Pattern of expression of beta-defensins in oral squamous cell carcinoma

Human β-defensins and their synthetic analogs: Natural defenders and prospective new drugs of oral health

As a family of cationic host defense peptides, human β-defensins (HBDs) are ubiquitous in the oral cavity and are mainly synthesized primarily by epithelial cells, serving as the primary barrier and aiming to prevent microbial invasion, inflammation, and disease while maintaining physiological homeostasis. In recent decades, there has been great interest in their biological functions, structure-activity relationships, mechanisms of action, and therapeutic potential in oral diseases. Meanwhile, researchers are dedicated to improving the properties of HBDs for clinical application. In this review, we first describe the classification, structural characteristics, functions, and mechanisms of HBDs. Next, we cover the role of HBDs and their synthetic analogs in oral diseases, including dental caries and pulp infections, periodontitis, peri-implantitis, fungal/viral infections and oral mucosal diseases, and oral squamous cell carcinoma. Finally, we discuss the limitations and challenges of clinical translation of HBDs and their synthetic analogs, including, but not limited to, stability, bioavailability, antimicrobial activity, resistance, and toxicity. Above all, this review summarizes the biological functions, mechanisms of action, and therapeutic potential of both natural HBDs and their synthetic analogs in oral diseases, as well as the challenges associated with clinical translation, thus providing substantial insights into the laboratory development and clinical application of HBDs in oral diseases.

Human β-Defensins in Diagnosis of Head and Neck Cancers

Head and neck cancers are malignant growths with high death rates, which makes the early diagnosis of the affected patients of utmost importance. Over 90% of oral cavity cancers come from squamous cells, and the tongue, oral cavity, and salivary glands are the most common locations for oral squamous cell carcinoma lesions. Human β-defensins (hBDs), which are mainly produced by epithelial cells, are cationic peptides with a wide antimicrobial spectrum. In addition to their role in antimicrobial defense, these peptides also take part in the regulation of the immune response. Recent studies produced evidence that these small antimicrobial peptides are related to the gene and protein expression profiles of tumors. While the suppression of hBDs is a common finding in head and neck cancer studies, opposite findings were also presented. In the present narrative review, the aim will be to discuss the changes in the hBD expression profile during the onset and progression of head and neck cancers. The final aim will be to discuss the use of hBDs as diagnostic markers of head and neck cancers.

Defensin alpha 6 (DEFA6) is a prognostic marker in colorectal cancer

Defensin alpha 6 (DEFA6) is a member of the alpha defensin family of microbicidal and cytotoxic peptides that defend against bacteria and viruses. Here, we provide a novel function of DEFA6 in tumorigenesis of colorectal cancer (CRC) in vitro and in vivo. Specifically, DEFA6 is highly expressed in both CRC cancer cell lines as well as patient-derived samples at the level of RNA and protein. By shRNA-mediated loss of function of DEFA6, we found that proliferation, migration, invasion, colony forming ability of CRC cell lines were impaired in the absence of DEFA6 in vitro. Furthermore, DEFA6-deficient cancer cells exhibited significantly reduced growth rates compared to control cells in vivo. More importantly, by analyzing 352 patient-derived samples, we revealed that DEFA6 is associated with overall survival rate of CRC patients and thus an independent prognostic marker for CRC. These results suggest that DEFA6 plays an essential oncogenic role in CRC and serves a good therapeutic target for the disease.

Human Beta Defensins and Cancer: Contradictions and Common Ground

Human beta-defensins (hBDs, −1, 2, 3) are a family of epithelial cell derived antimicrobial peptides (AMPs) that protect mucosal membranes from microbial challenges. In addition to their antimicrobial activities, they possess other functions; e.g., cell activation, proliferation, regulation of cytokine/chemokine production, migration, differentiation, angiogenesis, and wound healing processes. It has also become apparent that defensin levels change with the development of neoplasia. However, inconsistent observations published by various laboratories make it difficult to reach a consensus as to the direction of the dysregulation and role the hBDs may play in various cancers. This is particularly evident in studies focusing on oral squamous cell carcinoma (OSCC). By segregating each hBD by cancer type, interrogating methodologies, and scrutinizing the subject cohorts used in the studies, we have endeavored to identify the “take home message” for each one of the three hBDs. We discovered that (1) consensus-driven findings indicate that hBD-1 and−2 are down- while hBD-3 is up-regulated in OSCC; (2) hBD dysregulation is cancer-type specific; (3) the inhibition/activation effect an hBD has on cancer cell lines is related to the direction of the hBD dysregulation (up or down) in the cancer from which the cell lines derive. Therefore, studies addressing hBD dysregulation in various cancers are not generalizable and comparisons should be avoided. Systematic delineation of the fate and role of the hBDs in a specific cancer type may lead to innovative ways to use defensins as prospective biomarkers for diagnostic/prognostic purposes and/or in novel therapeutic modalities.

Human β-Defensin 2 Expression in Oral Epithelium: Potential Therapeutic Targets in Oral Lichen Planus

Human β-defensin 2 (hBD-2) is a potent antimicrobial peptide that participates in defense against invading bacteria. We recently showed that bacterial components and histamine, through histamine H4 receptor (H4R), are involved in the pathogenesis of the potentially malignant lesion, oral lichen planus (OLP). However, the underlying mechanisms remain unknown. We, therefore, investigated the role of hBD2–histamine crosstalk signaling in promoting OLP pathology. Biopsies from OLP and oral tongue squamous cell carcinoma (OTSCC) patients, and healthy controls were used. Two OTSCC cell lines and normal human oral keratinocytes (HOKs) were used. HBD-2 and other targets were mapped by immunostaining and analyzed by ImageJ2 software. The highly sensitive droplet-digital PCR technology and qRT-PCR were utilized to study the clinically derived and in vitro samples, respectively. H4R was challenged with the specific agonist HST-10 and inverse agonist ST-1007. HBD-2 was highly induced in OLP lesions. In contrast, hBD2 expression was attenuated in OTSCC tissues, while very low levels of hBD-2 messenger RNA (mRNA) were observed in OTSCC cells. Together with tumor necrosis factor-α (TNF-α), histamine upregulated hBD-2 mRNA expression in HOKs. Activation of H4R seems to modulate the expression of epithelial hBD-2. These findings suggest the involvement of hBD-2 in the pathogenesis of OLP and may, thus, be harnessed for therapeutic interventions in OLP.

