Effect of preoperative 5-fluorouracil on apoptosis of advanced gastric cancer

Autophagy inhibition enhanced 5‑FU‑induced cell death in human gastric carcinoma BGC‑823 cells

The exact molecular mechanism of 5-fluorouracil (5-FU) in human gastric cancer cells remains to be elucidated. Cultured BGC‑823 human gastric carcinoma and AGS cell lines were treated with 5‑FU. Autophagosome formation was investigated through multiple approaches, including the quantification of green fluorescent protein‑microtubule‑associated protein 1A/1B‑light chain 3 (LC3) puncta, LC3 conversion and electron microscopy observations. Additionally, autophagy was inhibited using 3‑methyladenine (3‑MA) and beclin‑1 ablation, to determine its role in 5‑FU‑mediated cell death. In addition, the present study assessed alterations in sirtuin expression following 5‑FU treatment with reverse transcription‑quantitative polymerase chain reaction. 5‑FU treatment induced apoptosis and inhibited proliferation in BGC‑823 and AGS gastric cancer cells. It is of note that the 5‑FU treatment only promoted autophagy in BGC‑823 cells. Additionally, inhibition of autophagy by either 3‑MA or beclin‑1 ablation increased 5‑FU‑induced cell death in BGC‑823 cells. The present study quantified changes in sirtuin (SIRT1, SIRT3, SIRT5, and SIRT6) expression following 5‑FU treatment and using a specific inhibitor, sirtinol, the present study investigated their involvement in 5‑FU‑mediated autophagy. Autophagy inhibition through manipulation of sirtuin proteins may increase the therapeutic efficacy of the 5‑FU chemotherapeutic drug against gastric carcinoma.

[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.

5-Fluorouracil Mediates Apoptosis and G1/S Arrest in Laryngeal Squamous Cell Carcinoma via a p53-Independent Pathway

PURPOSE

5-Fluorouracil (5-FU) is a commonly used chemotherapeutic agent in the treatment of laryngeal squamous cell carcinoma. 5-FU can induce cell cycle arrest or apoptosis in various cancers via either a p53-dependent or a p53-independent pathway; however, its pathway of action in laryngeal carcinoma is unknown. In this study, we aim to investigate the role that p53 plays in the cytotoxic effect of 5-FU on laryngeal squamous carcinoma cells.

MATERIALS AND METHODS

We employed two human laryngeal squamous carcinoma cell lines with different p53 statuses-one (UMSCC12) had truncated non-functional p53 and the other (UMSCC11A) had mutant but functional p53. Cell death was detected using cytotoxicity assay and Annexin V staining. Cell cycles were analyzed by flow cytometry. Western blot was used to analyze the protein expression.

RESULTS

5-FU induces apoptosis in both UMSCC12 and UMSCC11A cells in a dose- and time-dependent manner, suggesting that the pathway was p53-independent. 5-FU induced the accumulation of retinoblastoma protein and a cyclin dependent kinase inhibitor, p21WAF1/CIP1, in both UMSCC12 and UMSCC11A cells. However, 5-FU did not induce p53 expression in either UMSCC12 or UMSCC11A cells. In addition, G1/S cell cycle phase arrest was associated with antiproliferative activity of 5-FU in both cell lines. In order to gain an insight into the role p53 plays in response to 5-FU treatment in laryngeal carcinoma, we further transfected either a wildtype p53 plasmid or an empty pcDNA3.1 vector into UMSCC12 cells. We found that 5-FU increased pRb and p21WAF1/CIP1 expression in both p53-transfected and vector-transfected cells without the significant accumulation of p53.

DISCUSSION

Our results suggest that 5-FU mediates apoptosis and G1/S cell cycle phase arrest in laryngeal carcinoma via a p53-independent but p21WAF1/CIP1-dependent or p21WAF1/CIP1-Rb-dependent pathway. While p53 does not seem to be involved in 5-FU induced apoptosis and cell cycle arrest in laryngeal carcinoma, further studies are needed to examine the roles of retinoblastoma protein and p21WAF1/CIP1 in laryngeal carcinoma receiving chemotherapy.

