Metastasis Suppressor Gene KiSS-1 Research Articles

Increased serum levels of KiSS1-derived peptides in non-small cell lung cancer patient liquid biopsies and biological relevance

BackgroundThe secreted products of the metastasis suppressor gene KiSS1 may represent useful biomarkers in non-small cell lung cancer (NSCLC) but their levels in patients have remained poorly investigated. We previously found that forced expression of KiSS1 decreased the invasive capability of NSCLC drug-resistant cells and a pro-apoptotic role for KiSS1 has been proposed in head and neck cancer. Thus, we designed a translational investigation including a pilot study to analyze KiSS1 levels in liquid biopsies, and in vitro experiments to explore the biological relevance of KiSS1 modulation.MethodsKiSS1-derived peptide levels in liquid biopsies from 60 NSCLC patients were assayed by ELISA. Preclinical experiments were carried out using quantitative real time polymerase chain reaction (qRT-PCR), ELISA, annexin V-binding and caspase activation assays.Results We compared KiSS1 release in 3 different matrices (serum, plasma and urine) and the highest levels were detectable in serum (range, 0–4.5 ng/mL). We observed increased levels of seric KiSS1 in NSCLC patients as compared to healthy donors. KiSS1 serum concentrations, after surgical procedure and/or adjuvant therapy. We observed differences among disease stages in urine samples. In preclinical models, KiSS1 mRNA levels were increased by short term exposure to azacytidine, enhanced KiSS1 release was induced by the combination of azacytidine and cisplatin and KiSS1-derived peptides enhanced cisplatin-induced apoptosis. KiSS1 increase was observed upon exposure neurons-enriched cultures to tumor cell conditioned medium.ConclusionsOur results showing a peculiar modulation of KiSS1 levels in liquid biopsies of NSCLC patients and a regulation of cisplatin-induced apoptosis by KiSS1-derived peptides support an involvement of KiSS1 in cell response to treatment and highlight its promising features as a potential biomarker in NSCLC.

Abstract 973: Comparative single cell transcriptome profiling of primary tumors, CTCs and metastatic sites from a bladder cancer PDX model

Abstract Background: A PDX bladder cancer model, BL0293-F563, spontaneously metastasizes to the liver and bone, and sheds high numbers of circulating tumor cells (CTCs). This PDX model provides a unique opportunity to explore the relationships between primary tumors, CTCs, and metastases. Methods: BL0293-F563 tumors (available from the NCI Patient-Derived Models Repository [https://pdmr.cancer.gov/] and originally developed by Jackson Laboratories) were implanted into NSG mice, and primary tumors, metastatic nodules in the liver, and blood were collected at maximal allowable tumor burden. Tumor tissue was dissociated using Miltenyi Tumor Dissociation Kit with OctoDissociator, and Human CTCs were enriched from mouse blood through negative selection with anti-mouse CD45 and anti-mouse MHC-1 magnetic beads. Single cell sequencing was done using 10X Genomics 3’ gene expression assay v3.1. Data processing and analysis was done using 10X Genomics’ Cell Ranger pipeline, Seurat, and cNMF. Results: single cell RNAseq data from primary tumors, CTCs, and metastases from 9 mice were aggregated into a single dataset, and cells were classified into 17 clusters using Seurat FindNeighbors. All clusters contained cells from multiple sites (primary tumor, CTCs, metastases), but three clusters were enriched in CTCs and one cluster was composed of mostly primary tumor cells. All clusters exhibited epithelial-like gene expression signature scores, suggesting that CTC shedding was occurring without prominent epithelial-mesenchymal transition. CTC-enriched clusters showed elevated expression of RHO pathway genes, implicating ameboid-like migration in CTC shedding in this PDX model. Consistent with expected differences in oxygenation states, CTC-enriched clusters exhibited a lower hypoxia gene expression score than primary tumor and metastasis-enriched clusters. CTC-enriched clusters also showed higher expression of oxidative phosphorylation genes, suggesting metabolic differences between CTCs and cells from other sites. Additionally, two of three CTC-enriched clusters had elevated expression of mitosis-associated genes, indicating that at least some subpopulations of CTCs are actively cycling. A metastasis suppressor gene KISS1 was expressed in a subset of primary tumor cells but undetectable in CTCs, suggesting that KISS1 expression loss occurs before CTC shedding. Conclusions: Utilizing single cell gene expression profiling, we have linked the gene expression profile of CTCs to specific cell subpopulations in primary tumors and metastases. We show that CTC-enriched cell clusters appear to maintain an epithelial phenotype. Subpopulations of CTC cells exhibit enrichment of motility-associated transcripts and features of active cell cycling. Our results implicate a known metastasis suppressor gene KISS1 in CTC shedding and metastatic dissemination in this PDX model. Citation Format: Tomas Vilimas, Brandie Fullmer, Alyssa Chapman, Rini Pauly, Ting-Chia Chang, Li Chen, Biswajit Das, Chris Karlovich, Yvonne Evrard, Melinda Hollingshead, Howard Stotler, Michelle Ahalt-Gottholm, Tara Grinnage-Pulley, Mickey Williams, James H. Doroshow. Comparative single cell transcriptome profiling of primary tumors, CTCs and metastatic sites from a bladder cancer PDX model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 973.

