Rosario Perona

Targeted Cargo Delivery in Senescent Cells Using Capped Mesoporous Silica Nanoparticles

Learning to let go with age: Intracellular controlled release of molecules within senescent cells was achieved using mesoporous silica nanoparticles (MSNs) capped with a galacto-oligosaccharide (GOS) to contain the cargo molecules (magenta spheres; see scheme). The GOS is a substrate of the senescent biomarker, senescence-associated β-galactosidase (SA-β-gal), and releases the cargo upon entry into SA-β-gal expressing cells.

DUSP1/MKP1 promotes angiogenesis, invasion and metastasis in non-small-cell lung cancer

DUSP1/MKP1 is a dual-specific phosphatase that regulates MAPKs activity, with an increasingly recognized role in tumor biology. To understand more about the involvement of DUSP1 in lung cancer, we performed gene expression analyses of parental and DUSP1-interfered H460 non-small-cell lung cancer (NSCLC) cells. Downregulation of DUSP1 induced changes in the expression levels of genes involved in specific biological pathways, including angiogenesis, MAP kinase phosphatase activity, cell–cell signaling, growth factor and tyrosine-kinase receptor activity. Changes in the expression of some of these genes were due to modulation of c-Jun-N-terminal kinase and/or p38 activity by DUSP1. Complementary functional assays were performed to focus on the implication of DUSP1 in angiogenesis and metastasis. In H460 cells, interference of DUSP1 resulted in a diminished capacity to invade through Matrigel, to grow tumors in nude mice and also to induce metastasis through tail-vein injection. Furthermore, the angiogenic potential of H460 cells was also impaired, correlating with a decrease in VEGFC production and indicating that DUSP1 could be required to induce angiogenesis. Finally, we studied whether a similar relationship occurred in patients. In human NSCLC specimens, DUSP1 was mainly expressed in those tumor cells close to CD31 vascular structures and a statistically significant correlation was found between VEGFC and DUSP1 expression. Overall, these results provide evidence for a role of DUSP1 in angiogenesis, invasion and metastasis in NSCLC.

Cancer stem cells and cisplatin-resistant cells isolated from non-small-lung cancer cell lines constitute related cell populations

Lung cancer is the top cause of cancer‐related deceases. One of the reasons is the development of resistance to the chemotherapy treatment. In particular, cancer stem cells (CSCs), can escape treatment and regenerate the bulk of the tumor. In this article, we describe a comparison between cancer cells resistant to cisplatin and CSCs, both derived from the non‐small‐cell lung cancer cell lines H460 and A549. Cisplatin‐resistant cells were obtained after a single treatment with the drug. CSCs were isolated by culture in defined media, under nonadherent conditions. The isolated CSCs were clonogenic, could be differentiated into adherent cells and were less sensitive to cisplatin than the original cells. Cisplatin resistant and CSCs were able to generate primary tumors and to metastasize when injected into immunodeficient Nu/Nu mice, although they formed smaller tumors with a larger latency than untreated cells. Notably, under appropriated proportions, CSCs synergized with differentiated cells to form larger tumors. CSCs also showed increased capacity to induce angiogenesis in Nu/Nu mice. Conversely, H460 cisplatin‐resistant cells showed increased tendency to develop bone metastasis. Gene expression analysis showed that several genes involved in tumor development and metastasis (EGR1, COX2, MALAT1, AKAP12, ADM) were similarly induced in CSC and cisplatin‐resistant H460 cells, in agreement with a close similarity between these two cell populations. Cells with the characteristic growth properties of CSCs were also isolated from surgical samples of 18 out of 44 lung cancer patients. A significant correlation (P = 0.028) was found between the absence of CSCs and cisplatin sensitivity.

Pyrazino[1,2-b]isoquinolines : Synthesis and study of their cytostatic and cytotoxic properties

The in vitro antitumor potential of novel pyrazino[1,2-b]-isoquinoline-4-ones that contain a half portion of significant natural products was explored in three cancer cell lines: MDA-MB 231 human breast carcinoma, A-549 human lung carcinoma, and HT-29 human colon carcinoma. In general, these compounds show mid to low muM GI(50)s, but LC(50)s over 100 microM with the exceptions of compounds 3b and 31 that are moderately toxic in all cell lines, while compound 4a is highly toxic and selective for HT-29 cells with LC(50) values in the high nanomolar range. Experiments directed to elucidate possible mechanisms of action with compounds 3a, 29, and 31 showed that compound 3a is able to efficiently induce apoptosis triggered directly from the G2/M phase of cell cycle, while compounds 29 and 31 are potentially cytostatic agents that induce the G1/S arrest of cell cycle. All three compounds do not act through DNA damage, since they do not activate this signaling at the level of sensors, transducers, and executers. Furthermore, the apoptosis induction of 3a is not mediated by activation of pro-apoptotic kinases JNK and p38 or by activation of AKT.

