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P Perego

Publications and source records attributed to P Perego.

At least 55 records · Page 3Linked to original sources
PubMed1998

Sensitivity to cisplatin and platinum-containing compounds of Schizosaccharomyces pombe rad mutants.

The role of genes that affect response to radiation in determining sensitivity to platinum-containing compounds was studied using a panel of 23 strains of the yeast Schizosaccharomyces pombe. The radiation-hypersensitive mutants all had the same genetic background and most of them contained mutations that disabled either cell cycle checkpoints or DNA repair. The tested platinum compounds included cisplatin and two complexes containing diaminocyclohexane (oxaliplatin and tetraplatin), two ammine/cyclohexylamine complexes with different orientation of the leaving groups (JM216 and JM335) and a multinuclear platinum complex (BBR 3464). The cytotoxic effect of the selected platinum complexes was evaluated by using a microtiter growth inhibition assay with a 48 hr exposure to drug. The mutants fell into three groups with respect to sensitivity to cisplatin: four mutants (rad2, -7, -11, -15) exhibited minimal change in sensitivity; fifteen mutants (rad4-6, -8-10, -12-14, -16-17, -19-21, and -22) were 5.1-21.7-fold hypersensitive; only rad1 and -3 mutants, defective in checkpoints, and rad18, defective in repair, displayed a marked hypersensitivity. None of the mutants demonstrated appreciable change in sensitivity to JM216 presumably as a consequence of a lack of resistance of the wild-type strain, whereas a moderate increase in sensitivity to JM335 was observed for most of the mutants, and hypersensitivity to BBR3464 was observed only in rad1 and -3. No relevant changes in sensitivity to tetraplatin were observed. Most of the mutants, with the exception of rad2, -7, and -15, were hypersensitive to oxaliplatin. These findings demonstrate that specific mutations have disparate effects on the profile of sensitivity to different members of the same class of cytotoxic agents, which provides genetic evidence that different mechanisms are involved in differential cytotoxicity induced by Pt compounds. The results also demonstrate the utility of such a panel of mutants, constructed on the same genetic background, for detecting specific cellular response; presumably, this reflects the recognition or processing of specific DNA adducts. In conclusion, because the rad1 and rad3 gene products are determinants of cellular response to a large number of platinum-containing compounds, the present results support a critical role of genes involved in cell cycle control in cellular sensitivity to these agents.

Cell Cycle↗
PubMed1998

Improved efficacy and enlarged spectrum of activity of a novel anthracycline disaccharide analogue of doxorubicin against human tumor xenografts.

On the basis of a structure-activity study of a new series of anthracycline disaccharides, we recently identified a doxorubicin analogue (MEN 10755) with a promising antitumor activity. In the present study, to better support the pharmacological interest of MEN 10755, we extended the preclinical evaluation of antitumor efficacy to a large panel of 16 human tumor xenografts, which originated from different clinicopathological types. Tumors with typical multidrug-resistant phenotype were excluded because MEN 10755 was found unable to overcome resistance mediated by transport systems. In the doxorubicin-responsive series, MEN 10755 exhibited a higher activity in three of five tumors, as documented by a more marked tumor growth inhibition and an increased value of log-cell kill. In the series of doxorubicin-resistant tumors, MEN 10755 was found effective in 6 of 11 tumors (1 breast, 3 lung, and 2 prostate carcinomas). The overall response rates were 31% and 69% for doxorubicin and MEN 10755, respectively. The improvement in drug efficacy was also supported by a substantial increase in the long-term survivor rate of animals implanted with responsive tumors. Most of the tumors refractory to doxorubicin and responsive to MEN 10755 were characterized by overexpression of the antiapoptotic protein Bcl-2. In one of these tumors (MX-1 breast carcinoma), we examined the ability of MEN 10755 to induce phosphorylation of Bcl-2 after a single treatment with therapeutic doses. The results indicated that, unlike doxorubicin, MEN 10755 induced protein phosphorylation. A similar modification was produced by Taxol, which is known to be very effective against the tumor. The correlation between drug efficacy and Bcl-2 phosphorylation may underly a peculiar feature related to improvement of efficacy of the disaccharide analogue. In conclusion, the present study supports some favorable features of the novel doxorubicin analogue in terms of both efficacy and tolerability with comparison to doxorubicin, although the improvement is somewhat tumor- and schedule-dependent.

