Suppression of bone metastatic castration-resistant prostate cancer cell growth by a suicide gene delivered by JC polyomavirus-like particles.

Prostate cancer is one of the most common cancers in men. The heterogeneity and mutations exhibited by prostate cancer cells often results in the progression to incurable metastatic castration-resistant prostate cancer (mCRPC). Our previous investigations demonstrated that the virus-like particles (VLPs) of JC polyomavirus (JCPyV) can deliver exogenous genes to prostate cancer cells for expression. JCPyV VLPs packaging pPSAtk (PSAtk-VLPs) possess the ability to transcriptionally target and selectively induce cytotoxicity in prostate cancer cells in vitro and in vivo, as pPSAtk can only express the thymidine kinase gene, a suicide gene, in androgen receptor-positive cells. To further investigate whether PSAtk-VLPs inhibit the growth of metastasized prostate cancer cells, we established an animal model of bone-metastatic prostate cancer to compare PSAtk-VLPs with leuprorelin acetate and enzalutamide, hormonal agents commonly used in clinical settings, and investigated the effectiveness of PSAtk-VLPs. In the present study, we observed that PSAtk-VLPs effectively inhibited the growth of prostate cancer cells that had metastasized to the bone in the metastatic animal model. In addition, PSAtk-VLPs showed a higher effectiveness than hormone therapy in this animal model study. These results suggest that PSAtk-VLPs may serve as a treatment option for mCRPC therapy in the future.

Histone deacetylase III interactions with BK polyomavirus large tumor antigen may affect protein stability.

BACKGROUND: Human polyomavirus BK (BKPyV) causes associated nephropathy and contributes to urinary tract cancer development in renal transplant recipients. Large tumor antigen (LT) is an early protein essential in the polyomavirus life cycle. Protein acetylation plays a critical role in regulating protein stability, so this study investigated the acetylation of the BKPyV LT protein. METHODS: The BKPyV LT nucleotide was synthesized, and the protein was expressed by transfection into permissive cells. The BKPyV LT protein was immunoprecipitated and subjected to LC-MS/MS analysis to determine the acetylation residues. The relative lysine was then mutated to arginine in the LT nucleotide and BKPyV genome to analyze the role of LT lysine acetylation in the BKPyV life cycle. RESULTS: BKPyV LT acetylation sites were identified at Lys3 and Lys230 by mass spectrometry. HDAC3 and HDAC8 and their deacetylation activity are required for BKPyV LT expression. In addition, mutations of Lys3 and Lys230 to arginine increased LT expression, and the interaction of HDAC3 and LT was confirmed by coimmunoprecipitation. CONCLUSIONS: HDAC3 is a newly identified protein that interacts with BKPyV LT, and LT acetylation plays a vital role in the BKPyV life cycle.

Reversine induces autophagic cell death through the AMP-activated protein kinase pathway in urothelial carcinoma cells.

Urothelial carcinoma is one of the most common malignancies of the urinary tract. Effective treatment of advanced urothelial carcinoma remains a clinical challenge with poor outcomes in these patients. Previous reports have shown that the expression of aurora kinase is associated with clinical stage and prognosis; hence, aurora kinases are potential targets in urothelial carcinoma therapy. Reversine, an aurora kinase inhibitor, was analyzed for its cytotoxicity in this study. Cell proliferation, flow cytometry, western blotting, and immunofluorescent assay were used to determine the effect of reversine on urothelial carcinoma cells. The results showed that reversine significantly inhibits the growth of urothelial carcinoma cell lines. Reversine induced cell cycle arrest at the G2/M phase, leading to autophagic cell death by activating the AMP-activated protein kinase pathway. Reversine induced significant cell death in urothelial carcinoma cells. Our results suggest that reversine may be a suitably small molecule for treating urothelial carcinoma in the future.

