Role of the p38 MAPK pathway in cisplatin-based therapy

Iodine-Biofortified Lettuce Can Promote Mitochondrial Dependent Pathway of Apoptosis in Human Gastrointestinal Cancer Cells

Previously, our research provided evidence that exposure of gastric and colon cancer cells to extracts from iodine-biofortified lettuce leads to a reduction of cell viability and proliferation through cell cycle arrest and upregulation of pro-apoptotic genes. The aim of the present study was to determine the potential cellular mechanisms of induction of cell death in human gastrointestinal cancer cell lines after treatment with iodine-biofortified lettuce. We demonstrated that extracts from lettuce enriched with iodine induce apoptosis in gastric AGS and colon HT-29 cancer cells and the mechanism of programmed cell death may be triggered and executed through different signaling pathways, depending on the type of cells. Western blot analysis revealed that iodine-fortified lettuce leads to cell death through the release of cytochrome c to the cytosolic fraction and activation of the primary drivers of apoptosis: caspase-3, caspase-7, and caspase-9. Furthermore, we have reported that apoptotic effects of lettuce extracts may be mediated by poly (ADP-ribose) polymerase (PARP) and activation of pro-apoptotic Bcl-2 family proteins such as Bad, Bax, and BID. We also observed mitochondrial dysfunction with the dissipation of the mitochondrial membrane potential in cells exposed to lettuce extracts. Taken together, these results indicate that the organic form of iodine such as 5-ISA and 3,5-diISA is an important factor in the activation of intrinsic mitochondrial apoptotic pathway in AGS and HT-29 cancer cells in a p53-independent manner.

Multifunctionality of Calebin A in inflammation, chronic diseases and cancer

Chronic diseases including cancer have high case numbers as well as mortality rates. The efficient treatment of chronic diseases is a major ongoing medical challenge worldwide, because of their complexity and many inflammatory pathways such as JNK, p38/MAPK, MEK/ERK, JAK/STAT3, PI3K and NF-κB among others being implicated in their pathogenesis. Together with the versatility of chronic disease classical mono-target therapies are often insufficient. Therefore, the anti-inflammatory as well as anti-cancer capacities of polyphenols are currently investigated to complement and improve the effect of classical anti-inflammatory drugs, chemotherapeutic agents or to overcome drug resistance of cancer cells. Currently, research on Calebin A, a polyphenolic component of turmeric (Curcuma longa), is becoming of growing interest with regard to novel treatment strategies and has already been shown health-promoting as well as anti-tumor properties, including anti-oxidative and anti-inflammatory effects, in diverse cancer cells. Within this review, we describe already known anti-inflammatory activities of Calebin A via modulation of NF-κB and its associated signaling pathways, linked with TNF-α, TNF-β and COX-2 and further summarize Calebin A's tumor-inhibiting properties that are known up to date such as reduction of cancer cell viability, proliferation as well as metastasis. We also shed light on possible future prospects of Calebin A as an anti-cancer agent.

Multiomic analysis identifies CPT1A as a potential therapeutic target in platinum-refractory, high-grade serous ovarian cancer

Resistance to platinum compounds is a major determinant of patient survival in high-grade serous ovarian cancer (HGSOC). To understand mechanisms of platinum resistance and identify potential therapeutic targets in resistant HGSOC, we generated a data resource composed of dynamic (±carboplatin) protein, post-translational modification, and RNA sequencing (RNA-seq) profiles from intra-patient cell line pairs derived from 3 HGSOC patients before and after acquiring platinum resistance. These profiles reveal extensive responses to carboplatin that differ between sensitive and resistant cells. Higher fatty acid oxidation (FAO) pathway expression is associated with platinum resistance, and both pharmacologic inhibition and CRISPR knockout of carnitine palmitoyltransferase 1A (CPT1A), which represents a rate limiting step of FAO, sensitize HGSOC cells to platinum. The results are further validated in patient-derived xenograft models, indicating that CPT1A is a candidate therapeutic target to overcome platinum resistance. All multiomic data can be queried via an intuitive gene-query user interface (https://sites.google.com/view/ptrc-cell-line).

Mitogen signal-associated pathways, energy metabolism regulation, and mediation of tumor immunogenicity play essential roles in the cellular response of malignant pleural mesotheliomas to platinum-based treatment: a retrospective study

Background

Malignant pleural mesothelioma (MPM) is a rare malignant tumor associated with asbestos exposure, with infaust prognosis and overall survival below 20 months in treated patients. Platinum is still the backbone of the chemotherapy protocols, and the reasons for the rather poor efficacy of platinum compounds in MPM remain largely unknown. Therefore, we aimed to analyze differences in key signaling pathways and biological mechanisms in therapy-naïve samples and samples after chemotherapy in order to evaluate the effect of platinum-based chemotherapy.

Methods

The study cohort comprised 24 MPM tumor specimens, 12 from therapy-naïve and 12 from patients after platinum-based therapy. Tumor samples were screened using the NanoString nCounter platform for digital gene expression analysis with an appurtenant custom-designed panel comprising a total of 366 mRNAs covering the most important tumor signaling pathways. Significant pathway associations were identified by gene set enrichment analysis using the WEB-based GEne SeT AnaLysis Toolkit (WebGestalt)

Results

We have found reduced activity of TNF (normalized enrichment score: 2.03), IL-17 (normalized enrichment score: 1.93), MAPK (normalized enrichment score: 1.51), and relaxin signaling pathways (normalized enrichment score: 1.42) in the samples obtained after platinum-based therapy. In contrast, AMPK (normalized enrichment score: –1.58), mTOR (normalized enrichment score: –1.50), Wnt (normalized enrichment score: –1.38), and longevity regulating pathway (normalized enrichment score: –1.31) showed significantly elevated expression in the same samples.

Conclusions

We could identify deregulated signaling pathways due to a directed cellular response to platinum-induced cell stress. Our results are paving the ground for a better understanding of cellular responses and escape mechanisms, carrying a high potential for improved clinical management of patients with MPM.

Stress-activated kinases as therapeutic targets in pancreatic cancer

Pancreatic cancer is a dismal disease with high incidence and poor survival rates. With the aim to improve overall survival of pancreatic cancer patients, new therapeutic approaches are urgently needed. Protein kinases are key regulatory players in basically all stages of development, maintaining physiologic functions but also being involved in pathogenic processes. c-Jun N-terminal kinases (JNK) and p38 kinases, representatives of the mitogen-activated protein kinases, as well as the casein kinase 1 (CK1) family of protein kinases are important mediators of adequate response to cellular stress following inflammatory and metabolic stressors, DNA damage, and others. In their physiologic roles, they are responsible for the regulation of cell cycle progression, cell proliferation and differentiation, and apoptosis. Dysregulation of the underlying pathways consequently has been identified in various cancer types, including pancreatic cancer. Pharmacological targeting of those pathways has been the field of interest for several years. While success in earlier studies was limited due to lacking specificity and off-target effects, more recent improvements in small molecule inhibitor design against stress-activated protein kinases and their use in combination therapies have shown promising in vitro results. Consequently, targeting of JNK, p38, and CK1 protein kinase family members may actually be of particular interest in the field of precision medicine in patients with highly deregulated kinase pathways related to these kinases. However, further studies are warranted, especially involving in vivo investigation and clinical trials, in order to advance inhibition of stress-activated kinases to the field of translational medicine.

