Akiva Vexler

Reduced Repair of the Oxidative 8-Oxoguanine DNA Damage and Risk of Head and Neck Cancer

An increasing number of studies indicate that reduced DNA-repair capacity is associated with increased cancer risk. Using a functional assay for the removal of the oxidative DNA lesion 8-oxoguanine by the DNA-repair enzyme 8-oxoguanine DNA glycosylase 1 (OGG1), we have previously shown that reduced OGG activity is a risk factor in lung cancer. Here, we report that OGG activity in peripheral blood mononuclear cells from 37 cases with squamous cell carcinoma of the head and neck (SCCHN) was significantly lower than in 93 control subjects, frequency matched for age and gender. Retesting of OGG activity 3 to 4 years after diagnosis and successful treatment of 18 individuals who recovered from the disease showed that OGG activity values were similar to those determined at diagnosis, suggesting that reduced OGG activity in case patients was not caused by the disease. Logistic regression analysis indicated that the adjusted odds ratio (OR) associated with a unit decrease in OGG activity was statistically significantly increased [OR, 2.3; 95% confidence interval (95% CI), 1.5-3.4]. Individuals in the lowest tertile of OGG activity exhibited an increased risk of SCCHN with an OR of 7.0 (95% CI, 2.0-24.5). The combination of smoking and low OGG was associated with a highly increased estimated relative risk for SCCHN. These results suggest that low OGG is associated with the risk of SCCHN, and if confirmed by additional epidemiologic studies, screening of smokers for low OGG activity might be used as a strategy for the prevention of lung cancer and SCCHN.

Fibrin Microbeads for Isolating and Growing Bone Marrow–Derived Progenitor Cells Capable of Forming Bone Tissue

It has been demonstrated that bone marrow (BM)-derived pluripotent stem cells can be incorporated into muscle, bone, nerve, lung, stomach, intestine, and skin. Fibrin-based biodegradable microbeads (FMB) were developed for culturing, in suspension, a high density of cells, mostly of mesenchymal origin. In the current study, FMB were used to isolate and expand mesenchymal progenitor cells from BM of mice and rats. Cells from BM isolated on FMB (FMB-BM cells) were visualized by fluorescent confocal microscopy and quantified by a modified MTS colorimetric assay. Downloading the BM cells from FMB onto plastic induced their differentiation into islets of cells with osteogenic phenotype that secreted mineralized extracellular matrix. This was augmented by inducers of osteogenesis, such as ascorbic acid, beta-glycerophosphate, and dexamethasone, or osteoblast-growth peptides (OGP). Implanting FMB-BM cells under the kidney capsule in mouse tested the osteogenic potential of these cells in vivo. Thirty days after implantation, bone structures with typical BM elements were seen in 8/53 kidneys in 6-Gy-irradiated mice and in 1/10 kidneys in nonirradiated recipients; bone formation was verified by soft x-ray imaging and elemental analysis that showed elevated Ca and Fe in the implant region. FMB-BM cells - downloaded onto plastic flasks, cultured for 2 weeks, mechanically harvested and then implanted - induced 100% bone formation in both irradiated (6/6) and nonirradiated (3/3) mice. Histology revealed well-organized bone structures under the kidney capsule, including osteoblasts and typical elements of BM. Our findings demonstrate that FMB are capable of isolating and expanding progenitor cells from BM for osteogenesis and possibly for regenerating other mesenchymal tissues.

Moringa Oleifera aqueous leaf extract down-regulates nuclear factor-kappaB and increases cytotoxic effect of chemotherapy in pancreatic cancer cells