Inhibition of human diffuse large B-cell lymphoma growth by JC polyomavirus-like particles delivering a suicide gene.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is one of the most common types of aggressive B-cell non-Hodgkin lymphoma. About one-third of patients are either refractory to the treatment or experience relapse afterwards, pointing to the necessity of developing other effective therapies for DLBCL. Human B-lymphocytes are susceptible to JC polyomavirus (JCPyV) infection, and JCPyV virus-like particles (VLPs) can effectively deliver exogenous genes to susceptible cells for expression, suggesting the feasibility of using JCPyV VLPs as gene therapy vectors for DLBCL. METHODS: The JCPyV VLPs packaged with a GFP reporter gene were used to infect human DLBCL cells for gene delivery assay. Furthermore, we packaged JCPyV VLPs with a suicide gene encoding thymidine kinase (TK) to inhibit the growth of DLBCL in vitro and in vivo. RESULTS: Here, we show that JCPyV VLPs effectively entered human germinal center B-cell-like (GCB-like) DLBCL and activated B-cell-like (ABC-like) DLBCL and expressed the packaged reporter gene in vitro. As measured by the MTT assay, treatment with tk-VLPs in combination with gancyclovir (GCV) reduced the viability of DLBCL cells by 60%. In the xenograft mouse model, injection of tk-VLPs through the tail vein in combination with GCV administration resulted in a potent 80% inhibition of DLBCL tumor nodule growth. CONCLUSIONS: Our results demonstrate the effectiveness of JCPyV VLPs as gene therapy vectors for human DLBCL and provide a potential new strategy for the treatment of DLBCL.

Inhibition of human bladder cancer growth by a suicide gene delivered by JC polyomavirus virus-like particles in a mouse model.

PURPOSE: Bladder cancer is one of the most common cancers of the urinary tract. The poor 5-year survival rate of invasive bladder cancer represents a challenge for bladder cancer treatment. Previous studies demonstrated that human urothelial carcinoma is susceptible to infection by JC polyomavirus. We used JC polyomavirus virus-like particles to deliver genes into human urothelial carcinoma cells for possible therapeutic investigation. MATERIALS AND METHODS: Reporter plasmids (pEGFP-N3) for expressing green fluorescent protein, LacZ expression plasmids bearing cytomegalovirus or Muc1 promoter and a functional plasmid (pUMVC1-tk) for expressing thymidine kinase were packaged into JC polyomavirus virus-like particles. Plasmid DNAs were transduced via the JC polyomavirus virus-like particles into human urothelial carcinoma cells in vitro and into xenografted human bladder tumor nodules in vivo. RESULTS: pEGFP-N3 DNA was delivered and green fluorescent protein was expressed in human urothelial carcinoma cells in vitro and in the tumor nodules of mice in vivo. The thymidine kinase transgene also functioned in vitro and in vivo after JC polyomavirus virus-like particle transduction. The thymidine kinase gene transduced urothelial carcinoma nodules were drastically reduced in the presence of acyclovir. In addition, we noted selective Muc1-LacZ expression in human urothelial carcinoma cells transduced by JC polyomavirus virus-like particles. CONCLUSIONS: These findings provide a possible future approach to human urothelial carcinoma gene therapy using JC polyomavirus virus-like particles.

Inhibition of orthotopic castration-resistant prostate cancer growth and metastasis in mice by JC VLPs carrying a suicide gene driven by the PSA promoter.

Metastatic castration-resistant prostate cancer (mCRPC) is challenging to treat. Virus-like particles (VLPs), originating from JC polyomavirus (JCPyV) and carrying a suicide gene driven by the PSA promoter (PSAtk-VLPs), can inhibit tumor growth in animal models of human prostate cancer. However, the efficacy of suppression of orthotopic PCa growth and metastasis by PSAtk-VLPs remains undetermined. Here, we established an iRFP stable expression CRPC cell line suitable for deep-tissue observation using fluorescence molecular tomography (FMT). These cells were implanted into murine prostate tissue, and PSAtk-VLPs were systemically administered via the tail vein along with the prodrug ganciclovir (GCV), allowing for the real-time observation of orthotopic prostate tumor growth and CRPC tumor metastasis. Our findings demonstrated that systemic PSAtk-VLPs administration with GCV and subsequent FMT scanning facilitated real-time observation of the suppressed growth in mouse iRFP CRPC orthotopic tumors, which further revealed a notable metastasis rate reduction. Systemic PSAtk-VLPs and GCV administration effectively inhibited orthotopic prostate cancer growth and metastasis. These findings suggest the potential of JCPyV VLPs as a promising vector for mCRPC gene therapy. Conclusively, systemically administered JCPyV VLPs carrying a tissue-specific promoter, JCPyV VLPs can protect genes within the bloodstream to be specifically expressed in specific organs.

Artesunate Exhibits Synergy With Cisplatin and Cytotoxicity for Upper Tract and Bladder Urothelial Carcinoma Cells.

