Laura Prieto-García

Subcellular targets of cisplatin cytotoxicity: an integrated view.

Cisplatin is a chemotherapeutic drug widely used against a variety of cancers. Its clinical utility is severely limited by its toxicity, which mainly affects, but is not limited to, the inner ear and renal tubules. Cisplatin toxicity is determined by target tissue and cell accumulation, subcellular handling and trafficking through diverse subcellular structures, and interaction with macromolecules. Cisplatin accumulates and stresses different organelles from which delay signaling is activated, including mitochondria, lysosomes, the endoplasmic reticulum, the nucleus, the cell membrane and cytoskeleton, and can also be found in the cytosol. This article critically summarizes the available information in order to establish the connection among its known subcellular effects in a hierarchical and integrative framework. Cisplatin causes different types of cell death in a concentration-dependent manner. Knowledge of the events and signaling leading to the different phenotypes is also intertwined within the model, within the scope of the potential utility of this information in the improvement of the pharmacotoxicological profile of this drug. Perspectives for the key aspects that need to be addressed by future investigation are also outlined.

Urinary proteomics in renal pathophysiology: Impact of proteinuria

Urinary differential proteomics is used to study renal pathophysiological mechanisms, find novel markers of biological processes and renal diseases, and stratify patients according to proteomic profiles. The proteomic procedure determines the pathophysiological meaning and clinical relevance of results. Urine samples for differential proteomic studies are usually normalized by protein content, regardless of its pathophysiological characteristics. In the field of nephrology, this approach translates into the comparison of a different fraction of the total daily urine output between proteinuric and nonproteinuric samples. Accordingly, alterations in the level of specific proteins found by this method reflect the relative presence of individual proteins in the urine; but they do not necessarily show alterations in their daily excretion, which is a key parameter for the understanding of the pathophysiological meaning of urinary components. For renal pathophysiology studies and clinical biomarker identification or determination, an alternative proteomic concept providing complementary information is based on sample normalization by daily urine output, which directly informs on changes in the daily excretion of individual proteins. This is clinically important because daily excretion (rather than absolute or relative concentration) is the only self‐normalized way to evaluate the real meaning of urinary parameters, which is also independent of urine concentration.

Increased Klk9 Urinary Excretion Is Associated to Hypertension-Induced Cardiovascular Damage and Renal Alterations.

AbstractEarly detection of hypertensive end-organ damage and secondary diseases are key determinants of cardiovascular prognosis in patients suffering from arterial hypertension. Presently, there are no biomarkers for the detection of hypertensive target organ damage, most outstandingly including blood vessels, the heart, and the kidneys.We aimed to validate the usefulness of the urinary excretion of the serine protease kallikrein-related peptidase 9 (KLK9) as a biomarker of hypertension-induced target organ damage.Urinary, plasma, and renal tissue levels of KLK9 were measured by the Western blot in different rat models of hypertension, including angiotensin-II infusion, DOCA-salt, L-NAME administration, and spontaneous hypertension. Urinary levels were associated to cardiovascular and renal injury, assessed by histopathology. The origin of urinary KLK9 was investigated through in situ renal perfusion experiments.The urinary excretion of KLK9 is increased in different experimental models of hypertension in rats. The ACE inhibitor trandolapril significantly reduced arterial pressure and the urinary level of KLK9. Hypertension did not increase kidney, heart, liver, lung, or plasma KLK9 levels. Hypertension-induced increased urinary excretion of KLK9 results from specific alterations in its tubular reabsorption, even in the absence of overt nephropathy. KLK9 urinary excretion strongly correlates with cardiac hypertrophy and aortic wall thickening.KLK9 appears in the urine in the presence of hypertension as a result of subtle renal handling alterations. Urinary KLK9 might be potentially used as an indicator of hypertensive cardiac and vascular damage.

N-acetylcysteine transforms necrosis into apoptosis and affords tailored protection from cisplatin cytotoxicity

ABSTRACT Nephrotoxicity is the main limitation to the dosage and anticancer efficacy of cisplatin. Cisplatin produces tubular epithelial cell apoptosis and necrosis depending on the concentration of the drug. Protection from cisplatin nephrotoxicity must therefore tackle both cell death modes. For its ability to reduce cisplatin reactivity, in addition to its antioxidant effect, we tested and found that N‐acetylcysteine (NAC) was most effective at inhibiting cisplatin cytotoxicity. NAC has no significant effect on cell death induced by either cycloheximide or Fas activation, indicating a rather selective action. Pt‐DNA‐binding experiments suggest that the differential effectiveness of NAC is due to its capacity to quench cisplatin reactivity inside the cell. NAC abolishes cisplatin‐induced apoptosis, and transforms the necrosis induced by high concentrations of cisplatin into apoptosis. In fact, NAC allows the anti‐apoptotic molecule Bcl‐2 to reduce the cell death caused by pro‐necrotic concentrations of cisplatin, to a significantly greater extent than in the absence of NAC. In rats, a dosage of NAC that significantly ameliorates cisplatin nephrotoxicity, has little effect on gentamicin nephrotoxicity. These characteristics provide NAC with a rationale as a potential nephroprotectant specifically tailored to and especially effective for therapeutic courses with platinated antineoplastics, which prompts to deepening into further preclinical knowledge, and to initiate clinical studies with NAC and mixed therapies composed of NAC and antiapoptotic drugs. HIGHLIGHTSAntioxidant‐independent effects N‐acetylcysteine afford tubular cytoprotection.N‐acetylcysteine binds intracellular cisplatin and reduces its reactivity.N‐acetylcysteine transforms cisplatin‐induced necrosis into apoptosis.N‐acetylcysteine is a potential nephroprotectant of cisplatin nephrotoxicity.