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Biomedical subjects

A Alama

Publications and source records attributed to A Alama.

At least 19 recordsLinked to original sources
PubMed2006

Characterization of apoptosis induced by marine natural products in non small cell lung cancer A549 cells.

The effects of different marine derived agents were studied in A549 cell growth. These drugs induced cell cycle arrest at the G2-M phase associated with the up-regulation of GADD45alpha-gamma and down-regulation of c-Myc. In treated cells, GADD45alpha-gamma and c-Myc were up- and down-regulated, respectively. A cascade of events leading to apoptotic mitochondrial 'intrinsic' pathway was observed in treated cells: (1) dephosphorylation of BAD serine136; (2) BAD dissociation from 14-3-3 followed by its association with BCL-XL; (3) cytochrome c release; (4) caspase-3 activation, and (5) cleavage of vimentin. Caspase(s) inhibitor prevented the formation of cleavage products and, in turn, apoptosis was inhibited through a p53-independent mechanism. Moreover, these compounds did not activate NF-kappaB. Our findings may offer new insights into the mechanisms of action of these agents in A549 cells. The better understanding of their effects might be important to fully exploit the potential of these new drugs.

14-3-3 Proteins↗
PubMed2001

Antiproliferative activity and interactions with cell-cycle related proteins of the organotin compound triethyltin(IV)lupinylsulfide hydrochloride.

Organotin compounds, particularly tri-organotin, have demonstrated cytotoxic properties against a number of tumor cell lines. On this basis, triethyltin(IV)lupinylsulfide hydrochloride (IST-FS 29), a quinolizidine derivative, was synthesized and developed as a potential antitumor agent. This tin-derived compound exhibited potent antiproliferative effects on three different human cancer cell lines: teratocarcinoma of the ovary (PA-1), colon carcinoma (HCT-8) and glioblastoma (A-172). Cytotoxic activity was assessed by MTT and cell count assays during time course experiments with cell recovery after compound withdrawal. Significant cell growth inhibition (up to 95% in HCT-8 after 72 h of exposure), which also persisted after drug-free medium change, was reported in all the cell lines by both assays. In addition, the cytocidal effects exerted by IST-FS 29 appeared more consistent with necrosis or delayed cell death, rather than apoptosis, as shown by morphologic observations under light microscope, DNA fragmentation analysis and flow cytometry. In the attempt to elucidate whether this compound might affect genes playing a role in G1/S phase transition, the expressions of p53, p21(WAF1), cyclin D1 and Rb, mainly involved in response to DNA-damaging stress, were analyzed by Western blot. Heterogeneous patterns of expression during exposure to IST-FS 29 were evidenced in the different cell lines suggesting that these cell-cycle-related genes are not likely the primary targets of this compound. Thus, the present data seem more indicative of a direct effect of IST-FS-29 on macromolecular synthesis and cellular homeostasis, as previously hypothesized for other organotin complexes.

Antineoplastic Agents↗
PubMed2001

Thymidine labeling index analysis in early breast cancer patients randomized to receive perioperative chemotherapy.

OBJECTIVE: To identify through a substudy of a larger, multicenter study of adjuvant treatment in primary operable breast cancer patients any possible correlation between cellular proliferation rate, measured by thymidine labeling index (TLI), and perioperative chemotherapy (periCT). METHODS: TLI was measured in slices of early breast carcinoma patients. The main trial was designed to randomize patients after primary surgery to receive one cycle of periCT consisting of cyclophosphamide, epidoxorubicin and 5-fluorouracil, or no periCT. RESULTS: Of 600 patients randomized into the main study, 197 were eligible for inclusion in this substudy. Characteristics of patients were quite similar to those of the entire population entered into the main study. The TLI cutoff value in our series was 0.7% expressed as the median percentage ratio of thymidine-labeled cells undergoing DNA synthesis in the tumor cell population of specimens from the 197 patients. No differences were observed in terms of relapse-free survival (RFS) and overall survival (OS) after grouping the patients by TLI value (low and high) and by treatment. Among node-negative patients, a significant improvement in terms of OS (p = 0.02), but not RFS (p = 0.06), was seen in patients with a high-TLI value who underwent periCT versus controls. CONCLUSIONS: TLI may be a useful tool for the identification of node-negative patients with high-TLI values who may benefit from periCT.

Adult↗
PubMed1999

Increased cyclin D1 expression is associated with features of malignancy and disease recurrence in ovarian tumors.

