SUMMARY Despite the importance of programmed cell death-1 (PD-1) in inhibiting T cell effector activity, the mechanisms regulating its expression remain poorly defined. We found that the chromatin organizer special AT-rich sequence-binding protein-1 (Satb1) restrains PD-1 expression induced upon T cell activation by recruiting a nucleosome remodeling deacetylase (NuRD) complex to Pdcd1 regulatory regions. Satb1 deficienct T cells exhibited a 40-fold increase in PD-1 expression. Tumor-derived Transforming Growth Factor β (Tgf-β) decreased Satb1 expression through binding of Smad proteins to the Satb1 promoter. Smad proteins also competed with the Satb1-NuRD complex for binding to Pdcd1 enhancers, releasing Pdcd1 expression from Satb1-mediated repression, Satb1-deficient tumor-reactive T cells lost effector activity more rapidly than wild-type lymphocytes at tumor beds expressing PD-1 ligand (CD274), and these differences were abrogated by sustained CD274 blockade. Our findings suggest that Satb1 functions to prevent premature T cell exhaustion by regulating Pdcd1 expression upon T cell activation. Dysregulation of this pathway in tumor-infiltrating T cells results in diminished anti-tumor immunity.

Epithelial ovarian cancer (EOC) is the most lethal of gynecologic malignancies. The standard-of-care treatment for EOC is platinumbased chemotherapy such as cisplatin. Platinum-based chemotherapy induces cellular senescence. Notably, therapy-induced senescence contributes to chemoresistance by inducing cancer stem-like cells (CSC). However, therapeutic approaches targeting senescenceassociated CSCs remain to be explored. Here, we show that nicotinamide phosphoribosyltransferase (NAMPT) inhibition suppresses senescence-associated CSCs induced by platinum-based chemotherapy in EOC. Clinically applicable NAMPT inhibitors suppressed the outgrowth of cisplatin-treated EOC cells both in vitro and in vivo. Moreover, a combination of the NAMPT inhibitor FK866 and cisplatin improved the survival of EOCbearing mice. These phenotypes correlated with inhibition of the CSCs signature, which consists of elevated expression of ALDH1A1 and stem-related genes, high aldehyde dehydrogenase activity, and CD133 positivity. Mechanistically, NAMPT regulates EOC CSCs in a paracrine manner through the senescence-associated secretory phenotype. Our results suggest that targeting NAMPT using clinically applicable NAMPT inhibitors, such as FK866, in conjunction with platinum-based chemotherapy represents a promising therapeutic strategy by suppressing therapy-induced senescenceassociated CSCs.Significance: This study highlights the importance of NAMPTmediated NAD þ biosynthesis in the production of cisplatininduced senescence-associated cancer stem cells, as well as tumor relapse after cisplatin treatment.

Mortality from ovarian cancer may be dramatically reduced with the implementation of attainable prevention strategies. The new understanding of the cells of origin and the molecular etiology of ovarian cancer warrants a strong recommendation to the public and health care providers. This document discusses potential prevention strategies, which include 1) oral contraceptive use, 2) tubal sterilization, 3) risk-reducing salpingo-oophorectomy in women at high hereditary risk of breast and ovarian cancer, 4) genetic counseling and testing for women with ovarian cancer and other high-risk families, and 5) salpingectomy after childbearing is complete (at the time of elective pelvic surgeries, at the time of hysterectomy, and as an alternative to tubal ligation). The Society of Gynecologic Oncology has determined that recent scientific breakthroughs warrant a new summary of the progress toward the prevention of ovarian cancer. This review is intended to emphasize the importance of the fallopian tubes as a potential source of high-grade serous cancer in women with and without known genetic mutations in addition to the use of oral contraceptive pills to reduce the risk of ovarian cancer. Cancer 2015;121:2108-20.

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SUMMARY Tumor-reactive T cells become unresponsive in advanced tumors. Here we have characterized a common mechanism of T cell unresponsiveness in cancer driven by the up-regulation of the transcription factor Forkhead box protein P1 (Foxp1), which prevents CD8+ T cells from proliferating and up-regulating Granzyme-B and interferon-γ (IFN-γ) in response to tumor antigens. Accordingly, Foxp1-deficient lymphocytes induced rejection of incurable tumors, and promoted protection against tumor re-challenge. Mechanistically, Foxp1 interacted with the transcription factors Smad2 and Smad3 in pre-activated CD8+ T cells in response to microenvironmental transforming growth factor-β (TGF-β), and was essential for its suppressive activity. Therefore, Smad2 and Smad3-mediated c-Myc repression requires Foxp1 expression in T cells. Furthermore, Foxp1 directly mediated TGF-β-induced c-Jun transcriptional repression, which abrogated T cell activity. Our results unveil a fundamental mechanism of T cell unresponsiveness different from anergy or exhaustion, driven by TGF-β signaling on tumor-associated lymphocytes undergoing Foxp1-dependent transcriptional regulation.