Extracellular matrix-specific Caveolin-1 phosphorylation on tyrosine 14 is linked to augmented melanoma metastasis but not tumorigenesis

Abstract

Caveolin-1 (CAV1) is a scaffolding protein that plays a dual role in cancer. In advanced stages of this disease, CAV1 expression in tumor cells is associated with enhanced metastatic potential, while, at earlier stages, CAV1 functions as a tumor suppressor. We recently implicated CAV1 phosphorylation on tyrosine 14 (Y14) in CAV1-enhanced cell migration. However, the contribution of this modification to the dual role of CAV1 in cancer remained unexplored. Here, we used in vitro [2D and transendothelial cell migration (TEM), invasion] and in vivo (metastasis) assays, as well as genetic and biochemical approaches to address this question in B16F10 murine melanoma cells. CAV1 promoted directional migration on fibronectin or laminin, two abundant lung extracellular matrix (ECM) components, which correlated with enhanced Y14 phosphorylation during spreading. Moreover, CAV1-driven migration, invasion, TEM and metastasis were ablated by expression of the phosphorylation null CAV1(Y14F), but not the phosphorylation mimicking CAV1(Y14E) mutation. Finally, CAV1-enhanced focal adhesion dynamics and surface expression of beta1 integrin were required for CAV1-driven TEM. Importantly, CAV1 function as a tumor suppressor in tumor formation assays was not altered by the Y14F mutation. In conclusion, our results provide critical insight to the mechanisms of CAV1 action during cancer development. Specific ECM-integrin interactions and Y14 phosphorylation are required for CAV1-enhanced melanoma cell migration, invasion and metastasis to the lung. Because Y14F mutation diminishes metastasis without inhibiting the tumor suppressor function of CAV1, Y14 phosphorylation emerges as an attractive therapeutic target to prevent metastasis without altering beneficial traits of CAV1.

The non-receptor tyrosine phosphatase type 14 blocks caveolin-1-enhanced cancer cell metastasis

“…Phosphorylation of CAV1 on Y14 is relevant in this context and has been related to increases in anchorageindependent growth, Grb7-dependent cell migration [34], metalloproteinase activation, and cell invasion [35], membrane microdomain internalization regulated by integrins [26] as well as caveolae formation induced by EGF [36]. Also, CAV1 expression is associated with an increase in MDA-MB-231 and B16F10 cell migration [4], which is blocked by inhibition either pharmacologically of Src family kinases with PP2 or using the non-phosphorylatable CAV1(Y14F) mutant [4,7]. Here we show that E-cadherin inhibited Y14-CAV1 Fig.…”

“…CAV1 phosphorylation on Y14 is essential to promote migration/invasion and metastatic cells have elevated levels of CAV1 pY14 in comparison to non-metastatic cancer cells [7,33]. Alternatively, the expression of E-cadherin blocks CAV1-enhanced metastasis in vivo [5].…”

“…On the one hand, CAV1 protein and mRNA levels are decreased in transformed fibroblasts, in breast, and colon cancer cell lines [1,2], and re-expression of CAV1 in colon cancer cells reduces subcutaneous tumor formation in immunosuppressed nude mice [3]. On the other hand, CAV1 acts as a promoter of metastasis in later stages of cancer, where enhanced expression of CAV1 favors the malignant phenotype and correlates with an increase in cell migration, metastasis [4][5][6][7][8], and multidrug resistance [9]. The two first mentioned roles of CAV1 are affected by the presence of the glycoprotein E-cadherin, which enhances CAV1 function as a tumor suppressor and blocks the ability of CAV1 to promote metastasis in vivo.…”

“…In metastatic breast cancer and melanoma cells, CAV1 phosphorylation on Y14 increases cell migration by promoting focal adhesion turnover, polarization, persistency, speed, and directionality of migration. All these functions of CAV1 are blocked either pharmacologically using Src family kinase inhibitors or by introducing a non-phosphorylatable CAV1 (Y14F) mutation, which also completely blocks the metastasis promoting role of CAV1 [4,7].…”

Cytoskeleton and ECM tumor mutant peptides: Increased protease sensitivities and potential consequences for the HLA class I mutant epitope reservoir

“…[8][9][10] Considering the possibility of physical barriers, or the degradation of physical barriers in relation to metastasis further suggests considering the possibility that abnormal, [11][12][13][14] or abnormally expressed 15,16 cell shape and ECM proteins could facilitate metastasis. [17][18][19] As it turns out, proteins that participate in the formation of the cytoskeleton and extracellular matrix (CECMPs) represent very large coding regions and thereby are frequently mutated in tumorigenesis, 20,21 that is, the random nature of mutagenesis makes it inevitable that many of these coding regions will be mutated. In some cases, particularly in melanoma, these coding regions have been shown to be candidate drivers.…”