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Pronounced cancer resistance in a subterranean rodent, the blind mole-rat, Spalax: in vivo and in vitro evidence.

Manov I, Hirsh M, Iancu TC, Malik A, Sotnichenko N, Band M, Avivi A, Shams I - BMC Biol. (2013)

Bottom Line: This was accompanied by decreased cancer cell viability, reduced colony formation in soft agar, disturbed cell cycle progression, chromatin condensation and mitochondrial fragmentation.Spalax fibroblast conditioned media had no effect on proliferation of noncancerous cells.Obviously, along with adaptation to hypoxia, Spalax has evolved efficient anti-cancer mechanisms yet to be elucidated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Evolution, University of Haifa, Haifa 31095, Israel.

ABSTRACT

Background: Subterranean blind mole rats (Spalax) are hypoxia tolerant (down to 3% O2), long lived (>20 years) rodents showing no clear signs of aging or aging related disorders. In 50 years of Spalax research, spontaneous tumors have never been recorded among thousands of individuals. Here we addressed the questions of (1) whether Spalax is resistant to chemically-induced tumorigenesis, and (2) whether normal fibroblasts isolated from Spalax possess tumor-suppressive activity.

Results: Treating animals with 3-Methylcholantrene (3MCA) and 7,12-Dimethylbenz(a) anthracene/12-O-tetradecanoylphorbol-13-acetate (DMBA/TPA), two potent carcinogens, confirmed Spalax high resistance to chemically induced cancers. While all mice and rats developed the expected tumors following treatment with both carcinogens, among Spalax no tumors were observed after DMBA/TPA treatment, while 3MCA induced benign fibroblastic proliferation in 2 Spalax individuals out of12, and only a single animal from the advanced age group developed malignancy 18 months post-treatment. The remaining animals are still healthy 30 months post-treatment. In vitro experiments showed an extraordinary ability of normal Spalax cultured fibroblasts to restrict malignant behavior in a broad spectrum of human-derived and in newly isolated Spalax 3MCA-induced cancer cell lines. Growth of cancer cells was inhibited by either direct interaction with Spalax fibroblasts or with soluble factors released into culture media and soft agar. This was accompanied by decreased cancer cell viability, reduced colony formation in soft agar, disturbed cell cycle progression, chromatin condensation and mitochondrial fragmentation. Cells from another cancer resistant subterranean mammal, the naked mole rat, were also tested for direct effect on cancer cells and, similar to Spalax, demonstrated anti-cancer activity. No effect on cancer cells was observed using fibroblasts from mouse, rat or Acomys. Spalax fibroblast conditioned media had no effect on proliferation of noncancerous cells.

Conclusions: This report provides pioneering evidence that Spalax is not only resistant to spontaneous cancer but also to experimentally induced cancer, and shows the unique ability of Spalax normal fibroblasts to inhibit growth and kill cancer cells, but not normal cells, either through direct fibroblast-cancer cell interaction or via soluble factors. Obviously, along with adaptation to hypoxia, Spalax has evolved efficient anti-cancer mechanisms yet to be elucidated. Exploring the molecular mechanisms allowing Spalax to survive in extreme environments and to escape cancer as well as to kill homologous and heterologous cancer cells may hold the key for understanding the molecular nature of host resistance to cancer and identify new anti-cancer strategies for treating humans.