Apoptosis induced by preoperative oral 5’-DFUR administration in gastric adenocarcinoma and its mechanism of action

AIM: To study the apoptosis induced by preoperative oral 5’-DFUR administration in gastric adenocarcinoma and its mechanism of action.

METHODS: Sixty gastric cancer patients were divided randomly into three groups (20 each group) before operation: group one: 5’-DFUR oral administration at the dose of 800-1200mg/d for 3 - 5 d, group two: 500mg 5-FU + 200 mg/d CF by venous drip for 3 - 5 d, group three (control group). One or two days after chemotherapy, the patients were operated. Fas/FasL, PD-ECGF and PCNA were examined by immunohistochemistry and apoptotic tumor cells were detected by in situ TUNEL method. Fifty-four patients received gastrectomy, including 12 palliative resections and 42 radical resections. Six patients were excluded. Finally 18 cases in 5’-DFUR group, 16 cases in CF + 5-FU group, and 20 cases in control group were analyzed.

RESULTS: There was no significant difference in patient mean age, gender, white blood cell count, haematoglobin (HB), thromboplastin, perioperative complication incidence, radical or palliation resection, invasion depth (T), lymphonode involvement (N), metastasis (M) and TNM staging among the three groups. However, the PCNA index (PI) in 5’-DFUR group (40.51 ± 12.62) and 5-FU + CF group (41.12 ± 15.26) was significantly lower than that in control group (58.33 ± 15.69) (F = 9.083, P = 0.000). The apoptotic index (AI) in 5’-DFUR group (14.39 ± 9.49) and 5-FU + CF group (14.11±9.68) was significantly higher than that in control group (6.88 ± 7.37) (F = 4.409, P = 0.017). The expression rates of Fas and FasL in group one and group three were 66.7% (12/18) and 50% (9/18), 43.8% (7/16) and 81.3% (13/16), 45.0% (9/20) and 85% (17/20), respectively. The expression rate of FasL in 5’-DFUR group was significantly lower than that in the other two groups (χ²=6.708, P = 0.035). Meanwhile, the expression rate of PD-ECGF was significantly lower in 5’-DFUR group (4/18，28.6%) than in CF + 5-FU group（9/16，56.3%）and control group (13/20，65.0%) (χ²= 7.542, P = 0.023). The frequency of Fas expression was significantly correlated with palliative or radical resection (χ²= 7.651, P = 0.006), invasion depth (χ²= 8.927, P = 0.003), lymphatic spread (χ²= 4.488, P = 0.034) and UICC stages (χ²= 8.063, P = 0.045) respectively. By the end of March 2005, 45 patients were followed up. The 0.5-, 1-, 2-, 3-year survival rates were 96%，73%，60%，48%, respectively, which were related with T, N, M and Fas expression, but not with PD-ECGF and FasL expression.

CONCLUSION: Preoperative oral 5’-DFUR administration may induce apoptosis of gastric carcinoma cells and decrease tumor cell proliferation index, but cannot improve the prognosis of patients with gastric cancer. Down-regulation of FasL and PD-ECGF expression mediated by 5’-DFUR may be one of its anti-cancer mechanisms. Fas expression correlates with the progression of gastric carcinoma and may be an effective prognostic factor.

A new animal model of continuous catheterization for investigating mechanisms of arteritis associated with chemotherapy

Although superselective continuous intra-arterial infusion has advantages for cancer therapy, intra-arterial chemotherapy is often interrupted by arterial damage due to arteritis. Therefore, an animal model must be developed to elucidate the mechanism of arteritis associated with continuous anti-cancer drug infusion. We developed a new rat model with which to investigate the causal mechanism(s) of vascular damage associated with continuous catheterization chemotherapy. Chemotherapeutic agents (fluorouracil (5-FU) or peplomycin (PEP)) were continuously administered for 7 days into the abdominal aorta of male Sprague-Dawley rats through a catheter fixed in situ. We found that the incidence of apoptotic endothelial cells of the aorta was higher nearer the tip of the catheter. The incidence of apoptosis was higher in the group treated with 5-FU than with PEP. This animal model will be useful to improve arterial damage among patients undergoing chemotherapy using continuous catheterization.

