Mutations of TP53 do not correlate with the sensitivity to paclitaxel--a study using 27 gynaecological cancer cell lines.

The correlation between inactivation of the TP53 gene through mutation or the presence of high-risk human papillomavirus (HPV) DNA and intrinsic paclitaxel sensitivity was studied in 27 gynaecological cancer cell lines. IC(50) values, as a measure of drug sensitivity, were determined using a 96-well clonogenic assay. TP53 mutations were investigated with polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) and direct DNA sequencing. HPV status was studied with PCR using HPV consensus primers. TP53 mutations were found in 7/11 vulvar SCC cell lines. Only 2/9 endometrial and 1/7 ovarian cancer cell lines carried TP53 mutations. One vulvar and one endometrial cancer cell line were HPV-positive; both carrying HPV type-16 DNA. Thus, TP53 was functionally normal in 3/11 vulvar, 6/9 endometrial and 6/7 ovarian cancer cell lines. The IC(50) values for paclitaxel were 0.60-2.9, 0.49-2.3 and 0.40-3.4 nM in the vulvar, endometrial and ovarian cancer cell lines, respectively. No correlation could be demonstrated between inactivation of the TP53 gene and paclitaxel sensitivity in vitro; the cell lines were evaluated as one group or according to their anatomical origin or histology. Previous reports have given inconclusive results, partly due to the cell types used, i.e. normal, cancerous or transformed cells. Our results support the view that paclitaxel sensitivity of tumour-derived cancer cell lines is not related to the TP53 status.

A fragment library based on Gaussian mixtures predicting favorable molecular interactions.

Here, a protein atom-ligand fragment interaction library is described. The library is based on experimentally solved structures of protein-ligand and protein-protein complexes deposited in the Protein Data Bank (PDB) and it is able to characterize binding sites given a ligand structure suitable for a protein. A set of 30 ligand fragment types were defined to include three or more atoms in order to unambiguously define a frame of reference for interactions of ligand atoms with their receptor proteins. Interactions between ligand fragments and 24 classes of protein target atoms plus a water oxygen atom were collected and segregated according to type. The spatial distributions of individual fragment - target atom pairs were visually inspected in order to obtain rough-grained constraints on the interaction volumes. Data fulfilling these constraints were given as input to an iterative expectation-maximization algorithm that produces as output maximum likelihood estimates of the parameters of the finite Gaussian mixture models. Concepts of statistical pattern recognition and the resulting mixture model densities are used (i) to predict the detailed interactions between Chlorella virus DNA ligase and the adenine ring of its ligand and (ii) to evaluate the "error" in prediction for both the training and validation sets of protein-ligand interaction found in the PDB. These analyses demonstrate that this approach can successfully narrow down the possibilities for both the interacting protein atom type and its location relative to a ligand fragment.

Adenine recognition: a motif present in ATP-, CoA-, NAD-, NADP-, and FAD-dependent proteins.

Adenosine triphosphate (ATP) plays an essential role in energy transfer within the cell. In the form of NAD, adenine participates in multiple redox reactions. Phosphorylation and ATP-hydrolysis reactions have key roles in signal transduction and regulation of many proteins, especially enzymes. In each cell, proteins with many different functions use adenine and its derivatives as ligands; adenine, of course, is present in DNA and RNA. We show that an adenine binding motif, which differs according to the backbone chain direction of a loop that binds adenine (and in one variant by the participation of an aspartate side-chain), is common to many proteins; it was found from an analysis of all adenylate-containing protein structures from the Protein Data Bank. Indeed, 224 protein-ligand complexes (86 different proteins) from a total of 645 protein structure files bind ATP, CoA, NAD, NADP, FAD, or other adenine-containing ligands, and use the same structural elements to recognize adenine, regardless of whether the ligand is a coenzyme, cofactor, substrate, or an allosteric effector. The common adenine-binding motif shown in this study is simple to construct. It uses only (1) backbone polar interactions that are not dependent on the protein sequence or particular properties of amino acid side-chains, and (2) nonspecific hydrophobic interactions. This is probably why so many different proteins with different functions use this motif to bind an adenylate-containing ligand. The adenylate-binding motif reported is present in "ancient proteins" common to all living organisms, suggesting that adenine-containing ligands and the common motif for binding them were exploited very early in evolution. The geometry of adenine binding by this motif mimics almost exactly the geometry of adenine base-pairing seen in DNA and RNA.

