Leptin Stimulated Cell Proliferation Research Articles

Leptin induces leiomyoma cell proliferation and extracellular matrix deposition via JAK2/STAT3 and MAPK/ERK pathways

To investigate the molecular effects of leptin on uterine leiomyoma cells. Experimental study using invitro culture of immortalized human leiomyoma (HuLM) cells. Academic university center. Women with uterine fibroids who underwent a hysterectomy or myomectomy. Administration of human recombinant leptin to the media of cultured HuLM cells separately or in combination with pharmacologic Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) or mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) inhibitors. We examined HuLM tissues and cells for the expression of the leptin receptor, termed OB-R. Cellular proliferation was measured at 6, 24, and 48 hours using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide assay. Protein expression levels of proliferating cell nuclear antigen, collagen 1, phosphorylated STAT3/total STAT3, and phosphorylated ERK1/2 and total ERK1/2 were quantified using immunoblotting. Pharmacologic inhibitors were employed to further assess the role of the JAK2/STAT3 and MAPK/ERK pathways in the proliferative response. The presence of OB-R was confirmed in clinical leiomyoma and myometrial tissue obtained from 3 separate human subjects using immunofluorescence staining, and the expression of OB-R in HuLM cells was identified using immunoblotting. There was no significant difference in the expression of the leptin receptor in the myometrium compared with that in the leiomyoma tissue. Leptin stimulated cell proliferation and extracellular matrix (ECM) deposition at 24 hours after treatment. Pretreatment with a JAK2/STAT3 inhibitor attenuated ECM deposition, and pretreatment with a MAPK/ERK inhibitor significantly decreased leptin's stimulatory effect on cell proliferation and ECM deposition. Leptin induces a proliferative response and ECM deposition in HuLM cells. These findings suggest that leptin, acting through the JAK2/STAT3 and MAPK/ERK pathways, is involved in the development of uterine leiomyomas, which may partly explain their increased incidence in obese women.

Diallyl Trisulfide Inhibits Leptin-induced Oncogenic Signaling in Human Breast Cancer Cells but Fails to Prevent Chemically-induced Luminal-type Cancer in Rats.

Previous studies have demonstrated inhibitory effect of garlic component diallyl trisulfide (DATS) on growth of breast cancer cells in vitro and in vivo. This study investigated the effect of DATS on oncogenic signaling regulated by leptin, which plays an important role in breast carcinogenesis. Leptin-induced phosphorylation and nuclear translocation of STAT3 was inhibited significantly in the presence of DATS in MCF-7 (a luminal-type human breast cancer cell line) and MDA-MB-231 (a basal-like human breast cancer cell line). Leptin-stimulated cell proliferation, clonogenic cell survival, and migration and/or invasion ability in MCF-7 and/or MDA-MB-231 cells were also suppressed by DATS treatment. DATS exposure resulted in inhibition of leptin-stimulated expression of protein and/or mRNA levels of Bcl-2, Bcl-xL, Cyclin D1, vascular endothelial growth factor, and matrix metalloproteinase-2. Western blotting revealed a decrease in protein levels of phosphorylated STAT3 in breast cancer xenografts from DATS-treated mice when compared to controls in vivo. However, the incidence of N-methyl-N-nitrosourea-induced luminal-type breast cancer development in rats was not affected by oral administration of 5 mg/kg or 25 mg/kg DATS. The present study reveals that oncogenic signaling induced by leptin is inhibited in the presence of DATS but higher doses of this phytochemical may be required to achieve chemopreventive activity.

Abstract 299: Modulation of the leptin receptor in pancreatic cancer cells mediates tumor growth