Prognostic use of growth characteristics of early gastric cancer and expression patterns of apoptotic, cell proliferation, and cell adhesion proteins

BACKGROUND AND OBJECTIVES

Selection of suitable treatment for early gastric cancers, such as endoscopic mucosal resection or the major surgical option of resection of the cancer together with a radical lymph node dissection, may be assisted by comparing the growth characteristics of the cancer with selected molecular characteristics. The results could be used to predict those cases that have a higher risk of developing secondary metastases.

METHODS

A total of 1,196 Japanese patients with early gastric cancers (648 mucosal cancers and 548 submucosal) were included in the selection of two groups: a metastatic group made up 57 cancers with lymph node metastasis (9 mucosal, 48 submucosal), and a nonmetastatic group of 61 cases (6 mucosal, 55 submucosal) without lymph node metastasis. Growth characteristics of the cancers (superficially spreading, penetrating or invasive, lymph node metastasis) were compared with immunohistochemical expression of single-stranded DNA (ssDNA) protein (apoptosis indicator), bcl-2 and p53 (apoptosis-associated), Ki-67 (cell proliferation), and E-cadherin (cell adhesion) proteins.

RESULTS

The lesions in the nonmetastatic group had higher levels of apoptosis and lower expression of bcl-2 than in the metastatic group, indicating an inhibitory role for apoptosis in malignant progression. Apoptosis was also higher in the superficial compared with the invasive lesions of both groups. The lesions in the metastatic group had higher p53 expression than that of the nonmetastatic group, whereas apoptosis in the metastatic group was lower than in the nonmetastatic group. An unproved explanation for this finding may be that, although increased, p53 was mutated and ineffective in promoting apoptotic control of metastatic progression. E-cadherin was decreased in the invasive lesions of both groups, indicating a greater ability of these cells to lose adhesion, to invade the submucosa, and to metastasize. Cell proliferation was highest in the superficial lesions of both metastatic and nonmetastatic groups.

CONCLUSIONS

Early gastric cancers with low levels of apoptosis, increased bcl-2, and high levels of p53 expression are more likely to invade and metastasize.

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.

Ligand activation of alternatively spliced fibroblast growth factor receptor-1 modulates pancreatic adenocarcinoma cell malignancy

Pancreatic adenocarcinoma continues to be a devastating tumor (28,000 new cases per year in the United States; 10% 2-year survival). Pancreatic adenocarcinoma frequently (90% of the time) overexpresses fibroblast growth factor ligands (FGF-1 and FGF-2) and alternatively spliced high-affinity receptors (FGFR-1beta) (FGFR-1alpha was previously found in normal pancreatic tissue). To study the significance of this observation in vitro, PANC-1 cells were stably transfected via the pMEXneo vector containing FGFR-1alpha (PANC-1alpha) or FGFR-1beta (PANC-1beta) isoforms. Cells were treated with 1 mg/ml of 5-fluorouracil. Cells were evaluated for growth inhibition, apoptosis (propidium iodide staining and flow cytometry, caspase 3 activation) and for Bcl-x(L)/BAX expression (by Western blot analysis). In vivo, 7 x 10(6) cells of each isoform were injected into nude Balb/c mice for xenograft formation (N = 10). Compared to PANC-1beta (9%) in vitro, 5-fluorouracil-induced death was significantly (P < 0.05) increased in PANC-1alpha (20%) at 24 hours. Increased cell death in PANC-1alpha was mediated by activated caspase 3 and was correlated with decreased expression of Bcl-x(L)/BAX. In vivo, PANC-1beta readily demonstrated formation of tumor xenograft at 2 weeks, whereas PANC-1alpha did not form tumors. Alternative splicing of FGFR-1 to the beta isoform appears to correlate with pancreatic adenocarcinoma cell growth in vivo and resistance to chemotherapy. Inhibition of FGFR-1 splicing or overexpression of FGFR-1alpha inhibits pancreatic adenocarcinoma cell growth in vivo and restores cytotoxic responses to chemotherapy, thereby suggesting the basis of rational interventional strategies for this devastating tumor.

