The role of JNK phosphorylation as a molecular target to enhance adenovirus replication, oncolysis and cancer therapeutic efficacy

Enhancing the Antitumor Efficacy of Oncolytic Adenovirus Through Sonodynamic Therapy-Augmented Virus Replication

The therapeutic efficacy of oncolytic adenoviruses (OAs) relies on efficient viral transduction and replication. However, the limited expression of coxsackie-adenovirus receptors in many tumors, along with the intracellular antiviral signaling, poses significant obstacles to OA infection and oncolysis. Here, we present sonosensitizer-armed OAs (saOAs) that potentiate the antitumor efficacy of oncolytic virotherapy through sonodynamic therapy-augmented virus replication. The saOAs could not only efficiently infect tumor cells via transferrin receptor-mediated endocytosis but also exhibit enhanced viral replication and tumor oncolysis under ultrasound irradiation. We revealed that the sonosensitizer loaded on the viruses induced the generation of ROS within tumor cells, which triggered JNK-mediated autophagy, ultimately leading to the enhanced viral replication. In mouse models of malignant melanoma, the combination of saOAs and sonodynamic therapy elicited a robust antitumor immune response, resulting in significant inhibition of melanoma growth and improved host survival. This work highlights the potential of sonodynamic therapy in enhancing the effectiveness of OAs and provides a promising platform for fully exploiting the antitumor efficacy of oncolytic virotherapy.

Nanoparticles augment the therapeutic window of RT and immunotherapy for treating cancers: pivotal role of autophagy

Immunotherapies are now emerging as an efficient anticancer therapeutic strategy. Cancer immunotherapy utilizes the host's immune system to fight against cancer cells and has gained increasing interest due to its durable efficacy and low toxicity compared to traditional antitumor treatments, such as chemotherapy and radiotherapy (RT). Although the combination of RT and immunotherapy has drawn extensive attention in the clinical setting, the overall response rates are still low. Therefore, strategies for further improvement are urgently needed. Nanotechnology has been used in cancer immunotherapy and RT to target not only cancer cells but also the tumor microenvironment (TME), thereby helping to generate a long-term immune response. Nanomaterials can be an effective delivery system and a strong autophagy inducer, with the ability to elevate autophagy to very high levels. Interestingly, autophagy could play a critical role in optimal immune function, mediating cell-extrinsic homeostatic effects through the regulation of danger signaling in neoplastic cells under immunogenic chemotherapy and/or RT. In this review, we summarize the preclinical and clinical development of the combination of immunotherapy and RT in cancer therapy and highlight the latest progress in nanotechnology for augmenting the anticancer effects of immunotherapy and RT. The underlying mechanisms of nanomaterial-triggered autophagy in tumor cells and the TME are discussed in depth. Finally, we suggest the implications of these three strategies combined together to achieve the goal of maximizing the therapeutic advantages of cancer therapy and show recent advances in biomarkers for tumor response in the evaluation of those therapies.

Autophagy-related signaling pathways are involved in cancer (Review)

Autophagy is a self-digestion process in cells that can maintain energy homeostasis under normal circumstances. However, misfolded proteins, damaged mitochondria and other unwanted components in cells can be decomposed and reused via autophagy in some specific cases (including hypoxic stress, low energy states or nutrient deprivation). Therefore, autophagy serves a positive role in cell survival and growth. However, excessive autophagy may lead to apoptosis. Furthermore, abnormal autophagy may lead to carcinogenesis and promote tumorigenesis in normal cells. In tumor cells, autophagy may provide the energy required for excessive proliferation, promote the growth of cancer cells, and evade apoptosis caused by certain treatments, including radiotherapy and chemotherapy, resulting in increased treatment resistance and drug resistance. On the other hand, autophagy leads to an insufficient nutrient supply in cancer cells and the destruction of energy homeostasis, thereby inducing cancer cell apoptosis. Therefore, understanding the mechanism of the double-edged sword of autophagy is crucial for the treatment of cancer. The present review summarizes the signaling pathways and key factors involved in autophagy and cancer to provide possible strategies for treating tumors.

Bone and Soft-Tissue Sarcoma: A New Target for Telomerase-Specific Oncolytic Virotherapy

Adenovirus serotype 5 (Ad5) is widely and frequently used as a virus vector in cancer gene therapy and oncolytic virotherapy. Oncolytic virotherapy is a novel antitumor treatment for inducing lytic cell death in tumor cells without affecting normal cells. Based on the Ad5 genome, we have generated three types of telomerase-specific replication-competent oncolytic adenoviruses: OBP-301 (Telomelysin), green fluorescent protein (GFP)-expressing OBP-401 (TelomeScan), and tumor suppressor p53-armed OBP-702. These viruses drive the expression of the adenoviral E1A and E1B genes under the control of the hTERT (human telomerase reverse transcriptase-encoding gene) promoter, providing tumor-specific virus replication. This review focuses on the therapeutic potential of three hTERT promoter-driven oncolytic adenoviruses against bone and soft-tissue sarcoma cells with telomerase activity. OBP-301 induces the antitumor effect in monotherapy or combination therapy with chemotherapeutic drugs via induction of autophagy and apoptosis. OBP-401 enables visualization of sarcoma cells within normal tissues by serving as a tumor-specific labeling reagent for fluorescence-guided surgery via induction of GFP expression. OBP-702 exhibits a profound antitumor effect in OBP-301-resistant sarcoma cells via activation of the p53 signaling pathway. Taken together, telomerase-specific oncolytic adenoviruses are promising antitumor reagents that are expected to provide novel therapeutic options for the treatment of bone and soft-tissue sarcomas.