Isolated limb perfusion: a novel delivery system for wild-type p53 and fiber-modified oncolytic adenoviruses to extremity sarcoma

Recognition, Staging, and Management of Melanoma

Melanoma accounts for approximately 1% of all skin cancers but contributes to almost all skin cancer deaths. The developing picture suggests that melanoma phenotypes are driven by epigenetic mechanisms that reflect a complex interplay between genotype and environment. Furthermore, the growing consensus is that current classification standards, notwithstanding pertinent clinical history and appropriate biopsy, fall short of capturing the vast complexity of the disease. This article summarizes the current understanding of the clinical picture of melanoma, with a focus on the tremendous breakthroughs in molecular classification and therapeutics.

Tumor necrosis factor-mediated downregulation of spinal astrocytic connexin43 leads to increased glutamatergic neurotransmission and neuropathic pain in mice

Spinal cord astrocytes are critical in the maintenance of neuropathic pain. Connexin 43 (Cx43) expressed on spinal dorsal horn astrocytes modulates synaptic neurotransmission, but its role in nociceptive transduction has yet to be fully elaborated. In mice, Cx43 is mainly expressed in astrocytes, not neurons or microglia, in the spinal dorsal horn. Hind paw mechanical hypersensitivity was observed beginning 3days after partial sciatic nerve ligation (PSNL), but a persistent downregulation of astrocytic Cx43 in ipsilateral lumbar spinal dorsal horn was not observed until 7days post-PSNL, suggesting that Cx43 downregulation mediates the maintenance and not the initiation of nerve injury-induced hypersensitivity. Downregulation of Cx43 expression by intrathecal treatment with Cx43 siRNA also induced mechanical hypersensitivity. Conversely, restoring Cx43 by an adenovirus vector expressing Cx43 (Ad-Cx43) ameliorated PSNL-induced mechanical hypersensitivity. The sensitized state following PSNL is likely maintained by dysfunctional glutamatergic neurotransmission, as Cx43 siRNA-induced mechanical hypersensitivity was attenuated with intrathecal treatment of glutamate receptor antagonists MK801 and CNQX, but not neurokinin-1 receptor antagonist CP96345 or the Ca(2+) channel subunit α2δ1 blocker gabapentin. The source of this dysfunctional glutamatergic neurotransmission is likely decreased clearance of glutamate from the synapse rather than increased glutamate release into the synapse. Astrocytic expression of glutamate transporter GLT-1, but not GLAST, and activity of glutamate transport were markedly decreased in mice intrathecally injected with Cx43-targeting siRNA but not non-targeting siRNA. Glutamate release from spinal synaptosomes prepared from mice treated with either Cx43-targeting siRNA or non-targeting siRNA was unchanged. Intrathecal injection of Ad-Cx43 in PSNL mice restored astrocytic GLT-1 expression. The cytokine tumor necrosis factor (TNF) has been implicated in the induction of central sensitization, particularly through its actions on astrocytes, in the spinal cord following peripheral injury. Intrathecal injection of TNF in naïve mice induced the downregulation of both Cx43 and GLT-1 in spinal dorsal horn, as well as hind paw mechanical hypersensitivity, as observed in PSNL mice. Conversely, intrathecal treatment of PSNL mice with the TNF inhibitor etanercept prevented not only mechanical hypersensitivity but also the downregulation of Cx43 and GLT-1 expression in astrocytes. The current findings indicate that spinal astrocytic Cx43 are essential for the maintenance of neuropathic pain following peripheral nerve injury and suggest modulation of Cx43 as a novel target for developing analgesics for neuropathic pain.

Progress of oncolytic viruses in sarcomas

Oncolytic virotherapy has shown exciting promise for the treatment of many types of solid tumors. Pediatric sarcomas are an aggressive type of pediatric malignancy known to show limited responsiveness to current therapies, leading to unacceptably high morbidity and mortality. Oncolytic viruses have only recently been used for the treatment of this challenging cancer, and results have been encouraging. Five clinical trials are currently open evaluating the use of oncolytic viruses in pediatric malignancies. Advances in genetic engineering of the viruses include improving the ability of the virus to infect tumor cells, engineering the virus with transgenes which improve the virus' ability to kill tumor cells and manipulating the virus to enhance concomitantly administered therapies. Further understanding of the antiviral immune response and a viral induced anti-tumor immune response will permit a maximization of oncolytic virotherapy.

Oncolytic vesicular stomatitis virus administered by isolated limb perfusion suppresses osteosarcoma growth

A significant limitation to oncolytic virotherapy in vivo is the lack of a clinically relevant means of delivering the virus. We evaluated the oncolytic activity of vesicular stomatitis virus (VSV) in human osteosarcoma cells and explored isolated limb perfusion (ILP) as a novel oncolytic virus delivery system to extremity sarcoma in immune-competent rats. Human and rat osteosarcoma cells transduced with rVSV-lacZ uniformly expressed β-gal. VSV was fully capable of replicating its RNA genome in all osteosarcoma cell lines, and efficiently killed them in time- and dose-dependent manners, whereas normal bone marrow stromal cells were refractory to the virus. VSV delivered by ILP inhibited growth of osteosarcoma xenografts more potently than that injected intravenously and intratumorally in the hind limb of immune-competent rats. Histopathological sections of tumor lesions treated by ILP-delivered VSV showed positive for VSV-G protein. There were no VSV-G expressions in perfused leg muscle, nonperfused leg muscle, brain, lung, and liver in VSV-treated rats. Our findings show efficient VSV gene expression and replication in osteosarcoma cells, suggesting that osteosarcoma may be a promising target for oncolytic virotherapy with VSV. Furthermore, we firstly showed that ILP of VSV against extremity sarcoma caused antitumor activity.

