Growth Arrest-Specific 6 (GAS6) Promotes Prostate Cancer Survival by G1 Arrest/S Phase Delay and Inhibition of Apoptosis During Chemotherapy in Bone Marrow

Basal-like mammary carcinomas stimulate cancer stem cell properties through AXL-signaling to induce chemotherapy resistance

Basal-like breast cancer (BLBC) is the most aggressive and heterogeneous breast cancer (BC) subtype. Conventional chemotherapies represent next to surgery the most frequently employed treatment options. Unfortunately, resistant tumor phenotypes often develop, resulting in therapeutic failure. To identify the early events occurring upon the first drug application and initiating chemotherapy resistance in BLBC, we leveraged the WAP-T syngeneic mammary carcinoma mouse model and we developed a strategy combining magnetic-activated cell sorting (MACS)-based tumor cell enrichment with high-throughput transcriptome analyses. We discovered that chemotherapy induced a massive gene expression reprogramming toward stemness acquisition to tolerate and survive the cytotoxic treatment in vitro and in vivo. Retransplantation experiments revealed that one single cycle of cytotoxic drug combination therapy (Cyclophosphamide, Adriamycin and 5-Fluorouracil) suffices to induce resistant tumor cell phenotypes in vivo. We identified Axl and its ligand Pros1 as highly induced genes driving cancer stem cell (CSC) properties upon chemotherapy in vivo and in vitro. Furthermore, from our analysis of BLBC patient datasets, we found that AXL expression is also strongly correlated with CSC-gene signatures, a poor response to conventional therapies and worse survival outcomes in those patients. Finally, we demonstrate that AXL inhibition sensitized BLBC-cells to cytotoxic treatment in vitro. Together, our data support AXL as a promising therapeutic target to optimize the efficiency of conventional cytotoxic therapies in BLBC.

NudCD1 as a prognostic marker in colorectal cancer and its role in the upregulation of cellular spindle assembly checkpoint genes and LIS1 pathways

Objective

To investigate the role of NudCD1 in spindle assembly checkpoint regulation and in the prognosis of colorectal cancer. 

Methods

Immunohistochemical staining was used to detect in situ expression of NudCD1 in 100 colorectal cancer tissue samples. A chi-square test was used to analyse the correlation between the NudCD1 protein expression level of the cancer tissues and clinicopathological features. The Kaplan–Meier survival analysis was used to assess the correlation between the NudCD1 mRNA expression and the three-year survival of patients with colorectal cancer. The impact of NudCD1 on the development of colorectal cancer and the underlying molecular mechanisms were assessed by flow cytometry cell cycle and apoptosis assays after lentiviral overexpression of NudCD1 in two colorectal cancer cell lines. Quantitative real-time PCR was used to assess mRNA expression of the cellular spindle assembly checkpoint genes BUB1, BUBR1, MAD1, CDC20 and MPS1, as well as the downstream genes LIS1, DYNC1H1, and DYNLL1 in the NudC/LIS1/dynein pathway.

Results

Compared with normal intestinal tissue (8.00% with high expression), the expression of NudCD1 protein in colorectal cancer tissue was significantly higher (58.00% with high expression, P < 0.01). In addition, expression of NudCD1 significantly correlated with the degree of tumour differentiation and the TNM staging (P < 0.01), as well as the depth of invasion of the primary tumour and lymph node metastasis (P < 0.05). However, there was no correlation with gender, age, tumour site, gross type, tumour size or distant metastasis. The Kaplan–Meier survival analysis showed that patients with high NudCD1 expression in colorectal cancer tissues had a significantly shorter survival time than those with low expression of NudCD1 (P < 0.01). Compared with the transfection of the empty vector, colon cancer HT-29 cells with overexpressed NudCD1 had significantly increased mRNA levels of BUBR1, MPS1 and LIS1. The DNA synthesis phase (S phase) was significantly shorter in cells overexpressing NudCD1 than in the control group (43.83% ± 1.57%, P < 0.05), while there was no difference in apoptosis in the two groups.

