Development of cross-resistance between heat and cisplatin or hydroxyurea treatments in FaDu squamous carcinoma cells

Recombinant heat shock protein 70 in combination with radiotherapy as a source of tumor antigens to improve dendritic cell immunotherapy

Local radiotherapy (RT) plus intratumoral dendritic cell (DC) injection can mediate immunological response. We hypothesized that co-injection of exogenous recombinant heat shock protein 70 (rHsp70) in combination with RT-DC could be as effective as co-injection of HSP-peptide for evoking specific immune response. rHsp70-prostate-specific antigen (rHSP70C′-PSA) and α-fetoprotein (rHSP70C′-AFP) were used to compare specific response. Growth inhibition of the tumor and the systemic anti-tumor immune response were measured on CT26/PSA and CT26/AFP mice model. Intratumoral co-injection of rHsp70 and DC into the irradiated tumor site induced a more potent anti-tumor immune response than injection of DC alone. rHsp70 was as effective as rHsp70C′-PSA or rHsp70C′-AFP in inducing a tumor-specific cytotoxic T lymphocyte response or tumor growth delay. These results demonstrate that co-administration with rHsp70 and RT could be a simple and effective source of tumor antigens to achieve RT-DC immunotherapy protocol and easy to apply in clinical use.

Quercetin enhances susceptibility to NK cell-mediated lysis of tumor cells through induction of NKG2D ligands and suppression of HSP70

It is known that treatments with heat shock, some anticancer drugs, and ionizing radiation increase the expression of heat-shock proteins (HSPs) and natural killer group 2D (NKG2D) ligands in tumor cells. The increased HSPs may make the tumor cells resistant to apoptosis and reduction of HSPs may make the tumor cells more susceptible to natural killer (NK)-cell mediated lysis of tumor cells. In this study, we investigated whether quercetin which has inhibitory activities against heat-shock factor, protein kinase C, nuclear factor-kappaB, and phosphatidyl inositol 3-kinase, can modulate the expression of NKG2D ligands and suppress the HSPs in tumor cells. The results of this study showed that quercetin significantly induced the expression of several NKG2D ligands including major histocompatibility complex class I-related chain B, UL16-binding protein 1, and UL16-binding protein 2 in K562, SNU1, and SNU-C4 cells. The quercetin-treated K562, SNU1, and SNU-C4 cells showed an enhanced susceptibility to NK-92 cells through induction of NKG2D ligands. This increased expression of NKG2D ligands seemed to be due to the inhibition of the nuclear factor-kappaB and phosphatidyl inositol 3-kinase pathways. The findings of this study suggest that the induced NKG2D ligands with the decrease of HSP70 protein by quercetin may provide an attractive strategy to improve the effectiveness of NK cell-based cancer immunotherapy.

Bone morphogenetic protein-4 inhibits heat-induced apoptosis by modulating MAPK pathways in human colon cancer HCT116 cells

Cancer thermotherapy and radiofrequency ablation (RFA) have been adopted as modalities for treating various kinds of cancer. We have previously demonstrated that bone morphogenetic protein-4 (BMP-4) is up-regulated in colonic adenocarcinoma. Here, we investigated whether an increase of BMP-4 expression changes cellular response to heat treatment in human colon cancer HCT116 cells. BMP-4 overexpressing HCT116 cells generated by stable transfection showed a significantly increased survival rate and a decreased apoptotic rate in comparison to empty vector controls after heat treatment at 45 degrees C for 20min. The expression levels and pattern of HSP90, HSP70, and HSP27 after heat treatment were similar between these two cell lines. There was no difference in expression levels of Bcl-2 and Bax in these two cell lines and their expression remained unchanged after heat treatment. Both activities of the extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) were stimulated by heat in these cells. Comparatively, BMP-4 overexpressing cells had an intense and prolonged ERK activation, while a less intense and short JNK activation. Correspondingly, treatment of BMP-4 overexpressing cells with noggin, a BMP-4 antagonist, resulted in a reduction of heat-activated ERK but an increase of heat-activated JNK and significantly increased heat-induced apoptotic rate. These results indicate that BMP-4 can protect colon cancer cells from heat-induced apoptosis through enhancing the activation of ERK as well as inhibiting the activation of JNK.

