Class III ß-tubulin (TUBB3): more than a biomarker in solid tumors?

Class III ß-tubulin (TUBB3) is a prominent mechanism of drug resistance expressed in a variety of solid tumors and particularly in lung and ovarian cancer. In the classical view, TUBB3 expression and drug resistance have been linked, and together they have been associated with a perturbation in microtubule dynamics. In keeping with this observation, TUBB3 was associated with drug resistance only when chemotherapy included a taxane in its chemical composition. In this review, we demonstrate that the classical supposition about TUBB3 is not correct, and that instead TUBB3 expression is linked to drug resistance as a complex survival mechanism activated by microenvironmental conditions such as poor nutrient supply and hypoxia.

The epithelial-mesenchymal transition and the estrogen-signaling in ovarian cancer.

Epithelial ovarian cancer is the leading cause of death for gynecological cancer in most of the Western world; lethality ensues from the occurrence of occult metastasis within the peritoneal cavity, a process requiring the acquisition of capacity for migration and invasiveness by ovarian tumor cells (metastatic phenotype), and characterized by a complex series of interrelated cellular events. Unlike most carcinomas that dedifferentiate during neoplastic progression with loss of epithelial E-cadherin (epithelial to mesenchymal transition, EMT), ovarian carcinomas undergo transition to a more epithelial phenotype, early in tumor progression, with increased E-cadherin expression. Subsequent reacquisition of mesenchymal features is observed in late-stage tumors, and loss of E-cadherin expression or function is a factor in ovarian cancer progression. Changes in E-cadherin expression are indicative of the phenotypic plasticity that occurs in ovarian cancer, with a variety of signal transduction pathways impinging on the regulation of E-cadherin levels or subcellular distribution. Among them, the Snail transcription family, consisting of members SNAIL and SLUG, is thought to be mainly involved in the repression of E-cadherin expression, leading to EMT. E-cadherin, SNAIL, and SLUG also represent crucial targets of estrogen signaling. In this review, we discuss recent advances in the understanding of the role of estrogen signaling in the complex network underlying the phenotypic plasticity in ovarian cancer. Insight into the mechanisms involved will allow rational drug designs, aimed at the molecules critical to cellular signaling.

Preclinical in vivo activity of a combination gemcitabine/liposomal doxorubicin against cisplatin-resistant human ovarian cancer (A2780/CDDP).

Both gemcitabine and liposomal doxorubicin are antineoplastic drugs with clinical activity in platinum-refractory ovarian cancer. The purpose of this study was to evaluate the antitumor activity of a combination gemcitabine/liposomal doxorubicin administered to athymic mice bearing cisplatin-resistant human ovarian cancer (A2780/CDDP) xenografts. Emphasis was on the use of very low doses of each drug and of different dosing schedules. Data obtained showed that combined treatment with 80 mg/kg gemcitabine and 15 mg/kg liposomal doxorubicin produced a significant enhancement of antitumor activity compared with monotherapy at the same doses of these agents. Noteworthy is the fact that the majority of xenograft-bearing animals receiving the combination therapy demonstrated a complete tumor regression at the end of the study. A similar trend was observed when doses of both drugs were reduced to 20 mg/kg gemcitabine and to 6 mg/kg liposomal doxorubicin. Again, three out of ten mice receiving the combination were tumor free at the end of the study. No significant differences were observed in antitumor activity when comparing the simultaneous vs the consecutive dosing schedule. Remarkably, no additive toxicity was observed in any experimental trials. These data encourage clinical trials to prove the advantages of this combination treatment with respect to the single-agent chemotherapy in platinum-refractory ovarian cancer patients.

Epidermal growth factor-responsive laryngeal squamous cancer cell line Hep2 is more sensitive than unresponsive CO-K3 one to quercetin and tamoxifen apoptotic effects.