Revisiting Platinum-Based Anticancer Drugs to Overcome Gliomas

Although there are many patients with brain tumors worldwide, there are numerous difficulties in overcoming brain tumors. Among brain tumors, glioblastoma, with a 5-year survival rate of 5.1%, is the most malignant. In addition to surgical operations, chemotherapy and radiotherapy are generally performed, but the patients have very limited options. Temozolomide is the most commonly prescribed drug for patients with glioblastoma. However, it is difficult to completely remove the tumor with this drug alone. Therefore, it is necessary to discuss the potential of anticancer drugs, other than temozolomide, against glioblastomas. Since the discovery of cisplatin, platinum-based drugs have become one of the leading chemotherapeutic drugs. Although many studies have reported the efficacy of platinum-based anticancer drugs against various carcinomas, studies on their effectiveness against brain tumors are insufficient. In this review, we elucidated the anticancer effects and advantages of platinum-based drugs used in brain tumors. In addition, the cases and limitations of the clinical application of platinum-based drugs are summarized. As a solution to overcome these obstacles, we emphasized the potential of a novel approach to increase the effectiveness of platinum-based drugs.

Systematic Investigation of DNA Methylation Associated With Platinum Chemotherapy Resistance Across 13 Cancer Types

Background: Platinum resistance poses a significant problem for oncology clinicians. As a result, the role of epigenetics and DNA methylation in platinum-based chemoresistance has gained increasing attention from researchers in recent years. A systematic investigation of aberrant methylation patterns related to platinum resistance across various cancer types is urgently needed.

Methods: We analyzed the platinum chemotherapy response-related methylation patterns from different perspectives of 618 patients across 13 cancer types and integrated transcriptional and clinical data. Spearman’s test was used to evaluate the correlation between methylation and gene expression. Cox analysis, the Kaplan-Meier method, and log-rank tests were performed to identify potential risk biomarkers based on differentially methylated positions (DMPs) and compare survival based on DMP values. Support vector machines and receiver operating characteristic curves were used to identify the platinum-response predictive DMPs.

Results: A total of 3,703 DMPs (p value < 0.001 and absolute delta beta >0.10) were identified, and the DMP numbers of each cancer type varied. A total of 39.83% of DMPs were hypermethylated and 60.17% were hypomethylated in platinum-resistant patients. Among them, 405 DMPs (Benjamini and Hochberg adjusted p value < 0.05) were found to be associated with prognosis in tumor patients treated with platinum-based regimens, and 664 DMPs displayed the potential to predict platinum chemotherapy response. In addition, we defined six DNA DMPs consisting of four gene members (mesothelin, protein kinase cAMP-dependent type II regulatory subunit beta, msh homeobox 1, and par-6 family cell polarity regulator alpha) that may have favorable prognostic and predictive values for platinum chemotherapy.

Conclusion: The methylation-transcription axis exists and participates in the complex biological mechanism of platinum resistance in various cancers. Six DMPs and four associated genes may have the potential to serve as promising epigenetic biomarkers for platinum-based chemotherapy and guide clinical selection of optimal treatment.

DUSP16 promotes cancer chemoresistance through regulation of mitochondria-mediated cell death

Drug resistance is a major obstacle to the treatment of most human tumors. In this study, we find that dual-specificity phosphatase 16 (DUSP16) regulates resistance to chemotherapy in nasopharyngeal carcinoma, colorectal cancer, gastric and breast cancer. Cancer cells expressing higher DUSP16 are intrinsically more resistant to chemotherapy-induced cell death than cells with lower DUSP16 expression. Overexpression of DUSP16 in cancer cells leads to increased resistance to cell death upon chemotherapy treatment. In contrast, knockdown of DUSP16 in cancer cells increases their sensitivity to treatment. Mechanistically, DUSP16 inhibits JNK and p38 activation, thereby reducing BAX accumulation in mitochondria to reduce apoptosis. Analysis of patient survival in head & neck cancer and breast cancer patient cohorts supports DUSP16 as a marker for sensitivity to chemotherapy and therapeutic outcome. This study therefore identifies DUSP16 as a prognostic marker for the efficacy of chemotherapy, and as a therapeutic target for overcoming chemoresistance in cancer.

Bromamine T (BAT) Exerts Stronger Anti-Cancer Properties than Taurine (Tau)

BACKGROUND

Taurine (Tau) ameliorates cancer pathogenesis. Researchers have focused on the functional properties of bromamine T (BAT), a stable active bromine molecule. Both N-bromotaurine (TauNHBr) and BAT exert potent anti-inflammatory properties, but the landscape remains obscure concerning the anti-cancer effect of BAT.

METHODS

We used Crystal Violet, colony formation, flow cytometry and Western blot experiments to evaluate the effect of BAT and Tau on the apoptosis and autophagy of cancer cells. Xenograft experiments were used to determine the in vivo cytotoxicity of either agent.

RESULTS

We demonstrated that both BAT and Tau inhibited the growth of human colon, breast, cervical and skin cancer cell lines. Among them, BAT exerted the greatest cytotoxic effect on both RKO and MDA-MB-468 cells. In particular, BAT increased the phosphorylation of c-Jun N-terminal kinases (JNK½), p38 mitogen-activated protein kinase (MAPK), and extracellular-signal-regulated kinases (ERK½), thereby inducing mitochondrial apoptosis and autophagy in RKO cells. In contrast, Tau exerted its cytotoxic effect by upregulating JNK½ forms, thus triggering mitochondrial apoptosis in RKO cells. Accordingly, colon cancer growth was impaired in vivo.

CONCLUSIONS

BAT and Tau exerted their anti-tumor properties through the induction of (i) mitochondrial apoptosis, (ii) the MAPK family, and iii) autophagy, providing novel anti-cancer therapeutic modalities.

Analysis of pulsed cisplatin signalling dynamics identifies effectors of resistance in lung adenocarcinoma

The identification of clinically viable strategies for overcoming resistance to platinum chemotherapy in lung adenocarcinoma has previously been hampered by inappropriately tailored in vitro assays of drug response. Therefore, using a pulse model that closely mimics the in vivo pharmacokinetics of platinum therapy, we profiled cisplatin-induced signalling, DNA-damage and apoptotic responses across a panel of human lung adenocarcinoma cell lines. By coupling this data to real-time, single-cell imaging of cell cycle and apoptosis we provide a fine-grained stratification of response, where a P70S6K-mediated signalling axis promotes resistance on a TP53 wildtype or null background, but not a mutant TP53 background. This finding highlights the value of in vitro models that match the physiological pharmacokinetics of drug exposure. Furthermore, it also demonstrates the importance of a mechanistic understanding of the interplay between somatic mutations and the signalling networks that govern drug response for the implementation of any consistently effective, patient-specific therapy.

Lung adenocarcinoma is the most common type of lung cancer, and it emerges because of a variety of harmful genetic changes, or mutations. Two lung cancer patients – or indeed, two different sets of cancerous cells within a patient – may therefore carry different damaging mutations.

A group of drugs called platinum-based chemotherapies are currently the most effective way to treat lung adenocarcinoma. Yet, only 30% of patients actually respond to the therapy. Many studies conducted in laboratory settings have tried to understand why most cases are resistant to treatment, with limited success.

Here, Hastings, Gonzalez-Rajal et al. propose that previous research has been inconclusive because studies done in the laboratory do not reflect how the treatment is actually administered. In patients, platinum-based drugs are cleared from the body within a few hours, but during experiments, the treatment is continually administered to cells growing in a dish.