Reversibility and safety of KISS1 metastasis suppressor gene vaccine in immunocastration of ram lambs.

ObjectiveThe aim of this study was to investigate the reversibility and safety of KISS1 metastasis suppressor (KISS1) gene vaccine in immunocastration.MethodsSix eight-week old ram lambs were randomly divided into vaccinated and control groups. The vaccine (1 mg/ram lamb) was injected at weeks 0, 3, and 6 of the study. Blood samples were collected from the jugular vein before primary immunization and at weeks 2, 4, 6, 10, 14, 22, and 30 after primary immunization. All ram lambs were slaughtered at 38 weeks of age, and samples were collected.ResultsThe specific anti-KISS1 antibody titers in vaccinated animals were significantly higher and the serum testosterone level was significantly lower than those in the control groups from week 4 to 14 after primary immunization (p<0.05). No significant difference was observed at weeks 22 and 30 after the primary immunization. Similar results were also found for scrotal circumference, testicular weight, length, breadth, and spermatogenesis in seminiferous tubules in week 30 after primary immunization. KS (KISS1-hepatitis B surface antigen S) fusion fragment of KISS1 gene vaccine was not detected in host cell genomic DNA of 9 tissues of the vaccinated ram lambs by polymerase chain reaction.ConclusionThe effects of KISS1 gene vaccine in immunocastration were reversible and no integration events were recorded.

The metastasis suppressor gene KISS-1 regulates osteosarcoma apoptosis and autophagy processes.

The expression of the metastasis suppressor gene KISS-1 in osteosarcoma cells during apoptosis and autophagy was evaluated. MG-63 osteosarcoma cells were transfected with either KISS-1 overexpression or KISS-1 knockdown expression vector in vitro, and compared with cell lines transfected with empty vector. After 12, 24, 48 and 72 h of cell culture, the cell proliferation was examined. The MTT method was used to detect apoptosis by flow cytometry, and the mRNA levels of apoptosis and autophagy markers caspase-3, Bcl-2, Bax, LC3 and Beclin1 were assessed by RT-PCR. Our results showed that cells in the control and low expression group kept proliferating during the cell culture period of 72 h, while the cells in the overexpression group progressively decreased in number. Also, the proliferation rate of the low expression group was significantly higher than that of the control group. The relative mRNA expression levels of caspase-3 and Bax mRNA in the control and low expression group showed no change (the expression was lowest in the low expression group). Moreover, the mRNA level of Bcl-2 increased in both cell groups. The mRNA expression levels of caspase-3 and Bax in the overexpression group were increased, and the level of Bcl-2 was reduced significantly. At the same time, the relative expression level of LC3 and Beclin1 mRNA in the control and low expression groups remained the same, and that of the overexpression group increased. The mRNA levels of LC3 and Beclin1 in the overexpression group were the highest, and that of the low expression group the lowest. The differences were statistically significant (P<0.05). Based on these results, we showed that KISS-1 inhibited the proliferation of osteosarcoma in vitro, probably by accelerating the processes of apoptosis and autophagy in the cells.