Effect of preoperative regional artery chemotherapy on proliferation and apoptosis of gastric carcinoma cells

AIM: To study the effects of preoperative regional artery chemotherapy (PRACT) in inducing growth inhibition and apoptosis of gastric carcinoma (GC) cells.

METHODS: TUNEL (terminal-deoxynucleotidyl-transferase TdT-mediated dUTP-fluorescein and labeling) method and immunohistochemical techniques were used to detect the state of apoptosis and proliferation of GC cells in histopathologic sections. A total of 110 cases of GC and 68 cases of metastatic lymph node with or without PRACT were adopted. Correlations between apoptosis index (AI), proliferation index (PI) and PRACT and prognosis were analysed.

RESULTS: The apoptosis index (AI) was significantly higher in the PRACT group (12.5‰± 4.33‰) than in the untreated group (7.1‰± 3.43‰, P < 0.001), whereas the proliferation index (PI) in the PRACT group (33.8% ± 8.8%) was significantly lower than that in untreated group (43.6% ± 12.8%, P < 0.01). Both AI and PI were correlated to the differentiation degree of GC in PRACT group, the AI in the differentiated group was higher than that in undifferentiated group (P < 0.001), but the PI was lower in the differentiated group than that of the undifferentiated group (P < 0.01). The AI of GC cells in metastatic lymph node was also significantly higher in the PRACT group (7.9‰± 3.41‰) than in the untreated group (3.6‰± 2.93‰, P < 0.01), though the PI of GC cells in metastatic lymph nodes in the PRACT group (17.2% ± 6.8%) was significantly lower than that in the untreated group (26.7% ± 9.3%, P < 0.01). The severity of histopathologic changes was significantly higher in the PRACT group than in the untreated group (P < 0.05). In addition, postoperative surveys demonstrated that the 5-year survival rate of GC patients in the PRACT group was significantly higher than that of patients in the untreated group (P < 0.01).

CONCLUSION: Preoperative regional artery chemotherapy (PRACT) showed inhibitory action on the growth of GC cells mainly through inhibiting proliferation and inducing the apoptosis of tumor cells. PRACT can improve the prognosis of GC patients also.

Spontaneous and inducible apoptosis in oesophageal adenocarcinoma

The use of neoadjuvant chemoradiotherapy prior to surgery in the treatment of oesophageal adenocarcinoma has increased in recent years, and up to 25% of patients will have a complete pathological response to the neoadjuvant therapy. Many patients will not respond, however, and the knowledge of molecular factors predicting response or resistance to chemoradiotherapy is required to enhance treatment results. An understanding of apoptosis and cell proliferation may be relevant and this study focused on apoptotic indices and cell-cycle related (Ki-67, p53 and bcl-2) protein expression in a cohort of 42 patients with primary oesophageal adenocarcinoma. We documented that apoptosis occurs among viable (proliferating) tumour cells in all adenocarcinoma cases examined in this study. Pre-operative chemoradiotherapy significantly increased apoptosis and significantly decreased cell proliferation (estimated by Ki-67 expression). Immunohistochemically detected p53 and bcl-2 gene products had no regulatory role in the apoptotic process. The cumulative expression of p53 protein is significantly associated with increasing proliferation activity. Evaluation of apoptosis in pre-treatment specimens may have potential utility in predicting the efficacy of treatment. Assessment of the tumours proliferation activity by Ki-67 expression might identify patients who are at risk of developing metastatic disease.

