Feedback within the inter-cellular communication and tumorigenesis in carcinomas

LncRNAs driving feedback loops to boost drug resistance: sinuous pathways in cancer

Feedback loops mediate signaling pathways to maintain cellular homeostasis. There are two types, positive and negative feedback loops. Both are subject to alterations, and consequently can become pathogenic in the development of diseases such as cancer. Long noncoding RNAs (lncRNAs) are regulators of signaling pathways through feedback loops hidden as the dark regulatory elements yet to be described with great impact on cancer tumorigenesis, development, and drug resistance. Several feedback loops have been studied in cancer, however, how they are regulated by lncRNAs is hardly evident, setting a trending topic in oncological research. In this review, we recapitulate and discuss the feedback loops that are regulated by lncRNAs to promote drug resistance. Furthermore, we propose additional strategies that allow us to identify, analyze and comprehend feedback loops regulated by lncRNAs to induce drug resistance or even to gain insight into novel feedback loops that are stimulated under the pressure of treatment and consequently increase its efficacy. This knowledge will be useful to optimize the therapeutic use of oncological drugs.

Tunneling Nanotubes and Tumor Microtubes in Cancer

Intercellular communication among cancer cells and their microenvironment is crucial to disease progression. The mechanisms by which communication occurs between distant cells in a tumor matrix remain poorly understood. In the last two decades, experimental evidence from different groups proved the existence of thin membranous tubes that interconnect cells, named tunneling nanotubes, tumor microtubes, cytonemes or membrane bridges. These highly dynamic membrane protrusions are conduits for direct cell-to-cell communication, particularly for intercellular signaling and transport of cellular cargo over long distances. Tunneling nanotubes and tumor microtubes may play an important role in the pathogenesis of cancer. They may contribute to the resistance of tumor cells against treatments such as surgery, radio- and chemotherapy. In this review, we present the current knowledge about the structure and function of tunneling nanotubes and tumor microtubes in cancer and discuss the therapeutic potential of membrane tubes in cancer treatment.

A positive feedback loop consisting of C12orf59/NF-κB/CDH11 promotes gastric cancer invasion and metastasis

Background

Metastasis remains the main cause of cancer-related death for gastric cancer (GC) patients, but the mechanisms are poorly understood. Using The Cancer Genome Atlas (TCGA) data base and bioinformatics analyses, we identified C12orf59 might act as a potential oncogenic protein in GC.

Methods

We investigate the expression pattern and clinical significance of C12orf59 in two independent cohorts of GC samples. In the training cohort, we used the X-tile program software to generate the optimal cutoff value for C12orf59 expression in order to classify patients accurately according to clinical outcome. In the validation cohort, this derived cutoff score was applied to exam the association of C12orf59 expression with survival outcome. A series of in vivo and in vitro assays were then performed to investigate the function of C12orf59 in GC.

Results

C12orf59 was significantly upregulated, and associated with poor survival outcome in two cohorts of GC samples. Gain- and loss of- function studies demonstrated C12orf59 promotes GC cell invasive and metastatic capacity both in vitro and in vivo, and induces epithelial–mesenchymal transition and angiogenesis. Mechanically, C12orf59 exerts oncogenic functions by up-regulating CDH11 expression via NF-κB signaling. Interesting, CDH11 could in turn promote NF-κB bind to C12orf59’s promoter and form a positive feedback loop to sustain the metastatic ability of GC cells. Additionally, downregulation of miR-654-5p is another important mechanism for C12orf59 overexpression in GC.

Conclusion

Our finding suggested the newly identified C12orf59/NF-κB/CDH11 feedback loop may represent a new strategy for GC treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1114-2) contains supplementary material, which is available to authorized users.

A role for RASSF1A in tunneling nanotube formation between cells through GEFH1/Rab11 pathway control

BACKGROUND

By allowing intercellular communication between cells, tunneling nanotubes (TNTs) could play critical role in cancer progression. If TNT formation is known to require cytoskeleton remodeling, key mechanism controlling their formation remains poorly understood.

METHODS

The cells of human bronchial (HBEC-3, A549) or mesothelial (H2452, H28) lines are transfected with different siRNAs (inactive, anti-RASSF1A, anti-GEFH1 and / or anti-Rab11). At 48 h post-transfection, i) the number and length of the nanotubes per cell are quantified, ii) the organelles, previously labeled with specific tracers, exchanged via these structures are monitored in real time between cells cultured in 2D or 3D and in normoxia, hypoxia or in serum deprivation condition.

