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Suicide Gene-Engineered Stromal Cells Reveal a Dynamic Regulation of Cancer Metastasis.

Shen K, Luk S, Elman J, Murray R, Mukundan S, Parekkadan B - Sci Rep (2016)

Bottom Line: Cancer-associated fibroblasts (CAFs) are a major cancer-promoting component in the tumor microenvironment (TME).Remarkably, we observed that the selective apoptosis of CAFs at these early timepoints did not affect primary tumor growth, but instead increased the presence of tumor-associated macrophages and the metastatic spread of breast cancer cells to the lung and bone.The study revealed a dynamic relationship between CAFs and cancer metastasis that has counter-intuitive ramifications for CAF-targeted therapy.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, Boston, Massachusetts 02114, USA.

ABSTRACT
Cancer-associated fibroblasts (CAFs) are a major cancer-promoting component in the tumor microenvironment (TME). The dynamic role of human CAFs in cancer progression has been ill-defined because human CAFs lack a unique marker needed for a cell-specific, promoter-driven knockout model. Here, we developed an engineered human CAF cell line with an inducible suicide gene to enable selective in vivo elimination of human CAFs at different stages of xenograft tumor development, effectively circumventing the challenge of targeting a cell-specific marker. Suicide-engineered CAFs were highly sensitive to apoptosis induction in vitro and in vivo by the addition of a simple small molecule inducer. Selection of timepoints for targeted CAF apoptosis in vivo during the progression of a human breast cancer xenograft model was guided by a bi-phasic host cytokine response that peaked at early timepoints after tumor implantation. Remarkably, we observed that the selective apoptosis of CAFs at these early timepoints did not affect primary tumor growth, but instead increased the presence of tumor-associated macrophages and the metastatic spread of breast cancer cells to the lung and bone. The study revealed a dynamic relationship between CAFs and cancer metastasis that has counter-intuitive ramifications for CAF-targeted therapy.

No MeSH data available.


Related in: MedlinePlus

Tumor growth dynamics and intratumor cytokine response to CAF elimination.(a) In an 8-week in vivo study of MDA/Luc+CAF-iCasp tumor growth, tumor size does not demonstrate visible changes until 43~53 days into the experiment measured by an arbitrary threshold (500 mm3). (b) A collection of host (mouse) cytokines with peak level at day 3 followed by steady decline into day 30. (c) A collection of host cytokines with initial increase to peak level at day 10 followed by steady decline into day 30.
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f3: Tumor growth dynamics and intratumor cytokine response to CAF elimination.(a) In an 8-week in vivo study of MDA/Luc+CAF-iCasp tumor growth, tumor size does not demonstrate visible changes until 43~53 days into the experiment measured by an arbitrary threshold (500 mm3). (b) A collection of host (mouse) cytokines with peak level at day 3 followed by steady decline into day 30. (c) A collection of host cytokines with initial increase to peak level at day 10 followed by steady decline into day 30.

Mentions: With confidence that we could specifically eliminate CAFs in vivo, the next objective was to determine when to eliminate CAF cells in the tumors in order to cause impactful changes in tumor development. We based this decision on the natural course of tumor dynamics. MDA/Luc were mixed with an equal number of CAF-iCasp cells and injected in the mammary fat pad of female NOD/SCID mice. Initial observation showed these co-implant xenograft tumors did not exhibit significant growth until 43~53 days into the experiment, with wide distribution of tumor sizes at any given time point during their exponential growth phase (Fig. 3a). On the other hand, morphological characterization (Fig. 2b) showed massive cancer cell growth (day 30) prior to apparent volumetric growth of tumor tissue. To better gauge tumor biology at a molecular and cellular level, we performed a multiplex cytokine analysis to determine the host (mouse) response to the co-implanted xenograft tumor on day 3, 10, 15, and 30. Surprisingly, we discovered two distinct classes of cytokine responses, namely a rapid response group (Fig. 3b) and a delayed response group (Fig. 3c). In the rapid response group, cytokines peaked on day 3, followed by a quick decline on day 10, and near-zero level on day 15 and 30. In the delayed response group, cytokines were initially relatively low, peaked on day 10, and then quickly declined by day 15. As most of these cytokines are associated with innate immunity, particularly macrophage functions, we hypothesized that day 3 and 10 represent critical turning points of the host immune reactions to the in vivo tumor development.


Suicide Gene-Engineered Stromal Cells Reveal a Dynamic Regulation of Cancer Metastasis.

