Effects of combined treatment of chemotherapeutics and hyperthermia on survival and the regulation of heat shock proteins in dunning R3327 prostate carcinoma cells

Abstract

BACKGROUND Hyperthermia can enhance the clinical response of chemotherapeutic agents in prostate cancer, but optimal sequencing of this combination therapy needs to be developed. Given the role of heat shock proteins (HSPs) in the development of resistance (thermotolerance) to subsequent hyperthermic stresses as well as to certain chemotherapeutics, the study of HSP regulation is important in the establishment of effective schedules in multimodal treatment strategies. METHODS In this study we evaluated the effects of the chemotherapeutic agents cisplatin, 5‐fluorouracil, and adriamycin in combination with hyperthermia. (43°C, 1 h) on clonogenic survival and inducible HSP70 regulation in Dunning rat adenocarcinoma of the prostate. HSP70 was analyzed by Western blot and by measuring β‐galactosidase produced by cells stably transfected with a gene construct containing the E. coli β‐galactosidase gene driven by the Drosophila HSP70 promoter. RESULTS Colony formation assays revealed a sensitizing effect of hyperthermia when simultaneously combined with each chemotherapeutic agent, resulting in a potentiated cytotoxicity compared to subsequenced treatments. Thermotolerant cells showed a significantly better survival when treated with adriamycin alone, but also when each chemotherapeutic agent was combined with hyperthermia. This enhanced survival was correlated with inducible HSP70 accumulation. The chemotherapeutics modified the HSP70 promoter activation induced by hyperthermia, suggesting changes in the development of cellular thermotolerance. CONCLUSIONS Our data reveal synergistic cytotoxic effects of the synchronous application of chemotherapeutic agents and hyperthermia on this model of prostate cancer. Furthermore, they demonstrate that the induction of HSPs in thermotolerant cells, as measured by HSP70 induction, results in a modulation the chemotherapeutic‐mediated cytotoxicity. Therefore, HSP70 is a useful marker of cellular resistance in multimodal approaches combining hyperthermia and chemotherapeutic agents in the treatment of locally advanced prostate carcinoma. Prostate 34:195–202, 1998. © 1998 Wiley‐Liss, Inc.

Hsp70B′ regulation and function

“…To obtain insight into the role of Hsp70BЈ in cellular physiology, we screened a series of Hsp inducers for their ability to activate hsp70BЈ. Cytotoxic agents examined in this study included GD, an Hsp90 inhibitor; Znϩϩ, a heavy metal ion; BA, a short chain fatty acid; and 5-FU, a pyrimidine analog (Roigas et al 1998;Winklhofer et al 2001;Qing et al 2004;Arvans et al 2005). 5-Aza, a DNA methyltransferase inhibitor shown to cause effects similar to heat shock under certain conditions, also was tested (Kim et al 1999;Gober et al 2003).…”

Effective cancer laser-therapy design through the integration of nanotechnology and computational treatment planning models

“…Higher levels of HSP can lead to increased tumor recurrence 11,12 . As a result, applied thermal stress associated with hyperthermia can induce the offsetting effects of HSP upregulation and cell necrosis 11,12,14 . The success of thermal therapies is characterized most often according to the equivalent thermal dose (the equivalent time that a tissue was at T = 43 o C, which is threshold for thermal injury) and the associated temperature dependent cellular injury 15 .…”

Heat shock protein expression and injury optimization for laser therapy design

“…The effectiveness of hyperthermic therapies, such as thermal ablation (i.e., high temperature T > 558C based tissue coagulative treatments), local hyperthermia (low temperature $42-448C), or hyperthermia sensitization as an adjuvant to radiotherapy, chemotherapy, brachytherapy, and thermally mediated drug or gene deliveries, can be compromised due to heat shock proteins (HSP) induction in regions of the tumor where non-lethal temperature elevation occurs [1][2][3]. Molecular chaperons such as HSP assist in refolding and repair of denatured proteins and aid in synthesis of new proteins in response to injury in both normal and cancerous cells [4][5][6].…”

“…Applied thermal stress can induce the offsetting effects of over-expressed HSP and hyperthermia-mediated cell necrosis. Although HSP perform critical functions in the normal cell, upregulation of HSP in tumor cells following thermal stress can lead to poor treatment outcomes by enhancing tumor cell viability and imparting cellular resistance to chemotherapy and radiation treatments which are generally employed in conjunction with hyperthermia [1][2][3]. HSP have been implicated in many roles of therapeutic resistance including multi-drug resistance [7], regulation of apoptosis [8], and modulation of p53 functions [9] for a broad range of neoplastic tissues due to upregulated expression in cancer cells and through induction by thermal stress.…”