Animals↗
PubMed1997

Randomised study of radical surgery versus radiotherapy for stage Ib-IIa cervical cancer.

BACKGROUND: Stage Ib and IIa cervical carcinoma can be cured by radical surgery or radiotherapy. These two procedures are equally effective, but differ in associated morbidity and type of complications. In this prospective randomised trial of radiotherapy versus surgery, our aim was to assess the 5-year survival and the rate and pattern of complications and recurrences associated with each treatment. METHODS: Between September, 1986, and December, 1991, 469 women with newly diagnosed stage Ib and IIa cervical carcinoma were referred to our institute. 343 eligible patients were randomised: 172 to surgery and 171 to radical radiotherapy. Adjuvant radiotherapy was delivered after surgery for women with surgical stage pT2b or greater, less than 3 mm of safe cervical stroma, cut-through, or positive nodes. The primary outcome measures were 5-year survival and the rate of complications. The analysis of survival and recurrence was by intention to treat and analysis of complications was by treatment delivered. FINDINGS: 170 patients in the surgery group and 167 in the radiotherapy group were included in the intention-to-treat analysis; scheduled treatment was delivered to 169 and 158 women, respectively, 62 of 114 women with cervical diameters of 4 cm or smaller and 46 of 55 with diameters larger than 4 cm received adjuvant therapy. After a median follow-up of 87 (range 57-120) months, 5-year overall and disease-free survival were identical in the surgery and radiotherapy groups (83% and 74%, respectively, for both groups), 86 women developed recurrent disease: 42 (25%) in the surgery group and 44 (26%) in the radiotherapy group. Significant factors for survival in univariate and multivariate analyses were: cervical diameter, positive lymphangiography, and adeno-carcinomatous histotype. 48 (28%) surgery-group patients had severe morbidity compared with 19 (12%) radiotherapy-group patients (p = 0.0004). INTERPRETATION: There is no treatment of choice for early-stage cervical carcinoma in terms of overall or disease-free survival. The combination of surgery and radiotherapy has the worst morbidity, especially urological complications. The optimum therapy for each patient should take account of clinical factors such as menopausal status, age, medical illness, histological type, and cervical diameter to yield the best cure with minimum complications.

Adult↗
PubMed1997

The cell-specific anti-proliferative effect of reduced glutathione is mediated by gamma-glutamyl transpeptidase-dependent extracellular pro-oxidant reactions.

We have shown earlier that extracellular GSH can exert a cell-specific growth-inhibitory effect on human tumor cells. In the present study, 2 human ovarian carcinoma cell lines (A2780 and IGROV-1) were used to investigate the biochemical basis of the GSH growth-inhibitory effect. Whereas cells were resistant, A2780 cells were sensitive to a 1 hr exposure to GSH, as assessed by the growth inhibition assay. Analysis of relevant GSH-dependent enzymes indicated that A2780 cells had low level of GSH S-transferase, glutathione reductase and gamma-glutamyl transpeptidase (gamma-GT) activities in comparison with those of IGROV-1 cells, and GSH peroxidase activity was undetectable in A2780 cells. The GSH effect was reversed by catalase and by dithiothreitol, indicating the occurrence of oxidative phenomena resulting in the impairment of critical cellular thiols. Indeed treatment of cells with H(2)O(2) also resulted in growth inhibition, which was more marked in A2780 cells. The gamma-glutamyl acceptor glycylglycine, a co-substrate for gamma-GT, potentiated the growth-inhibitory effect of GSH, which in contrast was decreased by the gamma-GT inhibitors, serine-borate complex and acivicin, suggesting that the production of reactive forms of oxygen (probably H(2)O(2)) was mediated by cysteinyl-glycine after GSH hydrolysis. The results support that the growth-inhibitory effect of low GSH concentration is the result of oxidative damage related to extracellular GSH metabolism.

Catalase↗
PubMed1997

Intense neoadjuvant chemotherapy with cisplatin and epirubicin for advanced or bulky cervical and vaginal adenocarcinoma.