RESULTS

We report that RASSF1A, a key-regulator of cytoskeleton encoded by a tumor-suppressor gene on 3p chromosome, is involved in TNTs formation in bronchial and pleural cells since controlling proper activity of RhoB guanine nucleotide exchange factor, GEF-H1. Indeed, the GEF-H1 inactivation induced by RASSF1A silencing, leads to Rab11 accumulation and subsequent exosome releasing, which in turn contribute to TNTs formation. Finally, we provide evidence involving TNT formation in bronchial carcinogenesis, by reporting that hypoxia or nutriment privation, two almost universal conditions in human cancers, fail to prevent TNTs induced by the oncogenic RASSF1A loss of expression.

CONCLUSIONS

This finding suggests for the first time that loss of RASSF1A expression could be a potential biomarker for TNTs formation, such TNTs facilitating intercellular communication favoring multistep progression of bronchial epithelial cells toward overt malignancy.

Chronic pancreatitis and resectable synchronous pancreatic carcinoma: A survival analysis

BACKGROUND/OBJECTIVES

Chronic pancreatitis (CP) is a risk factor for pancreatic cancer (PDAC). CP and PDAC are characterized by an abundance of desmoplastic tissue. The effect of this pancreatic desmoplastic tissue on PDAC is poorly understood. In literature, negative and positive effects on the natural course of PDAC have been discussed. The present analysis aims to assess the impact of CP on patients with resectable synchronous PDAC regarding short- and long-term survival.

METHODS

All patients who underwent pancreatic resection at our institution from January 2005 to January 2014 were retrospectively evaluated. Definition of CP was based on clinical and radiological aspects and histological confirmation as used previously. We identified patients with CP, CP and PDAC, and PDAC without CP and compared perioperative course and survival. Statistical analysis was performed by chi-square, Kruskal-Wallis/Mann-Whitney-U and Breslow survival analysis. P-values <0.05 were defined as statistically significant.

RESULTS

159 patients met our inclusion criteria for CP. 49 of them (30.8%) had synchronous PDAC. 145 patients had PDAC without a history of CP. There was a more advanced nodal involvement in PDAC patients with CP. Perioperative outcome and long-term survival of PDAC patients with and without CP did not differ significantly.

CONCLUSION

In a large clinical series CP had no impact on survival of patients with PDAC after resection with curative intent.

Lost in translation: applying 2D intercellular communication via tunneling nanotubes in cell culture to physiologically relevant 3D microenvironments

Tunneling nanotubes (TNTs) are membranous conduits for direct cell-to-cell communication. Until the past decade, little had been known about their composite structure, function, and mechanisms of action in both normal physiologic conditions as well as in disease states. Now TNTs are attracting increasing interest for their key role(s) in the pathogenesis of disease, including neurodegenerative disorders, inflammatory and infectious diseases, and cancer. The field of TNT biology is still in its infancy, but inroads have been made in determining potential mechanisms and function of these remarkable structures. For example, TNTs function as critical conduits for cellular exchange of information; thus, in cancer, they may play an important role in critical pathophysiologic features of the disease, including cellular invasion, metastasis, and emergence of chemotherapy drug resistance. Although the TNT field is still in a nascent stage, we propose that TNTs can be investigated as novel targets for drug-based treatment of cancer and other diseases.

Intercellular conduits in tumours: the new social network

The role of intercellular communication is increasingly recognized as being critical to tumoral invasion, metastasis, and development of resistance to therapy. The recent discovery of cellular protrusions - tumour microtubes - connecting cancer cells in gliomas, and tunneling nanotubes in several other forms of cancer, sheds light on a novel mechanism for molecular networking. Interrupting and disrupting vital lines of intercellular cross-talk via these membranous cellular tubes has strong potential as a novel form of cancer-directed therapy.

CD44 is a multidomain signaling platform that integrates extracellular matrix cues with growth factor and cytokine signals

The reception and integration of the plethora of signals a cell receives from its microenvironment is decisive in determining cell behavior. Perturbation of extracellular cues, or an inappropriate response to or integration of these signals lies at the root of many diseases such as cancer. The transmembrane protein CD44 contributes to the reception of a broad variety of microenvironmental components, including extracellular matrix constituents such as hyaluronic acid, as well as growth factors and cytokines. In this chapter, we review the range of extracellular cues that are recognized by CD44, and show how CD44 serves to integrate this information at several levels through the mechanisms by which it contributes to transduction of these various microenvironmental signals.