Elevated placental expression at the maternal-fetal interface but diminished maternal circulatory kisspeptin in preeclamptic pregnancies.

To investigate the placental mRNA and protein expression of metastasis suppressor gene Kiss-1 and the transcript expression of its receptor GPR-54 across the maternal-fetal interface of healthy and preeclamptic pregnancies. To furthermore compare placental tissue kisspeptin expression to circulatory kisspeptin levels in these pregnancies. Secondary and Tertiary Hospital Setting in Cape Town, South Africa. Patients with and without preeclampsia undergoing elective caesarean delivery. The placenta, placental bed and decidua parietalis as well as maternal and cord blood in both healthy and preeclamptic pregnancies were simultaneously sampled at elective caesarean delivery. RT-PCR was utilised to determine mRNA expression while immunohistochemistry was employed to investigate protein expression in maternal-fetal tissues. Circulating maternal and cord serum kisspeptin concentrations were determined using ELISA. Maternal-fetal tissue mRNA expression of Kiss-1 and GPR-54 as well as maternal/cord serum kisspeptin concentrations in healthy and preeclamptic pregnancies. There was high placental kisspeptin expression but low circulating serum kisspeptin levels in pregnancies complicated by preeclampsia. Kiss-1 mRNA and protein expression was minimal in the maternal tissues (placental bed and decidua parietalis) of both healthy and preeclamptic pregnancies. No difference was found in Kiss-1 receptor (GPR-54) mRNA expression across maternal-fetal tissues of healthy and preeclamptic pregnancies. Increased placental kisspeptin expression is consistent with reduced trophoblast invasiveness and may represent a molecular mechanism that explains the development of preeclampsia. Decreased circulating kisspeptin concentration has the potential to be utilised as a marker for placental dysfunction.

P-0008 - Effect on the Proliferation, Invasion and Metastasis of Gastric Cancer Cells Transfected by Metastasis Suppressor Gene Kiss-1 in Vivo

P-0008 - Effect on the Proliferation, Invasion and Metastasis of Gastric Cancer Cells Transfected by Metastasis Suppressor Gene Kiss-1 in Vivo

Loss of the metastasis suppressor gene KiSS1 is associated with lymph node metastasis and poor prognosis in human colorectal cancer

Cancer research is currently focused on blocking the metastatic process at its early steps. Some particularly attractive targets are metastasis suppressor genes, which control cancer cell dissemination. The aim of this study was to clarify the relationship between the expression of KiSS1, a metastasis suppressor gene, and disease progression in colorectal cancer patients. One-hundred and seventy-five patients who underwent surgery for colorectal cancer were enrolled in this study. We analyzed KiSS1 mRNA expression by real-time reverse transcription PCR in colorectal cancer tissue and paired adjacent normal mucosa. KiSS1 protein expression in early- and advanced-stage colorectal cancer samples was determined by immunohistochemical analysis. Decreased KiSS1 expression was significantly associated with lymph node metastasis and was an independent prognostic factor. Logistic regression analysis revealed that decreased KiSS1 expression was an independent risk factor for lymph node metastasis. Immunohistochemical analysis indicated that KiSS1 was highly expressed in the cell cytoplasm of early-stage colorectal cancer cells. The loss of KiSS1 appears to correlate with the progression of lymph node metastasis. An assessment of KiSS1 expression may assist in the accurate colorectal cancer diagnosis and may contribute to predict clinical outcomes.

