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Role of IL13RA2 in Sunitinib Resistance in Clear Cell Renal Cell Carcinoma.

Shibasaki N, Yamasaki T, Kanno T, Arakaki R, Sakamoto H, Utsunomiya N, Inoue T, Tsuruyama T, Nakamura E, Ogawa O, Kamba T - PLoS ONE (2015)

Bottom Line: Conversely, shRNA-mediated knockdown of IL13RA2 successfully overcame the sunitinib-resistance in Caki-1 cells.Histopathological analyses revealed that IL13RA2 repressed sunitinib-induced apoptosis without increasing tumor vasculature in vivo.To our knowledge, this is a novel mechanism of developing resistance to sunitinib in a certain population of ccRCC, and these results indicate that IL13RA2 could be one of potential target to overcome sunitinib resistance.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

ABSTRACT
Vascular endothelial growth factor (VEGF) and mammalian target of rapamycin are well-known therapeutic targets for renal cell carcinoma (RCC). Sunitinib is an agent that targets VEGF receptors and is considered to be a standard treatment for metastatic or unresectable clear cell RCC (ccRCC). However, ccRCC eventually develops resistance to sunitinib in most cases, and the mechanisms underlying this resistance are not fully elucidated. In the present study, we established unique primary xenograft models, KURC1 (Kyoto University Renal Cancer 1) and KURC2, from freshly isolated ccRCC specimens. The KURC1 xenograft initially responded to sunitinib treatment, however finally acquired resistance. KURC2 retained sensitivity to sunitinib for over 6 months. Comparing gene expression profiles between the two xenograft models with different sensitivity to sunitinib, we identified interleukin 13 receptor alpha 2 (IL13RA2) as a candidate molecule associated with the acquired sunitinib-resistance in ccRCC. And patients with high IL13RA2 expression in immunohistochemistry in primary ccRCC tumor tends to have sunitinib-resistant metastatic site. Next, we showed that sunitinib-sensitive 786-O cells acquired resistance in vivo when IL13RA2 was overexpressed. Conversely, shRNA-mediated knockdown of IL13RA2 successfully overcame the sunitinib-resistance in Caki-1 cells. Histopathological analyses revealed that IL13RA2 repressed sunitinib-induced apoptosis without increasing tumor vasculature in vivo. To our knowledge, this is a novel mechanism of developing resistance to sunitinib in a certain population of ccRCC, and these results indicate that IL13RA2 could be one of potential target to overcome sunitinib resistance.

No MeSH data available.


Related in: MedlinePlus

Evaluation of apoptosis and microvessel density after sunitinib treatment in our primary xenograft models.(A) ssDNA staining and (B) CD31 staining of KURC1 treated with sunitinib or vehicle with different sensitivity status. Scale bar, 50 μm. Apoptosis was assessed by calculating the ssDNA positivity rate, and MVD was determined from CD31 staining using Image J software. Statistical analysis was performed using the Students’ t-test (*P < 0.01).
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pone.0130980.g005: Evaluation of apoptosis and microvessel density after sunitinib treatment in our primary xenograft models.(A) ssDNA staining and (B) CD31 staining of KURC1 treated with sunitinib or vehicle with different sensitivity status. Scale bar, 50 μm. Apoptosis was assessed by calculating the ssDNA positivity rate, and MVD was determined from CD31 staining using Image J software. Statistical analysis was performed using the Students’ t-test (*P < 0.01).

Mentions: Finally, we examined if the inhibition of apoptosis regulated the sensitivity and development of sunitinib resistance in our primary xenograft model KURC1. We first examined the number of ssDNA-positive cells in both xenografts. Sunitinib treatment significantly increased the number of ssDNA-positive apoptotic cells in sunitinib-sensitive in KURC1 tumors at day 30. In contrast, in KURC1 sunitinib-resistant tumors at day 50, the number of apoptotic cells decreased to a level almost comparable to that of vehicle-treated cells at day 50 (Fig 5A). We next measured MVD in each xenograft. MVD was reduced after the treatment of sunitinib at day 30 or 50 in KURC1 xenograft tumors, irrespective of sunitinib sensitivity (Fig 5B). In order to estimate the total number of tumor vessels, MDV multiply the corresponding tumor volume. According to calculations, the ratio of number of vessels in control tumor at day 50, sensitive tumor at day 30, and resistant tumor at day 50 were 17, 1, and 3, respectively. Indeed, the ratio of them in p5 control tumor at day 50 and p5 resistant tumor at day 50 were estimated 2 and 1. These observations implicated total number of tumor vessels was slightly increased when tumors acquired sunitinib resistance despite of the reduction of MVD, although angiogenesis was still inhibited by sunitinib even in complete resistance state in our primary xenograft model. Collectively, these data suggested that IL13RA2-mediated resistance to sunitinib in ccRCC might be primarily caused by the inhibition of apoptosis.


Role of IL13RA2 in Sunitinib Resistance in Clear Cell Renal Cell Carcinoma.

