Immunoprotection against murine bladder carcinoma by octaarginine-modified liposomes incorporating cell wall of Mycobacterium bovis bacillus Calmette-Guérin

Authors

  • Akira Joraku,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Atthachai Homhuan,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Koji Kawai,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Takahiro Yamamoto,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Jun Miyazaki,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Kentaro Kogure,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Ikuya Yano,

    1. Japan BCG Central Laboratory, Kiyose, Tokyo, Japan
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  • Hideyoshi Harashima,

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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  • Hideyuki Akaza

    1. Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, Tsukuba, Ibaraki, Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo, Hokkaido, and
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Akira Joraku, Graduate School of Comprehensive Human Sciences, Department of Urology, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8575, Japan.
e-mail: ajoraku@md.tsukuba.ac.jp

Abstract

OBJECTIVE

To develop a prototype of a non-live bacterial agent that consists of a cell wall (CW) preparation from heat-killed bacillus Calmette-Guérin (BCG-CW) incorporated into octaarginine-modified cationized liposomes as a vector (R8-liposome-BCG-CW), and to evaluate its immunoprotective potentiation in mice, as although BCG is an established effective immunotherapy for nonmuscle-invasive bladder cancer, more active and less toxic treatments are needed.

MATERIALS AND METHODS

The cellular interaction of R8-liposome-BCG-CW co-cultured with mouse bladder cancer cell line (MBT-2) was examined by confocal laser scanning microscopy. MBT-2 cells (7 × 105) were subcutaneously inoculated with 1 mg BCG, 0.1 mg or 1 mg BCG-CW, 0.1 mg or 1 mg R8-liposome-BCG-CW in female C3H/HeN mice. The MBT-2 cells pretreated with BCG or R8-liposome-BCG-CW were re-challenged at 6 weeks. The sizes of the primary and re-challenged tumours were evaluated at 4 and 10 weeks, respectively.

RESULTS

Confocal laser scanning microscopy showed the enhanced incorporation of R8-liposome-BCG-CW into MBT-2 cells after 1 h of co-incubation. 0.1 mg R8-liposome-BCG-CW completely inhibited the growth of MBT-2 tumours while 0.1 mg BCG-CW alone did not (P = 0.002). Mice vaccinated with a mixture of MBT-2 cells and R8-liposome-BCG-CW inhibited the growth of re-challenged tumour of MBT-2 cells pretreated with BCG or R8-liposome-BCG-CW but did not inhibit that of MBT-2 cells with no pretreatment at 10 weeks, with mean (sd) tumours sizes of 54 (60) mm2 (P < 0.001) or 69 (43) mm2 (P = 0.003) compared with 309 (125) mm2, respectively.

CONCLUSION

The immunotherapeutic potential of BCG-CW was enhanced by improving cellular association using the R8-liposomes delivery system. Development of this non-live bacterial agent may contribute to providing a more active and less toxic tool as a substitute for live BCG as immunotherapy against nonmuscle-invasive bladder cancer in the future.

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