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Reversing the aging stromal phenotype prevents carcinoma initiation.

Lewis DA, Travers JB, Machado C, Somani AK, Spandau DF - Aging (Albany NY) (2011)

Bottom Line: We hypothesized that commonly used therapeutic stromal wounding therapies can reduce the percentage of senescent fibroblasts and consequently prevent the formation of keratinocytes proliferating with DNA mutations following acute genotoxic (UVB) stress.In geriatric skin, we found that dermabrasion wounding decreases the proportion of senescent fibroblasts found in geriatric dermis, increases the expression of IGF-1, and restores the appropriate UVB response to epidermal keratinocytes in geriatric skin.Therefore, dermal rejuvenation therapies may play a significant role in preventing the initiation of skin cancer in geriatric patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, USA.

ABSTRACT
The accumulation of senescent stromal cells in aging tissue changes the local microenvironment from normal to a state similar to chronic inflammation. This inflammatory microenvironment can stimulate the proliferation of epithelial cells containing DNA mutations which can ultimately lead to cancer. Using geriatric skin as a model, we demonstrated that senescent fibroblasts also alter how epithelial keratinocytes respond to genotoxic stress, due to the silencing of IGF-1 expression in geriatric fibroblasts. These data indicate that in addition to promoting epithelial tumor growth, senescent fibroblasts also can promote carcinogenic initiation. We hypothesized that commonly used therapeutic stromal wounding therapies can reduce the percentage of senescent fibroblasts and consequently prevent the formation of keratinocytes proliferating with DNA mutations following acute genotoxic (UVB) stress. Sun-protected skin on the lower back of geriatric human volunteers was wounded by dermabrasion and the skin was allowed to heal for three months. In geriatric skin, we found that dermabrasion wounding decreases the proportion of senescent fibroblasts found in geriatric dermis, increases the expression of IGF-1, and restores the appropriate UVB response to epidermal keratinocytes in geriatric skin. Therefore, dermal rejuvenation therapies may play a significant role in preventing the initiation of skin cancer in geriatric patients.

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Senescent human fibroblasts contain markers of DNA damage response in vitro(A) Low passage neonatal normal human fibroblasts (PD-5), stress-induced senescent fibroblasts (PD-5, H2O2), and replicatively senescent fibroblasts (PD-40) were stained for the presence of senescence-associated β-galactosidase activity (blue), with α-53BP1 antibodies (multiple punctate nuclear staining), or α--p21 antibodies (bar = 20 µm). (B) The percentage of senescent cells were determined for senescence-associated β-galactosidase and 53BP1 staining. 53BP1-positive cells contained at least four individual fluorescent pin-point spots per nucleus (asterisks indicate significant difference from PD-5 cells, p <0.001, two-tailed t-test).
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Figure 1: Senescent human fibroblasts contain markers of DNA damage response in vitro(A) Low passage neonatal normal human fibroblasts (PD-5), stress-induced senescent fibroblasts (PD-5, H2O2), and replicatively senescent fibroblasts (PD-40) were stained for the presence of senescence-associated β-galactosidase activity (blue), with α-53BP1 antibodies (multiple punctate nuclear staining), or α--p21 antibodies (bar = 20 µm). (B) The percentage of senescent cells were determined for senescence-associated β-galactosidase and 53BP1 staining. 53BP1-positive cells contained at least four individual fluorescent pin-point spots per nucleus (asterisks indicate significant difference from PD-5 cells, p <0.001, two-tailed t-test).

Mentions: Normal human fibroblasts that are continually cultured in vitro until they reach replicative senescence have historically been identified by their expression of senescence-associated β-galactosidase [28]. Similarly, replicating fibroblasts treated with DNA-damaging chemotherapeutic drugs or pro-oxidative stressors to induce stress-induced senescence have been assayed for senescence-associated β-galactosidase activity to verify their senescence phenotype [3]. However, because identifying senescent cells using senescence-associated β-galactosidase requires an assay of enzymatic activity, its use in specimens from human tissues is not as effective. Recently, it has been described that markers of a DNA-damage response (DDR) are found in most types of senescent cells, whether induced by replication exhaustion, reactive oxygen species, or oncogene expression [29-32]. To determine the reliability of DDR markers to identify senescent fibroblasts in skin, replicating, stress-induced senescent, and replicative senescent fibroblasts were stained by for the traditional senescence-associated β-galactosidase activity, for the presence of 53BP1, and for the expression of cell cycle inhibitor p21 (Fig. 1A). As seen in Fig. 1A, senescent fibroblasts can be identified by nuclei which have greater than four 53BP1-positive foci. When the numbers of senescent fibroblasts were counted in stress-induced senescent and replicatively senescent fibroblasts, the use of either senescent-associated β-galactosidase or 53BP1 foci yielded similar results (Fig. 1B). Therefore, markers of DDR may be useful in identifying senescent fibroblasts in vivo.


Reversing the aging stromal phenotype prevents carcinoma initiation.