Human antimicrobial peptides and cancer

Antimicrobial peptides (AMPs) have long been a topic of interest for entomologists, biologists, immunologists and clinicians because of these agents' intriguing origins in insects, their ubiquitous expression in many life forms, their capacity to kill a wide range of bacteria, fungi and viruses, their role in innate immunity as microbicidal and immunoregulatory agents that orchestrate cross-talk with the adaptive immune system, and, most recently, their association with cancer. We and others have theorized that surveillance through epithelial cell-derived AMPs functions to keep the natural flora of microorganisms in a steady state in different niches such as the skin, the intestines, and the mouth. More recently, findings related to specific activation pathways of some of these AMPs have led investigators to associate them with pro-tumoral activity; i.e., contributing to a tumorigenic microenvironment. This area is still in its infancy as there are intriguing yet contradictory findings demonstrating that while some AMPs have anti-tumoral activity and are under-expressed in solid tumors, others are overexpressed and pro-tumorigenic. This review will introduce a new paradigm in cancer biology as it relates to AMP activity in neoplasia to address the following questions: Is there evidence that AMPs contribute to tumor promoting microenvironments? Can an anti-AMP strategy be of use in cancer therapy? Do AMPs, expressed in and released from tumors, contribute to compositional shifting of bacteria in cancerous lesions? Can specific AMP expression characteristics be used one day as early warning signs for solid tumors?

Clinical chorioamnionitis at term II: the intra-amniotic inflammatory response

OBJECTIVE

Recent studies indicate that clinical chorioamnionitis is a heterogeneous condition and only approximately one-half of the patients have bacteria in the amniotic cavity, which is often associated with intra-amniotic inflammation. The objective of this study is to characterize the nature of the inflammatory response within the amniotic cavity in patients with clinical chorioamnionitis at term according to the presence or absence of 1) bacteria in the amniotic cavity and 2) intra-amniotic inflammation.

MATERIALS AND METHODS

A retrospective cross-sectional case-control study was conducted to examine cytokine and chemokine concentrations in the amniotic fluid (AF). Cases consisted of women with clinical chorioamnionitis at term (n=45). Controls were women with uncomplicated pregnancies at term who did not have intra-amniotic inflammation and were in labor (n=24). Women with clinical chorioamnionitis were classified according to the results of AF cultures, broad-range polymerase chain reaction coupled with electrospray ionization mass spectrometry, and AF concentration of interleukin-6 (IL-6) into those: 1) without intra-amniotic inflammation, 2) with microbial-associated intra-amniotic inflammation, and 3) with intra-amniotic inflammation without detectable bacteria. The AF concentrations of 29 cytokines/chemokines were determined using sensitive and specific V-PLEX immunoassays.

RESULTS

1) The AF concentrations of pro- and anti-inflammatory cytokines/chemokines such as interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-4 (IL-4), macrophage inflammatory protein-1 beta (MIP-1β), and interleukin-8 (IL-8) (except Eotaxin-3) were significantly higher in women with clinical chorioamnionitis at term than in controls (term labor without intra-amniotic inflammation); 2) patients with microbial-associated intra-amniotic inflammation, and those with intra-amniotic inflammation without detectable bacteria, had a dramatic differential expression of cytokines and chemokines in AF compared to patients with spontaneous labor without intra-amniotic inflammation. However, no difference could be detected in the pattern of the intra-amniotic inflammatory response between patients with intra-amniotic inflammation with and without detectable bacteria; and 3) in patients with clinical chorioamnionitis at term but without intra-amniotic inflammation, the behavior of cytokines and chemokines in the AF was similar to those in spontaneous labor at term.

CONCLUSIONS

Patients with clinical chorioamnionitis who had microbial-associated intra-amniotic inflammation or intra-amniotic inflammation without detectable bacteria had a dramatic upregulation of the intra-amniotic inflammatory response assessed by amniotic fluid concentrations of cytokines. A subset of patients with term clinical chorioamnionitis does not have intra-amniotic infection/inflammation, as demonstrated by elevated AF concentrations of inflammation-related proteins, when compared to women in term labor with uncomplicated pregnancies, suggesting over-diagnosis. These observations constitute the first characterization of the cytokine/chemokine network in the amniotic cavity of patients with clinical chorioamnionitis at term.

Oncogenic relevant defensins: expression pattern and proliferation characteristics of human tumor cell lines

The objective of this study was to investigate gene expression levels of oncogenic relevant human defensins and their impact on proliferation rates of 29 cell lines derived from main types of different tumor origins. Differential gene expression analysis of human defensins was performed by real-time PCR experiments. The proliferation rate of tumor cells that had been cultivated in the absence or presence of biologically active peptides was analyzed with a lactate dehydrogenase assay kit. At least one member of the defensin family was expressed in each tumor cell line, whereby α-defensin (DEFA1), DEFA2, or DEFA3 transcripts could be ubiquitously detected. Cell lines of neural origin (glioma, neuroblastoma, and small-cell lung carcinoma) expressed far less human β-defensins (hBDs) in comparison to other tumor types. The expression level of a specific defensin in various cell lines could vary by more than five orders of magnitude. Compensatory mechanisms on the expression levels of the different defensins could not be strictly observed. Only in 3 out of 29 tumor cell lines the proliferation rate was affected after defensin stimulation. The variable appearance of defensins, as well as the cell line-restricted functional activity, argues for the integration of defensins in complex cellular and molecular networks that tolerate rather flexible expression patterns.

