PubMed Health⌕ Search

Biomedical subjects

Y Remvikos

Publications and source records attributed to Y Remvikos.

At least 37 records · Page 2Linked to original sources
PubMed1993

Prognostic value of the S-phase fraction of breast cancers treated by primary radiotherapy or neoadjuvant chemotherapy.

Neoadjuvant chemotherapy for large operable breast cancers is being increasingly used for the purpose of "downstaging," so that the lesions become accessible to conservative treatment. Since tumor proliferative activity has been shown to be a major prognostic factor for breast cancers, we have studied the value of S-phase fractions established by flow cytometry on cytological samples at diagnosis, in 184 stage II or IIIa patients entered in a randomized trial comparing neoadjuvant to adjuvant chemotherapy. All patients were pre- or perimenopausal, and the median follow-up was for 43 months (24-64). Using the median value (5%) as cutoff, a high SPF was found to be associated with relapse (p < 0.0008), locoregional recurrence (p < 0.02), or metastasis (p < 0.003). However, when the patients were analyzed according to the type of treatment, significance was maintained for the patients in the primary radiotherapy arm (p < 0.003) but not for those in the neoadjuvant chemotherapy arm (p < 0.06). The overall rate of response to neoadjuvant chemotherapy was significantly lower for tumors with low SPF (56.5%), compared to tumors with high SPF (85.6%). Thus, SPF was no longer predictive of outcome when the tumors regressed by more than 50% after chemotherapy (p = 0.66), whereas it was highly predictive in the nonresponding patients (p < 0.0001). Our study has revealed that patients with low-SPF tumors, irrespective of response or treatment schedule, had similar prognosis (around 70% free of disease at 45 months), while the high-SPF nonresponders had a dismal prognosis, with less than 25% free of disease at 24 months. If our results are confirmed with a longer follow-up, proliferative activity of breast cancers should prove to be instrumental for the initial therapeutic decision of stage II or IIIa patients.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

Cell cycle modifications of breast cancers during neoadjuvant chemotherapy: a flow cytometry study on fine needle aspirates.

Breast cancer cells from 92 patients were obtained by repeated fine needle sampling and analysed by flow cytometry for cell cycle modifications during neoadjuvant chemotherapy. Modifications of the histograms were observed for 47 of the 71 informative cases (66%), the most frequent concerning S-phase (increase or decrease) and G2M accumulation. These modifications correlated well with the efficacy of cytotoxic chemotherapy (P < 0.0001). A significant relationship between clinical regression and pretreatment proliferative activity was also observed, with 31/35 (89%) responders in the high proliferation group (S-phase fraction > 5% or BrdU labelling index > 3.3%) compared to 20/36 (56%) in the low proliferation group (P < 0.002). For patients undergoing chemotherapy including doxorubicin, a high incidence of G2M accumulation was observed (33%), a modification which was rare (4.5%) for a regimen with no anthracycline, for which S-phase was the most frequently modified cell cycle compartment (64%). The measurement of the pretreatment tumour proliferative activity as well as the early kinetic modifications, as indicators of response, may prove interesting parameters for the future management of neoadjuvant chemotherapy.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1993

[Genetic heterogeneity of certain sporadic colorectal cancers].

Intratumoral heterogeneity provides information concerning the timing of genetic events which occur during colorectal carcinogenesis. In a series of 14 colorectal adenocarcinomas, the following genetic alterations were characterized: loss of heterozygosity on chromosomes 17 p, 1 p, 18 q, 5 q and 22 q, point mutations on TP53 and K-RAS genes, change in DNA index. Six of the 14 initial samples were investigated for putative genetic heterogeneity. In two cases, variations in genetic alterations on chromosome 17 p and gene TP53 were demonstrated. These events seem to occur at a late stage in colorectal carcinogenesis.

Adenocarcinoma↗
PubMed1993

Frequently elevated content of immunochemically defined wild-type p53 protein in colorectal adenomas.

