Metastasizing cells display a unique metabolism, which is very different from the Warburg effect that arises in primary tumors. Over short time frames, oxidative phosphorylation and ATP generation ...are prominent. Over longer time frames, mitochondrial biogenesis becomes a pronounced feature and aids metastatic success. It has not been known whether or how these two phenomena are connected. We hypothesized that Osteopontin splice variants, which synergize to increase ATP levels in deadherent cells, also increase the mitochondrial mass via the same signaling mechanisms. Here, we report that autocrine Osteopontin does indeed stimulate an increase in mitochondrial size, with the splice variant -c being more effective than the full-length form -a. Osteopontin-c achieves this via its receptor CD44v, jointly with the upregulation and co-ligation of the chloride-dependent cystine-glutamate transporter SLC7A11. The signaling proceeds through activation of the known mitochondrial biogenesis inducer PGC-1 (which acts as a transcription coactivator). Peroxide is an important intermediate in this cascade, but surprisingly acts upstream of PGC-1 and is likely produced as a consequence of SLC7A11 recruitment and activation. In vivo, suppression of the biogenesis-inducing mechanisms leads to a reduction in disseminated tumor mass. This study confirms a functional connection between the short-term oxidative metabolism and the longer-term mitochondrial biogenesis in cancer metastasis - both are induced by Osteopontin-c. The results imply possible mechanisms and targets for treating cancer metastasis.
The detachment of tumor cells from extracellular matrix and survival under anchorage-independence were recognized as the initial step of tumor metastasis. Previously we had demonstrated that ...anchorage-independence altered gene expressions and showed characteristics of cell invasiveness loss, enhanced chemosensitivity, and enhanced subcutaneous tumor formation. However, whether it affected histological phenotypes in tumor tissues remained unclear. Melanoma metastases were generated in nude mice using adherent or suspended melanoma cells. Examination of melanoma metastases revealed histological features of extensive vascular structures in adherent cell-derived tumors, while not seen in suspended cell-derived tumors. Quantitative proteomic analysis at adherent, suspended, and re-attached melanoma cells suggested that aminopeptidase N was potentially downregulated upon cell suspension or reattachment. Downregulation of aminopeptidase N by gene-specific shRNAs showed reduced cell invasiveness and enhanced subcutaneous tumor formation that was consistent with previous observations. Experiments by suppression or overexpression of aminopeptidase N expression demonstrated that aminopeptidase N regulated syndecan-1 and integrin β4 expression through PKCδ pathway. Histological analysis at melanoma metastases further suggested that CD31
/aminopeptidase N
/syndecan-1
/integrin β4
phenotypes were associated with vascular structures. In summary, we suggested the expression axis of aminopeptidase N/syndecan-1/integrin β4 in melanoma cells was suppressed by detachment stress, which diminished vascular phenotypes of melanoma metastases.
Extracellular matrix (ECM) rigidity is a major effector of cell fate decisions. Whereas cell proliferation on stiff matrices, wherein Yes-associated protein (YAP) plays a pivotal role, is well ...documented, activation of apoptosis in response to soft matrices is poorly understood. Here, we show that YAP drives the apoptotic decision as well. We find that in cells on soft matrices, YAP is recruited to small adhesions, phosphorylated at the Y357 residue, and translocated into the nucleus, ultimately leading to apoptosis. In contrast, Y357 phosphorylation levels are dramatically low in large adhesions on stiff matrices. Furthermore, mild attenuation of actomyosin contractility allows adhesion growth on soft matrices, leading to reduced Y357 phosphorylation levels and resulting in cell growth. These findings indicate that failed adhesion reinforcement drives rigidity-dependent apoptosis through YAP and that this decision is not determined solely by ECM rigidity but rather by the balance between cellular forces and ECM rigidity.
