Current clinical success rates of adenoviral vector ( Adv ) -based gene therapy of squamous cell carcinoma ( SCC ) of the head and neck remain unsatisfactory. A major problem with this approach is thought to be related to low Adv transduction efficiency due to weak expression of the adenovirus receptor, coxsackie -adenovirus receptor ( CAR ), in SCC. To improve the limited infectivity of Adv in oral SCC, we constructed mutated Adv incorporating the integrin -binding motif, RGD, in the HI loop of the fiber knob. The mutated Adv infected target cells through integrins commonly expressed in oral SCC. LacZ marker gene expression after infection with this mutated Adv ( Adv -F / RGD ) in oral SCC cell lines that showed reduced expression of CAR was approximately 5 -10 times higher than that obtained with the parental Adv containing wild -type fiber knob ( Adv -F / wt ). In an in vitro study, transduction of oral cancer cell lines with Adv -F / RGD expressing human IL -2 ( AxCAhIL2 -F / RGD ) resulted in greater production of cytokine than AxCAhIL2 -F / wt infection. In an in vivo therapeutic xenograft model of oral SCC in nude mice, AxCAhIL2 -F / RGD demonstrated antitumor effects superior to those of AxCAhIL2 -F / wt. These data suggest that exploitation of genetically altered adenovirus vectors with integrin -binding motifs may offer significant improvements in oral SCC gene therapy.

Interferon-c (IFN-c) induced cell death in five oral squamous cell carcinoma (SCC) lines. Cell death was specific to IFN-c treatment and did not occur with either IFN-a or TNF-a. IFN-c did not induce typical apoptotic phenotype in cells , such as morphological changes and DNA ladder formation. Caspase-3 was partially activated by IFN-c. Protein levels of molecular chaperones were examined in cells treated with IFN-c. Among these, levels of heat shock protein 27 (Hsp27) were specifically reduced upon IFN-c treatment of oral SCC cells. Recombinant clones overexpressing Hsp27 were more resistant to IFN-c-induced cell death than parent cells. Conversely, cells expressing a dominant-negative mutant of Hsp27, in which three serine residues (15, 78 and 82) were replaced by glycine, were hypersensitive to the effects of IFNc and exhibited a typical apoptotic phenotype. Pretreatment of cells with IFN-c enhanced apoptotic cell death induced by cisplatin. Our data suggest that IFN-c suppresses Hsp27 expression in oral SCC cells and blocks the inhibitory effects of this molecular chaperone on apoptotic cell death. Moreover, IFN-c initiates the transition of oral SCC cells to the proapoptotic and/or aborted apoptotic state. Hsp27 plays a crucial role in the inhibition of apoptosis of oral SCC cells. Our findings highlight the importance of employing IFN-c in combination with certain anticancer drugs as treatments for oral cancer. We suggest that Hsp27 plays a significant role in the IFN-c-induced sensitization of oral SCC cells to anticancer drugs.

Cells of the human promonocytic cell line U937 were found to be sensitive to hexadeeylphosphocholine (HPC), which is a potential anticancer drug. Induction of apoptosis was found in U937 cells after treatment with HPC for 24 to 48 hr. The apoptosis in U937 cells exposed to HPC was increased significantly in the presence of interferon‐gamma (IFN‐γ). The augmentation of HPC‐induced apoptosis by IFN‐γ is repressed in cells (U937‐MP) persistently infected with mumps virus. A persistently infected cell line, U937‐MP, showed poor induction of signal transducers and activators of transcription‐1α (STAT‐1α), STAT‐2, p48 and IFN‐regulatory factor‐1 (IRF‐1), which are closely correlated with interferon‐α (IFN‐α) and IFN‐γ signaling pathways. Expression of MHC class‐I or class‐II was augmented by IFN‐α or IFN‐γ in U937 cells, but not in persistently infected cells. Therefore, it is suggested that the IFN‐γ signaling pathway plays an important role in the augmentation of HPC‐induced apoptosis. Mumps virus can suppress the IFN‐γ signaling pathway and subsequent development of apoptosis.

The cluster of genes encoding the botulinum progenitor toxin and the upstream region including p21 and p47 were divided into three different gene arrangements (class I-III). To determine the gene similarity of the type E neurotoxin (BoNT/E) complex to other types, the gene organization in the upstream region of the nontoxic-nonhemagglutinin gene (ntnh) was investigated in chromosomal DNA from Clostridium botulinum type E strain Iwanai and C. butyricum strain BL6340. The gene cluster of type E progenitor toxin (Iwanai and BL6340) was similar to those of type F and type A (from infant botulism in Japan), but not to those of types A, B, and C. Though genes for the hemagglutinin component and P21 were not discovered, genes encoding P47, NTNH, and BoNT were found in type E strain Iwanai and C. butyricum strain BL6340. However, the genes of ORF-X1 (435 bp) and ORF-X2 (partially sequenced) were present just upstream of that of P47. The orientation of these genes was in inverted direction to that of p47. The gene cluster of type E progenitor toxin (Iwanai and BL6340) is, therefore, a specific arrangement (class IV) among the genes encoding components of the BoNT complex.

Verotoxin type 2 (VT2) produced by enterohemorrhagic Escherichia coli (EHEC) has been shown to have high cytotoxic potency toward several human B lymphoid cell lines with and without Epstein-Barr virus (EBV). Cell death, apoptosis induced by VT2, is closely correlated with the expression of receptor molecule Gb3/CD77, recognized by the toxin, but not with the infection or presence of EBV. Pretreatment of cells with interferon-alpha (IFN-alpha) for 24 h resulted in augmentation of apoptosis by VT2. Pretreatment within 8 h, however, was not effective. It has been reported that IFN-alpha-induced apoptosis is correlated with the induction of the 2',5'-OAS/RNase L system or dsRNA-activated protein kinase (PKR) or both. We have established persistent infection in both Akata and P3HR-1 cells with mumps virus. The persistently infected cell lines, P3HR-MP2 and Akata-MP2, showed poor induction of 2',5'-OAS and PKR in response to IFN-alpha. Augmentation of VT2-induced apoptosis by IFN-alpha was not found in the cell lines P3HR-MP2 and Akata-MP2. Therefore, these findings were interpreted to indicate that augmentation of VT2-induced apoptosis by IFN-alpha may be mediated by PKR and the 2',5'-OAS/RNaseL system. It is also suggested that mumps virus can suppress apoptosis and establish persistent infection.