Mechanisms of resistance to cisplatin and carboplatin

While cisplatin and carboplatin are active versus most common cancers, epithelial malignancies are incurable when metastatic. Even if an initial response occurs, acquired resistance due to mutations and epigenetic events limits efficacy. Resistance may be due to excess of a resistance factor, to saturation of factors required for tumor cell killing, or to mutation or alteration of a factor required for tumor cell killing. Platinum resistance could arise from decreased tumor blood flow, extracellular conditions, reduced platinum uptake, increased efflux, intracellular detoxification by glutathione, etc., decreased binding (e.g., due to high intracellular pH), DNA repair, decreased mismatch repair, defective apoptosis, antiapoptotic factors, effects of several signaling pathways, or presence of quiescent non-cycling cells. In lung cancer, flattening of dose-response curves at higher doses suggests that efficacy is limited by exhaustion of something required for cell killing, and several clinical observations suggest epigenetic events may play a major role in resistance.

Local Application of Hyperthermia in the Esophagus with a Heatable Malleable Thermoplastic Stent

OBJECTIVE

This study measures the effect of hyperthermia applied through a heatable stent in the esophagus in order to investigate whether this procedure offers a therapeutic option for tumor treatment.

MATERIAL AND METHODS

Thermoplastic malleable stents, with the capacity to be heated after implantation, were placed endoscopically in the middle third of the esophagi of 30 pigs. After placement the stents were heated in vivo for 60 min at temperatures ranging from 43 to 52 degrees C. Temperature was measured in the surrounding tissue at various distances from the stent, determining heat penetration. The esophagi were histologically examined after 7 days.

RESULTS

The maximal heating temperature tolerated in the esophagi without transmural necrosis was 46.5 degrees C, when applied twice for 60 min with a pause of 48 h. With this procedure a tumor damaging temperature of 42.5 degrees C was achieved at a maximum distance of 12 mm surrounding the stent.

CONCLUSION

Application of hyperthermia through a heatable stent in the esophagus is feasible. The maximal depth of therapeutic temperature achieved by this procedure (12 mm) is not sufficient to heal esophageal cancer, but may be of palliative value.

Heat shock protein 70 is induced in mouse human colon tumor xenografts after sublethal radiofrequency ablation

BACKGROUND

Radiofrequency ablation (RFA) destroys tumor cells by generating high temperatures through ionic vibration. Tumor recurrence may be a direct function of sublethal temperature. Further, a set of proteins called heat shock proteins (HSPs) can be synthesized under heat stress to facilitate recovery of tumor cells from heat damage.

METHODS

Subcutaneous xenografts were induced in nude mice by injection with HT29 human colon cancer cells. The tumors were exposed surgically and subjected to RFA. The tumors were randomly assigned to achieve a target tumor temperature of 42 degrees C, 45 degrees C, or 50 degrees C. Total RNA and cell lysates were isolated from tumor tissues and subjected to reverse transcription-polymerase chain reaction and Western blot analyses, respectively, at various time points after treatments for assessing HSP expression. For in vitro experiments, HT29 cells were subjected to variable temperatures, and HSP expression was assayed.

RESULTS

During a 50-day follow-up, the recurrence rates were 0% at 50 degrees C, 30% at 45 degrees C, and 100% at 42 degrees C. The messenger RNA and protein levels of HSP90 and HSP27 remained unchanged after RFA at 45 degrees C; however, HSP70 was induced at 4 and 10 hours after RFA. In vitro HT29 culture cells subjected to a heated water bath exhibited a cellular sensitivity to heat and change of HSP expression similar to those in tumor xenografts subjected to RFA.

CONCLUSIONS

Our data establish the requisite heat parameters during RFA for human colon tumors in vitro and in vivo. Because HSP70 plays an important role in protecting cell death from a variety of stresses, HSP70 could be a potential target for enhancing the efficacy of RFA.