Reduced RKIP Expression is Associated With Breast Neoplastic Progression and is Correlated With Poor Outcomes and Aberrant Methylation in Breast Carcinoma

Clinical Significance of Frequently Down-Regulated Phosphatidylethanolamine-Binding Protein-1 in Gallbladder Cancer

BACKGROUND

Promoter hypermethylation of tumor suppressor genes has been demonstrated to be one of the major mechanisms of their epigenetic regulation in various reports. We have studied the promoter methylation status of PEBP1 and evaluated its correlation with gallbladder carcinogenesis.

AIMS

PEBP1, an endogenous inhibitor of Raf/MEK/ERK signaling pathway, is a tumor suppressor gene. We aimed to study the expression profile of PEBP1 and understand the mechanism and significance of its deregulation in gallbladder cancer.

METHODS

PEBP1 expression analysis and its promoter methylation status were investigated in 77 gallbladder carcinoma (GBC) and tissue biopsies from 28 patients of gallstone disease by RT-PCR and MS-PCR, respectively.

RESULTS

Our results of the mRNA expression profiling demonstrate that PEBP1 is down-regulated in 62.3% (48/77), while 31.2% (24/77) of the gallbladder cancer biopsies show no significant change and 6.5% (5/77) show up-regulated expression compared to tissue samples of gallstone diseases. In GBC, 48.1% (N = 37) GBC biopsy samples exhibited significantly heterozygous promoter hypermethylation compared to tissue samples from gallstone diseases which show promoter hypermethylation in 3 (10.7%) samples only. In gallbladder cancer, the PEBP1 methylation is significantly associated with lymph node metastasis and shorter period of survival.

CONCLUSION

PEBP1 is frequently down-regulated and hypermethylated in gallbladder cancer and its promoter hypermethylation is a frequent and early inactivating mechanism in GBC.

Understanding Mechanisms of RKIP Regulation to Improve the Development of New Diagnostic Tools

Simple Summary

Raf Kinase Inhibitor protein is a protein that governs multiple intracellular signalling involved primarily in the progression of tumours and the development of metastases. In this review, we discussed the main mechanisms that regulate the expression and activity of RKIP with the aim of identifying the link between the transcriptional, post-transcriptional and post-translational events in different tumour settings. We also tried to analyse the studies that have measured the levels of RKIP in biological fluids in order to highlight the possible advantages and potential of RKIP assessment to obtain an accurate diagnosis and prognosis of various tumours.

Abstract

One of the most dangerous aspects of cancer cell biology is their ability to grow, spread and form metastases in the main vital organs. The identification of dysregulated markers that drive intracellular signalling involved in the malignant transformation of neoplastic cells and the understanding of the mechanisms that regulate these processes is undoubtedly a key objective for the development of new and more targeted therapies. RAF-kinase inhibitor protein (RKIP) is an endogenous tumour suppressor protein that affects tumour cell survival, proliferation, and metastasis. RKIP might serve as an early tumour biomarker since it exhibits significantly different expression levels in various cancer histologies and it is often lost during metastatic progression. In this review, we discuss the specific impact of transcriptional, post-transcriptional and post-translational regulation of expression and activation/inhibition of RKIP and focus on those tumours for which experimental data on all these factors are available. In this way, we could select how these processes cooperate with RKIP expression in (1) Lung cancer; (2) Colon cancer, (3) Breast cancer; (4) myeloid neoplasm and Multiple Myeloma, (5) Melanoma and (6) clear cell Renal Cell Carcinoma. Furthermore, since RKIP seems to be a key marker of the development of several tumours and it may be assessed easily in various biological fluids, here we discuss the potential role of RKIP dosing in more accessible biological matrices other than tissues. Moreover, this objective may intercept the still unmet need to identify new and more accurate markers for the early diagnosis and prognosis of many tumours.