Abstract Background: Pancreatic cancer is the fourth leading cause of cancer death with a five year survival rate around 5%, which has not changed in 30 years. Obesity and increased abdominal adipose tissue independently correlate with an increased relative risk for the development of pancreatic cancer. These conditions have been associated with altered levels of adipokines, or adipose secreted cytokines. Circulating serum levels of the adipokine leptin are increasesddramatically in obese patients as well as in high fat diet induced obese mice. Leptin has been shown to induce oncogenic signaling in breast and prostate cancer. We have previously shown an increase in orthotopic pancreatic tumor size in high fat diet induced obese mice compared with regular diet control mice. We hypothesize that leptin signaling mediates pancreatic tumorigenesis. Methods: Leptin receptor status was determined in human as well as murine pancreatic cell lines. Leptin stimulated cell proliferation was determined using a modified BrdU assay. Leptin receptor levels were knocked down in human and murine pancreatic tumor cells using a shRNAmir approach. Leptin receptor shRNA Panc02 knockdown cells were injected orthotopically into the pancreas of C57/Bl6J mice on regular or high fat diet to determine the contribution of leptin to pancreatic tumor growth. Results: We have detected the long form of the leptin receptor in five human and four murine pancreatic cancer cell lines. In vitro administration of leptin stimulated proliferation of Panc1 and CFPAC1 cell lines, which was abrogated with co-incubation of a leptin antagonist. To better understand the mechanism of leptin-mediated signaling, we studied downstream targets and identified a significant increase in phosphorylation of STAT3 in Panc1, BXPC3 and CFPAC1 cell lines after leptin treatment. Orhtotopic injection of leptin receptor shRNA Panc02 cells into normal and obese mice showed a markedly diminished tumor growth in obese mice when compared to the nonsilencing control Panc02 cell growth in obese mice. Conclusion: These results implicate leptin as a mediator of pancreatic tumorigenesis and suggest that leptin activation is mediated in part through STAT3 signaling. Knockdown of the leptin receptor results in inhibition of high fat diet associated tumor growth in vivo. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 299. doi:1538-7445.AM2012-299

Acrp30 inhibits leptin-induced metastasis by downregulating the JAK/STAT3 pathway via AMPK activation in aggressive SPEC-2 endometrial cancer cells

Obesity is a well-established risk factor for endometrial cancer, due in part to the adipokines generated by adipose tissue, such as adiponectin (also known as Acrp30) and leptin, which are associated with many endocrine-related cancers. Recent reports suggested that Acrp30 inhibits leptin-stimulated cell proliferation in HEC-1A and RL95-2 endometrial cancer cell lines, and that the serum leptin/Acrp30 ratio plays an important role in endometrial cancer development. We explored whether Acrp30 could reverse the leptin-induced metastasis phenotype in the SPEC-2 endometrial cancer cell line. Transcripts for Acrp30 receptors (AdipoR1 and AdipoR2) and leptin receptor (Ob-Rb) were detected by quantitative real-time RT-PCR (qRT-PCR) in six endometrial cancer cell lines. Leptin (1µg/ml) treatment stimulated SPEC-2 cell proliferation by inducing cell cycle arrest and apoptosis, while Acrp30 (10µg/ml) treatment inhibited the growth of SPEC-2 cells. Importantly, Acrp30 was able to inhibit leptin-induced SPEC-2 cell proliferation. Leptin promoted SPEC-2 cell invasion in a Matrigel transwell assay, while Acrp30 partly suppressed the invasion stimulated by leptin. To investigate the molecular mechanism underlying this phenomenon, we monitored the AMPK and JAK/STAT3 signaling pathways by western blotting and cell immunofluorescence. Acrp30 reduced leptin-induced STAT3 phosphorylation and nuclear translocation via activation of the MAPK pathway. AG490 (JAK/STAT3 inhibitor) reduced MMP-2 and MMP-9 protein levels in cells treated with leptin, while IL-6 (JAK/STAT3 stimulator) and Compound C (AMPK inhibitor) elevated MMP-2 and MMP-9 protein levels in cells treated with Acrp30. In conclusion, we demonstrated that Acrp30 effectively reversed the invasion stimulated by leptin, and AMPK and JAK/STAT3 pathways mediated the invasive phenotype of SPEC-2 cells.

Leptin receptor expression and its association with PI3K/AKT signaling pathway in diffuse large B-cell lymphoma

We investigated the role of the leptin receptor (Ob-R) and its relationship with PI3K/AKT activation in diffuse large B-cell lymphoma (DLBCL) clinical samples followed by in vitro studies using a panel of CRC cell lines. Leptin exerts its physiological action through its receptor Ob-R. Overexpression of Ob-R has been implicated in the pathogenesis of a variety of malignancies; however, its role in DLBCL has not been investigated. Using immunohistochemistry on a large cohort of DLBCL samples in a tissue microarray format, Ob-R immunostaining was detected in 86/216 (39.8%). Ob-R overexpression was associated with the catalytic subunit p110 of PI3K (p = 0.0283), activated AKT (p = 0.0003), and antiapoptotic marker XIAP (p = 0.0008) expression. In in vitro analysis using DLBCL cell lines, our data showed that leptin stimulated cell proliferation and inhibited apoptosis via activation of the PI3K/AKT signaling pathway. Pretreatment of DLBCL cells with Ob-R specific small interference RNA or inactivation of PI3K/AKT activity by LY294002 abolished these responses. Altogether, these data suggest that leptin plays a critical role in DLBCL pathogesis through the P13K/AKT pathway via Ob-R.