Induction of apoptosis by arsenic trioxide and hydroxy camptothecin in gastriccancer cells in vitro

AIM:To study the effects of arsenic trioxide and HCPT on dif ferent degrees of differentiated gastric cancer cells (SGC-7901, MKN-45, MKN-28) with respect to both cytotoxicity and induction of apoptosis in vitro.METHODS:The cytotoxicity of As(2)O(3) and HCPT on gastric cancer cells was det ermined by MTT assay.Morphologic changes of apoptosis of gastric cancer cells were observed by light microscopy and transmission electron microscopy.Apoptosis and cell cycle changes of gastric cancer cells induced by HCPT and As(2)O(3) we re investigated by TUNEL method and flow cytometry.RESULTS:As(2)O(3) and HCPT had remarkable cytotoxic effects on different degrees of differentiated gastric cancer cells. The IC(50) of As(2)O(3) on well differentiated gastric cancer cell MKN-28, moderately differentiated gastric cancer cell SGC-7901, and poorly differentiated gastric cancer cell MKN-28 were 8.91 &mgr;mol/L, 10.57 &mgr;mol/L, and 11.65&mgr;mol/L, respectively. The IC(50) of HCP T on MKN-28, SGC-7901, and MKN-45 were 9.35 mg/L, 10.21 mg/L,and 12.63 mg/L respectively after 48 h treatment. After 12 h of exposure to both drugs, gastric cancer cells exhibited morphologic features of apoptosis, includ ing cell shrinkage,nuclear condensation, and formation of apoptotic bodies. A ty pical subdiploid peak before G(0)/G(1) phase was observed by flow cytometry. The apoptotic rates of SGC-7901, MKN-45, and MKN-28 were 13.84%, 22.52%, and 9.68%, respectively after48 h exposure to 10&mgr;mol/L As(2)O(3). The apoptotic ra tes of SGC-7901, MKN-45, and MKN-28 were 21.88%, 12.35%, and 30.26%, resp ectively after 48 h exposure to 10 mg/L HCPT. The apoptotic indice were 7%-15% a s assessed by TUNEL method. The effect of As(2)O(3) on SGC-7901 showed remarkab le cell cycle specificity, which induced cell death in G(1) phase, and blocked G(2)/M phase.HCPT also showed a remarkable cell cycle specificity, by inducing cell death and apoptosis in G(1) phase and arrest of proliferation at Sphase.CONCLUSION:As(2)O(3) and HCPT exhibit significant cytotoxicity on gastric canc er cells by induction of apoptosis. As(2)O(3) and HCPT might have a promising pr ospect in the treatment of gastric cancer, which needs to be further studied.

5-Fluorouracil-induced apoptosis in cultured oral cancer cells

Chemotherapy is commonly used to treat advanced oral squamous cell carcinoma (SCC) and is known to kill cancer cells through apoptosis. Our hypothesis states that 5-fluorouracil (5FU) also kills cultured oral epithelial cells through programmed cell death or apoptosis. Cultured oral cancer cells were exposed to an optimum dose of 20 mg/ml of 5FU. Cells were analyzed for changes in cell cycle distribution and induction of cell death including apoptosis. Normal control, human papilloma virus-immortalized (PP), ATCC SCC cell line (CA1) and two primary oral SCC cell lines (CA3 and -4) were studied. Inhibition of apoptosis by a pan-caspase inhibitor was used. SYTO 11 flow cytometry showed increased apoptosis in all 5FU-treated cell cultures compared to untreated controls. The results show biological variation in apoptotic response. CA1 had the lowest apoptotic rate of the cancer cell lines at 1.5%. Next lowest was CA3, followed by CA4 and PP. In addition, alteration in the G1 and S phase fractions were found. Untreated CA1 showed 28% G1, 53% S compared to 43% G1, and 40% S of treated. We investigated the pathway of apoptosis using the pan-caspase inhibitor IDN-1529 by methylthiazolyl diphenyl tetrazolium bromide (MTT) colorimetric analysis. Results showed mild inhibition of cell death when cells were incubated with 50 microM IDN-1529 for 24 h. This suggests a probable caspase-dependent apoptotic pathway. In conclusion, our data suggest that 5FU induces oral cancer cell death through apoptosis and that biological variation exists between normal and cancer cells and between different types of cancer cells themselves. Our data indicate that cultures of a useful in vitro model for chemosensitivity assays are possible. Our results also suggest a caspase-dependent pathway for chemocytotoxicity in oral SCC.

