Adenovirus type 5 E1A has been implicated in mediation of tumor suppression. Preclinical gene therapy studies have additionally shown that complete growth suppression can be achieved by incomplete transfer of E1A into tumors, suggesting that a bystander effect may also be associated with E1A. In this study, we investigated the E1A-mediated bystander effect and the mechanisms that may be associa...

In this work, we studied alpha-particle induced and medium-mediated bystander effects in Chinese hamster ovary (CHO) cells through micronucleus (MN) assay. We showed that signal transduction from irradiated cells to bystander cells occur within a short time after irradiation. We then studied the effects of ROS (reactive oxygen species)-scavenging catechins in the medium before irradiation. We o...

The radiation-induced bystander effect is defined as "the induction of biological effects in cells that are not directly traversed by a charged particle but are in close proximity to cells that are." Although these bystander effects have been demonstrated with a variety of biological endpoints in both human and rodent cell lines (as well as in 3D tissue samples), the mechanism of the phenomenon...

In our previous study we evaluated the antitumor effect of herpes simplex virus-thymidine kinase gene (HSV-tk) on human medulloblastomas (MBs) in a therapeutic delivery system using the immortalized neural stem cell (NSC) line C17.2. However, our findings indicated that the bystander effect between C17.2tk and Daoy MB cells was weak compared to the bystander effect between NSCtk and C6 glioma c...

OBJECTIVE Although socioeconomic status (SES) has been linked to multiple health outcomes, there have been few studies of the effect of SES on the provision of bystander cardiopulmonary resuscitation (CPR) during cardiac arrest events and no studies that we know of on the effect of SES on the provision of dispatcher-assisted bystander CPR. This study sought to define the relationship between SE...

OBJECTIVE The objective of our study was to explore a possible molecular mechanism by which ultraviolet (UV) biophotons could elicit bystander responses in reporter cells and resolve the problem of seemingly mutually exclusive mechanisms of a physical UV signal & a soluble factor-mediated bystander signal. METHODS The human colon carcinoma cell line, HCT116 p53 +/+, was directly irradiated wi...

Herpes simplex virus thymidine kinase (HSV-tk)/ganciclovir (GCV) viral-directed enzyme prodrug gene therapy causes potent, tumor-selective cytotoxicity in animal models in which HSV-tk gene transduction is limited to a minority of tumor cells. The passage of toxic molecules from HSV-tk+ cells to neighboring HSV-tk- cells during GCV therapy is one mechanism that may account for this "bystander" ...

The controversial use of a linear, no threshold extrapolation model for low dose risk assessment has become even more so in light of the recent reports on the bystander phenomenon. The answer to the question as to which of the two phenomena, bystander versus adaptive response, is more important has practical implication in terms of low dose radiation risk assessment. In this review, genotoxicit...

Chloroethylnitrosourea (CENU) chemotherapy is used for the treatment of melanoma tumors. The main mechanism of action of this anticancer agent is via DNA damage. We recently showed in murine experiments using a parental double B16 melanoma tumor model that, after treatment of primary tumors with cystemustine (CENU agent), untreated secondary tumors exhibited growth inhibition and metabolism dis...