Docetaxel and autonomic cardiovascular control in anthracycline treated breast cancer patients.

BACKGROUND: Taxoids are new chemotherapeutic agents effective in the treatment of breast cancer. Paclitaxel treatment has been reported to cause some cardiac side effects and both paclitaxel and docetaxel to cause mild, mainly sensory, peripheral neuropathy. Autonomic function tests are sensitive measures of autonomic neuropathy and cardiac regulation. The purpose of this study was to find out whether docetaxel changes neural cardiovascular regulation in breast cancer patients previously treated with anthracyclines. PATIENTS AND METHODS: Nine women treated for metastatic breast cancer with docetaxel were studied prior to the docetaxel treatment and after the third or fourth course. Autonomic cardiovascular function tests were performed and heart rate and blood pressure variability were assessed with power spectrum analysis. RESULTS: Heart rate variability or the heart rate responses to the autonomic function tests did not change after docetaxel treatment. The blood pressure response to standing was enhanced and systolic blood pressure variability decreased after three to four cycles of docetaxel. CONCLUSIONS: Docetaxel treatment did not deteriorate vagal cardiac control in breast cancer patients after exposure to epirubicin. The observed changes in blood pressure responses suggest that docetaxel changes sympathetic vascular control. However, these changes seem to be related to altered cardiovascular homeostasis rather than peripheral sympathetic neuropathy.

Impairment of heart rate variability during paclitaxel therapy.

BACKGROUND: Paclitaxel, which has been reported to be effective in treating metastatic breast carcinoma and advanced ovarian carcinoma, has been associated with cardiac side effects. Therefore, the effect of paclitaxel on cardiovascular autonomic regulation was studied. METHODS: Twenty-four-hour ambulatory electrocardiogram measurements were recorded twice from 14 women with breast or ovarian carcinoma: once before paclitaxel treatment and once on the day after the second chemotherapy course. Heart rate variability (HRV) was assessed with spectral analysis. For the frequency domain analysis, HRV was assessed in the very low (0.005-0.040 hertz [Hz]), low (0.040-0.150 Hz), and high frequency (0.150-0.400 Hz) spectral components. RESULTS: The ratio between low frequency and high frequency HRV decreased (daytime values of 2.7% [standard deviation (SD) 1.6] vs. 1.7% [SD 0.91; P = 0.0098) after 2 courses of paclitaxel. The circadian fluctuation of HRV also decreased in all studied frequency components. CONCLUSIONS: The observed changes in spectral characteristics suggest that autonomic modulation of the heart rate is impaired after paclitaxel therapy. However, from these data it is not clear whether the observed changes are permanent or whether autonomic cardiac function returns to normal some time after treatment. Further studies are needed to examine whether these indices based on HRV can be used to detect those patients at risk for cardiac side effects during chemotherapy.

Amplification and deletion of topoisomerase IIalpha associate with ErbB-2 amplification and affect sensitivity to topoisomerase II inhibitor doxorubicin in breast cancer.

