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SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas.

Hussenet T, Dali S, Exinger J, Monga B, Jost B, Dembelé D, Martinet N, Thibault C, Huelsken J, Brambilla E, du Manoir S - PLoS ONE (2010)

Bottom Line: Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2.In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth.These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.

View Article: PubMed Central - PubMed

Affiliation: Département Biologie du Cancer, Institut National de la Santé et de la Recherche Médicale, Institut de Génétique et de Biologie Moléculaire et Cellulaire, U964 Illkirch, France. hussenet@igbmc.fr

ABSTRACT
Squamous cell carcinoma (SCC) of the lung is a frequent and aggressive cancer type. Gene amplifications, a known activating mechanism of oncogenes, target the 3q26-qter region as one of the most frequently gained/amplified genomic sites in SCC of various types. Here, we used array comparative genomic hybridization to delineate the consensus region of 3q26.3 amplifications in lung SCC. Recurrent amplifications occur in 20% of lung SCC (136 tumors in total) and map to a core region of 2 Mb (Megabases) that encompasses SOX2, a transcription factor gene. Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2. Analyses of the transcriptome of lung SCC, SOX2-overexpressing lung epithelial cells and embryonic stem cells (ESCs) reveal that SOX2 contributes to activate ESC-like phenotypes and provide clues pertaining to the deregulated genes involved in the malignant phenotype. In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth. Finally, SOX2 over-expression in non-tumorigenic human lung bronchial epithelial cells is tumorigenic in immunocompromised mice. These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.

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Consequences of Sox2 over-expression in vivo.A. Tumor incidence upon subcutaneous implantation of human lung squamous control- and SOX2-transduced cell lines in nude mice. For each cell line, the number of tumors that developed is represented with respect to the number of injections for each cell type (control or SOX2-transduced, n = 4 injected animals each). Tumor incidence is unchanged for the NCI-H226 highly tumorigenic cell line, whereas BEAS-2B cells become tumorigenic upon Sox2 over-expression. B. Hematoxylin and Eosin (H&E) staining of a representative area of a BEAS-2B-Sox2 subcutaneous tumor (magnification = 100×). A majority of the tumor area (around 80%) has typical traits of poorly differentiated basaloid variants of squamous cell carcinoma. C. H&E staining of representative areas of the same BEAS-2B-Sox2 subcutaneous tumor as in panel B (magnification = 100×). Around 20% of the tumor area has typical traits of poorly to moderately differentiated squamous cell carcinoma, with individual cell keratinization. D. H&E staining of one BEAS-2B-Sox2 subcutaneous tumor (magnification = 50×). In this case, local tumor cell invasion into the dermis was observed (arrowheads). E. Immunohistochemistry for SOX2, Keratins 5/6 and Ki67 (left, middle and right panels, respectively; magnifications = 200×). Tumors homogeneously express SOX2 and Ki67 and heterogeneously express Keratins 5/6, which are squamous cell differentiation markers.
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pone-0008960-g007: Consequences of Sox2 over-expression in vivo.A. Tumor incidence upon subcutaneous implantation of human lung squamous control- and SOX2-transduced cell lines in nude mice. For each cell line, the number of tumors that developed is represented with respect to the number of injections for each cell type (control or SOX2-transduced, n = 4 injected animals each). Tumor incidence is unchanged for the NCI-H226 highly tumorigenic cell line, whereas BEAS-2B cells become tumorigenic upon Sox2 over-expression. B. Hematoxylin and Eosin (H&E) staining of a representative area of a BEAS-2B-Sox2 subcutaneous tumor (magnification = 100×). A majority of the tumor area (around 80%) has typical traits of poorly differentiated basaloid variants of squamous cell carcinoma. C. H&E staining of representative areas of the same BEAS-2B-Sox2 subcutaneous tumor as in panel B (magnification = 100×). Around 20% of the tumor area has typical traits of poorly to moderately differentiated squamous cell carcinoma, with individual cell keratinization. D. H&E staining of one BEAS-2B-Sox2 subcutaneous tumor (magnification = 50×). In this case, local tumor cell invasion into the dermis was observed (arrowheads). E. Immunohistochemistry for SOX2, Keratins 5/6 and Ki67 (left, middle and right panels, respectively; magnifications = 200×). Tumors homogeneously express SOX2 and Ki67 and heterogeneously express Keratins 5/6, which are squamous cell differentiation markers.

