Incomplete radiofrequency ablation promotes the development of CD133(+) cancer stem cells in hepatocellular carcinoma cell line HepG2 via inducing SOX9 expression

Simultaneous inhibition of heat shock proteins and autophagy enhances radiofrequency ablation of hepatocellular carcinoma

Radiofrequency ablation (RFA) is a commonly used minimally invasive treatment for hepatocellular carcinoma (HCC). However, incomplete radiofrequency ablation (iRFA) promotes tumor progression and metastasis. There is an urgent need to develop innovative strategies to enhance the efficacy of iRFA. The upregulation of heat shock proteins (HSPs) and activation of protective autophagy in tumor cells upon exposure to sublethal heat enhance the thermotolerance, thereby promoting tumor cell survival. Here, 3-methyladenine (3-MA) and lonidamine (LND) co-encapsulated liposomes (Lip@LND/3-MA) are designed to enhance the efficacy of iRFA by simultaneous inhibition of glycolysis and autophagy. On one hand, LND inhibits hexokinase, a key enzyme in glycolysis, and thus reduces ATP production and consequently suppresses the expression of HSPs. On the other hand, 3-MA, as an autophagy inhibitor, can inhibit protective autophagy after iRFA. Lip@LND/3-MA is confirmed to suppress the expression of HSPs and reduce the autophagy level during RFA. Therefore, the thermotolerance of tumor cells is significantly weakened, leading to remarkably enhanced therapeutic efficacy of iRFA. It is believed that simultaneous inhibition of HSPs and autophagy is a promising therapeutic strategy in clinical practice of RFA.

Radiofrequency ablation: mechanisms and clinical applications

Radiofrequency ablation (RFA), a form of thermal ablation, employs localized heat to induce protein denaturation in tissue cells, resulting in cell death. It has emerged as a viable treatment option for patients who are ineligible for surgery in various diseases, particularly liver cancer and other tumor-related conditions. In addition to directly eliminating tumor cells, RFA also induces alterations in the infiltrating cells within the tumor microenvironment (TME), which can significantly impact treatment outcomes. Moreover, incomplete RFA (iRFA) may lead to tumor recurrence and metastasis. The current challenge is to enhance the efficacy of RFA by elucidating its underlying mechanisms. This review discusses the clinical applications of RFA in treating various diseases and the mechanisms that contribute to the survival and invasion of tumor cells following iRFA, including the roles of heat shock proteins, hypoxia, and autophagy. Additionally, we analyze‌ the changes occurring in infiltrating cells within the TME after iRFA. Finally, we provide a comprehensive summary of clinical trials involving RFA in conjunction with other treatment modalities in the field of cancer therapy, aiming to offer novel insights and references for improving the effectiveness of RFA.

Sox9: A potential regulator of cancer stem cells in osteosarcoma

Osteosarcoma is a highly aggressive bone tumor primarily affecting children and adolescents. Despite advancements in treatment modalities, the prognosis for osteosarcoma patients remains poor, emphasizing the need for a deeper understanding of its underlying mechanisms. In recent years, the concept of cancer stem cells (CSCs) has emerged as a crucial factor in tumor initiation, progression, and therapy resistance. These specialized subpopulations of cells possess self-renewal capacity, tumorigenic potential, and contribute to tumor heterogeneity. Sox9, a transcription factor known for its critical role in embryonic development and tissue homeostasis, has been implicated in various malignancies, including osteosarcoma. This review aims to summarize the current knowledge regarding the role of Sox9 in CSCs in osteosarcoma and its potential implications as a prognosis and therapeutic target.

Sublethal thermal stress promotes migration and invasion of thyroid cancer cells

OBJECTIVE

Radiofrequency ablation is a viable option in the treatment of benign thyroid nodules. Some reports suggest that thermal ablation may also be safe for the management of low-risk thyroid cancer. In this study, we applied transient heat treatment to thyroid cancer cells to mimic clinical scenarios in which insufficient ablation leads to incomplete eradication of thyroid cancer.

