Heat-induced growth inhibition and apoptosis in transplanted human head and neck squamous cell carcinomas with different status of p53

Therapeutic strategies for head and neck cancer based on p53 status

Squamous cell carcinomas of the head and neck (HNSCC) are one of the most common types of cancers worldwide, and despite advances in treatment, they still represent a clinical challenge. Inactivation of one or more components in the p53 signaling pathway is an extremely common event in human neoplasia, including HNSCC. The loss of p53 function is responsible for increased aggressiveness in cancers, while tumor chemoresistance and radioresistance can depend on deleted p53 expression, or on the expression of mutated-p53 proteins. Thus, consideration and manipulation of the p53 status during HNSCC cancer therapy should be considered. This review discusses the p53 signaling pathways activated by various cellular stresses, including exposure to cancer therapies. The recognition of the p53 status in cancer cells is a significant factor and could provide valuable assistance during the selection of an effective therapeutic approach.

Analysis of thermochemotherapy-induced apoptosis and the protein expressions of Bcl-2 and Bax in maxillofacial squamous cell carcinomas

The aim of this study is to investigate the relationship between thermochemotherapy-induced apoptosis and the expressions of the Bcl-2 and Bax proteins in maxillofacial squamous cell carcinomas. Fifteen patients with maxillofacial squamous cell carcinomas were treated with microwave hyperthermia (43 °C for 40 min) following the intravenous injection of pingyangmycin (Bleomycin A5 Hydrochloride for Injection) (8 mg). Subsequently, the tumors were surgically resected. The terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick-end labeling method was used to assess the apoptosis in the carcinoma cells, and immunohistochemistry was performed using the streptavidin-peroxidase method to determine the expression levels of the Bcl-2 and Bax proteins, and quantitative analysis was employed. The number of apoptotic cells increased markedly (P < 0.001). The protein expression of Bcl-2 was downregulated (P < 0.001), while that of Bax was markedly upregulated (P < 0.001). Thermochemotherapy induces apoptosis in maxillofacial squamous cell carcinoma cells by downregulating the protein expression of Bcl-2 and upregulating that of Bax.

Hyperthermia inhibits cell proliferation and induces apoptosis: relative signaling status of P53, S100A4, and Notch in heat sensitive and resistant cell lines

The effects of hyperthermia on the expression of p53, the apoptosis-associated genes Bax and Bcl-2, Notch and S100A4 have been studied in the HepG2 cell line and the HUT cell line derived from HepG2, adapted for growth in hyperthermic conditions. Hyperthermia inhibits cell proliferation and induces apoptosis. HepG2 and HUT cells differed in respect of anchorage to growth surface, degree of proliferation and apoptosis and expression of p53, Bax, Bcl-2, Notch, and S100A4 genes. The induction of apoptosis and the inhibition of cell proliferation occurred independently of p53, and independently also of involvement of the apoptosis family genes Bax and Bcl-2. We demonstrate novel and marked differences between transient heat shock and heat adaptation in respect of pathways of signaling and generation of phenotypic effects in vitro. Different signaling patterns have been identified here. Pathways of signaling by S100A4, by its interaction with and sequestration of p53, and by Notch also seem differentially operational in the induction of apoptosis, and both appear to be activated as alternative pathways in the context of hyperthermia signaling independently of p53.

Change in expression of apoptosis genes after hyperthermia, chemotherapy and radiotherapy in human colon cancer transplanted into nude mice

AIM: To investigate the change in expression of p53, Bcl-2, and Bax genes in human colon cancer cells transplanted into nude mice after hyperthermia, chemotherapy, radiotherapy, thermochemotherapy, thermoradiotherapy and thermochemoradiotherapy.

METHODS: Human colon cancer cell line (HT29) was transplanted into the hind limbs of nude mice. Under laboratory simulated conditions of hyperthermia (43°C, 60 min), the actual radiation doses and doses of mitomycin C (MMC) were calculated in reference to the clinical radiotherapy for human rectal cancer and chemotherapy prescription for colon cancer. The mice were divided into 6 groups according to the treatment approaches: hyperthermia, chemotherapy, radiotherapy, thermochemotherapy, thermoradiotherapy, and thermochemoradiotherapy. The mice were sacrificed at different time points and the tumor tissue was taken for further procedures. The morphologic changes in membrane, cytoplasm and nuclei of tumor cells of p53, Bcl-2, and Bax after treatment, were observed by immunohistochemistry staining.

RESULTS: All of the six treatment modalities down-regulated the expression of p53, Bcl-2 and up-regulated the expression of Bax at different levels. The combined therapy of hyperthermia, with chemotherapy, and/or irradiation showed a greater effect on down-regulating the expression of p53 (0.208 ± 0.009 vs 0.155 ± 0.0115, P < 0.01) and Bcl-2 (0.086 ± 0.010 vs 0.026 ± 0.0170, P < 0.01) and up-regulating Bax expression (0.091 ± 0.0013 vs 0.207 ± 0.027, P < 0.01) compared with any single therapy.

CONCLUSION: Hyperthermia enhances the effect of radio- and chemotherapy on tumors by changing the expression of apoptosis genes, such as p53, Bcl-2 and Bax.

Cellular and molecular mechanism and application of hyperthermia for tumor therapy

Hyperthermia is effective in the treatment of neoplasm, but its mechanism remains unclear for a long time. In recent years, great advances were achieved on its mechanism. In vitro and in vivo studies show that heat-induced apoptosis plays a dominant role in mild and moderate hyperthermia while necrosis in serious one. Heat induces apoptosis through mitochondria or/and death receptor pathways, and oxidative stress, intracellular Ca²⁺ increase and some molecules such as p53 and Bax play important roles in this process. Based on this mechanism, new therapies have been investigated and developed, including hyperthermia combined with gene therapy, calcium- and oxidative stress-targeted therapy, or decreasing extracellular pH value, which may remarkably enhance the effect of hyperthermia.