Alterations in the expression of cyclin D1 have been reported frequently in several human cancers, but their significance in the multistep model of carcinogenesis has been scantly described. To define the pattern of cyclin D1 expression in the development of ovarian cancer and clinical outcome, 55 cases of benign ovarian tumors, 12 borderline cases, and 37 ovarian carcinomas (32 primary and 5 recurrent carcinomas) were studied. Analyses were carried out on fresh tumor specimens by Western blotting and reverse transcription-PCR and provided significant superimposable results (P = 0.00001). Cyclin D1 abundance was classed according to the densitometric values as undetectable, detectable, well detectable, and highly detectable. A significant increase (P < 0.000001) in median cyclin D1 values was observed from benign (0.038; range, 0.001-0.705) to borderline (0.226; range, 0.001-0.623) to malignant (0.347; range, 0.027-2.330) to recurrent (0.887; range, 0.309-2.2260) tumors. In addition, higher median cyclin D1 values were reported in serous carcinomas (P = 0.058) and advanced-stage diseases (P = 0.003). Survival analyses carried out in the 32 primary carcinomas showed no significant difference in overall survival between detectable versus well/highly detectable cyclin D1 neoplasms. Conversely, a significant relationship between cyclin D1 expression and progression-free survival was found (P = 0.031). These results may elucidate the function of altered cyclin D1 expression in ovarian tumorigenesis and provide a basis for additional studies on its prognostic role.

Biomarkers, Tumor↗
PubMed1998

Control of cyclin D1 expression by antisense oligonucleotides in three ovarian cancer cell lines.

Cyclin D1 is a critical gene controlling the G1 phase progression through the cell cycle. Alterations of cyclin D1 have been demonstrated in a variety of cancer types. We recently reported that increased cyclin D1 expression is associated with malignancy also in ovarian tumors. Three human ovarian cancer cell lines (SW626, OVCAR-3, IGROV1), expressing high levels of this gene, were used to investigate the effects induced by antisense oligonucleotides to cyclin D1 as antiproliferative compounds. Unmodified 18 mer oligomers, targeted to the translation start site of the cyclin D1 cDNA, were able to inhibit the growth of the three cell lines after a single administration of 40 microM. The pattern of cell number reduction ranged between 30 and 55% after 48 h of treatment. Moreover, by RT-PCR and Western blotting, a marked decrease of the cyclin D1 transcript and protein (up to 77% in the SW626) was detected after 24 and 48 h, respectively, from antisense exposure. Conversely, no relevant inhibition was reported in the sense-treated cells. The present data confirm the role of cyclin D1 expression in the proliferative behavior of ovarian cancer and provide additional information that might be helpful in the search for new therapeutic strategies of this disease.

Blotting, Western↗
PubMed1998

Synthesis and biological activity of gold and tin compounds in ovarian cancer cells.

We have investigated the patterns of in vitro cytotoxicity, induced by six newly synthesized gold and tin compounds, in three human ovarian cancer cell lines (SW 626, IGROV 1 and OVCAR-3). Four gold compounds, i.e. gold(I)lupinylsulfide hydrochloride [1] (containing a naked gold atom), triethylphosphinogold(I)lupinylsulfide hydrochloride [2], triphenyl-phosphinogold(I)lupinylsulfide hydrochloride [3] and 1 ,2-bis(diphenylphosphino)ethane bis[gold(I)lupinylsulfide] dihydrochloride [4] (all containing a gold atom coordinated with different phosphines), were prepared. Moreover, the triethylphosphinogold(I)(2-diethylamino)ethylsulfide hydrochloride [5] in which the simple diethylaminoethylthiol replaced the bulky lupinylthiol was synthesized. The tin compound, triethyltin(IV)lupinylsulfide hydrochlorlde [6], was also studied. Comparative tests with cisplatin, the most widely used antitumor agent in ovarian cancer, were carried out in biological Investigations. In vitro cytotoxicity, by MTT assay, showed that compound [4] and compound [6] exhibited interesting antiproliferative activity in all the three cell lines (mean IC50=1.3 and 0.7 microM, respectively) compared to cisplatin (mean IC50=4.8 microM). In addition, the PA-1 cell line, more sensitive to cisplatin (IC50=0.6 microM), was included as a comparison in the study. Cell count assays confirmed the cytotoxic properties of compounds [4] and [6] against the four cell lines, reporting higher growth Inhibition potency than cisplatin, with IC50 values in the sub-micromolar range.

Antineoplastic Agents↗
PubMed1997

Antisense oligonucleotides as therapeutic agents.

