Treatment with 5-fluorouracil enhances radiosensitivity of the human pancreatic cancer cell line MiaPaCa-2

Pharmacological Ascorbate Enhances Chemotherapies in Pancreatic Ductal Adenocarcinoma

OBJECTIVES

Pharmacological ascorbate (P-AscH - , high-dose, intravenous vitamin C) has shown promise as an adjuvant therapy for pancreatic ductal adenocarcinoma (PDAC) treatment. The objective of this study was to determine the effects of P-AscH - when combined with PDAC chemotherapies.

METHODS

Clonogenic survival, combination indices, and DNA damage were determined in human PDAC cell lines treated with P-AscH - in combination with 5-fluorouracil, paclitaxel, or FOLFIRINOX (combination of leucovorin, 5-fluorouracil, irinotecan, oxaliplatin). Tumor volume changes, overall survival, blood analysis, and plasma ascorbate concentration were determined in vivo in mice treated with P-AscH - with or without FOLFIRINOX.

RESULTS

P-AscH - combined with 5-fluorouracil, paclitaxel, or FOLFIRINOX significantly reduced clonogenic survival in vitro. The DNA damage, measured by γH2AX protein expression, was increased after treatment with P-AscH - , FOLFIRINOX, and their combination. In vivo, tumor growth rate was significantly reduced by P-AscH - , FOLFIRINOX, and their combination. Overall survival was significantly increased by the combination of P-AscH - and FOLFIRINOX. Treatment with P-AscH - increased red blood cell and hemoglobin values but had no effect on white blood cell counts. Plasma ascorbate concentrations were significantly elevated in mice treated with P-AscH - with or without FOLFIRINOX.

CONCLUSIONS

The addition of P-AscH - to standard of care chemotherapy has the potential to be an effective adjuvant for PDAC treatment.

Superior Effect of the Combination of Carbon-Ion Beam Irradiation and 5-Fluorouracil on Colorectal Cancer Stem Cells in vitro and in vivo

Background

The aim of this study was to investigate whether carbon-ion beam irradiation in combination with 5-fluorouracil (5-FU) is superior to carbon-ion beam irradiation alone in targeting colorectal cancer stem-like cells (CSCs).

Materials and Methods

Human colorectal cancer (CRC) cells, HCT116 and HT29, were treated with carbon-ion beam irradiation alone or in combination with 5-FU. Cell viability assay, colony and spheroid formation assay, apoptotic assay, and quantitative real-time PCR analysis of apoptosis- and autophagy-related gene expression were performed.

Results

Carbon-ion beam irradiation dose-dependently decreased CRC cell viability and showed significantly enhanced cell killing effect when combined with 5-FU. Carbon-ion beam irradiation in combination with 5-FU significantly increased the percentage of apoptotic cells. The expression of some apoptotic and autophagy-related genes such as Bax, Bcl2, Beclin1 and ATG7 was significantly induced by carbon-ion beam irradiation alone and was further enhanced when the beam was combined with 5-FU. The spheroid forming capacity of CD133+ cell subpopulations was significantly inhibited by carbon-ion beam in combination with 5-FU. Histopathologically, the combination of carbon-ion beam irradiation and 5-FU destroyed more xenograft tumor cells, and resulted in increased necrosis, cavitation, and fibrosis, compared to carbon-ion beam irradiation alone.

Conclusion

In conclusion, carbon-ion beam treatment combined with 5-FU has the potential to kill CRC cells including CSCs by inducing increased apoptosis and autophagy.

Keys to successful induction chemoradiotherapy followed by surgery for stage III/N2 non-small cell lung cancer

Surgical intervention after induction chemoradiation is designed as curative treatment for resectable stage III/N2 non-small cell lung cancer. However, there is no definitive evidence to support this approach, possibly because successful treatment requires certain "arts", such as proper patient selection, an appropriate induction regimen, and choice of the best surgical procedure. We review the previous reports and discuss our own experience to explore the appropriate strategy for patients with resectable stage III/N2 disease, and to identify the factors associated with successful surgical intervention. Among the studies reviewed, the complete resection rate among intention-to-treat cases was correlated well with the 5-year survival rate, whereas the pneumonectomy rate was correlated inversely with the 5-year survival rate. The clinical response rate and downstaging after induction treatment were not associated with survival. Based on these findings, we conclude that complete resection with the avoidance of pneumonectomy is important when selecting candidates for multimodal treatment including radical surgery.

