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.

The ability to control vascular endothelial growth factor (VEGF) signaling offers promising therapeutic potential for vascular diseases and cancer. Despite this promise, VEGF-targeted therapies are not clinically effective for many pathologies, such as breast cancer. VEGFR1 has recently emerged as a predictive biomarker for anti-VEGF efficacy, implying a functional VEGFR1 role beyond its classically defined decoy receptor status. Here we introduce a computational approach that accurately predicts cellular responses elicited via VEGFR1 signaling. Aligned with our model prediction, we show empirically that VEGFR1 promotes macrophage migration through PLC_γ and PI3K pathways and promotes macrophage proliferation through a PLC_γ pathway. These results provide new insight into the basic function of VEGFR1 signaling while offering a computational platform to quantify signaling of any receptor.

Deficient angiogenesis may contribute to worsen the prognosis of myocardial ischemia, peripheral arterial disease (PAD), ischemic stroke, etc. Dyslipidemic and inflammatory environments attenuate endothelial cells (ECs) proliferation and angiogenesis, worsening the prognosis of ischemia. Under these dyslipidemic and inflammatory environments ECs-caspase-1 becomes activated and induces inflammatory cell death that is defined as pyroptosis. However, the underlying mechanism that correlates caspase-1 activation with angiogenic impairment and prognosis of ischemia remains poorly defined. By using flow cytometric analysis, enzyme and receptor inhibitors and hind limb ischemia model in caspase-1 knock out (KO) mice, we examined our novel hypothesis: Inhibition of caspase-1 in ECs under dyslipidemic and inflammatory environments attenuates EC pyroptosis, improves EC survival mediated by vascular endothelial growth factor receptor 2 (VEGFR-2), angiogenesis and the prognosis of ischemia. We have made the following findings: Proatherogenic lipids induce higher caspase-1 activation in larger sizes of human aortic endothelial cells (HAECs) than in smaller sizes of HAECs; Proatherogenic lipids increase pyroptosis significantly more in smaller sizes of HAECs than in larger sizes of the cells;VEGFR-2 inhibition increases caspase-1 activation in HAECs induced by lysophosphatidylcholine (LPC) treatment; Caspase-1 activation inhibits VEGFR-2 expression; Caspase-1 inhibition improves the tube formation of LPC-treated HAECs; and Caspase-1 depletion improves angiogenesis and blood flow in mouse hind-limb ischemic tissues. Our results have demonstrated for the first time that inhibition of proatherogenic caspase-1 activation in ECs improves angiogenesis and the prognosis of ischemia.

Neuronal nicotinic acetylcholine (ACh) receptors are ligand-gated, cation-selective ion channels. Nicotinic receptors containing α4, α6, β2, and β3 subunits are expressed in midbrain dopaminergic neurons, and they are implicated in the response to smoked nicotine. Here, we have studied the cell biological and biophysical properties of receptors containing α6 and β3 subunits by using fluorescent proteins fused within the M3-M4 intracellular loop. Receptors containing fluorescently tagged β3 subunits were fully functional compared with receptors with untagged β3 subunits. We find that β3- and α6-containing receptors are highly expressed in neurons and that they colocalize with coexpressed, fluorescent α4 and β2 subunits in neuronal soma and dendrites. Förster resonance energy transfer (FRET) reveals efficient, specific assembly of β3 and α6 into nicotinic receptor pentamers of various subunit compositions. Using FRET, we demonstrate directly that only a single β3 subunit is incorporated into nicotinic acetylcholine receptors (nAChRs) containing this subunit, whereas multiple subunit stoichiometries exist for α4- and α6-containing receptors. Finally, we demonstrate that nicotinic ACh receptors are localized in distinct microdomains at or near the plasma membrane using total internal reflection fluorescence (TIRF) microscopy. We suggest that neurons contain large, intracellular pools of assembled, functional nicotinic receptors, which may provide them with the ability to rapidly up-regulate nicotinic responses to endogenous ligands such as ACh, or to exogenous agents such as nicotine. Furthermore, this report is the first to directly measure nAChR subunit stoichiometry using FRET and plasma membrane localization of α6- and β3-containing receptors using TIRF.

Nearly all studies of angiogenesis have focused on uni-family ligand-receptor binding, e.g., VEGFs bind to VEGF receptors, PDGFs bind to PDGF receptors, etc. The discovery of VEGF-PDGFRs binding challenges this paradigm and calls for investigation of other ligand-receptor binding possibilities. We utilized surface plasmon resonance to identify and measure PDGF-to-VEGFR binding rates, establishing cut-offs for binding and non-binding interactions. We quantified the kinetics of the recent VEGF-A:PDGFRβ interaction for the first time with K_D = 340 pM. We discovered new PDGF:VEGFR2 interactions with PDGF-AA:R2 K_D = 530 nM, PDGF-AB:R2 K_D = 110 pM, PDGF-BB:R2 K_D = 40 nM, and PDGF-CC:R2 K_D = 70 pM. We computationally predict that cross-family PDGF binding could contribute up to 96% of VEGFR2 ligation in healthy conditions and in cancer. Together the identification, quantification, and simulation of these novel cross-family interactions posits new mechanisms for understanding anti-angiogenic drug resistance and presents an expanded role of growth factor signaling with significance in health and disease.