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•pYAP-Y357 accumulates at small adhesions on soft matrices and leads to apoptosis•YAP phosphorylation by c-Abl and Src drives the apoptotic decision•Failure of adhesion reinforcement determines pYAP-Y357 accumulation•Cellular decisions to undergo apoptosis or grow can be switched by myosin inhibition
Shi et al. reveal that apoptosis on soft matrices depends on YAP Tyr357 phosphorylation and its accumulation in small adhesions, followed by its nuclear translocation. This process is blocked upon adhesion reinforcement on stiff matrices or via myosin inhibition on soft ones but is induced by myosin inhibition on stiff matrices.
Growth factors in tumor environments are regulators of cell survival and metastasis. Here, we reveal the dichotomy between TGF-β superfamily growth factors BMP and TGF-β/activin and their downstream ...SMAD effectors. Gene expression profiling uncovers SOX2 as a key contextual signaling node regulated in an opposing manner by BMP2, -4, and -9 and TGF-β and activin A to impact anchorage-independent cell survival. We find that SOX2 is repressed by BMPs, leading to a reduction in intraperitoneal tumor burden and improved survival of tumor-bearing mice. Repression of SOX2 is driven by SMAD1-dependent histone H3K27me3 recruitment and DNA methylation at SOX2’s promoter. Conversely, TGF-β, which is elevated in patient ascites, and activin A can promote SOX2 expression and anchorage-independent survival by SMAD3-dependent histone H3K4me3 recruitment. Our findings identify SOX2 as a contextual and contrastingly regulated node downstream of TGF-β members controlling anchorage-independent survival and metastasis in ovarian cancers.
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•SOX2 is a key node for anchorage-independent survival in cancer•SOX2 levels are differentially balanced by TGF-β/activin and BMPs in cancer•BMP9 is a robust intraperitoneal metastasis suppressor by lowering SOX2•SOX2 regulation is contextual and at the transcriptional level
Tumor cell survival upon loss of attachment is critical for metastasis. Shonibare et al. identify SOX2 as a contextual node regulated contrastingly by BMPs and TGF-β. Regulation occurs via distinct SMAD1- and SMAD3-dependent histone recruitment and DNA methylation mechanisms influencing anchorage-independent cell survival and intraperitoneal ovarian cancer metastasis.
Anchorage Dependence and Cancer Metastasis Lee, Dong Ki; Oh, Jongwook; Park, Hyun Woo ...
Journal of Korean medical science,
05/2024, Volume:
39, Issue:
19
Journal Article
Peer reviewed
Open access
The process of cancer metastasis is dependent on the cancer cells' capacity to detach from the primary tumor, endure in a suspended state, and establish colonies in other locations. Anchorage ...dependence, which refers to the cells' reliance on attachment to the extracellular matrix (ECM), is a critical determinant of cellular shape, dynamics, behavior, and, ultimately, cell fate in nonmalignant and cancer cells. Anchorage-independent growth is a characteristic feature of cells resistant to anoikis, a programmed cell death process triggered by detachment from the ECM. This ability to grow and survive without attachment to a substrate is a crucial stage in the progression of metastasis. The recently discovered phenomenon named "adherent-to-suspension transition (AST)" alters the requirement for anchoring and enhances survival in a suspended state. AST is controlled by four transcription factors (IKAROS family zinc finger 1, nuclear factor erythroid 2, BTG anti-proliferation factor 2, and interferon regulatory factor 8) and can detach cells without undergoing the typical epithelial-mesenchymal transition. Notably, AST factors are highly expressed in circulating tumor cells compared to their attached counterparts, indicating their crucial role in the spread of cancer. Crucially, the suppression of AST substantially reduces metastasis while sparing primary tumors. These findings open up possibilities for developing targeted therapies that inhibit metastasis and emphasize the importance of AST, leading to a fundamental change in our comprehension of how cancer spreads.