Adenovirus-mediated expression of truncated E2F-1 suppresses tumor growth in vitro and in vivo

BACKGROUND

Adenovirus (Ad)-mediated E2F-1 gene transfer induces apoptosis in cancer cells in vitro and in vivo, but clinical application of E2F-1 in cancer gene therapy remains controversial because of the oncogenic potential of E2F-1. This barrier can be circumvented by using the truncated form of the E2F-1 gene (E2Ftr) (amino acids 1 through 375), which lacks the E2F-1 transactivation domain and cell cycle-promoting effects.

METHODS

The authors constructed 3 adenoviral vectors that expressed E2Ftr under regulation of the tetracycline (Tet)-off system (AdTet-E2Ftr1, AdTet-E2Ftr2, and AdTet-E2Ftr3). These vectors were compared for E2Ftr expression and apoptosis induction in cancer cells and normal cells. E2Ftr antitumor activity in vivo also was assessed in a melanoma xenograft model.

RESULTS

One of the 3 vectors, AdTet-E2Ftr3, had the highest E2Ftr protein expression levels, which were correlated with the greatest induction of apoptosis and inhibition of cancer cell growth. E2Ftr induced apoptosis in a variety of cancer cell lines independent of p53 status with little cytotoxicity in normal cell lines. In a mouse melanoma xenograft model, AdTet-E2Ftr3 exhibited an approximately 80% decrease in tumor size compared with controls in vivo.

CONCLUSIONS

The current results indicated that AdTet-E2Ftr3 is a novel anticancer agent that has significant therapeutic activity in vitro and in vivo.

Locoregional intravascular viral therapy of cancer: precision guidance for Paris's arrow?

Viral therapy of cancer includes strategies such as viral transduction of tumour cells with 'suicide genes', using viral infection to trigger immune-mediated tumour cell death and using oncolytic viruses for their direct anti-tumour action. However, problems still remain in terms of adequate viral delivery to tumours. A role is also emerging for single-organ isolation and perfusion. Having begun with the advent of isolated limb perfusion for extremity malignancy, experimental systems have been developed for the perfusion of other organs, particularly the liver, kidneys and lungs. These are beginning to be adopted into clinical treatment pathways. The combination of these two modalities is potentially significant. Locoregional perfusion increases the exposure of tumour cells to viral agents. In addition, the avoidance of systemic elimination through the immune and reticulo-endothelial systems should provide a mechanism for increased transduction/infection of target cells. The translation of laboratory research to clinical practice would occur within the context of perfusion programmes, which are already established in the clinic. Many of these programmes include the use of vasoactive cytokines such as tumour necrosis factor-alpha, which may have an effect on viral uptake. Evidence of activation of specific anti-tumour immunological responses by intratumoural and other existing methods of viral administration raises the intriguing possibility of a locoregional therapy, with the ability to affect distant sites of disease. In this review, we examined the state of the literature in this area and summarized current findings before indicating likely areas of continuing interest.

14-3-3 zeta down-regulates p53 in mammary epithelial cells and confers luminal filling

Recent progress in diagnostic tools allows many breast cancers to be detected at an early preinvasive stage. Thus, a better understanding of the molecular basis of early breast cancer progression is essential. Previously, we discovered that 14-3-3 zeta is overexpressed in >40% of advanced breast cancers, and this overexpression predicts poor patient survival. Here, we examined at what stage of breast disease 14-3-3 zeta overexpression occurs, and we found that increased expression of 14-3-3 zeta begins at atypical ductal hyperplasia, an early stage of breast disease. To determine whether 14-3-3 zeta overexpression is a decisive early event in breast cancer, we overexpressed 14-3-3 zeta in MCF10A cells and examined its effect in a three-dimensional culture model. We discovered that 14-3-3 zeta overexpression severely disrupted the acini architecture resulting in luminal filling. Proper lumen formation is a result of anoikis, apoptosis due to detachment from the basement membrane. We found that 14-3-3 zeta overexpression conferred resistance to anoikis. Additionally, 14-3-3 zeta overexpression in MCF10A cells and in mammary epithelial cells (MEC) from 14-3-3 zeta transgenic mice reduced expression of p53, which is known to mediate anoikis. Mechanistically, 14-3-3 zeta induced hyperactivation of the phosphoinositide 3-kinase/Akt pathway which led to phosphorylation and translocation of the MDM2 E3 ligase resulting in increased p53 degradation. Ectopic expression of p53 restored luminal apoptosis in 14-3-3 zeta-overexpressing MCF10A acini in three-dimensional cultures. These data suggest that 14-3-3 zeta overexpression is a critical event in early breast disease, and down-regulation of p53 is one of the mechanisms by which 14-3-3 zeta alters MEC acini structure and increases the risk of breast cancer.

A preclinical model for predicting drug response in soft-tissue sarcoma with targeted AAVP molecular imaging

Human sarcomas are rare but diverse malignant tumors derived from mesenchymal tissue. Clinical response to therapy is currently determined by the modified World Health Organization (WHO) criteria or the Response Evaluation Criteria in Solid Tumors (RECIST), but these standards correlate poorly with sarcoma patient outcome. We introduced ligand-directed particles with elements of AAV and phage (AAVP) to enable integration of tumor targeting to molecular imaging. We report drug-response monitoring and prediction in a nude rat model of human sarcoma by AAVP imaging. As a proof-of-concept, we imaged Herpes simplex thymidine kinase in a clinic-ready setting with PET to show that one can a priori predict tumor response to a systemic cytotoxic. Given the target expression in patient-derived sarcomas, this platform may be translated in clinical applications. Sarcoma-specific ligands and promoters may ultimately lead to an imaging transcriptome.