Topoisomerase IIalpha (topoIIalpha) is a key enzyme in DNA replication and a molecular target for many anti-cancer drugs called topoII inhibitors. The topoIIalpha gene is located at chromosome band 17q12-q21, close to the ErbB-2 oncogene (HER-2/neu), which is the most commonly amplified oncogene in breast cancer. Because of the physical proximity to ErbB-2, copy number aberrations may also occur in the topoIIalpha gene. These topoIIalpha gene copy number aberrations may be related to the altered chemosensitivity to topoII inhibitors that breast cancers with ErbB-2 amplification are known to have. We used fluorescence in situ hybridization to study copy number aberrations of both topoIIalpha and ErbB-2 in nine breast cancer cell lines and in 97 clinical breast tumors, which were selected for the study according to their ErbB-2 status by Southern blotting. TopoIIalpha-protein expression was studied with Western blot and sensitivity to doxorubicin (a topoII inhibitor) with a 96-well clonogenic in vitro assay. Two of the five cell lines with ErbB-2 gene amplification (SK-BR-3 and UACC-812) showed amplification of topoIIalpha. In MDA-361 cells, ErbB-2 amplification (14 copies/cell) was associated with a physical deletion of topoIIalpha (four copies of chromosome 17 centromere and two copies of topoIIalpha). The topoIIalpha amplification in UACC-812 cells was associated with 5.9-fold-increased topoIIalpha protein expression and 2.5-fold-increased sensitivity to the topoII inhibitor, doxorubicin, whereas the deletion in MDA-361 leads to decreased protein expression (45% of control) and a 2.4-fold-increased chemoresistance in vitro. Of 57 ErbB-2-amplified primary breast carcinomas, 25 (44%) showed ErbB-2-topoIIalpha coamplification and 24 (42%) showed a physical deletion of the topoIIalpha gene. No topoIIalpha copy number aberrations were found in 40 primary tumors without ErbB-2 amplification. TopoIIalpha gene amplification and deletion are common in ErbB-2-amplified breast cancer and are associated with increased or decreased sensitivity to topoII inhibitors in vitro, respectively. These findings may explain the altered chemosensitivity to topoII inhibitors reported in ErbB-2-amplified breast cancers.

Carboplatin-paclitaxel- and carboplatin-docetaxel-induced cytotoxic effect in epithelial ovarian carcinoma in vitro.

BACKGROUND: The combination of paclitaxel and cisplatin is standard for patients with newly diagnosed epithelial ovarian carcinoma. The role of another taxane, docetaxel, currently is being studied. Due to its milder nonhematologic toxicity carboplatin increasingly is being substituted for cisplatin in taxane-based combinations. The purpose of this study was to compare the combination of carboplatin-paclitaxel with carboplatin-docetaxel in ovarian carcinoma in vitro, and to assess the type of interaction, if any. METHODS: Sensitivity to carboplatin and the concomitant use of a taxane and carboplatin was studied in 4 ovarian carcinoma cell lines using the 96-well plate clonogenic assay. Chemosensitivity was expressed as the IC50 value (i.e., the drug concentration causing 50% inhibition of clonogenic survival). IC50 values were obtained from dose-response curves after fitting the data to the linear quadratic equation. Synergism was studied by the area under the survival curve ratios (AUC ratios), obtained by numeric integration. The AUC ratio and the surviving fraction (SF) value after the administration of taxane alone were compared using the Student t test for paired data. RESULTS: The IC50 values for carboplatin were between 0.5-1.6 microgram/mL; there was only a 3.2-fold difference between individual cell lines. Carboplatin administered concomitantly with a taxane had either an additive or supra-additive growth inhibitory effect on all four ovarian carcinoma cell lines. A supra-additive effect occurred after simultaneous exposure of the cells to carboplatin at all tested paclitaxel concentrations in three of four cell lines (UT-OC-3, UT-OC-5, and SK-OV-3). The carboplatin-docetaxel combination had a supra-additive effect at the two highest docetaxel concentrations in two cell lines (UT-OC-4 and UT-OC-5) and at the highest docetaxel concentration in the other two cell lines (UT-OC-3 and SK-OV-3). CONCLUSIONS: Carboplatin has a synergistic effect when used with paclitaxel or docetaxel. A supra-additive effect is achieved with a wider range of paclitaxel concentrations than docetaxel concentrations.

Effects of paclitaxel with or without cremophor EL on cellular clonogenic survival and apoptosis.

Paclitaxel is currently formulated in a vehicle of 50% ethanol and 50% polyethoxylated surfactant cremophor EL. Cremophor EL has been reported to reverse P-glycoprotein-mediated multidrug resistance (MDR) at doses which are clinically achievable. It has also been reported to have a cytotoxic effect per se. In this study we used two different methods to evaluate the survival of cells exposed to paclitaxel with or without cremophor EL and the vehicle alone. Two laryngeal SCC cell lines (UT-SCC-19A and UT-SCC-29) and two ovarian adenocarcinoma cell lines (UT-OC-3 and UT-OC-5) established in our laboratory were investigated. Northern hybridisation was used to study the mdr-1 mRNA expression of the cell lines. With sensitive Northern analyses, these four lines yielded mdr-1 mRNA signals of the expected 4.5 kb size and of variable intensity, generally at higher levels than those in the positive control cell line KB. The 96-well plate clonogenic assay was used to obtain the fraction survival data and apoptosis was recorded by time-lapse video microscopy. Both methods indicate that cremophor EL alone has no effect on cellular survival. Consequently, paclitaxel without cremophor EL is as active as paclitaxel with cremophor EL in vitro.