Overexpression of human β-defensin 2 promotes growth and invasion during esophageal carcinogenesis

Human β-defensin 2 (HBD-2) is an antimicrobial peptide produced by mucosal surfaces in response to microbial exposure or inflammatory cytokines. Although HBD-2 is expressed in the esophagus in response to stress and infectious agents, little is known regarding its expression and functional role in esophageal carcinogenesis. In the current investigation, normal esophagus and N-nitrosomethylbenzylamine (NMBA)-induced precancerous and papillomatous lesions of the rat esophagus were characterized for HBD-2 encoding gene Defb4 and protein. HBD-2 was found to be overexpressed in esophagi of rats treated with NMBA compared to animals in control group. Results of Real-time PCR, Western blot and immunohistochemistry demonstrated a positive correlation between the overexpression of HBD-2 and the progression of rat squamous cell carcinogenesis (SCC) in the esophagus. We also observed that HBD-2 is overexpressed in tumor tissues removed from patients with esophageal SCC. Moreover, Defb4 silencing in vitro suppresses the tumor cell proliferation, mobility and invasion in esophageal SCC cell line KYSE-150. The results from this study provide experimental evidence that HBD-2 may play an oncogenic role in the initiation and progression of esophageal SCC and thus serves as a target for chemopreventive and therapeutic interventions.

HBD-2 is downregulated in oral carcinoma cells by DNA hypermethylation, and increased expression of hBD-2 by DNA demethylation and gene transfection inhibits cell proliferation and invasion

Human β-defensin-2 (hBD-2) is a type of epithelial antimicrobial peptide. The expression level of hBD-2 mRNA is lower in oral carcinoma cells (OCCs) than in healthy oral epithelium. Yet, it is still unknown how hBD-2 expression is downregulated in OCCs. The present study investigated DNA hypermethylation of hBD-2 in OCCs and the effect of the demethylation and increased expression of hBD-2 on cell proliferation and invasion. Six different types of oral carcinoma cell lines (OSC-19, BSC-OF, SAS, HSC-2, HSC-4 and HSY) and normal oral keratinocytes (NOKs) were used. The expression levels of hBD-2 in all OCCs were significantly lower than that in the NOKs. Treatment with DNA methyltransferase inhibitor, 5-aza-dC, at the concentration of 50 µM significantly induced upregulation of expression of hBD-2 in the OCCs. Using methylation-specific PCR, DNA hypermethylation was observed in all OCCs. These results suggest that DNA hypermethylation is, at least in part, involved in the decreased expression of hBD-2 in OCCs. We examined the effect of 5-aza-dC on the cell proliferation and invasive ability of OCCs. The cell invasion assays showed that the number of OCCs treated with 5-aza-dC on the filters was significantly lower than that of the controls. We examined whether increased expression of hBD-2 generated by gene transfection inhibited the proliferation and invasion of SAS cells. The number of SAS cells exhibiting increased expression of hBD-2 on the filters in the invasion assay were significantly lower on day 7 when compared with the control. hBD-2 may function as a tumor suppressor. Increased expression of hBD-2 induced by demethylation or increased expression generated by gene transfection may be useful therapeutic methods for oral carcinoma.

Human beta-defensin-1 suppresses tumor migration and invasion and is an independent predictor for survival of oral squamous cell carcinoma patients

Background

Human beta-defensin-1 (hBD-1) has recently been considered as a candidate tumor suppressor in renal and prostate cancer. The aim of this study was to investigate the role of hBD-1 in the progression of oral squamous cell carcinoma (OSCC) and its potential as diagnostic/prognostic biomarker and therapeutic target for OSCC.

Methods

HBD-1 expression in tissues at different stages of oral carcinogenesis, as well as OSCC cell lines was examined. HBD-1 was overexpressed in HSC-3, UM1, SCC-9 and SCC-25 cells and subjected to cell growth, apoptosis, migration and invasion assays. Tissue microarray constructed with tissues from 175 patients was used to examine clinicopathological significance of hBD-1 expression in OSCC.

Results

HBD-1 expression decreased from oral precancerous lesions to OSCC and was lower in OSCC with lymph node metastasis than those without metastasis. In vitro, the expression of hBD-1 was related to the invasive potential of OSCC cell lines. Induction of exogenous expression of hBD-1 inhibited migration and invasion of OSCC cells, probably by regulation of RhoA, RhoC and MMP-2; but had no significant effect on proliferation or apoptosis. In a cohort of patients with primary OSCC, cases with no expression of hBD-1 had more chance to be involved in lymph node metastasis. Eventually, the positive expression of hBD-1 was associated with longer survival of patients with OSCC, and multivariate analysis and ROC curve analysis confirmed hBD-1 positivity to be an independent prognostic factor of OSCC, especially OSCC at early stage.

Conclusions

Overall, these data indicated that hBD-1 suppressed tumor migration and invasion of OSCC and was likely to be a prognostic biomarker and a potential target for treatment of OSCC.

Expression profile of drosomycin-like defensin in oral epithelium and oral carcinoma cell lines

OBJECTIVE

Drosomycin-like defensin (DLD) is a recently discovered antimicrobial peptide mainly active against filamentous fungi. The present study investigated the expression profile of DLD in oral epithelium and oral squamous cell carcinoma (SCC) cell lines.

METHODS

Tissue sections of human oral mucosa, keratinocytes derived from oral mucosa (NOK) and eight kinds of SCC cell lines were used. In situ hybridization was performed on tissue sections of oral mucosa. Expression levels of DLD in the cells were observed by reverse transcription polymerase chain reaction (RT-PCR) and real-time RT-PCR assays. The cells were treated with IL-1β, IL-8 and TNF-α, and agonists for TLR2, TLR4 and β-glucan. DLD expression in cells was increased and decreased by the DLD gene and its siRNA transfection, respectively. The proliferation rates were assessed by cell counting.