A Stochastic Binary Model for the Regulation of Gene Expression to Investigate Responses to Gene Therapy

Simple Summary

Gene editing technologies reached a turning point toward epigenetic modulation for cancer treatment. Gene networks are complex systems composed of multiple non-trivially coupled elements capable of reliably processing dynamical information from the environment despite unavoidable randomness. However, this functionality is lost when the cells are in a diseased state. Hence, gene-editing-based therapeutic design can be viewed as a gene network dynamics modulation toward a healthy state. Enhancement of this control relies on mathematical models capable of effectively describing the regulation of stochastic gene expression. We use a two-state stochastic model for gene expression to investigate treatment response with a switching target gene. We show the necessity of modulating multiple gene-expression-related processes to reach a heterogeneity-reduced specific response using epigenetic-targeting cancer treatment designs. Our approach can be used as an additional tool for developing epigenetic-targeting treatments.

Abstract

In this manuscript, we use an exactly solvable stochastic binary model for the regulation of gene expression to analyze the dynamics of response to a treatment aiming to modulate the number of transcripts of a master regulatory switching gene. The challenge is to combine multiple processes with different time scales to control the treatment response by a switching gene in an unavoidable noisy environment. To establish biologically relevant timescales for the parameters of the model, we select the RKIP gene and two non-specific drugs already known for changing RKIP levels in cancer cells. We demonstrate the usefulness of our method simulating three treatment scenarios aiming to reestablish RKIP gene expression dynamics toward a pre-cancerous state: (1) to increase the promoter’s ON state duration; (2) to increase the mRNAs’ synthesis rate; and (3) to increase both rates. We show that the pre-treatment kinetic rates of ON and OFF promoter switching speeds and mRNA synthesis and degradation will affect the heterogeneity and time for treatment response. Hence, we present a strategy for reaching increased average mRNA levels with diminished heterogeneity while reducing drug dosage by simultaneously targeting multiple kinetic rates that effectively represent the chemical processes underlying the regulation of gene expression. The decrease in heterogeneity of treatment response by a target gene helps to lower the chances of emergence of resistance. Our approach may be useful for inferring kinetic constants related to the expression of antimetastatic genes or oncogenes and for the design of multi-drug therapeutic strategies targeting the processes underpinning the expression of master regulatory genes.

RKIP Pleiotropic Activities in Cancer and Inflammatory Diseases: Role in Immunity

Simple Summary

The human body consists of tissues and organs formed by cells. In each cell there is a switch that allows the cell to divide or not. In contrast, cancer cells have their switch on which allow them to divide and invade other sites leading to death. Over two decades ago, Doctor Kam Yeung, University of Toledo, Ohio, has identified a factor (RKIP) that is responsible for the on/off switch which functions normally in healthy tissues but is inactive or absent in cancers. Since this early discovery, many additional properties have been ascribed to RKIP including its role in inhibiting cancer metastasis and resistance to therapeutics and its role in modulating the normal immune response. This review describes all of the above functions of RKIP and suggesting therapeutics to induce RKIP in cancers to inhibit their growth and metastases as well as inhibit its activity to treat non-cancerous inflammatory diseases.

Abstract

Several gene products play pivotal roles in the induction of inflammation and the progression of cancer. The Raf kinase inhibitory protein (RKIP) is a cytosolic protein that exerts pleiotropic activities in such conditions, and thus regulates oncogenesis and immune-mediated diseases through its deregulation. Herein, we review the general properties of RKIP, including its: (i) molecular structure; (ii) involvement in various cell signaling pathways (i.e., inhibition of the Raf/MEK/ERK pathway; the NF-kB pathway; GRK-2 or the STAT-3 pathway; as well as regulation of the GSK3Beta signaling; and the spindle checkpoints); (iii) regulation of RKIP expression; (iv) expression’s effects on oncogenesis; (v) role in the regulation of the immune system to diseases (i.e., RKIP regulation of T cell functions; the secretion of cytokines and immune mediators, apoptosis, immune check point inhibitors and RKIP involvement in inflammatory diseases); and (vi) bioinformatic analysis between normal and malignant tissues, as well as across various immune-related cells. Overall, the regulation of RKIP in different cancers and inflammatory diseases suggest that it can be used as a potential therapeutic target in the treatment of these diseases.

