S-phase accumulation precedes apoptosis induced by preoperative treatment with 5-fluorouracil in human colorectal carcinoma cells

Novel Therapeutic Combination Targets the Growth of Letrozole-Resistant Breast Cancer through Decreased Cyclin B1

As breast cancer cells transition from letrozole-sensitive to letrozole-resistant, they over-express epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK), and human epidermal growth factor receptor 2 (HER2) while acquiring enhanced motility and epithelial-to-mesenchymal transition (EMT)-like characteristics that are attenuated and reversed by glyceollin treatment, respectively. Interestingly, glyceollin inhibits the proliferation and tumor progression of triple-negative breast cancer (TNBC) and estrogen-independent breast cancer cells; however, it is unlikely that a single phytochemical would effectively target aromatase-inhibitor (AI)-resistant metastatic breast cancer in the clinical setting. Since our previous report indicated that the combination of lapatinib and glyceollin induced apoptosis in hormone-dependent AI-resistant breast cancer cells, we hypothesized that combination therapy would also be beneficial for hormone independent letrozole-resistant breast cancer cells (LTLT-Ca) compared to AI-sensitive breast cancer cells (AC-1) by decreasing the expression of proteins associated with proliferation and cell cycle progression. While glyceollin + lapatinib treatment caused comparable inhibitory effects on the proliferation and migration in both cell lines, combination treatment selectively induced S and G2/M phase cell cycle arrest of the LTLT-Ca cells, which was mediated by decreased cyclin B1. This phenomenon may represent a unique opportunity to design novel combinatorial therapeutic approaches to target hormone-refractory breast tumors.

Effect of First Line Gastric Cancer Chemotherapy Regime on the AGS Cell Line - MTT Assay Results

BACKGROUND

Combination chemotherapy regimes are common treatments for cancer. The aim of this study was to evaluation the effect of individual chemotherapeutic agents in comparison with a first line chemotherapy regime treatment in the AGS gastric cancer cell line by MTT assay.

MATERIALS AND METHODS

In this experimental study, AGS cells were grown in RPMI-1640 supplemented with 10% fetal calf serum and 100 IU/ml penicillin, and 10 μg/ml streptomycinin, under a humidified condition at 37° with 5% CO2. All cells were washed with PBS and detached with trypsin, centrifuged and 8000 cells re-plated on to 96- well plates. LD50 doses of Epirubicin, Cisplatin and 5-fluorouracil were added to each well in mono or triple therapy. Anti-proliferative activities were determined by MTT assay after 24, 48 or 72 h.

RESULTS

Results of MTT assays showed that there were no significant differences among 3 drugs in monotherapy (p=0.088), but there was significant difference between combination therapy with epirubicin (P=0.031) and 5FU (p=0.013) on cell survival at 24 h. After 48 and 72 hours, cell viability showed significant differences between the 3 drugs (p=0.048 and P=0.000 for 48 and 72 h, respectively) and there was significant difference between combination therapy with epirubicin (P=0.035 and P=0.002 for 48 and 72 h, respectively).

CONCLUSIONS

The results showed no significant differences between these chemotherapy drugs each given alone, but combination therapy with 3 drugs had significant effects on cell viability in comparison with epirubicin alone.

Structural modeling, in vitro antiproliferative activity, and the effect of substituents on the DNA fastening and scission actions of heteroleptic copper(ii) complexes with terpyridines and naproxen

A new series of heteroleptic copper(ii) complexes with terpyridines and naproxen are reported. The results of biological activity are laying a foundation for the design of new anticancer agents.

