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.

KISS1 in metastatic cancer research and treatment: potential and paradoxes.

The significance of KISS1 goes beyond its original discovery as a metastasis suppressor. Its function as a neuropeptide involved in diverse physiologic processes is more well studied. Enthusiasm regarding KISS1 has cumulated in clinical trials in multiple fields related to reproduction and metabolism. But its cancer therapeutic space is unsettled. This review focuses on collating data from cancer and non-cancer fields in order to understand shared and disparate signaling that might inform clinical development in the cancer therapeutic and biomarker space. Research has focused on amino acid residues 68-121 (kisspeptin 54), binding to the KISS1 receptor and cellular responses. Evidence and counterevidence regarding this canonical pathway require closer look at the covariates so that the incredible potential of KISS1 can be realized.

Suppression of pancreatic cancer growth and metastasis by HMP19 identified through genome-wide shRNA screen.

Therapeutic effectiveness against metastatic or even locally advanced pancreatic ductal adenocarcinoma (PDAC) is dismal, with 5-year survival less than 5%. Even in patients who undergo potentially curative resection, most patients' tumors recur in the liver. Improving therapies targeting or preventing liver metastases is crucial for improving prognosis. To identify genes suppressing metastasis, a genome-wide shRNA screen was done using the human non-metastatic PDAC cell line, S2-028. After identification of candidates, functional validation was done using intrasplenic and orthotopic injections in athymic mice. HMP19 strongly inhibited metastasis but also partially attenuated tumor growth in the pancreas. Knockdown of HMP19 increased localization of activated ERK1/2 in the nucleus, corresponding to facilitated cell proliferation, decreased p27(Kip1) and increased cyclin E1. Over-expression of HMP19 exerted the opposite effects. Using a tissue microarray of 84 human PDAC, patients with low expression of HMP19 showed significantly higher incidence of liver metastasis (p = 0.0175) and worse prognosis (p = 0.018) after surgery. HMP19, a new metastasis/tumor suppressor in PDAC, appears to alter signaling that leads to cell proliferation and appears to offer prognostic value in human PDAC.

An Overview on the Emerging Role of the Plasma Protease Inhibitor Protein ITIH5 as a Metastasis Suppressor.

Most cancers are not detected until they have progressed to the point of becoming malignant and life-threatening. Chemotherapy and conventional medicines are often ineffective against cancer. Although we have made significant progress, new conceptual discoveries are still required to investigate new treatments. The role of metastasis suppressor genes as a therapeutic option for limiting tumor progression and metastasis has been on the anvil for some time. In this review, we discuss the role of ITIH5 as a metastasis suppressor gene and catalog its involvement in different cancers. We further shed light on the mode of action of ITIH5 based on the available data. The review will provide a new perspective on ITIH5 as an anti-metastatic protein and hopefully serve as an impetus for future studies towards the application of ITIH5 for clinical intervention in targeting metastatic cancers.

Molecular interaction of metastasis suppressor genes and tumor microenvironment in breast cancer.

Breast cancer (BC) is a leading cause of cancer-related deaths in women worldwide where the process of metastasis is a major contributor to the mortality associated with this disease. Metastasis suppressor genes are a group of genes that play a crucial role in preventing or inhibiting the spread of cancer cells. They suppress the metastasis process by inhibiting colonization and by inducing dormancy. These genes function by regulating various cellular processes in the tumor microenvironment (TME), such as cell adhesion, invasion, migration, and angiogenesis. Dysregulation of metastasis suppressor genes can lead to the acquisition of an invasive and metastatic phenotype and lead to poor prognostic outcomes. The components of the TME generally play a necessary in the metastasis progression of tumor cells. This review has identified and elaborated on the role of a few metastatic suppressors associated with the TME that have been shown to inhibit metastasis in BC by different mechanisms, such as blocking certain cell signaling molecules involved in cancer cell migration, invasion, enhancing immune surveillance of cancer cells, and promoting the formation of a protective extracellular matrix (ECM). Understanding the interaction of metastatic suppressor genes and the components of TME has important implications for the development of novel therapeutic strategies to target the metastatic cascade. Targeting these genes or their downstream signaling pathways offers a promising approach to inhibiting the spread of cancer cells and improves patient outcomes.