Hastings, Gonzalez-Rajal et al. therefore developed a laboratory method that mimics the way cells are exposed to platinum-based chemotherapy in the body. These experiments showed that the lung adenocarcinoma cells which resisted treatment also carried high levels of a protein known as P70S6K. Pairing platinum-based chemotherapy with a drug that blocks the activity of P70S6K killed these resistant cells. This combination also treated human lung adenocarcinoma tumours growing under the skin of mice. However, it was ineffective on cancerous cells that carry a mutation in a protein called p53, which is often defective in cancers.

Overall, this work demonstrates the need to refine how drugs are tested in the laboratory to better reflect real-life conditions. It also underlines the importance of personalizing drug combinations to the genetic background of each tumour, a concept that will be vital to consider in future clinical trials.

14,15β-dihydroxyklaineanone inhibits HepG2 cell proliferation and migration through p38MAPK pathway

OBJECTIVES

Eurycoma longifolia Jack (Simaroubaceae) is commonly distributed in the Southeast Asia and Indo China, which has been shown to possess antianxiety, antibacterial, anticancer, antifungal, anti-inflammatory, antimalarial and antioxidant biological activities. 14,15β-dihydroxyklaineanone is a diterpene isolated from E. longifolia Jack, which is cytotoxic against human lung cancer and human breast cancer cell lines. However, the effects and underlying mechanisms of 14,15β-dihydroxyklaineanone on hepatocellular carcinoma remain unknown.

METHODS

Cell viability assay and colony formation assay were used to measure HepG2 cell proliferation. Flow cytometry was used to analyse cell cycle and apoptosis. Wound-healing assay and transwell assay were used to observe cells migration. RNA sequencing and the enrichment of differentially expressed genes (DEGs) in Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were used to find and determine underlying pathways.

KEY FINDINGS

We found that 14,15β-dihydroxyklaineanone inhibited the growth and migration of HepG2 cells but did not induce cell apoptosis. 14,15β-dihydroxyklaineanone induced S cell cycle arrest by downregulating the expression levels of cyclin A, p-CDK2, cyclin B1, p21, E2F-1 and PCNA. In addition, RNA sequencing showed that 14,15β-dihydroxyklaineanone regulated MAPK pathway by increasing the expression levels of phosphor-p38. Downregulating of p38 via both p38 inhibitor (SB203580) and p38-siRNA could antagonize the inhibition of cell proliferation and migration and reverse the changes in p-p38, E-cadherin, N-cadherin and PCNA expression induced by 14,15β-dihydroxyklaineanone treatment.

CONCLUSIONS

14,15β-dihydroxyklaineanone inhibited cell proliferation and migration through regulating p38 MAPK pathway in HCC cells.

The p38 MAPK Signaling Activation in Colorectal Cancer upon Therapeutic Treatments

Pharmacological treatment of colorectal carcinoma currently proceeds through the administration of a combination of different chemotherapeutic agents. In the case of rectal carcinoma, radiation therapy also represents a therapeutic strategy. In an attempt at translating much-needed new targeted therapy to the clinics, p38 mitogen activated protein kinase (MAPK) inhibitors have been tested in clinical trials involving colorectal carcinoma patients, especially in combination with chemotherapy; however, despite the high expectations raised by a clear involvement of the p38 MAPK pathway in the response to therapeutic treatments, poor results have been obtained so far. In this work, we review recent insights into the exact role of the p38 MAPK pathway in response to currently available therapies for colorectal carcinoma, depicting an intricate scenario in which the p38 MAPK node presents many opportunities, as well as many challenges, for its perspective exploitation for clinical purposes.

Toll-like Receptors from the Perspective of Cancer Treatment

Toll-like receptors (TLRs) represent a family of pattern recognition receptors that recognize certain pathogen-associated molecular patterns and damage-associated molecular patterns. TLRs are highly interesting to researchers including immunologists because of the involvement in various diseases including cancers, allergies, autoimmunity, infections, and inflammation. After ligand engagement, TLRs trigger multiple signaling pathways involving nuclear factor-κB (NF-κB), interferon-regulatory factors (IRFs), and mitogen-activated protein kinases (MAPKs) for the production of various cytokines that play an important role in diseases like cancer. TLR activation in immune as well as cancer cells may prevent the formation and growth of a tumor. Nonetheless, under certain conditions, either hyperactivation or hypoactivation of TLRs supports the survival and metastasis of a tumor. Therefore, the design of TLR-targeting agonists as well as antagonists is a promising immunotherapeutic approach to cancer. In this review, we mainly describe TLRs, their involvement in cancer, and their promising properties for anticancer drug discovery.

Tandem RNA isolation reveals functional rearrangement of RNA-binding proteins on CDKN1B/p27Kip1 3'UTRs in cisplatin treated cells

Post-transcriptional control of gene expression is mediated via RNA-binding proteins (RBPs) that interact with mRNAs in a combinatorial fashion. While recent global RNA interactome capture experiments expanded the repertoire of cellular RBPs quiet dramatically, little is known about the assembly of RBPs on particular mRNAs; and how these associations change and control the fate of the mRNA in drug-treatment conditions. Here we introduce a novel biochemical approach, termed tobramycin-based tandem RNA isolation procedure (tobTRIP), to quantify proteins associated with the 3ʹUTRs of cyclin-dependent kinase inhibitor 1B (CDKN1B/p27^Kip1) mRNAs in vivo. P27^Kip1 plays an important role in mediating a cell’s response to cisplatin (CP), a widely used chemotherapeutic cancer drug that induces DNA damage and cell cycle arrest. We found that p27^Kip1 mRNA is stabilized upon CP treatment of HEK293 cells through elements in its 3ʹUTR. Applying tobTRIP, we further compared the associated proteins in CP and non-treated cells, and identified more than 50 interacting RBPs, many functionally related and evoking a coordinated response. Knock-downs of several of the identified RBPs in HEK293 cells confirmed their involvement in CP-induced p27 mRNA regulation; while knock-down of the KH-type splicing regulatory protein (KHSRP) further enhanced the sensitivity of MCF7 adenocarcinoma cancer cells to CP treatment. Our results highlight the benefit of specific in vivo mRNA-protein interactome capture to reveal post-transcriptional regulatory networks implicated in cellular drug response and adaptation.

Novel targeted strategies to overcome resistance in small-cell lung cancer: focus on PARP inhibitors and rovalpituzumab tesirine

Introduction: Small-cell lung cancer (SCLC) is a highly aggressive neuroendocrine tumour, and its outcome is strongly conditioned by the rapid onset of resistance to conventional chemotherapeutics. First-line treatment with a combination of platinum agents and topoisomerase inhibitors has been the standard of care for over 30 years, with disappointing clinical outcome caused by early-acquired chemoresistance. In this disheartening scenario, novel treatment strategies are being implemented in order to either revert or bypass resistance mechanisms. Areas covered: The general mechanism of action of the standard frontline treatment regimens for SCLC, as well as the known resistance mechanisms to these drugs, is reviewed. Moreover, we focus on the current preclinical and clinical evidence on the potential role of PARP inhibitors and rovalpituzumab tesirine (Rova-T) to tackle chemoresistance in SCLC. Expert opinion: Preliminary evidence supports PARP inhibitors and Rova-T as two promising approaches to either revert or bypass chemoresistance in SCLC, respectively. The identification of potential predictive biomarkers of response to these innovative treatments (SLFN11 and DLL3) has shortened the gap between SCLC and personalized targeted therapy. Further large-scale clinical studies are urgently needed for a better designation of PARP inhibitors and Rova-T in the therapeutic algorithm of SCLC patients.

