Differential temperature sensitivity of normal and cancer cells in culture

Poly(ethylene-imine)-Functionalized Magnetite Nanoparticles Derivatized with Folic Acid: Heating and Targeting Properties

Magnetite nanoparticles (MNPs) coated by branched poly (ethylene-imine) (PEI) were synthesized in a one-pot. Three molecular weights of PEI were tested, namely, 1.8 kDa (sample MNP-1), 10 kDa (sample MNP-2), and 25 kDa (sample MNP-3). The MNP-1 particles were further functionalized with folic acid (FA) (sample MNP-4). The four types of particles were found to behave magnetically as superparamagnetic, with MNP-1 showing the highest magnetization saturation. The particles were evaluated as possible hyperthermia agents by subjecting them to magnetic fields of 12 kA/m strength and frequencies ranging between 115 and 175 kHz. MNP-1 released the maximum heating power, reaching 330 W/g at the highest frequency, in the high side of reported values for spherical MNPs. In vitro cell viability assays of MNP-1 and MNP-4 against three cell lines expressing different levels of FA receptors (FR), namely, HEK (low expression), and HeLa (high expression), and HepG2 (high expression), demonstrated that they are not cytotoxic. When the cells were incubated in the presence of a 175 kHz magnetic field, a significant reduction in cell viability and clone formation was obtained for the high expressing FR cells incubated with MNP-4, suggesting that MNP-4 particles are good candidates for magnetic field hyperthermia and active targeting.

Versatile quarto stimuli nanostructure based on Trojan Horse approach for cancer therapy: Synthesis, characterization, in vitro and in vivo studies

Nanostructured delivery and diagnostic systems that induces specific targeting properties by exploiting the local physicochemical tumour characteristics will be evaluated is the present work. It is well known that cancer cells have specific physicochemical characteristics, which can be taken into consideration for the design of a broad spectrum of drug delivery systems (DDS). Some of those characteristics including the different temperature environment their susceptibility when temperature ranges between 40 and 43°C where cell apoptosis is induced, the intra- and extra-cellular pH which varies from 6.0 to 6.8, for cancer cells, and 6.5 to 7.4 for normal cells respectively, (lysosomes acidic pH ranges 4-5). Additional significant factors are the overexpressed receptors on the tumour surface. Loading and release studies were carried out by using the anthracycline drug Doxorubicin and their cytotoxicity was evaluated by using the MTT assay in healthy and diseased cell lines. The highlight of this work is the in vitro and in vivo studies which were performed in order to evaluate different nanostructures as for their biodistribution, pharmacokinetic and toxicity per se.

Layer-by-Layer Assemblies for Cancer Treatment and Diagnosis

The layer-by-layer (LbL) technique was introduced in the early 1990s. Since then, it has undergone a series of technological developments, making it possible to engineer various theranostic platforms, such as films and capsules, with precise control at the nanometer and micrometer scales. Recent progress in the applications of LbL assemblies in the field of cancer therapy, diagnosis, and fundamental biological study are highlighted here. The potential of LbL-based systems as drug carriers is discussed, especially with regard to the engineering of innovative stimuli-responsive systems, and their advantageous multifunctionality in the development of new therapeutic tools. Then, the diagnostic functions of LbL assemblies are illustrated for detection and capture of rare cancer cells. Finally, LbL-mimicking extracellular environments demonstrate the emerging potential for the study of cancer cell behavior in vitro. The advantages of LbL systems, important challenges that need to be overcome, and future perspectives in clinical practice are then highlighted.

Nanoparticles for inhibition of in vitro tumour angiogenesis: synergistic actions of ligand function and laser irradiation

Careful design of nanoparticles plays a crucial role in their biomedical applications. It not only defines the stability of nanoparticles in a biological medium but also programs their biological functionality and specific interactions with cells. Here, an inorganic nanoparticulate system engineered to have a dual role as anti-angiogenic and hyperthermic agent is presented. The inorganic rod-shaped core is designed to strongly absorb near-infrared laser irradiation through the surface plasmon resonance and convert it into localized heat, while a peptide coating acts as an anti-angiogenic drug, altogether inhibiting vascular growth. The synergistic dual action provides an improved inhibition of the in vitro tumour angiogenesis, offering new possibilities for the development of nano-engineered anti-angiogenic drugs for therapies.