RESULTS

By means of in situ hybridization, DLD mRNA positive staining was detected in the epithelial layer of the oral mucosa. An RT-PCR assay confirmed the expression of DLD mRNA in keratinocytes derived from oral epithelium. Expression of DLD in two out of eight cell lines was significantly lower than in NOK cells. The expression levels of DLD mRNA were not significantly changed in the cells stimulated with any cytokines or agonists. The cell proliferation rate where there was decreased expression of DLD was significantly lower than in the control.

CONCLUSION

DLD may be partially involved in the defence against filamentous fungal infection in the oral mucosa, and may also serve other functions, such as contribution to cell growth.

The yin and yang of human Beta-defensins in health and disease

Rapidly evolving research examining the extended role of human beta-defensins (hBDs) in chemoattraction, innate immune-mediated response, and promotion of angiogenesis suggest that the collective effects of hBDs extend well beyond their antimicrobial mechanism(s). Indeed, the numerous basic cellular functions associated with hBDs demonstrate that these peptides have dual impact on health, as they may be advantageous under certain conditions, but potentially detrimental in others. The consequences of these functions are reflected in the overexpression of hBDs in diseases, such as psoriasis, and recently the association of hBDs with pro-tumoral signaling. The mechanisms regulating hBD response in health and disease are still being elucidated. Clearly the spectrum of function now attributed to hBD regulation identifies these molecules as important cellular regulators, whose appropriate expression is critical for proper immune surveillance; i.e., expression of hBDs in proximity to areas of cellular dysregulation may inadvertently exacerbate disease progression. Understanding the mechanism(s) that regulate contextual signaling of hBDs is an important area of concentration in our laboratories. Using a combination of immunologic, biochemical, and molecular biologic approaches, we have identified signaling pathways associated with hBD promotion of immune homeostasis and have begun to dissect the inappropriate role that beta-defensins may assume in disease.

Beta-defensins: what are they really doing in the oral cavity?

Initially identified as broad-spectrum antimicrobial peptides, the members of the β-defensin family have increasingly been observed to exhibit numerous other activities, both in vitro and in vivo, that do not always relate directly to host defense. Much research has been carried out in the oral cavity, where the presence of commensal bacteria further complicates the definition of their role. In addition to direct antimicrobial activity, β-defensins exhibit potent chemotactic activity for a variety of innate immune cells, as well as stimulating other cells to secrete cytokines. They can also inhibit the inflammatory response, however, by the specific binding of microbe-associated molecular patterns. These patterns are also able to induce the expression of β-defensins in gingival epithelial cells, although significant differences are observed between different species of bacteria. Together these results suggest a complex model of a host-defense related function in maintenance of bacterial homeostasis and response to pathogens. This model is complicated, however, by numerous other observations of β-defensin involvement in cell proliferation, wound healing and cancer. Together, the in vitro, in vivo and human studies suggest that these peptides are important in the biology of the oral cavity; exactly how is still subject to speculation.

Human beta-defensin-1, -2, and -3 exhibit opposite effects on oral squamous cell carcinoma cell proliferation

The objective of this study was to investigate the impact of human beta-defensins (hBDs) on oral squamous cell carcinoma (OSCC) proliferation and hBD expression in vitro. BHY-OSCC cell lines were stimulated with hBD-1, -2, and -3. Proliferation of BHY cells was ascertained and hBD-mRNA expression was evaluated by real-time PCR. Proliferation of BHY cells decreased by 25% in response to hBD-1 stimulation but increased after stimulation with hBD-2 and -3. HBD-1 stimulation enhanced hBD-3 expression, whereas HBD-2 stimulation decreased early hBD-3 expression. HBD-3 stimulation enhanced hBD-1 expression. HBDs profoundly impact on OSCC proliferation and hBD expression in vitro. Therefore, hBD-1 might function as a tumor suppressor gene in OSCCs, while hBD-2 and -3 might be protooncogenes.

Expression profile of human beta-defensin 3 in oral squamous cell carcinoma

Although it is known that innate immunity is important for protecting the body against foreign agents such as bacteria, little is known about elements of the innate immune system that have antitumor activity. This prospective study was designed to investigate the function of human beta-defensin 3 (hBD-3), an important component of the innate immune response, in oral squamous cell carcinoma (OSCC). Paired cancerous and noncancerous specimens of 45 patients who underwent surgical treatment for OSCC were examined for hBD-3 expression on protein and mRNA. Clinical and pathological features such as age, gender, tumor and lymph node status, UICC stage, and histological grading were correlated. hBD-3 was significantly overexpressed in tumors in comparison to healthy tissue examined with real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) analysis (p = .004). Immunohistochemical stain for hBD-3 was much more pronounced in tumors than in corresponding healthy mucosa. The results illustrate that hBD-3 is frequently overexpressed in oral squamous cell carcinomas and seems to be related to oncogenesis. Increased expression of hBD-3 in oral squamous cell carcinomas suggests its potential role in the pathogenesis of oral cancer. This might be a starting point for novel pharmacological/molecular treatment modalities.

Significant upregulation of antimicrobial peptides and proteins in lichen sclerosus

BACKGROUND

Lichen sclerosus (LS) is a chronic inflammatory T cell-driven sclerotic skin condition in which skin barrier disruption frequently occurs. Inflamed and injured epithelia are a particularly rich source of antimicrobial peptides and proteins (AMPs).

OBJECTIVES

We aimed to investigate for the first time the expression pattern of AMPs in lesions of LS as compared with healthy skin.

