A clinicopathological analysis of KISS1 and KISS1R expression in colorectal cancer

KISS1 metastasis suppressor in tumor dormancy: a potential therapeutic target for metastatic cancers?

Present therapeutic approaches do not effectively target metastatic cancers, often limited by their inability to eliminate already-seeded non-proliferative, growth-arrested, or therapy-resistant tumor cells. Devising effective approaches targeting dormant tumor cells has been a focus of cancer clinicians for decades. However, progress has been limited due to limited understanding of the tumor dormancy process. Studies on tumor dormancy have picked up pace and have resulted in the identification of several regulators. This review focuses on KISS1, a metastasis suppressor gene that suppresses metastasis by keeping tumor cells in a state of dormancy at ectopic sites. The review explores mechanistic insights of KISS1 and discusses its potential application as a therapeutic against metastatic cancers by eliminating quiescent cells or inducing long-term dormancy in tumor cells.

Molecular Biomarkers according to Primary Tumor Location in Colorectal Cancer: Current Standard and New Insights

According to the 2018 GLOBOCAN database, colorectal cancer is one of the most common malignancies and leading causes of cancer-related death worldwide. During the last decades, considerable progress has been made in understanding the complex pathogenetic mechanisms involved in this neoplastic disease. Due to the need to improve treatment responses and clinical outcomes of colorectal cancer patients, the identification of new molecular biomarkers became a crucial spot in clinical oncology. As biological indicators of a specific pathological or physiological process, molecular markers play a central role in cancer detection, diagnosis, outcome prediction, and treatment choice. Considering the existing evidence that malignancies originating from distinct colonic regions behave differently, it is clear that specific biomarkers can be associated to right- or left-sided colon carcinomas, reflecting the distinct molecular signatures of these different tumor entities. The aim of this review is to summarize the main differences among tumors arising from proximal and distal colon in terms of current and emerging biomarkers.

Reduced Kiss‑1 expression is associated with clinical aggressive feature of gastric cancer patients and promotes migration and invasion in gastric cancer cells

Gastric cancer (GC) causes high morbidity and mortality in patients largely due to its invasion and metastasis. Kiss‑1 has been shown to be a metastasis suppressor in various malignancies. However, its clinical significance and biological functions in GC have not been thoroughly investigated. The present study investigated the association between Kiss‑1 expression and its methylation status and clinicopathological features in GC. Kiss‑1 expression was reduced in GC and its low expression was associated with poor histological grade, lymph node metastasis and TNM III+IV stage. Kiss‑1 overexpression in AGS GC cells significantly inhibited cell proliferation, migration and invasion in vitro. Kiss‑1 knockdown promoted the proliferation, migration and invasion of HGC‑27 cells. In summary, the data demonstrated that a low expression of Kiss‑1 played a suppressive role for the proliferation, migration and invasion of GC cells. Its expression and methylation levels were associated with the clinical progression of GC. Thus, Kiss‑1 is a potential diagnostic and prognostic marker as well as a new target for the treatment of GC.

Potential roles for the kisspeptin/kisspeptin receptor system in implantation and placentation

BACKGROUND

Initially identified as suppressors of metastasis in various types of cancer, kisspeptins are a family of neuropeptides that are key regulators of the mammalian reproductive axis. Accumulating evidence has shown that kisspeptin is able to control both the pulsatile and surge GnRH release, playing fundamental roles in female reproduction, which include the secretion of gonadotropins, puberty onset, brain sex differentiation, ovulation and the metabolic regulation of fertility. Furthermore, recent studies have demonstrated the involvement of the kisspeptin system in the processes of implantation and placentation. This review summarizes the current knowledge of the pathophysiological role and utility of these local placental regulatory factors as potential biomarkers during the early human gestation.

OBJECTIVE AND RATIONALE

A successful pregnancy, from the initiation of embryo implantation to parturition, is a complex process that requires the orchestration of a series of events. This review aims to concisely summarize what is known about the role of the kisspeptin system in implantation, placentation, early human pregnancy and pregnancy-related disorders, and to develop strategies for predicting, diagnosing and treating these abnormalities.

