[Oligometastatic non-small cell lung cancer--surgical options and therapy strategies]

Incomplete radiofrequency ablation accelerates proliferation and angiogenesis of residual lung carcinomas via HSP70/HIF-1α

Radiofrequency ablation (RFA) therapy has been proved effective and feasible for lung cancer. However, the molecular mechanisms of local lung cancer recurrence following RFA are poorly understood. The present study aimed to evaluate the ability of HSP70/HIF-1α to affect the proliferation and angiogenesis of non-small cell lung cancers (NSCLCs) following insufficient RFA to uncover the molecular mechanisms of local recurrence. In vitro heat treatment was used to establish sublines of NCI-H1650 cells. The NCI-H1650 subline that was established by heat treatment at 54°C had a relatively higher viability and significantly elevated heat tolerance (compared to the parental strain). After treatment with the HSP70 inhibitor VER-155008, the HIF-1α inhibitor YC-1 and PI3K/Akt inhibitor wortmannin, the viability and proliferation rate of the cells was measured. At the same time, HSP70, HIF-1α and Akt were detected by real-time PCR and western blotting. In vivo xenograft tumors were created by subcutaneously inoculating nude mice with NCI-H1650 cells. HSP70, HIF-1α and Akt were detected by western blotting, and CD34 expression was detected by immunohistochemistry before and after RFA or treatment with the VER-155008, YC-1 or wortmannin inhibitors. The heat-adapted NCI-H1650 subline established in vitro had a higher viability and proliferative activity compared to parental cells. Inhibiting HSP70/HIF-1α abolished this difference. Blocking the PI3K/Akt signaling pathway decreased HSP70/HIF-1α expression levels. In vivo, we found that incomplete RFA treatment promoted HSP70/HIF-1α and CD34 expression. Additionally, the combination of RFA and treatment targeting HSP70/HIF-1α resulted in a synergistic reduction in tumor growth compared to incomplete RFA alone. The PI3K/Akt signaling pathway is also involved in regulating HSP70/HIF-1α expression during this process. We conclude that the accelerated proliferation and angiogenesis potential of residual lung carcinomas following RFA treatment was induced by HSP70/HIF-1α, expression of which is regulated by the PI3K/Akt signaling pathway.

Local recurrence of small cell lung cancer following radiofrequency ablation is induced by HIF-1α expression in the transition zone

Local recurrence of lung cancer following radiofrequency ablation (RFA) treatment is common. The aims of the present study were to assess how RFA treatment affects the growth of small cell lung cancer (SCLC) micrometastases in the transition zone (TZ) surrounding the ablated region and in the reference zones (RZs) of the ablated or unablated lobes and to identify the molecular mechanism(s) of lung cancer recurrence following RFA treatment. After lung micrometastases of human SCLCs had formed, RFA treatment was applied to the right upper lobe (RUL) of the lung in nude mice. Hypoxia inducible factor (HIF)-1α expression, proliferation and angiogenesis potential both in the TZ and RZ were evaluated over time. Separately, at day 1, 7 and 14 following RFA treatment, the growth of micrometastases showed an ~2-fold increase in the TZ compared to the RZ of the unablated lobe, as the right lower lobe (RLL) and the growth of micrometastases in the RZ of the RUL was also induced by RFA. In addition, accelerated tumor growth in the TZ was induced by HIF-1α, but was not associated with tissue angiogenesis potential. We concluded that local recurrences of SCLCs caused by overproliferation of micrometastases following RFA treatment were driven by HIF-1α, although angiogenesis was not the driving force in the TZ.