Epidermal growth factor receptor (EGFR) plays a role in laryngeal squamous cell carcinoma (SCC) development and progression. The flavonoid quercetin (Q) and the antiestrogen tamoxifen (TAM) inhibit proliferation of both primary laryngeal SCC and laryngeal carcinoma cell lines, through still uncharacterized mechanisms. We studied Q and TAM inhibitory effect on epidermal growth factor (EGF)-stimulated Hep2 and CO-K3 laryngeal squamous cell lines. Q and TAM (0.1-1.0 microM) induced more apoptosis in EGF growth-stimulated than in unstimulated Hep2 cells. EGF neither stimulated CO-K3 cell growth nor enhanced Q and TAM-induced apoptosis. Mitogen-activated protein kinase (MAPK) analysis revealed that in Hep2 cells, but not in CO-K3 cells, EGF induced a time-dependent phosphorylation of p42, p44, p38, and p46. In Hep2 cells, but not in CO-K3 cells, Q and TAM produced, upon EGF treatment, a twofold increase of p38 and p46 and an enhancement of p42 and p44 dephosphorylation, suggesting a requirement of EGFR. The enhancing effect was due to a p38 and p46 dephosphorylation delayed kinetics. An antiphosphorylated p38 antibody prevented Q and TAM inhibitory effect on p42 and p44 phosphorylations, suggesting that the EGF-dependent increase in Q and TAM apoptotic effect on Hep2 cells could depend on the p38 inhibition of the survival kinases p42 and p44. In SCC, EGFR overexpression is an early event from dysplasia to neoplasia. We conclude that the capacity of Q and TAM to increase apoptosis in EGFR-activated cells makes these compounds possible chemopreventive drugs in subjects at risk of developing laryngeal cancer.

Antitumour activity of the silybin-phosphatidylcholine complex, IdB 1016, against human ovarian cancer.

This study aimed to assess, in an in vivo experimental model, the growth inhibitory effects of IdB 1016 (Silipide, a complex of silybin/phosphatidylcholine) when used as a single agent against human ovarian cancer. We also wanted to investigate the mechanism of the antiangiogenic action by assessing Vascular Endothelial Growth Factor (VEGF) levels and by using macroarray technology to evaluate the regulation of a panel of genes involved in angiogenesis. We also aimed to establish the plasma and tumour bioavailability of silybin after repeated administration of IdB 1016. Female nude mice bearing human ovarian cancer xenografts (A2780) received 450 mg/kg/day IdB 1016 daily by oral gavage until the end of the study. At sacrifice, blood and tumour specimens were collected and subsequently processed for the determination of silybin levels, VEGF levels or a gene expression profile. IdB 1016 was significantly active in inhibiting ovarian tumour growth. Treatment with 450 mg/kg/day for a total of 20 administrations produced a tumour weight inhibition (TWI%) of 78% and a Log10 Cell Kill (LCK) of 1.1. Free silybin levels were found to be 7.0+/-5.3 microg/ml and 183.5+/-85.9 ng/g tissue (mean+/-standard deviation (S.D.)) in the plasma and tumour samples, respectively. No significant differences were found in the concentration of human VEGF in xenografts from control and IdB 1016-treated mice. The array analysis suggested the downregulation of the VEGR receptor 3 and the upregulation of angiopoietin-2 as potential mechanisms for the antiangiogenic activity. In conclusion, these findings suggest IdB 1016 is a good candidate, with a relevant clinical potential, for use in the management of recurrent ovarian cancer. A phase II, non-randomised clinical study is now ongoing in our Institute aimed at evaluating the efficacy of daily administrations of IdB 1016 in the serological recurrence of ovarian cancer.

Quercetin abrogates taxol-mediated signaling by inhibiting multiple kinases.