RKIP Regulates Differentiation-Related Features in Melanocytic Cells

Raf Kinase Inhibitor Protein (RKIP) has been extensively reported as an inhibitor of key signaling pathways involved in the aggressive tumor phenotype and shows decreased expression in several types of cancers. However, little is known about RKIP in melanoma or regarding its function in normal cells. We examined the role of RKIP in both primary melanocytes and malignant melanoma cells and evaluated its diagnostic and prognostic value. IHC analysis revealed a significantly higher expression of RKIP in nevi compared with early-stage (stage I–II, AJCC 8th) melanoma biopsies. Proliferation, wound healing, and collagen-coated transwell assays uncovered the implication of RKIP on the motility but not on the proliferative capacity of melanoma cells as RKIP protein levels were inversely correlated with the migration capacity of both primary and metastatic melanoma cells but did not alter other parameters. As shown by RNA sequencing, endogenous RKIP knockdown in primary melanocytes triggered the deregulation of cellular differentiation-related processes, including genes (i.e., ZEB1, THY-1) closely related to the EMT. Interestingly, NANOG was identified as a putative transcriptional regulator of many of the deregulated genes, and RKIP was able to decrease the activation of the NANOG promoter. As a whole, our data support the utility of RKIP as a diagnostic marker for early-stage melanomas. In addition, these findings indicate its participation in the maintenance of a differentiated state of melanocytic cells by modulating genes intimately linked to the cellular motility and explain the progressive decrease of RKIP often described in tumors.

Current Status of Raf Kinase Inhibitor Protein (RKIP) in Lung Cancer: Behind RTK Signaling

Lung cancer is the most deadly neoplasm with the highest incidence in both genders, with non-small cell lung cancer (NSCLC) being the most frequent subtype. Somatic mutations within the tyrosine kinase domain of the epidermal growth factor receptor (EGFR) gene are key drivers of NSCLC progression, with EGFR inhibitors being particularly beneficial for patients carrying the so-called “EGFR-sensitizing mutations”. However, patients eventually acquire resistance to these EGFR inhibitors, and a better knowledge of other driven and targetable proteins will allow the design of increasingly accurate drugs against patients’ specific molecular aberrations. Raf kinase inhibitory protein (RKIP) is an important modulator of relevant intracellular signaling pathways, including those controlled by EGFR, such as MAPK. It has been reported that it has metastasis suppressor activity and a prognostic role in several solid tumors, including lung cancer. In the present review, the potential use of RKIP in the clinic as a prognostic biomarker and predictor of therapy response in lung cancer is addressed.

Targeting Raf Kinase Inhibitory Protein Regulation and Function

Raf Kinase Inhibitory Protein (RKIP) is a highly conserved kinase inhibitor that functions as a metastasis suppressor in a variety of cancers. Since RKIP can reprogram tumor cells to a non-metastatic state by rewiring kinase networks, elucidating the mechanism by which RKIP acts not only reveals molecular mechanisms that regulate metastasis, but also represents an opportunity to target these signaling networks therapeutically. Although RKIP is often lost during metastatic progression, the mechanism by which this occurs in tumor cells is complex and not well understood. In this review, we summarize our current understanding of RKIP regulation in tumors and consider experimental and computational strategies for recovering or mimicking its function by targeting mediators of metastasis.

RKIP: A Key Regulator in Tumor Metastasis Initiation and Resistance to Apoptosis: Therapeutic Targeting and Impact

RAF-kinase inhibitor protein (RKIP) is a well-established tumor suppressor that is frequently downregulated in a plethora of solid and hematological malignancies. RKIP exerts antimetastatic and pro-apoptotic properties in cancer cells, via modulation of signaling pathways and gene products involved in tumor survival and spread. Here we review the contribution of RKIP in the regulation of early metastatic steps such as epithelial–mesenchymal transition (EMT), migration, and invasion, as well as in tumor sensitivity to conventional therapeutics and immuno-mediated cytotoxicity. We further provide updated justification for targeting RKIP as a strategy to overcome tumor chemo/immuno-resistance and suppress metastasis, through the use of agents able to modulate RKIP expression in cancer cells.