Objective:

2

To investigate the molecular mechanisms underlying the effect of baicalin on prostate cancer (PCa) progression both

in vivo

and

in vitro

.

Methods:

2

The

in situ

PCa stem cells (PCSCs)-injected xenograft tumor models were established in BALB/c nude mice. Tumor volume and weight were respectively checked after baicalin (100 mg/kg) treatment. Hematoxylin-eosin (HE) staining was used to observe the growth arrest and cell necrosis. mRNA expression levels of acetaldehyde dehydrogenase 1 (ALDH1)

CD44

CD133 and Notch1 were determined by reverse transcription-polymerase chain reaction. Protein expression levels of ALDH1

CD44

CD133

Notch1

nuclear factor κB (NF-κB) P65 and NF-κB p-P65 were detected by Western blot. Expression and subcellular location of ALDH1

CD44

CD133

Notch1 and NF-κB p65 were detected by immunofluorescence analysis.

In vitro

cell cycle distribution and cell apoptosis of PC3 PCSCs was assessed by flow cytometry after baicalin (125 μmol/L) treatment. The migration and invasion abilities of PCSCs were assessed using Transwell assays. Transmission electron microscopy scanning was utilized to observe the structure and autophagosome formation of baicalin-treated PCSCs. In addition

PCSCs were infected with lentiviruses expressing human Notch1.

Results:

2

Compared with the control group

the tumor volume and weight were notably reduced in mice treated with 100 mg/kg baicalin (

P

<

0.05 or

P

<

0.01). Histopathological analysis showed that baicalin treatment significantly inhibited cell proliferation and promoted cell apoptosis. Furthermore

baicalin treatment reduced mRNA and protein expression levels of CD44

CD133

ALDH1

and Notch1 as well as the protein expression of NF-κB p-P65 in the xenograft tumor (

P

<

0.01).

In vitro

the cell proliferation of PCSCs was significantly attenuated after treatment with 125 μmol/L baicalin for 72 h (

P

<

0.01). The cell migration and invasion rates were decreased following treatment with baicalin for 48 and 72 h (

P

<

0.01). Baicalin notably induced cell apoptosis and seriously damaged the structure of PCSCs. The mRNA and protein expressions of CD133

CD44

ALDH1 and Notch1 in PCSCs were significantly downregulated following baicalin treatment (

P

<

0.01). Importantly

the inhibitory effects of baicalin on PCa progression and stemness were reversed by Notch1 overexpression (

P

<

0.05 or

P

<

0.01).

Conclusion:

2

Mechanistically

baicalin exhibited a potential therapeutic effect on PCa via inhibiting the Notch1/NF-κB signaling pathway and its mediated cancer stemness.