Cell cycle block in G(2)/M initiates apoptosis, but the mechanism of this signaling cascade are largely unknown. The microtubule-perturbing agent Taxol has multiple effects on this signaling pathway and is a potent inducer of apoptosis. The specific pathways activated by low, clinically relevant concentrations of the drug are still largely unknown and are dependent on cell type and drug concentration. In this work, we have investigated why HeLa cells respond to Taxol by undergoing complete apoptosis, whereas MCF-7 cells remain in an intermediate phase with reduced death. Three phases were distinguished in these apoptotic pathways. The initial phase characterized by cellular detachment is followed by a second phase which includes the onset of apoptotic morphology, and p38 and Bcl-2 phosphorylation. These two phases are common to both cell lines. HeLa cells then proceed to the third and final execution phase, which culminates in death, whereas MCF-7 cells do not progress. Interestingly, the isoflavonoid Quercetin, a known general kinase inhibitor and an antioxidant, was able to prevent the onset of Taxol-induced cellular detachment and to protect from cell death. Moreover, it blocked Taxol-induced phosphorylation of p38 and Bcl-2, and prevented a Taxol-induced change in relative mobility of the apoptosis signal-regulating kinase 1 (Ask1). Our data elucidate the signaling pathways activated by Taxol at low clinically relevant concentrations.

Cell cycle checkpoint efficiency and cellular response to paclitaxel in prostate cancer cells.

BACKGROUND: Defects in the cell cycle machinery of prostate cancer cells might impair the efficiency of cell cycle checkpoints and affect the cell response to chemotherapeutic drugs. We examined the relationship between the status of microtubule damage-activated checkpoints and the response of hormone-refractory prostate cancer cells to paclitaxel. METHODS: The two cell lines DU145 and PC3 harboring defects at proteins involved in the regulation of checkpoints activated by microtubule damage were examined for cell sensitivity, apoptotic response, and efficiency of checkpoints in response to paclitaxel. RESULTS: In spite of a comparable sensitivity to the antiproliferative effects of paclitaxel, DU145 and PC3 cells exhibited different cell cycle control at checkpoints activated by microtubule damage. A transient mitotic arrest was induced by the taxane in both cell lines. However, PC3 cells underwent a rapid mitotic slippage and displayed a defective postmitotic checkpoint as evidenced by the appearance of polyploid cells. In this cell line, paclitaxel-induced cell death was a slow and delayed event, occurring also after S-phase re-entry. The mitotic checkpoint appeared to be more stringent in DU145 cells compared to PC3 cells. Moreover, despite the expression of mutated proteins involved in the prevention of DNA endoreduplication (p53, pRb, and p16(INK4A)), these cells did not progress into the cell cycle but efficiently underwent apoptosis by 24 hr. Such a response of DU145 cells was associated with phosphorylation of the p21(WAF1) protein. CONCLUSIONS: These observations evidence that activation of checkpoints following microtubule damage in prostate cancer may be regulated through complex mechanisms possibly involving p21(WAF1). Our findings support that the status of cell cycle checkpoints might affect the modality of cell death. However, the relevance of the mode of cell death for the sensitivity to taxanes remains to be determined.

In vitro and in vivo antitumor activity of the novel trinuclear platinum complex BBR 3464 in neuroblastoma.