METHODS

Differentiated thyroid cancer cell lines B-CPAP, TPC-1, and FTC-133 were subjected to heat treatment at different temperatures for 10 min. Effects on cell growth, clonogenicity, wound healing assay, and Transwell invasion were determined.

RESULTS

Heat treatment at 45°C or higher reduced cell growth, whereas viability of thyroid cancer cells was not changed after heat treatment at 37, 40, or 42°C. Heat treatment at 40°C increased the number of colony formations by 16% to 39%. Additionally, transient heat treatment at 40°C resulted in a 1.75-fold to 2.56-fold higher migratory activity than treatment at 37°C. Invasive capacity was increased after heat treatment, ranging from 115% to 126%. Expression of several epithelial-mesenchymal transition markers, including ZEB1, N-cadherin, and MMP2, was upregulated following heat treatment at 40°C.

CONCLUSION

We for the first time demonstrate that sublethal thermal stress may increase clonogenicity, migration, and invasion of thyroid cancer cells.

Mechanisms and therapeutic strategies to combat the recurrence and progression of hepatocellular carcinoma after thermal ablation

Thermal ablation (TA), including radiofrequency ablation (RFA) and microwave ablation (MWA), has become the main treatment for early-stage hepatocellular carcinoma (HCC) due to advantages such as safety and minimal invasiveness. However, HCC is prone to local recurrence, with more aggressive malignancies after TA closely related to TA-induced changes in epithelial-mesenchymal transition (EMT) and remodeling of the tumor microenvironment (TME). According to many studies, various components of the TME undergo complex changes after TA, such as the recruitment of innate and adaptive immune cells, the release of tumor-associated antigens (TAAs) and various cytokines, the formation of a hypoxic microenvironment, and tumor angiogenesis. Changes in the TME after TA can partly enhance the anti-tumor immune response; however, this response is weak to kill the tumor completely. Certain components of the TME can induce an immunosuppressive microenvironment through complex interactions, leading to tumor recurrence and progression. How the TME is remodeled after TA and the mechanism by which the TME promotes HCC recurrence and progression are unclear. Thus, in this review, we focused on these issues to highlight potentially effective strategies for reducing and preventing the recurrence and progression of HCC after TA.

Incomplete radiofrequency ablation induced chemoresistance by up-regulating heat shock protein 70 in hepatocellular carcinoma

Radiofrequency ablation (RFA) is a common minimally invasive treatment for hepatocellular carcinoma (HCC). Incomplete RFA (iRFA) due to the sub-lethal heat shock challenge of some cell populations leads to the generation of transformed survivor cells with enhanced chemoresistance. However, the underlying mechanism of iRFA on HCCs chemoresistance remains unknown. In the present study, we investigated the effect of iRFA on HCCs sensitivity to cisplatin. Cells treated with the sub-lethal heat shock challenge were used to mimic iRFA treatment in vitro. An orthotopic implantation HCC model was established and also performed iRFA treatment. Flow cytometry, transwell assay, and cell counting kit-8 assay were used to determine the effect of iRFA treatment on cisplatin-induced HCC cell apoptosis, invasion, and cell viability. ELISA and Western blot were used to detect the effect of iRFA treatment on cisplatin-induced HCC cell pyroptosis. We found that iRFA treatment increased the HCC cell proliferation and invasion ability, and inhibited cisplatin-induced pyroptosis. Further experiments showed that iRFA treatment induced upregulation of HSP70, which inhibited the cisplatin-induced NLRP3 inflammasome activation, leading to inhibition of pyroptosis. HSP70 knockdown or NLRP3 overexpression could reverse the effect of iRFA treatment in vitro. In vivo, HSP70 knockdown reversed the chemosensitivity of HCC to cisplatin, which was decreased by iRFA. In conclusion, we demonstrated that iRFA induced drug resistance by HSP70-mediated inhibition of cell pyroptosis in HCC.

