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LIN28B is highly expressed in atypical teratoid/rhabdoid tumor (AT/RT) and suppressed through the restoration of SMARCB1.

Choi SA, Kim SK, Lee JY, Wang KC, Lee C, Phi JH - Cancer Cell Int. (2016)

Bottom Line: The knockdown of LIN28B decreased cell viability and proliferation, induced cell cycle arrest, and reduced migration in primary cultured AT/RT cells.The restoration of SMARCB1 in AT/RT cells decreased the expression of LIN28B and CCND1.These results show that LIN28B might be regulated through SMARCB1; the loss of SMARCB1 protein in AT/RT results in the unopposed expression of LIN28B and related oncogenes such as CCND1, leading to tumorigenesis.

View Article: PubMed Central - PubMed

Affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, 101 Daehakro, Jongno-gu, Seoul, 03080 Republic of Korea.

ABSTRACT

Background: Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant brain tumor that almost exclusively develops in young children. AT/RT belongs to the embryonal brain tumor group, comprising primitive tumors recapitulating the early development of the central nervous system during embryogenesis. The loss of SMARCB1 protein expression is a hallmark of AT/RT pathogenesis. LIN28A/B is a key gene in embryonic development and for the maintenance of pluripotency in stem cells. LIN28B might be an important co-player in AT/RT pathogenesis, considering the primitive nature and young age onset of AT/RT.

Methods: We explored the expression patterns of LIN28B in AT/RT and compared it with the expression in cortical dysplasia and medulloblastoma. The functional role of LIN28B was assessed using LIN28B-siRNAs in primary cultured AT/RT cells.

Results: LIN28B is highly expressed in AT/RT compared with medulloblastoma and other embryonal tumors, whereas primary let-7g miRNA is down-regulated. AT/RT also showed higher expression of CCND1 and MYC, and lower expression of CDKN1C. The suppression of CCND1 expression and enhanced expression of CDKN1C were also observed. The knockdown of LIN28B decreased cell viability and proliferation, induced cell cycle arrest, and reduced migration in primary cultured AT/RT cells. Furthermore, we showed that the knockdown of LIN28B decreased the expression of other pluripotency-related genes (OCT4 and NANOG) and the mesenchymal-epithelial transition signature. We also transfected wild-type SMARCB1 into primary cultured AT/RT cells. The restoration of SMARCB1 in AT/RT cells decreased the expression of LIN28B and CCND1.

Conclusions: These results show that LIN28B might be regulated through SMARCB1; the loss of SMARCB1 protein in AT/RT results in the unopposed expression of LIN28B and related oncogenes such as CCND1, leading to tumorigenesis. Therefore, the strategic role of LIN28B in AT/RT might be utilized as an important therapeutic target.

No MeSH data available.


Related in: MedlinePlus

Overexpression of SMARCB1in AT/RT, MB and glioblastoma cells. a Transfection efficiency of SMARCB1 was confirmed using RT-qPCR at 48 h after pEGFP-C2.SMARCB1 transfection. b Transfection with pEGFP-C2.SMARCB1 decreased LIN28B and CCND1 expression and increased CDKN1C expression. c Cell viability was significantly diminished after the introduction of SMARCB1. d LIN28B was suppressed and OCT4 was increased after the restoration of SMARCB1 expression in all AT/RT cells. However, the differential expression of LIN28A, SOX2, KLF4 and MYC was detected in all AT/RT cells. e In MB and glioblastoma, the expression of LIN28B, CCND1 and CDKN1C was unchanged after SMARCB1 knockdown. **P < 0.01; ***P < 0.001. Error bars represent ±SD
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Fig6: Overexpression of SMARCB1in AT/RT, MB and glioblastoma cells. a Transfection efficiency of SMARCB1 was confirmed using RT-qPCR at 48 h after pEGFP-C2.SMARCB1 transfection. b Transfection with pEGFP-C2.SMARCB1 decreased LIN28B and CCND1 expression and increased CDKN1C expression. c Cell viability was significantly diminished after the introduction of SMARCB1. d LIN28B was suppressed and OCT4 was increased after the restoration of SMARCB1 expression in all AT/RT cells. However, the differential expression of LIN28A, SOX2, KLF4 and MYC was detected in all AT/RT cells. e In MB and glioblastoma, the expression of LIN28B, CCND1 and CDKN1C was unchanged after SMARCB1 knockdown. **P < 0.01; ***P < 0.001. Error bars represent ±SD

