Rate-limiting Step In Metastasis Research Articles

Abstract 3940: Validation of TFX1, a first-in-class target for cancer metastasis

Abstract Most of the drugs approved for metastatic epithelial carcinomas treat the proliferation of the tumor and not the biology of metastasis. To date, all clinical trials around metastasis that focused on proteases, kinases, or integrins have failed in clinics. As a result, metastasis biology-focused drug discovery has been deprioritized.We asked the question as to what the rate-limiting steps of metastasis were. To answer it, we created a cell-based functional assay platform, METAssay™, that dissected all metastasis biology steps into thirty cellular assays and characterization steps. The platform identified the functional differences between metastatic and proliferating cells. This platform was normalized with patient tumor cells, and a machine learning algorithm, METSCAN™, was subsequently applied to identify the weighted steps that contributed towards successful metastasis. This led to the identification of four first-in-class targets; two transcription factors, one cytokine receptor and one nuclear hormone receptor.We then validated the relevance of the first target, TFX1, by overexpressing it in both colorectal and triple-negative breast cancer cell lines. Interestingly, apart from the expected increase in migration and invasion, all cell lines showed an increase in ROS, Autophagy, PDL-1, CD-73, quiescence, exosome uptake and a decrease in apoptosis, mitosis, and exosome secretion. Conversely, the downregulation of TFX1 showed the opposite effect. TFX1 was purified, and a biochemical isothermal calorimetry (ITC) assay was standardized with a tool compound with a KD of 107 nM. The compound effectively reduced metastatic properties in the cell lines and in multiple patient samples, as analyzed by the METAssay™ platform. Colorectal cancer cell lines overexpressing TFX1 also showed increased platelet binding, which was reduced by the tool compound, but not triple-negative cancer cell lines. Also, the effect of overexpression in non-metastatic cells was more profound than in metastatic cells, suggesting a saturating effect. Further characterization of the tool compound is currently ongoing to help establish a baseline for a novel discovery programme.The ideal drug to delay metastasis should be given to primary tumor patients with no evidence of clinical metastasis, irrespective of their pathological grading. Therefore, it should have a high bar for safety. Our goal is to collaborate on a discovery journey to identify candidates and create a companion diagnostic that will identify primary tumor patients at high risk of metastasis, thereby selecting the right patient cohort for clinical trials. Citation Format: Arnab Roy Chowdhury, Manoj Pandre, Chinmaya Amarkanth, Debabani Roy Chowdhury, John Ellingboe. Validation of TFX1, a first-in-class target for cancer metastasis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3940.

YAP Enhances Tumor Cell Dissemination by Promoting Intravascular Motility and Reentry into Systemic Circulation.

The oncogene YAP has been shown previously to promote tumor growth and metastasis. However, how YAP influences the behavior of tumor cells traveling within the circulatory system has not been as well explored. Given that rate-limiting steps of metastasis are known to occur while tumor cells enter, travel through, or exit circulation, we sought to study how YAP influences tumor cell behavior within the circulatory system. Intravital imaging in live zebrafish embryos revealed that YAP influenced the distribution of tumor cells within the animal following intravenous injection. Control cells became lodged in the first capillary bed encountered in the tail, whereas cells overexpressing constitutively active YAP were able to travel through this capillary plexus, reenter systemic circulation, and seed in the brain. YAP controlled transit through these capillaries by promoting active migration within the vasculature. These results were corroborated in a mouse model following intravenous injection, where active YAP increased the number of circulating tumor cells over time. Our results suggest a possible mechanism whereby tumor cells can spread to organs beyond the first capillary bed downstream from the primary tumor. These results also show that a specific gene can affect the distribution of tumor cells within an animal, thereby influencing the global pattern of metastasis in that animal. SIGNIFICANCE: These findings demonstrate that YAP endows tumor cells with the ability to move through capillaries, allowing them to return to and persist in circulation, thereby increasing their metastatic spread.See related commentary by Davidson, p. 3797.

Lung fibroblasts promote metastatic colonization through upregulation of stearoyl-CoA desaturase 1 in tumor cells.

