Knockdown of iPLA2γ enhances cisplatin-induced apoptosis by increasing ROS-dependent peroxidation of mitochondrial phospholipids in bladder cancer cells

Cisplatin (CDDP) is a platinum-based drug with anti-cancer activity and is widely used as a standard therapy for bladder cancer. It is well known that CDDP causes cell death by increasing the generation of reactive oxygen species (ROS) and lipid peroxidation, but the mechanism of its anti-cancer effects has not been fully elucidated. There are still some problems such as chemoresistance in CDDP therapy. In the present study, we found the expression of Ca2+-independent phospholipase A2γ (iPLA2γ), which has been reported to regulate cellular redox homeostasis by inhibiting lipid peroxide accumulation, in human bladder cancer tissues. Thus, we investigated the effect of iPLA2γ knockdown on CDDP-induced bladder cancer cell death. As a result, we found that iPLA2γ knockdown significantly enhanced CDDP-induced apoptosis, intracellular and mitochondrial ROS production, cytochrome c release and caspase activation in bladder cancer cells. Moreover, mitochondrial membrane potential was decreased and peroxidation of mitochondrial phospholipids was increased by iPLA2γ knockdown. It was also shown that co-treatment of bromoenol lactone, an iPLA2 inhibitor, increased CDDP-induced apoptosis. These results indicated that iPLA2γ plays an important role in protecting bladder cancer cells from CDDP-induced apoptosis, and that iPLA2γ inhibitors might represent a novel strategy in CDDP-based multi-drug therapy.

Identification of Diagnostic Metabolic Signatures in Thyroid Tumors Using Mass Spectrometry Imaging

"Gray zone" thyroid follicular tumors are difficult to diagnose, especially when distinguishing between benign follicular thyroid adenoma (FTA) and malignant carcinoma (FTC). Thus, proper classification of thyroid follicular diseases may improve clinical prognosis. In this study, the diagnostic performance of metabolite enzymes was evaluated using imaging mass spectrometry to distinguish FTA from FTC and determine the association between metabolite enzyme expression with thyroid follicular borderline tumor diagnosis. Air flow-assisted desorption electrospray ionization mass spectrometry imaging (AFAIDESI-MSI) was used to build a classification model for thyroid follicular tumor characteristics among 24 samples. We analyzed metabolic enzyme marker expression in an independent validation set of 133 cases and further evaluated the potential biological behavior of 19 thyroid borderline lesions. Phospholipids and fatty acids (FAs) were more abundant in FTA than FTC (p < 0.001). The metabolic enzyme panel, which included FA synthase and Ca2+-independent PLA2, was further validated in follicular thyroid tumors. The marker combination showed optimal performance in the validation group (area under the ROC, sensitivity, and specificity: 73.6%, 82.1%, and 60.6%, respectively). The findings indicate that AFAIDESI-MSI, in combination with low metabolic enzyme expression, could play a role in the diagnosis of thyroid follicular borderline tumors for strict follow-up.

Phospholipase A2 superfamily in cancer

Phospholipase A2 enzymes (PLA₂s) comprise a superfamily that is generally divided into six subfamilies known as cytosolic PLA₂s (cPLA₂s), calcium-independent PLA₂s (iPLA₂s), secreted PLA₂s (sPLA₂s), lysosomal PLA₂s, platelet-activating factor (PAF) acetylhydrolases, and adipose specific PLA₂s. Each subfamily consists of several isozymes that possess PLA₂ activity. The first three PLA₂ subfamilies play important roles in inflammation-related diseases and cancer. In this review, the roles of well-studied enzymes sPLA₂-IIA, cPLA₂α and iPLA₂β in carcinogenesis and cancer development were discussed. sPLA₂-IIA seems to play conflicting roles and can act as a tumor suppressor or a tumor promoter according to the cancer type, but cPLA₂α and iPLA₂β play protumorigenic role in most cancers. The mechanisms of PLA₂-mediated signal transduction and crosstalk between cancer cells and endothelial cells in the tumor microenvironment are described. Moreover, the mechanisms by which PLA₂s mediate lipid reprogramming and glycerophospholipid remodeling in cancer cells are illustrated. PLA₂s as the upstream regulators of the arachidonic acid cascade are generally high expressed and activated in various cancers. Therefore, they can be considered as potential pharmacological targets and biomarkers in cancer. The detailed information summarized in this review may aid in understanding the roles of PLA₂s in cancer, and provide new clues for the development of novel agents and strategies for tumor prevention and treatment.

