Deletion of PTEN promotes tumorigenic signaling, resistance to anoikis, and altered response to chemotherapeutic agents in human mammary epithelial cells.
Many cancers, including breast cancer, harbor loss-of-function mutations in the catalytic domain of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) or have reduced PTEN expression through loss of heterozygosity and/or epigenetic silencing mechanisms. However, specific phenotypic effects of PTEN inactivation in human cancer cells remain poorly defined without a direct causal connection between the loss of PTEN function and the development or progression of cancer. To evaluate the biological and clinical relevance of reduced or deleted PTEN expression, a novel in vitro model system was generated using human somatic cell knockout technologies. Targeted homologous recombination allowed for a single and double allelic deletion, which resulted in reduced and deleted PTEN expression, respectively. We determined that heterozygous loss of PTEN in the nontumorigenic human mammary epithelial cell line MCF-10A was sufficient for activation of the phosphoinositide 3-kinase/AKT and mitogen-activated protein kinase pathways, whereas the homozygous absence of PTEN expression led to a further increased activation of both pathways. The deletion of PTEN was able to confer growth factor-independent proliferation, which was confirmed by the resistance of the PTEN(-/-) MCF-10A cells to small-molecule inhibitors of the epidermal growth factor receptor. However, neither heterozygous nor homozygous loss of PTEN expression was sufficient to promote anchorage-independent growth, but the loss of PTEN did confer apoptotic resistance to cell rounding and matrix detachment. Finally, MCF-10A cells with the reduction or loss of PTEN showed increased susceptibility to the chemotherapeutic drug doxorubicin but not paclitaxel.
University of Maryland Greenebaum Cancer Center, University of Maryland School of Medicine, Baltimore, Maryland 21201, USA. mvitolo@umaryland.edu
Michele I
MI
Vitolo
Michele B
MB
Weiss
Marta
M
Szmacinski
Khola
K
Tahir
Todd
T
Waldman
Ben Ho
BH
Park
Stuart S
SS
Martin
David J
DJ
Weber
Kurtis E
KE
Bachman
D023102:Anoikis; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002070:Butadienes / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002471:Cell Transformation, Neoplastic / Q000473:pathology*; D002867:Chromones / Q000494:pharmacology; D004317:Doxorubicin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D019426:Integrases / Q000378:metabolism; D042361:Mammary Glands, Human / Q000187:drug effects* / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D009025:Morpholines / Q000494:pharmacology; D009570:Nitriles / Q000494:pharmacology; D051059:PTEN Phosphohydrolase / Q000502:physiology*; D017239:Paclitaxel / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction
D000903:Antibiotics, Antineoplastic; D000972:Antineoplastic Agents, Phytogenic; D002070:Butadienes; D002867:Chromones; D004791:Enzyme Inhibitors; D009025:Morpholines; D009570:Nitriles; D012333:RNA, Messenger; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D004317:Doxorubicin; D019869:Phosphatidylinositol 3-Kinases; D051057:Proto-Oncogene Proteins c-akt; D020928:Mitogen-Activated Protein Kinases; C045073:Cre recombinase; D019426:Integrases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D017239:Paclitaxel