Mentions: Therefore, we implanted transduced cells in vivo to assess the effect of Sox2 over-expression on tumor formation and growth in immunocompromised mice injected subcutaneously. The highly tumorigenic NCI-H226 cells lead to systematic tumor growth with no change in growth rate according to SOX2 status (Figure 7 panel A). By contrast, BEAS-2B-SOX2 cells gave rise to tumors in all four injected animals, in contrast to control cells (Figure 7 panel A–D). The BEAS-2B-SOX2-derived tumors grew relatively slowly: volumes reached 0.25–1 cm3 within 3 to 6 months. This finding strongly suggests that additional hits downstream of SOX2 over-expression might be required to allow for full transformation of BEAS-2B cells and tumor expansion in vivo. At the histological level (Figure 7 panel B), the tumors were mainly composed of poorly differentiated SCC of the basaloid subtype [33]. Remarkably, within the same tumor, restricted areas (about 20% of the tumor section surface) displayed well- or moderately-differentiated features with individual cell keratinization (Figure 7 panel C), which is commonly seen in human basaloid variants of SCC [34]. Interestingly, local invasion of tumor cells into the dermis was also noted in one case (Figure 7 panel D). At the molecular level, low levels of apoptosis were noted (as assessed by cleaved caspase-3 staining; data not shown). The tumor cells homogeneously expressed nuclear SOX2, and most of them were cycling, as assessed by Ki67 staining. Further, keratins 5/6, which are squamous differentiation markers, were heterogeneously expressed (Figure 7 panel E). In conclusion, Sox2 over-expression is capable of converting non-tumorigenic human lung bronchial epithelial cells to a tumorigenic state, enabling them to grow as poorly differentiated squamous tumors in immunocompromised mice.


SOX2 is an oncogene activated by recurrent 3q26.3 amplifications in human lung squamous cell carcinomas.

Hussenet T, Dali S, Exinger J, Monga B, Jost B, Dembelé D, Martinet N, Thibault C, Huelsken J, Brambilla E, du Manoir S - PLoS ONE (2010)

Consequences of Sox2 over-expression in vivo.A. Tumor incidence upon subcutaneous implantation of human lung squamous control- and SOX2-transduced cell lines in nude mice. For each cell line, the number of tumors that developed is represented with respect to the number of injections for each cell type (control or SOX2-transduced, n = 4 injected animals each). Tumor incidence is unchanged for the NCI-H226 highly tumorigenic cell line, whereas BEAS-2B cells become tumorigenic upon Sox2 over-expression. B. Hematoxylin and Eosin (H&E) staining of a representative area of a BEAS-2B-Sox2 subcutaneous tumor (magnification = 100×). A majority of the tumor area (around 80%) has typical traits of poorly differentiated basaloid variants of squamous cell carcinoma. C. H&E staining of representative areas of the same BEAS-2B-Sox2 subcutaneous tumor as in panel B (magnification = 100×). Around 20% of the tumor area has typical traits of poorly to moderately differentiated squamous cell carcinoma, with individual cell keratinization. D. H&E staining of one BEAS-2B-Sox2 subcutaneous tumor (magnification = 50×). In this case, local tumor cell invasion into the dermis was observed (arrowheads). E. Immunohistochemistry for SOX2, Keratins 5/6 and Ki67 (left, middle and right panels, respectively; magnifications = 200×). Tumors homogeneously express SOX2 and Ki67 and heterogeneously express Keratins 5/6, which are squamous cell differentiation markers.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2813300&req=5