Mode of photoexcited C60 fullerene involvement in potentiating cisplatin toxicity against drug-resistant L1210 cells

Introduction: C₆₀ fullerene has received great attention as a candidate for biomedical applications. Due to unique structure and properties, C₆₀ fullerene nanoparticles are supposed to be useful in drug delivery, photodynamic therapy (PDT) of cancer, and reversion of tumor cells’ multidrug resistance. The aim of this study was to elucidate the possible molecular mechanisms involved in photoexcited C₆₀ fullerene-dependent enhancement of cisplatin toxicity against leukemic cells resistant to cisplatin.

Methods: Stable homogeneous pristine C₆₀ fullerene aqueous colloid solution (10^-4 М, purity 99.5%) was used in the study. The photoactivation of C₆₀ fullerene accumulated by L1210R cells was done by irradiation in microplates with light-emitting diode lamp (420-700 nm light, 100 mW·cm^-2). Cells were further incubated with the addition of Cis-Pt to a final concentration of 1 μg/mL. Activation of p38 MAPK was visualized by Western blot analysis. Flow cytometry was used for the estimation of cells distribution on cell cycle. Mitochondrial membrane potential (Δψ_m) was estimated with the use of fluorescent potential-sensitive probe TMRE (Tetramethylrhodamine Ethyl Ester).

Results: Cis-Pt applied alone at 1 μg/mL concentration failed to affect mitochondrial membrane potential in L1210R cells or cell cycle distribution as compared with untreated cells. Activation of ROS-sensitive proapoptotic p38 kinase and enhanced content of cells in subG1 phase were detected after irradiation of L1210R cells treated with 10^-5M C₆₀ fullerene. Combined treatment with photoexcited C₆₀ fullerene and Cis-Pt was followed by the dissipation of Δψ_m at early-term period, blockage of cell transition into S phase, and considerable accumulation of cells in proapoptotic subG1 phase at prolonged incubation.

Conclusion: The effect of the synergic cytotoxic activity of both agents allowed to suppose that photoexcited C₆₀ fullerene promoted Cis-Pt accumulation in leukemic cells resistant to Cis-Pt. The data obtained could be useful for the development of new approaches to overcome drug-resistance of leukemic cells.

Bag-1 silencing enhanced chemotherapeutic drug-induced apoptosis in MCF-7 breast cancer cells affecting PI3K/Akt/mTOR and MAPK signaling pathways

The multifunctional anti-apoptotic Bag-1 protein has important roles in apoptosis, proteasome-mediated degradation, transcriptional regulation, and intracellular signaling. Bag-1 promotes cell survival and proliferation, and is overexpressed in breast cancer. Therefore, Bag-1-targeted therapy might be a promising strategy to treat breast cancer. However, the effects of Bag-1 silencing in combination with conventional chemotherapeutic drugs on cell viability and major signaling pathways have not yet been fully investigated in breast cancer cells. In this study, we investigated the cytotoxic effects of Bag-1 silencing, alone and in combination with cisplatin or paclitaxel treatment, in MCF-7 breast cancer cells. Bag-1 knockdown by shRNA or siRNA transfection sensitized MCF-7 cells to apoptosis induced by cisplatin or paclitaxel. Combination of Bag-1 silencing and drug treatment more potently downregulated the pro-survival PI3K/Akt/mTOR and p44/42 mitogen activated protein kinase (MAPK) pathways, and more potently upregulated the stress-activated p38 and SAPK/JNK MAPK pathways. Bag-1-silenced drug-treated cells had also highly reduced proliferative capacity, downregulated cyclin-cyclin dependent kinase complexes and upregulated tumor suppressors p21 and Rb. These results overall indicated that Bag-1 silencing enhanced cisplatin- or paclitaxel-induced cytotoxicity through multiple pathways. In conclusion, Bag-1 targeted therapy might enhance the therapeutic potential of conventional anti-cancer drugs in the treatment of breast cancer.

A Ruthenium(II) N-Heterocyclic Carbene (NHC) Complex with Naphthalimide Ligand Triggers Apoptosis in Colorectal Cancer Cells via Activating the ROS-p38 MAPK Pathway

The p38 MAPK pathway is known to influence the anti-tumor effects of several chemotherapeutics, including that of organometallic drugs. Previous studies have demonstrated the important role of p38 both as a regulator and a sensor of cellular reactive oxygen species (ROS) levels. Investigating the anti-cancer properties of novel 1,8-naphthalimide derivatives containing Rh(I) and Ru(II) N-heterocyclic carbene (NHC) ligands, we observed a profound induction of ROS by the complexes, which is most likely generated from mitochondria (mtROS). Further analyses revealed a rapid and consistent activation of p38 signaling by the naphthalimide-NHC conjugates, with the Ru(II) analogue—termed MC6—showing the strongest effect. In view of this, genetic as well as pharmacological inhibition of p38α, attenuated the anti-proliferative and pro-apoptotic effects of MC6 in HCT116 colon cancer cells, highlighting the involvement of this signaling molecule in the compound’s toxicity. Furthermore, the influence of MC6 on p38 signaling appeared to be dependent on ROS levels as treatment with general- and mitochondria-targeted anti-oxidants abrogated p38 activation in response to MC6 as well as the molecule’s cytotoxic- and apoptogenic response in HCT116 cells. Altogether, our results provide new insight into the molecular mechanisms of naphthalimide-metal NHC analogues via the ROS-induced activation of p38 MAPK, which may have therapeutic interest for the treatment of various cancer types.

Aurantoside C Targets and Induces Apoptosis in Triple Negative Breast Cancer Cells

Triple negative breast cancer (TNBC) is a subtype of breast cancers that currently lacks effective targeted therapy. In this study, we found that aurantoside C (C828), isolated from the marine sponge Manihinealynbeazleyae collected from Western Australia, exhibited higher cytotoxic activities in TNBC cells compared with non-TNBC (luminal and normal-like) cells. The cytotoxic effect of C828 was associated to the accumulation of cell at S-phase, resulting in the decline of cyclin D1, cyclin E1, CDK4, and CDK6, and an increase in p21. We also found that C828 inhibited the phosphorylation of Akt/mTOR and NF-kB pathways and increased the phosphorylation of p38 MAPK and SAPK/JNK pathways, leading to apoptosis in TNBC cells. These effects of C828 were not observed in non-TNBC cells at the concentrations that were cytotoxic to TNBC cells. When compared to the cytotoxic effect with the chemotherapeutic drugs doxorubicin and cisplatin, C828 was found to be 20 times and 35 times more potent than doxorubicin and cisplatin, respectively. These results indicate that C828 could be a promising lead for developing new anticancer agents that target TNBC cells.