Conclusion

NudCD1 can serve as a valuable prognostic marker for colorectal cancer. It may be involved in the regulation of spindle-assembly checkpoint-gene expression and the LIS1 pathway of colorectal cancer cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-10041-4.

Osteoblastic protein kinase D1 contributes to the prostate cancer cells dormancy via GAS6-circadian clock signaling

Disseminated prostate cancer (PCa) is known to have a strong propensity for bone marrow. These disseminated tumor cells (DTCs) can survive in bone marrow for years without obvious proliferation, while maintaining the ability to develop into metastatic lesions. However, how DTCs kept dormant and recur is still uncertain. Here, we focus on the role of osteoblastic protein kinase D1 (PKD1) in PCa (PC-3 and DU145) dormancy using co-culture experiments. Using flow cytometry, western blotting, and immunofluorescence, we observed that in co-cultures osteoblasts could induce a dormant state in PCa cells, which is manifested by a fewer cell divisions, a decrease Ki-67-positive populations and a lower ERK/p38 ratio. In contrast, silencing of PKD1 gene in osteoblasts impedes co-cultured prostate cancer cell's dormancy ability. Mechanismly, protein kinase D1 (PKD1) in osteoblasts induces PCa dormancy via activating CREB1, which promoting the expression and secretion of growth arrest specific 6 (GAS6). Furthermore, GAS6-induced dormancy signaling significantly increased the expression of core circadian clock molecules in PCa cells, and a negative correlation of circadian clock proteins (BMAL1, CLOCK and DEC2) with recurrence-free survival is observed in metastatic prostate cancer patients. Interestingly, the expression of cell cycle factors (p21, p27, CDK1 and PCNA) which regulated by circadian clock also upregulated in response to GAS6 stimulation. Taken together, we provide evidence that osteoblastic PKD1/CREB1/GAS6 signaling regulates cellular dormancy of PCa cells, and highlights the importance of circadian clock in PCa cells dormancy.

Identification of Novel Diagnostic Biomarkers in Prostate Adenocarcinoma Based on the Stromal-Immune Score and Analysis of the WGCNA and ceRNA Network

Prostate cancer is still a significant global health burden in the coming decade. Novel biomarkers for detection and prognosis are needed to improve the survival of distant and advanced stage prostate cancer patients. The tumor microenvironment is an important driving factor for tumor biological functions. To investigate RNA prognostic biomarkers for prostate cancer in the tumor microenvironment, we obtained relevant data from The Cancer Genome Atlas (TCGA) database. We used the bioinformatics tools Estimation of Stromal and Immune cells in Malignant Tumor tissues using Expression data (ESTIMATE) algorithm and weighted coexpression network analysis (WGCNA) to construct tumor microenvironment stromal-immune score-based competitive endogenous RNA (ceRNA) networks. Then, the Cox regression model was performed to screen RNAs associated with prostate cancer survival. The differentially expressed gene profile in tumor stroma was significantly enriched in microenvironment functions, like immune response, cancer-related pathways, and cell adhesion-related pathways. Based on these differentially expressed genes, we constructed three ceRNA networks with 152 RNAs associated with the prostate cancer tumor microenvironment. Cox regression analysis screened 31 RNAs as the potential prognostic biomarkers for prostate cancer. The most interesting 8 prognostic biomarkers for prostate cancer included lncRNA LINC01082, miRNA hsa-miR-133a-3p, and genes TTLL12, PTGDS, GAS6, CYP27A1, PKP3, and ZG16B. In this systematic study for ceRNA networks in the tumor environment, we screened out potential biomarkers to predict prognosis for prostate cancer. Our findings might apply a valuable tool to improve prostate cancer clinical management and the new target for mechanism study and therapy.

