Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 11 (9)

6'-Sialyllactose Ameliorates In Vivo and In Vitro Benign Prostatic Hyperplasia by Regulating the E2F1/pRb-AR Pathway

Affiliations

6'-Sialyllactose Ameliorates In Vivo and In Vitro Benign Prostatic Hyperplasia by Regulating the E2F1/pRb-AR Pathway

Bo-Ram Jin et al. Nutrients.

Abstract

Background: 6'-Sialyllactose (6SL) displays a wide range of the bioactive benefits, such as anti-proliferative and anti-angiogenic activities. However, the therapeutic effects of 6SL on benign prostatic hyperplasia (BPH) remain unknown.

Methods: Six-week-old male Wistar rats (n = 40) were used for in vivo experiments. All rats were castrated and experimental BPH was induced in castrated rats by intramuscular injection of testosterone, with the exception of those in the control group. Rats with BPH were administrated finasteride and 0.5 or 1.0 mg/kg 6SL. Furthermore, the inhibitory effects of 6SL on human epithelial BPH cell line (BPH-1) cells were determined in vitro.

Results: Rats with BPH exhibited outstanding BPH manifestations, including prostate enlargement, histological alterations, and increased prostate-specific antigen (PSA) levels. Compared to those in the BPH group, rats in the 6SL group showed fewer pathological changes and normal androgen events, followed by restoration of retinoblastoma protein (pRb) and cell cycle-related proteins. In BPH-1 cells, treatment with 6SL significantly suppressed the effects on the androgen receptor (AR), PSA, and E2F transcription factor 1 (E2F1)-dependent cell cycle protein expression.

Conclusions: 6SL demonstrated anti-proliferative effects in a testosterone-induced BPH rat model and on BPH-1 cells by regulating the pRB/E2F1-AR pathway. According to our results, we suggest that 6SL may be considered a potential agent for the treatment of BPH.

Keywords: 6′-Sialyllactose (6SL); BPH-1; E2F1; androgen receptor (AR); benign prostatic hyperplasia (BPH); pRB; testosterone-induced BPH rat model.

Conflict of interest statement

The authors declare no competing financial or non-financial interests.

Figures

Figure 1
Figure 1
Effect of 6SL on enlarged prostate in a testosterone propionate (TP)-induced benign prostatic hyperplasia (BPH) rat model. (A) Representative images showing changes of prostatic tissues from each experimental group are detected. (B) Prostate weight (PW) and (C) prostate weight to body weight (PW/BW) ratio was measured and analyzed. Prostate weight to body weight (PW/BW) ratio = (Mean value of prostate weight from the experimental group / Mean value of body weight from the experimental group) × 1000. All data are mean ± SD (n = 8 per group). (D) The concentration of DHT was analyzed using ELISA kit. All data are mean ± SD (n = 4). Values with different letters indicate significant differences, p < 0.05. Con; control animals, BPH; rats with BPH induction, Fina; rats with BPH orally administrated 5 mg/kg finasteride, 6SL 0.5 and 1.0; rats with BPH intraperitoneally administrated 0.5 or 1.0 mg/kg 6SL.
Figure 2
Figure 2
Effect of 6SL on histological change and androgen-relative protein expression in TP-induced BPH rat model. (A) Prostatic tissue slides were stained by hematoxylin and eosin (H&E) and observed (magnification × 100). (B) Thickness of epithelium tissue from prostate (TETP) was measured and expressed as the mean ± SD of five rats per experimental group. (C) The protein expressions of androgen receptor (AR), prostate-specific antigen (PSA), and proliferating cell nuclear antigen (PCNA) in prostatic tissues were determined by immunoblotting. The densities of protein were calculated using ImageJ Software and the relative protein level was normalized to internal control β-actin. Values with different letters indicate significant differences, p < 0.05.
Figure 3
Figure 3
Effect of 6SL on E2F transcription factor 1 (E2F1)-relative and cell cycle protein expression in TP-induced BPH rat model. (A) The manifestation of retinoblastoma protein (pRb) in prostatic tissues from rats was shown by immunohistochemistry. The immunoblotting images and quantitative analysis show the protein expression of (B) pRb, E2F1, and (C) cyclin A, cdk2, cyclin D1, Cdk4. The densities of proteins were calculated using ImageJ Software. Relative protein level represents densitometric values of each protein as ratio to β-actin. Values with different letters indicate significant differences, p < 0.05.
Figure 4
Figure 4
The inhibitory effect of 6SL on BPH cell line (BPH-1) cells’ growth and androgen-relative protein expression. (A) BPH-1 cells were treated with various concentration of 6SL for 24 h to assay cell viability. (B) AR and PSA protein expression were determined by immunoblotting and relative protein level was analyzed. β-actin was used as an internal control gene. The densities of protein were calculated using ImageJ Software. Values of three separate experiments are represented as mean ± SD. Different letters indicate significant differences, p < 0.05. DMSO; Dimethyl sulfoxide.
Figure 5
Figure 5
The depressant effect of 6SL on E2F1-dependent cell cycle protein expression in BPH-1 cells. (A) pRb, E2F1, and (B) Cyclin A, Cdk2, Cyclin D1 protein levels were analyzed by immunoblotting. The densities of proteins were calculated using ImageJ Software. Relative protein level was normalized to β-actin and values of three separate experiments are represented as mean ± SD. Different letters indicate significant differences, p < 0.05.
Figure 6
Figure 6
Proposed action mechanism of 6SL in TP-induced BPH rats and BPH-1 cells. 6SL demonstrated anti-proliferative effects in a testosterone-induced BPH rat model and on BPH-1 cells by regulating the pRB/E2F1–AR pathway. 6SL inhibited prostate enlargement via controlling androgen/AR signaling-dependent hyperproliferation. AR influences E2F-regulated transcription that plays a paramount role in cell cycle progression and apoptosis signaling. Here, inhibition of E2F1/pRb and cell cycle progression by 6SL may be attributed to its anti-proliferative properties, supporting its regulation of the pRB/E2F1–AR network.

Similar articles

See all similar articles

References

    1. Bode L. Recent advances on structure, metabolism, and function of human milk oligosaccharides. J. Nutr. 2006;136:2127–2130. doi: 10.1093/jn/136.8.2127. - DOI - PubMed
    1. Bode L., Kunz C., Muhly-Reinholz M., Mayer K., Seeger W., Rudloff S. Inhibition of monocyte, lymphocyte, and neutrophil adhesion to endothelial cells by human milk oligosaccharides. Thromb. Haemost. 2004;92:1402–1410. doi: 10.1160/TH04-01-0055. - DOI - PubMed
    1. Oliveros E., Vazquez E., Barranco A., Ramirez M., Gruart A., Delgado-Garcia J.M., Buck R., Rueda R., Martin M.J. Sialic acid and sialylated oligosaccharide supplementation during lactation improves learning and memory in rats. Nutrients. 2018;10:1519 doi: 10.3390/nu10101519. - DOI - PMC - PubMed
    1. Ten Bruggencate S.J., Bovee-Oudenhoven I.M., Feitsma A.L., van Hoffen E., Schoterman M.H. Functional role and mechanisms of sialyllactose and other sialylated milk oligosaccharides. Nutr. Rev. 2014;72:377–389. doi: 10.1111/nure.12106. - DOI - PubMed
    1. Burns A.J., Rowland I.R. Anti-carcinogenicity of probiotics and prebiotics. Curr. Issues Intest. Microbiol. 2000;1:13–24. - PubMed
Feedback