Pharmacological Inhibition of p38 MAPK by SB203580 Increases Resistance to Carboplatin in A2780cp Cells and Promotes Growth in Primary Ovarian Cancer Cells

Chemoresistance renders current chemotherapy regimens ineffective against advanced epithelial ovarian cancer (EOC). Carboplatin (the first-line chemotherapeutic agent to treat EOC) induces cell death by regulating multiple signaling pathways. The objective of this study is to identify the signaling pathways that contribute to carboplatin resistance in EOC. To this end, we performed a proteome profiler human phospho-kinase array experiment and compared the phosphorylation profiles between the cisplatin-sensitive A2780s versus its derivative cisplatin-resistant A2780cp cells. The phospho-kinase array revealed that A2780s and A2780cp cells displayed different profiles in basal and carboplatin-induced phosphorylation. Phosphorylation of p38 MAPK was increased by carboplatin more markedly in A2780s cells compared to A2780cp cells. Inhibition of p38 MAPK activity by its specific inhibitor SB203580 increased resistance to carboplatin in A2780cp cells, but not in A2780s cells or in ascites-derived high-grade serous EOC cells. Interestingly, SB203580 increased the number of viable cells in the primary EOC cells, which was concomitant with an increase in survivin expression. In conclusion, inhibition of p38 MAPK by SB203580 increases resistance to carboplatin in A2780cp cells and the number of viable cells in the primary EOC cells, suggesting that pharmacological inhibition of p38 MAPK might not be an effective therapeutic strategy for EOC.

DUSP1 enhances the chemoresistance of gallbladder cancer via the modulation of the p38 pathway and DNA damage/repair system

Cisplatin (CDDP) is a commonly used drug for gallbladder cancer (GBC) chemotherapy. However, resistance to CDDP treatment results in relapse. Therefore, there is a need for the development of more effective treatment strategies to overcome chemoresistance. Dual-specificity phosphatase 1 (DUSP1) was reported to be involved in the resistance of a number of chemotherapeutic agents and was revealed to be highly expressed in CDDP-resistant GBC cells and CDDP-treated tumor types compared with normal cells or tissues in the present study. DUSP1 was revealed to inhibit the cytotoxicity of CDDP in two GBC cell lines, SGC996 and GBC-SD. P38 mitogen-activated protein kinases may be involved in the mechanism of chemoresistance. Furthermore, the number of DNA double-strand breaks in SGC996 OE cells was reduced compared with SGC996 vector cells indicating DUSP1 may attenuate the chemotherapeutic efficiency. Due to its potency against CDDP treatment, DUSP1 may be a promising target to overcome chemoresistance in GBC therapy.

Tantalum Sulfide Nanosheets as a Theranostic Nanoplatform for Computed Tomography Imaging-Guided Combinatorial Chemo-Photothermal Therapy

Near-infrared (NIR)-absorbing metal-based nanomaterials have shown tremendous potential for cancer therapy, given their facile and controllable synthesis, efficient photothermal conversion, capability of spatiotemporal-controlled drug delivery, and intrinsic imaging function. Tantalum (Ta) is among the most biocompatible metals and arouses negligible adverse biological responses in either oxidized or reduced forms, and thus Ta-derived nanomaterials represent promising candidates for biomedical applications. However, Ta-based nanomaterials by themselves have not been explored for NIR-mediated photothermal ablation therapy. In this work, we report an innovative Ta-based multifunctional nanoplatform composed of biocompatible tantalum sulfide (TaS2) nanosheets (NSs) for simultaneous NIR hyperthermia, drug delivery, and computed tomography (CT) imaging. The TaS2 NSs exhibit multiple unique features including (i) efficient NIR light-to-heat conversion with a high photothermal conversion efficiency of 39%. (ii) high drug loading (177% by weight), (iii) controlled drug release triggered by NIR light and moderate acidic pH, (iv) high tumor accumulation via heat-enhanced tumor vascular permeability, (v) complete tumor ablation and negligible side effects, and (vi) comparable CT imaging contrast efficiency to the widely clinically used agent iobitridol. We expect that this multifunctional NS platform can serve as a promising candidate for imaging-guided cancer therapy and selection of cancer patients with high tumor accumulation.

Exploration of the sequential gene changes in epithelial ovarian cancer induced by carboplatin via microarray analysis

The purpose of the current study was to explore the carboplatin-induced sequential changes in gene expression and screen out key genes, which were associated with effects of carboplatin on epithelial ovarian cancer (EOC). The microarray dataset GSE13525 was downloaded from the Gene Expression Omnibus database, including 6 EOC cell samples separately treated with carboplatin at 24, 30 and 36 h (case group), and 6 samples treated with phosphate-buffered saline at the same time points (control group). A total of 3 sets of differentially expressed genes (DEGs) were respectively identified in case samples at 24, 30 and 36 h compared with the control group via the Limma package, and separately recorded as DEG-24, DEG-30 and DEG-36. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis of the overlapped DEGs were performed via the Database for Annotation, Visualization and Integrated Discovery. The protein-protein interaction (PPI) network was constructed and analyzed by Cytoscape software. In addition, the survival curves were drawn to illustrate the association between the expression levels of certain critical genes and the prognosis of EOC. A total of 170, 605 and 1043 DEGs were separately obtained in DEG-24 DEG-30 and DEG-36, and 110 overlaps were identified. The overlaps were enriched in 77 GO terms and 3 KEGG pathways. A total of 152 pairs were involved in the PPI network, and the abnormal expression levels (high or low) of c-Jun and cyclin B1 (CCNB1) would reduce the survival time of patients with EOC. The study indicated that c-Jun and CCNB1 may be the prognostic biomarkers of EOC treated with carboplatin, and certain pathways (such as p53 signaling pathway, cell cycle and mitogen-activation protein kinase signaling pathway) may be involved in carboplatin-resistant EOC.

Common Chemical Inductors of Replication Stress: Focus on Cell-Based Studies

DNA replication is a highly demanding process regarding the energy and material supply and must be precisely regulated, involving multiple cellular feedbacks. The slowing down or stalling of DNA synthesis and/or replication forks is referred to as replication stress (RS). Owing to the complexity and requirements of replication, a plethora of factors may interfere and challenge the genome stability, cell survival or affect the whole organism. This review outlines chemical compounds that are known inducers of RS and commonly used in laboratory research. These compounds act on replication by direct interaction with DNA causing DNA crosslinks and bulky lesions (cisplatin), chemical interference with the metabolism of deoxyribonucleotide triphosphates (hydroxyurea), direct inhibition of the activity of replicative DNA polymerases (aphidicolin) and interference with enzymes dealing with topological DNA stress (camptothecin, etoposide). As a variety of mechanisms can induce RS, the responses of mammalian cells also vary. Here, we review the activity and mechanism of action of these compounds based on recent knowledge, accompanied by examples of induced phenotypes, cellular readouts and commonly used doses.

miR-625-3p regulates oxaliplatin resistance by targeting MAP2K6-p38 signalling in human colorectal adenocarcinoma cells

Oxaliplatin resistance in colorectal cancers (CRC) is a major medical problem, and predictive markers are urgently needed. Recently, miR-625-3p was reported as a promising predictive marker. Herein, we show that miR-625-3p functionally induces oxaliplatin resistance in CRC cells, and identify the signalling networks affected by miR-625-3p. We show that the p38 MAPK activator MAP2K6 is a direct target of miR-625-3p, and, accordingly, is downregulated in non-responder patients of oxaliplatin therapy. miR-625-3p-mediated resistance is reversed by anti-miR-625-3p treatment and ectopic expression of a miR-625-3p insensitive MAP2K6 variant. In addition, reduction of p38 signalling by using siRNAs, chemical inhibitors or expression of a dominant-negative MAP2K6 protein induces resistance to oxaliplatin. Transcriptome, proteome and phosphoproteome profiles confirm inactivation of MAP2K6-p38 signalling as one likely mechanism of oxaliplatin resistance. Our study shows that miR-625-3p induces oxaliplatin resistance by abrogating MAP2K6-p38-regulated apoptosis and cell cycle control networks, and corroborates the predictive power of miR-625-3p.