Mad2 and BubR1 modulates tumourigenesis and paclitaxel response in MKN45 gastric cancer cells

Aneuploidy and chromosomal instability (CIN) are common features of gastric cancer (GC), but their contribution to carcinogenesis and antitumour therapy response is still poorly understood. Failures in the mitotic checkpoint induced by changes in expression levels of the spindle assembly checkpoint (SAC) proteins cause the missegregation of chromosomes in mitosis as well as aneuploidy. To evaluate the possible contribution of SAC to GC, we analyzed the expression levels of proteins of the mitotic checkpoint complex in a cohort of GC cell lines. We found that the central SAC proteins, Mad2 and BubR1, were the more prominently expressed members in disseminated GC cell lines. Silencing of Mad2 and BubR1 in MKN45 and ST2957 cells decreased their cell proliferation, migration and invasion abilities, indicating that Mad2 and BubR1 could contribute to cellular transformation and tumor progression in GC. We next evaluated whether silencing of SAC proteins could affect the response to microtubule poisons. We discovered that paclitaxel treatment increased cell survival in MKN45 cells interfered for Mad2 or BubR1 expression. However, apoptosis (assessed by caspase-3 activation, PARP proteolysis and levels of antiapoptotic Bcl 2-family members), the DNA damage response (assessed by H2Ax phosphorylation) and exit from mitosis (assessed by Cyclin B degradation and Cdk1 regulation) were activated equally between cells, independently of Mad2 or BubR1-protein levels. In contrast, we observed that the silencing of Mad2 or BubR1 in MKN45 cells showed the induction of a senescence-like phenotype accompanied by cell enlargement, increased senescence-associated β-galactosidase activity and increased IL-6 and IL-8 expression. In addition, the senescent phenotype is highly increased after treatment with PTX, indicating that senescence could prevent tumorigenesis in GC. In conclusion, the results presented here suggest that Mad2 and BubR1 could be used as prognostic markers of tumor progression and new pharmacological targets in the treatment for GC.

Molecular biology of malignant gliomas

Gliomas are the most common primary brain tumours. In keeping with the degree of aggressiveness, gliomas are divided into four grades, with different biological behaviour. Furthermore, as different gliomas share a predominant histological appearance, the final classification includes both, histological features and degree of malignancy. For example, gliomas of astrocytic origin (astrocytomas) are classified into pilocytic astrocytoma (grade I), astrocytoma (grade II), anaplastic astrocytoma (grade III) and glioblastoma multiforme (GMB) (grade IV). Tumors derived from oligodendrocytes include grade II (oliogodendrogliomas) and grade III neoplasms (oligoastrocytoma). Each subtype has a specific prognosis that dictates the clinical management. In this regard, a patient diagnosed with an oligodendroglioma totally removed has 10-15 years of potential survival. On the opposite site, patients carrying a glioblastoma multiforme usually die within the first year after the diagnosis is made. Therefore, different approaches are needed in each case. Obviously, prognosis and biological behaviour of malignant gliomas are closely related and supported by the different molecular background that possesses each type of glioma. Furthermore, the ability that allows several low-grade gliomas to progress into more aggressive tumors has allowed cancer researchers to elucidate several pathways implicated in molecular biology of these devastating tumors. In this review, we describe classical pathways involved in human malignant gliomas with special focus with recent advances, such as glioma stem-like cells and expression patterns from microarray studies.

MKP1 repression is required for the chemosensitizing effects of NF-κB and PI3K inhibitors to cisplatin in non-small cell lung cancer

Treatment of non-small cell lung cancer (NSCLC) with cisplatin has a level of antitumor activity still modest. We have shown previously that MKP1/DUSP1 inhibits cisplatin-induced apoptosis in NSCLC cells and is overexpressed in tumors from most patients with stage I-II NSCLC. Here, using different NSCLC cell lines we found that MKP1 and NF-kappaB are differentially expressed. We studied whether targeting MKP1, NF-kappaB or both affects cisplatin-induced cell death. MKP1 is expressed in H460 and H727 cells. H727 and H1299 cells showed constitutive phosphorylation of Akt and increased NF-kappaB activity than did H460 cells. H460-MKP1-siRNA-expressing cells (but not H727-MKP1-siRNA or H1299-MKP1-siRNA cells) exhibit a marked increase in cisplatin response compared with parental cells. Treatment with the PI3K inhibitor LY294002 or the NF-kappaB inhibitor BAY11-7082 enhanced cisplatin antitumor activity in parental H1299 cells but only weakly affected responses of H727 and H460 cells. MKP1-siRNA expression enhanced the chemosensitization effect of LY294002 and BAY11-7082 on H727 and H460 cells. Additionally, NSCLC cell lines with higher NF-kappaB-constitutive activation were the most sensitive to PS-341 (Bortezomib), a non-specific NF-kappaB inhibitor. This finding suggests the proteasome as a suitable strategy in treating NSCLC tumors with high constitutive NF-kappaB activity. Altogether, these results showed that either an activated PI3K/Akt/NF-kappaB pathway and/or high MKP1 was linked to reduced sensitivity to cisplatin in NSCLC cells. Inhibition of NF-kappaB or PI3K potently enhanced cisplatin cytotoxicity in cells with endogenous or genetically induced low MKP1 levels. These findings support the potential improvement in cisplatin responses by co-targeting NF-kappaB or Akt and MKP1.