Similarities in Blood Mononuclear Cell Membrane Phospholipid Profiles During Malignancy

Phospholipids (PLs), key elements of cellular membranes, are regulated reciprocally with membrane proteins and can act as sensors for alterations in physiological or pathological states of cells including initiation and development of cancer. On the other hand, peripheral blood mononuclear cells (MNCs) play an important role in antitumor immune response by reacting to cancerous modifications in distant organs. In the current study, we tested the hypothesis that tumor initiation and development are reflected in the alteration pattern of the MNC PL component. We analyzed MNC membrane PL fractions in samples from healthy individuals and from patients with diverse types of cancers to reveal possible alterations induced by malignancy. Compared to healthy controls, the cancer samples demonstrated shifts in several membrane PL profiles. In particular, when analyzing cancer data pooled together, there were significantly higher levels in lysophosphatidylcholine, phosphatidylcholine, and phosphatidylethanolamine fractions, and significantly lower quantities in phosphatidylinositol, phosphatidylserine, and phosphatidic acid fractions in cancer samples compared to controls. The levels of sphingomyelins and diphosphatidylglycerols were relatively unaffected. Most of the differences in PLs were sustained during the analysis of individual cancers such as breast cancer and chronic lymphocytic leukemia. Our findings suggest the presence of a common pattern of changes in MNC PLs during malignancy.

Synthetic and natural inhibitors of phospholipases A2: their importance for understanding and treatment of neurological disorders

Phospholipases A2 (PLA2) are a diverse group of enzymes that hydrolyze membrane phospholipids into arachidonic acid and lysophospholipids. Arachidonic acid is metabolized to eicosanoids (prostaglandins, leukotrienes, thromboxanes), and lysophospholipids are converted to platelet-activating factors. These lipid mediators play critical roles in the initiation, maintenance, and modulation of neuroinflammation and oxidative stress. Neurological disorders including excitotoxicity; traumatic nerve and brain injury; cerebral ischemia; Alzheimer's disease; Parkinson's disease; multiple sclerosis; experimental allergic encephalitis; pain; depression; bipolar disorder; schizophrenia; and autism are characterized by oxidative stress, inflammatory reactions, alterations in phospholipid metabolism, accumulation of lipid peroxides, and increased activities of brain phospholipase A2 isoforms. Several old and new synthetic inhibitors of PLA2, including fatty acid trifluoromethyl ketones; methyl arachidonyl fluorophosphonate; bromoenol lactone; indole-based inhibitors; pyrrolidine-based inhibitors; amide inhibitors, 2-oxoamides; 1,3-disubstituted propan-2-ones and polyfluoroalkyl ketones as well as phytochemical based PLA2 inhibitors including curcumin, Ginkgo biloba and Centella asiatica extracts have been discovered and used for the treatment of neurological disorders in cell culture and animal model systems. The purpose of this review is to summarize information on selective and potent synthetic inhibitors of PLA2 as well as several PLA2 inhibitors from plants, for treatment of oxidative stress and neuroinflammation associated with the pathogenesis of neurological disorders.

The role of phosphatidylcholine and choline metabolites to cell proliferation and survival

The reorganization of metabolic pathways in cancer facilitates the flux of carbon and reducing equivalents into anabolic pathways at the expense of oxidative phosphorylation. This provides rapidly dividing cells with the necessary precursors for membrane, protein and nucleic acid synthesis. A fundamental metabolic perturbation in cancer is the enhanced synthesis of fatty acids by channeling glucose and/or glutamine into cytosolic acetyl-CoA and upregulation of key biosynthetic genes. This lipogenic phenotype also extends to the production of complex lipids involved in membrane synthesis and lipid-based signaling. Cancer cells display sensitivity to ablation of fatty acid synthesis possibly as a result of diminished capacity to synthesize complex lipids involved in signaling or growth pathways. Evidence has accrued that phosphatidylcholine, the major phospholipid component of eukaryotic membranes, as well as choline metabolites derived from its synthesis and catabolism, contribute to both proliferative growth and programmed cell death. This review will detail our current understanding of how coordinated changes in substrate availability, gene expression and enzyme activity lead to altered phosphatidylcholine synthesis in cancer, and how these changes contribute directly or indirectly to malignant growth. Conversely, apoptosis targets key steps in phosphatidylcholine synthesis and degradation that are linked to disruption of cell cycle regulation, reinforcing the central role that phosphatidylcholine and its metabolites in determining cell fate.

