PubMed Health⌕ Search

Biomedical subjects

C G Ferreira

Publications and source records attributed to C G Ferreira.

8 recordsLinked to original sources
PubMed2003

Thymidylate synthase inhibition triggers apoptosis via caspases-8 and -9 in both wild-type and mutant p53 colon cancer cell lines.

Thymidylate synthase (TS) is an important target for chemotherapy and increased levels are associated with resistance to colorectal cancer chemotherapy. TS can be inhibited by 5-fluorouracil (5-FU) and antifolates, ultimately resulting in apoptosis. We aimed to clarify whether activation of caspases and Fas signalling are crucial for the onset of apoptosis after specific inhibition of TS and whether p53 plays a role in activation of these downstream processes. For this purpose, wild-type (wt) and mutant (mt) p53 colon cancer cell lines, Lovo and WiDr, respectively, transfected with mt- and wt-p53, were treated with the specific TS inhibitor, AG337. Treatment with 10xIC(50) values of AG337 for 48 h resulted in S phase arrest in all Lovo and WiDr cells (up to 50% of cells being in S phase), irrespective of their p53 status. After 72 h, the induction of apoptosis was most pronounced in the AG337-sensitive cells. Approximately 30% apoptosis was detected in all of the WiDr cells, 20% in Lovo li (non-functional p53), 12-14% in Lovo 92 and B2 (wt p53) and only 7% in Lovo 175x2 cells (mt p53 transfected). The induction of apoptosis in Lovo cells, as determined using the classical sub-G1 peak after propidium iodide (PI) staining, was associated with an increase in the expression of Fas receptor. In addition, synergistic increases in apoptosis from approximately 10 to 35% after 48 h could be detected after simultaneous treatment of AG337 and the Fas activator antibody, CH11. Only additive effects were measurable in WiDr cells, without an increase in Fas receptor expression. Surprisingly, the Fas inhibitor, ZB4, could not decrease the amount of cell death in both cell lines after AG337 treatment. In contrast, simultaneous exposure of Lovo and WiDr cells to AG337 and inhibitors of caspases 8, 9 and 3 caused a decrease in the number of apoptotic cells compared with AG337 exposure alone. Inhibition of apoptosis by approximately 10-80% in Lovo and approximately 70-80% in WiDr cells could be detected. In conclusion, these results indicate that apoptosis induced after specific inhibition of TS is mediated via the caspases, but without clear involvement of Fas signalling. The status of p53 did not affect the onset of apoptosis by these caspases.

Apoptosis↗
PubMed2001

Assessment of IAP (inhibitor of apoptosis) proteins as predictors of response to chemotherapy in advanced non-small-cell lung cancer patients.

BACKGROUND: Expression of inhibitor of apoptosis family proteins (IAPs) has been shown in vitro to decrease chemosensitivity through caspase inhibition. However, the role of IAPs as predictors of response to chemotherapy in cancer patients remains to be determined. PATIENTS AND METHODS: Using immunohistochemistry, we assessed the expression of the IAP proteins c-IAP1, c-IAP2, and XIAP on tumors from 55 patients with advanced non-small-cell lung cancer (NSCLC) treated with chemotherapy, and correlated that with the observed response to chemotherapy, time to progression and overall survival. RESULTS: Differences were observed in the pattern of staining among the IAP proteins. The expression of c-IAP2 and XIAP was exclusively cytoplasmic. whereas c-IAP1 also displayed nuclear staining. The median expression of tumor cells for c-IAP1, c-IAP2, and XIAP was 70%, 45%, and 25%, respectively, and a correlation was observed between c-IAP1 and c-IAP2 (P = 0.004), and c-IAP1 and XIAP expression (P = 0.013). However, no association was seen between the expression of these proteins and sex, age, tumor size, stage, histology and grade of differentiation. Interestingly, expression of c-IAP1, c-IAP2, and XIAP did not predict response to chemotherapy. In addition, the expression of IAPs had no impact on the time to progression or overall survival of this group of patients. CONCLUSIONS: Our results indicate that: 1) there are differences in the level of expression and in the subcellular distribution of c-IAP1, c-IAP2, and XIAP in tumors derived from NSCLC patients. 2) The expression of c-IAP1, c-IAP2 and XIAP does not predict the response to chemotherapy in patients with advanced NSCLC. 3) The relation between expression of IAPs and chemosensitivity in cancer patients may be more complex than anticipated by in vitro data.

