Hyperthermia induces therapeutic effectiveness and potentiates adjuvant therapy with non-targeted and targeted drugs in an in vitro model of human malignant melanoma

Abstract

In the present study, we have aimed to characterize the intrinsic, extrinsic and ER-mediated apoptotic induction by hyperthermia in an in vitro model of human malignant melanoma and furthermore, to evaluate its therapeutic effectiveness in an adjuvant therapeutic setting characterized by combinational treatments with non-targeted (Dacarbazine & Temozolomide) and targeted (Dabrafenib & Vemurafenib) drugs. Overall, our data showed that both low (43 °C) and high (45 °C) hyperthermic exposures were capable of inducing cell death by activating all apoptotic pathways but in a rather distinct manner. More specifically, low hyperthermia induced extrinsic and intrinsic apoptotic pathways both of which activated caspase 6 only as opposed to high hyperthermia which was mediated by the combined effects of caspases 3, 7 and 6. Furthermore, significant involvement of the ER was evident (under both hyperthermic conditions) suggesting its role in regulating apoptosis via activation of CHOP. Our data revealed that while low hyperthermia activated IRE-1 and ATF6 only, high hyperthermia induced activation of PERK as well suggesting that ultimately these ER stress sensors can lead to the induction of CHOP via different pathways of transmitted signals. Finally, combinational treatment protocols revealed an effect of hyperthermia in potentiating the therapeutic effectiveness of non-targeted as well as targeted drugs utilized in the clinical setting. Overall, our findings support evidence into hyperthermia’s therapeutic potential in treating human malignant melanoma by elucidating the underlying mechanisms of its complex apoptotic induction.

Hyperthermia Suppresses Post - In Vitro Proliferation and Tumor Growth in Murine Malignant Melanoma and Colon Carcinoma

“…In the present study, we utilized two in vivo murine models of malignant melanoma and colon carcinoma in order to examine hyperthermia's therapeutic effectiveness. Firstly, we aimed to validate our previous in vitro findings showing hyperthermia's capacity to activate apoptotic cell death in human malignant melanoma (A375) cells (39). For this reason, an in vivo murine model of malignant melanoma was utilized by injecting B16-F10 cells into the subcutaneous tissue of the back of the neck of C57BL/6 female mice.…”

“…According to their findings, the induction of cell death pathways is dependent on i) cancer cell type, ii) temperature and iii) duration of heat exposure (40,41). Previously we demonstrated that hyperthermia induces various apoptotic cascades and enhances the therapeutic effectiveness of non-targeted and targeted drugs in an in vitro model of human malignant melanoma (39). To this end, the aim of this study was to validate our previous in vitro findings in two in vivo models of murine malignant melanoma and colon carcinoma in an attempt to demonstrate hyperthermia's effectiveness as a cancer treatment option.…”

“…Overall, hyperthermia it has been shown to exert a wide range of effects including i) direct cytotoxicity in tumor cells, ii) modifications in the tumor microenvironment, iii) induction of heat shock proteins, iv), alterations in the immune response, v) stimulation of necrotic and apoptotic cascades, vi) changes in cell cycle-related signaling pathways, vii) changes in blood flow, oxygen and nutrient delivery to the site of tumor and finally, viii) enhancement of therapeutic outcome when applied in combination with other regimens (36)(37)(38). To this end, a recent study from our group has demonstrated the application of hyperthermia in an in vitro model of human malignant melanoma resulting in apoptotic activation while enhancing the efficacy of both targeted and non-targeted therapeutic drugs (39). Hence, in this study, we have aimed to utilize post-in vitro murine models of malignant melanoma and colon carcinoma in order to validate hyperthermia's effectiveness as a monotherapy protocol.…”

Hyperthermia Targeting the Tumor Microenvironment Facilitates Immune Checkpoint Inhibitors

“…While temperature rises between the “fever range” and “thermal ablation range” at 41–43°C, tumor cells died predominantly by apoptosis with a balance between pro-apoptosis and anti-apoptosis. This process involves the induction of CHOP, the alterations in calcium levels and the activation of ER proteases, calpain–calpastatin proteolytic system and caspase mediated apoptosis ( 30 , 31 ). This process also accompanies with the upregulation of eIF2 α phosphorylation.…”

In vitro effect of hyperthermic Ag and Au Fe3O4 nanoparticles in cancer cells

“…Regarding non-ionized 4T1, they show maximum 20% toxicity in the three concentrations tested, opposed to ionized 4T1 that in the concentrations 400 and 600 μg/ml of Fe3O4 show high toxicity (~58% and 65% respectively), indicating ionizationdependent toxicity. Fe3O4 core Αg shell NPs because of the toxic effect of Ag NPs on their own, compared to Au NPs that are considered to be the less toxic metal NPs for in vivo applications, do not seem to act as heating mediators [7,14]. Fe3O4 core Αg shell NPs show no ionization-dependent toxicity in both cell lines.…”