Biologic characteristics of the side population of human small cell lung cancer cell line H446.

BACKGROUND AND OBJECTIVE: Recently, the theory of cancer stem cells (CSCs) has presented new targets and orientations for tumor therapy. The major difficulties in researching CSCs include their isolation and purification. The aim of this study is to identify and characterize the side population (SP) cells in small cell lung cancer (SCLC) cell line H446, which lays the foundation for the isolation and purification of CSCs. METHODS: Fluorescence-activated cell sorting (FACS) was used to sort SP and non-SP (NSP) cells from H446. Both subgroups were cultivated to survey the capacity to form into suspended tumor cell spheres. Reverse transcription-polymerase chain reaction (RT-PCR) and real-time PCR were used to evaluate the expression levels of the mRNA of CD133, ABCG2, and nucleostemin in both subgroups. The capacity of proliferation and the differences in drug resistance of both subgroups and unsorted cells were tested by the MTT method. The differentiation ability of both subgroups was determined by FACS. Proliferation was determined by subcutaneous tumor formation in nude mice. RESULTS: The percent of Hoechst 33342 negative cells was about (5.1 +/- 0.2)% in H446 by fluorescence microscopy. The percent of SP cells was (6.3 +/- 0.1)% by flow cytometry. SP cells had a stronger capability of forming into tumor spheres than NSP cells. The mRNA expression levels of ABCG2, CD133, and nucleostemin in SP cells were 21.60 +/- 0.26, 7.10 +/- 0.14, and 1.02 +/- 0.08 folds higher than that in NSP cells (P < 0.01, P < 0.01, and P > 0.05, respectively). In vivo, SP cells showed better proliferative ability and tougher viability when treated with drugs. SP cells can differentiate into NSP cells, but NSP cells cannot differentiate into SP cells. SP cells had a greater ability to form tumors. CONCLUSION: The H446 cell line contained some SP cells with stem cell properties. CD133 and ABCG2 may be cancer stem cell markers of SCLC.

Induction chemotherapy followed by concurrent chemoradiation and nimotuzumab for locoregionally advanced nasopharyngeal carcinoma: preliminary results from a phase II clinical trial.

Overexpression of epidermal growth factor receptor can be found in more than 80% of patients with locoregionally advanced nasopharyngeal carcinoma and is associated with shorter survival. In this work, we evaluated the feasibility of adding nimotuzumab to chemoradiation in locoregionally advanced nasopharyngeal carcinoma. Twenty-three patients with clinically staged T3-4 or any node-positive disease were enrolled. They were scheduled to receive one cycle of induction chemotherapy followed by intensity-modulated radiotherapy, weekly administration of nimotuzumab and concurrent chemotherapy. Results showed that all patients received a full course of radiotherapy, 19(82.6%)patients completed the scheduled neoadjuvant and concurrent chemotherapy, and 22(95.7%) patients received ≥6 weeks of nimotuzumab. During the period of concurrent chemoradiation and nimotuzumab, grade 3-4 toxicities occurred in 14(60.9%) patients: 8 (34.8%) had grade 3-4 oral mucositis, 6(26.1%) had grade 3 neutropenia, and 1(4.3%) had grade 3 dermatitis. No acne-like rash was observed. With a median follow-up of 24.1 months, the 2-year progression-free survival and overall survival were 83.5% and 95.0%, respectively. In conclusion, concurrent administration of chemoradiation and nimotuzumab was well-tolerated with good compliance. Preliminary clinical outcome data appear encouraging with favorable normal tissue toxicity results comparing with historical data of concurrent chemoradiation plus cetuximab.

Krüppel-Like Factor 5 Promotes Epithelial Proliferation and DNA Damage Repair in the Intestine of Irradiated Mice.

BACKGROUND & AIMS: High doses of radiation induce severe DNA damage in intestinal epithelial cells, especially crypt cells, and cause intestinal injury, but the underlying molecular mechanisms remain unclear. Krüppel-like factor 5 (KLF5), a zinc finger-containing transcription factor, is induced by various stress stimuli and is involved in cell proliferation and survival. The role of KLF5 in radiation-induced intestinal injury was investigated here. METHODS: Wild type mice were treated with 8 or 15 Gy total body irradiation (TBI). KLF5 content and cellular localization in the small intestines of irradiated mice were detected by Western blot and immunohistochemical analysis. Mice with intestinal-specific knockdown of KLF5 (Vil-Cre; Klf5(fl/+) mice) were generated and their response to radiation was compared with controls. Morphological changes were determined by hematoxylin and eosin staining. Proliferation was examined by Ki67 immunostaining. The molecular response of the small intestine after KLF5 knockdown was investigated using microarrays. RESULTS: KLF5 expression correlated with the progression of intestinal damage. Decreased levels of KLF5 in the gut were associated with increased damage to the intestinal mucosa and reduced epithelial proliferation after TBI. Our microarray data disclosed that KLF5 knockdown down-regulated genes related to DNA damage repair pathways such as nucleotide excision repair, mismatch repair, non-homologous end joining and the Fanconi anemia pathway, which may suggest a novel function of KLF5. CONCLUSIONS: Our study illustrates that KLF5 may modulate DNA repair pathways to prevent intestinal injury induced by TBI. KLF5 signaling provides a novel field for identification of potential therapeutic targets for the treatment of radiation-induced intestinal damage.

Biological effects of low-dose-rate irradiation of pancreatic carcinoma cells in vitro using 125I seeds.