Lewis DA, Travers JB, Machado C, Somani AK, Spandau DF - Aging (Albany NY) (2011)

Senescent human fibroblasts contain markers of DNA damage response in vitro(A) Low passage neonatal normal human fibroblasts (PD-5), stress-induced senescent fibroblasts (PD-5, H2O2), and replicatively senescent fibroblasts (PD-40) were stained for the presence of senescence-associated β-galactosidase activity (blue), with α-53BP1 antibodies (multiple punctate nuclear staining), or α--p21 antibodies (bar = 20 µm). (B) The percentage of senescent cells were determined for senescence-associated β-galactosidase and 53BP1 staining. 53BP1-positive cells contained at least four individual fluorescent pin-point spots per nucleus (asterisks indicate significant difference from PD-5 cells, p <0.001, two-tailed t-test).
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3117456&req=5

Figure 1: Senescent human fibroblasts contain markers of DNA damage response in vitro(A) Low passage neonatal normal human fibroblasts (PD-5), stress-induced senescent fibroblasts (PD-5, H2O2), and replicatively senescent fibroblasts (PD-40) were stained for the presence of senescence-associated β-galactosidase activity (blue), with α-53BP1 antibodies (multiple punctate nuclear staining), or α--p21 antibodies (bar = 20 µm). (B) The percentage of senescent cells were determined for senescence-associated β-galactosidase and 53BP1 staining. 53BP1-positive cells contained at least four individual fluorescent pin-point spots per nucleus (asterisks indicate significant difference from PD-5 cells, p <0.001, two-tailed t-test).
Mentions: Normal human fibroblasts that are continually cultured in vitro until they reach replicative senescence have historically been identified by their expression of senescence-associated β-galactosidase [28]. Similarly, replicating fibroblasts treated with DNA-damaging chemotherapeutic drugs or pro-oxidative stressors to induce stress-induced senescence have been assayed for senescence-associated β-galactosidase activity to verify their senescence phenotype [3]. However, because identifying senescent cells using senescence-associated β-galactosidase requires an assay of enzymatic activity, its use in specimens from human tissues is not as effective. Recently, it has been described that markers of a DNA-damage response (DDR) are found in most types of senescent cells, whether induced by replication exhaustion, reactive oxygen species, or oncogene expression [29-32]. To determine the reliability of DDR markers to identify senescent fibroblasts in skin, replicating, stress-induced senescent, and replicative senescent fibroblasts were stained by for the traditional senescence-associated β-galactosidase activity, for the presence of 53BP1, and for the expression of cell cycle inhibitor p21 (Fig. 1A). As seen in Fig. 1A, senescent fibroblasts can be identified by nuclei which have greater than four 53BP1-positive foci. When the numbers of senescent fibroblasts were counted in stress-induced senescent and replicatively senescent fibroblasts, the use of either senescent-associated β-galactosidase or 53BP1 foci yielded similar results (Fig. 1B). Therefore, markers of DDR may be useful in identifying senescent fibroblasts in vivo.

Bottom Line: We hypothesized that commonly used therapeutic stromal wounding therapies can reduce the percentage of senescent fibroblasts and consequently prevent the formation of keratinocytes proliferating with DNA mutations following acute genotoxic (UVB) stress.In geriatric skin, we found that dermabrasion wounding decreases the proportion of senescent fibroblasts found in geriatric dermis, increases the expression of IGF-1, and restores the appropriate UVB response to epidermal keratinocytes in geriatric skin.Therefore, dermal rejuvenation therapies may play a significant role in preventing the initiation of skin cancer in geriatric patients.

View Article: PubMed Central - PubMed

Affiliation: Department of Dermatology, Indiana University School of Medicine, Indianapolis, Indiana, USA.

ABSTRACT
The accumulation of senescent stromal cells in aging tissue changes the local microenvironment from normal to a state similar to chronic inflammation. This inflammatory microenvironment can stimulate the proliferation of epithelial cells containing DNA mutations which can ultimately lead to cancer. Using geriatric skin as a model, we demonstrated that senescent fibroblasts also alter how epithelial keratinocytes respond to genotoxic stress, due to the silencing of IGF-1 expression in geriatric fibroblasts. These data indicate that in addition to promoting epithelial tumor growth, senescent fibroblasts also can promote carcinogenic initiation. We hypothesized that commonly used therapeutic stromal wounding therapies can reduce the percentage of senescent fibroblasts and consequently prevent the formation of keratinocytes proliferating with DNA mutations following acute genotoxic (UVB) stress. Sun-protected skin on the lower back of geriatric human volunteers was wounded by dermabrasion and the skin was allowed to heal for three months. In geriatric skin, we found that dermabrasion wounding decreases the proportion of senescent fibroblasts found in geriatric dermis, increases the expression of IGF-1, and restores the appropriate UVB response to epidermal keratinocytes in geriatric skin. Therefore, dermal rejuvenation therapies may play a significant role in preventing the initiation of skin cancer in geriatric patients.

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Related in: MedlinePlus