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The anti-apoptotic BAG3 protein is expressed in lung carcinomas and regulates small cell lung carcinoma (SCLC) tumor growth.

Chiappetta G, Basile A, Barbieri A, Falco A, Rosati A, Festa M, Pasquinelli R, Califano D, Palma G, Costanzo R, Barcaroli D, Capunzo M, Franco R, Rocco G, Pascale M, Turco MC, De Laurenzi V, Arra C - Oncotarget (2014)

Bottom Line: Normal lung tissue did not express BAG3 while we detected the expression of BAG3 by immunohistochemistry in all the 13 squamous cell carcinomas, 13 adenocarcinomas and 4 large cell carcinomas.Treatment with bag3 siRNA-Ad significantly reduced tumor growth and improved animal survival.In conclusion we show that a subset of SCLCs over express BAG3 that exerts an anti-apoptotic effect resulting in resistance to chemotherapy.

View Article: PubMed Central - PubMed

Affiliation: Functional Genomic Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori "Fondazione Giovanni Pascale", IRCCS, Naples, Italy. .

ABSTRACT
BAG3, member the HSP70 co-chaperones family, has been shown to play a relevant role in the survival, growth and invasiveness of different tumor types. In this study, we investigate the expression of BAG3 in 66 specimens from different lung tumors and the role of this protein in small cell lung cancer (SCLC) tumor growth. Normal lung tissue did not express BAG3 while we detected the expression of BAG3 by immunohistochemistry in all the 13 squamous cell carcinomas, 13 adenocarcinomas and 4 large cell carcinomas. Furthermore, we detected BAG3 expression in 22 of the 36 SCLCs analyzed. The role on SCLC cell survival was determined by down-regulating BAG3 levels in two human SCLC cell lines, i.e. H69 and H446, in vitro and measuring cisplatin induced apoptosis. Indeed down-regulation of BAG3 determines increased cell death and sensitizes cells to cisplatin treatment. The effect of BAG3 down-regulation on tumor growth was also investigated in an in vivo xenograft model by treating mice with an adenovirus expressing a specific bag3 siRNA. Treatment with bag3 siRNA-Ad significantly reduced tumor growth and improved animal survival. In conclusion we show that a subset of SCLCs over express BAG3 that exerts an anti-apoptotic effect resulting in resistance to chemotherapy.

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Analysis of BAG3 expression in H69 xenograftsA) Western blot analysis of protein extracted from H69 xenografts treated with PBS 100 μl (untreated), scr siRNA-Ad (108 pfu/100μl) or bag3 siRNA-Ad (108 pfu/100μl) by intratumoral injection, twice a week. B) Immunohistochemistry with anti-BAG3 monoclonal of xenograft tumors treated as in A (200x). Negative control: immunostaining of xenografted tumor samples stained without the primary antibody (200x).
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Figure 5: Analysis of BAG3 expression in H69 xenograftsA) Western blot analysis of protein extracted from H69 xenografts treated with PBS 100 μl (untreated), scr siRNA-Ad (108 pfu/100μl) or bag3 siRNA-Ad (108 pfu/100μl) by intratumoral injection, twice a week. B) Immunohistochemistry with anti-BAG3 monoclonal of xenograft tumors treated as in A (200x). Negative control: immunostaining of xenografted tumor samples stained without the primary antibody (200x).

Mentions: Since in vitro data showed that down-regulation of BAG3 induces apoptosis in SCLS cells, we investigated the effects of bag3 siRNA-Ad treatment on tumor growth and apoptosis in vivo. As shown in Fig. 4A, we observed that intra-tumoral injection of bag3 siRNA-Ad was able to reduce in vivo tumor growth after 44 days of treatment as compared to the scramble-treated (scr siRNA-Ad) and control groups (p<0.001). Accordingly, mice treated with bag3 siRNA-Ad survived longer than control (PBS) and scr siRNA-Ad-treated mice (p<0.05) (Fig. 4B). Western blot and immunohistochemical analysis of tumor samples from xenografts treated for 12 days with bag3 siRNA-Ad specifically confirm a reduction of BAG3 protein levels (Fig. 5 A, B).