Long-term Outcomes of Transcatheter Arterial Chemoembolization Combined With Radiofrequency Ablation as an Initial Treatment for Early-Stage Hepatocellular Carcinoma

IMPORTANCE

The long-term outcomes of transcatheter arterial chemoembolization (TACE) combined with radiofrequency ablation (RFA) are not determined.

OBJECTIVE

To report the long-term outcomes of TACE-RFA.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study analyzed long-term follow-up data from a phase 3 randomized clinical trial of adults with early HCC conducted from October 2006 to June 2009. Participants were randomly assigned to the TACE-RFA group or the RFA group in a 1:1 ratio and followed up approximately 6 years after the trial was closed. Data analysis was performed March 2020.

EXPOSURE

In the TACE-RFA group, TACE was performed first, and RFA was done 2 weeks later.

MAIN OUTCOMES AND MEASURES

Overall survival (OS) and recurrence-free survival (RFS).

RESULTS

Of 189 patients who were included (mean [SD] age, 54.3 [12.0] years; 146 [77.2%] men), 94 and 95 patients were assigned to the TACE-RFA group and RFA group, respectively, with their baseline characteristics well matched. Three patients in each group were lost to follow-up. The 5-year and 7-year OS rates for the TACE-RFA group vs the RFA group were 52.0% and 36.4% vs 43.2% and 19.4%, respectively (hazard ratio [HR], 0.55; 95% CI, 0.39-0.78; P = .001). The 5-year and 7-year RFS rates for the TACE-RFA group vs the RFA group were 41.4% and 34.5% vs 27.4% and 18.1%, respectively (HR, 0.66; 95% CI, 0.49-0.89; P = .007). On subgroup analysis comparing patients who had tumors larger than 3 cm with those who had tumors 3 cm or smaller, the OS and RFS survival rates in the TACE-RFA group (HR, 3.20; 95% CI, 1.91-5.35, P < .001) were significantly better than those in the RFA group (HR, 2.03; 95% CI, 1.30-3.17; P = .002).

CONCLUSIONS AND RELEVANCE

In this cohort study, combined RFA and TACE was associated with better survival than RFA alone on long-term follow-up. Patients with tumors 3 cm or smaller did not benefit as well as patients with tumors larger than 3 cm from the combined treatment.

Insufficient Radiofrequency Ablation Promotes Hepatocellular Carcinoma Metastasis Through N6-Methyladenosine mRNA Methylation-Dependent Mechanism

BACKGROUND AND AIMS

The dynamic N6-methyladenosine (m⁶ A) mRNA modification is essential for acute stress response and cancer progression. Sublethal heat stress from insufficient radiofrequency ablation (IRFA) has been confirmed to promote HCC progression; however, whether m⁶ A machinery is involved in IRFA-induced HCC recurrence remains open for study.

APPROACH AND RESULTS

Using an IRFA HCC orthotopic mouse model, we detected a higher level of m⁶ A reader YTH N6-methyladenosine RNA binding protein 1-3 (YTHDF1) in the sublethal-heat-exposed transitional zone close to the ablation center than that in the farther area. In addition, we validated the increased m⁶ A modification and elevated YTHDF1 protein level in sublethal-heat-treated HCC cell lines, HCC patient-derived xenograft (PDX) mouse model, and patients' HCC tissues. Functionally, gain-of-function/loss-of-function assays showed that YTHDF1 promotes HCC cell viability and metastasis. Knockdown of YTHDF1 drastically restrains the tumor metastasis evoked by sublethal heat treatment in tail vein injection lung metastasis and orthotopic HCC mouse models. Mechanistically, we found that sublethal heat treatment increases epidermal factor growth receptor (EGFR) m⁶ A modification in the vicinity of the 5' untranslated region and promotes its binding with YTHDF1, which enhances the translation of EGFR mRNA. The sublethal-heat-induced up-regulation of EGFR level was further confirmed in the IRFA HCC PDX mouse model and patients' tissues. Combination of YTHDF1 silencing and EGFR inhibition suppressed the malignancies of HCC cells synergically.