Mutations of the p53 tumour-suppressor gene are considered to be rare in human colorectal adenomas, a premalignant state of the digestive tract. We have analysed a series of 32 exophytic tumours of the colon and rectum for the presence of p53 protein. In 26 of the 28 pure adenomas, the presence of significant levels of p53 proteins was established by a sensitive two-point enzyme-linked immunosorbent assay. The detectability of p53 protein was frequently limited to PAb 1801, recognizing an N-terminal epitope. Immunoblotting of the fractions captured by the monoclonal antibodies revealed that PAb 421 reacted exclusively with a 53-kDa species, whereas an additional 48-kDa band was detected after incubation with PAb 1801. In the adenomas, the mutant conformation-specific PAb 240 was always negative and no mutations were detected on exons 5-8 in three large and highly dysplastic lesions, selected for their high p53 protein content. The remaining four of the 32 tumours presented foci of cancer. Three of these were shown to contain 'mutant' PAb 240-reactive p53, and gene mutations were identified in two by denaturing gradient gel electrophoresis and sequencing of the amplified products. Intense p53 nuclear immunohistochemical staining was associated with the malignant areas. We conclude that a novel mechanism affecting the regulation of p53 protein could occur in colorectal adenomas.

Adenoma↗
PubMed1992

Effect of DNA ploidy classification on prognosis in breast cancer.

A series of 327 breast cancers was analyzed for DNA ploidy by flow cytometry from paraffin-embedded tissue, and the resulting DNA histograms were classified independently by 6 researchers in the field as DNA diploid (Di), aneuploid (An), tetraploid (Te), multiploid (Mu), or technically uninterpretable. The frequency of diploid, aneuploid, tetraploid and multiploid cancers varied from 28 to 41%, 33 to 49%, 8 to 21% and 2 to 6%. According to the scale Di-An-Te-Mu, DNA ploidy was not significantly associated with breast-cancer mortality by 2 classifiers, but if DNA euploid cancers (Di+Te) were tested against non-euploid, or diploid cancers against non-diploid, all classifiers found DNA euploid and diploid cancers to have better prognosis. Mortality associated with diploid or tetraploid cancers decreased with improving histogram quality and increasing uniformity of classification, whereas that associated with aneuploid cancers remained unaltered. Among the cases where all classifiers agreed on ploidy, tetraploid, diploid and aneuploid cancers were associated with 100%, 88% and 68% 5-year survival rates. In this sub-set the S-phase fraction and possibly DNA ploidy were independent prognostic factors, together with histological grade, axillary node status, and primary tumor size.

Breast Neoplasms↗
PubMed1992

BrdUrd/DNA flow cytometry analysis demonstrates cis-diamminedichloroplatinum (II)-induced multiple cell-cycle modifications on human lung carcinoma cells.

The treatment of cultured human cells by cis-diamminedichloroplatinum (II) (cis-DDP) has been shown to induce complex modifications in the cell cycle. Using dual parameter DNA/BrdUrd flow cytometric analysis, we were able to monitor the cell cycle traverse of a pulse-labeled cohort of cells in an asynchronous culture of the A549 cell line (human lung adenocarcinoma). Two major modifications of the cell cycle following cis-DDP treatment were observed: 1) after 24 h of treatment, the labeling index was significantly increased and was linked with a prolonged S-phase; the S-phase delay occurred rapidly after cis-DDP and was dose dependent but not exposure time dependent; 2) an accumulation of cells at the S/G2 transition with an onset approximately 12 h after cis-DDP contact, which was found to be dependent on both dose and duration of exposure. The cytokinetic results also predict maximal sensitivity to cis-DDP for G1 cells and minimal for G2 cells. In our model the late S/G2 accumulation was always preceded by a slowing down of the S-phase. However, only the former should be the correct indicator of cytotoxicity since it was correlated with cell survival as evidenced by a colony formation assay, under all treatment conditions.

Adenocarcinoma↗
PubMed1992

Proliferative activity of breast cancers increases in the course of genetic evolution as defined by cytogenetic analysis.