Antiproliferative effects of kisspeptin-10 depend on artificial GPR54 (KISS1R) expression levels

Kisspeptins are peptides derived from the metastasis suppressor gene KISS1 interacting with GPR54 as their corresponding receptor. The KISS1/GPR54 system is one regulator of cellular motility mechanisms leading to decreased migration and invasion. Its role in cell proliferation processes is not clearly understood. In this study, breast cancer cell lines, T47D, ZR75-1, MDA‑MB‑231, MDA‑MB‑435s, MDA‑MB‑453, HCC70, HCC1806, HCC1937 and MCF‑7, were investigated for their endogenous GPR54 expression by immunocytochemistry, RT‑PCR and western blot analysis. The effect of kisspeptin‑10 on proliferation was measured in MDA‑MB‑231, MDA‑MB‑435s, HCC1806 and MCF‑7 cells. Further experiments on proliferation were carried out with cells transfected with GPR54. All of the tested breast cancer cell lines expressed GPR54 in different amounts. No effects on proliferation were detected in the breast cancer cells expressing the receptor endogenously. In transfected neuronal cells overexpressing GPR54, proliferation was significantly inhibited by kisspeptin‑10. The results indicate that the antiproliferative action of kisspeptin depends on the nature of GPR54 expression. The effect was detected in an artificial system of cells transfected with GPR54 and not in cells expressing the receptor endogenously. Thus, the antiproliferative action of kisspeptin seems not to be important for pathophysiological processes.

Kisspeptin‐54 Levels are increased in Patients with Colorectal Cancer

Recent studies have demonstrated that Kisspeptin, the product of the metastasis suppressor gene KiSS-1, could have a role in tumor progression and invasion. In this pilot study, we investigated the association of plasma Kisspeptin-54 level with colorectal cancer (CRC). Plasma Kisspeptin-54 levels were quantified using enzyme-immunoassay (EIA) kits from blood samples of 81 patients with CRC at their initial staging and 59 age-matched healthy controls. Plasma Kisspeptin-54 levels were significantly higher in CRC patients (86.2 ± 20.5) than in controls (49 ± 12.7; p < 0.005). The cutoff value for Kisspeptin-54 detection was determined as 46 ng/ml, and area under curve (AUC) value was 0.766 with sensitivity 63 %, specificity 81.4 %, positive predictive value 82.2 %, negative predictive value 61.5 %, positive likelihood ratio 3.38, and negative likelihood ratio 0.46. Increased plasma Kisspeptin-54 levels were significantly correlated with nodal involvement of CRC (Spearman, rs = 0.345, p = 0.002). Kisspeptin-54 was also found to be an independent predictive marker for lymph node metastases of CRC (p = 0; Exp(B): 2.053; 95 % CI, 1.255-2.851). Our results reveal that plasma Kisspeptin-54 measurement could be a useful diagnostic and prognostic parameter for CRC. Further prospective evaluation is needed to validate these findings and to establish the clinical usefulness of Kisspeptin-54 for CRC diagnostics.

Kiss-1 gene expression after radiation and its association with proliferation and apoptosis in colorectal cancer cells

To investigate the change of expression level of metastasis suppressor gene Kiss-1 in the colorectal cancer cell line SW480 after radiation, and to determine its association with the proliferation and apoptosis of SW480 cells. SW480 cells were divided into control group (0 Gy) and study groups (2, 4, 6, 8 Gy). Cells in the study groups were irradiated by 6-MV X-ray radiation for 48 hours. Immunohistochemistry and real-time PCR methods were used to investigate the influence of radiation on Kiss-1 gene expression of SW480. Colony formation assay was used to detect the proliferation of SW480. Flow cytometry-Annexin- V/PI assay was used to observe the change of the apoptosis rate. Compared with the control group, Kiss-1 protein expression increased after radiation of 6, 8 Gy (P<0.05), but no significant changes were observed after radiation of 2, 4 Gy(P>0.05). Kiss-1 gene mRNA level increased after radiation of 2, 4, 6 Gy, while no obvious change was observed for 8 Gy radiation. The apoptosis rates increased for 4, 6, 8 Gy radiation(P<0.05), however, there was no significant difference for 2 Gy radiation (P<0.05). Radiation may increase Kiss-1 gene expression in SW480 cells, which results in decreases proliferation and increases apoptosis in residual surviving cells.