Fluoroketone inhibition of Ca(2+)-independent phospholipase A2 through binding pocket association defined by hydrogen/deuterium exchange and molecular dynamics

The mechanism of inhibition of group VIA Ca²⁺-independent phospholipase A₂ (iPLA₂) by fluoroketone (FK) ligands is examined by a combination of deuterium exchange mass spectrometry (DXMS) and molecular dynamics (MD). Models for iPLA₂ were built by homology with the known structure of patatin and equilibrated by extensive MD simulations. Empty pockets were identified during the simulations and studied for their ability to accommodate FK inhibitors. Ligand docking techniques showed that the potent inhibitor 1,1,1,3-tetrafluoro-7-phenylheptan-2-one (PHFK) forms favorable interactions inside an active-site pocket, where it blocks the entrance of phospholipid substrates. The polar fluoroketone headgroup is stabilized by hydrogen bonds with residues Gly486, Gly487, and Ser519. The nonpolar aliphatic chain and aromatic group are stabilized by hydrophobic contacts with Met544, Val548, Phe549, Leu560, and Ala640. The binding mode is supported by DXMS experiments showing an important decrease of deuteration in the contact regions in the presence of the inhibitor. The discovery of the precise binding mode of FK ligands to the iPLA₂ should greatly improve our ability to design new inhibitors with higher potency and selectivity.

Complement-mediated activation of calcium-independent phospholipase A2γ: role of protein kinases and phosphorylation

In experimental membranous nephropathy, complement C5b-9-induces glomerular epithelial cell (GEC) injury and proteinuria. The effects of C5b-9 are mediated via signaling pathways, including calcium-independent phospholipase A(2)γ (iPLA(2)γ), and mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38. The iPLA(2)γ pathway is cytoprotective. This study addresses the mechanisms of iPLA(2)γ activation. iPLA(2)γ activity was monitored by quantifying prostaglandin E(2) (PGE(2)) production. In GECs, iPLA(2)γ localized at the endoplasmic reticulum and mitochondria. Complement-mediated production of PGE(2) was amplified in GECs that overexpress iPLA(2)γ, compared with control cells, and was blocked by the iPLA(2)γ inhibitor bromoenol lactone in both iPLA(2)γ-overexpressing and control GECs. In GECs that overexpress iPLA(2)γ, complement-mediated PGE(2) production was reduced by inhibitors of MAP/ERK kinase 1 (MEK1) and p38 but not JNK. In COS-1 cells that overexpress iPLA(2)γ and cyclooxygenase-1, PGE(2) production was induced by co-expression of constitutively active MEK1 or MAPK-interacting kinase 1 (MNK1) as well as by stimulation with epidermal growth factor (EGF) + ionomycin. Complement- and EGF + ionomycin-stimulated iPLA(2)γ activity was attenuated by the S511A/S515A double mutation. Moreover, complement and EGF + ionomycin enhanced phosphorylation of Ser-511. Thus, complement-mediated activation of iPLA(2)γ is mediated via ERK and p38 pathways, and phosphorylation of Ser-511 and/or Ser-515 plays a key role in the catalytic activity and signaling of iPLA(2)γ. Defining the mechanisms by which complement activates iPLA(2)γ provides opportunities for development of novel therapeutic approaches to GEC injury and proteinuria.

Haloenol pyranones and morpholinones as antineoplastic agents of prostate cancer

Haloenol pyran-2-ones and morpholin-2-ones were synthesized and evaluated as inhibitors of cell growth in two different prostate human cancer cell lines (PC-3 and LNCaP). Analogs derived from L- and D-phenylglycine were found to be the most effective antagonists of LNCaP and PC-3 cell growth. Additional studies reveal that the inhibitors induced G2/M arrest and the (S)-enantiomer of the phenylglycine-based derivatives was a more potent inhibitor of cytosolic iPLA(2)β.

Composition of molecular cardiolipin species correlates with proliferation of lymphocytes

The mitochondrial phospholipid cardiolipin (CL) is required for oxidative phosphorylation. Oxidation of CL results in the disruption of CL-cytochrome c binding and the induction of apoptosis. Large variations in the acyl-chain residues of CL have been reported, but evidence as to whether these variants exert distinct biological effects has been limited. We have studied the acyl-chain composition of CL in lymphocytes, and found marked differences between highly and slowly proliferating cells. In fast growing cells, we detected a decreased number of double bonds, and a higher amount of C16 acyl-chain residues in CL, compared with slower growing cells. However, fewer C18 acyl-chain residues were found in CL from fast growing cells compared with slower proliferating cells. Our results suggest a functional link between acyl-chain composition of CL and cell proliferation.