The anti-apoptotic BAG3 protein is expressed in lung carcinomas and regulates small cell lung carcinoma (SCLC) tumor growth.

Chiappetta G, Basile A, Barbieri A, Falco A, Rosati A, Festa M, Pasquinelli R, Califano D, Palma G, Costanzo R, Barcaroli D, Capunzo M, Franco R, Rocco G, Pascale M, Turco MC, De Laurenzi V, Arra C - Oncotarget (2014)

Analysis of BAG3 expression in H69 xenograftsA) Western blot analysis of protein extracted from H69 xenografts treated with PBS 100 μl (untreated), scr siRNA-Ad (108 pfu/100μl) or bag3 siRNA-Ad (108 pfu/100μl) by intratumoral injection, twice a week. B) Immunohistochemistry with anti-BAG3 monoclonal of xenograft tumors treated as in A (200x). Negative control: immunostaining of xenografted tumor samples stained without the primary antibody (200x).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4196167&req=5

Figure 5: Analysis of BAG3 expression in H69 xenograftsA) Western blot analysis of protein extracted from H69 xenografts treated with PBS 100 μl (untreated), scr siRNA-Ad (108 pfu/100μl) or bag3 siRNA-Ad (108 pfu/100μl) by intratumoral injection, twice a week. B) Immunohistochemistry with anti-BAG3 monoclonal of xenograft tumors treated as in A (200x). Negative control: immunostaining of xenografted tumor samples stained without the primary antibody (200x).
Mentions: Since in vitro data showed that down-regulation of BAG3 induces apoptosis in SCLS cells, we investigated the effects of bag3 siRNA-Ad treatment on tumor growth and apoptosis in vivo. As shown in Fig. 4A, we observed that intra-tumoral injection of bag3 siRNA-Ad was able to reduce in vivo tumor growth after 44 days of treatment as compared to the scramble-treated (scr siRNA-Ad) and control groups (p<0.001). Accordingly, mice treated with bag3 siRNA-Ad survived longer than control (PBS) and scr siRNA-Ad-treated mice (p<0.05) (Fig. 4B). Western blot and immunohistochemical analysis of tumor samples from xenografts treated for 12 days with bag3 siRNA-Ad specifically confirm a reduction of BAG3 protein levels (Fig. 5 A, B).

Bottom Line: Normal lung tissue did not express BAG3 while we detected the expression of BAG3 by immunohistochemistry in all the 13 squamous cell carcinomas, 13 adenocarcinomas and 4 large cell carcinomas.Treatment with bag3 siRNA-Ad significantly reduced tumor growth and improved animal survival.In conclusion we show that a subset of SCLCs over express BAG3 that exerts an anti-apoptotic effect resulting in resistance to chemotherapy.

View Article: PubMed Central - PubMed

Affiliation: Functional Genomic Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori "Fondazione Giovanni Pascale", IRCCS, Naples, Italy. .

ABSTRACT
BAG3, member the HSP70 co-chaperones family, has been shown to play a relevant role in the survival, growth and invasiveness of different tumor types. In this study, we investigate the expression of BAG3 in 66 specimens from different lung tumors and the role of this protein in small cell lung cancer (SCLC) tumor growth. Normal lung tissue did not express BAG3 while we detected the expression of BAG3 by immunohistochemistry in all the 13 squamous cell carcinomas, 13 adenocarcinomas and 4 large cell carcinomas. Furthermore, we detected BAG3 expression in 22 of the 36 SCLCs analyzed. The role on SCLC cell survival was determined by down-regulating BAG3 levels in two human SCLC cell lines, i.e. H69 and H446, in vitro and measuring cisplatin induced apoptosis. Indeed down-regulation of BAG3 determines increased cell death and sensitizes cells to cisplatin treatment. The effect of BAG3 down-regulation on tumor growth was also investigated in an in vivo xenograft model by treating mice with an adenovirus expressing a specific bag3 siRNA. Treatment with bag3 siRNA-Ad significantly reduced tumor growth and improved animal survival. In conclusion we show that a subset of SCLCs over express BAG3 that exerts an anti-apoptotic effect resulting in resistance to chemotherapy.

Show MeSH
Related in: MedlinePlus