Prostate cancer dormancy and recurrence

Prostate cancer can progress rapidly after diagnosis, but can also become undetectable after curative intent radiation or surgery, only to recur years or decades later. This capacity to lie dormant and recur long after a patient was thought to be cured, is relatively unique to prostate cancer, with estrogen receptor positive breast cancer being the other common and well-studied example. Most investigators agree that the bone marrow is an important site for dormant tumor cells, given the frequency of bone metastases and that multiple studies have reported disseminated tumor cells in patients with localized disease. However, while more difficult to study, lymph nodes and the prostate bed are likely to be important reservoirs as well. Dormant tumor cells may be truly quiescent and in the G0 phase of the cell cycle, which is commonly called cellular dormancy. However, tumor growth may also be held in check through a balance of proliferation and cell death (tumor mass dormancy). For induction of cellular dormancy, prostate cancer cells respond to signals from their microenvironment, including TGF-β2, BMP-7, GAS6, and Wnt-5a, which result in signals transduced in part through p38 MAPK and pluripotency associated transcription factors including SOX2 and NANOG, which likely affect the epi-genome through histone modification. Clinical use of adjuvant radiation or androgen deprivation has been modestly successful to prevent recurrence. With the rapid pace of discovery in this field, systemic adjuvant therapy is likely to continue to improve in the future.

Monitoring Spontaneous Quiescence and Asynchronous Proliferation-Quiescence Decisions in Prostate Cancer Cells

The proliferation-quiescence decision is a dynamic process that remains incompletely understood. Live-cell imaging with fluorescent cell cycle sensors now allows us to visualize the dynamics of cell cycle transitions and has revealed that proliferation-quiescence decisions can be highly heterogeneous, even among clonal cell lines in culture. Under normal culture conditions, cells often spontaneously enter non-cycling G0 states of varying duration and depth. This also occurs in cancer cells and G0 entry in tumors may underlie tumor dormancy and issues with cancer recurrence. Here we show that a cell cycle indicator previously shown to indicate G0 upon serum starvation, mVenus-p27K-, can also be used to monitor spontaneous quiescence in untransformed and cancer cell lines. We find that the duration of spontaneous quiescence in untransformed and cancer cells is heterogeneous and that a portion of this heterogeneity results from asynchronous proliferation-quiescence decisions in pairs of daughters after mitosis, where one daughter cell enters or remains in temporary quiescence while the other does not. We find that cancer dormancy signals influence both entry into quiescence and asynchronous proliferation-quiescence decisions after mitosis. Finally, we show that spontaneously quiescent prostate cancer cells exhibit altered expression of components of the Hippo pathway and are enriched for the stem cell markers CD133 and CD44. This suggests a hypothesis that dormancy signals could promote cancer recurrence by increasing the proportion of quiescent tumor cells poised for cell cycle re-entry with stem cell characteristics in cancer.

Identification of biomarkers, pathways and potential therapeutic target for docetaxel resistant prostate cancer

Docetaxel has been proved to provide survival benefit for advanced prostate cancer (PCa) patients. Resistance to docetaxel further reduces the survival of these patients. Herein, we performed a comprehensive bioinformatic analysis to identify differentially expressed genes (DEGs) between docetaxel sensitive and resistant PCa (DRPC) cell based on Gene Expression Omnibus (GEO) database. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were applied for functional and pathway analysis of DEGs. The STRING database, cytoscape software and plug-in 'cytoHubba' were used to construct protein-protein interaction (PPI) networks and identify hub genes. Survival analysis were performed via GEPIA database. Finally, we conducted immune infiltration analysis by TIMER. A total of 460 DEGs were identified. GO functional analysis showed that these DEGs are mainly enriched in chemotaxis, negative regulation of intracellular signal transduction, and regulation of cell adhesion, positive regulation of inflammatory response, regulation of response to cytokine stimulus. According to the results of KEGG pathway analysis, these DEGs are mainly involved in signaling by Rho GTPases, Miro GTPases and RHOBTB3; interferon Signaling; arginine biosynthesis; PI3K-Akt signaling pathway; cytokine-cytokine receptor interaction; MAPK signaling pathway. Finally, CCNB1 and EZH2 were identified as prognostic hub genes and the expression of these two genes were associated with immune infiltration. The present study may helps to improve the understanding of the molecular mechanisms of DRPC and facilitate the selection of therapeutic and prognostic biomarkers for DRPC.

