Involvement of human beta-defensin-2 in regulation of malignant potential of cultured human melanoma cells

BACKGROUND AND AIM

Human beta-defensin-2 (hBD-2) is an antimicrobial cationic peptide capable to control human carcinoma cell growth via cell cycle regulation. The present study was aimed on determination of hBD-2 influence on the growth patterns and malignant potential of cultured human melanoma cells.

METHODS

The study was performed on cultured human melanoma cells of mel Z and mel Is lines treated with recombinant hBD-2 (rec-hBD-2); cell viability, proliferation, cell cycle distribution, and anchorage-independent growth were analyzed using MTT test, direct cell counting, flow cytometry, and colony forming assay respectively. Expression and/or phosphorylation levels of proteins involved in cell cycle control were evaluated by Western blotting.

RESULTS

The treatment of mel Z and mel Is cells with rec-hBD-2 in a concentration range of 100-1000 nM resulted in a concentration-dependent suppression of cell proliferation, viability, and colony forming activity. It has been shown that rec-hBD-2 exerts its growth suppression effects via significant downregulation of B-Raf expression, activation of pRB and upregulation of p21(WAF1) expression, downregulation of cyclin D1 and cyclin E resulting in cell cycle arrest at G1/S checkpoint.

CONCLUSION

According to obtained results, hBD-2 exerts its growth suppression effect toward human melanoma cells via downregulation of B-Raf, cyclin D1 and cyclin E expression, upregulation of p21(WAF1) expression and activation of pRB.

Human beta-defensin-2 controls cell cycle in malignant epithelial cells: in vitro study

AIM

In the present research we analyze the mechanism of human beta-defensin-2 (hBD-2) influence on cultured malignant epithelial cell growth.

MATERIALS AND METHODS

The analysis of a concentration-dependent effect of recombinant hBD-2 (rec-hBD-2) on cell growth patterns and cell cycle distribution has been performed in vitro with 2 cell lines (human lung adenocarcinoma A549 cells and human epidermoid carcinoma A431 cells) using MTT test, flow cytometry and direct cell counting. To study intracellular localization of hBD-2 immunocytofluorescent and immunocytochemical analyses were applied, and effect of hBD-2 on signal cascades involved in cell cycle regulation has been studied by Western blotting.

RESULTS

According to our data, rec-hBD-2 exerts a concentration-dependent effect on the viability of cultured A549 and A431 cells. It causes proproliferative effect at concentrations below 1 nM, significant suppression of cell proliferation at concentration range from 10 nM to 1 μM (p<0.05), and cell death at higher concentrations. Using flow cytometry we have demonstrated that hBD-2 dependent growth suppression is realized via cell cycle arrest at G1/S phase (p<0.05). Also, we have registered significant activation of pRB and decreased expression of Cyclin D1 in cells treated with the defensin compared to untreated control cells, while the expression of p53 remains unaffected. The study of intracellular localization of hBD-2 in these cells has revealed that exogeneously added defensin molecules enter the cells, are distributed throughout the cytoplasm and could be detected in cell nuclei. The model study using A549 cells treated with 1,25-(OH)(2)D(3) has shown similar cell growth suppression effect of native endogenously produced hBD-2.

CONCLUSION

The results of our study suggest that in malignant epithelial cells hBD-2 may control cell growth via arrest of G1/S transition and activation of pRB.

Immunohistochemical analysis of beta-defensin-2 expression in human lung tumors

AIM

The present research was directed on analysis of the expression patterns of human beta-defensin-2 (hBD-2) in human lung tumors.

MATERIALS AND METHODS

Specimens of surgically resected human lung tumors (n = 31) of different histological type (1 case of small cell lung cancer, and 30 cases of non-small cell lung cancer (1 case of clear cell carcinoma, 9 cases of squamous cell carcinoma (SCC), and 20 cases of adenocarcinoma (AC)) were analyzed for expression of hBD-2 with the use of immunohistochemical analysis.

RESULTS

Immunohistochemical analysis has revealed that all lung tumor samples independently on their histological type express hBD-2 peptide, however at different levels (from < 5% to 100% cells). According to our observations, low-differentiated AC differs from moderately differentiated AC by significantly lower hBD-2 expression levels (p < 0.05). No correlation between hBD-2 expression patterns and PCNA or Bcl-2 expression has been found.

CONCLUSION

Human beta-defensin-2 expression levels may depend on differentiation grade of lung adenocarcinoma.