The prognostic value of proliferative activity and its relationship with steroid hormone receptors and histopathological grade have been demonstrated for breast cancers. However, nothing is known about the underlying mechanisms. In order to understand the chronology of the appearance of increased proliferative activities, we used a series of 760 consecutive breast cancers for which we had obtained S-phase fractions (SPFs) by DNA flow cytometry. When the absolute difference from a DNA index of 1.00 was compared to SPFs, a significant positive correlation was obtained (r = 0.39, p < 0.0001), indicating that the probability of observing a high SPF increases when tumors progressively deviate from diploidy. A highly significant correlation was observed for the hyperploid group when hypertetraploid tumors were excluded, as the SPFs increased progressively as the DNA indices decreased from 2.00 to 1.30. This observation suggested a relationship with the evolution of chromosomal abnormalities as determined by cytogenetic analysis. Indeed, in a subset of 52 cases for which sufficient metaphases were available, there was a highly significant correlation between the SPF values and the proportion of rearranged chromosomes in the tumor cells (r = 0.60, p < 0.0001). When SPFs were separated into low or high using the median value (4.5%), a correlation also existed with the genetic evolution, since they increased from diploidy to hypodiploidy and then, after endoreduplication, from tetraploidy towards triploidy, as determined by the chromosome counts. Our results substantiate the relationship between proliferative activity and steroid hormone receptors which follow the same model.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Evolution↗
PubMed1992

Increased p53 protein content of colorectal tumours correlates with poor survival.

Allelic losses on the short arm of chromosome 17 occur frequently in colorectal cancers. Despite the existence of other common molecular events such as loss of the long arms of chromosomes 18 and 5, it has been demonstrated that the former has the greatest prognostic significance. Of the various genes mapping to the commonly deleted sequence, the best candidate as a 'target' seems to be the p53 antioncogene. We applied our methods of detection of the p53 protein in a series of 78 colorectal cancers stored in a tumour bank from 1985 to 1989, for which the median follow-up was 42 months. Nuclear-attached p53 was quantified by flow cytometry and soluble p53 was assayed by ELISA. Both assays used a monoclonal antibody considered to be specific for a conformational epitope present only on the mutated protein. Fifty of the 78 tumours (64%) were found to present significant levels of p53 attached to the nucleus. A further two tumours contained high levels of p53 only in their soluble fraction. Thus, 52 out of 78 cancers (67%) were considered to be positive for p53. The p53 content correlated with 17p loss (P < 0.002), hyperdiploid DNA content (P < 0.001) and tumour site (P < 0.03), but not Dukes' stage (P = 0.15). p53 negative cases had a better overall survival than p53 positive ones (P < 0.03). When the 14 stage D tumours were excluded from the analysis, p53 was no longer significantly predictive of survival (P < 0.07), but remained predictive of recurrence (P < 0.02) and metastasis (P < 0.03). Multivariate analysis was not performed because of the small number of cases. Overall, disease-free and metastasis-free survival were compared to the positivity obtained either with pAb 421 and/or 1801 or pAb 240 since all three were used in the flow cytometric analysis, defining subsets of 421-, 1801+ and 421-, 1801-, 240+. The presence of nuclear protein presenting the mutation-specific epitope, recognised by pAb 240, was found to be the most discriminant. It must be noted that univariate survival analysis demonstrated that more than 80% of patients with p53-negative tumours were alive at 3 years vs less than 50% in the p53-positive group. A large prospective study should be conducted to define the exact prognostic significance of the p53 content of colorectal carcinomas.

Adenocarcinoma↗
PubMed1992

Immunocytochemical determination of estrogen and progesterone receptors on 50 fine-needle samples of breast cancer. A prospective study including biochemical correlation and DNA flow cytometric analysis.

In a prospective study of 50 consecutive fine-needle samples of breast cancer, determination of estrogen and progesterone receptors was performed by separate immunocytochemical and biochemical assays. Comparisons of immunocytochemical assays with biochemical assays were obtained in 42 cases (84%) for both steroid receptors and showed significant relationships for estrogen receptor (P less than 0.001, r = 0.85) and progesterone receptor (P less than 0.001, r = 0.89) when the percentage of labeled nuclei (immunocytochemical assay index) was considered. In addition, DNA flow cytometric analyses were performed on fine-needle samples in 34 cases, with measurable DNA ploidy and S-phase fraction in 33 (97%) and 31 cases (91%), respectively. These results show that (1) estrogen and progesterone receptor immunocytochemical assays are valuable tools for steroid receptor determination, and that (2) on the same fine-needle samples of breast cancer DNA flow cytometric analysis may be performed.

Adenocarcinoma↗
PubMed1992

Survival and acquired genetic alterations in colorectal cancer.

