Role of the p53/p21 system in the response of human colon carcinoma cells to Doxorubicin

BACKGROUND: Colon adenocarcinomas are refractory to a number of widely used anticancer agents. Multifactorial mechanisms have been implicated in this intrinsically resistant phenotype, including deregulation of cell death pathways. In this regard, the p53 protein has a well established role in the control of tumor cell response to DNA damaging agents; however, the relationship between p53-driven genes and drug sensitivity remains controversial. The present study investigates the role of the p53/p21 system in the response of human colon carcinoma cells to treatment with the cytotoxic agent doxorubicin (DOX) and the possibility to modify the therapeutic index of DOX by modulation of p53 and/or p21 protein levels. METHODS: The relationship between p53 and p21 protein levels and the cytotoxic effect of DOX was investigated, by MTT assay and western blot analysis, in HCT116 (p53-positive) and HT29 (p53-negative) colon cancer cells. We then assessed the effects of DOX in two isogenic cell lines derived from HCT116 by abrogating the expression and/or function of p53 and p21 (HCT116-E6 and HCT116 p21-/-, respectively). Finally, we evaluated the effect of pre-treatment with the piperidine nitroxide Tempol (TPL), an agent that was reported to induce p21 expression irrespective of p53 status, on the cytotoxicity of DOX in the four cell lines. Comparisons of IC50 values and apoptotic cell percentages were performed by ANOVA and Bonferroni's test for independent samples. C.I. calculations were performed by the combination Index method. RESULTS: Our results indicate that, in the colon carcinoma cell lines tested, sensitivity to DOX is associated with p21 upregulation upon drug exposure, and DOX cytotoxicity is potentiated by pre-treatment with TPL, but only in those cell lines in which p21 can be upregulated. CONCLUSIONS: p21 induction may significantly contribute to the response of colon adenocarcinomas cells to DOX treatment; and small molecules that can exploit p53-independent pathways for p21 induction, such as TPL, may find a place in chemotherapeutic protocols for the clinical management of colorectal cancer, where p53 function is often lost, due to genetic or epigenetic defects or to post-transcriptional inactivating mechanisms

The igfr1 inhibitor nvp-aew541 disrupts a pro-survival and pro-angiogenic igf-stat3-hif1 pathway in human glioblastoma cells

International audienceInappropriate activation of the IGF (insulin-like growth factor) system has been implicated in the growth and progression of a number of tumor types. Recent evidence indicates a possible role for the IGF system in modulating/mediating tumor cell response to hypoxia, a common occurrence in solid tumors, and particularly in malignant gliomas, causing tumor cells either to die, or to mount a pleiotropic adaptive response that is mainly orchestrated through activation of the hypoxia-inducible transcription factor HIF1. Experimental evidence suggests possible links between IGF- and HIF1-dependent signaling pathways, as well as a role for activated STAT3 in mediating their activities. Interestingly, is among the target genes transactivated by HIF1, thereby providing the missing link in a hypothetical autocrine self-amplifying circuit

Percentage of apoptotic cells in HCT116, HT29, HCT116 E6 and HCT116 p21-/- cells before and after 1 h exposure to DOX followed by 23 h incubation in drug-free medium (white bars: untreated; light grey bars: DOX 1 μM; dark grey bars: DOX 10 μM)

<p><b>Copyright information:</b></p><p>Taken from "Role of the p53/p21 system in the response of human colon carcinoma cells to Doxorubicin"</p><p>BMC Cancer 2004;4():92-92.</p><p>Published online 15 Dec 2004</p><p>PMCID:PMC544559.</p><p>Copyright © 2004 Ravizza et al; licensee BioMed Central Ltd.</p> Mean ± s.e.m. of 3 independent experiments

Dose-response curves of HCT116 (■), HT29 (▲), HCT116E6 (▼), and HCT116 p21-/- (●) cells after 1 hour exposure to DOX followed by 72 h incubation in drug free medium (mean ± s

<p><b>Copyright information:</b></p><p>Taken from "Role of the p53/p21 system in the response of human colon carcinoma cells to Doxorubicin"</p><p>BMC Cancer 2004;4():92-92.</p><p>Published online 15 Dec 2004</p><p>PMCID:PMC544559.</p><p>Copyright © 2004 Ravizza et al; licensee BioMed Central Ltd.</p>e.m. of 4–6 experiments)