Adult↗
PubMed2001

Expression of X-linked inhibitor of apoptosis as a novel prognostic marker in radically resected non-small cell lung cancer patients.

PURPOSE: To assess the pattern of expression and the prognostic value of the inhibitor of apoptosis family member X-linked inhibitor of apoptosis (XIAP; MIHA/ILP-a) in radically resected non-small cell lung cancer patients. EXPERIMENTAL DESIGN: The expression of XIAP and its relationship with overall survival was analyzed by immunohistochemistry on tumors from 144 patients with early-stage non-small cell lung cancer. In addition, the apoptotic and mitotic index, Ki-67, p53, and bcl-2 levels were also assessed. RESULTS: XIAP expression was specific for tumor cells, and the pattern was cytoplasmic. The median expression of XIAP was 20%, and when this value was used as a cutoff point for statistical analyses, 63 of the samples were considered high XIAP-expressing and 81 low XIAP-expressing. Surprisingly, high XIAP-expressing patients had a longer overall survival than the group expressing lower levels (60 versus 24 months of median survival; log rank, P = 0.01). The positive impact of XIAP expression on survival was confirmed by multivariate analysis (P = 0.026). Although no correlation was observed between XIAP expression and the apoptotic index, a significant inverse correlation was observed between XIAP, Ki-67 (P = 0.006), and mitotic index (P = 0.04). CONCLUSIONS: The unexpected inverse correlation of XIAP with proliferation markers and the absence of correlation with apoptotic index, coupled with its role as an independent positive prognostic factor for survival in radically resected NSCLC patients imply a more complex role for XIAP in tumor biology than anticipated by in vitro data.

Aged↗
PubMed2000

Chemotherapy triggers apoptosis in a caspase-8-dependent and mitochondria-controlled manner in the non-small cell lung cancer cell line NCI-H460.

Chemotherapy-induced apoptosis is generally thought to be dependent on a pathway headed by caspase-9. This model is primarily based on studies performed in leukemia cells; however, little is known about caspase cascades in relatively resistant solid tumor cells, including non-small cell lung cancer (NSCLC) cells. Using the NSCLC cell line NCI-H460 (H460), here, we studied the effect of stable expression of various caspase inhibitors on apoptosis induced by the anticancer drugs cisplatin, topotecan, and gemcitabine. Interestingly, overexpression of caspase-9S and X-linked inhibitor of apoptosis (XIAP), both able to inhibit caspase-9 activity, failed to block apoptosis. In contrast, stable expression of caspase-8 inhibitors, such as cytokine response modifier A (CrmA) and dominant-negative caspase-8, almost completely abrogated apoptosis and also enhanced clonogenic survival. Caspase-8 activation in H460 cells was not mediated by death receptors, inasmuch as overexpression of dominant-negative Fas-associated death domain (FADD-DN) did not prevent procaspase-8 cleavage and subsequent apoptosis. However, stable expression of Bcl-2 and Bcl-xL did suppress these apoptotic events, including the release of cytochrome c from mitochondria, which was observed in drug-treated H460 cells. In the NSCLC cell line H460, we, thus, provide evidence for the existence of a novel drug-inducible apoptotic pathway in which activation of caspase-8, and not of caspase-9, forms the apical and mitochondria-dependent step that subsequently activates the downstream caspases.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Drug-induced apoptosis in lung cnacer cells is not mediated by the Fas/FasL (CD95/APO1) signaling pathway.