A tri-copper(II) complex displaying DNA-cleaving properties and antiproliferative activity against cancer cells

A new disubstituted terpyridine ligand and the corresponding tri-copper(II) complex have been prepared and characterised. The binding affinity and binding mode of this tri-copper complex (as well as the previously reported mono- and di-copper analogues) towards duplex DNA were determined by using UV/Vis spectroscopic titrations and fluorescent indicator displacement (FID) assays. These studies showed the three complexes to bind moderately (in the order of 10(4)  M(-1)) to duplex DNA (ct-DNA and a 26-mer sequence). Furthermore, the number of copper centres and the nature of the substituents were found to play a significant role in defining the binding mode (intercalative or groove binding). The nuclease potential of the three complexes was investigated by using circular plasmid DNA as a substrate and analysing the products by agarose-gel electrophoresis. The cleaving activity was found to be dependent on the number of copper centres present (cleaving potency was in the order: tri-copper>di-copper>mono-copper). Interestingly, the tri-copper complex was able to cleave DNA without the need of external co-reductants. As this complex displayed the most promising nuclease properties, cell-based studies were carried out to establish if there was a direct link between DNA cleavage and cellular toxicity. The tri-copper complex displayed high cytotoxicity against four cancer cell lines. Of particular interest was that it displayed high cytotoxicity against the cisplatin-resistant MOLT-4 leukaemia cell line. Cellular uptake studies showed that the tri-copper complex was able to enter the cell and more importantly localise in the nucleus. Immunoblotting analysis (used to monitor changes in protein levels related to the DNA damage response pathway) and DNA-flow cytometric studies suggested that this tri-copper(II) complex is able to induce cellular DNA damage.

Quantitative shape analysis of chemoresistant colon cancer cells: correlation between morphotype and phenotype

Morphological, qualitative observations allow pathologists to correlate the shape the cells acquire with the progressive, underlying neoplastic transformation they are experienced. Cell morphology, indeed, roughly scales with malignancy. A quantitative parameter for characterizing complex irregular structures is the Normalized Bending Energy (NBE). NBE provides a global feature for shape characterization correspondent to the amount of energy needed to transform the specific shape under analysis into its lowest energy state. We hypothesized that a chemotherapy resistant cancer cell line would experience a significant change in its shape, and that such a modification might be quantified by means of NBE parameterization. We checked out the usefulness of a mathematical algorithm to distinguish wild and 5-fluorouracil (5-FU)-resistant colon cancer HCT-8 cells (HCT-8FUres). NBE values, as well as cellular and molecular parameters, were recorded in both cell populations. Results demonstrated that acquisition of drug resistance is accompanied by statistically significant morphological changes in cell membrane, as well as in biological parameters. Namely, NBE increased progressively meanwhile cells become more resistant to increasing 5-FU concentrations. These data indicate how tight the relationships between morphology and phenotype is, and they support the idea to follow a cell transition toward a drug-resistant phenotype by means of morphological monitoring.

Selective killing of lung cancer cells using carcinoembryonic antigen promoter and double suicide genes, thymidine kinase and cytosine deaminase (pCEA-TK/CD)

The application of gene therapy in cancer treatment is limited by non-specific targeting. In the present study, we constructed a recombinant plasmid, containing a carcinoembryonic antigen (CEA) promoter and double suicide genes thymidine kinase (TK) and cytosine deaminase (CD), henceforth referred to as pCEA-TK/CD. Our results showed that the CEA promoter can specifically drive target gene expression in CEA-positive lung cancer cells. In the presence of prodrugs 5-flucytosine and ganciclovir, pCEA-TK/CD transfection decreased inhibitory concentration 50 and increased apoptosis and cyclomorphosis. Our result suggests that gene therapy using pCEA-TK/CD may be a promising new approach for treating lung cancer.

Microplate-reader compatible perfusion microbioreactor array for modular tissue culture and cytotoxicity assays

One important application of tissue engineering is to provide novel in vitro models for cell-based assays. Perfusion microbioreactor array provides a useful tool for microscale tissue culture in parallel. However, high-throughput data generation has been a challenge. In this study, a 4 x 4 array of perfusion microbioreactors was developed for plate-reader compatible, time-series quantification of cell proliferation, and cytotoxicity assays. The device was built through multilayer soft lithography. Low-cost nonwoven polyethylene terephthalate fibrous matrices were integrated as modular tissue culture scaffolds. Human colon cancer HT-29 cells with stable expression of enhanced green fluorescent protein were cultured in the device with continuous perfusion and reached a cell density over 5 x 10(7) cells/mL. The microbioreactor array was used to test a chemotherapeutic drug 5-FU for its effect on HT-29 cells in continuous perfusion 3D culture. Compared with conventional 2D cytotoxicity assay, significant drug resistance was observed in the 3D perfusion culture.

