Sequence of a fusogenic herpes simplex virus, RH2, for oncolytic virotherapy

Molecular and immune targets in cutaneous squamous cell carcinoma

Cutaneous squamous cell carcinoma (cSCC) is the second most common skin cancer and often confers a good prognosis. Though surgery is the gold standard of treatment, unresectable or metastatic disease can necessitate systemic therapy. Of systemic agents, there is increasing interest in the use of immunotherapies and targeted therapy. Further study into the driver mutations in cSCC has identified opportunities for targeted therapy. In this review, we discuss both current and investigational immune and molecular targets of therapy for cSCC.

Proteomic Analysis of Secretomes of Oncolytic Herpes Simplex Virus-Infected Squamous Cell Carcinoma Cells

Oncolytic herpes simplex virus type 1 (HSV-1) strain RH2 induced immunogenic cell death (ICD) with the release and surface exposure of damage-associated molecular patterns (DAMPs) in squamous cell carcinoma (SCC) SCCVII cells. The supernatants of RH2-infected SCCVII cells also exhibited antitumor ability by intratumoral administration in SCCVII tumor-bearing mice. The supernatants of RH2-infected cells and mock-infected cells were concentrated to produce Med24 and MedC for proteomic analyses. In Med24, the up- and down-regulated proteins were observed. Proteins including filamin, tubulin, t-complex protein 1 (TCP-1), and heat shock proteins (HSPs), were up-regulated, while extracellular matrix (ECM) proteins were markedly down-regulated. Viral proteins were detected in Med 24. These results indicate that HSV-1 RH2 infection increases the release of danger signal proteins and viral gene products, but decreases the release of ECM components. These changes may alter the tumor microenvironment (TME) and contribute to enhancement of anti-tumor immunity against SCC.

Role of autophagy in oncolytic herpes simplex virus type 1-induced cell death in squamous cell carcinoma cells

Herpes simplex virus type 1 (HSV-1) is one of the most widely studied viruses for oncolytic virotherapy. In squamous cell carcinoma (SCC) cells, the role of autophagy induced by neurovirulence gene-deficient HSV-1s in programmed cell death has not yet been elucidated. The oncolytic HSV-1 strain RH2, which lacks the γ34.5 gene and induces the fusion of human SCC cells, was used. RH2 replicated and induced cell death in SCC cells. RH2 infection was accompanied by the aggregation of microtubule-associated protein 1 light chain 3 (LC3) in the cytoplasm, the conversion of LC3-I to LC3-II and the formation of double-membrane vacuoles containing cell contents. No significant changes were observed in the expression of Bcl-2 or Bax, while a slight decrease was observed in that of Beclin 1. The autophagy inhibitors, 3-methyladenine (3-MA) and bafilomycin A1, did not affect viral replication, but significantly inhibited the cytotoxicity of RH2. The caspase-3 inhibitor z-DEVD-fmk and caspase-1 inhibitor z-YVAD-fmk also reduced the cytotoxicity of RH2. These results demonstrated that γ34.5 gene-deficient HSV-1 RH2 induced autophagic cell death in SCC cells as well as pyroptosis and apoptosis.

Presage of oncolytic virotherapy for oral cancer with herpes simplex virus

A virus is a pathogenic organism that causes a number of infectious diseases in humans. The oral cavity is the site at which viruses enter and are excreted from the human body. Herpes simplex virus type 1 (HSV-1) produces the primary infectious disease, gingivostomatitis, and recurrent disease, labial herpes. HSV-1 is one of the most extensively investigated viruses used for cancer therapy. In principle, HSV-1 infects epithelial cells and neuronal cells and exhibits cytotoxicity due to its cytopathic effects on these cells. If the replication of the virus occurs in tumor cells, but not normal cells, the virus may be used as an antitumor agent. Therefore, HSV-1 genes have been modified by genetic engineering, and in vitro and in vivo studies with the oncolytic virus have demonstrated its efficiency against head and neck cancer including oral cancer. The oncolytic abilities of other viruses such as adenovirus and reovirus have also been demonstrated. In clinical trials, HSV-1 is the top runner and is now available for the treatment of patients with advanced melanoma. Thus, melanoma in the oral cavity is the target of oncolytic HSV-1. Oncolytic virotherapy is a hopeful and realistic modality for the treatment of oral cancer.

De Novo Assembly of Human Herpes Virus Type 1 (HHV-1) Genome, Mining of Non-Canonical Structures and Detection of Novel Drug-Resistance Mutations Using Short- and Long-Read Next Generation Sequencing Technologies

