Chronic thermotolerance with continued cell proliferation

Modulation of Local Cellular Activities using a Photothermal Dye-Based Subcellular-Sized Heat Spot

Thermal engineering at the microscale, such as the regulation and precise evaluation of the temperature within cellular environments, is a major challenge for basic biological research and biomaterials development. We engineered a polymeric nanoparticle having a fluorescent temperature sensory dye and a photothermal dye embedded in the polymer matrix, named nanoheater-thermometer (nanoHT). When nanoHT is illuminated with a near-infrared laser at 808 nm, a subcellular-sized heat spot is generated in a live cell. Fluorescence thermometry allows the temperature increment to be read out concurrently at individual heat spots. Within a few seconds of an increase in temperature by approximately 11.4 °C from the base temperature (37 °C), we observed the death of HeLa cells. The cell death was observed to be triggered from the exact local heat spot at the subcellular level under the fluorescence microscope. Furthermore, we demonstrate the application of nanoHT for the induction of muscle contraction in C2C12 myotubes by heat release. We successfully showed heat-induced contraction to occur in a limited area of a single myotube based on the alteration of protein-protein interactions related to the contraction event. These results demonstrate that even a single heat spot provided by a photothermal material can be extremely effective in altering cellular functions.

Forcing the Antitumor Effects of HSPs Using a Modulated Electric Field

The role of Heat Shock Proteins (HSPs) is a “double-edged sword” with regards to tumors. The location and interactions of HSPs determine their pro- or antitumor activity. The present review includes an overview of the relevant functions of HSPs, which could improve their antitumor activity. Promoting the antitumor processes could assist in the local and systemic management of cancer. We explore the possibility of achieving this by manipulating the electromagnetic interactions within the tumor microenvironment. An appropriate electric field may select and affect the cancer cells using the electric heterogeneity of the tumor tissue. This review describes the method proposed to effect such changes: amplitude-modulated radiofrequency (amRF) applied with a 13.56 MHz carrier frequency. We summarize the preclinical investigations of the amRF on the HSPs in malignant cells. The preclinical studies show the promotion of the expression of HSP70 on the plasma membrane, participating in the immunogenic cell death (ICD) pathway. The sequence of guided molecular changes triggers innate and adaptive immune reactions. The amRF promotes the secretion of HSP70 also in the extracellular matrix. The extracellular HSP70 accompanied by free HMGB1 and membrane-expressed calreticulin (CRT) form damage-associated molecular patterns encouraging the dendritic cells’ maturing for antigen presentation. The process promotes killer T-cells. Clinical results demonstrate the potential of this immune process to trigger a systemic effect. We conclude that the properly applied amRF promotes antitumor HSP activity, and in situ, it could support the tumor-specific immune effects produced locally but acting systemically for disseminated cells and metastatic lesions.

Preclinical evaluation of the novel monoclonal antibody H6-11 for prostate cancer imaging

The biological properties of the novel monoclonal antibody (mAb) H6-11 and its potential utility for oncological imaging studies were evaluated using in vitro and in vivo assays. Immunoreactivity of H6-11 to the human prostate cancer PC-3 cell line and solid tumor xenografts was initially demonstrated using immunofluorescence staining; the specificity of H6-11 for prostate cancer was further evaluated using a commercial array of human prostate cancer and normal tissue samples (n=49) in which H6-11 detected 95% of prostate adenocarcinomas. The Kd value of 61.7±30 nM was determined using 125I-labeled H6-11. Glycosylation analysis suggested the antigenic epitope of the glycan is an O-linked β-N-acetylglucoside (O-GlcNAc) group. Imaging studies of PC-3 tumor-bearing mice were performed using both optical imaging with NIR fluorescent dye-labeled H6-11 and microPET imaging with 89Zr-labeled H6-11. These in vivo studies revealed that the labeled probes accumulated in PC-3 tumors 48-72 h postinjection, although significant retention in liver was also observed. By 120 h postinjection, the tumors were still evident, although the liver showed significant clearance. These studies suggest that the mAb H6-11 may be a useful tool to detect prostate cancer in vitro and in vivo.

Glycan array analysis of the antigen repertoire targeted by tumor-binding antibodies

Immunization with whole cells has been used extensively to generate monoclonal antibodies, produce protective immune responses, and discover new disease antigens. While glycans are abundant on cell surfaces, anti-glycan immune responses have not been well-characterized. We used glycan microarrays to profile 49 tumor-binding monoclonal antibodies generated by immunizing mice with whole cancer cells. A substantial proportion (41%) of the tumor binding antibodies bound carbohydrate antigens. The antibodies primarily recognize a group of 5 glycan antigens: Sialyl Lewis A (SLeA), Lewis A (LeA), Lewis X (LeX), blood group A (BG-A), and blood group H on a type 2 chain (BG-H2). The results have important implications for monoclonal antibody production and cancer vaccine development.