Twenty-two consecutive patients with bulky or locally advanced cervical or vaginal adenocarcinoma were treated with a neoadjuvant chemotherapy regimen consisting of nine weekly courses of cisplatin (50 mg/m2) and three courses of epirubicin (70 mg/m2) at Weeks 1, 4, and 7, followed by radical hysterectomy. Salvage radiotherapy was administered to inoperable patients, whereas postoperative treatment with irradiation or further chemotherapy was given to those with detection of risk factors at surgery. Three patients (14%) did not complete the planned courses of chemotherapy (one refused after the first administration, one had severe myelotoxicity, and one had severe nephrotoxicity). Twenty-one subjects received at least four courses of treatment and were therefore evaluable for response. We observed 4 clinically complete and 10 partial responses, accounting for an objective response rate of 67%. Eighteen subjects (82%) underwent surgery without serious complications. No histopathologic complete response was observed. The response rate is in the lower range observed with other regimens for squamous cell carcinoma. Although feasible, this regimen implies a significant risk of myelotoxicity. This enhanced toxicity may be justified only if balanced by long-term survival.

Adenocarcinoma↗
PubMed1997

Molecular mechanisms controlling sensitivity to toxic metal ions in yeast.

Contamination of the environment has made toxic metal ions a major health issue. The use of yeasts as model systems for the identification of molecular mechanisms that control sensitivity to these agents is particularly attractive because of the ease of genetic manipulation and the availability of the complete Saccharomyces cerevisiae genomic sequence. This paper reviews information on those genes and mechanisms that have been identified in both the budding yeast S. cerevisiae and the fission yeast Schizosaccharomyces pombe as being capable of modulating sensitivity to important toxic metals. The factors that influence sensitivity to toxic metal ions include cellular thiols (glutathione, phytochelatins, labile sulfide, and metallothioneins) and the products of genes directly and indirectly involved in the transport or sequestration of the metal ion. A complete understanding of the molecular basis of sensitivity to toxic metal ions in lower organisms is expected to provide useful insights in the metal ion detoxification pathways and diseases related to these pathways in humans.

Cadmium↗
PubMed1997

Relationship between folate-binding protein expression and cisplatin sensitivity in ovarian carcinoma cell lines.

It has been suggested that sensitivity of ovarian carcinomas to cisplatin is in part related to an endogenous folate deficiency. In this work, we investigated whether overexpression of the folate-binding protein (FBP), a receptor involved in folate transport, might be associated with cisplatin sensitivity. The results obtained on a panel of ten ovarian carcinoma cell lines that overexpress different levels of the FBP showed a statistically significant relationship between FBP overexpression and cisplatin responsiveness, with the most sensitive cell lines expressing higher FBP levels on their membrane than the less sensitive ones. The relationship was observed both in cells growing in standard medium-containing high-folate concentrations (2.3 microM) and in cells adapted to growth in low-folate (20 nM) medium. Analysis of two cisplatin-resistant cell lines derived from the cisplatin-sensitive IGROV1 ovarian carcinoma cell line indicated that resistance was associated with a significant decrease in FBP expression. However, the receptor does not appear to be directly responsible for drug sensitivity per se as different cell lines transfected with FBP cDNA did not become more sensitive to the drug. Together, the data suggest the possible predictive value of FBP in ovarian carcinoma, as higher levels of expression can be indirectly but significantly associated with increased drug sensitivity.

Carrier Proteins↗
PubMed1997

Role of determinants of cadmium sensitivity in the tolerance of Schizosaccharomyces pombe to cisplatin.