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Spalax fibroblasts suppress colony formation of human breast cancer cells MDA-MB-231 and MCF7 in soft agar. (A) MDA-MB-231 cells (5 × 103 cells) cells were suspended in 0.35% agar and added as the cancer cell top layer to base layer either empty (blank) or containing the Spalax or rat fibroblast monolayer. At Day 21, colonies larger than 50 μm were counted under an inverted microscope and photographed (×40). Representative microscopic images out of 15 fields are shown. (B) Average number of colonies counted in soft agar (n = 15). The experiment was performed in duplicate plates at least three times; mean ± S.D. (C) A representative colony in soft agar was formed by MDA-MB-231 only, or by co-culturing with a Spalax fibroblast monolayer. The size bar shows equivalent magnification in both images (× 200). (D) MCF7 cells (5 × 103 cells) were grown in soft agar on top of a monolayer of mouse newborn (MNbF), or Spalax newborn fibroblasts (SpNbF) in 35-mm culture dishes. After 5 and 11 days of incubation colonies containing >20 cells were counted by using an inverted microscope (× 200), mean ± S.D.
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Figure 10: Spalax fibroblasts suppress colony formation of human breast cancer cells MDA-MB-231 and MCF7 in soft agar. (A) MDA-MB-231 cells (5 × 103 cells) cells were suspended in 0.35% agar and added as the cancer cell top layer to base layer either empty (blank) or containing the Spalax or rat fibroblast monolayer. At Day 21, colonies larger than 50 μm were counted under an inverted microscope and photographed (×40). Representative microscopic images out of 15 fields are shown. (B) Average number of colonies counted in soft agar (n = 15). The experiment was performed in duplicate plates at least three times; mean ± S.D. (C) A representative colony in soft agar was formed by MDA-MB-231 only, or by co-culturing with a Spalax fibroblast monolayer. The size bar shows equivalent magnification in both images (× 200). (D) MCF7 cells (5 × 103 cells) were grown in soft agar on top of a monolayer of mouse newborn (MNbF), or Spalax newborn fibroblasts (SpNbF) in 35-mm culture dishes. After 5 and 11 days of incubation colonies containing >20 cells were counted by using an inverted microscope (× 200), mean ± S.D.

Mentions: To study whether soluble factors generated by Spalax fibroblasts may influence colony formation in soft agar, breast cancer cells were cultivated for three weeks in the absence or presence of Spalax fibroblasts (Figure 10). Spalax fibroblasts strongly reduced the formation of MDA-MB-231 colonies (Figure 10A,B). The ability of MDA-MB-231 to form large colonies was completely inhibited by Spalax fibroblasts (Figure 10C), while rat fibroblasts had no effect on colony formation (Figure 10A,B). Cells from another human breast cancer cell line, MCF-7, were incubated with monolayers of Spalax and mouse fibroblasts (Figure 10D). Remarkably, after 11 days, and compared to the control, more colonies were formed when human MCF7 cells were co-cultured with mouse fibroblasts, whereas a monolayer of Spalax fibroblasts significantly reduced MCF7 colony-formation.


Pronounced cancer resistance in a subterranean rodent, the blind mole-rat, Spalax: in vivo and in vitro evidence.

Manov I, Hirsh M, Iancu TC, Malik A, Sotnichenko N, Band M, Avivi A, Shams I - BMC Biol. (2013)

Spalax fibroblasts suppress colony formation of human breast cancer cells MDA-MB-231 and MCF7 in soft agar. (A) MDA-MB-231 cells (5 × 103 cells) cells were suspended in 0.35% agar and added as the cancer cell top layer to base layer either empty (blank) or containing the Spalax or rat fibroblast monolayer. At Day 21, colonies larger than 50 μm were counted under an inverted microscope and photographed (×40). Representative microscopic images out of 15 fields are shown. (B) Average number of colonies counted in soft agar (n = 15). The experiment was performed in duplicate plates at least three times; mean ± S.D. (C) A representative colony in soft agar was formed by MDA-MB-231 only, or by co-culturing with a Spalax fibroblast monolayer. The size bar shows equivalent magnification in both images (× 200). (D) MCF7 cells (5 × 103 cells) were grown in soft agar on top of a monolayer of mouse newborn (MNbF), or Spalax newborn fibroblasts (SpNbF) in 35-mm culture dishes. After 5 and 11 days of incubation colonies containing >20 cells were counted by using an inverted microscope (× 200), mean ± S.D.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3750378&req=5

