Long Non-Coding RNA SNHG6 Aggravates Pancreatic Cancer Through Upregulation of Far Upstream Element Binding Protein 1 by Sponging microRNA-26a-5p
Pancreatic cancer (PC) remains one of the deadliest malignancies, with a dismal 5-year survival rate primarily due to late diagnosis and limited therapeutic options. Recent research highlights the critical roles of non-coding RNAs, particularly long non-coding RNAs (lncRNAs), in cancer progression. This study investigates the oncogenic role of small nucleolar RNA host gene 6 (SNHG6) in PC, revealing its mechanism of action via interactions with microRNA-26a-5p (miR-26a-5p) and far upstream element binding protein 1 (FUBP1).
SNHG6 Is Overexpressed in Pancreatic Cancer
The study began by analyzing SNHG6 expression in clinical samples and cell lines. Bioinformatics analysis using the StarBase database revealed elevated SNHG6 levels in PC tissues compared to adjacent normal tissues (Figure 1A). Experimental validation confirmed these findings: SNHG6 expression was significantly higher in tumor tissues than in normal tissues (1.56 ± 0.06 vs. 1.00 ± 0.05, t = 16.03, P < 0.001; Figure 1B). Similarly, among four PC cell lines (MIAPaCa-2, BxPC-3, Capan-1, and Panc-1), SNHG6 expression was highest in Panc-1 cells (3.87 ± 0.13 vs. 1.00 ± 0.06 in normal HPDE6-C7 cells, t = 34.72, P < 0.001) and lowest in MIAPaCa-2 cells (1.41 ± 0.07 vs. 1.00 ± 0.06, t = 7.70, P = 0.0015; Figure 1C). These results positioned SNHG6 as a potential driver of PC pathogenesis.
Silencing SNHG6 Inhibits Cancer Cell Aggressiveness
Functional studies demonstrated the oncogenic role of SNHG6. In Panc-1 cells, siRNA-mediated SNHG6 knockdown (si-SNHG6) reduced SNHG6 expression by 78% (0.21 ± 0.06 vs. 0.97 ± 0.05 in the negative control, t = 16.85, P < 0.001; Figure 2A). This suppression significantly impaired epithelial-mesenchymal transition (EMT), as evidenced by decreased N-cadherin (0.41 ± 0.04 vs. 0.74 ± 0.05, t = 8.93), Vimentin (0.25 ± 0.03 vs. 0.55 ± 0.04, t = 10.39), and β-catenin (0.32 ± 0.03 vs. 0.62 ± 0.05, t = 8.91), alongside increased E-cadherin (1.36 ± 0.07 vs. 0.65 ± 0.06, t = 13.34; all P < 0.001; Figure 2B). Proliferation assays showed time-dependent growth inhibition post-SNHG6 silencing (Figure 2C), while colony formation rates dropped sharply (Figure 2D). Flow cytometry and Hoechst staining revealed increased apoptosis (Figure 2E–F), and Transwell assays confirmed reduced migration and invasion (Figure 2G). Conversely, SNHG6 overexpression in MIAPaCa-2 cells reversed these effects, promoting proliferation, migration, and EMT.
SNHG6 Sponges miR-26a-5p to Upregulate FUBP1
Mechanistic studies uncovered a regulatory axis involving SNHG6, miR-26a-5p, and FUBP1. Bioinformatics tools (StarBase, TargetScan) predicted binding sites between SNHG6 and miR-26a-5p (Figure 3A) and between miR-26a-5p and the 3′ untranslated region (UTR) of FUBP1 (Figure 3E). Experimental validation confirmed these interactions:
- SNHG6-miR-26a-5p Interaction: In Panc-1 cells, SNHG6 knockdown increased miR-26a-5p levels, while SNHG6 overexpression reduced them (P < 0.01; Figure 3B). Dual-luciferase assays showed that miR-26a-5p mimic reduced luciferase activity in SNHG6 wild-type (WT) but not mutant (MUT) constructs (P < 0.01; Figure 3C). RNA pull-down assays confirmed direct binding (Figure 3D).
- miR-26a-5p-FUBP1 Interaction: miR-26a-5p overexpression in MIAPaCa-2 cells decreased FUBP1 mRNA (0.33 ± 0.05 vs. 1.00 ± 0.08, t = 11.09, P < 0.001; Figure 3F) and protein levels (0.30 ± 0.04 vs. 0.91 ± 0.07, t = 13.02, P < 0.001; Figure 3G). Dual-luciferase assays confirmed miR-26a-5p binding to the FUBP1 3'UTR (P < 0.01; Figure 3H).
- SNHG6-FUBP1 Regulation: SNHG6 silencing in Panc-1 cells reduced FUBP1 expression (mRNA: 0.39 ± 0.06 vs. 1.00 ± 0.09, t = 9.74; protein: 0.31 ± 0.04 vs. 0.95 ± 0.06, t = 16.07; both P < 0.001; Figure 3I–J), demonstrating that SNHG6 elevates FUBP1 by sequestering miR-26a-5p.
Rescue Experiments Confirm the Mechanism
Co-transfection experiments in MIAPaCa-2 cells validated the regulatory pathway. SNHG6 overexpression reduced miR-26a-5p levels (0.32 ± 0.05 vs. 1.00 ± 0.08, t = 12.67, P < 0.001; Figure 4A), enhancing proliferation, colony formation, migration, and invasion while suppressing apoptosis (Figure 4B–F). However, miR-26a-5p mimic co-transfection counteracted these effects, restoring miR-26a-5p levels (0.98 ± 0.07 vs. 0.32 ± 0.05, t = 13.92, P < 0.001) and reversing SNHG6-driven malignancy. This confirmed that SNHG6 exacerbates PC progression via miR-26a-5p sponging and subsequent FUBP1 upregulation.
In Vivo Tumor Suppression by SNHG6 Silencing
In nude mouse xenografts, SNHG6 knockdown (si-SNHG6) significantly inhibited tumor growth. Tumors in the si-SNHG6 group were smaller (Figure 5C) and lighter (0.43 ± 0.05 g vs. 0.89 ± 0.08 g, t = 8.16, P < 0.001; Figure 5E) compared to controls. SNHG6 and FUBP1 expression in tumors was reduced (SNHG6: 0.24 ± 0.06 vs. 1.00 ± 0.09, t = 11.55; FUBP1 mRNA: 0.28 ± 0.04 vs. 1.00 ± 0.07, t = 15.74; protein: 0.26 ± 0.03 vs. 0.98 ± 0.05, t = 20.95; all P < 0.001), while miR-26a-5p was upregulated (3.72 ± 0.35 vs. 1.00 ± 0.08, t = 12.31, P < 0.001; Figure 5A–B). These results underscore the therapeutic potential of targeting SNHG6.
Conclusion
This study elucidates a novel SNHG6/miR-26a-5p/FUBP1 axis in PC progression. SNHG6 acts as a competing endogenous RNA (ceRNA), sponging miR-26a-5p to derepress FUBP1, thereby driving EMT, proliferation, and metastasis. Silencing SNHG6 or restoring miR-26a-5p activity suppresses tumor growth in vitro and in vivo, offering promising therapeutic strategies. These findings align with previous studies linking SNHG6 to other cancers and highlight its role as a prognostic marker and therapeutic target in PC.
doi.org/10.1097/CM9.0000000000000758
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