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Because of its relatively indolent clinical course, chronic lymphocytic leukemia (CLL) offers a versatile model for testing novel therapeutic regimens and drug combinations. Nicotinamide is the main NAD +precursor and a direct inhibitor of four classes of enzymes, including the sirtuins. SIRT1, the main member of the sirtuin family, inactivates p53 by deacetylating a critical lysine residue. In this study, we showed that CLL cells express high levels of functional SIRT1, which is inhibited by exogenous nicotinamide. This agent blocks proliferation and promotes apoptosis selectively in leukemic cells that express wild-type (wt) p53. Nicotinamide modulates the p53-dependent genes p21, NOXA, BAX, and Mcl-1, indicating an activation of the p53 pathway and of caspase-3. DNA-damaging chemotherapeutics, such as etoposide, activate a functional loop linking SIRT1 and p53 through the induction of miR-34a. When leukemic cells are simultaneously exposed to nicotinamide and etoposide, we observe a significant increase in miR-34a levels with a concomitant inhibition of SIRT1. Furthermore, p53 acetylation levels are higher than with either agent used alone. Overall, treatment with both nicotinamde and etoposide shows strongly synergistic effects in the induction of apoptosis. We therefore concluded that nicotinamide has the dual property of inhibiting SIRT1 through a noncompetitive enzymatic block (p53 independent) and at the same time through miR-34a induction (p53 dependent). These observations suggested the therapeutic potential of nicotinamide, a novel, safe, and inexpensive drug, to be used in addition to chemotherapy for CLL patients with wt p53. Cancer Res; 71(13); 4473-83. ©2011 AACR. [ABSTRACT FROM AUTHOR]

Circulating cell-free DNA (cfDNA) refers to small fragments of DNA molecules released after programmed cell death and necrosis in several body fluids such as blood, saliva, urine, and cerebrospinal fluid. The discovery of cfDNA has revolutionized the field of non-invasive diagnostics in the oncologic field, in prenatal testing, and in organ transplantation. Despite the potential of cfDNA and the solid results published in the recent literature, several challenges remain, represented by a low abundance, a need for highly sensitive assays, and analytical issues. In this review, the main technical advances in cfDNA analysis are presented and discussed, with a comprehensive examination of the current available methodologies applied in each field. Considering the potential advantages of cfDNA, this biomarker is increasing its consensus among clinicians, as it allows us to monitor patients' conditions in an easy and non-invasive way, offering a more personalized care. Nevertheless, cfDNA analysis is still considered a diagnostic marker to be further validated, and very few centers are implementing its analysis in routine diagnostics. As technical improvements are enhancing the performances of cfDNA analysis, its application will transversally improve patients' quality of life. [ABSTRACT FROM AUTHOR]

Background: One of the effects of oncogenic signaling is metabolic reprogramming of tumor cells to support anabolic growth, opening the way to therapeutic targeting of metabolic pathways.Methods: We studied NAD biosynthesis in BRAF inhibitor (BRAFi)-resistant (BiR) melanoma cell lines. Data in cell lines were confirmed by immunohistochemistry in biopsies from 17 patients with metastatic melanoma (MM) before and after the acquisition of resistance to BRAFi. Therapeutic potential of NAD biosynthesis inhibitors was determined by invitro monitoring cell growth and death and in mouse xenograft models. Mice (n = 6-10 mice/group) were treated with nicotinamide phosphoribosyltranferase inhibitor (NAMPTi), BRAFi, or their combination, and tumor growth and survival were analyzed. All statistical tests were two-sided.Results: BiR cells had higher NAD levels compared with their BRAFi-sensitive counterparts (P < .001 and P = .001 for M14 and A375, respectively) and with normal melanocytes (P < .001), achieved through transcriptional upregulation of the enzyme NAMPT, which became the master regulator of NAD synthesis. Conversely, treatment with BRAFi or MEK inhibitors decreased NAMPT expression and cellular NAD levels. Robust NAMPT upregulation was documented in tissue biopsies from MM patients after development of resistance to BRAFi (P < .001). Treatment of melanoma cells with NAMPTi depleted NAD and ATP, depolarized mitochondrial membrane, and led to reactive oxygen species production, blocking cells in the G2/M phase and inducing apoptosis. Treatment of BiR xenografts with NAMPTi improved mouse survival (median survival of vehicle-treated mice was 52 days vs 100 days for NAMPTi-treated ones in M14/BiR, while in A375/BiR median survival of vehicle-treated mice was 23.5 days vs 43 days for NAMPTi-treated ones, P < .001).Conclusions: BiR melanoma cells overexpress NAMPT, which acts as a connecting element between BRAF oncogenic signaling and metabolism, becoming an actionable target for this subset of MM patients. [ABSTRACT FROM AUTHOR]