Stromal-Derived Extracellular Vesicles Suppress Proliferation of Bone Metastatic Cancer Cells Mediated By ERK2

Bone is a common site of cancer metastasis, including cancers such as breast, prostate, and multiple myeloma. Disseminated tumor cells (DTC) shed from a primary tumor may travel to bone and can survive undetected for years before proliferating to form overt metastatic lesions. This period of time can be defined as metastatic latency. Once in the metastatic microenvironment, DTCs engage in intercellular communication with surrounding stromal cells, which can influence cancer cell survival, proliferation, and ultimately disease progression. The role of the surrounding tumor microenvironment in regulating DTC fate is becoming increasingly recognized. We have previously shown that in the bone microenvironment, osteoblasts are "educated" by interactions with breast cancer cells, and these "educated" osteoblasts (EO) produce soluble factors that regulate cancer cell proliferation. In this study, we provide evidence indicating that EOs produce small extracellular vesicles (sEV) that suppress breast cancer proliferation, in part through regulation of ERK1/2 signaling. In addition, using EdU-incorporation assays and propidium iodide staining we demonstrate that exposure to EO-derived sEVs decreases breast cancer cell entry to S-phase of cell cycle. We also have evidence that particular microRNAs, including miR-148a-3p, are enriched in EO-derived sEVs, and that miR-148a-3p is capable of regulating breast cancer proliferation. IMPLICATIONS: These findings underscore the importance of sEV-mediated communication in the earlier stages of cancer progression, and suggest that EO-derived sEVs may be one mechanism by which the bone microenvironment suppresses breast cancer cell proliferation.

Abscisic acid regulates dormancy of prostate cancer disseminated tumor cells in the bone marrow

Prostate cancer (PCa) commonly metastasizes to the bone where the cells frequently undergo dormancy. The escape of disseminated tumor cells from cellular dormancy is a major cause of recurrence in marrow. Abscisic acid (ABA), a phytohormone, is known to regulate dormancy of plant seeds and to regulate other stress responses in plants. Recently, ABA was found to be synthesized by mammals cells and has been linked to human disease. Yet the role of ABA in regulating tumor dormancy or reactivation is unknown. We found that ABA is produced by human marrow cells, and exogenous ABA inhibits PCa cell proliferation while increasing the expression of p27, p21, and p16 and decreasing the expression of the proliferation marker, Ki67. Further, ABA significantly increased the percentage of PCa cells in the G₀ phase of the cell cycle as well as the duration the cells were arrested in G₀. We found that ABA regulates an increase of PPARγ receptor expression and suppressed phosphorylation of mTOR/p70S6K signaling and resulting in the induction of the cellular dormancy. We then confirmed that ABA regulates G₀ cell cycle arrest through PPARγ receptor signaling in vitro and under co-culture conditions with osteoblasts. Finally, we demonstrate that ABA regulates PCa dormancy in vivo following intratibial injection in an animal model. Together these data suggest that the ABA and PPARγ signaling pathways contribute to the establishment of PCa cellular dormancy in the bone marrow microenvironment. These findings may suggest critical pathways for targeting metastatic disease.

Downregulation of miR-4755-5p promotes fluoride-induced osteoblast activation via tageting Cyclin D1

BACKGROUND

Endemic fluorosis remains a major public health issue in many countries. Fluoride can cause abnormalities in osteoblast proliferation and activation, leading to skeletal fluorosis. However, its detailed molecular mechanism remains unclear. Based on a previous study, the aim of this study is to explore the role of miRNA in osteoblast activation of skeletal fluorosis via targeting of Cyclin D1.

METHODS

A population study of coal-burning fluorosis and in vitro experiments were performed in this study. Urine fluoride (UF) concentrations of the participants were determined using a national standardized ion selective electrode approach. Based on our previous miRNA sequence results, bioinformatic analysis was used to predict miR-4755-5p targeting Cyclin D1. Quantitative real-time PCR (qRT-PCR) was used to verify the expression of miR-4755-5p. The expression of Cyclin D1 mRNA was detected by qRT-PCR. The expression of Cyclin D1 protein was detected by enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively. Cell viability was detected by CCK-8 method. The distribution of the cell cycle was analyzed by flow cytometry. The alkaline phosphatase (ALP) activity and bone Gla protein (BGP) content were detected by micronutrient enzymes standard method and ELISA. The target binding between miR-4755-5p and Cyclin D1 was verified using dual-luciferase reporter assay.