Chip-based size-selective sorting of biological cells using high frequency acoustic excitation

This work presents the size-selective sorting of single biological cells using the assembly process known as templated assembly by selective removal (TASR). We have demonstrated experimentally, for the first time, the selective placement and sorting of single SF9 cells (clonal isolate derived from Spodoptera frugiperda (Fall Armyworm) IPLB-Sf21-AE cells) into patterned hemispherical sites on rigid assembly templates using TASR. Nearly 100% of the assembly sites on the template were filled with matching cells (with assembly density as high as 900 sites per mm(2)) within short time spans of 3 minutes. 3-D reconstruction of cell profiles and volume analysis of cells trapped inside assembly sites demonstrates that only those cells that match the assembly site precisely (within 0.5 μm) in size are assembled on the template. The assembly conditions are also compatible with the extension of TASR to mammalian cells. TASR-based size-selective structuring and sorting of biological systems represents a valuable tool with potential for implementation in biological applications such as cell sorting for medical research or diagnostics, templating for artificial tissue replication, or isolation of single cells for the study of biological or mechanical behavior.

Long lasting heat shock stimulation of TRAIL-induced apoptosis in transformed T lymphocytes

We report that a mild heat shock, that did not impair cell growth, stimulated TNF-related apoptosis inducing ligand (TRAIL)-mediated apoptosis of leukemic T lymphocytes and promyelocytic cells, but not normal human T lymphocytes. The death stimulation was maximal when the heat shock was performed at the beginning of the exposure to TRAIL. However, enhanced apoptosis was still observed when TRAIL was added one day after heat shock. The phenomenon was transcription and translation independent suggesting that newly made heat shock proteins were not involved. TRAIL-induced apoptosis after heat shock was dependent on caspases and FADD and an enhanced FlipL/S processing was noticed. However, since after the heat shock FlipL/S processing was transient, events upstream of caspase 8 and FADD may be responsible of the long lasting enhanced TRAIL apoptosis observed after heat shock. No heat-mediated alteration in the antibody recognition of cell surface DR4 and DR5 TRAIL receptors was observed. However, in the presence of TRAIL, a long lasting attenuation in the antibody detection of DR4 and DR5 was observed in heat shock-treated cells that correlated with the enhanced apoptogenic efficiency of TRAIL.

Rationale for hyperthermia with intraoperative intraperitoneal chemotherapy agents

Hyperthermia is selectively cytotoxic for malignant cells due to inhibition of oxidative metabolism causing lower pH in the microenvironment of the malignant cells and tumor. The increased acidity increases lysosymal activity and subsequent cell death. Hyperthermia alone as a primary treatment modality for malignancy has largely been abandoned due to high morbidity and mortality and high recurrence rates. Advances in administration and monitoring of hyperthermia, especially for regional applications, has allowed for the use of hyperthemia in conjunction with other modalities of antineoplastic therapy. Hyperthermia has been shown to potentiate chemotherapy and radiation by several different mechanisms. HIIC uses the advantages of hyperthermia in conjunction with chemotherapy for the management of peritoneal carcinomatosis. Several different chemotherapy agents have been shown to have improved therapeutic index and efficacy when used with hyperthermia in the management of peritoneal carcinomatosis.

Perfusion induced hyperthermia for oncologic therapy with cardiac and cerebral protection

Cancer can be preferentially damaged and killed at temperatures above 41.0 degrees C. However, the heart and brain malfunction at this temperature, limiting the application of systemic hyperthermia in the treatment of metastatic cancer. We created a hyperthermic perfusion system that maximizes the temperature differential produced and extends the safe hyperthermic time. Mongrel dogs were anesthetized and mechanically ventilated. Temperature probes were placed in the rectum, bladder, peritoneal cavity, proximal aorta, pulmonary artery, and right tympanic canal. Venoarterial perfusion was instituted and the perfusate was warmed to 44 to 45 degrees C. The dogs' rectal temperature was elevated to > or = 42 degrees C for 4 hours. A small amount of venous blood was cooled to 28 to 30 degrees C and reperfused into the right atrium to maintain the pulmonary artery temperature < or = 38 degrees C. At the end of the perfusion, the dogs were decannulated, recovered, and returned to their cages for observation. Ten of 11 dogs survived the operative procedure, and no neurologic deficits were observed. The rectal temperature was successfully elevated to > or = 42 degrees C for 4 hours while maintaining the heart and brain at < or = 38 degrees C. Moderate serum biochemical changes were observed postprocedure. However, only the aspartate transaminase and alkaline phosphatase levels remained elevated above both the baseline and canine reference values by day 7. Lower abdominal and pelvic hyperthermia at 42 degrees C can be safely produced and maintained for 4 hours using an extracorporeal perfusion circuit, while protecting the heart and brain from temperature elevation.