PURPOSE: BBR 3464 is a promising new trinuclear platinum complex that has been shown to circumvent the resistance to cisplatin in a panel of tumor cell lines and xenografts with acquired or intrinsic resistance to cisplatin. The in vitro and in vivo antitumor activity of BBR 3464 was evaluated and compared with that of cisplatin in neuroblastoma. METHODS: In in vitro studies, the short- and long-term cytotoxicities, cell cycle perturbations, the ability to induce apoptosis, the intracellular platinum accumulation and DNA platination were evaluated in three neuroblastoma cell lines exposed to appropriate drug concentrations for 1 h. In in vivo studies, BBR 3464 was administered i.v. at doses of 0.30 and 0.35 mg/kg three times at intervals of 4 days (q4dx3), and cisplatin was administered i.v. according to two different schedules (at 2 and 4 mg/kg three times at intervals of 4 days and at 6 and 12 mg/kg as single doses). RESULTS: In a short-term growth inhibition assay, BBR 3464 was shown to be up to 100-fold more potent than cisplatin and it was even more potent in a clonogenic assay. The difference in the antitumor effect of BBR 3464 on the different cell lines was evident in both assays, while cisplatin exerted a comparable antitumor activity in all lines tested. Cell cycle analysis demonstrated a longer-lasting block in G2/M phase induced by BBR 3464 without the early S phase accumulation induced by cisplatin. The higher potency of BBR 3464 appeared to be unrelated to the induction of apoptosis, that was lower or at most comparable to cisplatin. Cellular platinum accumulation and platinum-DNA adduct formation following BBR 3464 exposure was higher than following cisplatin exposure. These differences may have resulted from a different mechanism of action and may explain the lack of cross-resistance with cisplatin. In xenografts of neuroblastoma, BBR 3464 was confirmed to be very potent as compared to cisplatin (MTD 0.35 mg/kg and 4 mg/kg for BBR 3464 and cisplatin, respectively). The efficacy of BBR 3464 was superior to that of cisplatin when both drugs were administered on a fractionated schedule (q4dx3), while BBR 3464 appeared equally active to 12 mg/kg cisplatin administered as a single dose. CONCLUSIONS: Our findings indicate that BBR 3464 has a definite antitumor effect in neuroblastoma lines and may be a candidate for early clinical trials in children with neuroblastoma.

The novel trinuclear platinum complex BBR3464 induces a cellular response different from cisplatin.

BBR3464 is a new platinum-based drug non cross-resistant with cisplatin. To characterise the cellular basis of BBR3464 cytotoxicity as opposed to cisplatin, we performed a comparative study of the two drugs in cisplatin-resistant neuroblastoma and astrocytoma cells. In both model systems, BBR3464 proved to be more potent than cisplatin and was able to overcome cisplatin resistance. The higher potency exhibited by BBR3464 correlated with an increased cellular platinum accumulation and DNA-adduct formation. At equitoxic doses, BBR3464 induced apoptosis to a lesser extent than cisplatin and failed to overcome the decreased susceptibility to cisplatin-induced apoptosis in cisplatin-resistant cells. Cell cycle analysis showed a dose-dependent G2/M arrest by BBR3464. In astrocytoma cells, cisplatin treatment resulted in the upregulation of p53, p21 and bax, while only p21 induction was observed after BBR3464 treatment. In cisplatin-resistant cells, the reduced sensitivity to cisplatin paralleled a resistance to the induction of p53/p21 pathway by cisplatin, while the same doses of BBR3464 induced p21 to a similar extent in the resistant cells as in the parental cells. In conclusion, BBR3464 induces a cellular response that is different from cisplatin, supporting the view that the two drugs act through different mechanisms. Our data indicate that BBR3464 may be a promising agent in the treatment of tumours unresponsive to cisplatin and with a non-functional p53.

A new method to evaluate in vitro myelotoxicity of antitumour agents in the first steps of drug development.

Research focused on the development of new anticancer agents has been based mainly on the assessment of the antitumour activity. This yields a large number of newly developed drugs endowed with good antitumour properties, but heavy side-effects on myelopoiesis. In this work, we validate a new method potentially useful to assess myelotoxic effect of newly developed agents. The proposed technique uses peripheral blood CD34+ cells as source of haematopoietic progenitors. These cells are grown in liquid culture in the presence of cytokines able to induce differentiation versus the three main lineages. Doxorubicin, carboplatin and topotecan served as reference drugs to investigate the accuracy of the technique. The three drugs mimick the effects reported in vivo. Doxorubicin and carboplatin produce a specific effect toward erythropoietic and thrombopoietic lineages, respectively, and topotecan a three-lineage toxicity. An advantage of the technique is the possibility to further investigate myelotoxicity. Here, we assessed differentiation markers in CD34+ cells to evaluate if the three drug treatments can affect the process of differentiation. Data show that the drug treatments were unable to modulate the expression of the selected differentiation markers in the surviving population. We propose this method as an innovative tool to score the myelotoxic effect of compounds in the first steps of drug development to further develop those compounds with the best ratio between activity and myelotoxic effects. Moreover, the fact that the method is performed in liquid phase allows its optimisation in a conventional "high throughput system".