BACKGROUND/AIM: Urothelial carcinoma (UC) may arise from the urothelium of the upper tract and the bladder. Cisplatin-based therapy remains the gold standard for UC treatment. The poor 5-year survival rate of UC patients creates an urgent need to develop new drugs for advanced UC therapy. Artesunate (ART), a traditional Chinese medicine for treating malaria, is a potential anticancer agent, but its antigrowth effects on upper tract and bladder UC have not been investigated. MATERIALS AND METHODS: The antigrowth effect of ART in HT 1376 (bladder UC cells) and BFTC 909 [upper tract urothelial carcinoma (UTUC) cells] was determined by the CCK-8 assay. Flow cytometric analysis was used to evaluate the cell cycle distribution and apoptosis. The cell cycle, apoptosis, and autophagy-related protein expression were analyzed by western blotting. The efficacy of combination treatment with cisplatin was determined by the Calcusyn software. RESULTS: ART induced HT 1376 and BFTC 909 cell death in a concentration- and time-dependent manner, inducing G2/M cell-cycle arrest. ART induced apoptosis and redox imbalance in HT 1376 and BFTC 909 cells. Application of the reactive oxygen species (ROS) scavenger, N-acetyl-L-cysteine (NAC), attenuated cell death in ART-treated UC cells. BFTC 909 cells show a better response after ART treatment. CONCLUSION: ART may be a candidate drug for treating UTUC and bladder UC while increasing the therapeutic effect of cisplatin.

Recombined sequences between the non-coding control regions of JC and BK viruses found in the urine of a renal transplantation patient.

Kidney cells are the common host for JC virus (JCV) and BK virus (BKV). Reactivation of JCV and/or BKV in patients after organ transplantation, such as renal transplantation, may cause hemorrhagic cystitis and polyomavirus-associated nephropathy. Furthermore, JCV and BKV may be shed in the urine after reactivation in the kidney. Rearranged as well as archetypal non-coding control regions (NCCRs) of JCV and BKV have been frequently identified in human samples. In this study, three JC/BK recombined NCCR sequences were identified in the urine of a patient who had undergone renal transplantation. They were designated as JC-BK hybrids 1, 2, and 3. The three JC/BK recombinant NCCRs contain up-stream JCV as well as down-stream BKV sequences. Deletions of both JCV and BKV sequences were found in these recombined NCCRs. Recombination of DNA sequences between JCV and BKV may occur during co-infection due to the relatively high homology of the two viral genomes.

Auranofin induces urothelial carcinoma cell death via reactive oxygen species production and synergy with cisplatin.

Urothelial carcinoma (UC) is one of the most common cancer types of the urinary tract. UC is associated with poor 5-year survival rate, and resistance to cisplatin-based therapy remains a challenge for invasive bladder cancer treatment. Therefore, there is an urgent need to develop new drugs for advanced UC therapy. Auranofin (AF) was developed over 30 years ago for the treatment of rheumatoid arthritis and has been reported to exert an antitumor effect by increasing the level of reactive oxygen species (ROS) in cancer cells. The aim of the present study was to examine the effects of AF on cancer cell proliferation, cell cycle and apoptosis, either alone or in combination with cisplatin. AF induced cell death in two separate cell lines, HT 1376 and BFTC 909, in a concentration- and time-dependent manner by inducing cell cycle arrest. However, the distribution of cells in different phases of the cell cycle differed between the two cell lines, with G0/G1 cell cycle arrest in HT 1376 cells and S phase arrest in BFTC 909 cells. In addition, AF induced apoptosis in HT 1376, as well as redox imbalance in both HT 1376 and BFTC 909 cells. Cell viability was rescued following treatment with N-acetyl-L-cysteine, a ROS scavenger. Furthermore, AF treatment synergistically increased the cytotoxicity of HT 1376 and BFTC 909 cells when combined with cisplatin treatment. These findings suggest that AF may represent a potential candidate drug against UC and increase the therapeutic effect of cisplatin.

Unusually high incidence of polyomavirus JC infection in the higher grade of colorectal cancer tissues in Taiwan.