Mentions: To determine whether SMARCB1 regulates LIN28B expression, we transfected pEGFP-C2.SMARCB1 into primary cultured AT/RT cells (Fig. 6a). Subsequently, we performed an immunoblot analysis of LIN28B, CCND1 and CDKN1C.The decreased expression of LIN28B and CCND1 and increased expression of CDKN1C were observed (Fig. 6b). Transfection of pEGFP-C2.SMARCB1 reduced cell viability (pEGFP-C2 vs. pEGFP-C2.SMARCB1: 100 ± 2.1 vs. 43.8 ± 2.3 % in SNU-AT/RT3, p = 0.0019; 100 ± 14.4 vs. 8.1 ± 1.5 % in SNU-AT/RT4, p < 0.001; Fig. 6c). We further investigated the expression of pluripotency-related genes using RT-qPCR in 2 AT/RT cell lines and observed different expression levels of the genes. SMARCB1 expression significantly suppressed LIN28B gene expression in AT/RT cells (Fig. 6d). In SNU-AT/RT3 cells, KLF4 and OCT4 expression were increased, but the expression of LIN28A, SOX2 and MYC remained unchanged (Fig. 6d). In SNU-AT/RT-4 cells, LIN28A and OCT4 were increased, but SOX2, KLF4 and MYC expression was decreased (Fig. 6d). Interestingly, only OCT4 was elevated in both AT/RT cell lines.Fig. 6


LIN28B is highly expressed in atypical teratoid/rhabdoid tumor (AT/RT) and suppressed through the restoration of SMARCB1.

Choi SA, Kim SK, Lee JY, Wang KC, Lee C, Phi JH - Cancer Cell Int. (2016)

Overexpression of SMARCB1in AT/RT, MB and glioblastoma cells. a Transfection efficiency of SMARCB1 was confirmed using RT-qPCR at 48 h after pEGFP-C2.SMARCB1 transfection. b Transfection with pEGFP-C2.SMARCB1 decreased LIN28B and CCND1 expression and increased CDKN1C expression. c Cell viability was significantly diminished after the introduction of SMARCB1. d LIN28B was suppressed and OCT4 was increased after the restoration of SMARCB1 expression in all AT/RT cells. However, the differential expression of LIN28A, SOX2, KLF4 and MYC was detected in all AT/RT cells. e In MB and glioblastoma, the expression of LIN28B, CCND1 and CDKN1C was unchanged after SMARCB1 knockdown. **P < 0.01; ***P < 0.001. Error bars represent ±SD
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Fig6: Overexpression of SMARCB1in AT/RT, MB and glioblastoma cells. a Transfection efficiency of SMARCB1 was confirmed using RT-qPCR at 48 h after pEGFP-C2.SMARCB1 transfection. b Transfection with pEGFP-C2.SMARCB1 decreased LIN28B and CCND1 expression and increased CDKN1C expression. c Cell viability was significantly diminished after the introduction of SMARCB1. d LIN28B was suppressed and OCT4 was increased after the restoration of SMARCB1 expression in all AT/RT cells. However, the differential expression of LIN28A, SOX2, KLF4 and MYC was detected in all AT/RT cells. e In MB and glioblastoma, the expression of LIN28B, CCND1 and CDKN1C was unchanged after SMARCB1 knockdown. **P < 0.01; ***P < 0.001. Error bars represent ±SD
Mentions: To determine whether SMARCB1 regulates LIN28B expression, we transfected pEGFP-C2.SMARCB1 into primary cultured AT/RT cells (Fig. 6a). Subsequently, we performed an immunoblot analysis of LIN28B, CCND1 and CDKN1C.The decreased expression of LIN28B and CCND1 and increased expression of CDKN1C were observed (Fig. 6b). Transfection of pEGFP-C2.SMARCB1 reduced cell viability (pEGFP-C2 vs. pEGFP-C2.SMARCB1: 100 ± 2.1 vs. 43.8 ± 2.3 % in SNU-AT/RT3, p = 0.0019; 100 ± 14.4 vs. 8.1 ± 1.5 % in SNU-AT/RT4, p < 0.001; Fig. 6c). We further investigated the expression of pluripotency-related genes using RT-qPCR in 2 AT/RT cell lines and observed different expression levels of the genes. SMARCB1 expression significantly suppressed LIN28B gene expression in AT/RT cells (Fig. 6d). In SNU-AT/RT3 cells, KLF4 and OCT4 expression were increased, but the expression of LIN28A, SOX2 and MYC remained unchanged (Fig. 6d). In SNU-AT/RT-4 cells, LIN28A and OCT4 were increased, but SOX2, KLF4 and MYC expression was decreased (Fig. 6d). Interestingly, only OCT4 was elevated in both AT/RT cell lines.Fig. 6