To set the basis for a precise assessment of new therapeutic approaches, the prognosis of patients with colorectal cancer should be evaluated with the highest precision. The recent discovery, in tumor cells, of somatically acquired genetic alterations believed to be instrumental in tumor behavior may provide new independent prognostic factors. In the present study, the usual prognostic factors and a set of genetic alterations, i.e., Ki-ras mutations, DNA content, and allelic losses on chromosome 17p, 18q, 5q, and 1p, were investigated in 109 colorectal carcinomas. Univariate analysis for correlation with 5-year survival showed the following significant associations: histological staging (P less than 0.00001), preoperative serum carcinoembryonic antigen concentration (P less than 0.002), DNA content (P less than 0.009), and allelic loss on the short arm of chromosome 17 (P less than 0.002) and 1 (P less than 0.03). In multivariate analysis, only histological staging and allelic loss on the short arm of chromosome 17 were found to be independently associated with shorter survival (P less than 0.0001 and P less than 0.004, respectively). Loss of 17p alleles in colorectal carcinoma thus appears to be a marker of tumor aggressiveness. Its monitoring may lead to an improved classification of patients when adjuvant chemotherapy is considered.

Aged↗
PubMed1992

[Genetic abnormalities in "sporadic" colorectal cancers].

There are many genetic abnormalities in colorectal cancers, and they can schematically be studied according to 3 approaches. 1. The quantitative abnormalities of the DNA content of the nucleus and the cell cycle are studied with flow cytometry. 2. Karyotypic abnormalities relating to the loss and/or gain of chromosomes or structural abnormalities are studied by cytogenetics. 3. Oncogene or anti-oncogene mutations carried out by these chromosomal segments are studied by molecular biology. When compared to the clinical data, some of these abnormalities have a prognostic value. They allow an insight into the fundamental mechanisms of colorectal carcinogenesis. Finally, they may allow predicting and assessing the efficacy of some adjunctive therapies, especially that of medication.

Chromosome Aberrations↗
PubMed1992

p53 from basic research to clinical applications.

Mutations on the TP53 tumor suppressor gene and allele loss on chromosome 17p, where this gene has been located, are among the most frequent alterations yet identified in human malignancies. The p53 protein is highly conserved through evolution and expressed in most normal tissues. Wild-type p53 has been shown to control normal cell proliferation possibly through transcriptional regulation. The wild-type TP53 gene can suppress cell transformation and neoplastic cell growth. In contrast, mutant TP53 has lost the tumor suppressing ability and, in most cases, has gained a transformation promoting ability. Many different TP53 mutations have common conformational and functional consequences on the p53 protein. However, all the TP53 mutants are not necessarily equivalent in terms of biological activity: some mutations confer a strong transforming ability, while others lead to truncated products with probably no biological function. Some mutants may exhibit a dominant behavior over wild-type TP53, others may be recessive. Point mutations of TP53 tend to occur on evolutionary conserved positions. However, the TP53 mutational spectrum differs among cancer types, and this fact may reflect different exogenous mutagens and endogenous factors contributing to human carcinogenesis. In defined types of malignancies, the tumors with TP53 alteration or tumors with allele loss on 17p are associated with more aggressive phenotypes than those without these alterations. For these malignancies, the monitoring of TP53 alteration should now be included in therapeutic trials. Germ line mutations on TP53 may also occur. Individuals with constitutional TP53 mutation have a predisposition to a wide variety of neoplasms. Further characterization of this predisposition will enable the definition of the best follow-up for these at-risk patients.

Animals↗
PubMed1991

Progesterone receptor detection and quantification in breast tumors by bivariate immunofluorescence/DNA flow cytometry.

A method was developed for the detection of progesterone receptors (PgR) by flow cytometry (FCM) in cell suspensions obtained from mechanically dispersed fragments of operated breast cancers. Two monoclonal antibodies were tested for sensitivity and specificity on four breast cancer cell lines of known PgR expression and a calibration curve thus established. A simple procedure was used to calculate the level of PgR expression, taking into account the relative displacement of total cellular fluorescence compared to nonspecific fluorescence for each sample and the average DNA content of the cells derived from the corresponding histograms. The PgR-specific immunofluorescence of the tumor specimens measured in arbitrary units (channels) was then transformed to fmoles/mg DNA by comparison with the calibration curve. The FCM-derived results were compared with those of a conventional immunoenzymatic PgR assay on 30 surgical samples. PgR content ranged from 10 to 22,000 fmoles/mg DNA and linear regression analysis yielded a good correlation (r = 0.86). With a threshold of positivity of 300 fmoles/mg DNA, the two methods concurred for 28 of 30 tumors (93%). Nine specimens were analyzed repeatedly, showing good reproducibility. This method could prove to be more useful than the biochemical assays on homogenates, since it allows the simultaneous analysis of receptor expression in individual cells and of DNA index (ploidy).