Enhanced antitumor activity of low-dose continuous administration schedules of topotecan in prostate cancer

PURPOSE

The objective of this study was to determine the antitumor effects of alternate dosing schedules of topotecan in prostate cancer.

RESULTS

A concentration-dependent increase in cytotoxicity was observed in PC-3 and LNCaP cells after topotecan treatment using conventional and metronomic protocols. A significant increase in potency (2.4-18 fold, after 72 hr) was observed following metronomic dosing compared to conventional dosing administration in both cell lines. Metronomic dosing also increased the percentage of PC-3 cells in the G2/M, compared to control, but did not alter LNCaP cell cycle distribution. Metronomic dosing increased p21 protein expression in LNCaP and PC-3 cells compared to conventional dosing. The observed in vitro activity was confirmed using an in vivo model of human prostate cancer. Metronomic dosing and continuous infusion decreased tumor volume significantly (p < 0.05) compared to control and conventional topotecan treatment, but had no effect on tumor vascular staining.

METHODS

The cytotoxicity of topotecan after conventional or metronomic dosing was determined by examining cellular morphology, mitochondrial enzymatic activity (MTT), total cellular protein (SRB), annexin V and propidium iodine (PI) staining, cell cycle and western blot analysis in human prostate cancer cell lines (PC-3 and LNCaP) and the effects metronomic or continuous infusion on tumor growth in an in vivo tumor xenograft model.

CONCLUSIONS

These data support the hypothesis that low-dose continuous administration of topotecan increases potency compared to conventional dosing in prostate cancer. These data also suggest the novel finding that the enhanced antitumor activity of topotecan following low-dose exposure correlates to alterations in cell cycle and increased p21 expression.

Tumor cell group via phospholipase A₂ is involved in prostate cancer development

BACKGROUND

Prostate cancer (PCa) is one of the most common malignancies among men in the United States. Further understanding of the molecular mechanisms underlying PCa tumorigenic development is critical for advancing treatment strategies for PCa. The role of Group VIA phospholipase A₂β (iPLA₂β) in cancers has recently emerged. However, the biological functions of iPLA₂β in PCa development have been minimally investigated and only in vitro studies have been reported.

METHODS

We tested the role of iPLA₂β in host cells using an iPLA₂β deficient mouse model and the role of iPLA₂β in tumor cells by comparing the proliferation, migration, and invasion in vitro and tumorigenesis in vivo.

CONCLUSIONS

iPLA₂β deficiency did not affect tumor development in C57BL/6 mice injected with syngeneic PCa cell line TRAMP-C1P3 in any of three models (subcutaneous, orthotopic, or intratibia injection) tested, suggesting that host cell iPLA₂β is not required for PCa tumorigenesis and metastasis. In contrast, when iPLA₂β was down-regulated in TRAMP-C1P3 cells, cell proliferation was reduced in vitro and tumor growth was suppressed in vivo compared to control cells. In particular, iPLA₂β was required for lysophosphatidic acid (LPA)-induced migration and invasion in TRAMP-C1P3 cells. We compared human and mouse PCa cells and showed that they shared high similarities in LPA-stimulated effects and signaling pathways. LPA stimulated cell migration and/or invasion via a PI3K-dependent pathway. Together, our results suggest that the tumor cell iPLA₂β-LPA axis may represent a novel target for PCa.

Platelet-activating factor and metastasis: calcium-independent phospholipase A2β deficiency protects against breast cancer metastasis to the lung