INTRODUCTION: The human JC polyomavirus (JCPyV) has been detected in colorectal cancer (CRC) tissues and is suggested to contribute to CRC tumorigenesis. The rearrangement of the JCPyV regulatory region is supposedly associated with CRC development. The progression of CRC involves the stepwise accumulation of mutations. The large tumor antigen (LT) of JCPyV can trigger uncontrolled cell cycle progression by targeting oncogenes, and tumor suppressor genes, and causing chromosome instability. Few studies have focused on the presence of JCPyV DNA in the higher grade of CRC tissues. METHODS: We collected 95 tissue blocks from samples of stages I, II, III, and IV CRC. Nested PCR targeting the regulatory region of the viral genome was performed to determine the presence of JCPyV DNA in the various stages of colorectal cancer tissues. RESULTS: The nested PCR results showed that the positive rate of JCPyV DNA increased with the progression of CRC stages. The archetypal-like, non-rearrangement genotype of JCPyV with subtle mutations was the major genotype found in CRC samples. CONCLUSIONS: This finding in our study suggests that there may be an association between JCPyV and CRC progression.

RNA Interference Approach Is a Good Strategy against SARS-CoV-2.

COVID-19, caused by SARS-CoV-2, created a devastating outbreak worldwide and consequently became a global health concern. However, no verifiable, specifically targeted treatment has been devised for COVID-19. Several emerging vaccines have been used, but protection has not been satisfactory. The complex genetic composition and high mutation frequency of SARS-CoV-2 have caused an uncertain vaccine response. Small interfering RNA (siRNA)-based therapy is an efficient strategy to control various infectious diseases employing post-transcriptional gene silencing through the silencing of target complementary mRNA. Here, we designed two highly effective shRNAs targeting the conserved region of RNA-dependent RNA polymerase (RdRP) and spike proteins capable of significant SARS-CoV-2 replication suppression. The efficacy of this approach suggested that the rapid development of an shRNA-based therapeutic strategy might prove to be highly effective in treating COVID-19. However, it needs further clinical trials.

Phosphorylation of Ser-80 of VP1 and Ser-254 of VP2 is essential for human BK virus propagation in tissue culture.

BK virus (BKV) infection may cause polyomavirus-associated nephropathy in patients with renal transplantation. Recently, the phosphorylated amino acids on the structural proteins VP1, VP2 and VP3 of BKV have been identified by liquid chromatography-tandem mass spectrometry in our laboratory. In this study, we further analysed the biological effects of these phosphorylation events. Phosphorylation of the BKV structural proteins was demonstrated by [(32)P]orthophosphate labelling in vivo. Site-directed mutagenesis was performed to replace all of the phosphorylated amino acids. The mutated BKV genomes were transfected into Vero cells for propagation analysis. The results showed that expression of the early protein LT and of the late protein VP1 by the mutants VP1-S80A, VP1-S80-133A, VP1-S80-327A, VP1-S80-133-327A and VP2-S254A was abolished. However, propagation of other mutants was similar to that of wild-type BKV. The results suggest that phosphorylation of Ser-80 of VP1 and Ser-254 of VP2 is crucial for BKV propagation.

The high incidence of JC virus infection in urothelial carcinoma tissue in Taiwan.

Human polyomaviruses, JC virus (JCV) and BK virus (BKV), usually remain latent in kidney and urothelial tissue after primary infection. Infection with human polyomavirus has still not been correlated conclusively with malignancy of kidney and urothelial tissue. The present study investigated further the possible relationship between JCV/BKV infection and urothelial carcinoma. Tissue samples were examined from 33 urothelial carcinomas and 5 renal cell carcinomas for JCV/BKV infection, using nested PCR with primers common to both JCV and BKV. The viral genotypes were further verified by endonuclease digestion and DNA sequencing following the PCR. In addition, immunohistochemistry and Western blotting were also performed to detect viral large tumor protein (LT) and the late capsid protein (VP1) in the tissue samples. The results from nested PCR showed that 90.1% (30/33) of the urothelial carcinomas samples and all of the renal cell carcinomas samples (5/5) were JCV DNA positive. Both archetypal and re-arranged JCV genotypes were detected. On the other hand, BKV DNA was detected in only one (3%) of the urothelial carcinoma tissue samples. The immunohistochemical results showed that 30% (10/33) of urothelial carcinoma tissues was stained positive for large tumor antigen (LT). However, the structural protein VP1 was not detectable in any of the tissue samples examined. The present study demonstrated that JCV is highly prevalent in urothelial carcinoma tissue as is the expression of large tumor antigen. Therefore, the findings support the hypothesis that JCV infection is associated with urothelial carcinoma.

Analysis of DNA methylation in human BK virus.

