CRISPR/Cas9 mediated Y-chromosome elimination affects human cells transcriptome.

BACKGROUND: Sexual dimorphism represents a key concept in the comprehension of molecular processes guiding several sex-specific physiological and pathological mechanisms. It has been reported that genes involved in many disorders show a sex-dependent expression pattern. Moreover, the loss of Y chromosome (LOY), found to be a physiological age-driven phenomenon, has been linked to many neurodegenerative and autoimmune disorders, and to an increased cancer risk. These findings drove us towards the consideration that LOY may cause the de-regulation of disease specific networks, involving genes located in both autosomal and sex chromosomes. RESULTS: Exploiting the CRISPR/Cas9 and RNA-sequencing technologies, we generated a Y-deficient human cell line that has been investigated for its gene expression profile. Our results showed that LOY can influence the transcriptome displaying relevant enriched biological processes, such as cell migration regulation, angiogenesis and immune response. Interestingly, the ovarian follicle development pathway was found enriched, supporting the female-mimicking profile of male Y-depleted cells. CONCLUSION: This study, besides proposing a novel approach to investigate sex-biased physiological and pathological conditions, highlights new roles for the Y chromosome in the sexual dimorphism characterizing human health and diseases. Moreover, this analysis paves the way for the research of new therapeutic approaches for sex dimorphic and LOY-related diseases.

Sex specific regulation of TSPY-Like 2 in the DNA damage response of cancer cells.

Females have a lower probability to develop somatic cancers and a better response to chemotherapy than males. However, the reasons for these differences are still not well understood. The X-linked gene TSPY-Like 2 (TSPYL2) encodes for a putative tumor suppressor protein involved in cell cycle regulation and DNA damage response (DDR) pathways. Here, we demonstrate that in unstressed conditions TSPYL2 is maintained at low levels by MDM2-dependent ubiquitination and proteasome degradation. Upon genotoxic stress, E2F1 promotes TSPYL2 expression and protein accumulation in non-transformed cell lines. Conversely, in cancer cells, TSPYL2 accumulates only in females or in those male cancer cells that lost the Y-chromosome during the oncogenic process. Hence, we demonstrate that while TSPYL2 mRNA is induced in all the tested tumor cell lines after DNA damage, TSPYL2 protein stability is increased only in female cancer cells. Indeed, we found that TSPYL2 accumulation, in male cancer cells, is prevented by the Y-encoded protein SRY, which modulates MDM2 protein levels. In addition, we demonstrated that TSPYL2 accumulation is required to sustain cell growth arrest after DNA damage, possibly contributing to protect normal and female cancer cells from tumor progression. Accordingly, TSPYL2 has been found more frequently mutated in female-specific cancers. These findings demonstrate for the first time a sex-specific regulation of TSPYL2 in the DDR of cancer cells and confirm the existence of sexual dimorphism in DNA surveillance pathways.

Sex disparities in DNA damage response pathways: Novel determinants in cancer formation and therapy.

Cancer incidence and survival are different between men and women. Indeed, females have a lesser risk and a better prognosis than males in many tumors unrelated to reproductive functions. Although the reasons for these disparities are still unknown, they constitute an important starting point for the development of personalized cancer therapies. One of the mechanisms that fuels carcinogenesis is the accumulation of defects in DNA damage response (DDR) pathways, a complex signaling cascade that senses DNA lesions and, depending on the severity, coordinates transient cell-cycle arrest, DNA replication, repair, apoptosis, and senescence, preventing genomic instability and cancer. Recently, evidence of sexual dimorphisms is emerging in these pathways, therefore providing new opportunities for precision medicine. Here, we will discuss current knowledge about sexual disparities in the DDR, their role in tumorigenesis and cancer progression, and the importance of considering sex contribution in both research and cancer therapies.

Targeting Proliferating Cell Nuclear Antigen (PCNA) as an Effective Strategy to Inhibit Tumor Cell Proliferation.

Targeting highly proliferating cells is an important issue for many types of aggressive tumors. Proliferating Cell Nuclear Antigen (PCNA) is an essential protein that participates in a variety of processes of DNA metabolism, including DNA replication and repair, chromatin organization and transcription and sister chromatid cohesion. In addition, PCNA is involved in cell survival, and possibly in pathways of energy metabolism, such as glycolysis. Thus, the possibility of targeting this protein for chemotherapy against highly proliferating malignancies is under active investigation. Currently, approaches to treat cells with agents targeting PCNA rely on the use of small molecules or on peptides that either bind to PCNA, or act as a competitor of interacting partners. Here, we describe the status of the art in the development of agents targeting PCNA and discuss their application in different types of tumor cell lines and in animal model systems.