Additive and supra-additive cytotoxicity of cisplatin-taxane combinations in ovarian carcinoma cell lines.

The purpose of this study was to compare the growth-inhibitory effect of cisplatin-paclitaxel with that obtained with a cisplatin-docetaxel combination and to assess the type of interaction. Concomitant use of taxanes and cisplatin was studied in seven human ovarian carcinoma cell lines, using the 96-well plate clonogenic assay. Chemosensitivity was expressed in terms of IC50 values, the drug concentration causing 50% inhibition of clonogenic survival. The type of interaction was studied using the area under the survival curve ratios (AUC ratios) obtained by numerical integration. Comparison of the AUC ratio and the surviving fraction (SF) value after taxane alone was made using Student's t-test. The influence of the drug concentration was tested by one-way analysis of variance (Anova). A supra-additive or additive effect was seen when seven ovarian carcinoma cell lines were exposed to paclitaxel or docetaxel concomitantly with cisplatin. A supra-additive effect was found in four cell lines (UT-OC-3, UT-OC-4, UT-OC-5 and SK-OV-3) after simultaneous use of cisplatin with all docetaxel concentrations tested, and in two cell lines (UT-OC-4 and SK-OV-3) when cisplatin was used concomitantly with paclitaxel. A more pronounced supra-additive effect was seen with the combination of cisplatin and docetaxel. The degree of supra-additivity was dose dependent, with increasing synergy after a higher taxane dose. The data obtained in this study suggest that a supra-additive or additive effect can be achieved in ovarian carcinoma with the concomitant use of cisplatin and a taxane.

Radiosensitivity of dermal and tumor fibroblasts derived from the same patient.

The in vitro radiosensitivity of dermal fibroblasts has been found to vary between individuals, and a number of studies have also shown that this parameter correlates with radiation-induced late injuries in clinical radiotherapy. In addition, certain genetic disorders are known to effect radiosensitivity, e.g. normal tissues of patients homozygous or heterozygous for the ataxia teleangiectasia gene show unusual sensitivity to radiation both in vivo and in vitro. Thus, it has been assumed that there is a genetically determined component resulting in a certain intrinsic cellular radiation response in an individual. To study this possible relationship between different cells of a specific patient, we established eight pairs of dermal and tumor fibroblast cultures. The donor patients had either adenocarcinoma of the uterus or squamous cell carcinoma (SCC) of the head and neck. The radiosensitivity of these strains was determined by a 96-well plate clonogenic assay, previously used by us for radiosensitivity testing of cancer cells. From a paired comparison, the values for the cell fraction surviving 2.0 Gy (SF2), of both fibroblast strains, were found to be on the same level in five out of eight cases. In patient 6, the SF2 of tumor fibroblasts was significantly higher than that of dermal fibroblasts (P=0.0014). In two additional cases the tendency was the same, but not statistically significant. As groups, the two types of fibroblasts did not differ from each other, mean SF2 values of 0.24+/-0.07 and 0.21+/-0.05, respectively. The SF2 of tumor fibroblasts from SCC patients proved to be significantly higher than that of the adenocarcinoma patients (P=0.030). These preliminary results indicate that the in vitro radiosensitivity of tumor fibroblasts correlates with normal cell sensitivity in many cases, but not in all. The radiosensitivity of tumor fibroblasts also seems to follow the level of in vitro radiosensitivity determined for the corresponding histological type of tumor cells. Further studies are needed to determine more closely the relationship between the radiosensitivities of tumor cells and tumor fibroblasts, thus evaluating the possibility of testing radiosensitivity from tumor fibroblasts in order to estimate tumor response.

p53 mutations and presence of HPV DNA do not correlate with radiosensitivity of gynecological cancer cell lines.