Sensitivity to Nd:YAG induced laserthermia is a cell-type-specific feature not directly related to tumorigenic potential or proliferation rate

BACKGROUND AND OBJECTIVE

Laser-induced hyperthermia, laserthermia, is a promising new method for treating neoplasms. The response of different cell types to conventional hyperthermia varies [Bhuyan, Cancer Res 1979; 39:2277-2284; Raaphorst et al., Cancer Res 1979; 39:396-401]. We investigated the possible relationship between sensitivity to laser treatment and tumorigenic potential of three closely related cell types. Non-tumorigenic cells PYS-2 and differentiated F9S1 were compared to tumorigenic cells F9S1.

STUDY DESIGN/MATERIALS AND METHODS

The contact Nd:YAG laser was used in a continuous-wave mode with a power setting of 6W, exposure times were 2 and 4 min [Castrén-Persons et al., Lasers Surg Med 1991; 11:595-600; Castrén-Persons, unpublished data]. The frosted-end probe was placed in the middle of the well and a thermocouple was attached 5 mm from the tip of the probe. The total amount of energy was measured for each well. A 4 min, 44 degrees C water bath treatment was used as comparison. Untreated wells served as controls. May-Grünwald-Giemsa staining and 3H-thymidine labeling were used for the analysis.

RESULTS

Laserthermia killed all three cell types significantly more effectively than the water bath. PYS-2 cells were the most sensitive to the laser treatment. At the same temperature, PYS-2 cells were only slightly affected by water bath induced heating; the differentiated F9 cells were the most sensitive to this treatment. During the laser treatments, the energy required for holding the temperature seemed to depend not only on the cell type but also on the amount of cells treated: the more cells in the well, the more energy was needed.

CONCLUSION

Our results suggest that laser sensitivity is a cell-type specific feature which is not directly related to the proliferation rate or benign or malignant behavior of the cells.

Thermal sensitivity in NIH 3T3 fibroblasts transformed by the v-fos oncogene. Correlation with reduced accumulation of 68-kDa and 25-kDa stress proteins after heat shock

The effect of v-fos transformation on the cellular response to heat shock has been investigated. NIH 3T3 fibroblasts were transfected with the FBR p75gag-fos gene fusion under the control of the long terminal repeat (LTR) promoter of Finkel-Biskin-Reilly (FBR) murine sarcoma virus and with the gene encoding hygromycin resistance. Several hygromycin-resistant clone isolates, that expressed various levels of p75gag-fos oncoprotein, were analyzed as they displayed properties of transformed cells, such as altered morphology, shorter doubling time, serum-independent growth and foci formation in soft agar. The thermal response of these clones was compared to that of the control cells expressing the hygromycin-resistance gene only. Here, we report that the v-fos-transformed clones displayed an enhanced thermosensitivity which resulted in a reduced tolerance to thermal stress. Heat-treated v-fos-transformed cells displayed a decreased expression and accumulation of the major stress proteins Hsp68 (68-kDa heat-shock protein) and Hsp25 which probably resulted of a reduced accumulation of the corresponding mRNAs. This effect was particularly intense at the level of Hsp25. These alterations in cell survival and stress-protein expression appeared correlated to the level of p75gag-fos. At least for Hsp68, the transcription of this gene was not found altered by v-fos expression suggesting that this oncogene increases the turn-over of Hsp68 mRNA. After the heat-shock treatment, v-fos transformation also reduced the time period during which the constitutively expressed stress protein Hsc70 redistributes inside the nucleus. Since Hsp68 and Hsp25 are molecular chaperones that in vivo protect cells against the deleterious effects of heat shock, it is conceivable that their reduced accumulation and altered cellular distribution following heat shock may contribute, at least in part, to the thermosensitivity of v-fos-transformed NIH 3T3 fibroblasts.

