RESUMO
Calcium (Ca2+) is a highly versatile intracellular messenger that regulates several cellular processes. Although it is unclear how a single-second messenger coordinates various effects within a cell, there is growing evidence that spatial patterns of Ca2+ signals play an essential role in determining their specificity. Ca2+ signaling patterns can differ in various cell regions, and Ca2+ signals in the nuclear and cytoplasmic compartments have been observed to occur independently. The initiation and function of Ca2+ signaling within the nucleus are not yet fully understood. Receptor tyrosine kinases (RTKs) induce Ca2+ signaling resulting from phosphatidylinositol 4,5-bisphosphate (PIP2) hydrolysis and inositol 1,4,5-trisphosphate (InsP3) formation within the nucleus. This signaling mechanism may be responsible for the effects of specific growth factors on cell proliferation and gene transcription. This review highlights the recent advances in RTK trafficking to the nucleus and explains how these receptors initiate nuclear calcium signaling.
Assuntos
Sinalização do Cálcio , Núcleo Celular , Receptores Proteína Tirosina Quinases , Humanos , Núcleo Celular/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Receptores Proteína Tirosina Quinases/genética , Animais , Cálcio/metabolismo , Inositol 1,4,5-Trifosfato/metabolismo , Fosfatidilinositol 4,5-Difosfato/metabolismoRESUMO
PURPOSE: Cancer cell-derived exosomes are the mediator of the tumor microenvironment and the molecular content of exosomes presents a promising prognostic or predictive marker in tumor progression and the treatment response of cancer patients. The aim of this study was to identify the expression levels of receptor tyrosine kinases (RTKs) and AKT1 and mTOR before and after neoadjuvant chemotherapy (NACT) in the exosomes of BC patients compared with healthy females. METHODS: After isolating exosomes in the serum of 25 BC patients and characterization by flow cytometry, the mRNA levels of FGFR2, FGFR3, PDGFRB, AKT1 and mTOR in the exosomes were analyzed by RT-PCR. RESULTS: Our preliminary findings showed that FGFR2, PDGFRB, AKT1 and mTOR levels were significantly upregulated in BC patients before NACT compared with the healthy group (p < 0.05). Furthermore, the mRNA levels PDGFRB and AKT1 were significantly down-regulated after NACT compared with control. PDGFRB expression level could predict pathological non-response and significantly correlated with tumor size after NACT. CONCLUSION: Therefore, especially FGFR2, PDGFRB and AKT1 could be a therapeutic target as a prognostic marker, whereas PDGFRB may be a promising predictive indicator of therapy response in BC patients. However, the prognostic or predictive role of RTKs and PI3K/AKT/mTOR signaling in the exosomes should be further investigated in a large patient population.
Assuntos
Neoplasias da Mama , Feminino , Humanos , Neoplasias da Mama/patologia , Proteínas Proto-Oncogênicas c-akt/metabolismo , Fosfatidilinositol 3-Quinases/metabolismo , Prognóstico , Terapia Neoadjuvante , Receptor beta de Fator de Crescimento Derivado de Plaquetas/uso terapêutico , Serina-Treonina Quinases TOR/metabolismo , Receptores Proteína Tirosina Quinases , RNA Mensageiro , Tirosina/uso terapêutico , Microambiente TumoralRESUMO
Pancreatic cancer is a challenging malignancy, mainly due to aggressive regional involvement, early systemic dissemination, high recurrence rate, and subsequent low patient survival. Scientific advances have contributed in particular by identification of molecular targets as well as the definition of the mechanism of action of the drug candidate in the cellular microenvironment. Previously, we have reported the identification of the molecular mechanisms by which calix[6]arene (CLX6) reduces the viability and proliferation of pancreatic cancer cells. Now, we show the biochemical mechanisms by which CLX6 decreases the aggressiveness of Panc-1 cells, focusing specifically on receptor tyrosine kinases (RTK). The results show that clathrin-mediated endocytosis is involved in CLX6-induced AXL receptor tyrosine kinase degradation in Panc-1 cells. This response may be related to the interaction of CLX6 with the tyrosine kinase receptor binding site (such as AXL). As a result, RTK is internalized and degraded by endocytosis, a condition that negatively impacts events dependent on its signaling. Additionally, CLX6 inhibits migration and invasion of Panc-1 cells by downregulating FAK (downstream mediator of AXL) activity and reducing expression levels of MMP2 and MMP9, directly related to the metastatic profile of these cells. It is noteworthy that according to the mechanism proposed here, CLX6 appears as a candidate to be used in therapeutic protocols of patients that display high expression of AXL and consequently, poor diagnosis.