Human BK virus may cause nephropathy due to viral replication in patients who have undergone renal transplantation. However, the mechanism regulating replication of BKV is still not clear. Previous studies have suggested that epigenetic modifications may play a crucial role in virus replication. In this study, the DNA methylation profiles of five CpG sites located within the promoter/enhancer regions and nine CpG sites located within the early and late coding regions of the replicating BKV genome were investigated. BKV genomic DNA from mature virions and from the early and late phases of replicating BKV were examined for DNA methylation by bisulfite sequencing that covered 14 CpG sites. Our results showed that none of the examined BKV DNA from the various different stages of replication was methylated. This is the first report to analyze the methylation of BKV genomic DNA during viral replication. The results seem to indicate that methylation is not involved in regulation of BKV replication.

Flunarizine, a drug approved for treating migraine and vertigo, exhibits cytotoxicity in GBM cells.

Glioblastoma multiforme (GBM) is the most aggressive brain tumor with a poor prognosis. The current treatment regimen, including surgical resection, radiation, and temozolomide (TMZ) chemotherapy, is still not curative. Therefore, there is an emerging need to develop a drug to treat GBM or synergistic enhance TMZ effect on GBM cells. Flunarizine (FLN), a drug approved for treating migraine and vertigo, was analyzed for its cytotoxicity and synergistic effect with TMZ on GBM cells in this study. Cell proliferation, clonogenic assay, flow cytometry, and Western blotting were used to determine the effects of FLN on three GBM cells, U-87 MG, LN-229, and U-118 MG cells. We found that FLN induced GBM cell death. FLN also interfered with U-87 MG cell cycle progression. Flow cytometric analysis showed an increase of apoptotic cells after FLN treatment. Caspase 9, caspase 3, and Poly (ADP-ribose) polymerase (PARP) activation were involved in apoptosis induction in U-87 MG and LN-229, suggesting the possible involvement of an intrinsic apoptotic pathway. We found that FLN treatment inhibited Akt pathway activation in U-87 MG cells, and synergistically increased the cytotoxicity of three GBM cells when combined with TMZ treatment. In conclusion, our current data suggested that FLN inhibited cell viability by inducing apoptosis. FLN inhibited Akt activation and enhanced the sensitivity of GBM cells to TMZ. These findings may provide important information regarding the application of FLN in GBM treatment in the future.

Peptide-guided JC polyomavirus-like particles specifically target bladder cancer cells for gene therapy.

The ultimate goal of gene delivery vectors is to establish specific and effective treatments for human diseases. We previously demonstrated that human JC polyomavirus (JCPyV) virus-like particles (VLPs) can package and deliver exogenous DNA into susceptible cells for gene expression. For tissue-specific targeting in this study, JCPyV VLPs were conjugated with a specific peptide for bladder cancer (SPB) that specifically binds to bladder cancer cells. The suicide gene thymidine kinase was packaged and delivered by SPB-conjugated VLPs (VLP-SPBs). Expression of the suicide gene was detected only in human bladder cancer cells and not in lung cancer or neuroblastoma cells susceptible to JCPyV VLP infection in vitro and in vivo, demonstrating the target specificity of VLP-SPBs. The gene transduction efficiency of VLP-SPBs was approximately 100 times greater than that of VLPs without the conjugated peptide. JCPyV VLPs can be specifically guided to target particular cell types when tagged with a ligand molecule that binds to a cell surface marker, thereby improving gene therapy.

Flavopereirine Inhibits Hepatocellular Carcinoma Cell Growth by Inducing Cell-cycle Arrest, Apoptosis, and Autophagy-related Protein Expression.

BACKGROUND/AIM: Hepatocellular carcinoma (HCC) is the most common primary malignancy of the liver. Resistance to chemotherapy and side-effects remain a challenge for treating advanced and recurrent HCC. Therefore, there is an emerging need to develop new drugs to treat HCC. MATERIALS AND METHODS: We evaluated the anti-growth activity of flavopereirine in HepG2 and Huh7 HCC cell lines. Cell viability, cell-cycle profile, apoptosis, and autophagy-related protein expressions were analysed after flavopereirine treatment. RESULTS: Flavopereirine treatment induced G0/G1 cell-cycle arrest, with an increase of sub-G1 cells detected at the higher concentration and longer exposure to flavopereirine in HCC cells. Intrinsic and extrinsic pathways were involved in flavopereirine-induced apoptosis, as demonstrated by an increase of cleaved caspase 8 and 9 by western blotting. An alteration of autophagy-related protein expression was also found after flavopereirine treatment. CONCLUSION: Taken together, the current results indicate that flavopereirine exhibits good anticancer activity in HCC cells.

