Local bacteria affect the efficacy of chemotherapeutic drugs - PubMed (original) (raw)

Local bacteria affect the efficacy of chemotherapeutic drugs

Panos Lehouritis et al. Sci Rep. 2015.

Abstract

In this study, the potential effects of bacteria on the efficacy of frequently used chemotherapies was examined. Bacteria and cancer cell lines were examined in vitro and in vivo for changes in the efficacy of cancer cell killing mediated by chemotherapeutic agents. Of 30 drugs examined in vitro, the efficacy of 10 was found to be significantly inhibited by certain bacteria, while the same bacteria improved the efficacy of six others. HPLC and mass spectrometry analyses of sample drugs (gemcitabine, fludarabine, cladribine, CB1954) demonstrated modification of drug chemical structure. The chemoresistance or increased cytotoxicity observed in vitro with sample drugs (gemcitabine and CB1954) was replicated in in vivo murine subcutaneous tumour models. These findings suggest that bacterial presence in the body due to systemic or local infection may influence tumour responses or off-target toxicity during chemotherapy.

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Figures

Figure 1

Figure 1. Tumour Cell Survival.

Cell survival assay. (a) E.coli at different cfu/ml were co-incubated with AQ4N (10 μM) after which the supernatant was applied directly to LLC cells (P < 0.01). (b) E. coli at different cfu/ml were co-incubated with gemcitabine (10 μM) after which the supernatant was directly applied to 4T1 Luc cells (P < 0.01). E.coli was co-incubated with Tegafur (c) or CB1954 (d) at the indicated concentrations after which the supernatant was directly applied to TRAMPC1 cells or CT26 (P < 0.01). Data (a–f) represent the average and standard error of four technical replicates. Data shown are representative of 3 independent experiments. (e) Tumour cell survival assay stained with MTS. Gemcitabine (10 μM) was incubated with live or heat killed E. coli (P < 0.001). (f) Tumour cell survival assay. Gemcitabine (10 μM) was incubated with either bacterial lysate (equivalent amounts to cell survival assay live bacteria dosages) alone or bacterial lysate that has been heat inactivated (P < 0.001). Data represent the average and standard error of four technical replicates. Data shown are representative of 2 independent experiments.

Figure 2

Figure 2. HPLC analysis of drug biotransformations.

Chromatograms: (a) Top; Vehicle alone (PBS DMSO 0.1%), Bottom; E. coli alone (b) Top; Gemcitabine, Bottom; Gemcitabine and E. coli. (c) Top; Fludarabine, Bottom; Fludarabine and E. coli (d) Top; Cladribine, Bottom; E. coli and Fludarabine. (e) Top; CB1954, Bottom; E. coli and CB1954 The drugs and their derivatives were detected by UV absorbance at 254 nm.

Figure 3

Figure 3. Schematic of drugs and proposed derivatives.

Structure prediction of drugs and derivatives based on mass spectrometry analysis. Hypothetical illustrations of structures based on elemental composition analysis and atomic mass fitting of HPLC peaks of drugs or drug derivatives after co-incubation with bacteria. For each molecule, its empirical formula and mass to charge ratio is also shown.

Figure 4

Figure 4. E. coli decreases the efficacy of gemcitabine in vivo.

Subcutaneous flank CT26 tumours growing in Balb/c mice were injected i.t with bacteria or PBS vehicle alone. Gemcitabine (60 mg/kg) was injected i.p. five times at three day intervals. (a) Tumour volume (%) relative to the first day of gemcitabine injection (day 0) is shown. *P < 0.03, **P = 0.002 (Bonferroni post hoc test) for gemcitabine alone versus gemcitabine + bacteria. (b) Kaplan-Meier plots showing mouse survival over time. The median survival post Day 0 of the gemcitabine + bacteria group was significantly less than that of the gemcitabine alone group (17 days vs. 28 days +/−1.25; P = 0.008). Data are expressed as mean ± SEM of 4 to 8 individual mice per group.

Figure 5

Figure 5. E. coli increases the cytotoxicity of CB1954.

Subcutaneous flank CT26 tumours growing in Balb/c mice were injected i.t with bacteria or PBS vehicle alone. CB1954 (20 mg/kg) was injected i.p. for the duration of the experiment at 3 day intervals. (a) Tumour volume (%) relative to the first day of CB1954 injection (day 0) is shown. (b) Kaplan-Meier plots showing mouse survival over time. The median survival post Day 0 of the CB1954 + bacteria group was significantly greater than that of the CB1954 alone group (26 days vs. 8 days. P = 0.0374). Data are expressed as mean ± SEM of 3-5 individual mice per group.

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