As a rate-limiting step in metastasis, metastatic colonization requires survival signals from supportive stroma. However, the mechanisms driving this process are incompletely understood. Here, we showed that the proliferation of B16F10 cells was promoted when cocultured with lung fibroblasts. Meanwhile, co-injection of B16F10 tumor cells with mouse lung fibroblasts significantly increased lung metastasis. Based on GEO database, we identified stearoyl-CoA desaturase 1 (SCD1) as a novel factor promoting metastatic colonization. Importantly, we found that fibroblast-secreted cathepsin B (CTSB) induced the upregulation of SCD1 in B16F10 through Annexin A2 (ANXA2) and PI3K/Akt/mTOR pathway. The elevated SCD1 induced a higher ratio of monounsaturated fatty acids to saturated fatty acids in B16F10 cells. The changes in fatty acid composition contributed to tumor cell proliferation and metastatic colonization. Furthermore, targeting SCD1 effectively inhibited lung metastasis and prolonged the overall survival of mice. Meanwhile, the expression of SCD1 was negatively correlated with disease-free survival in five types of cancer patients. Collectively, our study identifies SCD1 as a critical modulator of tumor cell proliferation that is activated by cathepsin B, secreted by lung fibroblasts at the metastatic niche. Our novel findings provide potential therapeutic targets to prevent tumor metastasis.

Abstract 55: Separation of tetraspanin CD151 from its integrin partner α3β1 reflects an alter migratory state and predicts prostate cancer progression

Abstract The dysregulation of cell migration enables tumor cells to escape their tissue of origin and disseminate. Since cancer-related deaths are primarily caused by the dissemination of tumor cells, mechanisms of migration are both a target for therapy and an indicator of disease progression. The regulation of cell adhesion is widely recognized as a rate-limiting step in metastasis but how tumor cells achieve dynamic control over their adhesion receptors is poorly understood. During an analysis of prostate cancer progression we discovered that α3β1 expression is reduced and that its tetraspanin partner, CD151, is not “integrin-free”. We were able to detect integrin-free CD151 using antibodies specific to the integrin-binding domain of CD151. Dual staining of tumor tissue and normal tissue from prostate cancer patients for total CD151 and integrin-free CD151 revealed that the appearance of integrin-free CD151 corresponds with poor-patient outcome. In fact, the detection of integrin-free CD151 is an independent predictor of prostate cancer progression. Surprisingly, the clustering of integrin-free CD151 immobilizes tumor cells in vivo and prevents metastasis suggesting that the ability of CD151 to control migration does not depend on its α3β1 integrin partner. Indeed, integrin-free CD151 is now associated with non-integrin partners through which it can regulate tumor cell motility. These observations demonstrate that the appearance of integrin-free CD151 reflects the disruption of the CD151/ α3β1/laminin axis and thereby reveals an altered migratory ability in tumor cells. This has clinical as well molecular implications. Integrin-free CD151 can be used as a molecular indicator of disease progression and assist in the distinction between indolent (benign) and advanced disease (Palmer et al. 2013). In addition, the identification of new CD151 partners can provide new therapeutic targets to inhibit the motility of tumor cells that have undergone this change in migratory status. A preliminary evaluation identified a similar appearance of integrin-free CD151 in cancers derived from other tissues, suggesting that this change in molecular status is broadly applicable to most solid tumors. Palmer, et al. (2013). Integrin-free tetraspanin CD151 can inhibit tumor cell motility upon clustering and is a clinical indicator of prostate cancer progression. Cancer Research. Citation Format: Trenis Palmer, Carlos Martinez, Catalina Vasquez, Katie Hebron, Shanna Arnold, Celestial Jones-Paris, Susanne Chan, Venu Chalasani, Jose Gomez-Lemus, Andrew Williams, Joseph Chin, Giovanna Giannico, Tatiana Ketova, John Lewis, Andries Zijlstra. Separation of tetraspanin CD151 from its integrin partner α3β1 reflects an alter migratory state and predicts prostate cancer progression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 55. doi:10.1158/1538-7445.AM2014-55

Frizzled-7 dictates three-dimensional organization of colorectal cancer cell carcinoids

