Biology subjects

Lingerak, R.

Publications and source records attributed to Lingerak, R..

3 recordsLinked to original sources

bioRxiv2024

Skeletal Metastasis of Prostate Cancer Is Augmented by Activation of EphA2 Noncanonical Signaling and Ligand-Deficient Bone Microenvironment

EphA2, a member of Eph family receptor tyrosine kinases (RTKs), is overexpressed in multiple types of solid human tumors, particularly at the late stages. However, whether and how it drives specific malignant processes remain elusive. We report that EphA2 is elevated during prostate cancer (PCa) progression in multiple syngeneic murine models. Interestingly, human metastatic PCa specimens from two Rapid Autopsy Programs showed selective overexpression of EphA2 in metastasis to the bone, but not to the lymph nodes or viscera. Serine 897 phosphorylation that mediates the pro-oncogenic, noncanonical signaling by EphA2 was also upregulated in bone metastasis. Analysis of human datasets shows EphA2 overexpression is associated with skeletal but not visceral metastases. Ephrin-A1, a major cognate ligand for EphA2, is lost in PCa bone metastasis, which is correlated with poor prognosis. Further, the bone microenvironment is unique in expressing little of the five EFNA genes, providing permissive microenvironment for bone colonization. S897A mutation that ablates EphA2 noncanonical signaling, suppressed PCa development. Restoration of ephrin-A1 expression in PC-3, a model cell line for double negative prostate cancer derived from bone metastasis and devoid of ephrin-As, profoundly changed global tyrosine phosphorylation profiles, inhibited basal ERK and Src activities in vitro, and suppressed tumor development in the bone. Together these results demonstrate EphA2 overexpression and concomitant loss of ligands in PCa lead to activation of noncanonical signaling that is sustained in ephrin-A1-deficient skeletal milieu to promote bone metastasis.

cancer biology↗

bioRxiv2023

The SAM Domain of EphA2 Inhibits Ligand-Independent Clustering and Activation

Eph receptors are the largest family of receptor tyrosine kinases (RTKs). They play a role in the pathogenesis of various diseases including cancer, atherosclerosis, fibrosis, infectious diseases, diseases of the central nervous system and age-related cataract. EphA2 has attracted much attention over the years owing to its dysregulation in many diseases. Previous studies have revealed the unique molecular organizations of Eph receptors, and particularly EphA2, into large clusters of receptor-ligand complexes. One unique feature of Eph receptors is a C-terminal sterile alpha motif (SAM) domain, which has been proposed to alter dimerization and kinase activity in EphA2. However, the precise role of the SAM domain in regulating the function and oligomerization state of EphA2 has not been reported. Here we apply a time-resolve fluorescence spectroscopy, PIE-FCCS, to characterize the oligomerization state of EphA2 in live cells and determine the role of the SAM domain. We deleted the SAM domain in the context of full length EphA2 and an intracellular domain (ICD) construct to assess the effect of the SAM domain on oligomerization state, kinase activity, and cellular behavior. Overall, we find that the SAM domain inhibits ligand-independent clustering and kinase activity in both full-length EphA2 and the isolated ICD construct at the cell membrane. These results are consistent with the autoinhibitory features of the C-terminal tail of EGFR and may help resolve the allosteric regulation of other RTKs.

biophysics↗

bioRxiv2021

Cell Surface Multimeric Assemblies Regulate Canonical and Noncanonical EphA2 Receptor Tyrosine Kinase Signaling

The EphA2 receptor tyrosine kinase mediates ligand-induced canonical signaling associated with tumor suppression and ligand-independent noncanonical signaling implicated in tumor progression. Using time-resolved fluorescence spectroscopy in live cells, we find that unliganded EphA2 receptors pre-assemble into multimers, which is mediated by two symmetric and one asymmetric interfaces in the ectodomain. Upon ligand binding, EphA2 receptors are further assemble into large clusters that also requires the three interfaces. Functionally, disrupting either the symmetric or asymmetric contacts individually blocks the autorecycling of the EphA2 apo receptor. However, only symmetric contact disruption promotes noncanonical signaling and inhibits ligand-induced catalytic activation and endocytosis, which are associated with increased cell migration in vitro and reduced survival in a syngeneic murine glioblastoma model. Our results reveal the pivotal role of EphA2 assembly in dictating canonical vs. noncanonical signaling, and identify the precise molecular interfaces that mediate the formation of the EphA2 signaling clusters.

biophysics↗