Project description:Anoikis resistance or evasion of cell death triggered by cell detachment is a hallmark of cancer that is concurrent with cell survival and metastasis. Phenotypes of anoikis resistant cancer cells have been extensively investigated, however, how exposure to suspension stress may lead to acquisition of a anoikis resistance phenotype has not been previously described in detail. Here we show using a spectrum of ovarian cancer cells, that cycles of suspension stress followed by attached growth, leads to adaptation and acquisition of resistance to cell death in suspension . Comparing the stepwise transcriptomic changes as cells acquire resistance, we find strong transcriptional reprogramming in the population with a majority of differentially expressed genes being downregulated during progressive acquisition of anoikis resistance. Adapted anoikis resistant cells display an enhanced dependency on oxidative phosphorylation and are capable of evasion from T cell-mediated immune surveillance. We find that such acquired anoikis resistance is not genetic. However, transcriptional reprogramming is essential to this process as acquisition of such adaptive anoikis resistance invitro and invivo are both exquisitely sensitive to specific inhibition of transcriptional reprogramming. Our data demonstrate that recovery from the verge of anoikis leads to adaptation that promotes metastasis in ovarian cancer, but can be therapeutically prevented by specific inhibitors to transcriptional reprogramming.
Project description:Lung cancer is an intrinsically highly metastatic disease and the leading cause of cancer-related deaths worldwide. Although discovery of molecular aberrations in lung adenocarcinomas has led to development of effective targeted therapies, corresponding “drivers” in lung squamous carcinomas (LUSC) have not materialized. Extensive molecular profiling has revealed LUSC tumors have non-recurrent somatic mutations and are largely driven by copy number alterations. Because microRNAs (miRs) play increasingly important roles in regulating metastasis-relevant pathways, we evaluated whether miRs can regulate LUSC progression. By integrating bioinformatics of the Cancer Genome Atlas (TCGA) with novel, highly metastatic LUSC models, we found that miR-671-5p is a key inhibitor of LUSC metastasis. Surprisingly, miR-671-5p regulates LUSC metastasis by inhibiting a circular RNA (circRNA), CDR1as. Although the putative function of CDR1as is through miR-7 sponging, we found miR-671-5p more potently silences an axis of CDR1as and its anti-sense transcript, cerebellar degeneration related antigen 1 (CDR1). To our knowledge, no function of CDR1 has ever been described. We found loss of CDR1as and CDR1 significantly inhibited LUSC metastases. Intriguingly, CDR1 was strongly associated with an epithelial-mesenchymal transition (EMT) program in LUSC tumors, and was sufficient to promote metastases, increased migration and substrate-independent survival, known as anoikis-resistance. CDR1, which directly interacts with AP1 and COPI subunits, no longer promoted migration and anoikis-resistance upon blockade of Golgi trafficking. Our findings reveal a miR/circRNA axis that regulates LUSC metastases through an enigmatic protein, CDR1.
Project description:To investigate potential molecular targets that regulate metastasis and metabolism in anoikis-resistance of prostate cancer cells, we have establised anoikis-resistant prostate PC-3 cells with ultra-low attachment 6-well plates (Corning) and employed whole genome microarray expression profiling as a discovery platform to identify differentially expressed genes between anoikis-resistant PC-3 cells and corresponding parental cells.
Project description:Melanoma tumors are highly heterogeneous, comprising of many cell populations that vary in their potential for growth and invasion. Differential transcription factor expression contributes to these phenotypic traits. BRN2, a member of the POU domain family of transcription factors is thought to play important roles in melanoma invasion and metastasis. However, how BRN2 functions during the metastatic process of melanoma remains largely unknown. We therefore investigated the effects of BRN2 expression in melanoma cells with no or low constitutive expression using a doxycycline-inducible system. Induction of BRN2 expression led to reduced proliferation and partial resistance to an inhibitor of mutated BRAF. Whole genome profiling analysis revealed novel targets and signaling pathway changes related to prevention of cell death induced by detachment from the extracellular matrix, known as anoikis resistance. Further investigation confirmed increased survival of BRN2 expressing cell lines in non-adherent conditions. Functionally, expression of BRN2 promoted induction of c-MET levels as well as increased phosphorylation of STAT3. Treatment with crizotinib, a c-MET inhibitor, decreased cellular viability of BRN2 expressing cells under non-adherent conditions to death by anoikis. These results highlight the importance of a largely overlooked transcription factor in the progression and metastasis of melanoma, and may suggest a strategy to target BRN2 expressing cells resistant to therapy and cell death by anoikis.
Project description:Anoikis (detachment-induced cell death) is a specific type of programmed cell death which occurs in response to the loss of the correct extracellular matrix connections. Anoikis resistance is an important mechanism in cancer invasiveness and metastatic behavior. Autophagy, on the other hand, involves the degradation of damaged organelles and the recycling of misfolded proteins and intracellular components. However, the intersection of these two cellular responses in lung cancer cells has not been extensively studied. Here, we identified that upon matrix deprivation, the lymphocyte lineage-specific Ets transcription factor SPIB was activated and directly enhanced SNAP47 transcription in certain lung cancer cells. Loss of attachment-induced autophagy significantly increased anoikis resistance by SPIB activation. Consistent with this function, SPIB depletion by short hairpin RNA abrogated SNAP47 transcriptional activation upon matrix deprivation. Therefore, these data delineate an important role of SPIB in autophagy-mediated anoikis resistance in lung cancer cells. Accordingly, these findings suggest that manipulating SPIB-regulated pathways in vivo and evaluating the impact of anoikis resistance warrant further investigation.