p38MAPK and Chemotherapy: We Always Need to Hear Both Sides of the Story

The p38MAPK signaling pathway was initially described as a stress response mechanism. In fact, during previous decades, it was considered a pathway with little interest in oncology especially in comparison with other MAPKs such as ERK1/2, known to be target of oncogenes like Ras. However, its involvement in apoptotic cell death phenomena makes this signaling pathway more attractive for many cancer research laboratories. This apoptotic role allows to establish a link between p38MAPK and regular chemotherapeutic agents such as Cisplatin or base analogs (Cytarabine, Gemcitabine or 5-Fluorouracil) which are currently used in hospitals across the world. In fact, and more recently, p38MAPK has also been connected with targeted therapies like tyrosine kinase inhibitors (vg. Imatinib, Sorafenib) and, to a lesser extent, with monoclonal antibodies. In addition, the oncogenic or tumor suppressor potential of this signaling pathway has aroused the interest of the scientific community in evaluating p38MAPK as a novel target for cancer therapy. In this review, we will summarize the role of p38MAPK in chemotherapy as well as the potential that p38MAPK inhibition can bring to cancer therapy. All the evidences suggest that p38MAPK could be a double-edged sword and that the search for the most appropriate candidate patients, depending on their pathology and treatment, will lead to a more rational use of this new therapeutic tool.

Exploiting the potential of autophagy in cisplatin therapy: A new strategy to overcome resistance

Resistance to cisplatin is a major challenge in the current cancer therapy. In order to explore new therapeutic strategies to cisplatin resistance, we evaluated, in a model of lung cancer (H1299 and H460 cell lines), the nature of the pathways leading to cell death. We observed that H1299 displayed a natural resistance to cisplatin due to an inability to trigger an apoptotic response that correlates with the induction of autophagy. However, pharmacological and genetic approaches showed how autophagy was a mechanism associated to cell death rather than to resistance. Indeed, pro-autophagic stimuli such as mTOR or Akt inhibition mediate cell death in both cell lines to a similar extent. We next evaluated the response to a novel platinum compound, monoplatin, able to promote cell death in an exclusive autophagy-dependent manner. In this case, no differences were observed between both cell lines. Furthermore, in response to monoplatin, two molecular hallmarks of cisplatin response (p53 and MAPKs) were not implicated, indicating the ability of this pro-autophagic compound to overcome cisplatin resistance. In summary, our data highlight how induction of autophagy could be used in cisplatin resistant tumours and an alternative treatment for p53 mutated patient in a synthetic lethally approach.

An African-specific polymorphism in the TP53 gene impairs p53 tumor suppressor function in a mouse model

In this study, Jennis et al. characterize the first mouse model of an African-specific naturally occurring coding region variant at codon 47 of the p53 tumor suppressor gene (S47). They show that homozygous S47 mice are markedly tumor-prone and that the S47 variant impairs not only p53-mediated cell death but also the ability of p53 to transactivate a subset of genes involved in metabolism and ferroptosis.

A nonsynonymous single-nucleotide polymorphism at codon 47 in TP53 exists in African-descent populations (P47S, rs1800371; referred to here as S47). Here we report that, in human cell lines and a mouse model, the S47 variant exhibits a modest decrease in apoptosis in response to most genotoxic stresses compared with wild-type p53 but exhibits a significant defect in cell death induced by cisplatin. We show that, compared with wild-type p53, S47 has nearly indistinguishable transcriptional function but shows impaired ability to transactivate a subset of p53 target genes, including two involved in metabolism: Gls2 (glutaminase 2) and Sco2. We also show that human and mouse cells expressing the S47 variant are markedly resistant to cell death by agents that induce ferroptosis (iron-mediated nonapoptotic cell death). We show that mice expressing S47 in homozygous or heterozygous form are susceptible to spontaneous cancers of diverse histological types. Our data suggest that the S47 variant may contribute to increased cancer risk in individuals of African descent, and our findings highlight the need to assess the contribution of this variant to cancer risk in these populations. These data also confirm the potential relevance of metabolism and ferroptosis to tumor suppression by p53.

Cytokine overproduction and crosslinker hypersensitivity are unlinked in Fanconi anemia macrophages

The Fanconi anemia proteins participate in a canonical pathway that repairs cross-linking agent-induced DNA damage. Cells with inactivated Fanconi anemia genes are universally hypersensitive to such agents. Fanconi anemia-deficient hematopoietic stem cells are also hypersensitive to inflammatory cytokines, and, as importantly, Fanconi anemia macrophages overproduce such cytokines in response to TLR4 and TLR7/8 agonists. We questioned whether TLR-induced DNA damage is the primary cause of aberrantly regulated cytokine production in Fanconi anemia macrophages by quantifying TLR agonist-induced TNF-α production, DNA strand breaks, crosslinker-induced chromosomal breakage, and Fanconi anemia core complex function in Fanconi anemia complementation group C-deficient human and murine macrophages. Although both M1 and M2 polarized Fanconi anemia cells were predictably hypersensitive to mitomycin C, only M1 macrophages overproduced TNF-α in response to TLR-activating signals. DNA damaging agents alone did not induce TNF-α production in the absence of TLR agonists in wild-type or Fanconi anemia macrophages, and mitomycin C did not enhance TLR responses in either normal or Fanconi anemia cells. TLR4 and TLR7/8 activation induced cytokine overproduction in Fanconi anemia macrophages. Also, although TLR4 activation was associated with induced double strand breaks, TLR7/8 activation was not. That DNA strand breaks and chromosome breaks are neither necessary nor sufficient to account for the overproduction of inflammatory cytokines by Fanconi anemia cells suggests that noncanonical anti-inflammatory functions of Fanconi anemia complementation group C contribute to the aberrant macrophage phenotype and suggests that suppression of macrophage/TLR hyperreactivity might prevent cytokine-induced stem cell attrition in Fanconi anemia.

3D tumor tissue analogs and their orthotopic implants for understanding tumor-targeting of microenvironment-responsive nanosized chemotherapy and radiation

An appropriate representation of the tumor microenvironment in tumor models can have a pronounced impact on directing combinatorial treatment strategies and cancer nanotherapeutics. The present study develops a novel 3D co-culture spheroid model (3D TNBC) incorporating tumor cells, endothelial cells and fibroblasts as color-coded murine tumor tissue analogs (TTA) to better represent the tumor milieu of triple negative breast cancer in vitro. Implantation of TTA orthotopically in nude mice, resulted in enhanced growth and aggressive metastasis to ectopic sites. Subsequently, the utility of the model is demonstrated for preferential targeting of irradiated tumor endothelial cells via radiation-induced stromal enrichment of galectin-1 using anginex conjugated nanoparticles (nanobins) carrying arsenic trioxide and cisplatin. Demonstration of a multimodal nanotherapeutic system and inclusion of the biological response to radiation using an in vitro/in vivo tumor model incorporating characteristics of tumor microenvironment presents an advance in preclinical evaluation of existing and novel cancer nanotherapies.