pone-0008960-g007: Consequences of Sox2 over-expression in vivo.A. Tumor incidence upon subcutaneous implantation of human lung squamous control- and SOX2-transduced cell lines in nude mice. For each cell line, the number of tumors that developed is represented with respect to the number of injections for each cell type (control or SOX2-transduced, n = 4 injected animals each). Tumor incidence is unchanged for the NCI-H226 highly tumorigenic cell line, whereas BEAS-2B cells become tumorigenic upon Sox2 over-expression. B. Hematoxylin and Eosin (H&E) staining of a representative area of a BEAS-2B-Sox2 subcutaneous tumor (magnification = 100×). A majority of the tumor area (around 80%) has typical traits of poorly differentiated basaloid variants of squamous cell carcinoma. C. H&E staining of representative areas of the same BEAS-2B-Sox2 subcutaneous tumor as in panel B (magnification = 100×). Around 20% of the tumor area has typical traits of poorly to moderately differentiated squamous cell carcinoma, with individual cell keratinization. D. H&E staining of one BEAS-2B-Sox2 subcutaneous tumor (magnification = 50×). In this case, local tumor cell invasion into the dermis was observed (arrowheads). E. Immunohistochemistry for SOX2, Keratins 5/6 and Ki67 (left, middle and right panels, respectively; magnifications = 200×). Tumors homogeneously express SOX2 and Ki67 and heterogeneously express Keratins 5/6, which are squamous cell differentiation markers.
Mentions: Therefore, we implanted transduced cells in vivo to assess the effect of Sox2 over-expression on tumor formation and growth in immunocompromised mice injected subcutaneously. The highly tumorigenic NCI-H226 cells lead to systematic tumor growth with no change in growth rate according to SOX2 status (Figure 7 panel A). By contrast, BEAS-2B-SOX2 cells gave rise to tumors in all four injected animals, in contrast to control cells (Figure 7 panel A–D). The BEAS-2B-SOX2-derived tumors grew relatively slowly: volumes reached 0.25–1 cm3 within 3 to 6 months. This finding strongly suggests that additional hits downstream of SOX2 over-expression might be required to allow for full transformation of BEAS-2B cells and tumor expansion in vivo. At the histological level (Figure 7 panel B), the tumors were mainly composed of poorly differentiated SCC of the basaloid subtype [33]. Remarkably, within the same tumor, restricted areas (about 20% of the tumor section surface) displayed well- or moderately-differentiated features with individual cell keratinization (Figure 7 panel C), which is commonly seen in human basaloid variants of SCC [34]. Interestingly, local invasion of tumor cells into the dermis was also noted in one case (Figure 7 panel D). At the molecular level, low levels of apoptosis were noted (as assessed by cleaved caspase-3 staining; data not shown). The tumor cells homogeneously expressed nuclear SOX2, and most of them were cycling, as assessed by Ki67 staining. Further, keratins 5/6, which are squamous differentiation markers, were heterogeneously expressed (Figure 7 panel E). In conclusion, Sox2 over-expression is capable of converting non-tumorigenic human lung bronchial epithelial cells to a tumorigenic state, enabling them to grow as poorly differentiated squamous tumors in immunocompromised mice.

Bottom Line: Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2.In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth.These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.

View Article: PubMed Central - PubMed

Affiliation: Département Biologie du Cancer, Institut National de la Santé et de la Recherche Médicale, Institut de Génétique et de Biologie Moléculaire et Cellulaire, U964 Illkirch, France. hussenet@igbmc.fr

ABSTRACT
Squamous cell carcinoma (SCC) of the lung is a frequent and aggressive cancer type. Gene amplifications, a known activating mechanism of oncogenes, target the 3q26-qter region as one of the most frequently gained/amplified genomic sites in SCC of various types. Here, we used array comparative genomic hybridization to delineate the consensus region of 3q26.3 amplifications in lung SCC. Recurrent amplifications occur in 20% of lung SCC (136 tumors in total) and map to a core region of 2 Mb (Megabases) that encompasses SOX2, a transcription factor gene. Intense SOX2 immunostaining is frequent in nuclei of lung SCC, indicating potential active transcriptional regulation by SOX2. Analyses of the transcriptome of lung SCC, SOX2-overexpressing lung epithelial cells and embryonic stem cells (ESCs) reveal that SOX2 contributes to activate ESC-like phenotypes and provide clues pertaining to the deregulated genes involved in the malignant phenotype. In cell culture experiments, overexpression of SOX2 stimulates cellular migration and anchorage-independent growth while SOX2 knockdown impairs cell growth. Finally, SOX2 over-expression in non-tumorigenic human lung bronchial epithelial cells is tumorigenic in immunocompromised mice. These results indicate that the SOX2 transcription factor, a major regulator of stem cell function, is also an oncogene and a driver gene for the recurrent 3q26.33 amplifications in lung SCC.

Show MeSH
Related in: MedlinePlus