METHODS

Twenty-four women with LS as well as 10 healthy women were included in the study. In order to assess the expression of human beta-defensin (hBD)-1, hBD-2, hBD-3, psoriasin (S100A7), the cathelicidin LL-37 and RNase 7, real-time reverse transcriptase-polymerase chain reaction and immunohistochemistry were performed on skin specimens obtained from lesional and healthy skin of the genital region, respectively.

RESULTS

Median hBD-2 mRNA levels observed in LS were significantly higher than in controls (0.15 vs. 0.008; P = 0.0037). Moreover, psoriasin (98.2 vs. 28.1; P = 0.0052) mRNA expression was significantly higher in LS lesions as compared with controls. Significant differences in mRNA expression of hBD-2 and psoriasin were also confirmed by immunohistochemistry. For hBD-1, hBD-3, LL-37 and RNase 7, levels did not differ significantly or were significant only at the gene level but not protein level.

CONCLUSIONS

We have demonstrated that hBD-2 and psoriasin expression levels in lesional skin of patients with LS are significantly increased when compared with healthy controls. Whether this observation simply reflects an innate defence response caused by an increased risk of local infection, or whether our data indicate a pathogenetic role of AMPs in LS, will be addressed in future studies.

PAX2 oncogene negatively regulates the expression of the host defense peptide human beta defensin-1 in prostate cancer

Human beta defensin-1 (hBD1) is a component of the immune system which links the innate and adaptive immune responses. We have demonstrated that hBD1 induces rapid cytolysis of prostate cancer cells and that it may also possess tumor suppressive abilities. In addition, there is a high frequency of cancer-specific loss of hBD1 expression which further suggests its potential role in tumor progression. However, the factors responsible for the loss of hBD1 expression are not known. PAX2, a transcriptional regulator normally expressed during early development, has been implicated as an oncogene in carcinomas of the kidney, prostate, breast and ovary. It is known that expression of PAX2 in these tumor cells mediates the evasion of cell death through the suppression of cell death pathways involving the p53 tumor suppressor. However, we have demonstrated that knock-down of PAX2 expression results in cell death independent of p53 status, thus suggesting that additional cell death pathways are negatively regulated by PAX2. Here we describe a novel pathway in which PAX2 represses hBD1 expression through binding of the PAX2 homeodomain to the hBD1 promoter. Furthermore, knock-down of PAX2 expression results in the re-expression of hBD1, and subsequently prostate cancer cell death. These findings are the first to demonstrate that the PAX2 oncogene suppresses hBD1 expression in cancer and further implicate PAX2 as a novel therapeutic target for prostate cancer treatment.

TLR signaling by tumor and immune cells: a double-edged sword

The tumor cell signaling pathways that trigger the uncontrolled proliferation, resistance to apoptosis, metastasis and escape from immune surveillance are partially understood. Toll-like receptors (TLRs), which recognize a variety of pathogen-associated molecular patterns, are centrally involved in the initiation of the innate and adaptive immune responses. However, recent evidence shows that functional TLRs are also expressed on a wide variety of tumors suggesting that TLRs may play important roles in tumor biology. Activation of tumor cell TLRs not only promotes tumor cell proliferation and resistance to apoptosis, but also enhances tumor cell invasion and metastasis by regulating metalloproteinases and integrins. Moreover, the activation of TLR signaling in tumor cells induces the synthesis of proinflammatory factors and immunosuppressive molecules, which enhance the resistance of tumor cells to cytotoxic lymphocyte attack and lead to immune evasion. Thus, the neoplastic process may usurp TLR signaling pathways to advance cancer progression, which suggests that targeting tumor TLR signaling pathways may open novel therapeutic avenues.

Role of beta-defensins in oral epithelial health and disease

The oral epithelium functions as a mechanical and protective barrier to resist bacterial infection. beta-Defensins are a group of antimicrobial peptides mainly produced by epithelial cells of many organs including skin, lung, kidney, pancreas, uterus, eye, and nasal and oral mucosa. This review focuses on beta-defensins (BDs) in oral epithelia and discusses their importance in oral epithelial health and disease. BDs exhibit antimicrobial activity against oral microbes including periodontitis-related bacteria, Candida, and papilloma virus. Alterative expression of BDs was observed in oral epithelial diseases, including oral inflammatory lesions with and without microbial infection and oral cancer. BDs may be useful in the treatment of oral infectious diseases, ulcerative lesions, and cancer. BDs play an important role in protection against oral microbes and may be used in clinical applications.

Human ? defensin-1 and -2 expression in the gingiva of patients with specific periodontal diseases

BACKGROUND AND OBJECTIVE

beta defensin antimicrobial peptides are important in epithelial innate immunity, and their differential expression is associated with periodontal diseases. The aims of this study were to determine the mRNA expression of human beta defensin-1 and -2 in the gingival tissue of patients with gingivitis, aggressive periodontitis and chronic periodontitis, and to evaluate the relationship between defensin expression and type and/or severity of periodontal destruction.

MATERIAL AND METHODS

Fifteen patients in each group with gingivitis, aggressive periodontitis and chronic periodontitis, and 10 healthy subjects, were included in the study (n=55). The periodontal status of the subjects was determined by periodontal clinical measurements and radiographical evaluations. Transcriptional levels of human beta defensin-1 and -2 genes in gingival samples were assessed by using the quantitative real-time polymerase chain reaction technique, and the data were evaluated statistically by the relative expression Software Tool 2 for groupwise comparisons.

RESULTS

Expression of the human beta defensin-1 gene was lower in gingivitis and aggressive periodontitis groups, and significantly higher in the chronic periodontitis group, than in the control group (p<0.001). Human beta defensin-2 mRNA expression in the gingivitis group was lower than in the control group; however, the difference was statistically significant only in half of the gingivitis patients (p<0.001). Human beta defensin-2 mRNA levels were higher in some chronic periodontitis patients, but lower in the others when compared with the control group (p<0.001). Expression of the human beta defensin-2 gene increased in the aggressive periodontitis group relative to the control group.