SEARCH METHODS

Using the PubMed and Google Scholar databases, we performed comprehensive literature searches in the English language describing the advancement of kisspeptins and the kisspeptin receptor (KISS1R) in implantation, placentation and early pregnancy in humans, since its initial identification in 1996 and ending in July 2018.

OUTCOMES

Recent studies have shown the coordinated spatial and temporal expression patterns of kisspeptins and KISS1R during human pregnancy. The experimental data gathered recently suggest putative roles of kisspeptin signaling in the regulation of trophoblast invasion, embryo implantation, placentation and early pregnancy. Dysregulation of the kisspeptin system may negatively affect the processes of implantation as well as placentation. Clinical studies indicate that the circulating levels of kisspeptins or the expression levels of kisspeptin/KISS1R in the placental tissues may be used as potential diagnostic markers for women with miscarriage and gestational trophoblastic neoplasia.

WIDER IMPLICATIONS

Comprehensive research on the pathophysiological role of the kisspeptin/KISS1R system in implantation and placentation will provide a dynamic and powerful approach to understanding the processes of early pregnancy, with potential applications in observational and analytic screening as well as the diagnosis, prognosis and treatment of implantation failure and early pregnancy-related disorders.

Role of the tumor microenvironment in regulating the anti-metastatic effect of KISS1

KISS1, a metastasis suppressor gene, has been shown to block metastasis without affecting primary tumor formation. Loss of KISS1 leads to invasion and metastasis in multiple cancers, which is the leading cause of cancer morbidity and mortality. The discovery of KISS1 has provided a ray of hope for early clinical diagnosis and for designing effective treatments targeting metastatic cancer. However, this goal requires greater holistic understanding of its mechanism of action. In this review, we go back into history and highlight some key developments, from the discovery of KISS1 to its role in regulating multiple physiological processes including cancer. We discuss key emerging roles for KISS1, specifically interactions with tissue microenvironment to promote dormancy and regulation of tumor cell metabolism, acknowledged as some of the key players in tumor progression and metastasis. We finally discuss strategies whereby KISS1 might be exploited clinically to treat metastasis.

The role of kisspeptin system in cancer biology

Kisspeptins are a family of neuropeptides that are known to be critical in puberty initiation and ovulation. Apart from that kisspeptin derived peptides (KPs) are also known for their antimetastatic activities in several malignancies. Herein we report recent evidence of the role of kisspeptins in cancer biology and we examine the prospective of targeting the kisspeptin pathways leading to a better prognosis in patients with malignant diseases.

Low KISS1 expression predicts poor prognosis for patients with colorectal cancer: A meta-analysis

KISS1 and KISS1R, a novel pair of metastasis suppressors, are likely to be associated with the prognosis of colorectal cancer (CRC). Here, a meta-analysis was performed to study the role of KISS1 and KISS1R in CRC. Heterogeneity, stability and publication bias were all estimated. Six publications describing a total of 559 CRC patients were included in the present study. Low KISS1 expression predicted 70% higher risk of poor prognosis for general patients (HR, 1.71; 95% CI, 1.28-2.29) and 99% higher risk for East Asian patients (HR, 1.99; 95% CI, 1.46-2.72). Limited evidence indicated that decreased KISS1R expression might predict poor outcome (HR, 2.96; 95% CI, 1.51-5.82). Neither heterogeneity nor publication bias was identified. The current analyses suggest that low KISS1 expression predicts poor overall survival among East Asian patients with CRC. Evidence on other races and KISS1R are still insufficient, and additional studies are required to clarify the risk of CRC associated with KISS1R by race.

Autocrine production of reproductive axis neuropeptides affects proliferation of canine osteosarcoma in vitro

Background

Osteosarcoma strikes hundreds of people each year, of both advanced and younger ages, and is often terminal. Like many tumor types, these bone tumors will frequently undergo a neuroendocrine transition, utilizing autocrine and/or paracrine hormones as growth factors and/or promoters of angiogenesis to facilitate progression and metastasis. While many of these factors and their actions on tumor growth are characterized, some tumor-derived neuropeptides remain unexplored.