Shibasaki N, Yamasaki T, Kanno T, Arakaki R, Sakamoto H, Utsunomiya N, Inoue T, Tsuruyama T, Nakamura E, Ogawa O, Kamba T - PLoS ONE (2015)

Evaluation of apoptosis and microvessel density after sunitinib treatment in our primary xenograft models.(A) ssDNA staining and (B) CD31 staining of KURC1 treated with sunitinib or vehicle with different sensitivity status. Scale bar, 50 μm. Apoptosis was assessed by calculating the ssDNA positivity rate, and MVD was determined from CD31 staining using Image J software. Statistical analysis was performed using the Students’ t-test (*P < 0.01).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482605&req=5

pone.0130980.g005: Evaluation of apoptosis and microvessel density after sunitinib treatment in our primary xenograft models.(A) ssDNA staining and (B) CD31 staining of KURC1 treated with sunitinib or vehicle with different sensitivity status. Scale bar, 50 μm. Apoptosis was assessed by calculating the ssDNA positivity rate, and MVD was determined from CD31 staining using Image J software. Statistical analysis was performed using the Students’ t-test (*P < 0.01).
Mentions: Finally, we examined if the inhibition of apoptosis regulated the sensitivity and development of sunitinib resistance in our primary xenograft model KURC1. We first examined the number of ssDNA-positive cells in both xenografts. Sunitinib treatment significantly increased the number of ssDNA-positive apoptotic cells in sunitinib-sensitive in KURC1 tumors at day 30. In contrast, in KURC1 sunitinib-resistant tumors at day 50, the number of apoptotic cells decreased to a level almost comparable to that of vehicle-treated cells at day 50 (Fig 5A). We next measured MVD in each xenograft. MVD was reduced after the treatment of sunitinib at day 30 or 50 in KURC1 xenograft tumors, irrespective of sunitinib sensitivity (Fig 5B). In order to estimate the total number of tumor vessels, MDV multiply the corresponding tumor volume. According to calculations, the ratio of number of vessels in control tumor at day 50, sensitive tumor at day 30, and resistant tumor at day 50 were 17, 1, and 3, respectively. Indeed, the ratio of them in p5 control tumor at day 50 and p5 resistant tumor at day 50 were estimated 2 and 1. These observations implicated total number of tumor vessels was slightly increased when tumors acquired sunitinib resistance despite of the reduction of MVD, although angiogenesis was still inhibited by sunitinib even in complete resistance state in our primary xenograft model. Collectively, these data suggested that IL13RA2-mediated resistance to sunitinib in ccRCC might be primarily caused by the inhibition of apoptosis.

Bottom Line: Conversely, shRNA-mediated knockdown of IL13RA2 successfully overcame the sunitinib-resistance in Caki-1 cells.Histopathological analyses revealed that IL13RA2 repressed sunitinib-induced apoptosis without increasing tumor vasculature in vivo.To our knowledge, this is a novel mechanism of developing resistance to sunitinib in a certain population of ccRCC, and these results indicate that IL13RA2 could be one of potential target to overcome sunitinib resistance.

View Article: PubMed Central - PubMed

Affiliation: Department of Urology, Graduate School of Medicine, Kyoto University, Kyoto, Japan.

ABSTRACT
Vascular endothelial growth factor (VEGF) and mammalian target of rapamycin are well-known therapeutic targets for renal cell carcinoma (RCC). Sunitinib is an agent that targets VEGF receptors and is considered to be a standard treatment for metastatic or unresectable clear cell RCC (ccRCC). However, ccRCC eventually develops resistance to sunitinib in most cases, and the mechanisms underlying this resistance are not fully elucidated. In the present study, we established unique primary xenograft models, KURC1 (Kyoto University Renal Cancer 1) and KURC2, from freshly isolated ccRCC specimens. The KURC1 xenograft initially responded to sunitinib treatment, however finally acquired resistance. KURC2 retained sensitivity to sunitinib for over 6 months. Comparing gene expression profiles between the two xenograft models with different sensitivity to sunitinib, we identified interleukin 13 receptor alpha 2 (IL13RA2) as a candidate molecule associated with the acquired sunitinib-resistance in ccRCC. And patients with high IL13RA2 expression in immunohistochemistry in primary ccRCC tumor tends to have sunitinib-resistant metastatic site. Next, we showed that sunitinib-sensitive 786-O cells acquired resistance in vivo when IL13RA2 was overexpressed. Conversely, shRNA-mediated knockdown of IL13RA2 successfully overcame the sunitinib-resistance in Caki-1 cells. Histopathological analyses revealed that IL13RA2 repressed sunitinib-induced apoptosis without increasing tumor vasculature in vivo. To our knowledge, this is a novel mechanism of developing resistance to sunitinib in a certain population of ccRCC, and these results indicate that IL13RA2 could be one of potential target to overcome sunitinib resistance.

No MeSH data available.


Related in: MedlinePlus