Lethal effects of the combination of hyperthermia and bromocriptine or a somatostatin analogue on normal pituitary cells and pituitary tumour cells

Effects of hyperthermia alone and combined with bromocriptine (BC) or a somatostatin analogue (SMS 201-995) were studied in vitro on normal pituitary and pituitary tumour cells (GH3 cells). GH3 cells were more sensitive to heat than normal pituitary cells and a maximal difference in survival was obtained with hyperthermia at 42.5 degrees C for 6 h. BC had cytotoxic and antiproliferative effects on GH3 cells, whereas SMS 201-995 was not effective. Hyperthermia at 42.5 degrees C for 3 h in combination with BC enhanced selective cytotoxicity for GH3 cells. In contrast, combined treatment with hyperthermia and SMS 201-995 failed to enhance cytotoxicity for GH3 cells. The combination of hyperthermia and BC could provide improved therapeutic efficacy in patients with pituitary adenomas.

Cytocidal effects of bromocriptine, somatostatin analog, and heat on growth hormone-secreting pituitary adenoma in vitro

The effects of bromocriptine (BC), a somatostatin analog (SMS), and heat on the secretion of growth hormone (GH) and prolactin (PRL), and on the morphologic features of human GH-secreting pituitary adenoma were studied in vitro. The treatment with BC, SMS, or heat (41.5 degrees C and 42.5 degrees C) markedly suppressed the secretion of GH and PRL from the adenoma cells and reduced the number of cells immunoreactive with GH or PRL. The combined treatment with BC and heat induced a marked reduction in the number of GH and PRL cells consistent with the effect on the secretion of GH and PRL. These results suggest that BC, SMS, and heat treatments produced the cytotoxic effects on pituitary adenoma cells, and that the simultaneous treatment of BC and heat enhanced this effect.

Synergistic effects of irradiation and hyperthermia on established cell lines derived from maxillary carcinoma. Report II

We studied in vitro the capability of radiation, hyperthermia, and their combination to inhibit growth of cell strains isolated from maxillary carcinoma and their radiation tolerant strains. Synergic effects of the combination were studied by investigating effects of hyperthermia and radiation on cell cycles with BrdU pulse labelling to establish optimal conditions for the combination. Growth of cell strains from maxillary carcinoma was remarkably inhibited by thermal treatment because of retarded cellular cycles. Cells at the S-phase were so sensitive to heat that their intake of BrdU was debilitated. Radiation increased the proportion of cells at the S-phase that poorly synthesized DNA. When combining radiation with hyperthermia, the heat killed cells at the S-phase, which was prolonged by radiation, and survivors showed retarded cellular cycles; that is, synergism was found.

Increase in carcinoembryonic antigen release from cancer cells by combined treatment with retinoic acid and low-temperature hyperthermia

The growth of a human gastric adenocarcinoma cell line, MKN-45, was inhibited and the amount of carcinoembryonic antigen (CEA) in both the culture medium and the cell extract was increased in the presence of retinoic acid at a concentration of 75 (1.5x)-125 microM (1.9x), which did not substantially affect cell survival. Treatment using a combination of retinoic acid (125 microM) and low-temperature hyperthermia (40 degrees C, 30 min) was more effective in increasing CEA compared with retinoic acid alone (extracellular 1.9-2.4x, intracellular 1.5-1.9x). The inhibition of cell growth was reversed after the retinoic acid was removed from the medium. Cells treated with both retinoic acid and (low-temperature) hyperthermia, however, could be induced to release a significant amount of CEA at about 48 h after retinoic acid removal. The induced CEA increase in the cells, but not in the medium, was suppressed by actinomycin D (1 ng/ml) or cyclohexamide (0.2 microgram/ml). These results suggest that retinoic acid, used alone or in combination with hyperthermia, enhances the production and release of CEA in human gastric cancer cells.