Effects of small interfering RNA targeting thymidylate synthase on survival of ACC3 cells from salivary adenoid cystic carcinoma

Background

Thymidylate synthase (TS) is an important target for chemotherapeutic treatment of cancer and high expression of TS has been associated with poor prognosis or refractory disease in several cancers including colorectal and head and neck cancer. Although TS is known to regulate cell cycles and transcription factors, its potency as a therapeutic target has not been fully explored in adenoid cystic carcinoma (ACC).

Methods

An ACC cell line (ACC3) was transfected with siRNA targeting the TS gene and inhibition of cell growth and induction of apoptosis-associated molecules were evaluated in vitro. In addition, the in vivo effect of TS siRNA on tumor progression was assessed using a xenograft model.

Results

Our results demonstrated that ACC3 cells showed significantly higher TS expression than non-cancer cell lines and the induction of TS siRNA led to inhibition of cell proliferation. The effect was associated with an increase in p53, p21, and active caspase-3 and S-phase accumulation. We also found up-regulation of spermidine/spermine N1-acetyltransferase (SSAT), a polyamine metabolic enzyme. Furthermore, treatment with TS siRNA delivered by atelocollagen showed a significant cytostatic effect through the induction of apoptosis in a xenograft model.

Conclusion

TS may be an important therapeutic target and siRNA targeting TS may be of potential therapeutic value in ACC.

[18F]2-fluoro-2-deoxy-D-glucose incorporation by AGS gastric adenocarcinoma cells in vitro during response to epirubicin, cisplatin and 5-fluorouracil

Decreased tumour [(18)F]2-fluoro-2-deoxy-D-glucose ((18)FDG) incorporation is related to response however its significance at the cell level in gastro-oesophageal cancer and how it relates to cell death is unknown. Here human gastric adenocarcinoma (AGS) cells were treated with lethal dose 10 and 50 (LD(10) and LD(50)), determined by using the MTT assay, of the three drugs, epirubicin, 5-fluorouracil and cisplatin, commonly used in the treatment of patients with gastro-oesophageal cancer. (18)FDG incorporation was determined after 48 and 72 h of treatment with each drug and related to drug-induced changes in glucose transport, hexokinase activity, cell cycle distribution and annexin V-PE binding (a measure of apoptosis). Treatment of cells for 48 and 72 h with LD(50) doses of cisplatin resulted in reductions in (18)FDG incorporation of 27 and 25% respectively and of 5-fluorouracil reduced (18)FDG incorporation by 34 and 33% respectively: epirubicin treatment reduced incorporation by 30 and 69% respectively. Cells that had been treated for 72 h with each drug were incubated in drug-free media for a further 6 days to determine their ability to recover. Comparison of the ability to recover from the chemotherapy agent, with (18)FDG incorporation before the recovery period allowed an assessment of the predictive ability of (18)FDG incorporation. Cells treated with either 5-fluorouracil or cisplatin demonstrated recovery on removal of the drug. In contrast, cells treated with epirubicin did not recover corresponding with the greatest 72 h treatment decrease in (18)FDG incorporation. In contrast to adherent cells treated with cisplatin or 5-fluorouracil, adherent epirubicin-treated cells also exhibited very high levels of apoptosis. Glucose transport was decreased after each treatment whilst hexokinase activity was only decreased after 72 h of treatment with each drug. There was no consistent relationship observed between (18)FDG incorporation and cell cycle distribution. Our results show that at the tumour cell level in gastric tumour cells, decreased (18)FDG incorporation and glucose transport, accompanies therapeutic growth inhibition. (18)FDG incorporation is particularly diminished in cells exhibiting apoptosis.