The potential for modulating gene expression by the use of antisense oligonucleotides has become increasingly interesting in recent years. Antisense oligonucleotides are complementary nucleic acid fragments that hybridize to target sequences within RNA to form a DNA-RNA duplex, resulting in the block of translation of messenger RNA into the protein. Advances in chemistry and molecular biology have provided the basis to develop antisense oligodeoxynucleotides and improve their selectivity, stability and specificity of action. The antisense technology has been extensively used in vitro and in vivo as a tool to study the regulatory mechanisms in biologic processes and as potential therapeutic agents in cancer, viral infections and genetic disorders. In the present review, the various approaches for the use of antisense molecules in oncology, virology, genetic and inflammatory diseases are described; several studies, supporting the in vitro and in vivo applications of this technology, are also presented. Moreover, the potential clinical use of antisense therapies is discussed.

Antineoplastic Agents↗
PubMed1997

Expression of cyclin D1 correlates with malignancy in human ovarian tumours.

Cyclin D1 is a cell cycle regulator of G1 progression that has been suggested to play a relevant role in the pathogenesis of several human cancer types. In the current study, the expression of cyclin D1 has been investigated in a series of 33 patients, with benign (10 patients), borderline (five patients) and malignant (18 patients) ovarian disease. Cyclin D1 protein and mRNA content were analysed by Western blotting and reverse transcriptase polymerase chain reaction respectively. The levels of cyclin D1 protein were undetectable in patients with benign disease, detectable in the majority of patients with borderline disease and elevated in those with ovarian carcinomas, being significantly related to the degree of malignancy (carcinoma vs benign, P = 0.0001; benign vs borderline, P = 0.0238). A significant relationship between cyclin D1 expression and tumour proliferative activity was also found (P = 0.000001). Moreover, eight benign lesions, two borderline tumours and 11 carcinomas proved to be suitable for the analysis of cyclin D1 transcript, and emerging data demonstrated significant agreement between protein abundance and mRNA expression. Results from the current study suggest that cyclin D1 expression is associated with the degree of transformation and most probably plays a role in the early development of ovarian malignancy.

Adolescent↗
PubMed1996

Establishment and characterization of three new cell lines derived from the ascites of human ovarian carcinomas.

Three human cancer cell lines (OC 314, OC 315, and OC 316) were newly established in permanent culture from the ascites of patients with serous adenocarcinoma of the ovary. OC 314 was derived from an untreated tumor presenting with ascites at diagnosis; OC 315 was isolated from a neoplasm progressing after cisplatin-containing regimen; and OC 316 was collected from a patient with pleural metastasis at diagnosis, resistant to different chemotherapeutic treatments including Taxol. These cell lines were repetitively subcultured once to twice a week through 75-80 passage generations. Tumor cells grew as monolayers and displayed epithelial-like morphology, consistent with a feature of adenocarcinoma, which was then confirmed by the expressions of cytokeratins and vimentin. The cell lines proved highly tumorigenic when transplanted into nude mice, both subcutaneously and intraperitoneally. In addition, the mice inoculated with subcutaneous OC 316 developed extremely aggressive tumor, also invading the peritoneum, which correlated with the malignant behavior of the original tumor. Drug sensitivity, evaluated by the MTT assay, showed that the three cell lines expressed similar sensitivity to doxorubicin. Responses to cisplatin essentially reported low sensitivity of OC 314 and OC 315 and resistance of OC 316, thus reflecting the original sensitivity at the clinical level.

Animals↗
PubMed1996

Inhibition of DNA polymerase alpha expression and cell growth, a possible triple helix mechanism.

The antiproliferative effects mediated by a 14-mer homopyrimidine oligonucleotide (5' CTTTCT-CTTTTCTC3'), designed to form DNA triplex with a purine region of the DNA polymerase alpha promoter, were evaluated on the human breast cancer cell line MDA-MB 231. In order to stabilize the triple complex under physiologic conditions, replacement of cytosines by methylcytosines in the oligomer sequence was carried out. Band-shift analyses demonstrated a complete triplex formation between the radiolabeled target duplex DNA and the methylcytosine-modified oligomer at the concentration of 0.1 microM under physiologic pH and temperature. A single exposure of MDA-MB 231 cells to 0.5 microM methylcytosine-modified oligonucleotide was able to markedly reduce the cell number and the percentage of cells in DNA synthesis up to 58% and 66%, respectively, compared with controls. Furthermore, a 48% reduction in the amount of the DNA polymerase alpha mRNA was reported after treatment with the oligomer. In conclusion, data from the present study demonstrate that an oligonucleotide to DNA polymerase alpha promoter, designed to form a triple helix with target double-stranded DNA, inhibits the expression of the reporter gene at the biologic and molecular levels, suggesting a possible triplex-mediated mechanism of action.