The genetic mechanisms underlying cisplatin (DDP) resistance in yeast were investigated by examining the cytotoxicity of DDP to Schizosaccharomyces pombe mutants that were either hypersensitive or resistant to Cd. Despite reports that have linked glutathione (GSH) to DDP resistance in human cancer cells, we found that a mutant of S. pombe that was hypersensitive to Cd by virtue of a 15-fold reduction in GSH level and lack of phytochelatin production was as tolerant as the wild-type strain to DDP. A mutant that harbored a mutation in hmt1, the gene encoding an ATP-binding cassette-type transporter for vacuolar sequestration of a phytochelatin/Cd complex, exhibited only mild hypersensitivity to DDP even though it was 100-fold more sensitive to Cd. Overexpression of hmt1 in wild-type or mutant cells conferred tolerance to Cd but failed to do the same for DDP. However, a strain that produced 6-fold more sulfide than wild-type cells was found to be 6-fold more resistant to DDP and twice as resistant to Cd; an association between DDP resistance and sulfide production was observed in three other strains that were examined, and overproduction of sulfide was accompanied by reduced platination of DNA. These results indicate that GSH and the GSH-derived phytochelatin peptides do not play critical roles in determining sensitivity to DDP in S. pombe but rather identify increased production of sulfide as a possible new mechanism of DDP resistance that may also be relevant to human cells.

Antineoplastic Agents↗
PubMed1997

Squamous carcinoma in situ of the ovary.

We report a case of a squamous cell carcinoma in situ of the ovary in a patient previously submitted to radical hysterectomy and pelvic lymphadenectomy for an epidermoid carcinoma of the uterine cervix. The histogenesis of epidermoid tumors of the ovary and their association with squamous malignancies of the uterine cervix are discussed.

Adult↗
PubMed1997

Apoptosis as a determinant of tumor sensitivity to topotecan in human ovarian tumors: preclinical in vitro/in vivo studies.

Preclinical and clinical studies have documented the pharmacological interest in camptothecin derivatives in the treatment of resistant tumors. In particular, topotecan, a water-soluble derivative, exhibited promising activity in pretreated ovarian carcinoma. The present study investigated the pattern of tumor response in two human ovarian carcinoma xenografts and in their cisplatin-resistant sublines characterized by different mechanisms of drug resistance. In IGROV-1/Pt1 cells, cisplatin resistance has been ascribed to a reduced susceptibility to apoptosis as a consequence of p53 mutation and inactivation of its function. In the A2780 cisplatin-resistant subline, which retained the wild-type p53 gene status, the development of resistance has been possibly related to increased cell ability to repair drug-induced DNA damage. The in vivo results of the present study showed that topotecan could overcome the resistance in A2780/CP but not in IGROV-1/Pt1 tumor xenografts. The pattern of tumor response following in vivo topotecan treatment correlated with drug ability to induce apoptosis but not with its in vitro antiproliferative activity. The antitumor efficacy of topotecan in the four tumors reflected a different cell response to drug-induced DNA damage, as suggested by different perturbations of cell cycle progression. Indeed, only in the subline refractory to topotecan in vivo, IGROV-1/Pt1, did we observe a persistent arrest of the cells in the S-phase, resulting in a cytostatic and not a cytotoxic effect, since a low level of apoptosis was induced by the drug. In conclusion, the current results support that determination of drug-induced apoptosis is a useful predictor of tumor response to topotecan in ovarian carcinomas and suggest that p53 gene status may be a critical determinant of cell response to topoisomerase inhibitors.

Animals↗
PubMed1996

Interaction of ionizing radiation with topotecan in two human tumor cell lines.

The effect of topotecan, a topoisomerase I inhibitor, on ionizing radiation-induced cytotoxicity was studied in 2 human tumor cell lines characterized by a different expression of the target enzyme. The cytotoxicity of topotecan alone or in combination with radiation was assessed in exponentially growing non-small-cell lung cancer (H460) and glioblastoma (GBM) cells using the colony-forming assay. An isobologram method was used to evaluate the treatment interaction. An apparent supra-additive effect in cell killing following drug-radiation-combined treatment was observed only in GBM cells exposed to topotecan for 24 hr. In the case of H460 cells, interaction varied from a strong infra-additive effect at low radiation doses to a slight supra-additive effect when cells were exposed to radiation doses greater than 3 Gy. Northern blot analysis indicated that topoisomerase I expression in H460 cells was 8-fold higher than that of GBM cells. Although the H460 cell line exhibited an increased sensitivity to topotecan, only in the GBM cell line (which expressed a lower level of topoisomerase I) did the drug potentiate the radiation cytotoxicity. The observation that the radiosensitization by topotecan was related to topoisomerase I level is consistent with a putative role of the enzyme in processes involved in the repair of radiation damage. It is conceivable that the modulation of enzyme function results in an effective reduction of cellular capability for repair of radiation damage only if the enzyme is not over-expressed. Although a precise role of topoisomerase I in the cellular response to ionizing radiations (in particular, in DNA repair) remains to be documented, such results suggest the potential interest of topoisomerase I inhibitors in combination with radiation therapy for tumors expressing low topoisomerase I levels.