In vitro radiosensitization by oxaliplatin and 5-fluorouracil in a human colon cancer cell line

The current study was designed to compare the radiosensitizing effects of oxaliplatin and 5-fluorouracil (5FU) in a human colon cancer cell line. A human colon cancer cell line (S1) was treated with various doses of oxaliplatin, 5FU, radiation, and combinations thereof. Various clinically used schedules were mimicked. 5FU was either incubated during 1 h ("bolus") or 24 h ("continuous infusion"). When combining oxaliplatin and 5FU, an isobologram analysis revealed synergistic effects, regardless of 5FU schedule. The IC(10) and IC(50)-doses for the drugs where then combined with radiotherapy. With equitoxic drug doses (IC(50)), radiosensitization was observed in the following order: oxaliplatin > 5FU 24 h > 5FU 1 h exposure. The degree of potentiation corresponded to approximately 0.8 Gy, 0.7 Gy, and 0.2 Gy, respectively. In this experimental setting, oxaliplatin seemed to be a better radiosensitizer than 5FU, and longer incubation time with 5FU was better than short exposure.

Chemoradiotherapy in patients with pancreatic carcinoma: phase-I study with a fixed radiation dose and escalating doses of weekly gemcitabine

AIM

The aim of this phase-I study is to determine the maximum tolerated dose (MTD) of weekly gemcitabine in concurrent combination with a total radiation dose of 54 Gy in patients with pancreatic cancer.

METHODS

In all patients, a total dose of 54 Gy was delivered in 30 fractions of 1.8 Gy/day. Gross tumor volume and regional lymph nodes were included in the irradiated volume with a 1- to 1.5-cm margin. The doses of weekly gemcitabine were escalated from 100 mg/m2 by increments of 50 mg/m2. Dose-limiting toxicity (DLT) was defined as hematologic toxicity, prolonged grade-3 non-hematologic toxicity, and incompletion of the planned treatment.

RESULTS

Twenty-six patients entered the trial. From level 1 (100 mg/m2) to level 4 (250 mg/m2), no patient experienced DLT except for 1 patient at level 1. At level 5 (300 mg/m2), 3 of the 5 patients met the DLT criteria. One patient developed severe pulmonary abscess, and the other 2 patients had hematologic DLT. The overall partial response rate was 29%, and the median survival time was 13.7 months. The first relapse occurred at the in-field primary site in 6 patients and at distant organs in 13 patients.

CONCLUSION

The MTD of weekly gemcitabine was 250 mg/m2 in the present chemoradiotherapy setting. The efficacy of this chemoradiotherapy regimen is currently being evaluated in the phase-II setting.

Combined effects of the oral fluoropyrimidine anticancer agent, S-1 and radiation on human oral cancer cells

We evaluated the orally administered S-1, in combination with ionizing radiation both in vivo and in vitro against human oral cancer cell lines. Human oral cancer cell lines were used as subcutaneous xenografts in nude mice. S-1 (10 mg/kg) was administered orally 1 h before radiation treatments (1.5 Gy), or 1 h after radiation for five consecutive days. Apoptotic cells were detected by TUNEL method. For in vitro analysis, attached cells were treated with S-1 (50 microg/ml) for 1 h and then irradiated (3, 6, 9, 12, 15 Gy), or they were treated with S-1 for 1 h after radiation. Cell survival was determined by clonogenic assay. The combination of S-1 and radiation was more effective than either agent alone. In addition, S-1 administration before radiation was more effective than S-1 administration after radiation. Moreover, the combination of S-1 and radiation could induce apoptosis significantly than either agent alone (P < 0.01). In vitro clonogenic survival experiments demonstrated the dose enhancement ratio of 1.22 (radiation + S-1), 1.45 (S-1 + radiation) in B88 cells, and 1.16 (radiation + S-1), 1.28 (S-1 + radiation) in HSG cells. These data demonstrate that the combination of S-1 and fractionated radiotherapy is more effective against human oral cancer xenografts than either agent alone, and that S-1 administration before radiation is more effective than after radiation, suggesting a potential clinical applicability of combination treatment of S-1 and radiation in oral cancer therapies.

Reduced late asthmatic response by repeated low-dose allergen exposure

Allergic asthmatic individuals are often exposed to low-doses of allergen in their everyday life. Extended exposure to allergen has lead to down-regulation of the allergic process in cell systems and in animal models. The aim of this study was to evaluate whether any such inhibitory mechanism of allergic responses can be seen in man in vivo. Patients with mild asthma were repeatedly and double-blindly exposed to 25% of the individual dose of allergen that caused an early (EAR) and late asthmatic reaction (LAR). One day after the low-dose allergen or placebo exposure periods, the same individual was given a high-dose allergen challenge. Sputum and blood were collected for the evaluation of eosinophils. Exposure to repeated low doses of allergen induced increased bronchial methacholine responsiveness 6 h after the final allergen exposure (p=0.018), and an increase in the number of eosinophils in sputum. By contrast, the late asthmatic response after challenge with a high dose of allergen was significantly attenuated by approximately 30% at 24 h after the final low-dose allergen exposure (p = 0.03). In summary, repeated low doses of allergen given directly to the airways, attenuate the high-dose allergen-induced late response, despite enhanced bronchial hyperresponsiveness to methacholine and elevated sputum eosinophils prior to allergen challenge.