Tohoku J. Exp. Med., 2018 August, 245(4)

Treatment with Lactobacillus Retards the Tumor Growth of Head and Neck Squamous Cell Carcinoma Cells Inoculated in Mice

JUN MIYAGUCHI,¹ KIYOTO SHIGA,¹ KAZUMI OGAWA,² FUMIKO SUZUKI,³ KATSUNORI KATAGIRI,¹ DAISUKE SAITO,¹ AYA IKEDA,¹ AKIRA HORII,² MIKA WATANABE⁴ and SHIZUNOBU IGIMI⁵

¹Department of Head and Neck Surgery, Iwate Medical University, Morioka, Iwate, Japan
²Department of Molecular Pathology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
³Department of Otolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
⁴Division of Pathology, Tohoku University Hospital, Sendai, Miyagi, Japan
⁵Department of Agricultural Chemistry, Tokyo University of Agriculture, Tokyo, Japan

Bacteria have been used for more than a century to treat solid tumors. Because solid tumors generate an anaerobic environment, we evaluated the anti-tumor effect of the obligate anaerobe strain KK378, derived from Lactobacillus casei (L. casei), using mice bearing head and neck cancer. Wild-type L. casei is a nonpathogenic bacterium that is commonly used in foods. Moreover, patients with head and neck squamous cell carcinoma often have multiple cancers and cervical lymph node metastasis that can be directly sensed beneath the skin. To establish the animal model bearing head and neck cancer, we inoculated each of human squamous cell carcinoma cell lines, SAS, HSQ89, and HSC2, on the back skin of BALB/cSlc-nu/nu mice. After tumor formation, L. casei KK378 was administered directly into the tumor, and tumor size and serum cytokine levels were analyzed. Mice injected with 10⁸ cfu of L. casei KK378 showed reduction in tumor growth compared with PBS control; especially, the SAS tumor was significantly reduced (p = 0.008). Administered L. casei KK378 was detected in tumor tissues but not in normal tissues (liver, kidney, and lung) of SAS tumor-bearing mice, which was associated with increased blood cytokines (TNF-α, IFN-γ, IL-5, IL-10, and IL-12). Among these cytokines, the serum levels of IFN-γ and TNF-α were significantly increased (p < 0.05). In conclusion, L. casei KK378 infection may suppress tumor growth by inducing the host immune response. Direct injection of Lactobacillus into the tumor could be a potential strategy to treat head and neck squamous cell carcinoma.

keywords —— cytokine; head and neck squamous cell carcinoma; immuno-modulator; Lactobacillus casei; tumor suppression

© 2018 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2018, 245, 269-275

Correspondence: Kiyoto Shiga, M.D., Ph.D., Department of Head and Neck Surgery, Iwate Medical University, 19-1 Uchimaru, Morioka, Iwate 020-8505, Japan.

e-mail: kshiga@iwate-med.ac.jp