Effects of Antibacterial Agents on Cancerous Cell Proliferation.

Myelosuppression, a side effect of anticancer drugs, makes people more susceptible to infectious diseases by compromising the immune system. When a cancer patient develops a contagious disease, treatment with an anticancer drug is suspended or postponed to treat the infectious disease. If there was a drug that suppresses the growth of cancer cells among antibacterial agents, it would be possible to treat both infectious diseases and cancer. Therefore, this study investigated the effect of antibacterial agents on cancer cell development. Vancomycin (VAN) had little effect on cell proliferation against the breast cancer cell, MCF-7, prostate cancer cell, PC-3, and gallbladder cancer cell, NOZ C-1. Alternatively, Teicoplanin (TEIC) and Daptomycin (DAP) promoted the growth of some cancer cells. In contrast, Linezolid (LZD) suppressed the proliferation of MCF-7, PC-3, and NOZ C-1 cells. Therefore, we found a drug that affects the growth of cancer cells among antibacterial agents. Next, when we examined the effects of the combined use of existing anticancer and antibacterial agents, we found VAN did not affect the growth suppression by anticancer agents. However, TEIC and DAP attenuated the growth suppression of anticancer agents. In contrast, LZD additively enhanced the growth suppression by Docetaxel in PC-3 cells. Furthermore, we showed that LZD inhibits cancer cell growth by mechanisms that involve phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway suppression. Therefore, LZD might simultaneously treat cancer and infectious diseases.

Increased Vancomycin Clearance in Patients with Solid Malignancies.

Vancomycin (VAN) is an anti-microbial agent used to treat a number of bacterial infections, which has a high incidence of nephrotoxicity. We examined the pharmacokinetics of VAN retrospectively based on trough concentrations at large scale and identified pharmacokinetic differences between Japanese patients having solid malignancy and non-malignancy patients. Data were analyzed from 162 solid malignancy patients and 261 non-malignancy patients, including the patient's background, VAN dose, and pharmacokinetics of VAN. We failed to detect differences in values for VAN clearance or shorter elimination half-lives between these two groups. In contrast, multiple regression analysis under adjusting for confounding factors by propensity score, showed that VAN clearance significantly increased in relation to solid malignancies in each stage. We conclude that VAN clearance in solid malignancy patients is increased and that the blood concentration of VAN becomes lower than expected. These results suggest that early monitoring of VAN levels in solid malignancy patients might be essential for maintaining desired effects without side-effects.

Augmented Renal Clearance of Vancomycin in Hematologic Malignancy Patients.

The pharmacokinetics of vancomycin (VAN) was retrospectively examined based on trough concentrations at large scale to identify pharmacokinetic differences between Japanese hematologic malignancy and non-malignancy patients. Data from 261 hematologic malignancy patients and 261 non-malignancy patients, including the patient's background, VAN dose, and pharmacokinetics of VAN estimated by an empirical Bayesian method, were collected and analyzed. Our results showed significantly higher values for VAN clearance and shorter elimination half-lives in patients with hematologic malignancies than non-malignancy patients. In addition, multiple regression analysis under adjusting for confounding factors by propensity score, showed that VAN clearance significantly increased in relation to hematologic malignancies. In conclusion, since in hematologic cancer patients VAN clearance is increased, the blood concentration of VAN becomes lower than expected and this may contribute to the survival of resistant bacteria when VAN is administered at low doses. These results suggest that early monitoring of VAN levels in hematologic cancer patients might be recommended to maintain desired effects without side-effects.

Cell line-dependent internalization pathways determine DNA transfection efficiency of decaarginine-PEG-lipid.

Previously, we have reported that decaarginine-conjugated PEG-lipids (R10B) efficiently delivered plasmid DNA (pDNA) into human cervical carcinoma HeLa cells via macropinocytosis; however, the mechanism of cellular uptake by R10B was not evaluated in other cell lines. In this study, we investigated the internalization mechanism by R10B/pDNA complex (R10B-lipoplex) in human prostate tumor PC-3 and human nasopharyngeal tumor KB cells, and compared with that in HeLa cells. Although it was necessary for R10B-lipoplex to associate with heparan sulfate (HS) on the cell surface in all cell lines, the R10B-lipoplex was internalized primarily through clathrin-mediated endocytosis in PC-3 and KB cells, and macropinosytosis in HeLa cells. In HeLa cells, treatment with the R10B-lipoplex induced the formation of lamellipodia for macropinocytosis, but did not in KB and PC-3 cells. Furthermore, the highest transfection efficiency by R10B-lipoplex was observed in HeLa cells. These findings indicated that the R10B-lipoplex induced the formation of lamellipodia in HeLa cells after binding to HS on the cells and was then internalized by macropinocytosis, which could induce high gene expression because of escaping degradation in lysosomes. Cell physiology might be a critical factor in cellular internalization and efficient transfection by cell penetration peptide.