Project description:Anoikis (detachment-induced cell death) is a specific type of programmed cell death which occurs in response to the loss of the correct extracellular matrix connections. Anoikis resistance is an important mechanism in cancer invasiveness and metastatic behavior. Autophagy, on the other hand, involves the degradation of damaged organelles and the recycling of misfolded proteins and intracellular components. However, the intersection of these two cellular responses in lung cancer cells has not been extensively studied. Here, we identified that upon matrix deprivation, the lymphocyte lineage-specific Ets transcription factor SPIB was activated and directly enhanced SNAP47 transcription in certain lung cancer cells. Loss of attachment-induced autophagy significantly increased anoikis resistance by SPIB activation. Consistent with this function, SPIB depletion by short hairpin RNA abrogated SNAP47 transcriptional activation upon matrix deprivation. Therefore, these data delineate an important role of SPIB in autophagy-mediated anoikis resistance in lung cancer cells. Accordingly, these findings suggest that manipulating SPIB-regulated pathways in vivo and evaluating the impact of anoikis resistance warrant further investigation.
Project description:CCCTC-binding factor (CTCF) is an 11 zinc fingers transcription factor that functions as both an oncogenic and tumor suppressor, depending on the cancer types, through epigenetic regulation. Epigenetic regulation including DNA methylation and histone modifications are critically involved in cancer metastasis. We then hypothesized that CTCF might play a vital role in epithelial ovarian cancer metastasis. Firstly, we found that CTCF expression was elevated in ovarian cancer tissues compared to non-tumor tissues. The elevated expression of CTCF predicts poor prognosis of ovarian cancer patients. Then, we revealed that CTCF knockdown significantly inhibited the migration, invasion and metastasis of ovarian cancer cells, although it had no effect on cell proliferation and tumor growth, which have been demonstrated with both in vitro and in vivo experiments. More importantly, we observed a higher CTCF expression in metastatic lesions than that in primary lesions from ovarian cancer patients. Mechanically, PCR array demonstrated that CTCF might regulate a series of metastasis associated genes, including CTBP1, SERPINE1 and SRC. Finally, we observed positive correlations between CTCF expression and those three genes in epithelial ovarian cancer specimens. In conclusion, this study demonstrates that CTCF is an oncogene in ovarian cancer to promote tumor metastasis through broadly controlling the expression of metastasis-associated genes. Our findings suggest CTCF could be a novel drug target to treat ovarian cancer by interfering with cancer cell metastasis.
Project description:Analysis of gene expression changes in cancer cells upon interaction with platelets. The hypothesis tested in the present study was to test whether platelets can influence anoikis resistance and metastasis in ovarian cancer by influencing genes which are important for apoptosis, metastasis and proliferation. Results provide important informations of the response of HeyA8 human ovarian cancer cells upon platelet interaction and provide insights on platelet-regulated gene expression changes related to increased cancer cell survival under low attachment/anoikis conditions.
Project description:Anoikis resistance or evasion of cell death triggered by cell detachment into suspension is a hallmark of cancer that is concurrent with cell survival and metastasis. The effects of frequent matrix detachment encounters on the development of anoikis resistance in cancer remains poorly defined. Here we show using a panel of ovarian cancer models, that repeated exposure to suspension stress in vitro followed by attached recovery growth leads to the development of anoikis resistance paralleling in vivo development of anoikis resistance in ovarian cancer ascites. This resistance is concurrent with enhanced invasion, chemoresistance and the ability of anoikis adapted cells to metastasize to distant sites. Adapted anoikis resistant cells show a heightened dependency on oxidative phosphorylation and can also evade immune surveillance. We find that such acquired anoikis resistance is not genetic, as acquired resistance persists for a finite duration in the absence of suspension stress. Transcriptional reprogramming is however essential to this process, as acquisition of adaptive anoikis resistance in vitro and in vivo is exquisitely sensitive to inhibition of CDK8/19 Mediator kinase, a pleiotropic regulator of transcriptional reprogramming. Our data demonstrate that growth after recovery from repeated exposure to suspension stress is a direct contributor to metastasis and that inhibition of CDK8/19 Mediator kinase during such adaptation provides a therapeutic opportunity to prevent both local and distant metastasis in cancer.
Project description:Normal cells require adhesion to extracellular matrix for survival. Cell detachment causes a drastic increase in reactive oxygen species (ROS) that promotes anoikis. In the present study, we observed that upon detachment from matrix, human mammary epithelial cells strongly upregulate manganese superoxide dismutase (MnSOD, or SOD2), a principal mitochondrial antioxidant enzyme that detoxifies ROS through dismutation of superoxide. Induction of MnSOD by cell detachment is dependent on the NFκB transcription factor. Detachment of mammary epithelial cells potently increases mitochondrial superoxide levels, which are further elevated by depletion of MnSOD in suspended cells. Consequently, cells depleted of MnSOD are hypersensitive to matrix detachment and exhibit increased anoikis. These results suggest that detachment-induced MnSOD counters mitochondrial superoxide accumulation and confers anoikis resistance. Taken together with our previous finding that detached cells evade excessive ROS production by attenuating oxidative metabolism of glucose, we conclude that mammary epithelial cells coordinate their responses to detachment through increasing MnSOD and decreasing ROS generation from mitochondrial glucose oxidation, thereby mitigating anoikis. Anoikis is a barrier to tumor metastasis. Indeed, MnSOD expression is elevated in human breast cancer metastases compared with primary tumors. Expression of MnSOD correlates with histologic tumor grades in human cancer and contributes to cancer cell's resistance to anoikis. Our study suggests that inhibition of ROS detoxification coupled with stimulation of glucose oxidative metabolism may be an efficient strategy to enhance anoikis and block metastasis.