Fig. 4

Increased anti-tumor efficacy of chemotherapy in the presence of B. ovatus and B. xylanisolvens.a Experimental design: male 6-week C57BL6/N mice (n = 5–8) were treated with antibiotic cocktail in drinking water for 1 week before bacterial oral gavage. Control PBS, B. ovatus and B. xylanisolvens, and C. symbiosum and R. gnavus were orally gavaged into mice 1 week prior to tumor cell inoculation. A total of 10⁷ Lewis lung cancer cells in 200 μl PBS were subcutaneously injected into the mice to induce tumor formation. Mice were treated with erlotinib (60 mg/kg body weight) once the tumor size reached approximately 250–500 mm³. Time in days is relative to tumor cells injection. b Tumor size measurement at day 14. c Tumor growth curve after Lewis lung carcinoma cell inoculation. Dark dots indicate the application of erlotinib. d, e CRL5883 bronchoalveolar carcinoma cell line was cultured for 72 h in the presence of erlotinib (d) or drug-free (e) supernatants from R (B. xylanisolvens and B. ovatus) or NR (R. gnavus and C. symbiosum) bacteria species. d Non-linear regression curves showing cell viability as percentage of cell control viability. Bacterial supernatants had n = 4, GAM control had n = 2, and cell control had n = 10. e Cell viability is presented as percentage of cell control viability. Colored circles show individual data points. Outliers were identified and removed by the ROUT method (Q = 0.1%). Supernatants had n = 3–4 and cell control had n = 16. All data are mean ± SEM. Significant differences were identified via unpaired t test (*p < 0.05, **p < 0.005). f, g Tumor expressions of chemokines involved in the recruitment of T cells (f), myeloid cells, and cytotoxic T cells (g) by real-time PCR (normalized against GAPDH). Data are presented as mean ± SEM. *p < 0.05, **p < 0.01, ***p < 0.001