Leptin-R and its association with PI3K/AKT signaling pathway in papillary thyroid carcinoma

The putative role of leptin and its receptor (Ob-R) in the pathogenesis of various primary human malignancies has been reported; however, their role in papillary thyroid cancer (PTC) has not yet been evaluated. We investigated the role of Ob-R in a large tissue microarray cohort of PTC followed by in vitro studies using a panel of PTC cell lines. Ob-R overexpression was seen in 80% PTCs and was significantly associated with poor disease-free survival (P=0.0235). PTCs that overexpressed Ob-R showed a aggressive phenotype characterized by older age, extrathyroid extension, larger tumor size, nodal metastasis, advanced stage, tall cell variant histological subtype, and a poor disease-free survival (P=0.0005, P=0.0006, P=0.0398, P=0.0004, P=0.0111, P=0.0003, and P=0.0235 respectively). However, Ob-R expression was not an independent prognostic marker to predict disease-free survival in multivariate analysis. PTCs with overexpression of Ob-R showed a significant direct association with overexpression of XIAP (P<0.0001) and Bcl-XL (P<0.0001). In vitro analysis showed that leptin stimulated cell proliferation and inhibited apoptosis via activation of phosphatidylinisitol 3' kinase (PI3K)/protein kinase B (AKT) signaling pathway. Inhibition of PI3K activity by its inhibitor LY294002 abrogated leptin-mediated PI3K/AKT signaling. Gene silencing of Ob-R in PTC cells resulted in downregulation of phospho-AKT, Bcl-XL, and XIAP expression suggesting that leptin-mediated pathogenesis of PTC occurs via involvement of these downstream targets. Altogether, these data show that leptin plays an important role in PTC pathogenesis through PI3K/AKT pathway via Ob-R and is a potential prognostic marker associated with an aggressive phenotype and poor disease-free survival.

Abstract A19: Enhanced leptin receptor expression identifies an aggressive subset of Middle Eastern papillary thyroid cancer

Abstract The putative role of leptin (Ob) and its receptor (Ob-R) in the pathogenesis of various primary human malignancies has been investigated in recent studies. However, the role of leptin and leptin receptor (Ob-R) in papillary thyroid cancer (PTC) has not yet been evaluated. In this study we investigated role of Ob-R in a large tissue microarray cohort of PTC followed by in vitro studies using a panel of PTC cell lines. Ob-R overexpression was seen in 80% PTCs and was significantly associated with poor disease free survival (p=0.0235). PTCs that overexpressed Ob-R showed a aggressive phenotype characterized by older age, extrathyroid extension, larger tumor size, nodal metastasis, advanced stage and tall cell variant histological subtype (p=0.0005, p=0.0006, p=0.0398, p= 0.0004, p=0.0111 and p=0.0003 respectively). Further PTCs with overexpression of Ob-R showed a significant direct association with overexpression of leptin (p=0.0004), XIAP (p&amp;lt;0.0001) and BCL-XL (p&amp;lt;0.0001). In vitro analysis showed that leptin stimulated cell proliferation and inhibited apoptosis via activation of phosphatidylinisitol 3-kinase (PI3K)/AKT signalling pathway. Inhibition of PI3K activity by LY294002, a specific inhibitor of PI3K kinase abrogated leptin-mediated PI3K/AKT signalling. Gene silencing of Ob-R with Ob-R siRNA in PTC cells resulted in down regulation of phospho-AKT, Bcl-XL and XIAP expression suggesting that leptin mediated pathogenesis of PTC occur via involvement of these downstream targets. Altogether these data suggest that leptin plays a critical role in PTC pathogenesis through PI3K/AKT pathway via Ob-R and is a potential prognostic marker associated with an aggressive phenotype and poor disease free survival. Citation Information: Cancer Res 2009;69(23 Suppl):A19.