Antitumour activity of novel taxanes that act at the same time as cytotoxic agents and P-glycoprotein inhibitors.

Taxanes antitumour agents such as paclitaxel and docetaxel represent a successful family of chemotherapeutic drugs. Unfortunately, acquired and innate resistance represents a clinical problem for these drugs. We investigated, on a panel of 7 human cancer cell lines, the growth inhibition effect of 3 newly developed taxanes (SB-T-1213, SB-T-1250 and SB-T-101187) with modification at the C10 and C3' positions of the taxane framework. These positions have been previously characterized as critical to make taxanes highly active against cells overexpressing the efflux pump P-glycoprotein (P-gp). Paclitaxel and docetaxel were used as reference compounds. Results unambiguously indicate the exceptional activity of the novel taxanes toward P-gp positive cells (up to >400 fold higher potency than that of paclitaxel). SB-T-1213 and SB-T-1250 are also substantially more active than the reference compounds against P-gp negative cells. To better understand the mechanisms underlying the enhanced activity of the newly developed taxanes, we performed cell cycle and apoptosis analysis. This study demonstrates that the striking growth inhibition effect exhibited by the novel taxanes is ascribed to their increased ability in inducing apoptosis and G(2)/M cell cycle block. SB-T-1213 and SB-T-1250 are also more active than reference compounds in inducing intracellular accumulation of the beta-tubulin subunits. Finally, it is revealed that these novel taxanes have ability to inhibit the function of the P-gp efflux pump on the basis of the Rhodamine 123 assay. These findings strongly suggest that SB-T-1213, SB-T-1250 and SB-T-101187 represent a new tool to overcome innate or acquired P-gp mediated taxane-resistance.

In vitro evaluation of newly developed chalcone analogues in human cancer cells.

PURPOSE: Among flavonoids, chalcones have been identified as interesting compounds having chemopreventive and antitumor properties. We studied a panel of newly developed chalcone analogues (S1-S10) using MDA-MB 231 and MCF-7 ADRr breast cancer cells and the T-leukemic Jurkat cell line. Quercetin was used as the reference compound. METHODS: Antiproliferative activity was evaluated by cell counts performed after 72 h of exposure to the drugs. DNA analysis and redox activity were evaluated using flow cytometry. Apoptosis was assessed by morphological analysis, using YOYO-1 as DNA dye; p-glycoprotein function was ascertained by quantitating the efflux of rhodamine 123. RESULTS: All cells were sensitive to chalcone analogues yielding IC50 in micromolar concentrations with the following order regardless of the multidrug resistance (MDR) status: S1 > S2 > quercetin. S1 and S2, the most active compounds, were selected to evaluate their effect on the cell cycle, apoptosis, redox activity, and modulation of the p-glycoprotein function. No significant perturbation in cell cycle was seen with concentration up to 1 microM after 24 h. After 72 h a slight increase in G2/M block and DNA fragmentation occurred at 10 microM. Morphological analysis of apoptosis showed that chalcone analogues induced apoptosis to a higher extent than quercetin. Redox analysis demonstrated that all substances were able to increase intracellular thiol levels, which returned to baseline value after 24 h for all drugs except quercetin. Production of reactive oxygen species was essentially unaffected by all compounds. Finally, in MDR-positive MCF-7 ADRr cells chalcone analogues were unable to modulate p-glycoprotein function while quercetin was able to. CONCLUSIONS: Newly developed S1 and S2 chalcones have a different but higher antitumor activity than quercetin and could be considered as potential new anticancer drugs.