CONCLUSION

This study suggests that human beta defensin-1 and -2 genes in the gingival epithelium show differential expression in patients with specific periodontal diseases, and aggressive and chronic periodontitis types demonstrate different gingival beta defensin-1 and -2 expression patterns.

Pattern of mRNA expression of beta-defensins in basal cell carcinoma

Background

Although the human β-defensins hBDs today seem to have diverse functional activities in innate antimicrobial immunity, a few reports also indicated an altered expression of these antimicrobial peptides (AMPs) in tissues of cancers such as oral squamous cell carcinoma. The present work was aimed on the study of hBD gene expression in basal cell carcinoma (BCC) which is the most common cancer in humans.

Methods

Twenty-two non-ulcerated BCCs (12 nodular type, 10 superficial type) have been analysed for the presence of hBD (1–3) mRNA by quantitative real-time RT-PCR. As controls, non-lesional skin specimens of BCC patients as well as samples of healthy subjects were assessed by RT-PCR.

Results

hBD-1 levels in healthy controls and non-lesional skin of BCC patients were significantly (P < 0.05) higher than the levels observed in tumour tissue. Moreover, BCCs showed significantly (P < 0.05) increased mRNA expression of hBD-2 as compared to controls. There was no significant (P > 0.05) difference between lesional mRNA levels for hBD-3 and those levels observed in controls. The mRNA expression of hBDs (1–3) found in nodular and superficial BCCs did not significantly (P > 0.05) differ.

Conclusion

The gene expression patterns of hBD-1 and hBD-2 are for the first time shown to be significantly altered in non-ulcerated BCCs as compared to intra-individual and inter-individual controls, respectively. The present findings may indicate that beside the antimicrobial activity of AMPs, hBDs may also play a role in the pathogenesis of BCC. However, functional and immunohistological studies investigating hBDs in patients with BCC are needed to confirm our data.

Antimicrobial peptides in the oral environment: expression and function in health and disease

The oral cavity is a unique environment in which antimicrobial peptides play a key role in maintaining health and may have future therapeutic applications. Present evidence suggests that alpha-defensins, beta-defensins, LL-37, histatin, and other antimicrobial peptides and proteins have distinct but overlapping roles in maintaining oral health and preventing bacterial, fungal, and viral adherence and infection. The expression of the inducible hBD-2 in normal oral epithelium, in contrast to other epithelia, and the apparent differential signaling in response to commensal and pathogenic organisms, provides new insights into innate immunity in this body site. Commensal bacteria are excellent inducers of hBD-2 in oral epithelial cells, suggesting that the commensal bacterial community acts in a manner to benefit the overall innate immune readiness of oral epithelia. This may have major significance for understanding host defense in the complex oral environment.

Statherin levels in saliva of patients with precancerous and cancerous lesions of the oral cavity: a preliminary report

OBJECTIVE

The aim of this study was to measure concentration of human salivary statherin in patients with oral cavity pathologies and salivary gland diseases.

SUBJECTS AND METHODS

Levels of statherin were analysed with High Performance Liquid Chromatography (HPLC) in following groups of subjects: group A: 24 patients with neoplastic diseases of salivary glands, group B: 13 patients with inflammatory lesions of salivary glands, group C: 13 patients with precancerous and cancerous lesions of the oral cavity excluding salivary gland tumors, group D: 20 healthy volunteers (control group).

RESULTS

Our preliminary data indicated a sensible reduction of the statherin level in the saliva of patients with precancerous and cancerous lesions of the oral cavity (group C) compared with the healthy subjects (group D). The statherin levels are not significantly reduced either in the inflammatory (group B) or in the salivary glands tumours (group A), compared with the healthy subjects (group D).

CONCLUSION

Statherin could play a protective effect in oral cavity in association with its other functions.

Effect of defensin peptides on eukaryotic cells: primary epithelial cells, fibroblasts and squamous cell carcinoma cell lines

BACKGROUND

Although the usefulness of the antimicrobial peptides known as defensins has been suggested against oral and skin infections, possible adverse effects of the defensins on the host should be understood before clinical applications can be contemplated.

OBJECTIVE

In the present study, we investigated how alpha-defensin (HNP-1) and beta-defensins (hBD-1, -2, -3) affect cells including primary epithelial cells, fibroblasts and squamous cell carcinoma cell lines, SCC-9 and KB.

METHOD

Cell proliferation was assessed by the direct cell counting and XTT assay.

RESULTS

We found that alpha-defensin promotes proliferation of the epithelial cells at low concentration but has a cytotoxic effect at high concentration. In contrast, beta-defensins have little effect on these cells at any concentration, suggesting that beta-defensins may have no adverse effects on the host.

CONCLUSION

Therefore, in terms of host response beta-defensins may be more suitable antimicrobial agents for clinical applications than alpha-defensins.

Identification of defensin alpha6 as a potential biomarker in colon adenocarcinoma

There is substantial interest in the identification of circulating human tumor-derived proteins in serum for the purposes of early cancer diagnosis. We have implemented an approach based on the analysis of microarray data for the identification of tumor proteins that may have utility as biomarkers in colon cancer. Expression analysis of microarray data obtained from a variety of 283 tumors and normal tissues revealed that defensin alpha6 was maximally expressed in colon cancer. These findings were corroborated by reverse transcription-PCR, in which the colon cancer cell lines LoVo, Caco2, HCT-15, SW480, and SW620 showed significantly higher levels of defensin alpha6 expression than did non-colon cancer cell lines. Moreover, our data were concordant with data obtained from the NCI, National Institutes of Health Cancer Genome Anatomy Project. To evaluate defensin alpha6 as a potential biomarker of colon cancer, a preliminary "training" set of serum from 91 healthy donors and 109 colon cancer patients was analyzed by enzyme-linked immunosorbent assay. The data pattern was confirmed by an independent set of 67 masked serum samples: 18 from healthy donors and 49 from colon cancer patients. This result yielded a sensitivity of 69.4% (95% CI 54.6-81.8), specificity of 83.3% (58.6-96.4), and positive predictive value of 91.9% (78.1-98.3). These findings justify a prospective assessment of serum defensin alpha6 protein as a screening tool for colon cancer.

