In recent years, cancer therapy research has focused on molecular targets. For efficient hyperthermic cancer therapy, potential targets of interest are molecules which respond to heat and selectively activate signal transduction factors which can inhibit cancer cell proliferation. Signal transduction pathways affected by heat include p53 mediated pathways, JNK (Jun N-terminal kinase) mediated pathways, Akt (protein kinase B) mediated pathways, NBS1 (Nijimegen breakage syndrome 1) mediated pathways, classic MAP (mitogen activated protein) kinase mediated pathways, and p38 MAP kinase mediated pathways. Events such as cell death, cell survival, cell proliferation, and/or cell cycle arrest can be affected by these pathways. To learn more about heat-induced gene and protein expression, cDNA arrays and protein microarrays were used to study cellular responses to heat. This paper briefly reviews interactions of pro- and anti-apoptotic genes and proteins which are induced by heat shock and are components of signal transduction pathways.

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It has been suggested that inducible heat shock proteins (HSPs) may function in multiple roles in cytoprotection. However, recent reports have shown that nitric oxide (NO) radicals are an initiator of heat- and radio-resistance, and act through the activation of the human homolog of MDM2 (HDM2), the depression of p53 accumulation, and the induction of NO synthase (iNOS, or alternatively, NOS2) which is observed following a priming irradiation. The aim of this work was to acquire additional information on the roles of p53, HDM2, iNOS, NO radicals, and HSPs on the development of heat- and radio-resistance as following a priming heat treatment. Wild-type (wt) p53 and mutated (m) p53 cells were used. These cells were derived from the H1299 human lung cancer cell line in which p53 is deleted. Cellular sensitivities were determined with a colony-forming assay. In both pre-heated wtp53 cells and in pre-heated mp53 cells, the induction of heat- and radio-resistance was observed in the absence of KNK437 (an inhibitor of HSPs), and in the presence of RITA (an inhibitor of p53-HDM2 interactions), aminoguanidine (an iNOS inhibitor) or c-PTIO (an NO radical scavenger). These findings suggest that following a priming heat treatment, HSPs contribute to heat- and radio-resistance.

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The counting and analysis of γH2AX foci is a widely used technique because these foci are considered to be a reliable indicator for the presence of DNA double-strand breaks (DSBs). The most frequently used method to count foci is to examine images and count by eye, but such an approach may not be the most accurate method to use. An alternative method to manual counting is proposed here, and this method is faster, easier, more objective, and can eliminate artifacts which can result from human handling. A dual-step algorithm is described which uses computational methods and consists of two distinct processes : (i) a 5-filter image filtering and processing step, and (ii) a foci counting/analyzing step. The benefits of this 2 stage computational analysis are primarily in the fact that the filtering process compensates for common preparation errors, as well as for image blurring and foci overlap. This method increases the sharpness of the foci edges and converts a 3D focus distance to an optical density, which can then be measured by the counting software. This allows researchers to compare the results of foci counts with increased reliability and objectivity. The features of this method also permit batch microscope images to be processed automatically. This system has a wide potential range of applications, including foci analysis from different types of immunofluorescence staining, and could form the basis for a standardized computational counting method which could eliminate counting subjectivity and provide an increase in counting reliability.

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