Overexpression of leptin receptor predicts an unfavorable outcome in Middle Eastern ovarian cancer

BackgroundRecent epidemiological studies have suggested that obesity is associated with ovarian cancer. Obesity hormone leptin and its receptor (Ob-R) contribute to tumor development by enhancing cell growth and survival. This study was design to investigate the prevalence of leptin and Ob-R in Middle Eastern epithelial ovarian cancer (EOC) and to analyze the role of leptin and the mechanisms under its action in EOC tissue sample and cell lines.MethodsThe expression of leptin and Ob-R was examined by immunohistochemistry in a tissue microarray of 156 EOC samples. Proliferation of EOC cells in response to leptin was assessed by MTT assays, and its anti-apoptotic effects were determined by flow cytometry. Effect of leptin on PI3K/AKT signaling pathway was further determined by western blotting.ResultsIn clinical samples, Ob-R overexpression was seen in 59.2% EOCs and was significantly associated with poor progression free survival (p = 0.0032). Furthermore, Ob-R expression was associated with anti apoptotic proteins Bcl-XL (p = 0.0035) and XIAP (p = 0.0001). In vitro analysis using EOC cell lines showed that leptin stimulated cell proliferation and inhibits apoptosis via activation of PI3K/AKT signaling pathway. Inhibition of PI3K activity by LY294002, a specific inhibitor of PI3-kinase abrogated leptin mediated PI3K/AKT signaling. Gene silencing of Ob-R with Ob-R siRNA in EOC cells resulted in down regulation of phospho-AKT and its down stream targets.ConclusionOur findings have potential clinical implication for EOC development and progression.

Opposing effects of chronic stress and leptin on adult hippocampal neurogenesis

Adult hippocampal neurogenesis has been implicated in the therapeutic mechanism of antidepressants. Here we show that the adipocyte‐derived peptide leptin promotes neurogenesis in the adult hippocampus under basal conditions and reverses chronic stress‐induced impairment of neurogenesis. Chronic administration of leptin increased cell proliferation, but had no significant effect on differentiation and survival of newly proliferated cells in the dentate gyrus of the hippocampus. Analysis of signal transduction pathways in cultured hippocampal neural progenitor cells revealed that leptin stimulated phosphorylation of Akt and STAT3, but not Erk1/2. Pretreating the cells with specific inhibitors of Akt or STAT3 attenuated leptin‐stimulated cell proliferation in a dose‐dependent manner, suggesting that these pathways may mediate the effects of leptin on neurogenesis. In a chronic stress model of depression, we demonstrated that neurogenesis was suppressed by chronic stress, which was accompanied by depression‐like behavioral deficits. Chronic leptin treatment was able to reverse the chronic stress‐induced suppression of neurogenesis and behavioral deficits. Taken together, these results support an important role for leptin in adult hippocampal neurogenesis under both physiological and pathological conditions.

Leptin induces functional activation of cyclooxygenase‐2 through JAK2/STAT3, MAPK/ERK, and PI3K/AKT pathways in human endometrial cancer cells

Hyperleptinemia is a common feature of obese women who have a higher risk of endometrial cancer than women with normal weights, and epidemiologic studies have suggested a correlation between obesity and endometrial carcinoma. Therefore, understanding of the molecular mechanism involved in leptin signaling transduction is important in endometrial cancer prevention and treatment. In this study, both isoforms of the leptin receptor (Ob-R), the long form (Ob-Rb) and short form (Ob-Ra), were detected as being expressed in six endometrial cancer cell lines with various differentiation status by western blotting, and Ob-Ra was found to be more abundant than Ob-Rb in these cells. Moreover, the expressions of both isoforms were inversely correlated with histoprognostic grading. We also showed that leptin stimulated cell proliferation and induced activations of signal transducers and activators of transcription 3 (STAT3), extracellular signal-regulated kinase (ERK1/2), AKT, and cyclooxygenase (COX)-2 in endometrial cancer cells dose-dependently by [(3)H] thymidine incorporation assay and western blotting. Leptin-stimulation resulted in increased expression of COX-2 mRNA and prostaglandin E2 (PGE2) production of endometrial cancer cells by reverse transcription-polymerase chain reaction and enzyme immunoassay, respectively, which was effectively blocked by pharmacological inhibitors of Janus tyrosine kinase 2 (JAK2), AG490; of mitogen-activated protein kinase (MAPK) kinase, U0126; of phosphatidylinositol 3-kinase (PI3K), LY294002; and of COX-2, NS398. These results suggest that leptin promotes cell proliferation of endometrial cancer cells via the aforementioned multiple signal-transduction pathways. Leptin-induced functional activation of COX-2 is JAK2/STAT3-, MAPK/ERK-, and PI3K/AKT-dependent, indicating that COX-2 may be a critical factor of endometrial carcinogenesis in obesity.