FROM THE CLINICAL EDITOR

Existing in-vivo tumor models are established by implanting tumor cells into nude mice. Here, the authors described their approach 3D spheres containing tumor cells, enodothelial cells and fibroblasts. This would mimic tumor micro-environment more realistically. This interesting 3D model should reflect more accurately tumor response to various drugs and would enable the design of new treatment modalities.

p38 mitogen-activated protein kinase inhibits USP22 transcription in HeLa cells

Elevated expression of ubiquitin-specific processing enzyme 22 (USP22) was identified in multiple types of human cancers, and was correlated with tumorigenesis and progression. Despite an increase in the numbers of studies in the physiological function of USP22, little is known regarding the regulation of its expression. The 5' flanking sequence of the USP22 gene was recently characterized. In the present study, USP22 transcription was regulated by p38 mitogen-activated protein kinase (MAPK). Treatment of human cervical carcinoma (HeLa) cells with SB203580, an inhibitor of p38 MAPK, enhanced basal USP22 promoter activity and mRNA abundance. Transfection of MAPK kinase 6 (MKK6), an upstream activator of p38 MAPK, resulted in a 40% decrease in USP22 mRNA, while the dominant negative MKK6 increased the transcription level of the USP22, similar to SB203580. Dual luciferase report assays showed that mutations of the Sp1 binding site ahead of the transcription start site abolished the promoting effect of the USP22 promoter by SB203580. Cisplatin, the activator of p38 MAPK, also suppressed USP22 expression. This suppression was blocked by SB203580. In conclusion, p38 MAPK acts as an upstream negative regulator of USP22 transcription in HeLa cells.

The palladacycle, AJ-5, exhibits anti-tumour and anti-cancer stem cell activity in breast cancer cells

Breast cancer is the most common malignancy amongst women worldwide but despite enormous efforts to address this problem, there is still limited success with most of the current therapeutic strategies. The current study describes the anti-cancer activity of a binuclear palladacycle complex (AJ-5) in oestrogen receptor positive (MCF7) and oestrogen receptor negative (MDA-MB-231) breast cancer cells as well as human breast cancer stem cells. AJ-5 is shown to induce DNA double strand breaks leading to intrinsic and extrinsic apoptosis and autophagy cell death pathways which are mediated by the p38 MAP kinase. This study provides evidence that AJ-5 is potentially an effective compound in the treatment of breast cancer.

Use of herbal medicines and natural products: an alternative approach to overcoming the apoptotic resistance of pancreatic cancer

Pancreatic cancer has a poor prognosis with a 5-year survival rate of <5%. It does not respond well to either chemotherapy or radiotherapy, due partly to apoptotic resistance (AR) of the cancer cells. AR has been attributed to certain genetic abnormalities or defects in apoptotic signaling pathways. In pancreatic cancer, significant mutations of K-ras and p53, constitutive activation of NFκB, over-expression of heat shock proteins (Hsp90, Hsp70), histone deacetylase (HDACs) and the activities of other proteins (COX-2, Nrf2 and bcl-2 family members) are closely linked with resistance to apoptosis and invasion. AR has also been associated with aberrant signaling of MAPK, PI3K-AKT, JAK/STAT, SHH, Notch, and Wnt/β-catenin pathways. Strategies targeting these signaling molecules and pathways provide an alternative for overcoming AR in pancreatic cancer. The use of herbal medicines or natural products (HM/NPs) alone or in combination with conventional anti-cancer agents has been shown to produce beneficial effects through actions upon multiple molecular pathways involved in AR. The current standard first-line chemotherapeutic agents for pancreatic cancer are gemcitabine (Gem) or Gem-containing combinations; however, the efficacy is dissatisfied and this limitation is largely attributed to AR. Meanwhile, emerging data have pointed to a combination of HM/NPs that may augment the sensitivity of pancreatic cancer cells to Gem. Greater understanding of how these compounds affect the molecular mechanisms of apoptosis may propel development of HM/NPs as anti-cancer agents and/or adjuvant therapies forward. In this review, we give a critical appraisal of the use of HM/NPs alone and in combination with anti-cancer drugs. We also discuss the potential regulatory mechanisms whereby AR is involved in these protective pathways.

A small molecule, MTBT, prevents cancer cell growth by activating p38 MAPK

Cancer is a disease of unscheduled cell division and many anticancer drugs target the cell cycle to inhibit the proliferation of cancer cells. We conducted a screen for new anticancer drugs that induce cell cycle arrest using a small compound library. From this screen, we identified 2-(3-methyl-thiophen-2-yl)-4-(3,4-dioxybenzene) thiazole (MTBT), which causes accumulation of cancer cells with 4N DNA content and inhibits colony formation of several cancer cell lines. We further showed that the treatment of cancer cells with this compound for a longer time period leads to apoptosis, as indicated by the presence of cells with a sub-G1 peak and the appearance apoptotic markers. The increased phosphorylation of serine 10 on histone H3 in MTBT-treated cancer cells suggests cell cycle arrest in the M-phase. Strikingly, MTBT-induced cell cycle arrest and enhanced H3 (Ser10) phosphorylation are abrogated by the pretreatment with SB203580, a specific inhibitor of mitogen-activated protein kinase p38. Moreover, treatment of cancer cells with MTBT induces the phosphorylation of p38, indicative of p38 activation. Together, we have identified a new compound that inhibits cancer cell proliferation, which is likely a consequence of p38 activation.

HIV-TAT mediated protein transduction of Cu/Zn-superoxide dismutase-1 (SOD1) protects skin cells from ionizing radiation

Background

Radiation-induced skin injury remains a serious concern during radiotherapy. Cu/Zn-superoxide dismutase (Cu/Zn-SOD, SOD₁) is a conserved enzyme for scavenging superoxide radical in cells. Because of the integrity of cell membranes, exogenous molecule is not able to be incorporated into cells, which limited the application of natural SOD₁. The aim of this study was to evaluate the protective role of HIV-TAT protein transduction domain mediated protein transduction of SOD₁ (TAT-SOD₁) against ionizing radiation.

Methods

The recombinant TAT-SOD₁ and SOD₁ were obtained by prokaryotic–based protein expression system. The transduction effect and biological activity of TAT-SOD₁ was measured by immunofluorescence and antioxidant capability assays in human keratinocyte HaCaT cells. Mito-Tracker staining, reactive oxygen species (ROS) generation assay, cell apoptosis analysis and malondialdehyde (MDA) assay were used to access the protective effect of TAT- SOD₁.

Results

Uptake of TAT-SOD₁ by HaCaT cells retained its biological activity. Compared with natural SOD₁, the application of TAT-SOD₁ significantly enhanced the viability and decreased the apoptosis induced by X-ray irradiation. Moreover, TAT-SOD₁ reduced ROS and preserved mitochondrial integrity after radiation exposure in HaCaT cells. Radiation-induced γH2AX foci, which are representative of DNA double strand breaks, were decreased by pretreatment with TAT-SOD₁. Furthermore, subcutaneous application of TAT-SOD₁ resulted in a significant decrease in 45 Gy electron beam-induced ROS and MDA concentration in the skins of rats.

Conclusions

This study provides evidences for the protective role of TAT-SOD₁ in alleviating radiation-induced damage in HaCaT cells and rat skins, which suggests a new therapeutic strategy for radiation-induced skin injury.

Thymoquinone induces apoptosis in oral cancer cells through p38β inhibition

Oral cancer is a common malignancy associated with high morbidity and mortality. While p38 MAPK is reported to be involved in different cellular activities such as proliferation and differentiation, reports rarely define the roles of the individual members of the p38 MAPK family in cancer. We used two unique cell lines developed by our lab representing chemically induced oral cancer cells (T28) and non-tumor cells (N28) obtained from tissues surrounding the induced cancer as a model to screen out whether p38 MAPK is involved in the malignant transformation processes. The results suggest an association between p38β not p38α and oral cancer development. Additionally, the anti-cancer activity of thymoquinone (TQ) was screened out and we found evidences suggesting that the anti-tumor activity of TQ may be attributed to the downregulation of p38β MAPK.