Antineoplastic Agents↗
PubMed1996

Association between cisplatin resistance and mutation of p53 gene and reduced bax expression in ovarian carcinoma cell systems.

P53 status may be a determinant of chemosensitivity of tumor cells; however, its involvement in cellular resistance to cisplatin remains uncertain. To investigate the relationships between p53 and the development of resistance to cisplatin, the p53 gene status was studied in ovarian carcinoma cell systems which included two cisplatin-resistant variants (IGROV-1/Pt 0.5 and IGROV-1/Pt 1) selected in vitro after prolonged drug exposure of the cisplatin-sensitive parental IGROV-1 cell line. IGROV-1/Pt 0.5 and IGROV-1/Pt 1 cell lines exhibited a degree of resistance of approximately 6 and 14, respectively, following 96-h exposure to the drug and were cross-resistant to other DNA-damaging agents (ionizing radiation and melphalan). Resistance to cisplatin paralleled a reduced cell susceptibility to cisplatin-induced apoptosis. DNA single-strand conformation polymorphism analysis of exons 5-9 demonstrated the presence of two mutants alleles at exon 8 in the two resistant cell lines, in contrast to the parental IGROV-1 cell line which exhibited the wild-type p53 gene. Direct DNA sequencing revealed that the mutations consist of two nucleotide changes in the DNA-binding domain at codons 270 (T/A) and 282 (C/T). The consecutive levels of p53 protein were lower in IGROV-1 than in IGROV-1/Pt cells. Following exposure to ionizing radiation or cisplatin, accumulation of the p53 protein was markedly enhanced only in the sensitive cells. Concomitantly, the expression of WAF-1 protein was strongly induced in the parental IGROV-1 cells, whereas WAF-1 protein remained undetectable in the IGROV-1/Pt 1 subline after DNA-damaging treatment. Consistent with this finding is the observation that ionizing radiation caused a different pattern of cell cycle perturbation in sensitive and resistant cells. Northern blot analysis demonstrated a marked reduction in bax mRNA levels in IGROV-1/Pt 1 cisplatin-resistant cells. Cotransfection assays with wild-type or mutant p53 expression plasmids and a reporter gene plasmid that utilized the bax gene promoter to drive transcription of chloramphenicol acetyltransferase were consistent with the role of p53 in regulation of bax expression in these cells. Taken together, these observations support a role for mutations of the p53 gene in the development of cisplatin resistance in ovarian cancer as a consequence of loss of the ability of p53 to transactivate bax, an apoptosis-inducing gene.

Apoptosis↗
PubMed1996

Isolation and characterization of a cisplatin-resistant strain of Schizosaccharomyces pombe.

A cis-diamminedichloroplatinum [DDP (cisplatin)]-resistant population of Schizosaccharomyces pombe was developed through chronic exposure of the 972 h- strain to increasing concentrations of the drug. The resulting cells, designated wtr2, were 5.25-fold resistant to DDP, are resistance was retained by clone isolated from this population in the absence of drug for > or = 5 months. After backcrossing and isolation of a single clone, random spore analysis gave a segregation ratio close to 1:1 for DDP resistance and sensitivity. Tetrad analysis confirmed a mendelian 2:2 segregation, suggesting that a single nuclear gene was responsible for the DDP-resistant phenotype. Stable diploids obtained from the mating of a resistant spore carrying the ade6-216 marker with the mei2-102-ade6-210 meiosis-deficient mutant remained resistant, indicating that the resistant phenotype was expressed dominantly. There was no difference between the accumulation of the DDP analog [3H]dichloro(ethylenediamine)-platinum(II) into whole cells derived from the sensitive and the resistant spores obtained from the last backcross. The resistant clones from a single tetrad did not have an increased level of glutathione and were collaterally sensitive to cadmium and arsenite. We conclude that in S. pombe, a stable and dominant DDP-resistant phenotype can be mediated by a single allele, that the phenotype is not accompanied by cross-resistance to cadmium or arsenite, and that the mechanism is not associated with a significant alteration in glutathione level or DDP uptake.