Shen K, Luk S, Elman J, Murray R, Mukundan S, Parekkadan B - Sci Rep (2016)

Tumor growth dynamics and intratumor cytokine response to CAF elimination.(a) In an 8-week in vivo study of MDA/Luc+CAF-iCasp tumor growth, tumor size does not demonstrate visible changes until 43~53 days into the experiment measured by an arbitrary threshold (500 mm3). (b) A collection of host (mouse) cytokines with peak level at day 3 followed by steady decline into day 30. (c) A collection of host cytokines with initial increase to peak level at day 10 followed by steady decline into day 30.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759812&req=5

f3: Tumor growth dynamics and intratumor cytokine response to CAF elimination.(a) In an 8-week in vivo study of MDA/Luc+CAF-iCasp tumor growth, tumor size does not demonstrate visible changes until 43~53 days into the experiment measured by an arbitrary threshold (500 mm3). (b) A collection of host (mouse) cytokines with peak level at day 3 followed by steady decline into day 30. (c) A collection of host cytokines with initial increase to peak level at day 10 followed by steady decline into day 30.
Mentions: With confidence that we could specifically eliminate CAFs in vivo, the next objective was to determine when to eliminate CAF cells in the tumors in order to cause impactful changes in tumor development. We based this decision on the natural course of tumor dynamics. MDA/Luc were mixed with an equal number of CAF-iCasp cells and injected in the mammary fat pad of female NOD/SCID mice. Initial observation showed these co-implant xenograft tumors did not exhibit significant growth until 43~53 days into the experiment, with wide distribution of tumor sizes at any given time point during their exponential growth phase (Fig. 3a). On the other hand, morphological characterization (Fig. 2b) showed massive cancer cell growth (day 30) prior to apparent volumetric growth of tumor tissue. To better gauge tumor biology at a molecular and cellular level, we performed a multiplex cytokine analysis to determine the host (mouse) response to the co-implanted xenograft tumor on day 3, 10, 15, and 30. Surprisingly, we discovered two distinct classes of cytokine responses, namely a rapid response group (Fig. 3b) and a delayed response group (Fig. 3c). In the rapid response group, cytokines peaked on day 3, followed by a quick decline on day 10, and near-zero level on day 15 and 30. In the delayed response group, cytokines were initially relatively low, peaked on day 10, and then quickly declined by day 15. As most of these cytokines are associated with innate immunity, particularly macrophage functions, we hypothesized that day 3 and 10 represent critical turning points of the host immune reactions to the in vivo tumor development.

Bottom Line: Cancer-associated fibroblasts (CAFs) are a major cancer-promoting component in the tumor microenvironment (TME).Remarkably, we observed that the selective apoptosis of CAFs at these early timepoints did not affect primary tumor growth, but instead increased the presence of tumor-associated macrophages and the metastatic spread of breast cancer cells to the lung and bone.The study revealed a dynamic relationship between CAFs and cancer metastasis that has counter-intuitive ramifications for CAF-targeted therapy.

View Article: PubMed Central - PubMed

Affiliation: Department of Surgery, Center for Engineering in Medicine and Surgical Services, Massachusetts General Hospital, Harvard Medical School and the Shriners Hospitals for Children, Boston, Massachusetts 02114, USA.

ABSTRACT
Cancer-associated fibroblasts (CAFs) are a major cancer-promoting component in the tumor microenvironment (TME). The dynamic role of human CAFs in cancer progression has been ill-defined because human CAFs lack a unique marker needed for a cell-specific, promoter-driven knockout model. Here, we developed an engineered human CAF cell line with an inducible suicide gene to enable selective in vivo elimination of human CAFs at different stages of xenograft tumor development, effectively circumventing the challenge of targeting a cell-specific marker. Suicide-engineered CAFs were highly sensitive to apoptosis induction in vitro and in vivo by the addition of a simple small molecule inducer. Selection of timepoints for targeted CAF apoptosis in vivo during the progression of a human breast cancer xenograft model was guided by a bi-phasic host cytokine response that peaked at early timepoints after tumor implantation. Remarkably, we observed that the selective apoptosis of CAFs at these early timepoints did not affect primary tumor growth, but instead increased the presence of tumor-associated macrophages and the metastatic spread of breast cancer cells to the lung and bone. The study revealed a dynamic relationship between CAFs and cancer metastasis that has counter-intuitive ramifications for CAF-targeted therapy.

No MeSH data available.


Related in: MedlinePlus