Effect of focal adhesion kinase (FAK) downregulation with FAK antisense oligonucleotides and 5-fluorouracil on the viability of melanoma cell lines

Inhibition of focal adhesion kinase (FAK), a non-receptor tyrosine kinase linked to tumour cell survival, causes cell rounding, loss of adhesion and apoptosis in human cancer cell lines. In this study, we tested antisense oligonucleotide inhibitors of FAK, in combination with 5-fluorouracil (5-FU), to increase its sensitivity in human melanoma cell lines. Antisense oligonucleotides directed to the 5' mRNA sequence of FAK and missense control oligonucleotides were used. In BL melanoma cells, treatment with FAK antisense oligonucleotide was associated with a 2.5-fold increase in cell death compared with treatment with control oligonucleotide (33+/-2% vs. 13+/-3%, P<0.0001). 5-FU alone had no effect on BL cells (4.4% cell death, P=0.15). The addition of 5-FU after antisense oligonucleotide resulted in a significant synergistic increase in cell death equal to 69+/-2% compared with treatments with antisense oligonucleotide alone, 5-FU alone and control oligonucleotide (P<0.0001). Similar results were found in the C8161 melanoma cell line. In both cell lines, reduction in cell viability was accompanied by an increased loss of adhesion and increased apoptosis that was proportional to the decrease in viability. Treatment with antisense oligonucleotide plus 5-FU resulted in significantly decreased p125FAK expression in both C8161 and BL melanoma cell lines, demonstrated by Western blot analyses. These data show that the downregulation of FAK by antisense oligonucleotide combined with 5-FU chemotherapy results in a greater loss of adhesion and greater apoptosis in melanoma cells than treatment with either agent alone, suggesting that the combination may be a potential therapeutic agent for human melanoma in vivo.

Bcl-XL small interfering RNA suppresses the proliferation of 5-fluorouracil-resistant human colon cancer cells

5-Fluorouracil (5-FU) is commonly used to treat human colon cancers but resistance to this compound is frequently observed in clinics. To characterize mechanisms of resistance to 5-FU and to develop new strategies for overcoming it, we established two cell lines that were resistant to 5-FU but not other chemotherapeutic agents from parental 5-FU-sensitive cell lines. Western blot analysis revealed that these resistant cells overexpressed the proteins Bcl-XL, Bcl-Xs, and Bik, and further data showed that the cells were resistant to 5-FU-induced DNA damage and cell cycle disorder. However, in parental cells, enforced expression of Bcl-XL protein provided only limited protection from 5-FU-induced apoptosis and overexpression of Bcl-XL protein did not affect 5-FU-induced DNA damage or cell cycle changes; these findings suggested that overexpression of Bcl-XL protein was not the major contributor to 5-FU resistance in any of our cells lines. Even so, knockdown of Bcl-XL protein expression by Bcl-XL-specific small interfering RNA could inhibit proliferation more effectively in 5-FU-resistant cells than in 5-FU-sensitive cells, and the combination of Bcl-XL-specific small interfering RNA and 5-FU had additive effect on the inhibition of 5-FU-resistant cells. These results suggest that down-regulation of Bcl-XL protein expression might provide a new treatment strategy for human 5-FU-resistant colon cancer therapy.

Does cisplatin (CDDP) function as a modulator of 5-fluorouracil (5-FU) antitumor action? A study based on a clinical trial

OBJECTIVE

To clarify whether CDDP acts as a modulator of 5-FU antitumor action in gastric cancer, patients were treated preoperatively with 5-FU + CDDP (FP) chemotherapy.