We determined the contribution of calcium-independent phospholipase A(2)β (iPLA(2)β) to lung metastasis development following breast cancer injection into wild-type (WT) and iPLA(2)β-knockout (iPLA(2)β-KO) mice. WT and iPLA(2)β-KO mice were injected in the mammary pad with 200,000 E0771 breast cancer cells. There was no difference in primary tumor size between WT and iPLA(2)β-KO mice at 27 days postinjection. However, we observed an 11-fold greater number of breast cancer cells in the lungs of WT mice compared with iPLA(2)β-KO animals (P < 0.05). Isolated WT lung endothelial cells demonstrated a significant increase in platelet-activating factor (PAF) production when stimulated with thrombin [1 IU/ml, 10 min, 4,330 ± 555 vs. 15,227 ± 1,043 disintegrations per minute (dpm), P < 0.01] or TNF-α (10 ng/ml, 2 h, 16,532 ± 538 dpm, P < 0.01). Adherence of E0771 cells to WT endothelial cells was increased by thrombin (4.8 ± 0.3% vs. 70.9 ± 6.3, P < 0.01) or TNF-α (60.5 ± 4.3, P < 0.01). These responses were blocked by pretreatment with the iPLA(2)β-selective inhibitor (S)-bromoenol lactone and absent in lung endothelial cells from iPLA(2)β-KO mice. These data indicate that endothelial cell iPLA(2)β is responsible for PAF production and adherence of E0771 cells and may play a role in cancer cell migration to distal locations.

Inhibition of calcium-independent phospholipase A2 activates p38 MAPK signaling pathways during cytostasis in prostate cancer cells

The p38 mitogen-activated protein kinase (MAPK) signaling pathways activated during cytostasis induced by Ca(2+)-independent phospholipase A2 (iPLA2) inhibition in prostate cancer cells were investigated. iPLA2 inhibition using siRNA, or the selective inhibitor bromoenol lactone (BEL) and it's enantiomers, decreased growth in LNCaP (p53 positive) and PC-3 (p53 negative) human prostate cancer cells. Decreased cell growth correlated to time- and concentration-dependent activation of the mitogen-activated protein kinase p38 in both cell lines. Inhibition of cytosolic iPLA(2)beta using S-BEL, induced significantly higher levels of P-p53, p53, p21 and P-p38 expression than inhibition of microsomal iPLA2 gamma using R-BEL. Inhibition of p38 using SB202190 or SB203580 inhibited BEL-induced increases in P-p53 (ser15), p53 and p21, and altered the number of cells in G1 in LNCaP cells, and S-phase in PC-3 cells. BEL treatment also induced reactive species in PC-3 and LNCaP cells, which was partially reversed by pretreatment with N-acetyl-cysteine (NAC). NAC subsequently inhibited BEL-induced activation of p38 and p53 in LNCaP cells. In addition, treatment of cells with NAC partially reversed the effect of BEL on cell growth and preserved cell morphology. Collectively, these data demonstrate the novel findings that iPLA2 inhibition activates p38 by inducing reactive species, and further suggest that this signaling kinase is involved in p53 activation, cell cycle arrest and cytostasis.

Cellular and molecular mechanisms of bromate-induced cytotoxicity in human and rat kidney cells

The mechanisms of bromate (BrO(3)(-))-induced toxicity in Normal Rat Kidney (NRK) and human embryonic kidney 293 (HEK293) cells were investigated. BrO(3)(-) (added as KBrO(3)) induced concentration-dependent decreases in 3-(4, dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) staining after 48 h. BrO(3)(-)-induced necrosis based on tandem increases in annexin V and PI staining. Cell cycle analysis demonstrated that BrO(3)(-) also induced G2/M arrest and nuclear fragmentation, prior to alterations in MTT staining or annexin V and PI staining. Immunoblot analysis demonstrated that the G2/M arrest correlated to induction of phosphorylated (p)-p53, p21, cyclin B1 and p-cdc2. Further, BrO(3)(-) induced time-dependent increases in the activity of the mitogen activated protein kinases p38 and ERK1/2. Treatment of cells with the p38 inhibitor SB202190, but not the ERK1/2 inhibitor PD98059, partially reversed BrO(3)(-)-induced G2/M arrest and decreased BrO(3)(-)-induced p-p53, p21 and cyclin B1 expression. In addition, BrO(3)(-) treatment induced reactive oxygen species (ROS) based on increases in CM-H(2)DCFDA fluorescence. The antioxidant ascorbic acid inhibited BrO(3)(-)-induced p38 activation, G2/M arrest, p-p53, p21 and cyclin B1 expression; however, ascorbic acid had no effect on BrO(3)(-)-induced formation of 8-OHdG, a marker of DNA oxidative damage, whose increases preceded cell death by 24h. These data suggest that ROS mediated MAPK activation is involved in the molecular mechanisms of BrO(3)(-)-induced cell cycle arrest, which occurs independently of 8-OH-dG production. The similar mode of action in both NRK and HEK293 cells suggests that the mechanisms of BrO(3)(-)-induced renal cell death are model-independent.