Piperlongumine induces autophagy in biliary cancer cells via reactive oxygen species-activated Erk signaling pathway.

Biliary cancer (BC) is an aggressive neoplasm with high mortality. BC can be categorized into three groups: Intrahepatic cholangiocarcinoma (CCA; also known as bile duct cancer), extrahepatic cholangiocarcinoma and gallbladder cancer. Due to its heterogeneity and aggressiveness, the response to current chemotherapy and radiotherapy methods in patients with BC is poor. Therefore, there is an urgent requirement to develop drugs to treat BC. Piperlongumine (PL), a naturally occurring small molecule isolated from Piper longum L., exhibits anticancer activity by inducing reactive oxygen species (ROS) production. In the present study, the effects of PL on cell proliferation, cell cycle, apoptosis and autophagy in BC cells were investigated. PL induced BC cell death in a concentration­ and time­dependent manner by inducing ROS production. PL induced cell cycle arrest in CCA cells (HuCCT­1) and gallbladder cancer cells (OCUG­1) cells, but with distinct cell cycle distribution profiles. PL caused G2/M cell cycle arrest in HuCCT­1 cells, and G0/G1 cell cycle arrest in OCUG­1 cells. PL induced apoptosis and autophagy; PL treatment induced accumulation of LC3­II in a concentration­ and time­dependent manner. The Erk signaling pathway appeared to be involved in autophagy induction. Application of the ROS scavenger, N­acetyl­l­cysteine, to BC cells attenuated the cell death, cell cycle arrest, apoptosis and autophagy induced by PL treatment. These findings indicated that PL may be a potential agent for BC treatment in the future.

Gene therapy for castration-resistant prostate cancer cells using JC polyomavirus-like particles packaged with a PSA promoter driven-suicide gene.

Prostate cancer is the second most common cancer in men globally. Prostate cancer patients at advanced stages are usually treated with androgen deprivation therapy (ADT). However, with disease progression, it often becomes the incurable castration-resistant prostate cancer (CRPC). JC polyomavirus (JCPyV) is a human DNA virus. Its virus-like particles (VLPs) exhibit similar tropism to native virions and they are capable of delivering exogenous genes to the target cells for expression. JCPyV has been detected in prostate cells; therefore, prostate cancer cells may be susceptible to JCPyV infection and JCPyV VLPs may be used as a vector for gene therapy against prostate cancer. Here we constructed a plasmid (pPSAtk) that allows expression of the thymidine kinase suicide gene only in androgen receptor (AR) positive prostate cancer cells using the prostate-specific antigen (PSA) promoter, and used JCPyV VLPs as a vector to carry pPSAtk (PSAtk-VLPs) for transcriptional targeting in prostate cancer cells. In this study, we found that PSAtk-VLPs could only kill AR-positive CRPC 22Rv1 cells in vitro and inhibit the growth of tumor nodules in the xenograft mouse model. Our results reveal that PSAtk-VLPs could potentially be used as a new option for treating CRPC patients in the future.

Gene therapy for human glioblastoma using neurotropic JC virus-like particles as a gene delivery vector.

Glioblastoma multiforme (GBM), the most common malignant brain tumor, has a short period of survival even with recent multimodality treatment. The neurotropic JC polyomavirus (JCPyV) infects glial cells and oligodendrocytes and causes fatal progressive multifocal leukoencephalopathy in patients with AIDS. In this study, a possible gene therapy strategy for GBM using JCPyV virus-like particles (VLPs) as a gene delivery vector was investigated. We found that JCPyV VLPs were able to deliver the GFP reporter gene into tumor cells (U87-MG) for expression. In an orthotopic xenograft model, nude mice implanted with U87 cells expressing the near-infrared fluorescent protein and then treated by intratumoral injection of JCPyV VLPs carrying the thymidine kinase suicide gene, combined with ganciclovir administration, exhibited significantly prolonged survival and less tumor fluorescence during the experiment compared with controls. Furthermore, JCPyV VLPs were able to protect and deliver a suicide gene to distal subcutaneously implanted U87 cells in nude mice via blood circulation and inhibit tumor growth. These findings show that metastatic brain tumors can be targeted by JCPyV VLPs carrying a therapeutic gene, thus demonstrating the potential of JCPyV VLPs to serve as a gene therapy vector for the far highly treatment-refractory GBM.