptic densities and NMDAR-dependent long-term potentiation, which is critical for learning and memory. Thus, increasing wild-type klotho levels or activities improves synaptic and cognitive functions, and may be of therapeutic benefit in AD and other cognitive disorders

Life extension factor klotho prevents mortality and enhances cognition in hAPP transgenic mice.

Aging is the principal demographic risk factor for Alzheimer disease (AD), the most common neurodegenerative disorder. Klotho is a key modulator of the aging process and, when overexpressed, extends mammalian lifespan, increases synaptic plasticity, and enhances cognition. Whether klotho can counteract deficits related to neurodegenerative diseases, such as AD, is unknown. Here we show that elevating klotho expression decreases premature mortality and network dysfunction in human amyloid precursor protein (hAPP) transgenic mice, which simulate key aspects of AD. Increasing klotho levels prevented depletion of NMDA receptor (NMDAR) subunits in the hippocampus and enhanced spatial learning and memory in hAPP mice. Klotho elevation in hAPP mice increased the abundance of the GluN2B subunit of NMDAR in postsynaptic densities and NMDAR-dependent long-term potentiation, which is critical for learning and memory. Thus, increasing wild-type klotho levels or activities improves synaptic and cognitive functions, and may be of therapeutic benefit in AD and other cognitive disorders