Human herpesvirus type 1 (HHV-1) has a large double-stranded DNA genome of approximately 152 kbp that is structurally complex and GC-rich. This makes the assembly of HHV-1 whole genomes from short-read sequencing data technically challenging. To improve the assembly of HHV-1 genomes we have employed a hybrid genome assembly protocol using data from two sequencing technologies: the short-read Roche 454 and the long-read Oxford Nanopore MinION sequencers. We sequenced 18 HHV-1 cell culture-isolated clinical specimens collected from immunocompromised patients undergoing antiviral therapy. The susceptibility of the samples to several antivirals was determined by plaque reduction assay. Hybrid genome assembly resulted in a decrease in the number of contigs in 6 out of 7 samples and an increase in N(G)50 and N(G)75 of all 7 samples sequenced by both technologies. The approach also enhanced the detection of non-canonical contigs including a rearrangement between the unique (UL) and repeat (T/IRL) sequence regions of one sample that was not detectable by assembly of 454 reads alone. We detected several known and novel resistance-associated mutations in UL23 and UL30 genes. Genome-wide genetic variability ranged from <1% to 53% of amino acids in each gene exhibiting at least one substitution within the pool of samples. The UL23 gene had one of the highest genetic variabilities at 35.2% in keeping with its role in development of drug resistance. The assembly of accurate, full-length HHV-1 genomes will be useful in determining genetic determinants of drug resistance, virulence, pathogenesis and viral evolution. The numerous, complex repeat regions of the HHV-1 genome currently remain a barrier towards this goal.

Immunogenic cell death by oncolytic herpes simplex virus type 1 in squamous cell carcinoma cells

Molecules essential for the induction of immunogenic cell death (ICD) are called damage-associated molecular patterns (DAMPs). The effects of oncolytic herpes simplex virus type 1 (HSV-1) on the production of DAMPs were examined in squamous cell carcinoma (SCC) cells. The cytopathic effects of HSV-1 RH2 were observed in mouse SCCVII cells infected at a high multiplicity of infection (MOI), and the amounts of viable cells were decreased. After being infected with RH2, ATP and high mobility group box 1 (HMGB1) were released extracellulary, while calreticulin (CRT) translocated to the cell membrane. A flow-cytometric analysis revealed an increase in the number of annexin-V and propidium iodide (PI)-stained cells; and the amount of cleaved poly (ADP-ribose) polymerase (PARP) was increased. The killing effect of RH2 was reduced by pan-caspase inhibitor z-VAD-fmk and the caspase-1 inhibitor z-YVAD-fmk, suggesting the involvement of apoptosis and pyroptosis. In C3H mice bearing synergic SCCVII tumors, the growth of tumors injected with the supernatant of RH2-infected cells was less than that of tumors injected with phosphate-buffered saline (PBS). These results indicate that oncolytic HSV-1 RH2 produces DAMPs from SCC cells to induce cell death. This may contribute to the enhancement of tumor immunity by oncolytic HSV-1.

Entry of Oncolytic Herpes Simplex Virus into Human Squamous Cell Carcinoma Cells by Ultrasound

Low-intensity ultrasound is a useful method to introduce materials into cells due to the transient formation of micropores, called sonoporations, on the cell membrane. Whether oncolytic herpes simplex virus type 1 (HSV-1) can be introduced into oral squamous cell carcinoma (SCC) cells through membrane pores remains undetermined. Human SCC cell line SAS and oncolytic HSV-1 RH2, which was deficient in the 134.5 gene and fusogenic, were used. Cells were exposed to ultrasound in the presence or absence of microbubbles. The increase of virus entry was estimated by plaque numbers. Viral infection was hardly established without the adsorption step, but plaque number was increased by the exposure of HSV-1-inoculated cells to ultrasound. Plaque number was also increased even if SAS cells were exposed to ultrasound and inoculated with RH2 without the adsorption step. This effect was abolished when the interval from ultrasound exposure to virus inoculation was prolonged. Scanning electron microscopy revealed depressed spots on the cell surface after exposure to ultrasound. These results suggest that oncolytic HSV-1 RH2 can be introduced into SAS cells through ultrasound-mediated pores of the cell membrane that are resealed after an interval.

Ultrasound as a method to enhance antitumor ability of oncolytic herpes simplex virus for head and neck cancer

Low-intensity ultrasound is a useful method to enhance the delivery of drugs to target cells via a range of mechanisms including the transient formation of micropores in the cell membrane, a process known as sonoporation. The effect of ultrasound on oncolytic herpes simplex virus type-1 (HSV-1) infection in oral squamous cell carcinoma (SCC) was examined. Human SCC cell line SAS and oncolytic HSV-1 RH2, which was deficient in the neurovirulent γ134.5 gene and exhibited cell fusion actions, were used. Cells grown in multi-well plates were infected with HSV-1 and exposed to ultrasound in the presence or absence of microbubbles after an adsorption period. The number of plaques was significantly greater than that of the untreated control. SAS cells were inoculated subcutaneously into nude mice and tumors were produced. Tumors were injected with HSV-1 RH2 with or without microbubbles and then exposed to ultrasound through the covering skin. The amount of the virus in tumor tissues 3 days after the injection was higher in tumors treated with HSV-1 RH2 and ultrasound than in tumors treated with RH2 only. The expression of the HSV-1 antigen was also increased by ultrasound and microbubbles. Tumor growth was suppressed with HSV-1 RH2 in combination with ultrasound, especially with microbubbles. These results indicated that ultrasound increased the efficiency of the HSV-1 infection in SAS cells and nude mouse tumors. This method can potentially be useful to enhance the antitumor effects of oncolytic HSV-1 on head and neck cancer treatment.