PATIENTS AND METHODS

From September 2000 to November 2001 at Takarazuka Municipal Hospital, 29 patients preoperatively diagnosed with stages II-IV gastric cancer were enrolled. Written informed consent was obtained from all patients. The patients were randomly assigned to two groups: the FU group, in which patients received a continuous intravenous infusion of 5-FU 320 mg/m2 per day over 24 h a day for 5 days beginning 5 days prior to surgery, and the FP group, in which patients received bolus intravenous injections of CDDP 3.5 mg/m2 per day for 5 days prior to surgery in addition to the same infusion of 5-FU as the FU group. As indicators of the intracellular effect of 5-FU treatment, thymidylate synthase (TS) inhibition rates, TS protein levels, TS and dihydropyrimidine dehydrogenase (DPD) activity, and F-RNA concentrations were measured.

RESULTS

Using Scheffe's multiple comparison test, in both treatment groups the tumor regions were found to have significantly higher TS inhibition rates than the nontumor regions (P<0.05). No significant differences in TS protein levels, TS activity, DPD activity or F-RNA concentrations were found between the four regions.

CONCLUSIONS

Our results show that CDDP clinically may act to enhance the antitumor effects of 5-FU in terms of the inhibition of DNA synthesis and could therefore act as a modulator of 5-FU.

Cell-cycle arrest in Jurkat leukaemic cells: a possible role for docosahexaenoic acid

Docosahexaenoic acid (DHA) is known to have anti-cancer activities by mechanisms that are not well understood. In the present study, we test one possible pathway for DHA action in Jurkat leukaemic cells. Low doses of DHA (10 microM) are shown to induce cell-cycle arrest, whereas higher doses are cytotoxic. However, when cells that were pre-treated with 10 microM DHA are given an additional 10 microM DHA dose, cell viability rapidly decreases. Immunoblotting reveals that repeated low doses of DHA results in activation of caspase 3, implying induction of apoptosis. DHA (10 microM) is shown to increase ceramide levels after 6 h of incubation and, after 24 h, the cells appear to be arrested in S phase. With DHA, the amount of phosphorylated retinoblastoma protein (pRb) decreases significantly. Western blot analysis also shows that DHA greatly reduces the level of cyclin A, while increasing the level of p21 WAF1, a cellular inhibitor of cyclin A/cyclin-dependent kinase 2 (cdk2) activity. Furthermore, the observed DHA-induced doubling of the ratio of hypophosphorylated pRb (hypo-pRb) to total pRb is inhibited by tautomycin and phosphatidic acid (PA), known inhibitors of protein phosphatase 1 (PP1), and by the PP2 inhibitor okadaic acid. The present study demonstrates one possible connected pathway for DHA action. By this pathway, low doses of DHA increase ceramide levels, which leads to inhibition of cdk2 activity and stimulation of PP1 and PP2A. The net effect of cdk2 inhibition and protein phosphatase activation is an inhibition of pRb phosphorylation, consequently arresting Jurkat cell growth.

Selective induction of colon cancer cell apoptosis by 5-fluorouracil in humans

To assess the mechanism of action of 5-fluorouracil (5-FU) apoptosis (AI) and proliferation (PI) indices were determined histochemically in colon carcinoma and normal colon tissue of 7 patients treated preoperatively with 5-FU (300 mg/m2/day for 5 days) and 11 controls. 5-Fluorouracil induced apoptosis selectively in malignant colonocytes (AI in 5-FU-group: 0.126 +/- 0.016 [mean +/- SEM] vs. 0.065 +/- 0.012 in controls; P < 0.05), but not in normal colonocytes. 5-Fluorouracil had no effect on the PI of either normal or malignant colonocytes. 5-Fluorouracil-induced apoptosis did not correlate with clinical outcome at 24 months. We conclude that 5-FU: (a) induces apoptosis selectively in colon cancer cells, while it spares the normal colonic mucosa, and (b) has no effect on colonocyte proliferation under the conditions of our protocol. This effect of 5-FU may contribute to its chemotherapeutic activity in human colon cancer.

mdm2-p53 Interaction: lack of correlation with the response to 5-fluorouracil in advanced colorectal cancer

OBJECTIVE

We investigated the relevance of mdm2 and p53 primary tumour expression to the clinical outcome of a consecutive series of advanced colorectal cancer patients treated with a 5-fluorouracil-based chemotherapy.

