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Antimicrobial peptide LL-37 promotes the proliferation and invasion of skin squamous cell carcinoma by upregulating DNA-binding protein A

View Article: PubMed Central - PubMed

ABSTRACT

The antimicrobial peptide LL-37 not only contributes to the host defence against microbial invasion but also regulates immune activity, angiogenesis and cell proliferation. Studies have shown that LL-37 participates in the development of a variety of tumours, such as lung cancer, ovarian cancer, breast cancer and melanoma. However, the role of LL-37 in the development of skin squamous cell carcinoma (SCC) is not clear. The present study used immunohistochemistry to confirm that the expression of human DNA-binding protein A (dbpA) was increased in SCC tissues. After stimulating SCC A341 cells, LL-37 was shown promote the proliferation, migration and invasion of these malignant cells. LL-37 also promoted the upregulation of dbpA mRNA and protein expression. In addition, after using small interfering RNA to silence the normal dbpA expression in these malignant cells, the proliferation and invasion of the tumor cells were significantly reduced. When the NF-κB inhibitor PDTC was used to inhibit the process of LL-37-stimulated cells, it was found that the original upregulated expression of dbpA was downregulated. Overall, the present demonstrated that by upregulating the expression of dbpA, LL-37 can promote the proliferation and invasion of tumour cells, and that this process depends on the NF-κB signalling pathway.

No MeSH data available.


(A and B) LL-37 promotes the upregulation of dbpA protein in A431 cells. Time effect: A431 cells were stimulated with 0.5 µg/ml LL-37 for the specified durations. Dose effect: A431 cells were stimulated with the specified doses of LL-37 for 48 h. DbpA protein levels were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. (C) LL-37 promotes the upregulation of dbpA protein in A431 cells. The A431 cells were stimulated with the specified dose of LL-37 for 48 h, and dbpA protein expression levels were determined by immunofluorescence. The figures show dbpA protein fluorescence intensity after stimulation by different concentrations of LL-37. Magnification, ×400. (D) The NF-κB signalling pathway is involved in the upregulation of dbpA stimulated by LL-37 in A431 cells. The A431 cells were pretreated for 30 min with MAPK kinase-extracellular signal-regulated kinase inhibitor (PD98059; 10 µM), MAPK inhibitors (SB203580, 10 µM) or NF-κB inhibitor (PDTC; 1 µM), followed by treatment with 0.5 µg/ml LL-37 for 48 h. The protein levels of dbpA were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. *P<0.05 vs. control. MAPK, mitogen-activated protein kinase kinase; dbpA, DNA-binding protein A; NF-κB, nuclear factor-κB.
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f4-ol-0-0-4865: (A and B) LL-37 promotes the upregulation of dbpA protein in A431 cells. Time effect: A431 cells were stimulated with 0.5 µg/ml LL-37 for the specified durations. Dose effect: A431 cells were stimulated with the specified doses of LL-37 for 48 h. DbpA protein levels were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. (C) LL-37 promotes the upregulation of dbpA protein in A431 cells. The A431 cells were stimulated with the specified dose of LL-37 for 48 h, and dbpA protein expression levels were determined by immunofluorescence. The figures show dbpA protein fluorescence intensity after stimulation by different concentrations of LL-37. Magnification, ×400. (D) The NF-κB signalling pathway is involved in the upregulation of dbpA stimulated by LL-37 in A431 cells. The A431 cells were pretreated for 30 min with MAPK kinase-extracellular signal-regulated kinase inhibitor (PD98059; 10 µM), MAPK inhibitors (SB203580, 10 µM) or NF-κB inhibitor (PDTC; 1 µM), followed by treatment with 0.5 µg/ml LL-37 for 48 h. The protein levels of dbpA were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. *P<0.05 vs. control. MAPK, mitogen-activated protein kinase kinase; dbpA, DNA-binding protein A; NF-κB, nuclear factor-κB.

Mentions: Compared with the control group, stimulation of the A431 cells with LL-37 for 36 h increased the mRNA expression of dbpA (P=0.004), with the most significant increase observed for 0.5 µg/ml LL-37 (P=0.003; Fig. 3C). Western blot showed that after stimulating the A431 cells with LL-37 for 72 h, the protein expression of dbpA increased (P=0.041; Fig. 4A) and again, the most significant increase was observed for 0.5 µg/ml LL-37 (P=0.029; Fig. 4B). Moreover, stimulating the A431 cells with various concentrations of LL-37 increased the fluorescence intensity of dbpA immunostaining, and 0.5 µg/ml was the most effective concentration (Fig. 4C). Thus, LL-37 promoted the expression of dbpA in the A431 cells.