Base Sequence↗
PubMed1996

Oligonucleotides induce apoptosis restricted to the t(14;18) DHL-4 cell line.

Most human follicular B-cell lymphomas are associated with t(14;18) chromosome translocation that joins the bcl-2 gene with the IgH locus. This hybrid gene causes upregulation of BCL-2 protein expression, endowing cells with survival advantage. Although early BCL-2 overexpression is definitely responsible for immortalization/transformation, its exact role in the overt transformation as well as in the maintenance of the tumor phenotype is not known. The capacity of oligodeoxynucleotides (ODN) to modulate gene expression specifically has been exploited to downregulate the overexpression of BCL-2 protein in the SU-DHL-4 human follicular B-cell lymphoma line by the use of sense ODN or antisense ODN or antisense ODN designed to encompass the unique nucleotide sequence in the fusion region of the hybrid transcript. The specific downregulation of the bcl-2 transcript and of the relevant BCL-2 protein in the treated cells activated programed cell death and inhibited growing cells. The antitumor activity was restricted to the DHL-4 cell line carrying the specific nucleotide sequence at the bcl-2/IgH joining region. Thus, DHL-4 lymphoma cells derived from the acute phase of human follicular B-cell lymphoma, although endowed with additional activated oncogenes, were growth inhibited by bcl-2 downregulation with additional activated oncogenes, were growth inhibited by bcl-2 downregulation in a genetically restricted fashion. The biological activity was exerted exclusively by ODNs synthesized in the sense orientation. The sense ODNs have been proposed to anneal the hybrid bcl-2/IgH antisense RNA as identified in this study.

Amino Acid Sequence↗
PubMed1994

Relationship of variations in tumor cell kinetics induced by primary chemotherapy to tumor regression and prognosis in locally advanced breast cancer.

The relationship of changes in 3H-thymidine labelling index (TLI) induced by primary chemotherapy to tumor response and relapse rate in 36 patients with previously untreated locally advanced breast cancer (LABC) was analyzed. All patients received primary chemotherapy (3 cycles FAC), followed by mastectomy and subsequent adjuvant chemotherapy (3 FAC alternated with 3 CMF). Tumor TLI was evaluated immediately prior to primary chemotherapy and at the time of mastectomy. Median pretreatment TLI was used to discriminate between tumors with a high or low proliferative rate. Clinical objective response to primary chemotherapy was 83% in patients with high TLI and 56% for those with low pretreatment TLI (p = 0.06). Primary chemotherapy induced a > or = 50% reduction of the proliferative rate in 83% and 39% of the tumors with high and low pretreatment TLI, respectively (p = 0.006). Patients were classified into 4 groups according to TLI values both before and after primary chemotherapy: patients who remained in the high TLI group after primary FAC had the highest response rate (100%) and the lowest 2-year relapse rate (20%). These data suggest that: a) improved response to aggressive cytotoxic treatment occurs in tumors with high TLI at diagnosis; b) there is a significant correlation between TLI changes induced by primary chemotherapy and pretreatment proliferative activity; c) patients who remain in the high TLI group after primary chemotherapy are more likely to benefit from subsequent adjuvant systemic therapy.

Adult↗
PubMed1994

Tumour kinetics, response to chemotherapy and survival in primary ovarian cancer.

The analysis of thymidine labelling index (TLI) in relation to clinico-pathological variables and survival was carried out in 111 ovarian cancer patients. The significance of TLI in predicting response to aggressive first line chemotherapy regimens was examined. The overall median TLI value of 1.8% was used as a cut-off to discriminate slowly from highly proliferating cancers. 94 patients entered into two consecutive randomised trials, and were treated with six courses of cisplatin-based chemotherapy with or without doxorubicin. A significantly higher objective response of 60% was reported in the subset of patients with TLI > 1.8% as compared to 35% in patients with TLI < or = 1.8% (P = 0.03). In addition, patients achieving complete response had tumours with median TLI of 3.8% as compared to 2.4% for partial responders, 1.5% for patients with stable disease and 1.7% for those with progressive disease. A significant increase in tumour kinetics was observed in advanced cancers (P = 0.001), more undifferentiated tumours (P = 0.02) and postsurgical residual disease greater than 2 cm (P = 0.04). In univariate analysis, TLI failed to influence significantly clinical outcome: 26 versus 32 months median survival time for patients with high and low tumour TLI, respectively. In the Cox's regression model, the only independent prognostic variables were performance status and amount of residual disease after primary surgery (P = 0.000).