Correlated expression of human beta defensin-1, -2 and -3 mRNAs in gingival tissues of young children

OBJECTIVE

Human beta-defensins (hBDs) are a group of antimicrobial peptides, expressed by the epithelial cells of many organs including gingival epithelium. The present study examined correlation between the gene expressions of hBD-1, -2, -3 mRNAs and the inflammatory cytokines in human gingival tissues.

STUDY DESIGN

The gingival tissues were obtained from surgical discards from 20 different patients (age range, 5-13 years). The expression levels of mRNAs were evaluated by quantitative RT-PCR with LightCycler. The mRNA expression levels were normalized with those of keratin 10 mRNA. The data were statistically analysed using Person's correlation coefficient.

RESULTS

The expression levels of hBD-1,-2 and -3 were significantly correlated with each other and also correlated with that of TNF-alpha.

CONCLUSIONS

The results indicate that the expression levels of hBDs vary from one individual to another.

Regulation of activities of NK cells and CD4 expression in T cells by human HNP-1, -2, and -3

Human neutrophil defensin alpha (HNP) is a group of cationic peptides of diverse physiological roles. Recent studies revealed the nature of HNPs as the dominant HLA-DR binding peptides on malignant cancer cells, which may block the major histocompatibility complex for antigen presentation. Here we show that HNPs may inhibit T cells by downregulating CD4 expression, a molecule of critical importance for T cell's interaction with the target cell. HNPs also inhibited tumor-cell-lysis activities of NK cells by downregulating CD16-CD56 expression. More importantly, HNPs were markedly elevated in 14 cancer tissues out of 15 self-paired human colorectal cancers and their adjacent noncancerous tissues. The subset compositions of HNPs extracted from cancer tissues and neutrophils were identical. Immunohistochemical studies indicated that HNPs mainly distributed in the infiltrated neutrophils in the interstitium. The elevated HNPs in cancer tissues may create a microenvironment unfavorable for adaptive immune reaction, implicating the cancer evasion.

Selective induction of human beta-defensin mRNAs by Actinobacillus actinomycetemcomitans in primary and immortalized oral epithelial cells

Human beta-defensin-2, and -3 (hBD-2, -3) are small inducible antimicrobial peptides involved in host defense. Actinobacillus actinomycetemcomitans, a gram-negative facultative anaerobe, is frequently associated with oral disease in humans. A. actinomycetemcomitans, strain JP2, was examined for its ability to modulate hBD-2 and -3 gene expression in normal human oral epithelial cells (NHOECs) and in OKF6/Tert cells, an immortalized cell line derived from human oral epithelial cells. Stimulation of both cell types by live bacteria, at a minimal bacteria/cell ratio of 500 : 1, resulted in increased hBD-3 gene expression. This was not evinced for hBD-2 in either cell type with live bacteria, even at bacteria/cell ratios exceeding 500 : 1. The increased hBD-3 gene expression was dependent upon viable bacteria, and not their lipopolysaccharides (LPS), since heat-killed A. actinomycetemcomitans did not induce hBD-3 transcript expression. The overall similarity between results obtained in OKF6/Tert cells and NHOECs suggest that the OKF6/Tert cell line may be a useful tool in the study of beta-defensin expression in oral epithelium.

Upregulation of human beta-defensin 2 peptide expression in oral lichen planus, leukoplakia and candidiasis. an immunohistochemical study

Human beta defensin 2 (hBD-2) is a major antimicrobial peptide that is produced by many types of epithelial cells, and is transcriptionally inducible by various proinflammatory agents, such as cytokines and bacteria. Although in vitro studies of the hBDs in oral epithelial cells have been well documented, only little is known about the in vivo pathological state of oral epithelium. We investigated the localization of hBD-2 peptide in tissue sections of oral lichen planus, leukoplakia, candidal leukoplakia and radicular cysts using immunohistochemistry. HBD-2 was stained in both the hyperkeratinized and the granular layers in cases of lichen planus with hyperkeratosis and leukoplakia. Expression in spinous and suprabasal layers was often strong in lichen planus. There were no significant differences in the number of S-100 positive dendritic cells between the widely stained areas and those with limited staining areas in lichen planus. In cases of candidal leukoplakia, the hyphae of candida were mainly detected on the surface of keratinization, which showed only negative or faint staining for hBD-2. These results suggest that hBD-2 is vigorously induced by lichen planus-related inflammation and that it plays an important role in protection from Candida albicans infection; however, it is not a strong chemotactic attractant for Langerhans cells in pathological conditions of oral epithelium.

Expression of MIP-3alpha/CCL20, a macrophage inflammatory protein in oral squamous cell carcinoma

We have examined the expression of MIP-3alpha/CCL20 in oral squamous cell carcinoma (SCC) in vivo and in vitro. In addition, we have investigated whether the expression of MIP-3alpha/CCL20 is regulated by bacterial infection and inflammatory cytokines. In order to determine the mRNA level of MIP-3alpha, quantitative reverse transcription-polymerase chain reaction (RT-PCR) was performed with LightCycler using the double-stranded DNA dye, SYBR Green I. Oral epithelial cells and six SCC cell lines (SCC-9, SAS, BSC-OF, HSC-4, HSC, Ca9-22) were found to express MIP-3alpha mRNA. The expression of MIP-3alpha was upregulated by infection with Actinobacillus actinomycetemcomitans and by stimulation with lipopolysaccharide and TNF-alpha. By in situ hybridization, the detectable MIP-3alpha expression in SCC was localized primarily at the epithelial pearls corresponding to the spinous layer. These results suggest that MIP-3alpha contributes to the oral immunoresponse to bacterial infection, and may be involved in the growth of SCC.