RESULTS

In the fluoride-exposed population, the results showed that with the increase in UF content, the expression of miR-4755-5p decreased gradually, while the mRNA transcription and protein expression of Cyclin D1 increased gradually. The relative miR-4755-5p expression showed a negative correlation with Cyclin D1 expression. Subsequently, in human osteoblasts treated with sodium fluoride (NaF), the results also showed that NaF caused low expression of miR-4755-5p and increased expression of Cyclin D1. Further, the results of miR-4755-5p mimic transfection confirmed that under the action of NaF, miR-4755-5p overexpression reduced Cyclin D1 protein expression within osteoblasts and further inhibited cell proliferation and activation. Simultaneously, luciferase reporter assays verified that Cyclin D1 was the miR-4755-5p direct target.

CONCLUSION

The results demonstrate that fluoride exposure induced the downregulation of miR-4755-5p and downregulated miR-4755-5p promoted fluoride-induced osteoblast activation by increasing Cyclin D1 protein expression. This study sheds new light on biomarkers and potential treatment for endemic fluorosis.

Cancer progression and the invisible phase of metastatic colonization

Metastatic dissemination occurs very early in the malignant progression of a cancer but the clinical manifestation of metastases often takes years. In recent decades, 5-year survival of patients with many solid cancers has increased due to earlier detection, local disease control and adjuvant therapies. As a consequence, we are confronted with an increase in late relapses as more antiproliferative cancer therapies prolong disease courses, raising questions about how cancer cells survive, evolve or stop growing and finally expand during periods of clinical latency. I argue here that the understanding of early metastasis formation, particularly of the currently invisible phase of metastatic colonization, will be essential for the next stage in adjuvant therapy development that reliably prevents metachronous metastasis.

Modulation of protein S and growth arrest specific 6 protein signaling inhibits pancreatic cancer cell survival and proliferation

Thrombotic complications and hypercoagulopathies are commonly associated with the progression of pancreatic ductal adenocarcinoma (PDAC). Although the mechanistic link between the two phenomena is uncertain, there is evidently an increase in procoagulant proteins and a decrease in anticoagulants in PDAC patients. For example, the anticoagulant protein S (PS) is decreased during the progression of PDAC, a condition that possibly contributes to the hypercoagulopathies. PS is also an important signaling molecule that binds a family of tyrosine kinase receptors known as TAM (Tyro3, Axl and Mer) receptors; TAM receptors are often upregulated in different cancers. Growth Arrest Specific 6 or GAS6 protein, a homolog of PS, is also a TAM receptor family ligand. The downstream signaling pathways triggered by this ligand-receptor interaction perform diverse functions, such as cell survival, proliferation, efferocytosis, and apoptosis. Targeting the TAM receptors to treat cancer has had limited success; side effects are a significant obstacle due to the widespread numerous functions of TAM receptors. In the present study, it was revealed that PS-TAM interaction was pro-apoptotic, whereas GAS6-mediated TAM signaling promoted proliferation and survival in select PDAC cell lines. Furthermore, by regulating the balance between these two signaling pathways (by overexpressing PS or knocking down GAS6), the proliferative potential of the cells was decreased. Both long-term and short-term effects of natural PS overexpression were comparable to the treatment of the cells with the drug UNC2025, which inhibits the Mer-receptor. The present study lays the foundation for investigation of PS as a therapeutic agent to control cancer progression and to concurrently arrest thrombotic events.