Methyl gallic acid entrapped ethosomal nano-vesicular system augments cytotoxicity against squamous cell carcinoma.

Methylated gallic acid (MGA) is a potent anticancer biomolecular entity (BME). Loading MGA into a nano-vesicular (NV) drug delivery system using nanotechnology approaches can increase the efficiency of the drug and its release characteristics. This study aimed to develop an ethosomal nano-vesicular (ENV) system loaded with MGA that shows augmented entrapment efficiency, release rate, and cytotoxic potential against oral cancer. The ENV system was synthesized using Soy lecithin, ethanol, and propylene glycol. The ENV system's characterization (DLS, Zeta potential, TEM, FT-IR) with and without MGA was performed. The cytotoxicity evaluation of MGA alone compared to the MGA-loaded ENV system was performed against the squamous cell carcinoma-9 (SCC-9) cell line. The DLS and zeta potential analysis revealed the size of the ENV system as 58.2 nm and-43.5 mV charge, respectively. MGA loading to ENV system increased size to 63 nm and decreased charge to -2.8 mV. Peaks of FTIR analysis confirmed the encapsulation of MGA in the ENV system. TEM studies revealed the spherical surface morphology of the MGA-loaded ENV system. Compared with conventional MGA alone administration, ENV loaded with MGA showed better drug absorption and bioavailability in vitro. Furthermore, the entrapment efficiency, in vitro drug release, and cytotoxicity results firmly establish the improved therapeutic potential of ENV loaded with MGA against oral cancer cells than MGA alone. Supplementary Information: The online version contains supplementary material available at 10.1007/s13205-023-03652-6.

Metastasis Suppressor Genes in Pancreatic Cancer: An Update.

ABSTRACT: Pancreatic cancer, especially pancreatic ductal adenocarcinoma (PDAC), has for long remained a deadly form of cancer characterized by high mortality rates resulting from metastasis to multiple organs. Several factors, including the late manifestation of the disease, partly amplified by lack of efficient screening methods, have hampered the drive to design an effective therapeutic strategy to treat this deadly cancer. Understanding the biology of PDAC progression and identifying critical genes regulating these processes are essential to overcome the barriers toward effective treatment. Metastasis suppressor genes have been shown to inhibit multiple steps in the metastatic cascade without affecting primary tumor formation and are considered to hold promise for treating metastatic cancers. In this review, we catalog the bona fide metastasis suppressor genes reported in PDAC and discuss their known mechanism of action.

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.

Label-free discrimination and quantitative analysis of oxidative stress induced cytotoxicity and potential protection of antioxidants using Raman micro-spectroscopy and machine learning.

Diesel exhaust particles (DEPs) are major constituents of air pollution and associated with numerous oxidative stress-induced human diseases. In vitro toxicity studies are useful for developing a better understanding of species-specific in vivo conditions. Conventional in vitro assessments based on oxidative biomarkers are destructive and inefficient. In this study, Raman spectroscopy, as a non-invasive imaging tool, was used to capture the molecular fingerprints of overall cellular component responses (nucleic acid, lipids, proteins, carbohydrates) to DEP damage and antioxidant protection. We apply a novel data visualization algorithm called PHATE, which preserves both global and local structure, to display the progression of cell damage over DEP exposure time. Meanwhile, a mutual information (MI) estimator was used to identify the most informative Raman peaks associated with cytotoxicity. A health index was defined to quantitatively assess the protective effects of two antioxidants (resveratrol and mesobiliverdin IXα) against DEP induced cytotoxicity. In addition, a number of machine learning classifiers were applied to successfully discriminate different treatment groups with high accuracy. Correlations between Raman spectra and immunomodulatory cytokine and chemokine levels were evaluated. In conclusion, the combination of label-free, non-disruptive Raman micro-spectroscopy and machine learning analysis is demonstrated as a useful tool in quantitative analysis of oxidative stress induced cytotoxicity and for effectively assessing various antioxidant treatments, suggesting that this framework can serve as a high throughput platform for screening various potential antioxidants based on their effectiveness at battling the effects of air pollution on human health.