Q36R polymorphism of KiSS-1 gene in Brazilian head and neck cancer patients

The KiSS-1 metastasis-suppressor gene (KiSS-1) product (metastin, kisspeptin) is reported to act after binding with the natural ligand of a G-protein coupled receptor and this gene product inhibits chemotaxis, invasion, and metastasis of cells. The aim of this study was to evaluate the Q36R polymorphism of KiSS-1 in patients with head and neck cancer and to compare the results with healthy individuals and its association with clinicopathological parameters. Gender, age, smoking and alcohol consumption were analyzed for 744 individual (252 head and neck cancer patients and in 522 control individuals). The molecular analysis of these individuals was made after extraction of genomic DNA using the SSCP-PCR technique. This study did not reveal any significant differences in genotype frequencies between healthy individuals and patients with head and neck cancer or with the clinical parameters. This study showed an increase frequency of the Q36R polymorphism in pharyngeal cancer.

Adipocytes Promote B16BL6 Melanoma Cell Invasion and the Epithelial-to-Mesenchymal Transition

Metastatic melanoma is one of the most deadly and evasive types of cancer. On average, cancer patients with metastatic melanoma survive only 6-9months after diagnosis. Epidemiological and animal studies suggest that obesity increases the metastatic ability of malignant melanoma, though the mechanism is not known. In the present studies, we assessed the ability of 3T3L1 adipocytes to modulate B16BL6 melanoma cell invasion and the Epithelial-to-Mesenchymal Transition (EMT). For this purpose, we induced the differentiation of 3T3L1 fibroblasts to adipocytes. Then, we collected the cell culture media from both fibroblasts and adipocytes and determined their effect on the invasive ability and EMT gene expression of B16BL6 melanoma cells. Results show that adipocyte media increased that ability of B16BL6 cells to invade. The higher invasive ability of B16BL6 melanoma cells was associated with increased expression of EMT genes such as Snai1, MMP9, Twist, and Vimentin. Additionally, the expression of the cell-to-cell adhesion protein E-cadherin and the metastasis suppressor gene Kiss1 were down-regulated in these B16BL6 cells. Also, adipocytes had high levels of the pro-inflammatory cytokine Interleukin 6 (IL-6). Treatment of B16BL6 cells with IL-6 elicited similar effects as the adipocyte media; IL-6 promoted the invasive ability of B16BL6 melanoma cells, increased the expression of Snai1, and decreased Kiss1 expression. IL-6 neutralization, however, did not have a visible effect on adipocyte media-induced invasion and snai1 staining. In summary, adipocytes may increase the invasive ability of B16BL6 melanoma cells by promoting EMT and decreasing the expression of genes such as E-cadherin and Kiss1.

