During embryonic development, cells are tasked with the critical functions of growth, expansion, and migration to form tissues and organs in a meticulously orchestrated manner. This intricate process is governed by numerous intracellular pathways—specifically, complex signaling cascades within a cell—that aim to ensure controlled growth and prevent unregulated proliferation, which could lead to malformations or cancers. A significant pathway involved in these regulatory mechanisms is the PTEN/PI3K axis, representing a sophisticated network of chemical processes designed to maintain balance and homeostasis within cellular environments.
The PTEN gene, when mutated, often results in the overactivity of PI3K. This disruption creates an imbalance within the signaling pathway, potentially leading to the initiation of various cancer types such as breast and prostate cancers. Particularly concerning is the hereditary aspect of PTEN mutations, where germline alterations can give rise to a range of disorders collectively termed PTEN Hamartoma Tumor Syndrome (PHTS). This syndrome manifests a heterogeneous spectrum of clinical symptoms that remain largely underexplored, largely due to the limited understanding of its underlying mechanisms. Such gaps in knowledge have hindered the development of preclinical models and innovative molecular therapies for affected patients.
Researchers have established that mutations in the PI3K pathway specifically impacting endothelial cells, which line the interior of blood vessels, lead to the development of various vascular malformations. Strikingly, studies suggest that nearly 50% of patients diagnosed with PHTS exhibit significant vascular abnormalities during early childhood. These malformations are often symptomatic, leading to debilitating pain and swelling, with surgical interventions and embolization—strategies that involve blocking affected blood vessels—serving as the primary modes of treatment. However, the feasibility of these interventions is highly variable, contingent on the specific characteristics and localization of the vascular lesions, often leaving patients with limited therapeutic options.
A dedicated research group focused on this issue is the Endothelial Pathobiology and Microenvironment division at the Josep Carreras Institute. Led by Dr. Mariona Graupera, along with the contributions of Dr. Sandra Castillo and Dr. Eulàlia Baselga, the team has delved into the genetic etiology of vascular malformations associated with PHTS. By conducting detailed analyses of patient biopsies and derived endothelial cell lines, they have made a groundbreaking discovery: PHTS patients typically possess a non-functional copy of the PTEN gene in place of a functional one—an event described as “uniparental disomy.” This finding, derived from experiments conducted in murine models, elucidates many of the subsequent vascular consequences observed in affected individuals, thus providing invaluable insights into PHTS.
Recently published in the esteemed journal Cancer Discovery, this research marks a pivotal advancement in the understanding and management of PHTS-related vascular malformations. Through their findings, the research team has successfully established the first mouse model indicative of PHTS vascular anomalies. This model serves as a crucial foundation for studying the therapeutic potential of two anticancer drugs capable of countering the dysregulated activities of the PI3K pathway, effectively mimicking the regulatory role that PTEN would typically exert in healthy tissue.
The studies showcased significant results, where employing inhibitors like rapamycin or capivasertib to block downstream components of the PI3K signaling cascade led to a marked reduction in vascular growth. In stark contrast, the targeted inhibition of PI3K using alpelisib yielded little to no therapeutic benefit. Furthermore, this research provides compelling evidence through proof-of-concept cases, wherein two patients exhibiting PHTS received off-label treatment with rapamycin. Remarkably, these patients demonstrated significant reductions in vascular overgrowth, alongside alleviation of pain linked to associated lesions.
The implications of this groundbreaking research extend far beyond a mere academic exercise; the potential to halt the vascular ramifications associated with PHTS from the onset signifies a crucial avenue for enhancing patient outcomes and quality of life. Traditionally, the diagnosis of PHTS tends to occur in adults, often when cancer has already manifested. However, since vascular malformations present in early childhood, this condition opens up an exceptional clinical window for timely diagnosis and intervention.
Funding for this transformative research has been generously provided by the PTEN Research Foundation, in conjunction with the Spanish Ministry of Science, Innovation and Universities and the “la Caixa” Foundation. The collaborative effort underscores the urgency of further investigation into PHTS, particularly given the broad spectrum of clinical challenges encountered by patients and the immediate need for practical therapeutic applications.
The complex interplay of genetics, cellular pathways, and clinical manifestations highlighted by this research illustrates the multifaceted nature of PHTS and the critical role of enhanced scientific understanding in fostering improved treatment strategies. As the field of cancer research advances, we are reminded of the potential that exists for transformative therapies to emerge from rigorous scientific investigation, underscoring the compelling need for continued support, funding, and exploration in the realm of rare diseases like PHTS.
In conclusion, the ongoing journey of research into the genetic underpinnings of PTEN Hamartoma Tumor Syndrome epitomizes a beacon of hope for patients and families grappling with the challenges posed by this complex disorder. With a deeper understanding of the genetics involved, coupled with an integration of innovative therapeutic strategies, the prospects for effectively managing and treating PHTS-related vascular malformations appear increasingly promising.
Subject of Research: Animals
Article Title: Somatic uniparental disomy of PTEN in endothelial cells causes vascular malformations in patients with PTEN Hamartoma Tumor Syndrome
News Publication Date: 28-Mar-2025
Web References: 10.1158/2159-8290.CD-24-0807
References: N/A
Image Credits: Josep Carreras Leukaemia Research Institute
Keywords: Endothelial cells, PTEN, PI3K, Vascular malformations, Cancer Discovery, Research, PHTS, Genetic study, Therapeutic strategies
Tags: cancer initiation mechanismsclinical symptoms of PHTSconventional anticancer therapiesembryonic cell developmentendothelial cell mutationshereditary cancer syndromesmolecular therapies for cancerPI3K signaling pathwaypreclinical models in cancer researchPTEN gene mutationsPTEN Hamartoma Tumor Syndrometargeted cancer treatments