Phototoxicity of two positive-charged diaryl porphyrins in multicellular tumor spheroids

Photodynamic therapy (PDT) is a clinically approved cancer treatment in which reactive oxygen species are formed only when three harmless components, a photosensitizer (PS), light and molecular oxygen, are present at the same time, leading to cell death. Most of the PSs were tested on monolayer cells, but differences between 2D cells and solid tumors significantly limit the value of in vitro PDT studies, whereas the use of 3D spheroid might be more suitable for drug development and preclinical drug testing for PDT. In a previous work we have shown that two positive-charged diaryl porphyrins (2 and 4) were more potent than the corresponding neutral molecules (1 and 3) on a panel of 2D-cultured cancer cell lines. In the present study the photodynamic effects of these molecules have been evaluated on HCT116 and MCF7 spheroids. In-duction of apoptotic and necrotic cell death, and generation of reactive oxygen species (ROS) have been also evaluated, along with accumulation and localization of PSs into spheroids. Our findings indicate that 2 and 4 retained their phototoxic effects also in 3D spheroids; furthermore, they were more potent than 1 and 3 and as potent as Foscan (m-THPC), the most successful PS approved for clinical PDT of cancer, used as reference. Although further aspects of their mechanisms of action need to be addressed, our results strongly suggest a potential in vivo photodynamic application of 2 and 4, considering that spheroids represent a more realistic indicator of in vivo therapeutic efficacy than 2D cell lines

In Vivo Effects of A Pro-PO System Inhibitor on the Phagocytosis of Xenorhabdus Nematophila in Galleria Mellonella Larvae

Xenorhabdus nematophila is a Gram-negative bacterium symbiont of the entomopathogen nematode Steinernema carpocapsae whose immunosuppressive properties over host\u2019s immune response have been thoroughly investigated. In particular, live X. nematophila actively impairs phagocytosis in host\u2019s hemocytes through the secretion of inhibitors of eicosanoids synthesis. In this article we have investigated the cell surface structural features of X. nematophila responsible for the elusion from phagocytosis. To this end we have studied the uptake of heat-killed (hk), fluorescein isothiocyanate (FITC)-labeled X. nematophila by phagocytes from both a host insect and a mammalian species. In vitro dead X. nematophila passively resists engulfment by insect hemocytes without impairing the phagocytosis machinery whereas, unexpectedly, in vivo a significant phagocytosis of dead X. nematophila was observed. X. nematophila in vivo phagocytosis was increased by the co-injection of the specific inhibitor of pro-phenoloxidase (PO) system phenylthiourea (PTU), even if these effects were not observed in in vitro tests. Furthermore, biochemical modifications of X. nematophila cell wall implement in vivo phagocytosis, suggesting that this bacterium avoid phagocytosis because the ligand of phagocytic receptors is somehow buried or disguised in the cell wall. Finally, dead X. nematophila escapes engulfment even by human phagocytes suggesting that X. nematophila could be a useful model to investigate escape from phagocytosis by mammalian macrophages

New BODIPYs for photodynamic therapy (PDT): Synthesis and activity on human cancer cell lines

A new class of compounds based on the 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene core, known as BODIPYs, has attracted significant attention as photosensitizers suitable for application in photodynamic therapy (PDT), which is a minimally invasive procedure to treat cancer. In PDT the combination of a photosensitizer (PS), light, and oxygen leads to a series of photochemical reactions generating reactive oxygen species (ROS) exerting cytotoxic action on tumor cells. Here we present the synthesis and the study of the in vitro photodynamic effects of two BODIPYs which differ in the structure of the substituent placed on the meso (or 8) position of the dipyrrolylmethenic nucleus. The two compounds were tested on three human cancer cell lines of different origin and degree of malignancy. Our results indicate that the BODIPYs are very effective in reducing the growth/viability of HCT116, SKOV3 and MCF7 cells when irradiated with a green LED source, whereas they are practically devoid of activity in the dark. Phototoxicity occurs mainly through apoptotic cell death, however necrotic cell death also seems to play a role. Furthermore, singlet oxygen generation and induction of the increase of reactive oxygen species also appear to be involved in the photodynamic effect of the BODIPYs. Finally, it is worth noting that the two BODIPYs are also able to exert anti-migratory activity

Vitamin D Deficiency has a Negative Impact on Cetuximab-Mediated Cellular Cytotoxicity against Human Colon Carcinoma Cells