Bottom Line: The knockdown of LIN28B decreased cell viability and proliferation, induced cell cycle arrest, and reduced migration in primary cultured AT/RT cells.The restoration of SMARCB1 in AT/RT cells decreased the expression of LIN28B and CCND1.These results show that LIN28B might be regulated through SMARCB1; the loss of SMARCB1 protein in AT/RT results in the unopposed expression of LIN28B and related oncogenes such as CCND1, leading to tumorigenesis.

View Article: PubMed Central - PubMed

Affiliation: Division of Pediatric Neurosurgery, Seoul National University Children's Hospital, 101 Daehakro, Jongno-gu, Seoul, 03080 Republic of Korea.

ABSTRACT

Background: Atypical teratoid/rhabdoid tumor (AT/RT) is a highly malignant brain tumor that almost exclusively develops in young children. AT/RT belongs to the embryonal brain tumor group, comprising primitive tumors recapitulating the early development of the central nervous system during embryogenesis. The loss of SMARCB1 protein expression is a hallmark of AT/RT pathogenesis. LIN28A/B is a key gene in embryonic development and for the maintenance of pluripotency in stem cells. LIN28B might be an important co-player in AT/RT pathogenesis, considering the primitive nature and young age onset of AT/RT.

Methods: We explored the expression patterns of LIN28B in AT/RT and compared it with the expression in cortical dysplasia and medulloblastoma. The functional role of LIN28B was assessed using LIN28B-siRNAs in primary cultured AT/RT cells.

Results: LIN28B is highly expressed in AT/RT compared with medulloblastoma and other embryonal tumors, whereas primary let-7g miRNA is down-regulated. AT/RT also showed higher expression of CCND1 and MYC, and lower expression of CDKN1C. The suppression of CCND1 expression and enhanced expression of CDKN1C were also observed. The knockdown of LIN28B decreased cell viability and proliferation, induced cell cycle arrest, and reduced migration in primary cultured AT/RT cells. Furthermore, we showed that the knockdown of LIN28B decreased the expression of other pluripotency-related genes (OCT4 and NANOG) and the mesenchymal-epithelial transition signature. We also transfected wild-type SMARCB1 into primary cultured AT/RT cells. The restoration of SMARCB1 in AT/RT cells decreased the expression of LIN28B and CCND1.

Conclusions: These results show that LIN28B might be regulated through SMARCB1; the loss of SMARCB1 protein in AT/RT results in the unopposed expression of LIN28B and related oncogenes such as CCND1, leading to tumorigenesis. Therefore, the strategic role of LIN28B in AT/RT might be utilized as an important therapeutic target.

No MeSH data available.


Related in: MedlinePlus