Leptin Stimulates Parathyroid Hormone Related Peptide Expression in the Endochondral Growth Plate

We have previously shown that growth plate chondrocytes expressed the long form of leptin receptor, and that within the growth plate, leptin stimulated cell proliferation and differentiation and epiphyseal growth in a balanced manner. These three cell processes are known to be regulated by the interactions of parathyroid hormone-related peptide (PTHrP) and Indian hedgehog (Ihh) protein. The aim of the present study was to examine the effect of leptin on the PTHrP/Ihh feedback loop. The effect of leptin was investigated in vivo in pair-fed experiments in ICR mice, and ex vivo in mandibular condyle explants incubated with leptin. Immunohistochemistry and in situ hybridization showed that in the pair-fed in vivo system as well as in the organ culture, leptin increased the level of PTHrP and reduced that of Ihh. Leptin may affect chondrocyte proliferation and differentiation by activating the PTHrP/Ihh growth-restraining feedback loop in the postnatal growth plate.

Defining the mechanisms by which leptin stimulates proliferation of ovarian cancer cells

15017 Background: Ovarian cancer (OvCa) ranks fourth as the cause of death related to cancer in women in the U.S. The vast majority (&gt;90%) of OvCa originates from the ovarian surface epithelium. There is sufficient evidence to suggest that hormones, especially estrogen, may be involved in the etiopathogenesis of epithelial OvCa. Recent studies indicate that leptin participates either directly or indirectly to promote carcinogenesis in both breast and endometrial cancers. Furthermore it has been proposed that leptin may elicit its action via an estrogen related pathway. Leptin can stimulate proliferation of some OvCa cell lines and has been implicated as a potential biomarker for OvCa. However the mechanism(s) by which leptin contributes to the growth of OvCa has yet to be defined. We hypothesize that leptin’s effect will be mediated in part by estrogen receptor (ER) pathways. Methods: Three epithelial OvCa cell lines (IGROV1, OVCAR5 and TOV21G) and one benign human ovarian surface epithelial cell line (HOSE) were evaluated. Enzyme linked immunosorbent assay (ELISA) and Western blotting were used to assess leptin and leptin receptor (ObR), respectively. Leptin (0.06 nM–6.25 nM) induced effects on cell proliferation were assessed in the presence or absence of an aromatase enzyme inhibitor (Anastrozole) or the ER antagonist (ICI182780). Further, we explored leptin-induced effects on ERα promoter activity as evidenced by change in fluorescence via a dual luciferase promoter reporter. All experiments were conducted in triplicate. All data were subjected to ANOVA followed by Tukey’s post hoc test (p &lt; 0.05). Results: All ovarian cell lines expressed ObR; whereas, no measurable amounts of leptin were detected in conditioned media. Leptin stimulated cell proliferation in both the benign and malignant lines. Leptin-induced cell proliferation was inhibited by Anastrozole and ICI182780. Furthermore, leptin stimulated luciferase activity of the ERα promoter/reporter. Conclusions: Leptin promotes proliferation of benign and malignant ovarian epithelial cells and appears to be mediated, at least in part, via aromatase and ER which may have therapeutic implications. This work was supported by the Vincent Memorial Hospital, SG Komen Foundation and the Advanced Medical Research Foundation. No significant financial relationships to disclose.

Direct actions of leptin on bone remodeling.