Low vitamin D plasma levels are associated with an adverse prognosis in colon cancer patients, which might be explained in part by the effects of the vitamin on the immune system. Antibody-dependent cell-mediated cytotoxicity (ADCC) significantly contributes to the anti-tumor effect of monoclonal antibodies, in particular cetuximab, a growth factor receptor (EGFR)-targeted chimeric antibody that is frequently added to chemotherapy in the treatment of colon cancer. The present study evaluates the association between vitamin D plasma levels and the ability of ex-vivo NK cells to support cetuximab-mediated ADCC in colon cancer cell lines. Blood samples were obtained from 124 healthy volunteers and vitamin D plasma levels were determined by RIA. NK cells isolated from 101 blood samples were added to HT29 human colorectal carcinoma cells with or and without cetuximab, and ADCC was assessed using a colorimetric lactate dehydrogenase assay. Correlation analysis indicates a significant association between vitamin D plasma level and cetuximab-induced ADCC, that is unaffected by gender or age; subject stratification by vitamin D levels indicates that NK cells from samples with vitamin D &lt; 20 ng/mL are significantly less efficient in inducing ADCC. NK cells from the remaining 23 samples were used in a smaller, confirmatory study in two additional colon cancer cell lines; a significant correlation between vitamin D and NK-mediated ADCC was observed in both cases. These data suggest that vitamin D testing in patients with advanced colorectal cancer in therapy with cetuximab and subsequent supplementation for deficient/insufficient patients, could improve cetuximab induced ADCC.Background: Hypovitaminosis D is associated with an adverse prognosis in colon cancer patients, possibly due to the effects of the vitamin on the immune system. Antibody-dependent cell-mediated cytotoxicity (ADCC) significantly contributes to the anti-tumor effects of monoclonal antibodies, including cetuximab, an epidermal growth factor receptor (EGFR)-targeted monoclonal antibody that is frequently added to chemotherapy in the treatment of colon cancer. Objective: The present study evaluates the association between vitamin D serum levels and the ability of ex vivo NK cells to support cetuximab-mediated ADCC in colon cancer cell lines. Methods: Blood samples were obtained from 124 healthy volunteers and serum vitamin D was determined by RIA. NK cells were isolated from each sample and added to human colorectal carcinoma cells with or without cetuximab, and ADCC was assessed using a colorimetric lactate dehydrogenase assay. Results: Correlation analysis indicates a significant, gender- and age-independent association between vitamin D levels and cetuximab-induced ADCC on HT29 cells, where NK cells from samples with vitamin D &lt; 20&nbsp;ng/mL are significantly less efficient in inducing ADCC. A confirmatory study on two additional colon cancer cell lines yielded similar results. Conclusions: These data suggest that vitamin D supplementation in vitamin-deficient/insufficient colorectal cancer patients could improve cetuximab-induced ADCC

Ruthenium(II)-Arene Curcuminoid Complexes as Photosensitizer Agents for Antineoplastic and Antimicrobial Photodynamic Therapy: In Vitro and In Vivo Insights

Photodynamic therapy (PDT) is an anticancer/antibacterial strategy in which photosensitizers (PSs), light, and molecular oxygen generate reactive oxygen species and induce cell death. PDT presents greater selectivity towards tumor cells than conventional chemotherapy; however, PSs have limitations that have prompted the search for new molecules featuring more favorable chemical–physical characteristics. Curcumin and its derivatives have been used in PDT. However, low water solubility, rapid metabolism, interference with other drugs, and low stability limit curcumin use. Chemical modifications have been proposed to improve curcumin activity, and metal-based PSs, especially ruthenium(II) complexes, have attracted considerable attention. This study aimed to characterize six Ru(II)-arene curcuminoids for anticancer and/or antibacterial PDT. The hydrophilicity, photodegradation rates, and singlet oxygen generation of the compounds were evaluated. The photodynamic effects on human colorectal cancer cell lines were also assessed, along with the ability of the compounds to induce ROS production, apoptotic, necrotic, and/or autophagic cell death. Overall, our encouraging results indicate that the Ru(II)-arene curcuminoid derivatives are worthy of further investigation and could represent an interesting option for cancer PDT. Additionally, the lack of significant in vivo toxicity on the larvae of Galleria mellonella is an important finding. Finally, the photoantimicrobial activity of HCurc I against Gram-positive bacteria is indeed promising