Antibodies, Monoclonal↗
PubMed1991

Breast cancer genetic evolution: I. Data from cytogenetics and DNA content.

A general scheme of chromosome alterations occurring during tumor progression is proposed from the cytogenetic study of 113 breast carcinomas. For 76 of these tumors, chromosome numbers and rate of chromosome rearrangements were correlated with DNA content studied by flow cytometry. A series of 536 cases was used as control for flow cytometry. The following evolution can be proposed: 1. occurrence of unbalanced rearrangements decreasing chromosome number and DNA content; 2. correlatively to the rate of chromosome rearrangements, formation of endoreduplications leading to hyperploid sidelines; 3. persistence of the near diploid cells and decrease of chromosome number to about 35 and of DNA index to .85; 4. more frequently, elimination of the near diploid cells and complete passage to hyperploidy; 5. further losses of chromosomes in the hyperploid tumors, whose karyotypes can decrease to about 55 chromosomes and a DNA index of 1.35; 6. eventually, occurrence of a second endoreduplication, leading to an apparent near tetraploidy. The rate of rearranged chromosomes may reach 80% in both near diploid tumors with 35-40 and hyperploid tumors with 55-65 chromosomes which can be regarded as those with the highest degree of tumor progression. It is shown that the increase of chromosome number and DNA index above diploidy is very limited, and that all tumors with more than 50 chromosomes and 1.35 DNA content passed through endoreduplication. This results in many possible losses of heterozygosity in these cases.

Adenocarcinoma↗
PubMed1991

Breast cancer proliferation measured on cytological samples: a study by flow cytometry of S-phase fractions and BrdU incorporation.

Cell kinetics have been shown to be an important predictor of clinical evolution of operated breast cancer. We established a method for the estimation of the proliferative activity of tumour cells obtained by fine needle sampling without aspiration (FNS), using simultaneously S-phase fractions (SPF) measured on DNA histograms and 5-bromodeoxyuridine (BrdU) labelling index (BLI) measured by flow cytometry. Biparametric BrdU/DNA flow cytometry could be performed in 122 of 189 (65%) consecutive patients. The mean BLI of the cytologically malignant FNS (118) was of 3.0 and the median of 2.2%. One hundred and forty-eight DNA histograms (78%) were suitable for SPF analysis, of which 141 presented malignant cells, showing a mean of 4.5 and a median of 3.5%, comparable to BLIs. These results were obtained from fluorescence peak area histograms with doublet discrimination and background subtraction allowing the measurements of SPFs as low as 0.4%. An excellent correlation was thus observed between BLIs and SPFs, for the 94 cases for which both results were available (r = 0.85). Infrequent discordances (9%) were noted with SPFs considerably higher than BLIs. Seven patients had three consecutive FNS of their tumour at weekly intervals before treatment. Some variability in the proportions of multiple subpopulations of tumour cells was observed on the DNA histograms. In contrast, proliferation indices (SPF or BLI) were reproducible, suggesting homogeneous growth rates. We conclude that an estimation of the proliferative activity of breast tumours at any stage of the disease is possible routinely by SPF and/or BLI analysis of FNS. At least one quantitative proliferation index could be obtained for 91% of patients.

Biopsy, Needle↗
PubMed1991

Studies on the influence of the presence of an activated ras oncogene on the in vitro radiosensitivity of human mammary epithelial cells.

The clonogenic cell survival to gamma-rays was determined in a human mammary epithelial cell line transfected by an activated ras oncogene in comparison to either the host untransfected cell line or the same cell line transfected by the neo gene. In contrast to previous observation of fibroblasts derived from a murine cellular system (NIH 3T3), the analysis of survival curves did not demonstrate an acquired radioresistance in the human ras transfected cells as opposed to the two other cell lines. In other words, the appearance of resistance to ionizing radiation does not seem to be a feature which can be generalized to all situations associated to activation of a specific oncogene (ras).

Breast↗