A novel binuclear palladacycle complex inhibits melanoma growth in vitro and in vivo through apoptosis and autophagy

Malignant melanoma is an aggressive skin cancer and it is reported to be the most treatment-resistant human cancer. Here we describe the anti-tumour activity of a novel binuclear palladacycle complex (AJ-5) in vertical growth phase (ME1402) and metastatic (WM1158) melanoma cell lines. We show that compared to normal control cell lines, AJ-5 is more effective in inhibiting the proliferation of ME1402 and WM1158 melanoma cells with IC50 values of 0.19 and 0.20μM, respectively. Flow cytometry analyses showed that AJ-5 induced apoptosis (sub-G1 peak) which was confirmed by Annexin V-FITC/propidium iodide double-staining, nuclear fragmentation and an increase in the levels of PARP cleavage. Furthermore, AJ-5 was shown to induce both intrinsic and extrinsic apoptotic pathways as measured by PUMA, Bax and active caspases. Interestingly, AJ-5 treatment also simultaneously induced the formation of autophagosomes and led to an increase in the autophagy markers LC3II and Beclin1. Inhibition of autophagy reduced AJ-5 cytotoxicity suggesting that AJ-5 induced autophagy was a cell death and not cell survival mechanism. Moreover we show that AJ-5 induces the ATM-CHK2 DNA damage pathway and that its anti-tumour function is mediated by the p38 and ERK1/2 signalling pathways. Importantly, AJ-5 treatment efficiently reduced tumour growth in melanoma bearing mice and induced high levels of autophagy and apoptosis markers. Together these findings suggest that AJ-5 may be an effective chemotherapeutic drug in the treatment of melanoma, a highly aggressive and intractable cancer.

Salvianolic acid B induces apoptosis in human glioma U87 cells through p38-mediated ROS generation

Salvianolic acid B (SalB), the main water-soluble bioactive compounds isolated from the traditional Chinese medical herb Danshen, has been shown to exert anti-cancer effect in several cancer cell lines. The aim of our study was to investigate the potential anti-cancer effect of SalB in human glioma U87 cells. We found that treatment with SalB significantly decreased cell viability of U87 cells in a dose- and time-dependent manner. SalB also enhanced the intracellular ROS generation and induced apoptotic cell death in U87 cells. Western blot analysis suggested that SalB increased the phosphorylation of p38 MAPK and p53 in a dose-dependent manner. Moreover, blocking p38 activation by specific inhibitor SB203580 or p38 specific siRNA partly reversed the anti-proliferative and pro-apoptotic effects, and ROS production induced by SalB treatment. The anti-tumor activity of SalB in vivo was also demonstrated in U87 xenograft glioma model. All of these findings extended the anti-cancer effect of SalB in human glioma cell lines, and suggested that these inhibitory effects of SalB on U87 glioma cell growth might be associated with p38 activation mediated ROS generation. Thus, SalB might be concerned as an effective and safe natural anticancer agent for glioma prevention and treatment.

Signalling mechanisms involved in renal pathological changes during cisplatin-induced nephropathy

CONTEXT

Cisplatin, a coordination platinum complex, is used as a potential anti-neoplastic agent, having well recognized DNA-damaging property that triggers cell-cycle arrest and cell death in cancer therapy. Beneficial chemotherapeutic actions of cisplatin can be detrimental for kidneys.

BACKGROUND

Unbound cisplatin gets accumulated in renal tubular cells, leading to cell injury and death. This liable action of cisplatin on kidneys is mediated by altered intracellular signalling pathways such as mitogen-activated protein kinase (MAPK), extracellular regulated kinase (ERK), or C- Jun N terminal kinase/stress-activated protein kinase (JNK/SAPK). Further, these signalling alterations are responsible for release and activation of tumour necrosis factor (TNF-α), mitochondrial dysfunction, and apoptosis, which ultimately cause the renal pathogenic process. Cisplatin itself enhances the generation of reactive oxygen species (ROS) and activation of nuclear factor-κB (NF-κB), inflammation, and mitochondrial dysfunction, which further leads to renal apoptosis. Cisplatin-induced nephropathy is also mediated through the p53 and protein kinase-Cδ (PKCδ) signalling pathways.

OBJECTIVE

This review explores these signalling alterations and their possible role in the pathogenesis of cisplatin-induced renal injury.

Abrogation of the p38 MAPK α signaling pathway does not promote radioresistance but its activity is required for 5-Fluorouracil-associated radiosensitivity

The p38 Mitogen Activated Protein Kinase (MAPK) signaling pathway has become a major player in the response to DNA-damage. A growing body of evidences has been relating this signaling pathway to the cellular response to ionizing radiation (IR), suggesting a role in radioresistance. Here, we study the implication of this signaling pathway in the response to IR in terms of radioresistance. To this end we used 10 different cell lines derived from several types of tumors (colorectal, non-small cell lung cancer -NSCLC-, renal and glioblastoma). Although p38 MAPK is transiently activated by IR, our data, obtained by genetic and chemical approaches, showed that this signaling pathway is not implicated in cellular viability after IR exposure. Indeed, down-modulation of this signaling pathway promotes a mild radiosensitivity depending on the cell line. However, it is remarkable that lack of p38 MAPK α abrogates the radiosensitizing effect of 5-Fluorouracil (5-FU) in HCT116 cell line, supporting the role of this MAPK in the radiosensitizing action of 5-FU.

Alterations of phosphoproteins in NCI-H526 small cell lung cancer cells involved in cytotoxicity of cisplatin and titanocene Y

First-line treatment of small cell lung cancer (SCLC) with combination chemotherapy consisting of cis-diamminedichloroplatinum(II) (cisplatin) and etoposide is frequently followed by early relapses and a dismal prognosis. Survival of a fraction of tumor cells and development of chemoresistance may be influenced by an initial cellular stress response against the administered xenobiotics. Therefore, we compared the short-term effects of cisplatin and non-cross-resistant bis-[(p-methoxybenzyl)cyclopentadienyl] titanium(IV) dichloride (Titanocene Y) on phosphorylation of 46 sites of a total of 38 signaling proteins in tumor suppressor protein 53 (p53)-wild-type NCI-H526 SCLC cells. The functional significance of selected kinases for the cytotoxicity of both drugs was tested using specific inhibitors and an activator. The cisplatin-induced cellular stress response involved activation of p38α mitogen-activated protein kinase, whereas Titanocene Y-triggered signaling affected c-Jun N-terminal kinase. Phosphorylation of adenosine monophosphate (AMP)-activated protein kinase α1 (AMPKα1) was increased by both drugs, which promoted cell survival, as indicated by results obtained using AMPK inhibitor compound C and AMPK activator 5-aminoimidazole-4-carboxamide 1-β-d-ribofuranoside. This is in good agreement with previous reports, where AMPKα1 was demonstrated to represent an important factor for the sensitivity to cisplatin in colon and ovarian cancers, most likely by induction of autophagy. Thus, AMPKα1 constitutes a potential target to be exploited for chemotherapeutic treatment of SCLC to circumvent resistance to metal-based compounds.