Ob/ob serum promotes a mesenchymal cell phenotype in B16BL6 melanoma cells

In 2009, malignant melanoma was responsible for approximately 9,000 deaths in the US. These deaths are often associated with aggressive metastasis to secondary sites such as the lungs. Epidemiological and animal studies suggest that obesity is a risk factor for melanoma. Others have shown that B16BL6 melanoma cells metastasize more aggressively in obese ob/ob than in lean mice. However, the mechanism by which obesity promotes B16BL6 melanoma metastasis in ob/ob mice has not been identified. In the present study, we used serum obtained from control and ob/ob leptin-deficient obese mice to determine if obese serum increases the aggressive phenotype of melanoma cells. Results showed that ob/ob serum has higher levels of resistin, insulin, tPAI1, IL-6, TNF-α, and MCP-1 compared to control serum. We showed that ob/ob serum increases the invasive ability of B16BL6 melanomas. To further determine the mechanism by which ob/ob serum increases the invasive ability of melanomas, we determined the effect of ob/ob and control serum on genes associated with the epithelial-to-mesenchymal transition (EMT). Cancer cells with a mesenchymal phenotype have a higher metastatic ability. Snai1 and Twist are genes that are strongly associated with EMT and metastasis of melanomas. Our results showed that ob/ob serum increases the expression of Snai1 and Twist. Moreover, ob/ob serum increased matrix metalloproteast 9 (MMP9) activity and decreased the expression of E-cadherin and the metastasis suppressor gene Kiss1. In summary, results suggest that obesity may increase the metastatic ability of melanoma by promoting a mesenchymal cell phenotype.

Functional interrelationship between the WASF3 and KISS1 metastasis‐associated genes in breast cancer cells

Loss of WASF3 function in breast cancer cells results in loss of invasion phenotypes and reduced metastatic potential. By using oligonucleotide arrays, we now demonstrate that knockdown of WASF3 leads to the upregulation of the KISS1 metastasis suppressor gene with concomitant reduced invasion and loss of matrix metalloproteinases (MMP)-9 activity. Using a luciferase reporter, KISS1 transcription is significantly increased in the absence of WASF3. Knockdown of KISS1 in WASF3-silenced cells resulted in the recovery of the invasion phenotype. WASF3 knockdown also resulted in elevated IκBα levels in the cytoplasm and reduced levels of nuclear factor-kappa-B (NF-κB) p65/50 subunits in the nucleus. Tumor necrosis factor-alpha (TNF-α) has been associated with cell invasion through induction of MMP-9 production via KISS1 regulation of the NF-κB pathway. When WASF3 knockdown cells are treated with TNF-α, no effect is seen on invasion or nuclear translocation of NF-κB. Thus, coordinated expression patterns of the WASF3 metastasis promoter gene and the KISS1 metastasis suppressor gene appear to exert their influence through inhibition of NF-κB signaling, which in turn regulates MMP-9 production facilitating invasion.

Abstract 970: Obesity promotes melanoma metastasis by modulating Snai1 and KiSS1 expression

Abstract Malignant melanoma accounts for 75% of deaths associated with skin cancer. Its lethality comes from its aggressive metastasis to secondary sites such as the lungs. Epidemiological and animal studies suggest that obesity may increase the ability of melanomas to metastasize. The objective of these studies was to determine the mechanism by which obesity increases the aggressiveness of melanomas to metastasize. To this end, we used ob/ob mice as a model of obesity, as well as different cell culture conditions which mimic obesity, to investigate the molecular mechanism by which obesity affects the metastatic phenotype of B16BL6 mouse metastatic melanoma cells in vitro. In cell culture, we showed that serum from obese mice increased the ability of melanoma cells to invade. We showed that both obese mouse serum and conditioned medium collected from mature 3T3L1 adipocytes promoted a mesenchymal phenotype, as seen by an increased expression of genes associated with this phenotype, such as Snai1, and a corresponding decreased expression of the metastasis suppressor gene KiSS1. Our preliminary results suggest that obesity may increase the metastatic ability of melanomas via the pro-inflammatory cytokine Interleukin 6 (IL-6). Therefore, our hypothesis is that obesity promotes melanoma metastasis by promoting the epithelial-to-mesenchymal transition (EMT) and its associated phenotypic changes by up-regulating Snai1 and down-regulating KiSS1 through IL-6. These findings will help us understand how obesity affects melanoma metastasis and allow us to identify key cellular signaling pathways that can be used to prevent or possibly inhibit melanoma metastasis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 970. doi:10.1158/1538-7445.AM2011-970

