No / Most cancer cells use aerobic glycolysis to fuel their growth. The enzyme lactate dehydrogenase-A (LDH-A) is key to cancer’s glycolytic phenotype, catalysing the regeneration of nicotinamide adenine dinucleotide (NAD+) from reduced nicotinamide adenine dinucleotide (NADH) necessary to sustain glycolysis. As such, LDH-A is a promising target for anticancer therapy. Here we ask if the tumour suppressor p53, a major regulator of cellular metabolism, influences the response of cancer cells to LDH-A suppression. LDH-A knockdown by RNA interference (RNAi) induced cancer cell death in p53 wild-type, mutant and p53-null human cancer cell lines, indicating that endogenous LDH-A promotes cancer cell survival irrespective of cancer cell p53 status. Unexpectedly, however, we uncovered a novel role for p53 in the regulation of cancer cell NAD+ and its reduced form NADH. Thus, LDH-A silencing by RNAi, or its inhibition using a small-molecule inhibitor, resulted in a p53-dependent increase in the cancer cell ratio of NADH:NAD+. This effect was specific for p53+/+ cancer cells and correlated with (i) reduced activity of NAD+-dependent deacetylase sirtuin 1 (SIRT1) and (ii) an increase in acetylated p53, a known target of SIRT1 deacetylation activity. In addition, activation of the redox-sensitive anticancer drug EO9 was enhanced selectively in p53+/+ cancer cells, attributable to increased activity of NAD(P)H-dependent oxidoreductase NQO1 (NAD(P)H quinone oxidoreductase 1). Suppressing LDH-A increased EO9-induced DNA damage in p53+/+ cancer cells, but importantly had no additive effect in non-cancer cells. Our results identify a unique strategy by which the NADH/NAD+ cellular redox status can be modulated in a cancer-specific, p53-dependent manner and we show that this can impact upon the activity of important NAD(H)-dependent enzymes. To summarise, this work indicates two distinct mechanisms by which suppressing LDH-A could potentially be used to kill cancer cells selectively, (i) through induction of apoptosis, irrespective of cancer cell p53 status and (ii) as a part of a combinatorial approach with redox-sensitive anticancer drugs via a novel p53/NAD(H)-dependent mechanism.

This study describes a novel thermoresponsive dendritic polyethylene glycol-poly(D, L-lactide) (PEG-PDLLA) core-shell nanoparticle with potential for drug delivery and controlled release. A series of dendritic PEG-PDLLA nanoparticles were synthesized through conjugation of PEG to Starburst™ polyamidoamine (PAMAM) dendrimer G3.0 and subsequent ring-opening polymerization of DLLA, in which PEG chain length (i.e., MW=1500, 6000 or 12000 Dalton) was varied; however, the feeding molar ratio of DLLA monomers to the overall PEG repeat units on the dendrimer surface was kept at 1:1. Linear PEG-PDLLA copolymers were also syntheiszed under the same condition and used as control. According to our results, dendritic PEG-PDLLA in aqueous phase could self-assemble into spherical aggregates and the size of spherical aggregates increased with PEG chain length increase. Further, spherical aggregates made of dendritic PEG-PDLLA exhibited magnified temperature-dependence in terms of solubility change and dimension expansion as compared to linear PEG-PDLLA. The most significant size expansion was observed in particles made of dendritic PEG (12000)-PDLLA, which was twice as much as that of particles made of linear PEG (12000)-PDLLA. Water insoluble antitumor drug camptothecin (CPT) was used as a model drug for encapsulation and release studies. Spherical aggregates encapsulated more CPT when dendritic PEG-PDLLA had longer PEG-PDLLA chain and/or when temperature was elevated to body temperature. This study demonstrated that nanoscale clustering PEG-PDLLA through dendrimers magnified the thermo-sensitivity of PEG-PDLLA. Successful development of such a new particulate system made of dendritic PEG-PDLLA with an expandable dimension in response to temperature change generated a new direction for designing stimuli-responsive materials.

La bêta-lapachone (b-lap) est une substance active présentant des activités trypanocides, anti-infectieuses et anticancéreuses, avec une sélectivité thérapeutique. Cependant, en raison de sa faible hydrosolubilité et de sa toxicité, b-lap n'est pas encore appliquée en clinique. Nous avons étudié son encapsulation dans des vésicules phospholipidiques, complexée ou non par des cyclodextrines. Nous avons d'abord analysé l'interaction de b-lap avec des excipients lipidiques par des mesures de pression de surface, DSC et SAXS. Elles ont montré que blap est insérée dans les bicouches lipidiques, proche des têtes polaires avec une solubilité maximale d'environ 3,5 mol%. Les résultats expérimentaux ont été confirmés par des simulations de dynamique moléculaire. Le taux d'encapsulation (ER%) de b-lap dans les liposomes s’est avéré en accord avec sa solubilité maximale dans les lipides. Des complexes b-lap:cyclodextrines ont été formés et incorporés dans le coeur aqueux de liposomes déjà chargés en b-lap. Des ER% plus élevés ont été obtenus, mais avec une efficacité d'encapsulation plus faible. Des tests in vitro sur des lignées cellulaires épithéliales et tumorales de prostate ont démontré la cytotoxicité élevée de b-lap, sans différence toutefois entre b-lap libre et formulée, ni entre les cellules normales et les cellules cancéreuses. / Beta-lapachone (b-lap) is a potential drug with trypanocidal, anti-infectious and anticancer activities with reported selectivity of effects. However, due to its poor water solubility and toxicity, b-lap is not yet applied in therapeutics. We have studied the encapsulation of b-lap in conventional phospholipid vesicles and in-cyclodextrin-in-liposomes. We first analyzed the interaction of b-lap with lipid excipients by surface pressure measurements, DSC and SAXS. They showed that b-lap inserts in lipid bilayers close to polar head groups with a maximum solubility of about 3.5 mol%. The experimental results were supported by molecular dynamics simulations. Encapsulation rates (ER%) of b-lap in liposomes were consistent with b-lap maximal solubility in lipids. B-lap:cyclodextrin complexes were formed and entrapped in the aqueous core of blap-loaded liposomes. Higher ER% were obtained, but with lower encapsulation efficiency. In vitro tests on prostate epithelial and tumor cell lines demonstrated the high cytotoxicity of b-lap, however, without difference between formulated and free b-lap, nor between normal and cancer cells.

PMEG [9-(2-phosphonomethoxyethyl)guanine] and PMEDAP [9-phosphonomethoxy- ethyl)-2,6-diaminopurine] are acyclic nucleoside phosphonates possessing cytotoxic properties. Antiproliferative effect of PMEG was demonstrated in various tumor cell lines in vitro. PMEG also represents an active component of some experimental prodrugs with enhanced selectivity and efficacy (such as GS-9219). PMEDAP seems to have weaker effect in vitro compared to PMEG, however it exhibited pronounced antitumor effect in SD-rats with spontaneous lymphoma. Therefore it was included in the present study as well. The aim of this study was to describe the interactions of PMEG and PMEDAP with p38 MAP kinase signaling and its relationship to the apoptosis. We investigated the influence of these compounds on the expression of four genes encoding p38 MAPK isoforms and whether this change is translated into the protein. It was found that PMEG up-regulates p38β and γ mRNA in CCRF-CEM cells and p38 β and δ in HL-60 cells. The effect of PMEDAP was less pronounced than that of PMEG. However, total p38 protein level remained unaffected by PMEG and PMEDAP. Activation of p38 MAPK cascade was also measured in the cells exposed to these agents using phospho-specific antibodies. We found that neither PMEG nor PMEDAP activated p38 kinase...

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