Novel Techniques to Study the Bone-Tumor Microenvironment

Many cancers commonly metastasize to bone. After entering the bone, cancer cells can interact with surrounding stromal cells, which ultimately influences metastasis progression. Extracellular vesicles, direct cell contact and gap junctions, and cytokines are all mechanisms of intercellular communication that have been observed to occur in the bone microenvironment. These methods of cellular crosstalk can occur between cancer cells and a variety of stromal cells, with each interaction having a different impact on cancer progression. Communication between cancer cells and bone-resident cells has previously been implicated in processes such as cancer cell trafficking and arrest in bone, cancer cell dormancy, cancer cell reactivation, and proliferation. In this chapter we review innovative techniques and model systems that can be used to study bidirectional crosstalk between cancer cells and stromal cells in the bone, with an emphasis specifically on bone-metastatic breast cancer. Investigating how metastatic cancer cells interact with, and are influenced by, the bone microenvironment is crucial to better understanding of the progression of bone metastasis.

Downregulation of microRNA-16-5p accelerates fracture healing by promoting proliferation and inhibiting apoptosis of osteoblasts in patients with traumatic brain injury

Patients who suffered a traumatic brain injury (TBI) show a faster fracture healing than patients with isolated fractures. Prior studies have suggested that this process may be accelerated through the inhibition of key microRNAs. In this study, we aimed to explore the mechanisms underlying this phenomenon, with a special focus on miR-16-5p, which is markedly decreased in patients with TBI. In vitro, miR-16-5p over-expression significantly inhibited cell proliferation in MC3T3-E1 cells transfected with agomiR-16-5p. Flow cytometry analysis further demonstrated that the overexpression of miR-16-5p induced cell cycle G1/S phase arrest and apoptosis. Moreover, target prediction and luciferase reporter assay demonstrated that miR-16-5p could negatively regulate Bcl-2 and Cyclin-D1 expression. Meanwhile, Bcl-2 and Cyclin-D1 were up-regulated after osteogenic differentiation while the down-regulation of endogenous Bcl-2 and Cyclin-D suppressed the osteogenic differentiation of MC3T3-E1 cells. In vivo, PBS, agomiR-16-5p and antagomiR-16-5p were injected into fracture sites to assess any improvements in fracture healing, which further confirmed the negative effect of miR-16-5p on fracture healing. Together, these results demonstrate miR-16-5p downregulation may accelerate fracture healing by enhancing the proliferation and inhibiting the apoptosis of osteoblasts in patients with both fractures and TBI. These phenomena may be exploited in the treatment of fractures.

Steps in Mechanotransduction Pathways that Control Cell Morphology

It is increasingly clear that mechanotransduction pathways play important roles in regulating fundamental cellular functions. Of the basic mechanical functions, the determination of cellular morphology is critical. Cells typically use many mechanosensitive steps and different cell states to achieve a polarized shape through repeated testing of the microenvironment. Indeed, morphology is determined by the microenvironment through periodic activation of motility, mechanotesting, and mechanoresponse functions by hormones, internal clocks, and receptor tyrosine kinases. Patterned substrates and controlled environments with defined rigidities limit the range of cell behavior and influence cell state decisions and are thus very useful for studying these steps. The recently defined rigidity sensing process provides a good example of how cells repeatedly test their microenvironment and is also linked to cancer. In general, aberrant extracellular matrix mechanosensing is associated with numerous conditions, including cardiovascular disease, aging, and fibrosis, that correlate with changes in tissue morphology and matrix composition. Hence, detailed descriptions of the steps involved in sensing and responding to the microenvironment are needed to better understand both the mechanisms of tissue homeostasis and the pathomechanisms of human disease.

Minimal residual disease in prostate cancer patients after primary treatment: theoretical considerations, evidence and possible use in clinical management

Minimal residual disease is that not detected by conventional imaging studies and clinically the patient remains disease free. However, with time these dormant cells will awaken and disease progression occurs, resulting in clinically and radiological detectable metastatic disease. This review addresses the concept of tumor cell dissemination from the primary tumor, the micrometastatic niche and tumor cell survival and finally the clinical utility of detecting and characterizing these tumor cells in order to guide management decisions in treating patients with prostate cancer.