BackgroundFewer than 6% patients with adenocarcinoma of the pancreas live up to five years after diagnosis. Chemotherapy is currently the standard treatment, however, these tumors often develop drug resistance over time. Agents for increasing the cytotoxic effects of chemotherapy or reducing the cancer cells’ chemo-resistance to the drugs are required to improve treatment outcome. Nuclear factor kappa B (NF-kB), a pro-inflammatory transcription factor, reportedly plays a significant role in the resistance of pancreatic cancer cells to apoptosis-based chemotherapy. This study investigated the effect of aqueous Moringa Oleifera leaf extract on cultured human pancreatic cancer cells - Panc-1, p34, and COLO 357, and whether it can potentiates the effect of cisplatin chemotherapy on these cells.MethodsThe effect of Moringa Oleifera leaf extract alone and in combination with cisplatin on the survival of cultured human pancreatic cancer cells was evaluated by XTT-based colorimetric assay. The distribution of Panc-1 cells in the cell cycle following treatment with Moringa leaf extract was evaluated by flow cytometry, and evaluations of protein levels were via immunoblotting. Data of cell survival following combined treatments were analyzed with Calcusyn software.ResultsMoringa Oleifera leaf extract inhibited the growth of all pancreatic cell lines tested. This effect was significant in all cells following exposure to ≥0.75 mg/ml of the extract. Exposure of Panc-1 cells to Moringa leaf extract induced an elevation in the sub-G1 cell population of the cell-cycle, and reduced the expression of p65, p-IkBα and IkBα proteins in crude cell extracts. Lastly, Moringa Oleifera leaf extract synergistically enhanced the cytotoxic effect of cisplatin on Panc-1 cells.ConclusionMoringa Oleifera leaf extract inhibits the growth of pancreatic cancer cells, the cells NF-κB signaling pathway, and increases the efficacy of chemotherapy in human pancreatic cancer cells.

ErbB4 increases the proliferation potential of human lung cancer cells and its blockage can be used as a target for anti-cancer therapy.

Clinical and experimental data suggest that ErbB‐4, a member of the epidermal growth factor receptor family, may have a role in cancer progression and response to treatment. We found recently, using a retrospective clinical analysis, that expression of ErbB‐4 receptor is correlated with metastatic potential and patient survival in non‐small‐cell lung cancer (NSCLC). The purpose of this work was to correlate the expression of the ErbB‐4 and lung cancer cells growth in vitro and in vivo and to determine the therapeutic potential of a monoclonal antibody to ErbB‐4 against lung cancer. For this aim, we ectopically expressed ErbB‐4 in a human NSCLC cell line that did not express the ErbB‐4 protein. Overexpression of ErbB‐4 produced a constitutively activated ErbB‐4 receptor. The transfected ErbB‐4 positive clones showed an increased cell proliferation in vitro and in vivo in comparison with parental ErbB‐4 negative cells and with the cells transfected by neomycin‐resistant gene. A monoclonal antibody to ErbB‐4 showed both an inhibitory effect on growth rate and an increasing apoptotic rate in the cells expressing ErbB‐4. The results of the current study provide evidence that ErbB‐4 plays a significant role in human lung cancer and may serve as a molecular target for anticancer therapy.

Curcumin: A Potential Radio-Enhancer in Head and Neck Cancer

To investigate whether curcumin enhances the cytotoxic effect of radiotherapy in head and neck squamous cell carcinoma (HNSCC).

Combination of cisplatin and radiation in cell culture: Effect of duration of exposure to drug and timing of irradiation

Responses to the combination of cisplatin (CDDP) and radiation in experimental and clinical studies have been reported to vary from high radiosensitization to clear sub‐additivity. We examined the combined effect of CDDP with ionizing radiation in both murine mammary adenocarcinoma (EMT‐6) and human ovarian carcinoma (OV‐1063) cells with special reference to the duration of CDDP exposure and timing of irradiation. Cell survival was measured with a colorimetric assay of cell density. The nature of interaction of cisplatin and radiation was evaluated using isobolograms and a combination index (CI). Exposure of both cell lines to CDDP for 24 hr before irradiation yielded an additive or slightly sub‐additive response only if the exposure was extended for a few more hours after irradiation. In EMT‐6 cells, the combination of radiation with subsequent continuous as well as short‐term (4 to 6 hr) CDDP treatment was found to have a clear sub‐additive effect; dose escalation of each modality reduced the additional effect of the other. The sub‐additive effect may be explained by a radiation‐induced arrest of cells in late S phase, which was dose‐ and time‐dependent. Post‐radiation exposure to CDDP further increased the S‐phase arrest. In contrast, a 2 hr post‐radiation drug exposure resulted in a supra‐additive combined effect. Our results stress the crucial role of the timing and the doses of both modalities as well as the duration of post‐radiation drug exposure on their combined effect. Int. J. Cancer 75:635–642, 1998.