CONCLUSIONS

The m⁶ A-YTHDF1-EGFR axis promotes HCC progression after IRFA, supporting the rationale for targeting m⁶ A machinery combined with EGFR inhibitors to suppress HCC metastasis after RFA.

ATP-citrate lyase regulates stemness and metastasis in hepatocellular carcinoma via the Wnt/β-catenin signaling pathway

BACKGROUND

Hepatocellular carcinoma (HCC) is one of the most highly malignant tumors. Liver tumor-initiating cells (LTICs) have been considered to contribute to HCC progression and metastasis. ATP-citrate lyase (ACLY), as a key enzyme for de novo lipogenesis, has been reported to be upregulated in various tumors. However, its expression and role in HCC and LTICs remain unknown.

METHODS

The expressions of ACLY in HCC tissues were detected by quantitative real-time PCR (qRT-PCR), Western blotting and immunohistochemistry. Kaplan-Meier curves and Chi-square test were used to determine the clinical significance of ACLY expression in HCC patients. A series of assays were performed to determine the function of ACLY on stemness, migration and invasion of HCC cells. Luciferase reporter assay, Western blotting and immunoprecipitation were used to study the regulation of the Wnt/β-catenin signaling by ACLY. Rescue experiments were performed to investigate whether β-catenin was the mediator of ACLY-regulated stemness and migration in HCC cells.

RESULTS

ACLY was highly expressed in HCC tissues and LTICs. Overexpression of ACLY was significantly correlated with poor prognosis, progression and metastasis of HCC patients. Knockdown of ACLY remarkably suppressed stemness properties, migration and invasion in HCC cells. Mechanistically, ACLY could regulate the canonical Wnt pathway by affecting the stability of β-catenin, and Lys49 acetylation of β-catenin might mediate ACLY-regulated β-catenin level in HCC cells.

CONCLUSIONS

ACLY is a potent regulator of Wnt/β-catenin signaling in modulating LTICs stemness and metastasis in HCC. ACLY may serve as a new target for the diagnosis and treatment of HCC.

An aptamer-based drug delivery agent (CD133-apt-Dox) selectively and effectively kills liver cancer stem-like cells

Liver cancer has no effective therapies, hence a poor survival. Cancer stem-like cells not only contribute to cancer initiation and progression, but also to drug resistance, cancer metastasis, and eventually treatment failure. Hence, any approaches that can effectively kill cancer stem-like cells hold a great potential for cancer treatment. CD133 is a robust marker for liver cancer stem-like cells. We developed a specific aptamer against CD133 (CD133-apt), and then loaded this aptamer with an anticancer drug doxorubicin (CD133-apt-Dox). The efficacy of CD133-apt-Dox in targeting liver cancer stem-like cells and its overall effect in treating liver cancer were investigated using multiple in vitro and in vivo studies including in patients-derived liver cancer organoids. We have observed that CD133-apt could preferably delivered doxorubicin to CD133-expressing cells with efficient drug accumulation and retention. CD133-apt-Dox impaired the self-renewal capacity of liver cancer stem-like cells and attenuated their stem-ness phenotypes in vitro or in vivo. CD133-apt-Dox significantly inhibited the growth of liver cancer cells and patients-derived organoids and reduced the growth of xenograft tumours in nude mice inhibited the growth of DEN-induced liver cancer in immunocompetent mice. Hence, aptamer-mediated targeting of CD133 is a highly promising approach for liver cancer therapy.

c-Met/MAPK pathway promotes the malignant progression of residual hepatocellular carcinoma cells after insufficient radiofrequency ablation