Gd2O3-doped silica @ Au nanoparticles for in vitro imaging cancer biomarkers using surface-enhanced Raman scattering.

There has been an interest in developing multimodal approaches to combine the advantages of individual imaging modalities, as well as to compensate for respective weaknesses. We previously reported a composite nano-system composed of gadolinium-doped mesoporous silica nanoparticle and gold nanoparticle (Gd-Au NPs) as an efficient MRI contrast agent for in vivo cancer imaging. However, MRI lacks sensitivity and is unsuitable for in vitro cancer detection. Thus, here we performed a study to use the Gd-Au NPs for detection and imaging of a widely recognized human cancer biomarker, epidermal growth factor receptor (EGFR), in individual human cancer cells with surface-enhanced Raman scattering (SERS). The Gd-Au NPs were sequentially conjugated with a monoclonal antibody recognizing EGFR and a Raman reporter molecule, 4-meraptobenzoic acid (MBA), to generate a characteristic SERS signal at 1075cm-1. By spatially mapping the SERS intensity at 1075cm-1, cellular distribution of EGFR and its relocalization on the plasma membrane were measured in situ. In addition, the EGFR expression levels in three human cancer cell lines (S18, A431 and A549) were measured using this SERS probe, which were consistent with the comparable measurements using immunoblotting and immunofluorescence. Our SERS results show that functionalized Gd-Au NPs successfully targeted EGFR molecules in three human cancer cell lines and monitored changes in single cell EGFR distribution in situ, demonstrating its potential to study cell activity under physiological conditions. This SERS study, combined with our previous MRI study, suggests the Gd-Au nanocomposite is a promising candidate contrast agent for multimodal cancer imaging.

Cellular calcium mobilization in response to phosphoinositide delivery.

Intracellular calcium [Ca(2+)](i) is mobilized in many cell types in response to activation of phosphoinositide (PIP(n)) signaling pathways involving PtdIns(4,5)P(2) or PtdIns(3,4,5)P(3). To further explore the relationship between increases in intracellular PIP(n) concentrations and mobilization of [Ca(2+)](i), each of the seven phosphorylated phosphoinositides (PIP(n)s) were delivered into cells and the metabolism and physiological effects of the exogenously administered PIP(n)s were determined. The efficient cellular delivery of fluorophore-tagged and native PIP(n)s was accomplished using histone protein, neomycin, and dendrimeric polyamines. PtdIns(4,5)P(2) fluorophore-tagged analogs with short- and long-acyl chains were substrates for cellular enzymes in vitro and for phospholipases in stimulated fibroblasts. PtdIns(4)P, PtdIns(3,4)P(2) and PtdIns(4,5)P(2), each induced calcium mobilization rapidly after exogenous addition to fibroblasts. PtdIns(3,4,5)P(3) induced a significant, but smaller increase in intracellular calcium. These observations suggest that PIP(n)s other than PtdIns(4,5)P(2) or PtdIns(3,4,5)P(3) may have direct roles in signaling involving [Ca(2+)](i).

In vitro biophysical, microspectroscopic and cytotoxic evaluation of metastatic and non-metastatic cancer cells in responses to anti-cancer drug.

The Breast Cancer Metastasis Suppressor 1 (BRMS1) is a nucleo-cytoplasmic protein that suppresses cancer metastasis without affecting the growth of the primary tumor. Previous work has shown that it decreases the expression of protein mediators involved in chemoresistance. This study measured the biomechanical and biochemical changes in BRMS1 expression and the responses of BRMS1 to drug treatments on cancer cells in vitro. The results show that BRMS1 expression affects biomechanical properties by decreasing the Young's modulus and adhesion force of breast cancer cells after doxorubicin (DOX) exposure. Raman spectral bands corresponding to DNA/RNA, lipids and proteins were similar for all cells after DOX treatment. The expression of cytokines were similar for cancer cells after DOX exposure, although BRMS1 expression had different effects on the secretion of cytokines for breast cancer cells. The absence of significant changes on apoptosis, reactive oxygen species (ROS) expression and cell viability after BRMS1 expression shows that BRMS1 has little effect on cellular chemoresistance. Analyzing cancer protein expression is critical in evaluating therapeutics. Our study may provide evidence of the benefit of metastatic suppressor expression before chemotherapy.

