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Rapamycin Promotes Mouse 4T1 Tumor Metastasis that Can Be Reversed by a Dendritic Cell-Based Vaccine.

Lin TJ, Liang WM, Hsiao PW, M S P, Wei WC, Lin HT, Yin SY, Yang NS - PLoS ONE (2015)

Bottom Line: Suppression of tumor metastasis is a key strategy for successful cancer interventions.However, rapamycin also exhibits immunosuppressant effects and is hence used clinically as an organ transplantation drug.We hypothesized that the immunosuppressive activities of rapamycin might also negatively mediate host immunity, resulting in promotion of tumor metastasis.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Injury Prevention and Control, Taipei Medical University, Taipei, Taiwan, ROC; Department of Neurosurgery, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan, ROC; Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, ROC; Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, ROC; Taiwan International Graduate Program (TIGP), Molecular and Biological Agricultural Sciences Program, Academia Sinica, Taipei, Taiwan, ROC.

ABSTRACT
Suppression of tumor metastasis is a key strategy for successful cancer interventions. Previous studies indicated that rapamycin (sirolimus) may promote tumor regression activity or enhance immune response against tumor targets. However, rapamycin also exhibits immunosuppressant effects and is hence used clinically as an organ transplantation drug. We hypothesized that the immunosuppressive activities of rapamycin might also negatively mediate host immunity, resulting in promotion of tumor metastasis. In this study, the effects of rapamycin and phytochemical shikonin were investigated in vitro and in vivo in a 4T1 mouse mammary tumor model through quantitative assessment of immunogenic cell death (ICD), autophagy, tumor growth and metastasis. Tumor-bearing mice were immunized with test vaccines to monitor their effect on tumor metastasis. We found that intraperitoneal (ip) administration of rapamycin after a tumor-resection surgery drastically increased the metastatic activity of 4T1 tumors. Possible correlation of this finding to human cancers was suggested by epidemiological analysis of data from Taiwan's National Health Insurance Research Database (NHIRD). Since our previous studies showed that modified tumor cell lysate (TCL)-pulsed, dendritic cell (DC)-based cancer vaccines can effectively suppress metastasis in mouse tumor models, we assessed whether such vaccines may help offset this rapamycin-promoted metastasis. We observed that shikonin efficiently induced ICD of 4T1 cells in culture, and DC vaccines pulsed with shikonin-treated TCL (SK-TCL-DC) significantly suppressed rapamycin-enhanced metastasis and Treg cell expansion in test mice. In conclusion, rapamycin treatment in mice (and perhaps in humans) promotes metastasis and the effect may be offset by treatment with a DC-based cancer vaccine.

No MeSH data available.


Related in: MedlinePlus

Administration of rapamycin in vivo promotes metastasis of 4T1 cells in a tumor resection mouse model.(A), Schema for treatment. Mice were injected subcutaneously with 4T1-Luc2 cells (5 × 105 cells/100 μl PBS/mouse) into mammary fat pad under isoflurane anesthesia at day 0. At 16 days post tumor cell implantation, primary tumors were surgically resected. Test mice were administered with saline, Rapamycin (0.75 mg/kg) or rapamycin-dissolving solvent (vehicle control, 4% ethanol, 5% polyethylene glycol 400, and 5% Tween 80) by intravenous injection for 3 weeks (3 injections/week). (B), Representative in vivo bioluminescent images of test mice (n = 8) treated with saline, rapamycin and vehicle control solvent at 4 weeks post tumor resection. The red signals represent the highest level on the colorimetric scale. Labelling with “D” in photograph denotes the mice that had died before 4 weeks post tumor resection. (C), Quantification of tumor metastasis burden in mice treated within the indicated time course as revealed by bioluminescence imaging for luciferase activity. (D), Survival time of mice after treatment with the indicated test agents. *, the p values, P < 0.05, when the rapamycin-treated group was compared with the vehicle (dissolving solvent) control group.
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pone.0138335.g002: Administration of rapamycin in vivo promotes metastasis of 4T1 cells in a tumor resection mouse model.(A), Schema for treatment. Mice were injected subcutaneously with 4T1-Luc2 cells (5 × 105 cells/100 μl PBS/mouse) into mammary fat pad under isoflurane anesthesia at day 0. At 16 days post tumor cell implantation, primary tumors were surgically resected. Test mice were administered with saline, Rapamycin (0.75 mg/kg) or rapamycin-dissolving solvent (vehicle control, 4% ethanol, 5% polyethylene glycol 400, and 5% Tween 80) by intravenous injection for 3 weeks (3 injections/week). (B), Representative in vivo bioluminescent images of test mice (n = 8) treated with saline, rapamycin and vehicle control solvent at 4 weeks post tumor resection. The red signals represent the highest level on the colorimetric scale. Labelling with “D” in photograph denotes the mice that had died before 4 weeks post tumor resection. (C), Quantification of tumor metastasis burden in mice treated within the indicated time course as revealed by bioluminescence imaging for luciferase activity. (D), Survival time of mice after treatment with the indicated test agents. *, the p values, P < 0.05, when the rapamycin-treated group was compared with the vehicle (dissolving solvent) control group.