HSP27 phosphorylation increases after 45°C or 41°C heat shocks but not after non-thermal TDMA or GSM exposures

PURPOSE

Experiments with cultured HeLa, S3 and E.A. Hy296 cells were performed to determine if exposure to acute (30 min at 45 degrees C) or chronic (2 h at 41 degrees C) heat shocks or to non-thermal exposures of radiofrequency radiation (RF) induce changes in HSP27 phosphorylation.

MATERIALS AND METHODS

The radiofrequency (RF) exposures used in this study were 847 MHz time division multiple access modulated (TDMA) at a specific absorption rate (SAR) of 5 W kg-1 for 1, 2 or 24 h or 900 MHz GSM modulated (GSM) at a SAR of 3.7 W kg-1 for 1, 2 or 5 h. HSP27 phosphorylation was evaluated by resolving the various phosphorylation forms using two-dimensional gel electrophoresis measuring the relative amount of each by densitometry. Alternatively, an antibody specific for phosphorylated HSP27 was used to detect changes in HSP27 phosphorylation levels. All heat shock and RF exposure conditions were analysed simultaneously along with a matched incubator control sample. Each experiment was repeated three times.

RESULTS

Following heat shock, the degree of phosphorylation of HSP27 varied with the heat dose, with acute hyperthermia (45 degrees C) having an increased proportion of higher phosphorylated forms. Exposure of HeLa S3 cells to 5 W kg-1 TDMA for 1, 2 or 24 h did not induce significant differences in the levels of HSP27 phosphorylation compared to incubator control or sham. Exposure of E.A. Hy926 cells to 3.7 W kg-1 900 MHz GSM for 1, 2 or 5 h did not induce significant differences in the levels of HSP27 phosphorylation compared to sham exposed.

CONCLUSIONS

Acute and moderate hyperthermia significantly increase HSP27 phosphorylation, but there was no significant change in the levels of HSP27 following non-thermal exposure to TDMA and GSM modulated RF radiations.

The effects of 41°C hyperthermia on the DNA repair protein, MRE11, correlate with radiosensitization in four human tumor cell lines

PURPOSE

The goal of this study was to determine if reduced availability of the DNA repair protein, MRE11, for the repair of damaged DNA is a basis for thermal radiosensitization induced by moderate hyperthermia. To test this hypothesis, we measured the total amount of MRE11 DNA repair protein and its heat-induced alterations in four human tumor cell lines requiring different heating times at 41 degrees C to induce measurable radiosensitization.

MATERIALS AND METHODS

Human colon adenocarcinoma cell lines (NSY42129, HT29 and HCT15) and HeLa cells were used as the test system. Cells were irradiated immediately after completion of hyperthermia. MRE11 levels in whole cell extract, nuclear extract and cytoplasmic extracts were measured by Western blotting. The nuclear and cytoplasmic extracts were separated by TX100 solubility. The subcellular localization of MRE11 was determined by immunofluorescence staining.

RESULTS

The results show that for the human tumor cell lines studied, the larger the endogenous amount of MRE11 protein per cell, the longer the heating time at 41 degrees C required for inducing measurable radiosensitization in that cell line. Further, the residual nuclear MRE11 protein level, measured in the nuclear extract and in the cytoplasmic extract as a function of heating time, both correlated with the thermal enhancement ratio (TER).

CONCLUSIONS

These observations are consistent with the possibility that delocalization of MRE11 from the nucleus is a critical step in the radiosensitization by moderate hyperthermia.

Monoclonal antibody CC188 binds a carbohydrate epitope expressed on the surface of both colorectal cancer stem cells and their differentiated progeny

PURPOSE

Recently, cancer stem cells (CSC), undifferentiated cancer progenitor cells, have been successfully isolated from colorectal tumors. Targeting both CSCs and differentiated, rapidly proliferating tumor cells with therapeutic drugs provides a focused strategy to treat cancer. In this study, we isolated the monoclonal antibody (mAb) CC188 and characterized the epitope recognized by mAb CC188, which is useful for developing biological reagents that target CSCs.

EXPERIMENTAL DESIGN

We used a hybridoma technique to generate mAbs and an immunomagnetic method to isolate colon CSCs. We characterized mAb CC188 binding epitope and examined the epitope distribution in normal and tumor tissues, particularly in CSCs using tissue arrays and immunofluorescence staining method. We also evaluated the effect of mAb CC188 on invasiveness of NSY tumor cells.

RESULTS

mAb CC188 was generated and 98.9% (187 of 189 cases) of colon cancer were positively stained by mAb CC188. "+", "++," and "+++" staining were 25.9%, 28.6%, and 43.4%, respectively. The mAb CC188 binding epitope was identified as a carbohydrate, which was expressed on the surface of colon CSCs (CD133+), differentiated colon cancer cells (CD133-), and cells from various types of epithelial tumors. In contrast, the expression of the carbohydrate epitope was low in normal prostate muscle and pancreatic acinar cells, as well as in some normal epithelial cells of the breast duct, cervix, and skin. A functional study indicated that mAb CC188 suppressed the invasiveness of NSY tumor cells.

CONCLUSION

mAb CC188 selectively targets a carbohydrate epitope expressed on cancer cells, providing a viable method for specific tumor imaging and targeted therapy.