NUDCD1 promotes metastasis through inducing EMT and inhibiting apoptosis in colorectal cancer

Colorectal cancer (CRC) is the third most commonly diagnosed cancer and the third leading cause of cancer death in both men and women. NudC domain containing 1 (NUDCD1) was identified as an oncoprotein which was activated or over-expressed in various human cancers. We aimed to investigate the effects and mechanisms of NUDCD1 in human CRC. The expression of NUDCD1 in CRC and pericarcinous tissues from 70 CRC patients were determined by real-time PCR, western blotting, and immunohistochemistry. The correlation between the expression of NUDCD1 and clinical characteristics was analyzed. The expression of NUDCD1 in five CRC cell lines and normal colon mucosal epithelial cell line was measured by real-time PCR. Then we knock down NUDCD1 in HCT116 and HT 29 cells. The cell viability assay, scratch assay, migration and invasion assay and flow cytometry were used to analyze NUDCD1's effects on the proliferation, migration, invasion, cell cycle and apoptosis of CRC cells. NUDCD1's effects on CRC xenografts of nude mice was also determined. Results showed that the expression of NUDCD1 was much higher in CRC tissues than that in pericarcinous tissues. Over-expression of NUDCD1 in human CRC tissues was significantly associated with lymph node metastasis, distant metastasis, and advanced stages. The expression of NUDCD1 was higher in all of the CRC cell lines than that in normal colon epithelial mucosal cells. To knockdown NUDCD1 resulted in significant decreases in cell viability and proliferation, decreased protein expression of N-cadherin and increased protein expression of E-cadherin which were biomarkers of EMT, arrested the cell cycle and increased apoptosis via down-regulated cyclin D1, Bcl2, and up-regulated cleaved-caspase3. Furthermore, to knockdown NUDCD1 inactivated IGF1R-ERK1/2 signaling pathway in vitro and in vivo, and suppressed the xenografts of CRC. In conclusion, NUDCD1 promotes the carcinogenesis and metastasis of CRC through inducing EMT and inhibiting apoptosis, which suggests NUDCD1 be a potential biomarker for CRC.

GAS6-expressing and self-sustaining cancer cells in 3D spheroids activate the PDK-RSK-mTOR pathway for survival and drug resistance

AXL receptor tyrosine kinase (RTK) inhibition presents a promising therapeutic strategy for aggressive tumor subtypes, as AXL signaling is upregulated in many cancers resistant to first-line treatments. Furthermore, the AXL ligand growth arrest-specific gene 6 (GAS6) has recently been linked to cancer drug resistance. Here, we established that challenging conditions, such as serum deprivation, divide AXL-overexpressing tumor cell lines into non-self-sustaining and self-sustaining subtypes in 3D spheroid culture. Self-sustaining cells are characterized by excessive GAS6 secretion and TAM-PDK-RSK-mTOR pathway activation. In 3D spheroid culture, the activation of the TAM-PDK-RSK-mTOR pathway proves crucial following treatment with AXL/MET inhibitor BMS777607, when the self-sustaining tumor cells react with TAM-RSK hyperactivation and enhanced SRC-AKT-mTOR signaling. Thus, bidirectional activated mTOR leads to enhanced proliferation and counteracts the drug effect. mTOR activation is accompanied by an enhanced AXL expression and hyperphosphorylation following 24 h of treatment with BMS777607. Therefore, we elucidate a double role of AXL that can be assigned to RSK-mTOR as well as SRC-AKT-mTOR pathway activation, specifically through AXL Y779 phosphorylation. This phosphosite fuels the resistance mechanism in 3D spheroids, alongside further SRC-dependent EGFR Y1173 and/or MET Y1349 phosphorylation which is defined by the cell-specific addiction. In conclusion, self-sustenance in cancer cells is based on a signaling synergy, individually balanced between GAS6 TAM-dependent PDK-RSK-mTOR survival pathway and the AXLY779/EGFR/MET-driven SRC-mTOR pathway.

