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J Exp Clin Cancer Res. 2018 Jul 11;37(1):146. doi: 10.1186/s13046-018-0796-1.

Simultaneous E-cadherin and PLEKHA7 expression negatively affects E-cadherin/EGFR mediated ovarian cancer cell growth.

Author information

1
Unit of Molecular Therapies, Department of Research, Via Amadeo 42, 20133, Milan, Italy.
2
Genomics, Department of Applied Research and Technology Development, Via Amadeo 42, 20133, Milan, Italy.
3
Gynecology Oncology Unit, Department of Surgery, Via Amadeo 42, 20133, Milan, Italy.
4
Unit of Anatomic Pathology I, Deparment of Anatomic Pathology, Fondazione IRCCS Istituto Nazionale dei Tumori, Via Amadeo 42, 20133, Milan, Italy.
5
Department of Regenerative Medicine and Cell Biology, Medical University of South Carolina, 173 Ashley Avenue, Charleston, SC, 29425, USA.
6
Present address: Telethon Institute for Gene Therapy (SR-TIGET), Division of Regenerative Medicine, Stem Cells and gene Therapy, IRCCS San Raffaele Scientific Institute, Via Olgettina 60, 20132, Milan, Italy.
7
Department of Cancer Biology, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.
8
Mayo Clinic Comprehensive Cancer Center, Mayo Clinic, 4500 San Pablo Road, Jacksonville, FL, 32224, USA.
9
Unit of Molecular Therapies, Department of Research, Via Amadeo 42, 20133, Milan, Italy. antonella.tomassetti@istitutotumori.mi.it.

Abstract

BACKGROUND:

The disruption of E-cadherin-mediated adhesion is considered an important driver of tumor progression. Nevertheless, numerous studies have demonstrated that E-cadherin promotes growth- or invasion-related signaling, contrary to the prevailing notion. During tumor progression, epithelial ovarian cancer (EOC) maintains E-cadherin expression and can positively affect EOC cell growth by contributing to PI3K/AKT activation. In polarized epithelia PLEKHA7, a regulator of the zonula adherens integrity, impinges E-cadherin functionality, but its role in EOCs has been never studied.

METHODS:

Ex-vivo EOC cells and cell lines were used to study E-cadherin contribution to growth and EGFR activation. The expression of the proteins involved was assessed by real time RT-PCR, immunohistochemistry and western blotting. Cells growth and drug susceptibility was monitored in different 3-dimensional (3D) systems. Recombinant lentivirus-mediated gene expression, western blotting, immunoprecipitation and confocal microscopy were applied to investigate the biological impact of PLEKHA7 on E-cadherin behaviour. The clinical impact of PLEKHA7 was determined in publicly available datasets.

RESULTS:

We show that E-cadherin expression contributes to growth of EOC cells and forms a complex with EGFR thus positively affecting ligand-dependent EGFR/CDK5 signaling. Accordingly, 3D cultures of E-cadherin-expressing EOC cells are sensitive to the CDK5 inhibitor roscovitine combined with cisplatin. We determined that PLEKHA7 overexpression reduces the formation of E-cadherin-EGFR complex, EGFR activation and cell tumorigenicity. Clinically, PLEKHA7 mRNA is statistically decreased in high grade EOCs respect to low malignant potential and low grade EOCs and correlates with better EOC patient outcome.

CONCLUSIONS:

These data represent a significant step towards untangling the role of E-cadherin in EOCs by assessing its positive effects on EGFR/CDK5 signaling and its contribution to cell growth. Hence, the inhibition of this signaling using a CDK5 inhibitor exerts a synergistic effect with cisplatin prompting on the design of new therapeutic strategies to inhibit growth of EOC cells. We assessed for the first time in EOC cells that PLEKHA7 induces changes in the asset of E-cadherin-containing cell-cell contacts thus inhibiting E-cadherin/EGFR crosstalk and leading to a less aggressive tumor phenotype. Accordingly, PLEKHA7 levels are lower in high grade EOC patient tumors and EOC patients with better outcomes display higher PLEKHA7 levels.

KEYWORDS:

CDK5; E-cadherin; EGFR; Epithelial ovarian cancer; PLEKHA7

PMID:
29996940
PMCID:
PMC6042237
DOI:
10.1186/s13046-018-0796-1
[Indexed for MEDLINE]
Free PMC Article

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