Syntheses and biological activity of C-3'-difluoromethyl-taxoids.

A series of new taxoids bearing difluoromethyl group at the C-3' position and modifications at the C-10 and C-14 positions has been synthesized and their biological activities studied. The in vitro cytotoxicity assay results indicate that these newly developed taxoids exhibit comparable to several times better activity against drug-sensitive cell line LCC6-WT, and 40-70 times better activity against the corresponding drug-resistant cancer cell line LCC6-MDR as compared to that of paclitaxel. Apoptosis analysis has revealed the exceptional activity of SB-T-12843 (1e) in inducing apoptosis in both MDR-bearing and MDR-negative cancer cells.

Anti-tumour activity of a panel of taxanes toward a cellular model of human cervical cancer.

Using a model of human cervical cancer (ME-180 cells), the anti-tumour activity of paclitaxel was compared to that of docetaxel and IDN5109, a newly developed taxane. The growth inhibition effect of taxanes was assessed after 3 days of exposure. DNA analysis, the taxane-dependent modulation of the expression of the alpha and beta subunits of tubulin and DNA fragmentation were assessed by flow cytometry. The presence of apoptosis was confirmed by morphological analysis using a laser scan cytometer. For the evaluation of "in vivo" anti-tumour activity, taxanes were administered to nude mice intravenously once daily, according to a q3/4d x 4 schedule. Docetaxel, IDN5109 and paclitaxel obtained "in vitro" IC(50) values of 0.86, 1.4 and 2.4 nM, respectively. DNA analysis demonstrated a transient block at the G(2)/M phase of the cell cycle only after 12 h of culture in the presence of taxanes and an increase of nuclear fragmentation suggestive for apoptosis after additional 12 and 60 h of exposure. Morphological analysis confirmed the presence of apoptosis. Taxanes induced a down-modulation of the alpha subunit of tubulin in the G(0/1) phase of the cell cycle, and an overexpression of the beta subunit in the G(2)/M phase. A strong anti-tumour activity was obtained "in vivo" for nude mice xenografted using ME-180 cells (T/C=0% for all drugs). These data indicate that the three taxanes are strongly active both "in vitro" and "in vivo" toward ME-180 cells. Clinical studies are now needed to ascertain if the higher anti-tumour activity observed "in vitro" using docetaxel and IDN5109 yields a better clinical response in advanced cervical carcinoma with respect to paclitaxel.

Detection of apoptotic T lymphocytes in peripheral blood of human immunodeficiency virus (HIV)-infected subjects by apostain.

Apoptosis has been indicated as a mechanism of T cell depletion in HIV-infected subjects and useful in monitoring disease progression. We investigated for the presence of apoptotic T lymphocytes in 130 HIV subjects in various stages of disease by the newly developed cell permeant DNA dye Apostain. Blood was collected in EDTA, lysed in buffered ammonium chloride, fixed in freshly prepared 1% paraformaldehyde and stored in aliquots at -80 degrees C. Samples were thawed and double stained with FITC conjugated-CD3 monoclonal antibody and Apostain. Flow cytometry was then performed and T cells gated on a CD3 versus side scatter dot plot. Normal samples treated in the same manner served to establish the boundary separating non-apoptotic from apoptotic cells. There was no statistically significant association between the proportion of subjects with detectable apoptotic cells and CDC clinical categories A, B and C at the time of admission to the study, although a trend toward a lower apoptotic rate in category A (A= 29%, B=40% and C=41%) was noticed. Conversely, CDC T cell categories 2 and 3 contained significantly higher proportions of Apostain positive patients (1=6%, 2=32% and 3=49%, P=0.072, by chi(2) test). Most importantly, Apostain test identified subjects at risk of disease progression during a 3.5-7 months follow-up in CDC category B and 2 (P=0.008 and P=0.0003, by Fisher's exact test, respectively). A similar, albeit not statistically significant trend was observed also in the other categories. Not requiring extensive manipulation of fresh samples nor cumbersome culture techniques, Apostain test appears suitable for identifying HIV subjects at higher risk of disease progression in clinical settings.