AN EXPERIMENTAL STUDY ON THE FEATURES OF PERI-IMPLANT EPITHELIUM: IMMUNOHISTOCHEMICAL AND ELECTRON-MICROSCOPIC OBSERVATIONS

The purpose of this study was to investigate the immunohistochemical and the ultrastructural features of the implant circumference epithelium of the beagle dog using various types of antibodies. The peri-implant epithelium was at an acute-angle from the gingival epithelium and was arranged in parallel to the implant surface. With immunohistochemical staining, the peri-implant epithelium was strongly positive for KL-1, and weakly positive for CK4, CK8 and CK19. These positive reactions for keratins and also for PCNA and BM-1 were similar to those seen in the oral mucosa. In the peri-implant epithelium, a plentitude of microvilli were observed at the periphery of cells at the implant sites, and bacteria were observed between the implant and the peri-implant epithelium without the formation of half desmosomes. There were many lipid-like vacuoles or lysosome-like granules. The intercellular space was wider than the junctional epithelium, and random migrations of large numbers of neutrophils could be seen. Taken together, the peri-implant epithelium is similar to that seen in the oral mucosa, and it is structurally different from the junctional epithelium.

Human alpha-defensins HNPs-1, -2, and -3 in renal cell carcinoma: influences on tumor cell proliferation

The alpha-defensins human neutrophil peptides (HNPs)-1, -2, and -3 have been described as cytotoxic peptides with restricted expression in neutrophils and in some lymphocytes. In this study we report that HNPs-1, -2, and -3 are also expressed in renal cell carcinomas (RCCs). Several RCC lines were found to express mRNA as well as the specific peptides of HNP-1, -2, and -3 demonstrated by reverse transcriptase-polymerase chain reaction, mass spectrometric, and flow cytometric analyses. At physiological concentrations HNPs-1, -2, and -3 stimulated cell proliferation of selected RCC lines in vitro but at high concentrations were cytotoxic for all RCC lines tested. As in RCC lines, alpha-defensins were also detected in vivo in malignant epithelial cells of 31 RCC tissues in addition to their expected presence in neutrophils. In most RCC cases randomly, patchy immunostaining of alpha-defensins on epithelial cells surrounding neutrophils was seen, but in six tumors of higher grade malignancy all tumor cells were diffusely stained. Cellular necrosis observed in RCC tissues in association with extensive patches of HNP-1, -2, and -3, seemed to be related to high concentrations of alpha-defensins. The in vitro and in vivo findings suggest that alpha-defensins are frequent peptide constituents of malignant epithelial cells in RCC with a possible direct influence on tumor proliferation.

Immunohistochemical study on expression of alpha-defensin and beta-defensin-2 in human buccal epithelia with candidiasis

OBJECTIVES AND DESIGN

It has been previously reported that alpha-defensin (HNPs) and beta-defensin-2 (HBD-2) peptides with antifungal and cytotoxic activities can be detected in oral carcinomas and the saliva of patients with oral carcinomas. The present study investigated the presence of HNPs and HBD-2 in oral epithelia with candidiasis.

MATERIALS AND METHODS

Tissue sections (4 microm) were prepared from biopsy and surgically removed specimens diagnosed as oral candidiasis (n = 10). The sections were examined immunohistochemically with antibodies directed against HNPs and HBD-2.

RESULTS

Tissue sections of oral candidiasis were immunostained with antidefensin antibodies. Neutrophils in the inflamed lamina propria were positively immunostained with anti-HNPs antibody. The cytoplasm of cells in the upper spinous layer, in the lower spinous layer and in the parakeratinized layer of buccal epithelia with candidiasis was immunostained intensely with anti-HBD-2 antibody. In contrast, the expression of HBD-2 in the normal spinous layer was much weaker than that in oral candidiasis. No signals of HNPs were found in normal buccal epithelium.

CONCLUSION

Buccal specimens from individuals with oral candidiasis show greater levels of expression of both HNPs and HBD-2. There might be a dual protection manner by defensins against fungal inflammation in infected buccal epithelia locally. Generally, HBD-2 signals have been found everywhere in the buccal epithelium; however, in an infected area, the signal intensity of HBD-2 has increased. HNPs signals have not been found in the normal buccal epithelium; however, HNPs signals have increased when the infection occurred.

Defensins -- innate immunity at the epithelial frontier

Physical barrier function was formerly believed to play the major role in mucosal protection against luminal bacteria. This view has now been challenged by the discovery of specialized molecules that possess antimicrobial activity. More than 100 peptides have been identified so far, and the number is still growing. These peptides are distributed widely and conserved throughout phylogeny. The epithelial expression of antimicrobial peptides is of particular interest as many pathogens adhere to epithelial surfaces and may eventually invade the host. This rapidly acting defence system of innate immunity is already engaged before adoptive immune interactions take place. These antimicrobial peptides consist of constitutive and inducible forms, potentiating this barrier function in terms of an inflammatory response. One important subgroup of antimicrobial peptides is the family of defensins, which are classified as alpha (alpha-) and beta (beta-) defensins. Eight different peptides with varying antimicrobial properties have been identified. They are distributed widely in humans, and organ-specific expression patterns have been observed. Homologous peptides have been found in other mammals, vertebrates, invertebrates, insects and plants. The identification of alpha-defensins and their murine counterparts, cryptdins, in the small intestine prompted intensive research into epithelial antimicrobial defence.