OBJECTIVE: The correlation between p53 tumor suppressor gene mutations and the presence of high-risk human papillomavirus (HPV) DNA with the in vitro radiosensitivity of gynecological malignancies was studied in 26 cell lines derived from gynecological cancers of 23 patients. METHODS: Comparison of the intrinsic radiosensitivity was performed with mean inactivation dose (D) determined with the 96-well plate clonogenic assay. p53 mutations were investigated with polymerase chain reaction and single-strand conformation polymorphism (PCR-SSCP) analysis and direct DNA sequencing, and the presence of HPV DNA was studied with PCR using HPV consensus primers. RESULTS: p53 mutations were found in 6 of 10 vulvar squamous cell carcinoma (SCC) lines. Nine vulvar and 1 vaginal SCC cell lines were HPV DNA negative and 1 vulvar cell line was HPV 16 positive. All 4 cervical SCC lines were HPV positive and possessed the wild-type p53. Three cell lines expressed HPV 16 and 1 HPV 68. Among 10 endometrial cancer cell lines, 2 cell lines with mutant p53 and 1 HPV 16 positive cell line were found. No correlation could be demonstrated between inactivation of the p53 gene and radiosensitivity in vitro; the cell lines were evaluated as one group or according to their anatomical origin or histology. CONCLUSION: Our results indicate that inactivation of the p53 gene through mutation or binding with HPV DNA does not increase the resistance of gynecological malignancies to ionizing radiation in vitro.

Paclitaxel changes sympathetic control of blood pressure.

Paclitaxel has become part of standard therapy in the treatment of ovarian and breast cancer. Concern has been raised about the effects of paclitaxel on cardiovascular function. Therefore, this study of the effects of paclitaxel on autonomic cardiovascular control was initiated. Eighteen women treated for ovarian or breast cancer were examined with autonomic cardiovascular function tests, once before the treatment and once after the second course of paclitaxel. Heart rate and blood pressure variability and changes in heart rate and blood pressure responses to the tests were measured. Baroreflex sensitivity was calculated from the Valsalva manoeuvre non-invasively. Paclitaxel did not change heart rate variability at rest compared with the pretreatment level. However, medium frequency variability of blood pressure was smaller after treatment with paclitaxel. Paclitaxel treatment did not impair the heart rate and blood pressure responses to the autonomic function tests. The results do imply that paclitaxel alters sympathetic control of blood pressure. Nevertheless, paclitaxel does not appear to precipitate autonomic cardiac neuropathy.

Taxane sensitivity of ovarian carcinoma in vitro.

Paclitaxel, the first clinically available taxane, has proven to be effective in the treatment of ovarian carcinoma. Docetaxel is the second taxoid derivative which has also shown activity in ovarian carcinoma. These two compounds have clear differences in pharmacokinetics and side-effects. In the present study we have tested the cytotoxic effect of docetaxel in seven ovarian carcinoma cell lines using the 96-well plate clonogenic assay. These results have been compared with data obtained from our recent study on cisplatin and paclitaxel sensitivities of the same cell lines. Chemosensitivity has been expressed as IC50 value, the drug concentration causing 50% inhibition of clonogenic survival. The IC50 values for docetaxel were 0.23-2.30 nM showing a 10-fold difference between individual cell lines. On a molar basis, docetaxel was 1.2 to 2.6 times more active than paclitaxel in six out of seven cell lines. This may be explained by differences in the mechanism of action or by differences in other pharmacological properties.

High-dose chemotherapy with autologous stem cell support for the treatment of advanced ovarian cancer--initial experience in Uppsala and Turku.

BACKGROUND: With current standard-dose chemotherapy ovarian cancer is a chemosensitive but not chemocurable disease in the majority of cases. The widely used first-line chemotherapy including a platinum analogue combined with cyclophosphamide results in response rates of 60-80%. However, only 10-20% of patients with advanced disease are alive 5 years after the diagnosis. The efficacy of high-dose chemotherapy supported by autologous stem cell transplantation (ASCT) is currently under intensive investigation. METHODS: We report here our initial experiences of the use of high-dose chemotherapy supported by ASCT for patients with high-risk ovarian cancer. Two patients were treated at Uppsala University Hospital in 1992 and four patients at Turku University Central Hospital in 1994. RESULTS: The first four patients treated either after heavy previous chemotherapy or recurrent disease relapsed within 5-10 months. Two patients received high-dose therapy as part of first-line treatment. One of them had a relapse 18 months after therapy, the other one has been disease free for 28 months. No toxic deaths occurred, but the patients had neutropenic febrile episodes and moderate to severe gastrointestinal toxicity. CONCLUSIONS: Coordinated efforts in Nordic countries are indicated to evaluate the usefulness of high-dose therapy supported by ASCT in the treatment of advanced ovarian cancer.