Figure 10: Spalax fibroblasts suppress colony formation of human breast cancer cells MDA-MB-231 and MCF7 in soft agar. (A) MDA-MB-231 cells (5 × 103 cells) cells were suspended in 0.35% agar and added as the cancer cell top layer to base layer either empty (blank) or containing the Spalax or rat fibroblast monolayer. At Day 21, colonies larger than 50 μm were counted under an inverted microscope and photographed (×40). Representative microscopic images out of 15 fields are shown. (B) Average number of colonies counted in soft agar (n = 15). The experiment was performed in duplicate plates at least three times; mean ± S.D. (C) A representative colony in soft agar was formed by MDA-MB-231 only, or by co-culturing with a Spalax fibroblast monolayer. The size bar shows equivalent magnification in both images (× 200). (D) MCF7 cells (5 × 103 cells) were grown in soft agar on top of a monolayer of mouse newborn (MNbF), or Spalax newborn fibroblasts (SpNbF) in 35-mm culture dishes. After 5 and 11 days of incubation colonies containing >20 cells were counted by using an inverted microscope (× 200), mean ± S.D.
Mentions: To study whether soluble factors generated by Spalax fibroblasts may influence colony formation in soft agar, breast cancer cells were cultivated for three weeks in the absence or presence of Spalax fibroblasts (Figure 10). Spalax fibroblasts strongly reduced the formation of MDA-MB-231 colonies (Figure 10A,B). The ability of MDA-MB-231 to form large colonies was completely inhibited by Spalax fibroblasts (Figure 10C), while rat fibroblasts had no effect on colony formation (Figure 10A,B). Cells from another human breast cancer cell line, MCF-7, were incubated with monolayers of Spalax and mouse fibroblasts (Figure 10D). Remarkably, after 11 days, and compared to the control, more colonies were formed when human MCF7 cells were co-cultured with mouse fibroblasts, whereas a monolayer of Spalax fibroblasts significantly reduced MCF7 colony-formation.

Bottom Line: This was accompanied by decreased cancer cell viability, reduced colony formation in soft agar, disturbed cell cycle progression, chromatin condensation and mitochondrial fragmentation.Spalax fibroblast conditioned media had no effect on proliferation of noncancerous cells.Obviously, along with adaptation to hypoxia, Spalax has evolved efficient anti-cancer mechanisms yet to be elucidated.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institute of Evolution, University of Haifa, Haifa 31095, Israel.

ABSTRACT

Background: Subterranean blind mole rats (Spalax) are hypoxia tolerant (down to 3% O2), long lived (>20 years) rodents showing no clear signs of aging or aging related disorders. In 50 years of Spalax research, spontaneous tumors have never been recorded among thousands of individuals. Here we addressed the questions of (1) whether Spalax is resistant to chemically-induced tumorigenesis, and (2) whether normal fibroblasts isolated from Spalax possess tumor-suppressive activity.

Results: Treating animals with 3-Methylcholantrene (3MCA) and 7,12-Dimethylbenz(a) anthracene/12-O-tetradecanoylphorbol-13-acetate (DMBA/TPA), two potent carcinogens, confirmed Spalax high resistance to chemically induced cancers. While all mice and rats developed the expected tumors following treatment with both carcinogens, among Spalax no tumors were observed after DMBA/TPA treatment, while 3MCA induced benign fibroblastic proliferation in 2 Spalax individuals out of12, and only a single animal from the advanced age group developed malignancy 18 months post-treatment. The remaining animals are still healthy 30 months post-treatment. In vitro experiments showed an extraordinary ability of normal Spalax cultured fibroblasts to restrict malignant behavior in a broad spectrum of human-derived and in newly isolated Spalax 3MCA-induced cancer cell lines. Growth of cancer cells was inhibited by either direct interaction with Spalax fibroblasts or with soluble factors released into culture media and soft agar. This was accompanied by decreased cancer cell viability, reduced colony formation in soft agar, disturbed cell cycle progression, chromatin condensation and mitochondrial fragmentation. Cells from another cancer resistant subterranean mammal, the naked mole rat, were also tested for direct effect on cancer cells and, similar to Spalax, demonstrated anti-cancer activity. No effect on cancer cells was observed using fibroblasts from mouse, rat or Acomys. Spalax fibroblast conditioned media had no effect on proliferation of noncancerous cells.

Conclusions: This report provides pioneering evidence that Spalax is not only resistant to spontaneous cancer but also to experimentally induced cancer, and shows the unique ability of Spalax normal fibroblasts to inhibit growth and kill cancer cells, but not normal cells, either through direct fibroblast-cancer cell interaction or via soluble factors. Obviously, along with adaptation to hypoxia, Spalax has evolved efficient anti-cancer mechanisms yet to be elucidated. Exploring the molecular mechanisms allowing Spalax to survive in extreme environments and to escape cancer as well as to kill homologous and heterologous cancer cells may hold the key for understanding the molecular nature of host resistance to cancer and identify new anti-cancer strategies for treating humans.

Show MeSH
Related in: MedlinePlus