Administration of vitamin D3 improves antimetastatic efficacy of cancer vaccine therapy of Lewis lung carcinoma

AIM

To analyze antitumor efficacy of experimental cancer vaccine therapy combined with introduction of vitamin D3 (VD3) for treatment of Lewis lung carcinoma (3LL).

MATERIALS AND METHODS

Cancer vaccines composed from recombinant murine beta-defensin-2 (mBD-2) and 3LL cell lysate, or DNA, coding for mBD-2-Muc1 fusion construct cloned in pcDNA3+ vector, were prepared and used for intradermal vaccination. Experimental cancer vaccines introduced i. d. at therapeutic and prophylactic regimens to 3LL-bearing C57Bl mice, were applied alone or in combination with VD3 (administered per os) and/or low-dose cyclophosphamide (CP, administered intraperitoneal). Efficacy of treatments was analyzed by primary tumor growth dynamics indexes and by metastasis rate in vaccinated animals.

RESULTS

As it has been shown, administration of the protein-based vaccine composed from mBD-2 and 3LL cell lysate in combination with VD3 and CP, but not in VD3 free setting, led to significant suppression of primary tumor growth (p < 0.005) and had significant antimetastatic effect. Introduction of VD3 with or without CP in the scheme of treatment with mBD- 2-Muc1-DNA vaccine at therapeutic regimen has led to significant suppression of primary tumor (p < 0.05) and metastasis volumes (p < 0.005), while in the groups of animals treated with DNA-vaccine + VD3 with or without CP at prophylactic regimen, significant antimetastatic effect (p < 0.05) and elevation of average life-span (p < 0.05) have been registered.

CONCLUSION

The results of this pilot study have shown promising clinical effects of VD3 administration in combination with cancer vaccinotherapy in vivo.

Expression patterns of murine beta-defensin-2 mRNA in Lewis lung carcinoma cells in vitro and in vivo

AIM

To evaluate the anti-tumor activity of murine beta-defensin-2 (mBD-2) expression in vitro and in vivo.

MATERIALS AND METHODS

Based on pcDNA3 vector, constructs containing mBD-2 cDNA coding mature defensin molecule (pcDNA3-mBD2), and Igk-mBD-2 insertion, coding secretory sequence plus mature defensin molecule (pcDNA3-Igk-mBD-2) were generated. Lewis lung carcinoma (3LL) cells were transfected in vitro with these plasmids and with blank pcDNA3 vector, and the proliferative rate and clonogenic ability of obtained cell lines cultivated in vitro were analyzed using (3)H-incorporation technique and colony formation in semi-soft medium, respectively. Expression of mBD-2 mRNA was studied by semiquantative RT-PCR analysis. Also, transfected cells were transplanted to C57B mice, and the patterns of tumor growth in vivo were analyzed by routine techniques.

RESULTS

We have found out that in the 3LL cells transfected with pcDNA3-mBD-2 and pcDNA3-Igk-mBD-2, the expression of mBD-2 mRNA is significantly down regulated compared to wild-type cells and 3LL cells transfected with blank vector. The cells with suppressed mBD-2 expression differed from parental cells and cells transfected with blank vector by higher proliferation rate (p < 0.001) and higher clonogenic ability. The 3LL-mBD-2 and 3LL-Igk-mBD-2 cells that are transplanted to C57B mice gave rise to more aggressive tumors that possessed significantly higher growth rate (p < 0.01) than those that arise from wild-type 3LL cells.

CONCLUSION

The obtained results indicate the relation between mBD-2 expession in 3LL cells and their proliferation rate and malignant phenotype, and also allow to hypothesize the possibility of regulation of mBD-2 mRNA expression in these cells by a feedback mechanism.

Expression of human beta-defensins-1, 2 and 4 mRNA in human lung tumor tissue: a pilot study

AIM

To analyze the patterns of human beta-defensin-1, 2, 4 (hBDs) expression in human lung tumors.

MATERIALS AND METHODS

Tissue samples of surgically resected human lung tumors (squamous cell carcinoma (SCC), n=10; adenocarcinoma (AC), n=10) paired with conditionally normal tissue samples were analyzed for expression of hBD-1, 2, 4 mRNA by semiquantitative RT-PCR.

