Hyperpolarization-activated cyclic-nucleotide gated channel (HCN) proteins are important regulators of both neuronal and cardiac excitability. Among the 4 HCN isoforms, HCN4 is known as a pacemaker channel, because it helps control the periodicity of contractions in vertebrate hearts. Although the physiological role of HCN4 channel has been studied in adult mammalian hearts, an earlier role during embryogenesis has not been clearly established. Here, we probe the embryonic roles of HCN4 channels, providing the first characterization of the expression profile of any of the HCN isoforms during Xenopus laevis development and investigate the consequences of altering HCN4 function on embryonic pattern formation. We demonstrate that both overexpression of HCN4 and injection of dominant-negative HCN4 mRNA during early embryogenesis results in improper expression of key patterning genes and severely malformed hearts. Our results suggest that HCN4 serves to coordinate morphogenetic control factors that provide positional information during heart morphogenesis in Xenopus.

Melanoma susceptibility differs significantly in male versus female populations. Low levels of androgen receptor (AR) in melanocytes of the two sexes are accompanied by heterogeneous expression at various stages of the disease. Irrespective of expression levels, genetic and pharmacological suppression of AR activity in melanoma cells blunts proliferation and induces senescence, while increased AR expression or activation exert opposite effects. AR down-modulation elicits a shared gene expression signature associated with better patient survival, related to interferon and cytokine signaling and DNA damage/repair. AR loss leads to dsDNA breakage, cytoplasmic leakage, and STING activation, with AR anchoring the DNA repair proteins Ku70/Ku80 to RNA Pol II and preventing RNA Pol II–associated DNA damage. AR down-modulation or pharmacological inhibition suppresses melanomagenesis, with increased intratumoral infiltration of macrophages and, in an immune-competent mouse model, cytotoxic T cells. AR provides an attractive target for improved management of melanoma independent of patient sex.

36Melanoma is a benchmark of major clinical significance for cancer development with greater 37 aggressiveness in the male than the female population. Surprisingly little is known on the role 38 of androgen receptor (AR) signaling in the disease. Irrespectively of expression levels, genetic 39 and pharmacological suppression of AR activity in a large panel of melanoma cells, derived 40 from both male and female patients, suppresses proliferation and self-renewal potential while, 41 conversely, increased AR expression or ligand stimulation enhance proliferation. AR gene 42 silencing in multiple melanoma lines elicits a shared gene expression signature related to 43 interferon-and inflammatory cytokines signaling with an inverse association with DNA repair-44 associated genes, which is significantly linked with better patients' survival. AR plays an 45 essential function in maintenance of genome integrity: in both cultured melanoma cells and 46 tumors, loss of AR activity leads to chromosomal DNA breakage, leakage into the cytoplasm, 47 and stimulator of interferon genes (STING) activation. In vivo, reduced tumorigenesis 48 resulting from AR gene silencing or pharmacological inhibition is associated with intratumor 49 macrophage infiltration and, in an immune competent mouse model, cytotoxic T cell 50 activation. Although at different levels, androgens are produced in both male and female 51 individuals and AR targeting provides an attractive therapy approach for improved 52 management of melanoma irrespective of patients' sex and gender. 53 54 Significance 55The study uncovers an essential role of androgen receptor (AR) signaling in melanoma cell 56 expansion and tumorigenesis, with loss of AR activity inducing cellular senescence, genomic 57 DNA breakage, a STING dependent inflammatory cascade and immune cells recruitment. Use 58 of AR inhibitors as growth inhibitory and DNA damaging agents in melanoma cells can 59 provide an attractive venue for new combination approaches for management of the disease. 60 61 Malignant melanoma is the fifth-most common cancer in the world, and its incidence 62 is rising. Among the many prognostic risk factors that have been proposed for the disease, one 63 of the most intriguing and less understood is sex (1). In fact, melanoma is an example of 64 primary clinical significance for investigating sex-related differences in cancer incidence and 65 survival, with the male population having greater susceptibility than the female, across all ages 66(1). Although differences in lifestyle and behavior may explain the delay and higher disease 67 stage in men at diagnosis, the female survival advantage persists even after adjusting for these 68 and additional variables (histological subtypes, Breslow thickness, body site) (2, 3). 69Differences in sex hormone levels and their downstream pathways play a key role in 70 sexual dimorphism in multiple cancer types (4), including melanoma (1). As for sexual 71 dimorphism in other cancer types (4), even for susceptibility to melanoma differences i...