Intercellular communication in malignant pleural mesothelioma: properties of tunneling nanotubes

Malignant pleural mesothelioma is a particularly aggressive and locally invasive malignancy with a poor prognosis despite advances in understanding of cancer cell biology and development of new therapies. At the cellular level, cultured mesothelioma cells present a mesenchymal appearance and a strong capacity for local cellular invasion. One important but underexplored area of mesothelioma cell biology is intercellular communication. Our group has previously characterized in multiple histological subtypes of mesothelioma a unique cellular protrusion known as tunneling nanotubes (TnTs). TnTs are long, actin filament-based, narrow cytoplasmic extensions that are non-adherent when cultured in vitro and are capable of shuttling cellular cargo between connected cells. Our prior work confirmed the presence of nanotube structures in tumors resected from patients with human mesothelioma. In our current study, we quantified the number of TnTs/cell among various mesothelioma subtypes and normal mesothelial cells using confocal microscopic techniques. We also examined changes in TnT length over time in comparison to cell proliferation. We further examined potential approaches to the in vivo study of TnTs in animal models of cancer. We have developed novel approaches to study TnTs in aggressive solid tumor malignancies and define fundamental characteristics of TnTs in malignant mesothelioma. There is mounting evidence that TnTs play an important role in intercellular communication in mesothelioma and thus merit further investigation of their role in vivo.

Towards a molecular basis of oligometastatic disease: potential role of micro-RNAs

Oligometastasis is a cancer disease state characterized by a limited number of metastatic tumors involving single or few organs and with biological properties that make them potentially amenable to locoregional antitumor therapy. Current clinical data show that they are potentially curable with surgical resection or/and radiotherapy. Yet, mechanisms of progression from primary tumor to oligometastasis, rather than to polymetastases, is lacking in detail. In the current review we focus on the role of micro-RNAs in the regulation of metastases development and the role they may play in the differentiation of oligometastatic from polymetastatic progression. We also discuss the analyses of metastatic samples from oligo-and polymetastatic patients, which suggest that oligometastasis is a distinct biologic entity regulated in part by micro-RNAs. In addition, a review of the known functions of oligometastatic-specific micro-RNAs suggest that they regulate multiple steps in the metastatic cascade, including epithelial–mesenchymal transition, tumor invasion, intravasation, distant vascular extravasation and proliferation in a distant organ. Understanding the role of micro-RNAs and their target genes in oligometastatic disease may allow for the development of targeted therapies to effectively conrol the spread of metastases.

EGFR and KRAS mutations, and ALK fusions: current developments and personalized therapies for patients with advanced non-small-cell lung cancer

Personalized therapy has significantly developed in lung cancer treatment over recent years. VEGF and EGF play a major role in non-small-cell lung cancer (NSCLC) tumor angiogenesis and aggressiveness. EGFR mutation as well as KRAS and ALK rearrangements are important biomarkers in the field owing to potential targeted therapies involved in clinical practice: erlotinib, geftinib, cetuximab and crizotinib. More recently, regulation of tumor immunity through CTLA4 and PD1/L1 has emerged as a promising field in NSCLC management. This review will focus on the current and future biomarkers in the advanced NSCLC field and also address potential related targeted therapies for these patients.

Molecular mechanism of the "feedback loop" model of carcinogenesis

It is commonly accepted that cancer is a genetic disease. The current prevailing theory of carcinogenesis is the somatic mutation theory of carcinogenesis and metastasis (SMT). This theory postulates that mutations in epithelial cells lead to uncontrolled proliferation of tumor cells in a cell-autonomous fashion. This cell-autonomy is increasingly criticized. Current data suggest that the tumor microenvironment is also strongly involved in carcinogenesis. Recently, we published a hypothesis that considers the important contribution of the tumor microenvironment in carcinogenesis and complements the classical clonal evolution model.

Essentially, this “feedback loop model” (FBM) postulates that the physiological communication between cancer cells and stromal cells in inflammatory or proliferative conditions is altered by anomalous signal processing within the parenchymal cells. The inability of parenchymal cells to correctly finalize the intercellular communication might result in a perpetuation of the activated state of cells and the tumor micromilieu. The FBM is unique among the tissue-based models because in this model tumor and stromal cells interact together in a reciprocal manner to form the cancer phenotype. Contrary to the SMT, the FBM postulates that mutated genes act in a cell-heteronomous fashion, not in a cell-autonomously fashion.

Even stressed cells are individuals: second messengers of free radicals in pathophysiology of cancer

Abstract

Pathophysiological processes associated with disturbances in cell and tissue oxidative homeostasis, are associated with self-catalyzed process of lipid peroxidation. The end products of lipid peroxidation are reactive aldehydes such as 4-hydroxy-2-nonenal (HNE), acting as “second messengers of free radicals.” Although reactive aldehydes were first recognized only as cytotoxic, new evidence has come to light, related to their cell growth regulatory functions achieved through cell signaling. The variable appearance of HNE in several organs indicates that its mode of action might be related to an individual cell stress adaptation. The underlying mechanism could be that specific mutations and epigenetic changes on one hand interfere with hormesis on the other. The precise role of oxidative stress and lipid peroxidation in these processes still needs more clarification at molecular level. Finally, an individual approach to each patient, based on the individual cell response to stress, opens a new possibility of integrative medicine in cancer treatment and strongly supports modern concepts of personalized medicine.