Increase in apoptosis and decrease in ornithine decarboxylase activity of the gastric mucosa in patients with atrophic gastritis and gastric ulcer after successful eradication of Helicobacter pylori

OBJECTIVE

Recent reports have shown that patients infected with Helicobacter pylori (H. pylori) have a higher risk of gastric cancer. However, the mechanism of this increased risk is still unclear. In the gastric mucosa, the size of a continuously renewed population of cells is determined by the rates of cell production and of cell loss. Ornithine decarboxylase (ODC) activity is elevated in various gastrointestinal cancers and serves as a marker of mucosal proliferative activity. Apoptosis occurs throughout the gut and is associated with cell loss. Both cell proliferation and cell loss have important roles in H. pylori-associated gastric carcinogenesis. Therefore, we investigated the effect of H. pylori eradication on ODC activity and apoptosis in the gastric mucosa of patients with atrophic gastritis and gastric ulcers.

METHODS

Biopsy specimens of the gastric antrum were obtained at endoscopy from 17 H. pylori-positive gastric ulcers patients and 15 H. pylori-positive gastritis patients before and 4 wk after eradication therapy with amoxicillin, omeprazole, and a new anti-ulcer agent, ecabet sodium, and from 10 gastric ulcer patients in whom ulcer healed but H. pylori was left untreated. ODC activity and induction of apoptosis were determined immunohistochemically.

RESULTS

H. pylori was successfully eradicated with the triple therapy in 12 (80%) of 15 gastritis patients and 13 (76%) of 17 gastric ulcer patients. ODC activity was present in the gastric mucosa in 21 (84%) patients before eradication but in only four (16%) patients after successful eradication (p = 0.0005). The apoptotic index increased significantly (p = 0.0006) from 4.2% +/- 0.4% before treatment to 7.4% +/- 0.5% after successful eradication.

CONCLUSIONS

Successful eradication of H. pylori decreases mucosal ODC activity and increases apoptosis in the gastric mucosa. These findings indicate that by decreasing mucosal cell proliferation and increasing epithelial cell loss, H. pylori eradication may help decrease the subsequent risk of gastric cancer.

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

BACKGROUND

In this study, the authors examined the correlations among enhancement of apoptosis, changes in cell cycle distribution, and expression of Ki-67 in human colorectal carcinoma cells during different durations of preoperative treatment with 5-fluorouracil (5-FU).

METHODS

Forty-one patients with advanced colorectal carcinoma were divided into 4 groups, which received intravenous 5-FU at 500 mg/body/day preoperatively for 3 days (n = 11), 5 days (n = 13), 7 days (n = 9), or 10 days (n = 8). Patients were further divided into two subgroups according to the DNA ploidy pattern of their tumors, i.e., diploid or aneuploid. Apoptotic cells were stained by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) method. The expression of Ki-67 was examined by immunohistochemical staining. Flow cytometry was used to analyze changes in cell cycle distribution.

RESULTS

Apoptosis of cancer cells was mostly increased in the 7-day group (apoptotic index [Al]: 18.3+/-1.7%] compared with that of the 3-day, 5-day (AI: 11.3+/-2.3% and 13.2+/-2.8%, respectively) (P < 0.01), or 10-day (Al: 16.2+/-2.1%) (P < 0.05) groups. The expression of Ki-67 was reduced with increasing prolongation of 5-FU administration, from 55.2+/-2.1% in the 3-day group to 38.1+/-2.7% in the 10-day group. The authors also assessed the S-phase fraction (SPF) of cancer cells to evaluate changes in cell cycle distribution caused by 5-FU. All tumor samples from patients treated by 5-FU showed S-phase accumulation. The ratio of SPF (after 5-FU/before 5-FU) was higher in the 5-day group (2.35+/-0.78) than in the 3-day (1.71+/-0.48), 7-day (1.68+/-0.55), or 10-day (1.20+/-0.20) groups (P < 0.05). DNA ploidy pattern of the tumor had no influence on the enhancement of apoptosis, the increased ratio of SPF, or the decrease in proliferative activity of colorectal carcinoma cells induced by 5-FU.

CONCLUSIONS

S-phase accumulation preceded apoptotic cell death when intravenous 5-FU was administered continuously to human colorectal carcinoma cells.