Anticancer drugs exert at least part of their cytotoxic effect by triggering apoptosis. We previously identified chemotherapy-induced apoptosis in lung cancer cells and suggested a role for p53 alternative or complementary pathways in this process. Recently, a role for the Fas/FasL (CD95/Apo1) signaling system in chemotherapy-induced apoptosis was proposed in some cell types. In the present work, the involvement of the Fas/FasL system in drug-induced apoptosis in lung cancer cells was investigated upon exposure to four cytotoxic drugs (cisplatin, gemcitabine, topotecan, and paclitaxel). We assessed the expression of Fas and FasL and the function of the Fas pathway in six lung cancer cell lines (H460, H322, GLC4, GLC4/ADR, H187, and N417). All lung cancer cell lines expressed Fas and FasL at RNA and protein levels, and apoptosis could be induced in four of six cell lines upon exposure to the Fas agonistic monoclonal antibody (mAb) CLB-CD95/15. Nevertheless, after drug exposure, no significant FasL up-regulation was observed, whereas the Fas expression was increased in the wild-type p53 cell line H460, but not in the other lines, proved to be mutant p53 by direct gene sequencing. Moreover, no correlation was observed in lung cancer cell lines between sensitivity to drugs and to a Fas agonistic mAb, and preincubation of cells with either the Fas-antagonistic mAb CLB-CD95/2 or a FasL-neutralizing mAb did not protect from drug-induced apoptosis. Taken together, these observations strongly argue against a role of the Fas/FasL signaling pathway in drug-induced apoptosis in lung cancer cells. Interestingly, caspase-8 activation was observed upon drug exposure, independently from Fas/FasL signaling.

Antineoplastic Agents↗
PubMed1999

Cell cycle disturbances and apoptosis induced by topotecan and gemcitabine on human lung cancer cell lines.

Apoptosis is a major mode of cell death in response to cytotoxic drug treatment. A correlation between induction of apoptosis and chemosensitivity has been documented in some preclinical models. Topotecan (a topoisomerase I inhibitor) and gemcitabine (a deoxycytidine analogue), two active new drugs for the treatment of lung cancer, were evaluated for their growth inhibitory effect on human lung cancer cell lines and their effect on cell cycle perturbation, apoptosis and apoptosis-related genes. The cytotoxicities of topotecan and gemcitabine on the human lung cancer cell lines H460 (wild-type-p53) and H322 (mutant p53 were determined after 72 h drug exposure employing the MTT assay. The apoptotic index (AI) was assessed by three methods: analysis of morphological changes using May-Grünwald-Giemsa (MGG) staining, the TUNEL assay and FACS analysis. Cell cycle disturbances were studied by FACS and the number of cells expressing p53 and p21 were determined by immunohistochemistry. Both gemcitabine and topotecan had potent growth inhibitory effects in human lung cancer cell lines; combination treatment with these two drugs showed some additivity but no synergism. Induction of apoptosis after treatment was concentration- and time-dependent with both drugs and IC80 concentrations induced the highest values. The DNA histograms at 4, 24, 48 and 72 h indicate that topotecan at IC80 concentrations causes accumulation of cells in S and G2/M phases, whereas gemcitabine at IC80 concentrations causes, accumulation of cells in G1 phase. Both compounds induced p53 and p21 expression in the H460 cell line but not in the H322 cell line; the percentage of cells expressing p53 was highest at IC80 values, whereas the highest percentage of p21 positive cells could be induced with IC50 values. This could suggest that p53 induces cell cycle arrest at low drug concentrations, whereas p53 induces apoptosis at higher concentrations. In conclusion, p53-dependent and independent pathways of apoptosis exist in lung cancer cell lines. Activation of the p53 pathway depends on the induced cellular damage. Understanding the cell cycle disturbances induced by these drugs may help in the design of more rational treatment schedules.

Antineoplastic Agents↗
PubMed1999

p53 and chemosensitivity.

BACKGROUND: Although hematologic malignancies and some solid tumors such as germ cell tumors and pediatric malignancies can be cured by cytotoxic treatment, the most prevalent solid tumors are relatively resistant to these interventions. Apoptosis is involved in the cell kill of anticancer drugs and p53 is believed to be of principal importance in this process. However p53 also plays a role in cell cycle arrest and DNA repair, cellular processes that can decrease the sensitivity to chemotherapy. Therefore, p53 may play a dual role after exposure to cytotoxic treatment, activating either mechanisms that lead to apoptosis or launching processes directing to DNA repair and survival of the cell. DESIGN: In this article, we review in details the p53 functions involved in the mediation of chemosensitivity. The preclinical and clinical data published in the recent years about the relation between p53 and chemosensitivity are discussed and the potential pitfalls associated to most of these studies, and that may account for the contradictory results produced so far are also mentioned.

Apoptosis↗