The distribution of mRNA expression and protein after hydrodynamic injection of transgene in mice.

The hydrodynamic method by rapid intravenous injection of a large volume of plasmid DNA is known to be an efficient and liver-specific method of in vivo gene delivery and achieves high levels of foreign gene expression, particularly in hepatocytes. Low transgene activities have also been observed in other organs such as the spleen and lung; however, the expression profiles of mRNA and protein are still unknown. Therefore, we investigated the localization of luciferase mRNA by in situ hybridization and luciferase activity in mice after transfection of pCMV-luc encoding the luciferase gene under the control of cytomegalo virus (CMV) promoter. We found that hydrodynamic injection effectively induced mRNA expression of the transgene only in the liver although transgene activities were observed in other organs. The transgene activity observed in other organs may be due to leakage from hepatocyte gene expression by transient increase in the permeability of the hepatocyte cellular membrane caused by increased pressure by hydrodynamic injection.

Non-ionic surfactant modified cationic liposomes mediated gene transfection in vitro and in the mouse lung.

As reported previously, cationic liposomes formulated with dioleoylphosphatidylethanolamine (DOPE) and N,N-methyl hydroxyethyl aminopropane carbamoyl cholesterol (MHAPC-liposomes) achieved efficient gene transfection in the mouse lung following intratracheal injection. We have studied here the role of surfactants, mannosylerythritol lipid-A (MEL-A) and polysorbate 80 (Tween 80), in affecting gene transfection of MHAPC-lipoplexes (complex with pCMV-luc DNA) in A549 cells and in the mouse lung. MEL-A increased gene transfection of MHAPC-lipoplexes significantly in vitro and slightly in the mouse lung, while Tween 80 decreased it both in vitro and in vivo. As assessed by confocal laser scanning microscopy and fluorescence imaging, MEL-A might faciliate gene dissociation from MHAPC-lipoplexes with fluorescein-labeled oligodeoxynucleotide (FITC-ODN) after internalization into the cells and retained the lipoplexes in the mouse lung for prolonged time, while Tween 80 was inefficient to deliver foreign gene into target cells and in the lung. These results demonstrated that MEL-A is advantageous to Tween 80 in the modification of cationic liposomes as gene delivery vectors in the lung.

Decaarginine-PEG-liposome enhanced transfection efficiency and function of arginine length and PEG.

Oligoarginine-conjugated lipids ((Arg)n-PEG-lipid) (n=4, 6, 8, and 10: number of arginine residues) are novel gene delivery vectors. We prepared two oligoarginine-modified liposomes using (Arg)n-lipid without and with poly(ethylene glycol) (PEG) spacer ((Arg)n-L and (Arg)n-PEG-L), and investigated the effect of PEG spacer and oligoarginine length of liposomes on cellular uptake, gene transfection, and its mechanism in HeLa cells, using complexes with plasmid DNA (DNA) or oligodeoxynucleotide. Transfection efficiency increased as the number of arginine residues increased and Arg10-PEG-L/DNA complexes (lipoplexes) showed the highest gene transfection efficiency among (Arg)n- and (Arg)n-PEG-lipoplexes. Arg4- and Arg4-PEG-lipoplexes were taken up greatly into cells, but showed lower transfection efficiency than Arg10- and Arg10-PEG-lipoplexes, respectively. The different gene expression by Arg4-L to Arg10-L with or without PEG spacer may be explained by the different intracellular uptake mechanism. The main cellular uptake mechanism of Arg10-L and Arg10-PEG-L was the macropinocytosis pathway, whereas that of Arg4-L and Arg4-PEG-L was not. PEG spacer was more effective for intracellular trafficking than Arg length and surface charge of lipoplex which depends on Arg length at the almost same size of lipoplexes. The findings suggested that Arg10-PEG-L was a superior vector since Arg10 induced the macropinocytosis uptake pathway.