Heat-induced damage to HeLa-S3 cells: correlation of viability, permeability, osmosensitivity, phase-contrast light-, scanning electron- and transmission electron-microscopical findings

The responses of HeLa S-3 to mild hyperthermia for relatively critical times at 43 and 45 degrees C were analysed in detail, including growth and colony-forming ability, permeability, osmotic sensitivity and microscopical appearances. For comparative purposes lower temperatures (e.g. 41 degrees C) and higher temperatures (50 and 55 degrees C) were used in some experiments. The evidence from many different aspects, including scanning and transmission electron microscopy, suggests that critical heat exposures do not per se cause severe membrane damage and loss of cell integrity, but changes quickly become manifest when cells are 'recovered' by returning to 37 degrees C. Attention is drawn to the ability of heat-treated cells to show osmotic-like swelling and restoration towards normal volume in medium of 30 per cent normal strength, which would not be expected on the hypothesis that hyperthermia primarily disrupts membrane structure and functioning. Ultrastructural changes during and after hyperthermia--including nucleolar changes, the appearance of perichromatin granules, the formation of electron-dense cytoplasmic clusters, and the development of intranuclear actin rods--corroborate and extend other findings. However, mitochondrial changes were found to be particularly significant, appearing early and correlating well with the loss of viability and metabolic functioning found after heat treatment. These include the early development of intramitochondrial dense granules, followed by vesicularization of the cristae, swelling of the intracristal spaces, myelin degeneration and the formation of bodies which could otherwise be mistaken for secondary lysosomes. The findings indicate the need for more intensive investigations of mitochondria and mitochondrial functioning in hyperthermia-induced cell damage, and their careful correlation with the 'recovery' of energy-dependent process in cells subsequently returned to 37 degrees C.

Effect of hyperthermia on electron transport in Ehrlich ascites tumor mitochondria

The effect of hyperthermia (1 hr, 41 degrees C) on the functional properties of Ehrlich ascites tumor mitochondria was investigated. Mitochondria isolated from Ehrlich ascites tumor after exposure of whole cells to 41 degrees C for 1 hr still phosphorylate and maintain a normal acceptor control ratio (ACR). The temperature decreases state 4 and ADP-and FCCP-stimulated respiration on various substrates entering at three energy-conserving sites of the respiratory chain. The inhibition of oxygen consumption by NAD- and FAD-linked substrates was 40% for state 4 and 70% for ADP- or FCCP-stimulated respiration. State 4 and FCCP-stimulated respiration of mitochondria on TMPD + ascorbate was affected 38% and 45%, respectively. ATPase activity was unaffected by hyperthermia, indicating that under these experimental conditions, the inhibition of ADP-stimulated respiration does not depend on an effect on either Fo F1-ATPase or adenine translocase, the activity of which is required for ATP entry prior to ATPase activity. Because of the inability to detect a specific site of action of temperature, it is conceivable that hyperthermia might inhibit substrate oxidation by altering some components of the inner mitochondrial membrane, which regulates the kinetic properties of the membrane-associated enzymes.

Normal cells and malignant cells transfected with the HRas oncogene have the same heat sensitivity in culture

Mouse embryo cells (C3H 10T1/2) were transfected with a plasmid (pAL8A) containing the HRas oncogene and neomycin resistance gene. Five transfected cell clones were isolated and established as cell lines, and these showed neomycin resistance. Two of these cell lines expressed a normal morphology while three showed a transformed morphology. Four of the cell lines produced tumours in nude mice. Flow cytometry measurements showed that exponentially growing cell cultures of the five transfected cell lines had the same cell cycle distribution as the normal parental cell line. The sensitivity to hyperthermia of the five transfected cell lines was the same as that of the normal cell line for temperatures ranging from 42.0 to 45.0 degrees C. Thus in these studies we found no difference in the thermal sensitivity of normal and malignant cells transfected by the Hras oncogene.

Hyperthermia for cancer: a practical perspective

A causal relationship between hyperpyrexia and tumor regression was first suggested in 1866, when Busch reported the cure of a histologically diagnosed sarcoma in a middle-aged woman, following a bout of erysipelas. Over the years, interest in the effect of heat on cancer has remained alive, but this interest has increased dramatically in recent years. The literature on this subject is broadly reviewed and the clinical results discussed. It is apparent from clinical studies thus far that it is a relatively simple undertaking to treat superficial neoplasms with hyperthermia. However, the major challenges in clinical thermotherapy pertain to patients with deeply situated tumors. The lack of safe and reliable methods of monitoring temperature in deep tissues is a major impediment to a thorough understanding of thermal dosimetry in clinical hyperthermia, and routine thermal dosimetry in clinical hyperthermia will have to await the development of reliable noninvasive thermometry. As responses have been reported with modest levels of hyperthermia, the need for thermometry is somewhat lessened, given that invasive monitoring is imperfect and somewhat risky when used in deeply seated tumours. The eventual place of thermotherapy in the treatment of malignant tumours in man is as yet unclear and must be rigourously and thoroughly assessed in well-designed, prospective, randomized patient trials.