Radiofrequency ablation (RFA) is popularly used in the treatment of hepatocellular carcinoma (HCC). However, the accelerated malignant progression of residual HCC cells after RFA is the main obstacle for the application of this technology in HCC treatment. In the present study, HepG2 cells, an established human HCC cell line, experienced repeatedly with heat treatment, survived cells, HepG2-H cells, were used to simulate residual HCC cells after RFA. The abilities of proliferation, colony formation, and migration were compared between HepG2 and HepG2-H cells. Then, RNA sequencing was used to explore the difference in genes expression between two groups of cells. Subsequently, the level of c-Met, one of membranous receptors of MAPK signal pathway, was measured by RT-qPCR and western blot; the effect of c-Met inhibition on the malignant progression of HepG2-H cells was evaluated. The results showed that HepG2-H cells exhibited higher abilities in the proliferation, colony formation, and migration than that of HepG2 cells. Moreover, differentially expressed genes between two groups of cells were prominently enriched in MAPK signal pathway. The level of c-Met in HepG2-H cells was significantly higher than that in HepG2 cells, and the inhibition in the activity of c-Met could repress the malignant behaviors of HepG2-H cells. These results indicated that the accelerated malignant progression of residual HCC cells after RFA can be partly attributed to the overexpression of c-Met and the activation of MAPK signal pathway. Therefore, we proposed that RFA followed by c-Met inhibitor intake maybe is a better treatment protocol for HCC.

Genomic DNA methylation profiling indicates immune response following thermal ablation treatment for HBV-associated hepatocellular carcinoma

Hepatitis B virus (HBV)-associated hepatocellular carcinoma (HCC) is the most common type of liver cancer in China. Thermal ablation is one of the main strategies for HCC treatment. However, few studies have investigated the properties of the immune response following thermal ablation thus far. In the present study, five subjects with HBV-associated HCC were recruited from The Beijing Youan Hospital. Peripheral blood mononuclear cells (PBMCs) were collected at three time points: Prior to thermal ablation (PR), 1-3 days post-ablation (P1) and 5-7 days post-ablation (P7). An Illumina 850K methylation microarray was employed to determine the DNA methylation profile of each sample. Data were analyzed using different methylation probes with the Bioconductor package in R. Following annotation of different methylation CG sites (CGs), the associated genes were subjected to an Ingenuity Pathway Analysis. A total of 3,000 significantly different CGs (adjusted P<0.05; |log(fold-change)|>0.5) were identified within the PR, P1 and P7 time points. Of these, 744 (24.8%) sites increased between the PR and P1 time points but gradually decreased at the P7 time point. The remaining 2,256 (75.2%) sites decreased between the PR and P1 time points gradually increased at the P7 time point. Following gene annotation of different CGs on the promoter, signaling pathways analysis demonstrated that 'p70S6K signaling', 'CXCR4 signaling', 'dendritic cell maturation', 'production of nitric oxide and reactive oxygen species in macrophages' pathways were activated at the P7 time point. The present study suggested that PBMC DNA methylation had changed soon after thermal ablation for subjects with HBV-associated HCC, and systemic immune responses were activated, particularly at the P7 time point.

Novel ablation methods for treatment of gliomas

Primary brain tumors are among the deadliest cancers that remain highly incurable. A need exists for new approaches to tumor therapy that can circumvent the blood brain barrier (BBB), target highly resistant tumors and cancer stem-like cells (CSCs) as well create an anti-cancer immunomodulatory environment. Successful treatments may also require a combinatory approach utilizing surgery, chemotherapy, radiation and novel ablation strategies that can both eliminate the bulk tumor and prevent any potential residual CSCs from propagating in the resected tissue. A number of thermal and non-thermal ablation methods have been developed and tested, which have gained much enthusiasm for the treatment of brain tumors. Here we review the most common primary brain tumors and the candidate ablation methods for targeting the tumor and its microenvironment.