RESULTS

In a number of studied lung cancer tissue samples, overexpression of defensin mRNA was registered: hBD-1 mRNA (50% of SCC and 60% AC), hBD-2 mRNA (60% of SCC and 50% of AC) or hBD-4 (40% of SCC and 20% AC). No correlation was detected between the levels of hBD-1, hBD-2 and hBD-4 mRNA and histological type, differentiation grade of the tumor, and the stage of the disease, as well as the content of hBD-2 peptide in blood serum of lung cancer patients.

CONCLUSION

Human beta-defensins-1 and -2 are often up-regulated in human lung tumors.

Regulated expression of human beta-defensin-2 leads to altered phenotype and growth patterns of cultured human embryonal kidney cells

AIM

To create cell line with regulated expression of human beta-defensin-2 (hBD-2) and evaluate the influence of expressed peptide on its phenotypic and growth patterns.

MATERIALS AND METHODS

Using cloning techniques, on the base of human embryonic kidney cells of HEK293T line, stable T-rex HEK-hBD2-m cell subline expressing mature biologically active hBD-2 molecule upon the presence of tetracycline in culture medium was generated. The morphological patterns, growth characteristics and colony forming activity of these cells were studied using routine techniques.

RESULTS

T-rex HEK-HBD2-m cell subline was shown to express both mRNA and hBD-2m protein upon the presence of 1 mug/ml tetracycline in culture medium as it was demonstrated by RT-PCR and immunocytochemical approach. Upon prolonged expression of hBD-2, the cells acquired special features: they lost ability to grow in monolayer in vitro and to form colonies in soft agar, characteristic to parental HEK293T cells, but possess higher growth rate and longer survival in FBS-free medium than wild type cells.

CONCLUSION

Expression of hBD-2 in T-rex HEK-HBD2-m cell subline results in specific biological consequences that favor cell survival.

Involvement of human beta-defensin-2 in intracellular signaling: in vitro study

AIM

To analyze involvement of human beta-defensin-2 (hBD-2) in intracellular signaling in vitro.

MATERIALS AND METHODS

A431cells were cultured in the presence of 1 microg/ml of recombinant hBD-2 and/or 10 ng/ml EGF. For evaluation of expression of mRNAs for p70S6 kinase, isoforms alpha and beta, RT-PCR analysis was applied. Expression and activity of p70S6K, phosphorylation of PDK1, ERK, JNK, p38 kinases and EGF receptor (EGFR) was evaluated using Western blot analysis.

RESULTS

30 min incubation of A431 cells with 1 mug/ml of hBD-2 didn't influence autophosphorylation level of EGFR, but resulted in activation of p70S6K, 12 h treatment - in prominently increased level of mRNA for alpha and beta-isoforms of p70S6 kinase, whilst 24 h treatment - in elevation of p70S6K synthesis on protein level. Up-stream kinase phosphorylating p70S6K, PDK1, is also phosporylated upon influence of exogenous hBD-2 in vitro.

CONCLUSION

Our data point on the involvement of PDK1-p70S6K pathway in mediation of action of hBD-2 in A431 cells.

Involvement of human beta-defensin-2 in proliferation of transformed cells of human cervix

AIM

To evaluate the influence of human beta-defensin-2 (hBD-2) on viability and proliferation of cultured human epithelial cells and the patterns of hBD-2 expression in normal tissues and early-stage human cervical neoplasia in the relation to proliferative state of these cells.

MATERIALS AND METHODS

The influence of recombinant hBD-2 on viability and proliferation of cultured cells of A431 and M-HeLa lines in vitro was performed by MTT-test, 3H-thymidine incorporation and cell counting techniques. Immunohistochemical analysis of expression of hBD-2 and PCNA in tissue samples (10 normal cases (control), 30 carcinomas of the cervix uteri: 15 - squamous cell carcinoma in situ (Stage 0), and 15 squamous cell carcinoma (Stage Ia)) was performed with the use of anti-hBD-2 and anti-PCNA-mAbs, respectively.

RESULTS

We have revealed that hBD-2 significantly stimulated proliferation of A431 and M-HeLa cells in a concentration-dependent manner in the range of 0.1-2 microg/ml, whilst at higher concentrations (> 3-5 microg/ml) it negatively influenced cell viability. The results of immunohistochemical study have shown that malignant transformation of human cervical epithelium is accompanied by the increase of expression of hBD-2 and PCNA. However, the correlative analysis of the expression of the mentioned markers has revealed no relation between them.

CONCLUSION

The effect of hBD-2 on viability and proliferation of cultured epithelial cells possesses a concentration-dependent character. Expression of hBD-2 is increased in early-stage cervical carcinoma.