Kisspeptin-10 elicits triphasic cytosolic calcium responses in immortalized GT1-7 GnRH neurones

Kisspeptins, which are alternatively called as metastin since they were originally identified as products of metastasis suppressor gene KiSS-1, are the natural ligands for the G protein-coupled receptor 54 (GPR54). Kisspeptins are the most potent activators of hypothalamic–pituitary–gonadal (HPG) axis reported to date. The pulsatile pattern of GnRH release, which results in the intermittent release of gonadotropic hormones from the pituitary, has a critical importance for reproductive function but the factors responsible from this release pattern are not known. Therefore, the pattern of kisspeptin-induced intracellular signaling and the role of PKC in the intracellular signaling cascade were investigated by fluorescence calcium imaging using the immortalized GnRH-secreting GT1-7 hypothalamic neurons. Kisspeptin-10 caused a triphasic change characterized by an initial small increase followed by a significant decrease and increase in intracellular free calcium concentrations ([Ca 2+] i ). The changes in [Ca 2+] i were significantly attenuated by pre-treatment with protein kinase C inhibitor. The compatibility of appeared mirrored-patterns of kisspeptin-10-induced changes in [Ca 2+] i concentrations in these neurons and GnRH secretion confirm the importance of intracellular calcium flux downstream from GPR54 through PKC signaling pathway.

Differential Protein Expression Profiling by iTRAQ-Two-dimensional LC-MS/MS of Human Bladder Cancer EJ138 Cells Transfected with the Metastasis Suppressor KiSS-1 Gene

KiSS-1 is a metastasis suppressor gene reported to be involved in the progression of several solid neoplasias. The loss of KiSS-1 gene expression has been shown to be inversely correlated with increasing tumor stage, distant metastases, and poor overall survival in bladder tumors. To identify the molecular pathways associated with the metastasis suppressor role of KiSS-1 in bladder cancer, we carried out a proteomics analysis of bladder cancer cells (EJ138) transiently transfected with a vector encompassing the full-length KiSS-1 gene using an iTRAQ (isobaric tags for relative and absolute quantitation) approach. Protein extracts collected after 24- and 48-h transfection were fractionated and cleaved with trypsin, and the resulting peptides were labeled with iTRAQ reagents. The labeled peptides were separated by strong cation exchange and reversed phase LC and analyzed by MALDI-TOF/TOF MS. Three software packages were utilized for data analysis: ProteinPilot for identification and quantification of differentially expressed proteins, Protein Center for gene ontology analysis, and Ingenuity Pathways Analysis to provide insight into biological networks. Comparative analysis among transfected, mock, and empty vector-exposed cells identified 1529 proteins with high confidence (>99%) showing high correlation rates among replicates (70%). The involvement of the identified proteins in biological networks served to characterize molecular pathways associated with KiSS-1 expression and to select critical candidates for verification analyses by Western blot using independent transfected replicates. As part of complementary clinical validation strategies, immunohistochemical analyses of proteins regulated by KiSS-1, such as Filamin A, were performed on bladder tumors spotted onto tissue microarrays (n = 280). In summary, our study not only served to uncover molecular mechanisms associated with the metastasis suppressor role of KiSS-1 in bladder cancer but also to reveal the biomarker role of Filamin A in bladder cancer progression and clinical outcome.

Systemic Dissemination in Cancer of Unknown Primary is Independent of Mutational Inactivation of the KiSS-1 Metastasis-suppressor Gene

Cancer of unknown primary represents a heterogeneous group of malignancies characterised by early systemic dissemination and lack of primary site. KiSS1 is a member of the metastasis-suppressor gene family whose functional role is being investigated in human malignancies. We extracted DNA from 50 paraffin-embedded unknown primary tumors and screened KiSS1 exons III and IV for presence of mutations by means of Single Strand Conformational Polymorphism and direct sequencing. Only one tumor specimen harboured a cytosine to guanine point substitution in base 242 of exon IVa, resulting in a proline to arginine switch at codon 81 of the KiSS1 protein (P81R). The remaining 49 tumors harbored wild-type KiSS1 alleles, indistinguishable from those of peripheral blood lymphocytes of 50 healthy controls. Consequently, the propensity for systemic spread of unknown primary tumors may by due to mutations in genes other than KiSS1 or aberrant epigenetic regulation.