Sympathetic Signaling Reactivates Quiescent Disseminated Prostate Cancer Cells in the Bone Marrow

Clinical observations have identified an association between psychologic stress and cancer relapse, suggesting that the sympathetic nervous system/norepinephrine (NE) plays a role in reactivation of dormant disseminated tumor cells (DTC) in the bone marrow niche. Here, the mechanism by which NE regulates prostate cancer DTCs in the marrow is explored. NE directly stimulated prostate cancer cell proliferation through β2-adrenergic receptors (ADRB2). NE also altered prostate cancer proliferation in the marrow niche by indirectly downregulating the secretion of the dormancy inducing molecule growth arrest specific-6 (GAS6) expressed by osteoblasts. These observations were confirmed in cocultures of prostate cancer cells expressing the fluorescent ubiquitination-based cell-cycle reporters (FUCCI) and osteoblasts isolated from GAS6-deficient (GAS6^-/-) animals. A novel ex vivo model system, using femurs harvested from GAS6^+/+ or GAS6^-/- mice, was used to confirm these results. As in coculture, when prostate cancer cells were injected into the marrow cavities of GAS6^+/+ femurs, NE altered the prostate cancer cell cycle. However, NE had less of an impact on prostate cancer cells in femur explants isolated from GAS6^-/- mice. Together, this study demonstrates that NE reactivates prostate cancer cell cycling through both a direct action on prostate cancer cells and indirectly on adjacent niche cells.Implications: Identification of mechanisms that target DTCs may provide novel therapeutic approaches to prevent or treat cancer metastases more effectively. Mol Cancer Res; 15(12); 1644-55. ©2017 AACR.

Biochemical Changes in the Niche Following Tumor Cell Invasion

Metastatic cancer is the leading cause of all cancer related deaths. Prostate cancer (PCa) metastasizes preferentially to the bone marrow, specifically within the endosteal niche. Endosteal cells secrete homing molecules that may recruit PCa cells to the bone marrow. Once there, the biochemical signature of this niche regulates PCa fate including cellular dormancy or cell cycle arrest, reactivation and resistance to chemotherapeutics. Growth factors, interleukins, adhesion molecules, as well as extra-cellular matrix proteins can collectively change the phenotype of PCa cells. Understanding the biochemical signature of endosteal niche parasitism by PCa is imperative for the establishment of new and innovative therapeutic strategies. This review seeks to summarize these important niche signatures and the potential therapeutic approaches to target metastatic PCa within the bone marrow hematopoietic stem cell (HSC) niche. J. Cell. Biochem. 118: 1956-1964, 2017. © 2016 Wiley Periodicals, Inc.

Mer Tyrosine Kinase Regulates Disseminated Prostate Cancer Cellular Dormancy

Many prostate cancer (PCa) recurrences are thought to be due to reactivation of disseminated tumor cells (DTCs). We previously found a role of the TAM family of receptor tyrosine kinases TYRO3, AXL, and MERTK in PCa dormancy regulation. However, the mechanism and contributions of the individual TAM receptors is largely unknown. Knockdown of MERTK, but not AXL or TYRO3 by shRNA in PCa cells induced a decreased ratio of P-Erk1/2 to P-p38, increased expression of p27, NR2F1, SOX2, and NANOG, induced higher levels of histone H3K9me3 and H3K27me3, and induced a G1/G0 arrest, all of which are associated with dormancy. Similar effects were also observed with siRNA. Most importantly, knockdown of MERTK in PCa cells increased metastasis free survival in an intra-cardiac injection mouse xenograft model. MERTK knockdown also failed to inhibit PCa growth in vitro and subcutaneous growth in vivo, which suggests that MERTK has specificity for dormancy regulation or requires a signal from the PCa microenvironment. The effects of MERTK on the cell cycle and histone methylation were reversed by p38 inhibitor SB203580, which indicates the importance of MAP kinases for MERTK dormancy regulation. Overall, this study shows that MERTK stimulates PCa dormancy escape through a MAP kinase dependent mechanism, also involving p27, pluripotency transcription factors, and histone methylation. J. Cell. Biochem. 118: 891-902, 2017. © 2016 Wiley Periodicals, Inc.