Increased thermosensitivity of mouse colorectal carcinoma cells transfected with human FUT1 gene

The thermal responses of mouse colorectal carcinoma cells were investigated in the wild type cells and the transfected cells with human FUT1 gene which encodes alpha 1,2fucosyltransferase. The heat sensitivity was observed to increase in the FUT1 gene transfected cells and the effect of hyperthermia at 44 degrees C on these cells was demonstrated to be significant (P<0.001) to the wild type cells even though no remarkable difference in the expression of the heat shock protein, Hsp70 was found in these cells. Thus the expression of alpha 1,2fucosylated antigens seemed to increase the heat sensitivity in mouse colorectal carcinoma cells.

Mild heat shock induces proliferation, alkaline phosphatase activity, and mineralization in human bone marrow stromal cells and Mg-63 cells in vitro

Bone formation has been shown to be stimulated by local diathermy in vivo; however, the mechanisms involved in this heat-induced osteogenesis are unclear. In this study, we investigated the direct effect of temperature on human bone marrow-derived stromal cells (BMSCs) and the human osteoblast-like, osteosarcoma-derived MG-63 cells in culture conditions. Both cell types were shown to tolerate the transient exposure to mild heat shock conditions (1 h at 39-41 degrees C), and long-term (96 h) exposure at 39 degrees C stimulated DNA synthesis in BMSC but caused growth arrest in MG-63 cells. Furthermore, 1-h exposure to higher temperatures (42.5-45 degrees C) or continuous 96-h exposure to 40 degrees C or 41 degrees C inhibited the proliferation of both BMSCs and MG63 cells. The level of alkaline phosphatase (ALP) in these cells linearly correlated with the increase in temperature, and the ALP expression, either at the basal level or in response to 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], was enhanced after a single 1-h exposure to 42.5 degrees C. In addition, continuous incubation at 39 degrees C or repeated transient exposure to 39/41 degrees C greatly enhanced the ability of BMSCs to form mineralizing nodules. The heat shock protein HSP70, which was expressed constitutively by BMSCs, was found to be up-regulated by hyperthermia (39 degrees C) and down-regulated at 33 degrees C. The expression of HSP70 could be induced in MG-63 cells by both low- and high-temperature conditions. These data suggest that treatment with a mild heat shock induces the proliferation and differentiation of osteoprogenitor cells, and the direct effects of temperature on bone-forming cells might be one of the mechanisms involved in heat-induced bone formation in vivo.

Thermal radiosensitization of human tumour cell lines with different sensitivities to 41.1 degrees C

While much work on radiosensitization by hyperthermia in the 43 degrees C and higher temperature range has been done, relatively little work has been done at temperatures in the 41-42 degrees C range. In this moderate hyperthermia range there are dramatic differences in the resistance of mammalian cells to hyperthermia. Therefore, thermal radiosensitization was measured in two human colon adenocarcinoma cell lines, one that expresses chronic thermotolerance and proliferates at 41.1 degrees C, NSY 42129 (NSY) cells and one that is slowly killed at 41.1 degrees C, HCT15 cells. Heat-resistant NSY cells were found to be more radioresistant than heat-sensitive HCT15 cells. Hyperthermia at 41.1 degrees C enhanced the radiation sensitivity in NSY cells, but no significant induction of heat-induced radiosensitization was observed in HCT15 cells. The radiation sensitivity induced by 41.1 degrees C in NSY cells appeared to be related to both intrinsic heat-induced radiosensitization (HIR) and cell-cycle redistribution at 41.1 degrees C. Incidentally, cells incubated at 41.1 degrees C for between 8-16 h displayed an identical radiosensitivity to those heated for 24 h. This result implies that modest hyperthermia for 2 h or more can have a radiosensitizing effect in heat-resistant cells.

Intracellular distribution of hsp70 during long duration moderate hyperthermia

Hyperthermia causes cell killing and is also an effective radiosensitizer. In recent years, the protocol of long duration moderate hyperthermia (LDMH) has been used to treat cancer patients in the clinic. However, the results of many studies indicate that some tumour cells may reveal the capability to express chronic thermotolerance, a factor of potentially critical impact in the efficacy of clinical hyperthermia. Previously it has been reported that two out of five human cell lines studied were able to proliferate at 41.1 degrees C. In the present study, the intracellular distribution of hsp70 during LDMH was measured as a potential marker for chronic thermotolerance with continued cell proliferation. In all cell lines studied, hsp70 became localized in the nucleus immediately after the cells were shifted from 37 degrees C to 41.1 degrees C. However, in the two cell lines which recovered and continued to proliferate, NSY42129 and HT29, hsp70 was delocalized from the nucleus within 4 h. Conversely, in the cell lines for which 41.1 degrees C was lethal, hsp70 did not delocalize from the nucleus but rather became localized in the nucleolar regions. Neither the NSY42129 cells nor the HT29 cells showed any preferential nucleolar punctate staining. Thus, it appears that the pattern of hsp70 nuclear localization and delocalization is related to the cells' ability to survive moderate heat shocks.