Late effects of dose fractionation on the mechanical properties of breast skin following post-lumpectomy radiotherapy

PURPOSE Late radiation-induced skin effects were studied in a multicenter project using our new sensitive noninvasive viscoelasticity skin analyzer (VESA). METHODS AND MATERIALS Skin viscoelasticity and anisotropy were examined quantitatively in symmetric areas of both breasts in healthy women and in 110 breast cancer patients who underwent lumpectomy and radiotherapy. These parameters were evaluated by the VESA measurement of the speed of elastic wave propagation in the skin; higher VESA readings correspond to higher skin stiffness. Effect of radiation was estimated by comparison of the data recorded in the irradiated versus nonirradiated breast of the same patient. RESULTS Skin viscoelasticity and anisotropy were similar in contralateral areas of the breasts in healthy controls as well as in the nonirradiated breasts of the patients. With age, skin viscoelasticity decreased and anisotropy increased similarly in both breasts. Radiotherapy, by a total radiation dose in the range of 45-50 Gy given with 1.8 Gy/fraction (fx) resulted in a similar minor, but still statistically significant, increase of skin stiffness relative to control. The effect was more pronounced when a dose of 50 Gy was given in a higher dose/fraction of 2.5 Gy. CONCLUSION We found that the increase in dose of radiation per fraction had much more impact on the development of late skin effects than elevation in the total dose given.

Plasma platinum elimination in a hemodialysis patient treated with cisplatin

The pharmacokinetics of intravenously administrated cisplatin (CDDP) were studied in a patient with meduloblastoma receiving regular hemodialysis for chronic renal failure. The patient received four CDDP infusions of 25 mg/m2 in two courses and underwent hemodialysis before each treatment and in intervals of 48 h thereafter with blood sampling at the beginning and the end of each hemodialysis. The data obtained were compared with the pharmacokinetic data from follow-up studies of 19 CDDP treatments in 15 patients suffering from various malignancies with no renal failure where a biexponential pharmacokinetic curve was recorded. The data of platinum (Pt) elimination of the patient receiving hemodialysis resembled the curve of those who had not, but following the second CDDP treatment in each course the peak Pt level in plasma was doubled, with a somewhat slower rate of elimination.

Paclitaxel-induced modification of the effects of radiation and alterations in the cell cycle in normal and tumor mammalian cells.

The cytotoxicity of paclitaxel (taxol) is associated mainly with block in G2/M phase, the most radiosensitive phase of the cell cycle. Nevertheless, taxol-induced modification of the effects of radiation may vary from clear sensitization to subadditivity. Therefore, this effect was studied in relation to drug-induced alterations in the distribution of cells in the phases of the cell cycle in tumor cells (EMT-6 and OV-1063) and normal skin fibroblasts. Cell survival was evaluated with two colorimetric assays. The cell cycle was evaluated by FACS analysis of doubly-labeled cells. The radiosensitivity of the different cells studied was similar, apart from the less radiosensitive human fibroblasts. However, their dose- and time-dependent sensitivity to taxol varied significantly. After 24 h exposure of EMT-6 cells to taxol (IC50 approximately 20 nM), the fraction of cells in G2/M phase increased, the fraction in S phase decreased, and the proportion of possibly apoptotic cells with subdiploid and subtetraploid DNA content increased; this coincided with radiosensitization. In OV-1063 cells (IC50 approximately 3 nM), the drug-induced G2/M-phase block was most pronounced, but the combined effect with radiation was merely additive. In human fibroblasts (IC50 approximately 35 nM), a minimal G2/M-phase block with no change in the S phase and a massive elevation of apoptotic cells with subdiploid DNA content was accompanied by a subadditive combined effect with radiation. Six hours of exposure to taxol increased the fraction of cells in S phase in both nonsynchronized and S-phase-synchronized human fibroblasts (G1 phase approximately 65%, S phase approximately 13%). This was accompanied by a pronounced subadditive effect of the combined treatment. However, in G1-phase synchronized human fibroblasts (G1 phase > or =90%, S phase approximately 3%), only the fraction of cells in G2/M phase was slightly elevated, with a merely additive response to the combined treatment. The differences in the response to the combined treatment between slowly and rapidly proliferating cells in relation to modifications in the cell cycle are discussed.

Targeting ErbB-1 and ErbB-4 in irradiated head and neck cancer: Results of in vitro and in vivo studies

ErbB oncogenes have a major role in cancer. The role of ErbB‐4 in cancer cell biology and the effect of anti‐ErbB‐1 and anti‐ErbB‐4 monoclonal antibodies were evaluated in this study.