Azidothymidine (AZT) as a Potential Modifier of Radiation Response in Vitro

The potential effect of AZT as a thymidine analogue on radiation response in vitro was investigated. Two human cell lines (WiDr and HeLa) were used. The effect of 10 μM AZT on exponentially growing cells was studied after different exposure times (24, 48 and 72 h). The surviving fraction (clonogenic assay) or metabolic activity (MTT assay) after irradiation of AZT-exposed cells, was compared to unexposed irradiated controls. Flow cytometry was used to assess the cell-cycle effect of pre-exposure of exponentially growing cells to AZT. AZT had a radioprotective effect for all experimental time points as far as WiDr was concerned. For HeLa the effect was significant at 24 h. Cell-cycle analysis showed a significant accumulation in S-phase at 72 h for WiDr. For HeLa there was a significant accumulation in S-phase at 48 h. We conclude that under the reported experimental conditions, AZT as a thymidine analogue seems to reduce the cytotoxic effect of irradiation.     

Early Interim PET Scans in Diffuse Large B-Cell Lymphoma: Can There Be Consensus About Standardized Reporting, and Can PET Scans Guide Therapy Choices?

The prognosis value of interim positron emission tomography (PET) remains controversial in diffuse large B-cell lymphoma (DLBCL) patients because of the absence of consensus on criteria able to early identify good and bad responders to treatment. Visual interpretation using the International Harmonization Project (IHP) criteria, primarily established for end of treatment evaluation, was related to a low positive predictive value of treatment failure. The 5-point scale (5PS) that refers the residual uptake to the liver as background tissue was shown to slightly reduce false-positive interim PET interpretations compared to IHP criteria. Semiquantification of fluorodeoxyglucose (FDG) uptake using standardized uptake value (SUV) and assessment of reduction of maximum SUV (SUVmax) between baseline and interim PET drastically improves both the interpretation accuracy and the interobserver reproducibility, and better predicts patient outcome than visual analysis. This latter approach is feasible in a multicenter setting and allows clinicians to design a risk-adapted therapeutic strategy based on early PET response assessment.     

Pure seminoma: A review and update

Background

Prostate cancer (PrCa) displays resistance to radiotherapy (RT) and requires radiotherapy dose escalation which is associated with greater toxicity. This highlights a need to develop radiation sensitizers to improve the efficacy of RT in PrCa. Ionizing radiation (IR) stimulates pathways of IR-resistance and survival mediated by the protein kinase Akt but it also activates the metabolic energy sensor and tumor suppressor AMP-Activated Protein Kinase (AMPK). Here, we examined the effects of the polyphenol resveratrol (RSV) on the IR-induced inhibition of cell survival, modulation of cell cycle and molecular responses in PrCa cells.

Methods

Androgen-insensitive (PC3), sensitive (22RV1) PrCa and PNT1A normal prostate epithelial cells were treated with RSV alone (2.5-10 μM) or in combination with IR (2-8 Gy). Clonogenic assays, cell cycle analysis, microscopy and immunoblotting were performed to assess survival, cell cycle progression and molecular responses.

Results

RSV (2.5-5 μM) inhibited clonogenic survival of PC3 and 22RV1 cells but not of normal prostate PNT1A cells. RSV specifically sensitized PrCa cells to IR, induced cell cycle arrest at G1-S phase and enhanced IR-induced nuclear aberrations and apoptosis. RSV enhanced IR-induced expression of DNA damage (γH2Ax) and apoptosis (cleaved-caspase 3) markers as well as of the cell cycle regulators p53, p21^cip1 and p27^kip1. RSV enhanced IR-activation of ATM and AMPK but inhibited basal and IR-induced phosphorylation of Akt.

Conclusions

Our results suggest that RSV arrests cell cycle, promotes apoptosis and sensitizes PrCa cells to IR likely through a desirable dual action to activate the ATM-AMPK-p53-p21^cip1/p27^kip1 and inhibit the Akt signalling pathways.     

Diagnostic value of serum IL-6 level in monoclonal gammopathies

Summary. The serum level of IL-6 was reported to reflect disease severity in patients with multiple myeloma. We used a specific radioimmunoassay to measure the level of IL-6 in 239 serum samples in which a monoclonal gammopathy was identified for the first time. The same sample was used for the measurement of serum C reactive protein and serum albumin. Then, an inventory of clinical and biological features allowed us to classify these patients into five groups: monoclonal gammopathy of undetermined significance (MGUS: 128), multiple myeloma (MM:66), Waldenström's macroglobulinaemia (WM:27), non-Hodgkin's lymphoma (NHL: 11) and chronic lymphocytic leukaemia (CLL: 7). The number of patients with serum IL-6 (S-IL-6) level >0.335 ng/ml (upper limit in normal sera) was significantly higher in the MM group (35%; Confidence Interval (CI) 23.5–46.5) compared with the MGUS group (15%; CI 8.8–21.2). The distribution of S-IL-6 levels was also significantly different between the groups (Mann-Whitney test: P< 0.01). High S-IL-6 levels were measured in 5/11 patients with NHL and 9/27 patients with WM. The distribution of S-IL-6 levels in these groups was the same as that in MGUS or MM groups. In patients with MM, elevated S-IL-6 levels were associated with haemoglobin level <100 g/l (P< 0.005). bone marrow plasmocytosis >50% (P<0.05) and stages II and III in the Durie & Salmon staging system (P< 0.005). The S-IL-6 level was also related to light chain component excretion in urine (P<0.01) and M component serum level for IgA (P<0.01). In patients with MGUS, the S-IL-6 level correlated with serum CRP level (P<0.05). serum lactate dehydrogenase (P< 0.05) and serum ferritin (P < 0.01). We conclude that the S-IL-6 level is a marker of high tumour burden in multiple myeloma. However, S-IL-6 level can be increased in patients with MGUS in relation to inflammatory parameters. Therefore the S-IL-6 level does not demonstrate high predictive value for the diagnosis of MM in patients with newly identified monoclonal gammopathy.