Mentions: To effectively evaluate the effect of rapamycin on mammary tumor metastasis, we used a bioluminescent, transgenic luciferase-labelled 4T1 mouse mammary carcinoma cell line (developed by Dr. P.W. Hsiao of Academia Sinica, Taiwan (see Materials and Methods), and the subsequent 4T1 tumor metastasis model in BALB/c mice. After resection of the orthotopic primary tumors, test mice were treated with saline, rapamycin (0.75 mg/kg) and the rapamycin-dissolving solvent (as vehicle control, containing 4% ethanol, 5% polyethylene glycol 400, and 5% Tween 80), were monitored and compared for bioluminescent images of 4T1 tumors in a time course experiment (Fig 2). In comparison, rapamycin treatment resulted in a significant increase in the level of 4T1 tumor metastasis, as compared with the saline and vehicle control treatments (Fig 2B and 2C). Consistently, rapamycin treatment also significantly decreased the life span of test mice as compared to the PBS (P < 0.05) and vehicle control treatment (P < 0.05) (Fig 2D). These results of Fig 2 together show that rapamycin treatment can effectively promote 4T1 tumor metastasis into lung, when used in combination with a resection process for primary mammary tumor. In another experiment, effect of docetaxol as a positive control for anti-4T1 metastasis in our tumor-resection study model was conducted, indicating the detectable therapeutic effect of a chemotherapy drug in our in vivo study model (S2 Fig).


Rapamycin Promotes Mouse 4T1 Tumor Metastasis that Can Be Reversed by a Dendritic Cell-Based Vaccine.

Lin TJ, Liang WM, Hsiao PW, M S P, Wei WC, Lin HT, Yin SY, Yang NS - PLoS ONE (2015)

Administration of rapamycin in vivo promotes metastasis of 4T1 cells in a tumor resection mouse model.(A), Schema for treatment. Mice were injected subcutaneously with 4T1-Luc2 cells (5 × 105 cells/100 μl PBS/mouse) into mammary fat pad under isoflurane anesthesia at day 0. At 16 days post tumor cell implantation, primary tumors were surgically resected. Test mice were administered with saline, Rapamycin (0.75 mg/kg) or rapamycin-dissolving solvent (vehicle control, 4% ethanol, 5% polyethylene glycol 400, and 5% Tween 80) by intravenous injection for 3 weeks (3 injections/week). (B), Representative in vivo bioluminescent images of test mice (n = 8) treated with saline, rapamycin and vehicle control solvent at 4 weeks post tumor resection. The red signals represent the highest level on the colorimetric scale. Labelling with “D” in photograph denotes the mice that had died before 4 weeks post tumor resection. (C), Quantification of tumor metastasis burden in mice treated within the indicated time course as revealed by bioluminescence imaging for luciferase activity. (D), Survival time of mice after treatment with the indicated test agents. *, the p values, P < 0.05, when the rapamycin-treated group was compared with the vehicle (dissolving solvent) control group.
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pone.0138335.g002: Administration of rapamycin in vivo promotes metastasis of 4T1 cells in a tumor resection mouse model.(A), Schema for treatment. Mice were injected subcutaneously with 4T1-Luc2 cells (5 × 105 cells/100 μl PBS/mouse) into mammary fat pad under isoflurane anesthesia at day 0. At 16 days post tumor cell implantation, primary tumors were surgically resected. Test mice were administered with saline, Rapamycin (0.75 mg/kg) or rapamycin-dissolving solvent (vehicle control, 4% ethanol, 5% polyethylene glycol 400, and 5% Tween 80) by intravenous injection for 3 weeks (3 injections/week). (B), Representative in vivo bioluminescent images of test mice (n = 8) treated with saline, rapamycin and vehicle control solvent at 4 weeks post tumor resection. The red signals represent the highest level on the colorimetric scale. Labelling with “D” in photograph denotes the mice that had died before 4 weeks post tumor resection. (C), Quantification of tumor metastasis burden in mice treated within the indicated time course as revealed by bioluminescence imaging for luciferase activity. (D), Survival time of mice after treatment with the indicated test agents. *, the p values, P < 0.05, when the rapamycin-treated group was compared with the vehicle (dissolving solvent) control group.
Mentions: To effectively evaluate the effect of rapamycin on mammary tumor metastasis, we used a bioluminescent, transgenic luciferase-labelled 4T1 mouse mammary carcinoma cell line (developed by Dr. P.W. Hsiao of Academia Sinica, Taiwan (see Materials and Methods), and the subsequent 4T1 tumor metastasis model in BALB/c mice. After resection of the orthotopic primary tumors, test mice were treated with saline, rapamycin (0.75 mg/kg) and the rapamycin-dissolving solvent (as vehicle control, containing 4% ethanol, 5% polyethylene glycol 400, and 5% Tween 80), were monitored and compared for bioluminescent images of 4T1 tumors in a time course experiment (Fig 2). In comparison, rapamycin treatment resulted in a significant increase in the level of 4T1 tumor metastasis, as compared with the saline and vehicle control treatments (Fig 2B and 2C). Consistently, rapamycin treatment also significantly decreased the life span of test mice as compared to the PBS (P < 0.05) and vehicle control treatment (P < 0.05) (Fig 2D). These results of Fig 2 together show that rapamycin treatment can effectively promote 4T1 tumor metastasis into lung, when used in combination with a resection process for primary mammary tumor. In another experiment, effect of docetaxol as a positive control for anti-4T1 metastasis in our tumor-resection study model was conducted, indicating the detectable therapeutic effect of a chemotherapy drug in our in vivo study model (S2 Fig).

