Elevated expression of SATB1 is involved in pancreatic tumorigenesis and is associated with poor patient survival

Abstract

Special AT‑rich sequence‑binding protein 1 (SATB1) is a master chromatin organizer which has been reported to be implicated in tumor progression in breast and lung cancer. However, its functions in pancreatic tumorigenesis have yet to be elucidated. In the present study, the involvement of SATB1 in pancreatic cancer development was investigated in human BxPC‑3 pancreatic adenocarcinoma cells. Short hairpin (sh)RNA was used to stably downregulate SATB1 expression, and functional assays, including cell proliferation, colony formation, soft agar and migration assays, were performed in vitro. In addition, a mouse pancreatic cancer xenograft model was created to examine the tumor‑promoting properties of SATB1 in vivo. The present findings demonstrated that stable knockdown of SATB1 expression inhibited the proliferation, colony formation, anchorage‑independent growth and suppressed the migratory capabilities of BxPC‑3 cells in vitro. In addition, SATB1 downregulation significantly inhibited tumor growth in xenografted mice in vivo. Furthermore, SATB1 was revealed to be upregulated in human pancreatic cancer tissue samples compared with matched non‑cancerous adjacent tissues, and high SATB1 expression was associated with poor patient survival. Overall, the present study demonstrated that SATB1 promoted the proliferation of pancreatic cancer cells in vitro. In addition, SATB1 expression was revealed to be upregulated in human pancreatic cancer tissues and its upregulation was associated with poor patient survival. Therefore, SATB1 may have potential as a novel prognostic biomarker and therapeutic target for the treatment of patients with pancreatic cancer.

Figure 1.

Downregulation of SATB1 expression using shRNAs in human BxPC-3 pancreatic adenocarcinoma cells. (A) Silencing of SATB1 expression in BxPC-3 cells using 2 independent shRNAs targeting SATB1 was confirmed using western blot analysis. (B) Blots were semi-quantified using densitometry. Control cells were transduced with control shRNA. Data are expressed as the mean ± standard deviation. **P<0.01 vs. Control. SATB, special AT-rich sequence-binding protein; sh, short hairpin.

Figure 2.

Downregulation of SATB1 expression suppresses the proliferation and clonogenicity of human BxPC-3 pancreatic adenocarcinoma cells. (A) Growth curves of BxPC-3 cells stably expressing control or SATB1-targeting shRNAs. (B) Colony formation capabilities of BxPC-3 cells stably expressing control or SATB1-targeting shRNAs. Data are expressed as the mean ± standard deviation. *P<0.05 vs. Control. SATB, special AT-rich sequence-binding protein; sh, short hairpin.

Figure 3.

Downregulation of SATB1 expression suppresses the anchorage-independent growth and invasion of human BxPC-3 pancreatic adenocarcinoma cells. (A) A soft agar growth assay detected the anchorage-independent growth of BxPC-3 cells stably expressing control or SATB1-targeting shRNAs. (B) A Matrigel invasion assay assessed the invasive capabilities of BxPC-3 cells stably expressing control or SATB1-targeting shRNAs. Data are expressed as the mean ± standard deviation. ^•••P<0.001, ****P<0.0001 vs. Control. SATB, special AT-rich sequence-binding protein; sh, short hairpin.

Figure 4.

Downregulation of SATB1 expression inhibits tumor growth in a mouse xenograft model. (A) Weight and representative images of the xenograft tumors isolated from mice implanted with human BxPC-3 pancreatic adenocarcinoma cells stably expressing control or SATB1-targeting shRNA-1. (B) Growth curves of tumor xenografts isolated from mice implanted with human BxPC-3 pancreatic adenocarcinoma cells stably expressing control or SATB1-targeting shRNA-1 (n=5 mice/group). Data are expressed as the mean ± standard deviation. *P<0.05, **P<0.01, ****P<0.0001 vs. Control. SATB, special AT-rich sequence-binding protein; sh, short hairpin.

Figure 5.

SATB1 expression is upregulated in tumor tissue samples isolated from patients with pancreatic cancer, and is associated with poor survival. (A) SATB1 mRNA expression was assessed in tumor and adjacent non-cancerous tissue samples isolated from 48 patients with pancreatic cancer. Dots represent the mRNA expression level of SATB1 for each patient. (B) Representative immunohistochemical staining of pancreatic cancer and adjacent non-cancerous tissue samples. Magnification, ×200. (C) Overall survival in patients with pancreatic cancer with low or high levels of SATB1 expression. Survival curves were constructed using Kaplan-Mier analysis and statistical analysis was performed using the log-rank test. ****P<0.0001. SATB, special AT-rich sequence-binding protein.