Assuntos
Antineoplásicos/farmacologia , Calixarenos/farmacologia , Invasividade Neoplásica/prevenção & controle , Neoplasias Pancreáticas/tratamento farmacológico , Fenóis/farmacologia , Proteínas Proto-Oncogênicas/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Linhagem Celular Tumoral , Movimento Celular/efeitos dos fármacos , Endocitose/efeitos dos fármacos , Humanos , Simulação de Acoplamento Molecular , Invasividade Neoplásica/patologia , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/patologia , Proteólise/efeitos dos fármacos , Proteínas Proto-Oncogênicas/antagonistas & inibidores , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Receptor Tirosina Quinase AxlRESUMO
Searching for targets that allow pharmacological inhibition of cell proliferation in over-proliferative states, such as cancer, leads us to finely understand the complex mechanisms orchestrating the perfect control of mitosis number, frequency and pace as well as the molecular arrangements that induce cells to enter functional quiescence and brings them back to cycling in specific conditions. Although the mechanisms regulating cell proliferation have been described several years ago, never before has so much light been shed over this machinery as during the last decade when therapy targets have been explored and molecules, either synthetic or in the form of antibodies with the potential of becoming cancer drugs were produced and adjusted for specific binding and function. Proteins containing tyrosine kinase domains, either membrane receptors or cytoplasmic molecules, plus the ones activated by those in downstream pathways, having tyrosine kinase domains or not, such as RAS which is a GTPase and serine/threonine kinases such as RAF, play crucial role in conducting proliferation information from cell surroundings to the nucleus where gene expression takes place. Tyrosine kinases phosphorylate tyrosine residues in an activating mode and are found in important growth factor receptors, such as for ligands from families collectively known as VEGF, PDGF and EGF, to name a few and in intracellular downstream molecules. They all play important roles in normal physiology and are commonly found mutated or overexpressed in neoplastic states. Our objective here is to present such kinases as druggable targets for cancer therapy, highlighting the ones for which the pharmacological arsenal is available, discussing specificity, resistance mechanisms and treatment alternatives in cases of resistance, plus listing potential targets that have not been successfully worked yet.
Assuntos
Neoplasias/metabolismo , Inibidores de Proteínas Quinases/farmacologia , Receptores Proteína Tirosina Quinases/antagonistas & inibidores , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Biomarcadores Tumorais , Ensaios Clínicos como Assunto , Descoberta de Drogas , Resistencia a Medicamentos Antineoplásicos , Humanos , Terapia de Alvo Molecular , Mutação , Neoplasias/tratamento farmacológico , Neoplasias/genética , Neoplasias/patologia , Ligação Proteica , Inibidores de Proteínas Quinases/uso terapêutico , Receptores Proteína Tirosina Quinases/genéticaRESUMO
BACKGROUND: It has become evident that intra-tumor heterogeneity of breast cancer impact on several biological processes such as proliferation, migration, cell death and also might contribute to chemotherapy resistance. The expression of Receptor Tyrosine Kinases (RTKs) has not been analyzed in the context of intra-tumor heterogeneity in a primary breast cancer cell culture. Several subpopulations were isolated from the MBCDF (M serial-breast cancer ductal F line) primary breast cancer cells and were successfully maintained in culture and divided in two groups according to their morphology and RTKs expression pattern, and correlated with biological processes like proliferation, migration, anchorage-independent cell growth, and resistance to cytotoxic chemotherapy drugs and tyrosine kinase inhibitors (TKIs). METHODS: Subpopulations were isolated from MBCDF primary breast cancer cell culture by limiting dilution. RTKs and hormone receptors were examined by Western blot. Proliferation was measure by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl-tetrazolium bromide (MTT assay). Cell viability was evaluated by Crystal Violet. Migration was assessed using Boyden chambers. Anchorage-independent cell growth was evaluated by colony formation in soft agar. RESULTS: Several subpopulations were isolated from the MBCDF breast cancer cells that were divided into two groups according to their morphology. Analysis of RTKs expression pattern showed that HER1, HER3, c-Met and VEGFR2 were expressed exclusively in cells from group 1, but not in cells from group 2. PDGFR was expressed only in cells from group 2, but not in cells from group 1. HER2, HER4, c-Kit, IGF1-R were expressed in all subpopulations. Biological processes correlated with the RTKs expression pattern. Group 2 subpopulations present the highest rate of cell proliferation, migration and anchorage-independent cell growth. Analysis of susceptibility to chemotherapy drugs and TKIs showed that only Paclitaxel and Imatinib behaved differently between groups. Group 1-cells were resistant to both Paclitaxel and Imatinib. CONCLUSIONS: We demonstrated that subpopulations from MBCDF primary cell culture could be divided into two groups according to their morphology and a RTKs excluding-expression pattern. The differences observed in RTKs expression correlate with the biological characteristics and chemoresistance of each group. These results suggest that intra-tumor heterogeneity contributes to generate groups of subpopulations with a more aggressive phenotype within the tumor.
Assuntos
Neoplasias da Mama/patologia , Mesilato de Imatinib/farmacologia , Paclitaxel/farmacologia , Cultura Primária de Células/métodos , Receptores Proteína Tirosina Quinases/metabolismo , Neoplasias da Mama/genética , Neoplasias da Mama/metabolismo , Movimento Celular/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Resistencia a Medicamentos Antineoplásicos , Feminino , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Heterogeneidade Genética , Humanos , Receptores Proteína Tirosina Quinases/genética , Células Tumorais CultivadasRESUMO
Calcium (Ca2+) is a versatile second messenger that regulates a wide range of cellular functions. Although it is not established how a single second messenger coordinates diverse effects within a cell, there is increasing evidence that the spatial patterns of Ca2+ signals may determine their specificity. Ca2+ signaling patterns can vary in different regions of the cell and Ca2+ signals in nuclear and cytoplasmic compartments have been reported to occur independently. No general paradigm has been established yet to explain whether, how, or when Ca2+ signals are initiated within the nucleus or their function. Here we highlight that receptor tyrosine kinases rapidly translocate to the nucleus. Ca2+ signals that are induced by growth factors result from phosphatidylinositol 4,5-bisphosphate hydrolysis and inositol 1,4,5-trisphosphate formation within the nucleus rather than within the cytoplasm. This novel signaling mechanism may be responsible for growth factor effects on cell proliferation.