Vulvar squamous cell carcinoma cell lines are sensitive to paclitaxel in vitro.

In the current study, paclitaxel sensitivity of eight vulvar squamous cell carcinoma (SCC) cell lines was tested using a 96-well plate clonogenic assay. The chemosensitivity was expressed as IC50 corresponding to the drug concentration causing 50% inhibition in clonogenic survival. IC50 values were obtained from dose-response curves after fitting the data to the linear quadratic equation. The paclitaxel sensitivity of the eight vulvar SCC cell lines expressed as IC50 varied from 0.6 to 2.9 nM. The observed differences between the individual cell lines were surprisingly small, only 4.8-fold at the most. Paclitaxel sensitivity of vulvar SCC cell lines is of the same magnitude as the paclitaxel sensitivity of endometrial and ovarian carcinoma cell lines tested in our preliminary experiments with the same assay. We have previously studied the intrinsic radiosensitivity of these vulvar SCC cell lines. No correlation could be found between radiosensitivity and paclitaxel sensitivity. These results indicate that vulvar SCC is consistently sensitive to paclitaxel in vitro. The role of chemotherapy in the treatment of vulvar carcinoma has not been clarified yet. The efficacy of paclitaxel should be tested further in clinical trials.

PAP smear after radiation therapy for cervical carcinoma.

Vaginal PAP smear is frequently used for the follow-up of cervical carcinoma after primary therapy. Irradiation induced atypia can interfere with cytological analysis and thus detection of a local recurrence, or simulate malignant atypia and cause unnecessary suspicion of recurrence. In this retrospective study we evaluated the reliability of cytological analysis and the reported frequency of irradiation induced atypia after radiotherapy. Eighty-nine patients treated for cervical carcinoma at Turku University Central Hospital during the years 1970-88 were included in the study. During the median follow-up of 34 months a total of 697 PAP smears were taken with a median of 7.8 samples per patient. During the follow-up 44 (50%) patients had a recurrent disease, which was local in 17 (39%) cases. Nine out of 12 PAP smears taken 0-60 days before detection of a local recurrence showed class III-V cellular atypia. However, three PAP smears showed class I-II, and were therefore false negative. The rate of false positive samples was only 3%. In 567 PAP smears irradiation induced atypia was indicated as present/not present (+/-) and it was positive in 89 (16%) samples. The detection rate was considerably higher (75%) in class II samples than in rest of the material. Irradiation induced atypia was detected in 28% of the PAP smears taken during the first four months after radiotherapy and the rate decreased thereafter. Cytological analysis of vaginal PAP smear was a reliable indicator of recurrence in most cases and is a valuable tool for the detection of local recurrence of cervical carcinoma after primary radiotherapy.

Paclitaxel and cisplatin sensitivity of ovarian carcinoma cell lines tested with the 96-well plate clonogenic assay.

Platinum based chemotherapy is the cornerstone of treatment in advanced ovarian carcinoma. Paclitaxel, an unique antimicrotubule agent has shown significant clinical activity in cisplatin-resistant tumours, indicating a lack of cross-resistance. To compare the in vitro sensitivity of ovarian carcinoma to cisplatin and paclitaxel, we tested 7 ovarian carcinoma cell lines with the 96-well plate clonogenic assay. Chemosensitivity was expressed as the IC50 value i.e. the drug concentration causing 50% inhibition of clonogenic survival. IC50 values were obtained from dose-response curves after fitting the data to the linear quadratic equation. The IC50 values for paclitacel were 0.4-3.4 nM, showing an 8.5-fold difference between various cell lines. The IC50 values for cisplatin were 0.1-0.45 ug ml-1 showing only a 4.5-fold difference. This variance is clearly smaller than the 25-fold difference observed with the same method in endometrial carcinoma cell lines (Rantanen et al, Br J Cancer 69: 482-86, 1994). In accordance with clinical findings, no cross-resistance or correlation between sensitivity to paclitaxel and cisplatin could be demonstrated.