Alleles↗
PubMed1995

Pre-operative interleukin-2 immunotherapy induces eosinophilic infiltration in colorectal neoplastic stroma.

Interleukin-2 (IL-2) may induce peripheral eosinophilia and this phenomenon is related with response to IL-2 immunotherapy in patients with metastatic renal cell carcinoma. In previous experiences is reported that preoperative course with IL-2 may reverse the surgery-induced immunosuppression. This study's objective is to evaluate the histological changes of inflammatory infiltration in tumour stroma, in patients pretreated with IL-2 immunotherapy. 7 patients admitted to our surgical department with resectable recurrent colorectal cancer were treated with pre-operative course of IL-2; the tissue samples were analyzed for eosinophilic and inflammatory infiltration and compared with the samples obtained in the primary operation, performed without immunotherapy. In all patients were observed an increase of eosinophilic infiltration in tumour tissue. The mean increase were 200%, with high statistical significance (p < 0.0001). IL-2 pre-operative immunotherapy is able to change the interaction between host and tumour, by modifying the histological inflammatory infiltration in colorectal cancer tissue.

Adult↗
PubMed1994

Characterization of an established human, malignant, glioblastoma cell line (GBM) and its response to conventional drugs.

A cell line, GBM, was established from a human malignant glioblastoma and was characterized with particular reference to its response to conventional drugs. The GBM cell line exhibited a 73 +/- 7 h doubling time in monolayer cultures. Expression of glial fibrillary acidic and S-100 proteins was observed. Karyotype analysis of GBM cells at early passages revealed the presence of two near-triploid clones (A and B) with multiple chromosome rearrangements; a 100% frequency for clone B was observed in the established cell line. GBM cells had tumorigenic properties, since the s.c. injection of cultured cells into nude mice gave rise to slowly growing tumors. The morphology of GBM cells was retained during in vitro and in vivo passages, as judged by light microscopy. GBM cells were relatively resistant to most conventional drugs; among the tested drugs, only taxol exhibited a marked cytotoxic effect comparable to that found in cells of a different tumor type. GBM cells were found positive for the epidermal growth factor receptor, HER2-neu and P-glycoprotein by flow cytometry of cells labelled with monoclonal antibodies. In spite of the expression of relatively high gamma-glutamyltransferase activity, the intracellular glutathione level was comparable to that of other chemosensitive tumor cells. This glioblastoma cell line is a suitable model for the identification and preclinical studies of new agents and provides an additional system to explore the molecular basis of the intrinsic drug resistance of glioblastoma.

Animals↗
PubMed1994

Topoisomerase I gene expression and cell sensitivity to camptothecin in human cell lines of different tumor types.

Topoisomerase I (topo I) gene expression and cell sensitivity to camptothecin were investigated in seven human cancer cell lines not selected in vitro for drug resistance. The cell lines were of different tumor origin, and included two ovarian carcinomas (A2780 and IGROV-1), a cervix squamous cell carcinoma (A431), an osteosarcoma (U2-OS), a glioblastoma (GBM) and two different clones of a malignant melanoma (665/2/60 and 665/2/21). Topo I gene expression was evaluated by Northern blotting analysis and cell sensitivity to camptothecin was determined using the colony-forming assay after a 1 h exposure to the drug. A wide range of drug sensitivity levels was found among the examined cell lines. Cell doubling times and distribution in cell cycle phases were not correlated with camptothecin cytotoxicity. In particular, the percent of untreated cells in S phase was not predictive of the drug sensitivity. No correlation was found between level of topo I gene expression and cell response to camptothecin. These results indicate that the level of topo I expression is not the only critical determinant of cell sensitivity to camptothecin in unselected human cancer cell lines. Therefore, topo I gene expression may not be a useful predictive parameter of tumor response.

Blotting, Northern↗