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Antiproliferative effect of DNA polymerase alpha antisense oligodeoxynucleotides on breast cancer cells.

Antisense oligonucleotides appear to offer considerable promise as sequence-specific inhibitors of gene expression. Different cellular targets for oligodeoxynucleotides with oncologic interest have been identified such as oncogenes, growth factors, and cell cycle-related genes. DNA polymerase alpha (pol alpha) plays a relevant role in DNA synthesis and cell proliferation. Pol alpha gene expression is constitutive throughout the cell cycle and its mRNA content and activity are related to the growth rate and neoplastic phenotype. The effects of a 18-mer pol alpha antisense oligomer on the proliferation of the MDA-MB 231 breast cancer cell line have been investigated. After 48 h in culture with oligomers (10 microM), about 50% growth inhibition was observed in antisense-treated cells, as evaluated by 3-(4,5-dimethythiazol-2yl)-2,5-diphenyltetrazolium bromide assay and cell count. [3H]Thymidine incorporation exhibited a 90% inhibition of DNA synthesis associated to 64% accumulation of cells at the G1-S border of the cycle as by flow cytometry, at 24 h. Northern hybridization and SDS-PAGE of immunoprecipitated MDA-MB 231 cell lysates revealed a decreased expression of pol alpha mRNA and a reduction of the 180-kDa polypeptide, respectively. Collectively, the data further confirm the relevance of pol alpha in the replicative cycle, as well as strengthen the potentiality of the antisense strategy for the control of gene expression and cell growth.

Adenocarcinoma↗
PubMed1993

Oligonucleotide degradation contributes to resistance to antisense compounds.

A subline of the human B cell lymphoma DHL-4, grown in the artificial serum-free medium HB101, displayed a resistant phenotype to the activity of an antisense oligodeoxynucleotide (aODN) effective on the parental DHL-4 line. It was found that the cellular uptake of the 18mer aODN in the two cell lines was almost the same. In contrast, the unresponsive subline DHL-4r degraded the aODN very efficiently, in contrast to the stability of aODN inside cells of the parental DHL-4 line. Activation of the degrading 'machinery' combined with selective properties of the artificial medium may be responsible for the loss of responsiveness to aODN.

Antineoplastic Agents↗
PubMed1992

Prediction of survival by thymidine labelling index in patients with resistant ovarian carcinoma.

The relationship between tumour proliferative activity, evaluated by thymidine labelling index (TLI), clinicopathological variables and clinical outcome, was analysed in a series of 64 chemotherapy-resistant, ovarian cancer patients. The median TLI of 4.6% (range 0.01-45.7) was used as the cut-off to discriminate rapidly from slowly proliferating tumours. Univariate analyses showed a significant advantage in survival for patients with TLI less than or equal to 4.6 (P = 0.0004), ECOG performance status less than or equal to 1 (P = 0.0001) and residual disease after primary surgery less than or equal to 2 cm (P = 0.019). Multivariate analysis demonstrated that performance status was the only independent prognostic variable, although TLI was the last covariate removed from the Cox's regression model.

Carcinoma↗
PubMed1991

The use of antisense oligodeoxynucleotides (aODNs) for the therapy of cancer.

Although specific cancer targets are difficult to identify, the recent development of antisense oligodeoxynucleotides (aODNs) as inhibitors of gene expression has been shown to provide a new and useful tool in antiblastic management. aODNs are able to specifically interact with gene or mRNA sequences and inhibit the expression of relevant molecules for cancer pathogenesis and progression. Since alpha-DNA polymerase (pol-alpha) plays an essential role in cell proliferation, aODNs to pol-alpha have been synthesized in order to block mRNA translation and affect the growth of MDA-MB 231, human breast cancer cell line and SW626 ovarian cancer cells. A rapid colorimetric test (MTT assay) which measures cell growth and survival has been employed to evaluate the effects induced by ODN treatment. The present experimental results demonstrate that the aODNs to pol-alpha are able to significantly affect cell proliferation. This study provides an encouraging basis for the exploitation of ODNs as therapeutic agents in vitro and in future clinical application.

Cell Division↗