Cell Adhesion-Linked Protein Tyrosine Phosphatases and Breast Cancer Metastasis
Abstract
21 "CLASSICAL" PROTEIN TYROSINE PHOSPHATASES (PTPs) were identified in human mammary epithelial cell (MEC) lines. Degenerate RT-PCR followed by restriction fragment differential display (RFDD) and specific RT-PCR were used to assess expression in the continuous HMT-3522 cell series that includes both non-malignant Si and tumorigenic T4-2 cells in monolayer and during normal and dysregulated morphogenesis in EHS-ECM (Matrigel). PTP expression was generally higher in tumorigenic T4-2 cells and unchanged by disorganized growth in Matigel. in contrast, coordination of expression was suggested by the transient upregulation (relative to monolayer cultures) of a number of PTPs during acinar morphogenesis of non-malignant Si. The kinetics of downregulation for some suggested that growth arrest may be the main regulatory input. Others however, downregulate with more rapid kinetics before significant growth arrest suggesting different regulatory inputs. Feedback from of cell-cell adherens junctions (AJ) may be one such input as ectopic expression of a dominant negative E-cadherin construct that blocks AJ formation delayed but did not prevent downregulation of selected PTPs. Modest upregulation of actin cytoskeleton regulating PTPs in response to decreases in substrate compliancy occur when normal MCF10A were plated on (^1 order of magnitude) softer (tissue-like) Matrigel coupled polyacrylamide gels suggesting that these PTPs may be responding to, or mediating corresponding actin cytoskeletal reaorganization. PTPN12 is a cytoplasmic PTP highly expressed in MECs that localizes transiently to actin polymerizing zones including lamellopodial leading edges and the metaphase mitotic spindle and plasma membrane. Stable downregulation of PTPN12 by retroviral mediated shRNAi resulted in derangements of the actin cytoskeleton in MCF10A cells. These cells grew more rapidly and formed larger but normally polarized acini in Matrigel.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 2004
- Accession Number
- ADA428191
Entities
People
- Johnathon N. Lakins
- Valerie M Weaver
Organizations
- University of Pennsylvania