METHODS

The expression of p53 and mdm2 was analyzed by an immunohistochemical assay in 80 formalin-fixed paraffin embedded primary tumour samples and related to the clinical response to 5-fluorouracil therapy and to the prognosis of the patients. In a subgroup of 46 tumours, the apoptotic index (AI) as determined by the Tunel technique was also assessed.

RESULTS

Nuclear immunostaining of p53 and mdm2 was present in 42 and 30% of the cases, respectively. No correlation was demonstrated between p53 and mdm2 expression (rs = -0.01; p > 0.05). With regard to the clinical outcome, no statistical association was demonstrated among p53 and mdm2 expression, AI, probability of clinical response to treatment, time to progression, or overall survival. The subgroup of patients with a p53-negative/mdm2-positive tumour showed a worse response rate (15%); however, mdm2-positive/AI-negative tumours showed a 0% (0/7) probability of a clinical response as compared with 30% (9/30) of the remaining tumour patient subgroups; this also translated in a significantly worse overall survival probability (p = 0.01 by log rank).

CONCLUSIONS

The analysis of mdm2 expression does not add significant clinical information in colorectal cancers with a different p53 status. Conversely, further analysis of AI seems to give data of a promising prognostic-predictive value.

Extracellular nucleotides inhibit growth of human oesophageal cancer cells via P2Y(2)-receptors

Extracellular ATP is known to inhibit growth of various tumours by activating specific purinergic receptors (P2-receptors). Since the therapy of advanced oesophageal cancer is unsatisfying, new therapeutic approaches are mandatory. Here, we investigated the functional expression and potential antiproliferative effects of P2-purinergic receptors in human oesophageal cancer cells. Prolonged incubation of primary cell cultures of human oesophageal cancers as well as of the squamous oesophageal cancer cell line Kyse-140 with ATP or its stable analogue ATP gamma S dose-dependently inhibited cell proliferation. This was due to both an induction of apoptosis and cell cycle arrest. The expression of P2-receptors was examined by RT-PCR, immunocytochemistry, and [Ca(2+)](i)-imaging. Application of various extracellular nucleotides dose-dependently increased [Ca(2+)](i). The rank order of potency was ATP=UTP>ATP gamma S>ADP=UDP. 2-methylthio-ATP and alpha,beta-methylene-ATP had no effects on [Ca(2+)](i). Complete cross-desensitization between ATP and UTP was observed. Moreover, the phospholipase C inhibitor U73122 dose-dependently reduced the ATP triggered [Ca(2+)](i) signal. The pharmacological features strongly suggest the functional expression of G-protein coupled P2Y(2)-receptors in oesophageal squamous cancer cells. P2Y(2)-receptors are involved in the antiproliferative actions of extracellular nucleotides. Thus, P2Y(2)-receptors are promising target proteins for innovative approaches in oesophageal cancer therapy.

Tumor vasculature is targeted by the combination of combretastatin A-4 and hyperthermia

BACKGROUND AND PURPOSE

Combretastatin A-4 disodium phosphate (CA-4) enhances thermal damage in s.c. BT(4)An rat gliomas. We currently investigated how CA-4 and hyperthermia affect the tumor microenvironment and neovasculature to disclose how the two treatment modalities interact to produce tumor response.

METHODS

By confocal microscopy and immunostaining for von Willebrand factor, we examined the extent of vascular damage subsequent to CA-4 (50 mg/kg) and hyperthermia (waterbath 44 degrees C, 60 min). The influence on tumor oxygenation was assessed using interstitial pO(2)-probes (Licox system) and by immunostaining for pimonidazole. We examined the direct effect of CA-4 on the tumor cell population by flow cytometry (cell cycle distribution) and immunostaining for beta-tubulin (cytoskeletal damage).