From the time of its original description almost a decade ago [1] leptin was regarded as a hormone originating in the adipocyte whose primary target was within the central nervous system. There, it regulates appetite and reproductive function. It has now become clear that leptin receptors are much more widely distributed than just the hypothalamus, and the skeleton has emerged as an important site of action of leptin. This is suggested by the demonstration of the signalling form of the leptin receptor in human osteoblasts [2–4], rat osteoblasts [5, 6], human chondrocytes [6], porcine chondrocytes [2], human mesenchymal stem cells undergoing osteogenic differentiation [7], and in osteoblastic and chondrocytic cell lines [5, 8]. Consistent with this receptor data, there is now abundant evidence indicating that leptin directly promotes the differentiation and growth of cells of the osteoblast lineage. Thomas et al. [9] found that leptin promoted differentiation of a human marrow stromal cell line into an osteoblast phenotype, and that it increased synthesis of bone matrix proteins, such as type I collagen and osteocalcin, in these cells. Similar findings have been reported by Gordeladze et al. [10] in studies of primary human osteoblasts, in which they also found that leptin reduced apoptosis and increased formation of mineralized bone nodules. Iwaniec et al. [11] have reported increased numbers of mineralized bone nodules in primary osteoblast cultures, and Reseland et al. [12] demonstrated this with both primary human osteoblast cultures and in osteosarcoma cell lines. We have found that low concentrations of leptin (>10 M) increase proliferation of isolated fetal rat osteoblasts to an extent comparable to that of IGF1 [6]. Thus, there is agreement across a range of in vitro models that leptin is anabolic to osteoblasts. There is also evidence that leptin directly regulates osteoclast development. Holloway et al. [13] have shown that leptin inhibits osteoclast generation from human peripheral blood mononuclear cells by reducing production of RANK in mononuclear cells. These findings are complemented by the report of Burguera et al. [14] that leptin increases osteoprotegerin levels and decreases RANK-ligand levels in human marrow stromal cells. Leptin (‡10 M) also inhibits osteoclastogenesis in mouse bone marrow cultures [6]. The effects of leptin on osteoclasts could be contributed to by its stimulation of the secretion of interleukin-1 receptor antagonist from monocytic and lymphocytic cells, which will reduce osteoclast recruitment [15, 16]. These in vitro findings of leptin effects on osteoclasts explain the clinical observations of an inverse relationship between serum leptin concentrations and bone resorption markers in human fetuses [17] and in postmenopausal women [18]. Thus, there is a consistent body of evidence suggesting that leptin will impact positively on bone density as a result of its dual effects on bone formation and resorption. Leptin may also impact on skeletal size since it acts on chondrocytes. We have demonstrated the presence of the leptin receptor in chondrocytes from human articular cartilage, and that proliferation of ovine and canine chondrocytes is promoted by leptin [6]. Systemic administration of leptin to adult mice increases the thickness of their growth plates [6]. Maor et al. [19] have shown specific binding sites for leptin in the chondrocyte cell population of skeletal growth centers in the mouse mandibular condyle. Leptin stimulated cell proliferation and increased the width of the chondroprogenitor zone in this model. These findings are reflected in the reduced femoral length of both the leptin-deficient mouse (Fig. 1) [2] and the leptin-resistant rat [20]. The positive effect of leptin on skeletal size suggests that this hormone may be a contributor to the increases in stature of successive generations of humans that has been observed over the last century or more [21]. As nutrition has improved, leptin concentrations may have increased with a consequent increase in growth and adult height. The final integration of the direct effects of leptin on bone cells seen in vitro occurs in at least three different ways. One is in human studies of the relationships between leptin and bone density. Circulating leptin conCorrespondence to: I. R. Reid; E-mail: i.reid@auckland.ac.nz Calcif Tissue Int (2004) 74:313–316 DOI: 10.1007/s00223-002-0015-z Calcified Tissue International

Leptin stimulates esophageal adenocarcinoma growth by nonapoptotic mechanisms

Background Leptin is a hormone primarily produced by adipocytes and serum leptin is elevated in obese persons. One risk factor associated with adenocarcinoma of the esophagus is obesity. We hypothesized that leptin would have stimulatory effects on esophageal adenocarcinoma and alter apoptosis in vitro. Methods Barrett's esophageal adenocarcinoma cells (BIC-1 and SEG-1) were cultured with human recombinant leptin (80 ng/mL) for 24 hours. Cell growth was determined by MTT assay. Apoptosis and necrosis was measured after 16 hours of treatment with leptin using a Cell Death Kit. Results Exogenous leptin stimulated cell proliferation in both cell lines. No changes in apoptosis or necrosis resulted between control and leptin-treated groups. Conclusions We have shown that leptin increases the proliferation of human esophageal adenocarcinoma, but does not alter cell apoptosis or necrosis. The data suggest that leptin stimulates esophageal adenocarcinoma growth by nonapoptotic mechanisms. Leptin antagonism may have potential efficacy in esophageal cancer therapy.