Antimicrobial peptide LL-37 promotes the proliferation and invasion of skin squamous cell carcinoma by upregulating DNA-binding protein A
(A and B) LL-37 promotes the upregulation of dbpA protein in A431 cells. Time effect: A431 cells were stimulated with 0.5 µg/ml LL-37 for the specified durations. Dose effect: A431 cells were stimulated with the specified doses of LL-37 for 48 h. DbpA protein levels were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. (C) LL-37 promotes the upregulation of dbpA protein in A431 cells. The A431 cells were stimulated with the specified dose of LL-37 for 48 h, and dbpA protein expression levels were determined by immunofluorescence. The figures show dbpA protein fluorescence intensity after stimulation by different concentrations of LL-37. Magnification, ×400. (D) The NF-κB signalling pathway is involved in the upregulation of dbpA stimulated by LL-37 in A431 cells. The A431 cells were pretreated for 30 min with MAPK kinase-extracellular signal-regulated kinase inhibitor (PD98059; 10 µM), MAPK inhibitors (SB203580, 10 µM) or NF-κB inhibitor (PDTC; 1 µM), followed by treatment with 0.5 µg/ml LL-37 for 48 h. The protein levels of dbpA were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. *P<0.05 vs. control. MAPK, mitogen-activated protein kinase kinase; dbpA, DNA-binding protein A; NF-κB, nuclear factor-κB.
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f4-ol-0-0-4865: (A and B) LL-37 promotes the upregulation of dbpA protein in A431 cells. Time effect: A431 cells were stimulated with 0.5 µg/ml LL-37 for the specified durations. Dose effect: A431 cells were stimulated with the specified doses of LL-37 for 48 h. DbpA protein levels were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. (C) LL-37 promotes the upregulation of dbpA protein in A431 cells. The A431 cells were stimulated with the specified dose of LL-37 for 48 h, and dbpA protein expression levels were determined by immunofluorescence. The figures show dbpA protein fluorescence intensity after stimulation by different concentrations of LL-37. Magnification, ×400. (D) The NF-κB signalling pathway is involved in the upregulation of dbpA stimulated by LL-37 in A431 cells. The A431 cells were pretreated for 30 min with MAPK kinase-extracellular signal-regulated kinase inhibitor (PD98059; 10 µM), MAPK inhibitors (SB203580, 10 µM) or NF-κB inhibitor (PDTC; 1 µM), followed by treatment with 0.5 µg/ml LL-37 for 48 h. The protein levels of dbpA were determined by western blotting. The figure shows the ratio of dbpA protein/β-actin protein. The results from three independent experiments are shown as the mean ± standard deviation. *P<0.05 vs. control. MAPK, mitogen-activated protein kinase kinase; dbpA, DNA-binding protein A; NF-κB, nuclear factor-κB.
Mentions: Compared with the control group, stimulation of the A431 cells with LL-37 for 36 h increased the mRNA expression of dbpA (P=0.004), with the most significant increase observed for 0.5 µg/ml LL-37 (P=0.003; Fig. 3C). Western blot showed that after stimulating the A431 cells with LL-37 for 72 h, the protein expression of dbpA increased (P=0.041; Fig. 4A) and again, the most significant increase was observed for 0.5 µg/ml LL-37 (P=0.029; Fig. 4B). Moreover, stimulating the A431 cells with various concentrations of LL-37 increased the fluorescence intensity of dbpA immunostaining, and 0.5 µg/ml was the most effective concentration (Fig. 4C). Thus, LL-37 promoted the expression of dbpA in the A431 cells.

View Article: PubMed Central - PubMed

ABSTRACT

The antimicrobial peptide LL-37 not only contributes to the host defence against microbial invasion but also regulates immune activity, angiogenesis and cell proliferation. Studies have shown that LL-37 participates in the development of a variety of tumours, such as lung cancer, ovarian cancer, breast cancer and melanoma. However, the role of LL-37 in the development of skin squamous cell carcinoma (SCC) is not clear. The present study used immunohistochemistry to confirm that the expression of human DNA-binding protein A (dbpA) was increased in SCC tissues. After stimulating SCC A341 cells, LL-37 was shown promote the proliferation, migration and invasion of these malignant cells. LL-37 also promoted the upregulation of dbpA mRNA and protein expression. In addition, after using small interfering RNA to silence the normal dbpA expression in these malignant cells, the proliferation and invasion of the tumor cells were significantly reduced. When the NF-&kappa;B inhibitor PDTC was used to inhibit the process of LL-37-stimulated cells, it was found that the original upregulated expression of dbpA was downregulated. Overall, the present demonstrated that by upregulating the expression of dbpA, LL-37 can promote the proliferation and invasion of tumour cells, and that this process depends on the NF-&kappa;B signalling pathway.

No MeSH data available.