In vitro concurrent paclitaxel and radiation of four vulvar squamous cell carcinoma cell lines.

BACKGROUND: The antitubule agent paclitaxel causes a cell cycle blockage in the most radiosensitive part of the cell cycle, the G2/M phase. The possible radiosensitizing effect of paclitaxel was tested in four vulvar (UM-SCV-1A, UM-SCV-1B, UM-SCV-2, and UM-SCV-4) squamous cell carcinoma (SCC) cell lines. METHODS: A 96-well plate clonogenic assay was performed with paclitaxel and radiation, both separately and concomitantly. Survival data were fitted to the linear quadratic model. The area under the curve, equivalent to the mean inactivation dose (D), was obtained by numerical integration. The effect of paclitaxel on radiosensitivity was measured as the AUC ratio (paclitaxel plus radiation: radiation alone). This ratio was compared with the surviving fraction (SFP) after paclitaxel alone. RESULTS: Paclitaxel concentrations of 0.4 to 2.0 nanomolar (nM) caused 1 to 70% inhibition of clonogenic survival. The AUC values of the cell lines were 1.9 to 2.9 gray. A full additive effect was observed when paclitaxel and radiation were administered concurrently; however, a supra-additive effect never occurred. The type of paclitaxel radiation interaction was not affected by the concentration of the drug nor did the type of interaction vary between cell lines studied. CONCLUSIONS: Paclitaxel and radiation used concomitantly produced a clear additive effect at all concentrations and in all vulvar carcinoma cell lines tested. Although no supra-additive effect was observed, the additive effect already in nM concentrations could be beneficial in clinical use and, therefore, requires further investigation.

High-dose chemotherapy with autologous stem cell support in advanced ovarian cancer.

Since 1981, over 300 patients reported with advanced or refractory ovarian cancer have been treated with high-dose chemotherapy supported by autologous bone marrow or peripheral blood stem cell transplantation. Partial or complete clinical response has been reported in 54-100% of the cases, but the median duration of the response in the majority of patients has been only a few months. It is obvious from the available data that high-dose regimens supported by autologous stem cell transplantation (ASCT) are not capable of inducing long-term survival in patients with heavy tumour burden or chemoresistant ovarian cancer. Recent reports on nearly 100 patients have described results of the use of high-dose chemotherapy as first-line treatment for patients with optimally debulked disease or negative second-look laparotomy. Response rates and survival have been better when compared to historical controls, but the efficacy of this treatment modality in inducing durable remission has not been tested in randomized trials. Most of the ongoing trials presented briefly in this review have been designed to evaluate the potential of high-dose therapy as first-line treatment in preventing the development of resistant tumour clones and recurrence. The role of sequential high-dose chemotherapy with ASCT as a part of primary treatment or as salvage therapy for chemosensitive recurrent disease is also under investigation.

Endometrial cancer cell lines are sensitive to paclitaxel.

We have previously reported a 24 fold difference in the cisplatin sensitivity and a 12 fold difference in carboplatin sensitivity of endometrial carcinoma cell lines. In this study as evaluate paclitaxel sensitivity of the same cell lines. We tested nine endometrial cancer cell lines with the 96-well plate clonogenic assay using limiting dilution. The chemosensitivity was expressed as IC50 value, the drug concentration causing 50% inhibition of clonogenic survival. IC50 values were obtained from dose-response curves after fitting the data to the linear quadratic equation. The IC50 values for paclitaxel were 0.49 - 2.3 nM showing only a 4.7 fold difference between various cell lines. No correlation could be demonstrated between in vitro paclitaxel and platinum analog sensitivities of endometrial adenocarcinoma cell lines. The variance in paclitaxel sensitivity of different cell lines was little. Our results suggest that endometrial adenocarcinoma cell lines tested with the same methods. The clinical efficacy of paclitaxel in the treatment of endometrial cancer should further be evaluated in clinical trials.