Crocetinic acid inhibits hedgehog signaling to inhibit pancreatic cancer stem cells.

Pancreatic cancer is the fourth leading cause of cancer deaths in the US and no significant treatment is currently available. Here, we describe the effect of crocetinic acid, which we purified from commercial saffron compound crocetin using high performance liquid chromatography. Crocetinic acid inhibits proliferation of pancreatic cancer cell lines in a dose- and time-dependent manner. In addition, it induced apoptosis. Moreover, the compound significantly inhibited epidermal growth factor receptor and Akt phosphorylation. Furthermore, crocetinic acid decreased the number and size of the pancospheres in a dose-dependent manner, and suppressed the expression of the marker protein DCLK-1 (Doublecortin Calcium/Calmodulin-Dependent Kinase-1) suggesting that crocetinic acid targets cancer stem cells (CSC). To understand the mechanism of CSC inhibition, the signaling pathways affected by purified crocetinic acid were dissected. Sonic hedgehog (Shh) upon binding to its cognate receptor patched, allows smoothened to accumulate and activate Gli transcription factor. Crocetinic acid inhibited the expression of both Shh and smoothened. Finally, these data were confirmed in vivo where the compound at a dose of 0.5 mg/Kg bw suppressed growth of tumor xenografts. Collectively, these data suggest that purified crocetinic acid inhibits pancreatic CSC, thereby inhibiting pancreatic tumorigenesis.

Imaging of epidermal growth factor receptor on single breast cancer cells using surface-enhanced Raman spectroscopy.

Epidermal growth factor receptor (EGFR) is widely used as a biomarker for pathological grading and therapeutic targeting of human cancers. This study investigates expression, spatial distribution as well as the endocytosis of EGFR in single breast cancer cells using surface-enhanced Raman spectroscopy (SERS). By incubating anti-EGFR antibody conjugated SERS nanoprobes with an EGFR-over-expressing cancer cell line, A431, EGFR localization was measured over time and found to be located primarily at the cell surface. To further validate the constructed SERS probes, we applied this SERS probes to detect the EGFR expression on breast cancer cells (MDA-MB-435, MDA-MB-231) and their counterpart cell lines in which EGFR expression was down-regulated by breast cancer metastasis suppressor 1 (BRMS1). The results showed that SERS method not only confirms immunoblot data measuring EGFR levels, but also adds new insights regarding EGFR localization and internalization in living cells which is impossible in immunoblot method. Thus, SERS provides a powerful new tool to measure biomarkers in living cancer cells.

Metastasis suppressors in breast cancers: mechanistic insights and clinical potential.

For the most part, normal epithelial cells do not disseminate to other parts of the body and proliferate, as do metastatic cells. Presumably, a class of molecules-termed metastasis suppressors-are involved in this homeostatic control. Metastasis suppressors are, by definition, cellular factors that, when re-expressed in metastatic cells, functionally inhibit metastasis without significantly inhibiting tumor growth. In this brief review, we catalog known metastasis suppressors, what is known about their mechanism(s) of action, and experimental and clinical associations to date.

Furin is the major proprotein convertase required for KISS1-to-Kisspeptin processing.

KISS1 is a broadly functional secreted proprotein that is then processed into small peptides, termed kisspeptins (KP). Since sequence analysis showed cleavage at KR or RR dibasic sites of the nascent protein, it was hypothesized that enzyme(s) belonging to the proprotein convertase family of proteases process KISS1 to generate KP. To this end, cell lines over-expressing KISS1 were treated with the proprotein convertase inhibitors, Dec-RVKR-CMK and α1-PDX, and KISS1 processing was completely inhibited. To identify the specific enzyme(s) responsible for KISS1 processing, mRNA expression was systematically analyzed for six proprotein convertases found in secretory pathways. Consistent expression of the three proteases - furin, PCSK5 and PCSK7 - were potentially implicated in KISS1 processing. However, shRNA-mediated knockdown of furin - but not PCSK5 or PCSK7 - blocked KISS1 processing. Thus, furin appears to be the essential enzyme for the generation of kisspeptins.

