Mesenchymal stem cells (MSCs) were adenovirally engineered to secrete interleukin-12 (AdIL-12-MSCs) and evaluated for their anticarcinogenesis efficacy against three kinds of unestablished tumor models including B16 melanoma, LLC Lewis lung cancer and HCC hepatoma. Injection of AdIL-12-MSCs into protected mice before tumor inoculation prevented all of 12 mice in B16 preventive groups, 10 out of 12 in LLC lung cancer model and 11 out of 12 mice in HCC hepatoma model from developing tumors, whereas the control groups pre-receiving PBS were validated for 100% carcinogenesis; the tumor formation rates in free-AdIL-12 and vacant MSC groups were unveiled between approximately 83 and 100% even with plentiful angiogenesis and newborn lymphatic vessels, as well as distant metastases. As a novel approach, AdIL-12-MSC has revealed expected preventive effects on carcinogenesis (P<0.01) with low-toxic, broad-spectrum and long-range superiorities. In conclusion, our data indicate that AdIL-12-MSC possess the potential for tropism to preclinical tumor lesions and deprives surviving or hibernating tumor cells, which have escaped from conventional treatments, of revival and recurrence.

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Opioid receptors can couple to K(+) and Ca(2+) channels, adenylyl cyclase, and phosphatidyl inositol turnover. Any of these actions may be important in the regulation of neurotransmitter and hormone release from excitable cells. GH(3) cells exhibit spontaneous oscillations of intracellular Ca(2+) concentration ([Ca(2+)](i)) and prolactin release. Activation of cloned delta-opioid receptors stably expressed in GH(3) cells inhibits both spontaneous Ca(2+) signaling and basal prolactin release. The objective of this study was to examine a possible role for K(+) channels in these processes using the patch-clamp technique, fluorescence imaging, and a sensitive ELISA for prolactin. The selective delta receptor agonist [D-Pen(2), D-Pen(2)]enkephalin (DPDPE) inhibited [Ca(2+)](i) oscillations in GH(3) cells expressing both mu and delta receptors (GH(3)MORDOR cells) but had no effect on control GH(3) cells or cells expressing mu receptors alone (GH(3)MOR cells). The inhibition of [Ca(2+)](i) oscillations by DPDPE was unaffected by thapsigargin pretreatment, suggesting that this effect is independent of inositol 1,4,5-triphosphate-sensitive Ca(2+) stores. DPDPE caused a concentration-dependent inhibition of prolactin release from GH(3)MORDOR cells with an IC(50) of 4 nM. DPDPE increased inward K(+) current recorded from GH(3)MORDOR cells but had no significant effect on K(+) currents recorded from control GH(3) cells or GH(3)MOR cells. The mu receptor agonist morphine also had no effect on currents recorded from control cells but activated inward K(+) currents recorded from GH(3)MOR and GH(3)MORDOR cells. Somatostatin activated inward currents recorded from all three cell lines. The DPDPE-sensitive K(+) current was inwardly rectifying and was inhibited by Ba(2+) but not TEA. DPDPE had no effect on delayed rectifier-, Ca(2+)-, and voltage-activated or A-type K(+) currents, recorded from GH(3)MORDOR cells. Ba(2+) attenuated the inhibition of [Ca(2+)](i) and prolactin release by DPDPE, whereas TEA had no effect, consistent with an involvement of K(IR) channels in these actions of the opioid.