Gene expression profiling of metastatic brain cancer

Gene expression profiling of metastatic brain tumors from primary lung adenocarcinoma, using a 17k-expression array, revealed that 1561 genes were consistently altered. Further functional classification placed the genes into seven categories: cell cycle and DNA damage repair, apoptosis, signal transduction molecules, transcription factors, invasion and metastasis, adhesion, and angiogenesis. Genes involved in apoptosis, such as caspase 2 (CASP2), transforming growth factor-beta inducible early gene (TIEG), and neuroprotective heat shock protein 70 (Hsp70) were underexpressed in metastatic brain tumors. Alterations in Rho GTPases (ARHGAP26, ARHGAP1), as well as down-regulation of the metastasis suppressor gene KiSS-1 were noted, which may contribute to tumor aggression. Overexpression of the invasion-related gene neurofibromatosis 1 (NF1), and angiogenesis-related genes vascular endothelial growth factor-B (VEGF-B) and placental growth factor (PGF) was also evidenced. Brain-specific angiogenesis inhibitors 1 and 3 (BAI1 and BAI3) were underexpressed as well. Examination of cell-adhesion and migration-related genes revealed an increased expression of integrins and extracellular matrices collagen and laminin. The study also showed alterations in p53 protein-associated genes, among these increased gene expression of p53, up-regulation of Reprimo or candidate mediator of the p53-dependent G2-arrest, down-regulation of p53-regulated apoptosis-inducing protein 1 (p53AIP1), decreased expression of tumor protein inducible nuclear protein 1 (p53DINP1), and down-regulation of Mdm4 (MDMX). The results demonstrated that genes involved in adhesion, motility, and angiogenesis were consistently up-regulated in metastatic brain tumors, while genes involved in apoptosis, neuroprotection, and suppression of angiogenesis were markedly down-regulated, collectively making these cancer cells prone to metastasis.

Transcriptional regulation of KiSS-1 gene expression in metastatic melanoma by specificity protein-1 and its coactivator DRIP-130

Loss of the metastasis suppressor gene, KiSS-1 has been strongly correlated to the progression of metastases in numerous types of cancers. The mechanism through which KiSS-1 is lost during metastasis, however, is still not completely known. Previous studies have shown that genetic material on human chromosome 6q16.3-q23 is essential for KiSS-1 expression in normal tissues. Additionally, microcell-mediated transfer of this chromosome in cancerous tissue results in rescued expression of KiSS-1 and reduced metastatic phenotype. Here, we show that loss of Sp1-coactivator protein DRIP-130, which is encoded by human chromosome 6q16.3-q23, results in reduced KiSS-1 promoter activation in highly malignant melanoma cells. Co-expression of Sp1 and DRIP-130 not only rescues KiSS-1 expression, but also induces an inhibition of the invasive and migratory behavior in highly metastatic melanoma cells, similar to the overexpression of KiSS-1 metastasis suppressor gene in those cells. Furthermore, we demonstrate that KiSS-1 expression is regulated by Sp1 elements within the first 100-bp region of the KiSS-1 promoter and that targeted deletion of a single GC-rich region spanning -93 to -58 interrupts Sp1- and DRIP-130-modulated transcriptional control of KiSS-1 expression. Our results thus suggest that DRIP-130 is a key regulator in KiSS-1 transactivation in normal tissue, and that the loss of DRIP-130 expression, as a result of the gross loss of human chromosome 6q16.3-q23, provokes increased tumor metastasis.