Methods

Using validated canine osteosarcoma cell lines in vitro, as well as cells derived from spontaneous tumors in dogs, we explored the autocrine production of two neuropeptides typically found in the hypothalamus, and most closely associated with reproduction: gonadotropin-releasing hormone (GnRH) and kisspeptin (Kiss-1). We evaluated gene expression and protein secretion of these hormones using quantitative RT-PCR and a sensitive radioimmunoassay, and explored changes in cell proliferation determined by MTS cell viability assays.

Results

Our current studies reveal that several canine osteosarcoma cell lines (COS, POS, HMPOS, D17, C4) synthesize and secrete GnRH and express the GnRH receptor, while COS and POS also express kiss1 and its cognate receptor. We have further found that GnRH and kisspeptin, exogenously applied to these tumor cells, exert significant effects on both gene expression and proliferation. Of particular interest, kisspeptin exposure stimulated GnRH secretion from COS, similarly to the functional relationship observed within the neuroendocrine reproductive axis. Additionally, GnRH and kisspeptin treatment both increased COS proliferation, which additionally manifested in increased expression of the bone remodeling ligand rankl within these cells. These effects were blocked by treatment with a specific GnRH receptor inhibitor. Both neuropeptides were found to increase expression of the specific serotonin (5HT) receptor htr2a, the activation of which has previously been associated with cellular proliferation, suggesting that production of these factors by osteosarcoma cells may act to sensitize tumors to circulating 5HT of local and/or enteric origin.

Conclusions

Here we report that kisspeptin and GnRH act as autocrine growth factors in canine osteosarcoma cells in vitro, modulating RANKL and serotonin receptor expression in a manner consistent with pro-proliferative effects. Pharmacological targeting of these hormones may represent new avenues of osteosarcoma treatment.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5363-4) contains supplementary material, which is available to authorized users.

Computational study of putative functional variants in human kisspeptin

Non-synonymous single nucleotide polymorphisms (nsSNPs) are a type of genetic mutations that result in amino acid substitution of the encoded proteins that may potentially affect its function and phenotype. An In Silico assay has been carried out by using bioinformatics prediction tools to identify nsSNPs which are responsible for important disorders in human kisspeptin (KISS1) gene. In this study, for the first time, KISS1 amino acid changes were discovered by tBlastn for EST database. A list of nsSNPs in human KISS1 gene from dbSNP, dbEST and UniProt databases were prepared. Computational analysis was performed using SIFT (Sorting Intolerant From Tolerant) and PolyPhen (Polymorphism Phenotyping) programs. Of the total 92 nsSNPs, 20 were found to be damaged by both servers. Six nsSNPs (P97L, G122R, W114C, R92C, R120H and N115K) are predicted with the highest damaging scores (SIFT = 0, PolyPhen = 1). These intolerant changes may suggest their functional significance in critical regions which may affect the function and stability of KISS1 protein. Identifying these nsSNPs among the thousands of them make an opportunity to screen only those predicted deleterious by programs.

Controversial Role of Kisspeptins/KiSS-1R Signaling System in Tumor Development

KiSS-1 was first described as a metastasis suppressor gene in malignant melanoma. KiSS-1 encodes a 145 amino-acid residue peptide that is further processed, producing the 54 amino acid metastin and shorter peptides collectively named kisspeptins (KPs). KPs bind and activate KiSS-1R (GPR54). Although the KPs system has been extensively studied for its role in endocrinology of reproductive axis in mammals, its role in cancer is still controversial. Experimental evidences show that KP system exerts an anti-metastatic effect by the regulation of cellular migration and invasion in several cancer types. However, the role of KPs/KiSS-1R is very complex. Genomic studies suggest that KiSS-1/KiSS-1R expression might be different in the various stages of tumor development. Furthermore, overexpression of KiSS-1R has been reported to elicit drug resistance in triple negative breast cancer. In this review, we focused on multiple functions exerted by the KPs/KiSS-1R system in regulating tumor progression.