Effect of thermal dose on heat shock protein expression after radio-frequency ablation with and without adjuvant nanoparticle chemotherapies

Abstract

Purpose To evaluate the effect of different radiofrequency ablation(RFA) thermal doses on coagulation and heat shock protein(HSP) response with and without adjuvant nanotherapies. Materials and Methods First, Fischer rats were assigned to nine different thermal doses of hepatic RFA(50°C–90°C, 2–20min; n=3/group) or no treatment(n=3). Next, 5 of these RF thermal doses were combined with liposomal-doxorubicin(Lipo-Dox, 1mg IV) in R3230 breast tumors, or no treatment tumors(n=5/group). Finally, RFA/Lipo-Dox was given without and with an HSP70 inhibitor, micellar quercetin(Mic-Qu, 0.3mg IV) for two different RFA doses with similar coagulation but differing periablational HSP70(RFA/Lipo-Dox at 70°Cx5min and 90°Cx2min;single tumors, n=5/group). All animals were sacrificed 24hr post-RFA and gross tissue coagulation and HSP70(maximum rim thickness and % cell positivity) were correlated to thermal dose including cumulative equivalent minutes at 43°C(CEM43°C). Results Incremental increases in thermal dose(CEM43°C) correlated to increasing liver tissue coagulation(R2=0.7), but not with periablational HSP70 expression(R2=0.14). Similarly, increasing thermal dose correlated to increasing R3230 tumor coagulation for RF alone and RFA/Lipo-Dox(R2=0.7 for both). The addition of Lipo-Dox better correlated to increasing HSP70 expression compared to RFA alone(RFA:R2=0.4, RFA/Lipo-Dox:R2=0.7). Finally, addition of Mic-Qu to two thermal doses combined with Lipo-Dox resulted in greater tumor coagulation(p<0.0003) for RFA at 90°Cx2min (i.e. greater baseline HSP70 expression) than an RFA dose that produced similar coagulation but less HSP expression(p<0.0004). Conclusion Adjuvant IV Lipo-Dox increases periablational HSP70 expression in a thermally dependent manner. Such expression can be exploited to produce greater tumor destruction when adding a second adjuvant nano-drug (Mic-Qu) to suppress periablational HSP expression.

Radiofrequency ablation (RFA)-induced systemic tumor growth can be reduced by suppression of resultant heat shock proteins

“…Initially, three standardized thermal ablation protocols were compared (‘lower power, longer duration’ RFA with power titrated to a tip temperature of 60°C applied for 10 min, ‘medium power, intermediate duration’ RFA with tip temperatures of 70°C for 5 min, and ‘higher power, shorter duration’ RFA at 90°C for 2 min, all in normal liver to simulate the standard clinical endpoint of ablating a margin of normal liver (21, 22). All three of these doses have previously been shown to result in similarly-sized ablation zones (6.1 ± 0.1 mm) in the models studied here (19). A control arm of sham treatment with probe placement without applicator activation/ablation was also introduced.…”

“…Prior studies have demonstrated that the tissue reactions occurring in the periablational rim, including both local reactions such as HSP70 and HIF-1α, and distant off-target tumorigenic effects mediated by HGF/c-Met and VEGF, vary based on thermal ablation heating technique (18, 19). Likewise, in this study, we noted that heat shock protein expression in the periablational rim also correlated with variable hepatic RF ablation, with greater expression occurring for lower power / longer heating ‘low-dose’ settings.…”

“…In a recent study using hepatic MW ablation, the use of high energy, shorter ablation times to create an identical-sized ablation zone obtained using a lower energy, longer ablation time protocol not only reduced local periablational inflammatory cell recruitment and heat shock protein 70 (HSP70) expression, but also reduced distant subcutaneous tumor growth as well (18). Additionally, although it has been previously demonstrated that the dose of RF ablation can substantially alter HSP expression surrounding similar sized ablation zones (19), whether such changes in dose can affect the extent of RF-induced tumorigenesis and any potential relationship to HSP production is currently unknown. Nevertheless, given the known association between heat shock proteins and cancer cell survival, including activation of some pathways implicated in ablation-induced tumor stimulation (such as HIF-1a and VEGF), we hypothesized that reducing periablational non-lethal hyperthermic effects via specific HSP inhibitors may offer an additional way to reduce off-target ablation-induced tumor stimulation (20).…”

Moderate hyperthermic heating encountered during thermal ablation increases tumor cell activity

“…In the first phase, to determine whether growth factors associated with tumorigenesis can be induced by tumor cells themselves, an in vitro assay was established to assess the effect of moderate hyperthermia doses found in the periablational zone on tumorigenesis factor induction, protein secretion, and activation post-thermal ablation. R3230 cells were heated to 43-45 C for 5-10 min as these thermal doses occur in the periablation region where there is induction of substantial cell stress and heat shock protein (HSP) production in this model [17][18][19][20][21]. Cells were incubated thereafter at 37 C for 1.5, 3, and 8 h (N ¼ 135).…”

Inactivation kinetics of food-borne pathogens subjected to thermal treatments: a review

“…Ohmic heating has been used to inactivate Escherichia coli O157:H7, Salmonella Typhimurium and Listeria monocytogenes in orange and tomato juice [19]. Populations of foodborne pathogens during heat treatment change with heating temperature, water activity (a w ), heating rate, pH, heat shock, recovery medium and composition/physical characteristics of the foods [20][21][22][23][24][25][26][27]. For example, when the ground beef inoculated with Escherichia coli O157:H7 was cooked in a water bath for 1 h at temperature of 55-62.5 C, the D-value (the time required at a certain temperature to reduce a specific microbial population by 90% or by a factor of 10) was significantly lower in ground beef adjusted with pH 4.5 than pH 5.5 [22].…”