BRMS1 expression alters the ultrastructural, biomechanical and biochemical properties of MDA-MB-435 human breast carcinoma cells: an AFM and Raman microspectroscopy study.

Restoring BReast cancer Metastasis Suppressor 1 (BRMS1) expression suppresses metastasis in MDA-MB-435 human breast carcinoma cells at ectopic sites without affecting tumor formation at orthotopic site in the body. BRMS1 expression induces many phenotypic alterations in 435 cells such as cell adhesion, cytoskeleton rearrangement, and the down regulation of epidermal growth factor receptor (EGFR) expression. In order to better understand the role of cellular biomechanics in breast cancer metastasis, the qualitative and quantitative detection of cellular biomechanics and biochemical composition is urgently needed. In the present work, using atomic force microscopy (AFM) and fluorescent microscopy we revealed that BRMS1 expression in 435 cells induced reorganization of F-actin and caused alteration in cytoarchitectures (cell topography and ultrastructure). Results from AFM observed increase in biomechanical properties which include cell adhesion, cellular spring constant, and Young's modulus in 435/BRMS1 cells. Raman microspectroscopy showed weaker vibrational spectroscopic bands in 435/BRMS1 cells, implying decrease in concentration of cellular biochemical components in these cells. This was despite the similar spectral patterns observed between 435 and 435/BRMS1 cells. This work demonstrated the feasibility of applying AFM and Raman techniques for in situ measurements of the cellular biomechanics and biochemical components of breast carcinoma cells. It provides vital clues in understanding of the role of cellular biomechanics in cancer metastasis, and further the development of new techniques for early diagnosis of breast cancer.

Breast cancer metastasis suppressor-1 differentially modulates growth factor signaling.

That metastatic tumor cells grow in selective non-native environments suggests an ability to differentially respond to local microenvironments. BRMS1, like other metastasis suppressors, halts ectopic growth (metastasis) without blocking orthotopic tumor formation. BRMS1-expressing tumor cells reach secondary sites but do not colonize distant tissues, compelling the hypothesis that BRMS1 selectively restricts the ability of tumor cells to respond to exogenous regulators in different tissues. Here we report that BRMS1 expression in metastatic human breast cancer cells leads to a selective reduction in epidermal growth factor receptor expression and downstream (AKT) signaling. Signaling through another receptor tyrosine kinase, hepatocyte growth factor receptor (c-Met), remains unaltered despite reduced levels of the signaling intermediate phosphatidylinositol (4,5)-bisphosphate. Interestingly, reduced downstream calcium signaling is observed following treatment with platelet-derived growth factor, consistent with decreased phosphatidylinositol (4,5)-bisphosphate. However, platelet-derived growth factor receptor expression is unaltered. Thus, BRMS1 differentially attenuates cellular responses to mitogenic signals, not only dependent upon the specific signal received, but at varying steps within the same signaling cascade. Specific modulation of signaling responses received from the microenvironment may ultimately dictate which environments are permissive/restrictive for tumor cell growth and provide insights into the biology underlying metastasis.

Synthesis and biological activity of metabolically stabilized cyclopentyl trisphosphate analogues of D-myo-Ins(1,4,5)P3.

We describe the synthesis of four novel metabolically stabilized analogues of Ins(1,4,5)P(3) based on the known cyclopentane pentaol tris(phosphate) 2: tris(phosphorothioate) 3, tris(methylenephosphate) 4, tris(sulfonamide) 5, and tris(sulfate) 6. Of these analogues, only the tris(phosphorothioate) 3 and parent tris(phosphate) 2 bound to the type I InsP(3)R construct. In addition, both the tris(phosphorothioate) 3 and parent tris(phosphate) 2 elicited calcium release in MDA MB-435 breast cancer cells. The Ins(1,4,5)P(3) agonist activities of these two compounds can be rationalized on the basis of computational docking of the ligands to the binding domain of the type I InsP(3)R.