AIM: To determine the mechanism of the radiation-induced biological effects of 125I seeds on pancreatic carcinoma cells in vitro. METHODS: SW1990 and PANC-1 pancreatic cancer cell lines were cultured in DMEM in a suitable environment. Gray's model of iodine-125 (125I) seed irradiation was used. In vitro, exponential phase SW1990, and PANC-1 cells were exposed to 0, 2, 4, 6, and 8 Gy using 125I radioactive seeds, with an initial dose rate of 12.13 cGy/h. A clonogenic survival experiment was performed to observe the ability of the cells to maintain their clonogenic capacity and to form colonies. Cell-cycle and apoptosis analyses were conducted to detect the apoptosis percentage in the SW1990 and PANC-1 cells. DNA synthesis was measured via a tritiated thymidine (3H-TdR) incorporation experiment. After continuous low-dose-rate irradiation with 125I radioactive seeds, the survival fractions at 2 Gy (SF2), percentage apoptosis, and cell cycle phases of the SW1990 and PANC-1 pancreatic cancer cell lines were calculated and compared. RESULTS: The survival fractions of the PANC-1 and SW1990 cells irradiated with 125I seeds decreased exponentially as the dose increased. No significant difference in SF2 was observed between SW1990 and PANC-1 cells (0.766±0.063 vs 0.729±0.045, P<0.05). The 125I seeds induced a higher percentage of apoptosis than that observed in the control in both the SW1990 and PANC-1 cells. The rate of apoptosis increased with increasing radiation dosage. The percentage of apoptosis was slightly higher in the SW1990 cells than in the PANC-1 cells. Dose-dependent G2/M cell-cycle arrest was observed after 125I seed irradiation, with a peak value at 6 Gy. As the dose increased, the percentage of G2/M cell cycle arrest increased in both cell lines, whereas the rate of DNA incorporation decreased. In the 3H-TdR incorporation experiment, the dosimetry results of both the SW1990 and PANC-1 cells decreased as the radiation dose increased, with a minimum at 6 Gy. There were no significant differences in the dosimetry results of the two cell lines when they were exposed to the same dose of radiation. CONCLUSION: The pancreatic cancer cell-killing effects induced by 125I radioactive seeds mainly occurred via apoptosis and G2/M cell cycle arrest.

CT-guided interstitial brachytherapy of inoperable non-small cell lung cancer.

PURPOSE: The aim of this study was to assess the technical feasibility, efficacy, and complications of CT-guided interstitial brachytherapy for treating inoperable non-small cell lung cancer (NSCLC). MATERIALS AND METHODS: Twenty one patients were included in this prospective study. The median age was 72.6 years (57-85). Tumors were treated with brachytherapy that was positioned under CT-fluoroscopy. The treatment planning system (TPS) was used preoperatively to reconstruct three dimensional images of the tumor and to calculate the estimated seed number and distribution. The median matched peripheral dose (MPD) was 130 Gy (range, 100-160 Gy). All procedures were performed under local anesthesia. A follow-up CT was performed 6 weeks later and every 3 months post implantation. RESULTS: Follow-up period was 2-30 months. The mean diameter of the 21 lung tumors was 4.6 cm (range, 2.8-6.5 cm). The response rate of pain relief was 83.3% (10/12). The pain-free duration was 0-12 months (median: 6 months; 95% CI: 3-9 months). Overall responding rate (CR+PR) for this group of patients was 71.4%. Local tumor control rate was 85.7%. Six (28.6%) patients died as a result of primary tumor progression; thirteen (61.9%) patients died of multi-organ failure or other metastases. Two (9.5%) patients survived to follow-up. At the time of analysis, the median survival time for all patients was 10 months (95% CI: 6.6-13.4 months), with 1 year and 2 year survival rates were 42.4% and 6.5%, respectively. Median survival time for stage II, stage III, and stage IV was 20 months, 9 months, and 8 months, respectively. No major complications were observed. Minor complications (19%) included mild pneumothorax (n=1), hemosputum (n=1), pleural effusion (n=1), and localized skin erythema (n=1). None of these complications required further treatment, although hospital discharge was delayed. No (125)I seeds migrated to other tissues or organs. CONCLUSION: Minimally invasive CT-guided interstitial brachytherapy is safe, useful, less complicated and considered as a palliative treatment option for inoperable non-small cell lung cancer.

[Anti-CD20 monoclonal antibody RTX enhances radiosensitivity of lymphoma cells].

This study was aimed to investigate the effects of rituximab (RTX), a chimeric human anti-CD20 monoclonal antibody, on lymphoma cell injury induced by X ray irradiation. The human Burkitt EBV-infected and moderate radioresistance lymphoma cells (Namalwa) were used in the this study. Cytotoxicity of rituximab combined with X ray irradiation on Namalwa cells was measured by sulforhodamine B (SRB)-staining; the apoptosis of Namalwa cells was detected by flow cytometry with FITC-Annexin V/PI double staining; the morphologic changes of cells were observed under transmission electron microscope (TEM) and the change of intracellular free calcium level ([Ca(2+)]i) in response to irradiation and rituximab was determined by means of the fluorescent dye fluo-3 and confocal microscopy. The results showed that the growth inhibition in Namalwa cells exposed to irradiation was enhanced by treatment with rituximab. Compared with irradiation alone, rituximab combined with irradiation significantly induced the cell apoptosis and a sustained rise of intracellular free calcium ([Ca(2+)]i) level in Namalwa cells; the serial apoptotic appearances of cells could be observed under TEM. It is concluded that rituximab can enhance the sensitivity of lymphoma cells on X ray irradiation as to induce cell more apoptosis, in this process the intracellular free calcium ([Ca(2+)]i), as an intracellular signaling molecule probably plays an important role.