Microwave-induced hyperthermia and ionizing radiation. Preliminary clinical results

The combination of microwave-induced (2450 MHz) hyperthermia and ionizing radiation was used in 7 patients with superficial malignant tumours, which were considered refractory to other therapy. A newly developed heating system was used, allowing for a maintained temperature at the master probe of 42.5 degrees C +/- 0.5 degrees C during 45 min, but temperature measurements at multiple sites showed a marked variation. This preliminary series indicates that the combination of hyperthermia and ionizing radiation may be useful, the response rate (complete or partial) being 8 of 8 evaluable lesions. Even previously heavily irradiated sites responded. Technical improvements are highly needed to allow for controlled heating of any tissue volume.

Iron and neoplasia

Normal and neoplastic cells (like nonpathogenic and pathogenic microorganisms) apparently have similar needs and tolerances for iron, but neoplastic cells (like pathogenic microorganisms) may exhibit altered mechanisms of iron acquisition that permit continued growth in host iron-restricted tissues. Excess iron tends to interfere with host defense against malignant cells (as well as against microbial invaders); severe iron deficiency may likewise be detrimental. Elevated temperature is more toxic towards neoplastic than to normal host cells; it is not yet known whether the site of action of heat might be associated with iron acquisition (as has been demonstrated for gram negative bacteria). Persons or animals with iron overload tend to be at greater risk than normal hosts in the development of neoplasms.Construction of animal models of iron overload, although difficult, is strongly indicated at this time. Based on such models, decisions then can be made about the extent to which (a) nutritional immunity against neoplastic cells is practiced by vertebrate hosts and (b) clinical procedures could be employed to strengthen such immunity as an adjunct to radiotherapy, chemotherapy, and surgery.

5-Thio-D-glucose selectively potentiates hyperthermic killing of hypoxic tumor cells

To investigate the mechanisms by which heat affects cancer cells, we used 5-thio-D-glucose, an inhibitor of glycolysis in HeLa S-3 cells, under aerobic and hypoxic conditions at temperatures ranging from 37 degrees to 43 degrees C. Drug alone or heat alone killed a minimum number of cells under aerobic or hypoxic conditions. Exposure to drug and hyperthermia selectively increased the number of cells killed under hypoxic conditions at temperatures as low as 40.5 degrees C but had little effect on cells incubated under aerobic conditions. These results suggest that the glycolytic pathways is a primary site of hyperthermic damage leading to cell death.

Effect of hyperthermia on malignant cells in vivo. A review and a hypothesis

The relevant literature is reviewed in an attempt to clarify the mechanism of heat-dependent tumor cell destruction in vivo. Malignant cells in vivo appear to be selectively destroyed by hyperthermia in the range of 41-43 degrees C. Heat evidently affects nuclear function, expressed by an inhibited RNA, DNA and protein synthesis and characteristic arrest or delay of cells in certain locations of the cell cycle. However, as these effects appear to be reversible and are observed in normal cells as well as malignant cells, they probably do not explain the hyperthermic induced selective in vivo destruction of malignant cells. Heat-induced cytoplasmic damage appears to be of more importance. Increased lysosomal activation is observed, and is further intensified by a relatively increased anaerobic glycolysis which develops selectively in tumor cells. A hypothesis is proposed and discussed which explains the marked and selective in vivo tumor cell destruction as a consequence of the enhancing effect on the cytoplasmic damage of certain environmental factors (e.g. increased acidity, hypoxia and insufficient nutrition.

Mutation selection and tumour progression

It is proposed that tumour progression results from the increased mutability of tumour cells and that this mutability leads to the acquisition of a large number of 'neutral' mutations having no significant effects under physiological conditions but capable of lethal expression under different conditions. High temperatures often lead to expression of neutral mutations and this could provide a mechanism for the observed thermosensitivity of tumour cells, and a rational basis for the use of hyperthermia in cancer treatment.