BackgroundConformal intensity-modulated radiation therapy (IMRT) involves irradiation of large volume of normal tissue with low and medium doses, biological relevance of which is not clear yet. Serum proteome features were used here to study the dose-volume effects in patients irradiated with IMRT due to head and neck cancer.MethodsBlood samples were collected before and during RT, and also about one month and one year after the end of RT in a group of 72 patients who received definitive treatment. Serum proteome profiles were analyzed using MALDI-ToF mass spectrometry in 800–14,000 Da range.ResultsMajor changes in serum proteome profiles were observed between pre-treatment samples and samples collected one month after RT. Radiation-related changes in serum proteome features were affected by low-to-medium doses delivered to a large fraction of body mass. Proteome changes were associated with intensity of acute radiation toxicity, indicating collectively that RT-related features of serum proteome reflected general response of patient’s organism to irradiation. However, short-term dose-related changes in serum proteome features were not associated significantly with the long-term efficacy of the treatment.ConclusionsThe effects of low and medium doses of radiation have been documented at the level of serum proteome, which is a reflection of the patient’s whole body response.

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NF-jB transcription factor regulates numerous genes important for inflammation, immune responses and cell survival. HSF1 is the primary transcription factor activated under stress conditions that is responsible for induction of genes encoding heat shock proteins. Previous studies have shown that the NF-jB activation pathway is blocked by heat shock possibly involving heat shock proteins. Here, we investigate whether active HSF1 inhibited this pathway in the absence of stress conditions. Activation of the NF-jB pathway and expression of NF-jBdependent genes were analyzed in TNFa-stimulated U-2 OS human osteosarcoma cells that were either heat-shocked or engineered to express a constitutively active form of HSF1 in the absence of heat shock. As expected, heat shock resulted in a general blockade in the degradation of the IjBa inhibitor, nuclear translocation of NF-jB and expression of NF-jB-dependent target genes. In marked contrast, the presence of constitutively active HSF1 did not block TNFa-induced activation of the NF-jB pathway or expression of a set of the NF-jB-dependent genes. We conclude that in the absence of heat shock, the NF-jB activation pathway is inhibited by neither active HSF1 transcription factor nor by increased levels of HSF1-induced heat shock proteins.

DFF40/CAD endonuclease is primarily responsible for internucleosomal DNA cleavage during the terminal stages of apoptosis. The nuclease specifically introduces DNA double strand breaks into chromatin substrates. Here we performed a detailed study on the specificity of the nuclease using synthetic single-stranded and double-stranded ribo- and deoxyribo-oligonucleotides as substrates. We have found that neither single-stranded DNA, single-stranded RNA, double-stranded RNA nor RNA-DNA heteroduplexes are cleaved by the DFF40/CAD nuclease. Noteworthy, all types of oligonucleotides that are not cleaved by the nuclease inhibit cleavage of double-stranded DNA. We have also observed that in cells undergoing apoptosis in vivo neither the activation of DFF40/CAD nor oligonucleosomal chromatin fragmentation was temporally correlated with either total cellular or nuclear RNA degradation. We conclude that DFF40/CAD is exclusively specific for double-stranded DNA.