Bottom Line: Suppression of tumor metastasis is a key strategy for successful cancer interventions.However, rapamycin also exhibits immunosuppressant effects and is hence used clinically as an organ transplantation drug.We hypothesized that the immunosuppressive activities of rapamycin might also negatively mediate host immunity, resulting in promotion of tumor metastasis.

View Article: PubMed Central - PubMed

Affiliation: Graduate Institute of Injury Prevention and Control, Taipei Medical University, Taipei, Taiwan, ROC; Department of Neurosurgery, Taipei Medical University-Wan Fang Hospital, Taipei, Taiwan, ROC; Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan, ROC; Graduate Institute of Biotechnology, National Chung Hsing University, Taichung, Taiwan, ROC; Taiwan International Graduate Program (TIGP), Molecular and Biological Agricultural Sciences Program, Academia Sinica, Taipei, Taiwan, ROC.

ABSTRACT
Suppression of tumor metastasis is a key strategy for successful cancer interventions. Previous studies indicated that rapamycin (sirolimus) may promote tumor regression activity or enhance immune response against tumor targets. However, rapamycin also exhibits immunosuppressant effects and is hence used clinically as an organ transplantation drug. We hypothesized that the immunosuppressive activities of rapamycin might also negatively mediate host immunity, resulting in promotion of tumor metastasis. In this study, the effects of rapamycin and phytochemical shikonin were investigated in vitro and in vivo in a 4T1 mouse mammary tumor model through quantitative assessment of immunogenic cell death (ICD), autophagy, tumor growth and metastasis. Tumor-bearing mice were immunized with test vaccines to monitor their effect on tumor metastasis. We found that intraperitoneal (ip) administration of rapamycin after a tumor-resection surgery drastically increased the metastatic activity of 4T1 tumors. Possible correlation of this finding to human cancers was suggested by epidemiological analysis of data from Taiwan's National Health Insurance Research Database (NHIRD). Since our previous studies showed that modified tumor cell lysate (TCL)-pulsed, dendritic cell (DC)-based cancer vaccines can effectively suppress metastasis in mouse tumor models, we assessed whether such vaccines may help offset this rapamycin-promoted metastasis. We observed that shikonin efficiently induced ICD of 4T1 cells in culture, and DC vaccines pulsed with shikonin-treated TCL (SK-TCL-DC) significantly suppressed rapamycin-enhanced metastasis and Treg cell expansion in test mice. In conclusion, rapamycin treatment in mice (and perhaps in humans) promotes metastasis and the effect may be offset by treatment with a DC-based cancer vaccine.

No MeSH data available.


Related in: MedlinePlus