Antagonistic effect of the combination gemcitabine/topotecan in ovarian cancer cells.

The in vitro interaction between the new antimetabolite gemcitabine (GEM) and topotecan (TPT) was analyzed in A2780 ovarian cancer cells. The growth inhibitory effect was assessed after 3 days of drug exposure. GEM and TPT obtained in vitro IC50 values of 2.1 +/- 0.9 and 33.7 +/- 10.2 nM, respectively. The interaction between GEM and TPT was evaluated by exposing cancer cells at increasing doses of GEM (0.1, 1, and 10 nM) and TPT (1, 10, 100, and 1000 nM). Analysis of data about the interaction between GEM and TPT was performed by applying the isobole method. An antagonistic effect was noticed when GEM was combined with TPT in the tested concentration range. DNA analysis was also performed and showed an augmentation of cells blocked in the G2/M phase during TPT exposure, while an increase of blocked cells in the G0/1, phase was observed after GEM treatment. This latter effect was predominant when the two drugs were used in combination. We also investigated the effect of sequential exposure to drugs, pretreating A2780 cells for 24 h with TPT and then for 48 h with GEM, and, conversely, pretreating A2780 cells with GEM for 24 h and thereafter with TPT for 48 h. Both these combined sequential treatments showed an antagonist effect of the drugs' combination. Long-term growth inhibition effect was established by clonogenic assay performed after 10 days of culture after drug treatment. Also these data confirmed the antagonistic effect between GEM and TPT in A2780 ovarian cancer cells.

Growth inhibitory effects and radiosensitization induced by fatty aromatic acids on human cervical cancer cells.

Evidences have been reported that phenylacetic (PA) and phenylbutyric (PB) fatty aromatic acids can exert tumor growth inhibition in vitro and in vivo. Moreover, clinical trials also showed some activity for these drugs to modulate the expression of genes implicated in tumor growth, metastasis, immunogenicity, and to potentiate the efficacy of cytotoxic agents. The aim of the study was to examine the effects of PA and PB on the growth as well as sensitization to cisplatin and radiation in human cervical cancer cells. The effects of PA and PB on the proliferative activity and apoptosis induction in cervical tumor tissue was investigated. Both PA and PB exhibited a time- and dose-dependent antiproliferative activity in SW756 and ME180 cell lines: after 72-h treatment, the IC50 (concentration able to inhibit 50% of cell growth) of PB was 1.9 +/- 0.2 mM and 1.5 +/- 0.2 mM in SW756 and ME180 cells, respectively, while the IC50 of PA was 13.0 +/- 1.7 mM and 10.0 +/- 1.2 mM in SW756 and ME180 cells, respectively. In tumor tissue biopsies obtained from patients affected by squamous cervical cancer, both drugs resulted in a marked reduction of the percentage of bromodeoxyuridine-labeled cells compared with untreated samples [19.0 +/- 1.63% in untreated tissues with respect to 1.30 +/- 0.54% and 4.20 +/- 2.50% of stained cells after treatment with PA (30 mM) (P < 0.0001) and PB (5 mM) (P < 0.0001), respectively]. Moreover, analysis of the staining with M30 monoclonal antibody revealed that PA (30 mM) and PB (5 mM) were able to produce a marked increase in the number of stained apoptotic nuclei with respect to untreated samples. Finally, PB and PA were shown to enhance the sensitivity of SW756 to radiation and to exert an additive effect when combined with cisplatin. A significant reduction of the processed form of p21ras and rhoB proteins in the membrane fraction of cells exposed to PA and PB was observed. When farnesol, which is able to circumvent the enzymatic step inhibited by PA and PB, was added to the medium only a partial reversal of the growth inhibition and potentiation of sensitivity to radiation induced by PA and PB were found. In conclusion, the growth inhibitory properties of fatty aromatic acids suggest that these molecules could represent the prototype of a new class of compounds with some therapeutic potential in cervical cancer.