Development of surface modified biodegradable polymeric nanoparticles to deliver GSE24.2 peptide to cells: A promising approach for the treatment of defective telomerase disorders

The aim of the present study was to develop a novel strategy to deliver intracellularly the peptide GSE24.2 for the treatment of Dyskeratosis congenita (DC) and other defective telomerase disorders. For this purpose, biodegradable polymeric nanoparticles using poly(lactic-co-glycolic acid) (PLGA NPs) or poly(lactic-co-glycolic acid)-poly ethylene glycol (PLGA-PEG NPs) attached to either polycations or cell-penetrating peptides (CPPs) were prepared in order to increase their cellular uptake. The particles exhibited an adequate size and zeta potential, with good peptide loading and a biphasic pattern obtained in the in vitro release assay, showing an initial burst release and a later sustained release. GSE24.2 structural integrity after encapsulation was assessed using SDS-PAGE, revealing an unaltered peptide after the NPs elaboration. According to the cytotoxicity results, cell viability was not affected by uncoated polymeric NPs, but the incorporation of surface modifiers slightly decreased the viability of cells. The intracellular uptake exhibited a remarkable improvement of the internalization, when the NPs were conjugated to the CPPs. Finally, the bioactivity, addressed by measuring DNA damage rescue and telomerase reactivation, showed that some formulations had the lowest cytotoxicity and highest biological activity. These results proved that GSE24.2-loaded NPs could be delivered to cells, and therefore, become an effective approach for the treatment of DC and other defective telomerase syndromes.

CHK1 expression in Gastric Cancer is modulated by p53 and RB1/E2F1: implications in chemo/radiotherapy response.

Radiation has a limited but relevant role in the adjuvant therapy of gastric cancer (GC) patients. Since Chk1 plays a critical function in cellular response to genotoxic agents, we aimed to analyze the role of Chk1 in GC as a biomarker for radiotherapy resistance. We analyzed Chk1 expression in AGS and MKN45 human GC cell lines by RT-QPCR and WB and in a small cohort of human patient’s samples. We demonstrated that Chk1 overexpression specifically increases resistance to radiation in GC cells. Accordingly, abrogation of Chk1 activity with UCN-01 and its expression with shChk1 increased sensitivity to bleomycin and radiation. Furthermore, when we assessed Chk1 expression in human samples, we found a correlation between nuclear Chk1 accumulation and a decrease in progression free survival. Moreover, using a luciferase assay we found that Chk1’s expression is controlled by p53 and RB/E2F1 at the transcriptional level. Additionally, we present preliminary data suggesting a posttranscriptional regulation mechanism, involving miR-195 and miR-503, which are inversely correlated with expression of Chk1 in radioresistant cells. In conclusion, Chk1/microRNA axis is involved in resistance to radiation in GC, and suggests Chk1 as a potential tool for optimal stratification of patients susceptible to receive adjuvant radiotherapy after surgery.

p53 pathway activation by telomere attrition in X-DC primary fibroblasts occurs in the absence of ribosome biogenesis failure and as a consequence of DNA damage

BackgroundDyskeratosis congenita (DC) is a rare inherited bone marrow failure syndrome with high clinical heterogeneity. Various mutations have been reported in DC patients, affecting genes that code for components of H/ACA ribonucleoproteins, proteins of the telomerase complex and components of the shelterin complex.ObjectivesWe aim to clarify the role of ribosome biogenesis failure in senescence induction in X-DC since some studies in animal models have reported a decrease in ribosome biogenesis as a major role in the disease.MethodsDyskerin was depleted in normal human fibroblasts by expressing two DKC1 shRNAs. Common changes in gene expression profile between these dyskerin-depleted cells and X-DC fibroblasts were analyzed.ResultsDyskerin depletion induced early activation of the p53 pathway probably secondary to ribosome biogenesis failure. However, the p53 pathway in the fibroblasts from X-DC patients was activated only after an equivalent number of passes to AD-DC fibroblasts, in which telomere attrition in each division rendered shorter telomeres than control fibroblasts. Indeed, no induction of DNA damage was observed in dyskerin-depleted fibroblasts in contrast to X-DC or AD-DC fibroblasts suggesting that DNA damage induced by telomere attrition is responsible for p53 activation in X-DC and AD-DC fibroblasts. Moreover, p53 depletion in senescent DC fibroblasts rescued their proliferative capacity and reverted the morphological changes produced after prolonged culture.ConclusionsOur data indicate that ribosome biogenesis do not seem to play an important role in dyskeratosis congenita, conversely increasing DNA damage and activation of p53 pathway triggered by telomere shortening is the main activator of cell senescence.