Progression of colorectal cancer (CRC) involves spatial and temporal occurrences of epithelial-mesenchymal transition (EMT), whereby tumour cells acquire a more invasive and metastatic phenotype. Subsequently, the disseminated mesenchymal tumour cells must undergo a reverse transition (mesenchymal-epithelial transition, MET) at the site of metastases, as most metastases recapitulate the pathology of their corresponding primary tumours. Importantly, initiation of tumour growth at the secondary site is the rate-limiting step in metastasis. However, investigation of this dynamic reversible EMT and MET that underpins CRC morphogenesis has been hindered by a lack of suitable in vitro models. To this end, we have established a unique in vitro model of CRC morphogenesis, which we term LIM1863-Mph (morphogenetic). LIM1863-Mph cells spontaneously undergo cyclic transitions between two-dimensional monolayer (migratory, mesenchymal) and three-dimensional sphere (carcinoid, epithelial) states. Using RNAi, we demonstrate that FZD7 is necessary for MET of the monolayer cells as loss of FZD7 results in the persistence of a mesenchymal state (increased SNAI2/decreased E-cadherin). Moreover, FZD7 is also required for migration of the LIM1863-Mph monolayer cells. During development, FZD7 orchestrates either migratory or epithelialization events depending on the context. Our findings strongly implicate similar functional diversity for FZD7 during CRC morphogenesis.

Spontaneous but not experimental metastatic activities differentiate primary tumor-derived vs metastasis-derived mouse prostate cancer cell lines.

We previously developed an in vivo mouse prostate reconstitution (MPR) model of metastatic prostate cancer using p53 'knockout' mouse urogenital sinus tissue for retroviral transduction of ras and myc oncogenes (Thompson et al., Oncogene, 10, 869, 1995). We further demonstrated contrasting responses to transforming growth factor beta-1 (TGF-beta1) in three matched pairs of early passage cell lines derived from primary prostate tumors and lung metastases generated by this model system (Sehgal et al., Cancer Res, 56, 3359, 1996). In this study we tested these cell lines for growth potential in subcutaneous and orthotopic (dorso-lateral prostate) locations and metastatic activities in both spontaneous and experimental assays. Subcutaneous and orthotopic tumors produced by cell lines derived from metastatic lesions tended to grow less rapidly but demonstrated greater spontaneous metastatic potential than the cell lines derived from primary tumors. In contrast all cell lines produced lung colonies in an experimental metastasis assay (tail vein inoculation) with the primary tumor-derived cell lines yielding higher activities in two of three matched pair analyses. The ability of all cell lines to produce lung metastases in the experimental assay, while only the metastasis-derived cell lines retain the ability to initiate and complete the entire metastatic pathway in the spontaneous assay, suggests that intravasation may be the rate-limiting step in metastasis in this model system.

Independence of metastatic ability and extravasation: metastatic ras-transformed and control fibroblasts extravasate equally well.

Escape of cancer cells from the circulation (extravasation) is thought to be a major rate-limiting step in metastasis, with few cells being able to extravasate. Furthermore, highly metastatic cells are believed to extravasate more readily than poorly metastatic cells. We assessed in vivo the extravasation ability of highly metastatic ras-transformed NIH 3T3 cells (PAP2) versus control nontumorigenic nontransformed NIH 3T3 cells and primary mouse embryo fibroblasts. Fluorescently labeled cells were injected intravenously into chicken embryo chorioallantoic membrane and analyzed by intravital videomicroscopy. The chorioallantoic membrane is an appropriate model for studying extravasation, since, at the embryonic stage used, the microvasculature exhibits a continuous basement membrane and adult permeability properties. The kinetics of extravasation were assessed by determining whether individual cells (n = 1481) were intravascular, extravascular, or in the process of extravasation, at 3, 6, and 24 h after injection. Contrary to expectations, our results showed that all three cell types extravasated with the same kinetics. By 24 h after injection > 89% of observed cells had completed extravasation from the capillary plexus. After extravasation, individual fibroblasts of all cell types demonstrated preferential migration within the mesenchymal layer toward arterioles, not to venules or lymphatics. Thus in this model and for these cells, extravasation is independent of metastatic ability. This suggests that the ability to extravasate in vivo is not necessarily predictive of subsequent metastasis formation, and that postextravasation events may be key determinants in metastasis.