A persistent infection with human papillomavirus (HPV) can induce precancerous lesions of the cervix that may ultimately develop into cancer. Cervical cancer development has been linked to altered ...microRNA (miRNA) expression, with miRNAs regulating anchorage‐independent growth being particularly important for the progression of precancerous lesions to cancer. In this study, we set out to identify and validate targets of miR‐129‐5p, a previously identified tumor suppressive miRNA involved in anchorage‐independent growth and HPV‐induced carcinogenesis. We predicted 26 potential miR‐129‐5p targets using online databases, followed by KEGG pathway enrichment analysis. RT‐qPCR and luciferase assays confirmed that 3'UTR regions of six genes (ACTN1, BMPR2, CAMK4, ELK4, EP300, and GNAQ) were targeted by miR‐129‐5p. Expressions of ACTN1, CAMK4, and ELK4 were inversely correlated to miR‐129‐5p expression in HPV‐transformed keratinocytes, and their silencing reduced anchorage‐independent growth. Concordantly, miR‐129‐5p overexpression decreased protein levels of ACTN1, BMPR2, CAMK4 and ELK4 in anchorage‐independent conditions. Additionally, c‐FOS, a downstream target of ELK4, was downregulated upon miR‐129‐5p overexpression, suggesting regulation through the ELK4/c‐FOS axis. ACTN1 and ELK4 expression was also upregulated in high‐grade precancerous lesions and cervical cancers, supporting their clinical relevance. In conclusion, we identified six targets of miR‐129‐5p involved in the regulation of anchorage‐independent growth, with ACTN1, BMPR2, ELK4, EP300, and GNAQ representing novel targets for miR‐129‐5p. For both ACTN1 and ELK4 functional and clinical relevance was confirmed, indicating that miR‐129‐5p‐regulated ACTN1 and ELK4 expression contributes to HPV‐induced carcinogenesis.
Cancer genomes accumulate numerous genetic and epigenetic modifications. Yet, human cellular transformation can be accomplished by a few genetically defined elements. These elements activate key ...pathways required to support replicative immortality and anchorage independent growth, a predictor of tumorigenesis in vivo. Here, we provide evidence that the Hippo tumor suppressor pathway is a key barrier to Ras‐mediated cellular transformation. The Hippo pathway targets YAP1 for degradation via the βTrCP‐SCF ubiquitin ligase complex. In contrast, the Ras pathway acts oppositely, to promote YAP1 stability through downregulation of the ubiquitin ligase complex substrate recognition factors SOCS5/6. Depletion of SOCS5/6 or upregulation of YAP1 can bypass the requirement for oncogenic Ras in anchorage independent growth in vitro and tumor formation in vivo. Through the YAP1 target, Amphiregulin, Ras activates the endogenous EGFR pathway, which is required for transformation. Thus, the oncogenic activity of RasV12 depends on its ability to counteract Hippo pathway activity, creating a positive feedback loop, which depends on stabilization of YAP1.
Synopsis
Ras antagonises Hippo tumor suppressor activity by direct regulation of YAP‐stability. Ras controls SOCS‐protein expression, channeling YAP into ubiquitin‐dependent degradation.
YAP expression is sufficient to bypass the role of oncogenic Ras in transformation of primary human cells, and acts via a feedback loop involving Amphiregulin and EGFR.
Ras acts via downregulation of SOCS5/6 to reduce YAP protein turnover.
By reducing YAP turnover, the Ras pathway acts in opposition to the Hippo tumor suppressor pathway, which promotes YAP turnover.
The levels of SOCS6 mRNA and the YAP target AREG were inversely correlated in colorectal cancer with a wild‐type K‐Ras gene, but not in K‐Ras mutant cancers.
Ras antagonises Hippo tumor suppressor activity by direct regulation of YAP‐stability. Ras controls SOCS‐protein expression, channeling YAP into ubiquitin‐dependent degradation.
Purpose
Breast cancer is one of the most commonly diagnosed cancers in women. Five subtypes of breast cancer differ in their genetic expression profiles and carry different prognostic values, with no ...treatments available for some types, such as triple-negative, due to the absence of genetic signatures that could otherwise be targeted by molecular therapies. Although endocrine treatments are largely successful for estrogen receptor (ER)-positive cancers, a significant proportion of patients with metastatic tumors fail to respond and acquire resistance to therapy. FOXA1 overexpression mediates endocrine therapy resistance in ER-positive breast cancer, although the regulation of chemotherapy response by FOXA1 has not been addressed previously. FOXA1, together with EP300 and RUNX1, regulates the expression of E-cadherin, and is expressed in luminal, but absent in triple-negative and basal-like breast cancers. We have previously determined that EP300 regulates drug resistance and tumor initiation capabilities in breast cancer cells.