RESULTS

Whereas slight vascular damage was produced by CA-4 in the BT(4)An tumors, local hyperthermia exhibited moderate anti-vascular activity. In tumors exposed to CA-4 3 h before hyperthermia, massive vascular damage ensued. CA-4 reduced the pO(2) from 36.1 to 17.6 mmHg (P=0.01) in the tumor base, and tumor hypoxia increased slightly in the tumor center (pimonidazole staining). Extensive tumor hypoxia developed subsequent to hyperthermia or combination therapy. Despite a profound influence on beta-tubulin organization in vitro, CA-4 had no significant effect on the cell cycle distribution in vivo.

CONCLUSION

Our results indicate that the anti-vascular activity exhibited by local hyperthermia can be augmented by previous exposure to CA-4.

Expression of apoptosis-related markers and clinical outcome in patients with advanced colorectal cancer

The clinical relevance of bax and bcl-2 protein expression has been investigated in 84 patients with recurrent or metastatic colorectal cancer submitted to a chemotherapy regimen including methotrexate and fluorouracil/leucovorin. Cytoplasmic immunostaining of bax and bcl-2 was present in 65.5% and 38%, respectively, of the tumours. No association was found between bax and bcl-2 or between p53 and bax or bcl-2 protein expression. Moreover, the biomarkers were unrelated to patient and tumour characteristics known to affect the clinical outcome of colorectal cancer patients. In general, the apoptosis-related markers did not appear indicative of short- and long-term clinical response nor of prognosis. Bcl-2-negative lesions were more frequent among patients who reached an objective clinical response, which is in agreement with previously reported data regarding other tumour types. When the interrelationship between p53 and bax expression was examined, a better response rate (40%) was found for patients whose tumours did not express p53 and bax, and a better prognosis (2-year probability of overall survival 75%) for patients with p53-positive and bax-negative tumours. In the present series of patients with advanced colorectal cancer submitted to systemic chemotherapy we did not find a clear association between expression of apoptosis-related markers and clinical outcome, even in the subset of patients in which the apoptotic index as determined by the TUNEL approach was investigated.

Preoperative treatment with tegafur suppositories enhances apoptosis and reduces the intratumoral microvessel density of human colorectal carcinoma

BACKGROUND

This study examined the effect of tegafur, a depot of 5-fluorouracil, in human colorectal carcinomas in terms of apoptosis, cell proliferation, and expression of p53 gene and angiogenesis-related molecules.

METHODS

A total of 32 patients with colorectal carcinoma were divided into 2 groups; 20 patients received tegafur suppositories (TS) at 1 g/day for 14 days before surgery, and 12 patients did not receive any chemotherapy. Surgically removed specimens were examined immunohistochemically for Ki-67, CD34, p53, p21, Bax, vascular endothelial growth factor (VEGF), and thymidine phosphorylase (dThdPase). Apoptotic tumor cells were visualized by the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-digoxigenin nick-end labeling (TUNEL) procedure.

RESULTS

The mean percentage of apoptotic index (AI) was 6.9 +/- 1.2 in the 20 TS-treated tumors and 4.4 +/- 1.0 in the 12 nontreated tumors (P < 0.001). In contrast, the mean percentage of Ki-67 labeling index (KI) became significantly lower in the former group (P < 0.05). The frequency of p21 expression was significantly higher in the TS-treated group than in the nontreated group (P < 0.05), whereas no difference was detected in p53 and Bax expression between the two groups. The mean intratumoral microvessel density was 47.8 +/- 19.8 in the TS-treated tumors and 66.8 +/- 16.5 in the nontreated tumors (P < 0.01). The frequency of dThdPase expression, but not of VEGF expression, became significantly lower with the TS treatment. p53 expression did not correlate with AI, KI, IMV density, or the expression of VEGF, p21, or Bax, except for dThdPase, which was significantly higher in the 18 p53 positive tumors (P < 0.05).

CONCLUSIONS

Preoperative TS treatment enhances apoptosis and suppresses angiogenesis of colorectal carcinomas in a p53-independent manner.