Genome-wide association study identifies variants at 9p21 and 22q13 associated with development of cutaneous nevi

A high melanocytic nevi count is the strongest known risk factor for cutaneous melanoma. We conducted a genome-wide association study for nevus count using 297,108 SNPs in 1,524 twins, with validation in an independent cohort of 4,107 individuals. We identified strongly associated variants in MTAP, a gene adjacent to the familial melanoma susceptibility locus CDKN2A on 9p21 (rs4636294, combined P = 3.4 x 10(-15)), as well as in PLA2G6 on 22q13.1 (rs2284063, combined P = 3.4 x 10(-8)). In addition, variants in these two loci showed association with melanoma risk in 3,131 melanoma cases from two independent studies, including rs10757257 at 9p21, combined P = 3.4 x 10(-8), OR = 1.23 (95% CI = 1.15-1.30) and rs132985 at 22q13.1, combined P = 2.6 x 10(-7), OR = 1.23 (95% CI = 1.15-1.30). This provides the first report of common variants associated to nevus number and demonstrates association of these variants with melanoma susceptibility.

Pharmacological targeting of the integrated protein kinase B, phosphatase and tensin homolog deleted on chromosome 10, and transforming growth factor-beta pathways in prostate cancer

Prostate cancer is a highly heterogenous disease in which a patient-tailored care program is much desired. Central to this goal is the development of novel targeted pharmacological interventions. To develop these treatment strategies, an understanding of the integration of cellular pathways involved in both tumorigenesis and tumor suppression is crucial. Of further interest are the events elicited by drug treatments that exploit the underlying molecular pathology in cancer. This review briefly describes the evidence that suggests integration of three established pathways: the tumorigenic phosphoinositide 3-kinase/protein kinase B (AKT) pathway, the tumor suppressive phosphatase and tensin homolog deleted on chromosome 10 pathway, and the tumor suppressive transforming growth factor-beta pathway. More importantly, we discuss novel pharmaceutical agents that target key points of integration in these three pathways. These new therapeutic strategies include the use of agents that target iron to inhibit proliferation via multiple mechanisms and suppression of AKT by cytosolic phospholipase A(2)-alpha inhibitors.

Role of Ca2+-independent phospholipase A2 in cell growth and signaling

Phospholipase A(2) (PLA(2)) are esterases that cleave glycerophospholipids to release fatty acids and lysophospholipids. Several studies demonstrate that PLA(2) regulate growth and signaling in several cell types. However, few of these studies have focused on Ca2+-independent phospholipase A(2) (iPLA(2) or Group VI PLA(2)). This class of PLA(2) was originally suggested to mediate phospholipid remodeling in several cell types including macrophages. As such, it was labeled as a housekeeping protein and thought not to play as significant of roles in cell growth as its older counterparts cytosolic PLA(2) (cPLA(2) or Group IV PLA(2)) and secretory PLA(2) (sPLA(2) or Groups I-III, V and IX-XIV PLA(2)). However, several recent studies demonstrate that iPLA(2) mediate cell growth, and do so by participating in signal transduction pathways that include epidermal growth factor receptors (EGFR), mitogen activated protein kinases (MAPK), mdm2, and even the tumor suppressor protein p53 and the cell cycle regulator p21. The exact mechanism by which iPLA(2) mediates these pathways are not known, but likely involve the generation of lipid signals such as arachidonic acid, lysophosphatidic acid (LPA) and lysophosphocholines (LPC). This review discusses the role of iPLA(2) in cell growth with special emphasis placed on their role in cell signaling. The putative lipid signals involved are also discussed.

Regulation and pathological role of p53 in cisplatin nephrotoxicity

Cisplatin is one of the most potent chemotherapy drugs widely used for cancer treatment. However, its use is limited by side effects in normal tissues, particularly the kidneys. Recent studies, using both in vitro and in vivo experimental models, have suggested a critical role for p53 in cisplatin nephrotoxicity. The signaling pathways upstream and downstream of p53 are being investigated and related to renal cell injury and death. Along with the mechanistic studies, renoprotective approaches targeting p53 have been suggested. Further research may integrate p53 signaling with other nephrotoxic signaling pathways, providing a comprehensive understanding of cisplatin nephrotoxicity and leading to the development of effective renoprotective strategies during cancer therapy.