Biological evaluation on different human cancer cell lines of novel colchicine analogs.

Three new 7-0-substituted deacetamidothiocolchicine derivatives have been evaluated for their antitumor activity against various human tumor cell lines, some of which express the multidrug resistance (MDR) phenotype, for their impact on the cell cycle and their binding to tubulin. Colchicine and thiocolchicine were used as reference compounds. Thiocolchicine was the most active agent on MDR-negative cells in terms of growth inhibition, whereas for multidrug-resistant cells, thiocolchicone was the most active compound (IC50 = 14 nM). As indicated by statistical analysis, a perfect agreement for the potency order (IC50 values) of the compounds between all the MDR-negative cancer cells (k = 1.00), a poor agreement between MDR-positive and MDR-negative cancer lines, and a moderate agreement (k = 0.50) between the two resistant cancer cells MCF-7 ADRr and CEM VBL were observed. To gain further insight into the mechanism of the antitumor activity of colchicinoids, the most active compounds, colchicone and thiocolchicone, were selected to evaluate their effect on cell cycle, apoptosis, and tubulin interaction. The highest recruitment activity into the G21/M phase of the cell cycle was detected in thiocolchicone-treated breast cancer cells. Interestingly, after 72 h of culture, when the cell cycle block subsided, a consistent amount of DNA fragmentation, a hallmark of apoptosis, was evident. Morphological analysis of MCF-7 ADRr cells confirmed this hypothesis and revealed that thiocolchicone was able to induce apoptosis in this MDR-bearing model. We also demonstrated, using flow cytometry, that thiocolchicone interacts with alpha- and beta-tubulin, thereby affecting the expression of both subunits.

Myofibroblastic tumours: neoplasias with divergent behaviour. Ultrastructural and flow cytometric analysis.

Myofibroblasts are spindle cells having ultrastructural features in common with smooth muscle cells and fibroblasts. In the last few years, tumours have been described in which myofibroblasts represent not only a reactive mechanism but also a true neoplastic component. They constitute new nosologic entities which might be termed "myofibroblastic tumours". Tumours with benign and, rarely, malignant behaviour are reported to belong to this group of lesions. Recently, a third tumour type with borderline biological course, named "inflammatory myofibroblastic tumour" (IMT), has been identified, a condition that has been regarded as a benign and reactive disorder for a long time. Only in recent reports has been demonstrated that, in spite of an apparently benign morphological pattern, some cases of IMT have a malignant course. In this connection, DNA analysis by flow cytometry is a valuable diagnostic tool, because it allows identification of the ploidy status, a procedure that is often useful for predicting the nature and the biological behaviour of the lesion. In this study, 11 cases of myofibroblastic tumours were examined retrospectively by evaluating clinicopathological features and DNA ploidy status by flow cytometry. The diagnosis of myofibroblastic tumour was confirmed by performing histology, immunohistochemistry, and electron microscopy in all patients. In detail, these 11 cases were composed of 1 benign myofibroblastoma, 1 myofibrosarcoma and 9 IMTs. Among these myofibroblastic tumours, all those with local recurrence or distant metastases (one myofibrosarcoma and three IMT) showed an aneuploid cell population demonstrable by flow cytometric analysis, whereas the other cases with benign course (one benign myofibroblastoma and six IMT) exhibited an euploid DNA content. These data suggest the following: a) Besides the rare myofibroblastomas and myofibrosarcomas, IMTs represent a larger group of lesions with potentially different biological and clinical course. b) DNA flow cytometric analysis is a reliable tool that support histopathological examination in characterizing those cases of IMT that, though being malignant, mimic benign lesions. Consequently, it establishes the basis for a different therapeutic approach according to the euploid or aneuploid DNA content.