Methods
Here we describe the generation of breast cancer cell models in which FOXA1 expression has been modulated either by expression of hairpins targeting
FOXA1
mRNA or overexpression plasmids.
Results
Upon FOXA1 knockdown in luminal MCF-7 and T47D cells, we found an increase in doxorubicin and paclitaxel sensitivity as well as a decrease in anchorage independence. Conversely, upregulation of FOXA1 in basal-like MDA-MB-231 cells led to an increase in drug resistance and anchorage independence.
Conclusion
Together, these data suggest that FOXA1 plays a role in making tumors more aggressive.
The Src tyrosine kinase is a strong tumor promotor. Over a century of research has elucidated fundamental mechanisms that drive its oncogenic potential. Src phosphorylates effector proteins to ...promote hallmarks of tumor progression. For example, Src associates with the Cas focal adhesion adaptor protein to promote anchorage independent cell growth. In addition, Src phosphorylates Cas to induce Pdpn expression to promote cell migration. Pdpn is a transmembrane receptor that can independently increase cell migration in the absence of oncogenic Src kinase activity. However, to our knowledge, effects of Src kinase activity on anchorage independent cell growth and migration have not been examined in the absence of Pdpn expression. Here, we analyzed the effects of an inducible Src kinase construct in knockout cells with and without exogenous Pdpn expression on cell morphology migration and anchorage independent growth. We report that Src promoted anchorage independent cell growth in the absence of Pdpn expression. In contrast, Src was not able to promote cell migration in the absence of Pdpn expression. In addition, continued Src kinase activity was required for cells to assume a transformed morphology since cells reverted to a nontransformed morphology upon cessation of Src kinase activity. We also used phosphoproteomic analysis to identify 28 proteins that are phosphorylated in Src transformed cells in a Pdpn dependent manner. Taken together, these data indicate that Src utilizes Pdpn to promote transformed cell growth and motility in complementary, but parallel, as opposed to serial, pathways.
Three-dimensional (3D) cell culture models are widely used in tumor studies to more accurately reflect cell-cell interactions and tumor growth conditions
. 3D anchorage-independent spheroids derived ...by culturing cells in ultra-low attachment (ULA) conditions is particularly relevant to ovarian cancer, as such cell clusters are often observed in malignant ascites of late-stage ovarian cancer patients. We and others have found that cells derived from anchorage-independent spheroids vary widely in gene expression profiles, proliferative state, and metabolism compared to cells maintained under attached culture conditions. This includes changes in mitochondrial function, which is most commonly assessed in cultured live cells by measuring oxygen consumption in extracellular flux assays. To measure mitochondrial function in anchorage-independent multicellular aggregates, we have adapted the Agilent Seahorse extracellular flux assay to optimize measurements of oxygen consumption and extracellular acidification of ovarian cancer cell spheroids generated by culture in ULA plates. This protocol includes: (i) Methods for culturing tumor cells as uniform anchorage-independent spheroids; (ii) Optimization for the transfer of spheroids to the Agilent Seahorse cell culture plates; (iii) Adaptations of the mitochondrial and glycolysis stress tests for spheroid extracellular flux analysis; and (iv) Suggestions for optimization of cell numbers, spheroid size, and normalization of oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) values. Using this method, we have found that ovarian cancer cells cultured as anchorage-independent spheroids display altered mitochondrial function compared to monolayer cultures attached to plastic dishes. This method allows for the assessment of mitochondrial function in a more relevant patho/physiological culture condition and can be adapted to evaluate mitochondrial function of various cell types that are able to aggregate into multicellular clusters in anchorage-independence. Graphic abstract: Workflow of the Extracellular Flux Assay to Measure Respiration of Anchorage-independent Tumor Cell Spheroids.
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