Suberoylanilide hydroxamic acid blocks self-renewal and homotypic aggregation of inflammatory breast cancer spheroids.
BACKGROUND
Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer (LABC). Patients with IBC commonly present with skin metastasis, which are observed microscopically as tumor emboli within dermal lymphatics. These metastatic tumor cells aberrantly overexpress E-cadherin and exhibit the ability to undergo self-renewal and are highly invasive. There are no therapeutics yet identified that target the structure and functions of IBC tumor emboli. The present studies evaluated the effects of the pan-histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) using IBC tumor spheroids derived from established IBC cell lines and tumor spheroids derived from pleural effusion (PE) aspirates of patients with IBC and LABC, designated as PE-IBC and PE-LABC.


METHODS
Methods used are as follows: culture of IBC cells from clonal density single cells in low adherence culture conditions that promote formation of IBC tumor spheroids; clonogenic assays; cell fractionation and Western blotting; confocal microscropy; and modified Boyden chamber invasion assays.


RESULTS
SAHA inhibited self-renewal of IBC tumor spheroids from established IBC cell lines and PE-IBC and PE-LABC, as assessed by decreased clonogenic growth. SAHA blocked homotypic aggregation of the cells that comprised the IBC tumor spheroids leading to loss of their 3-dimensional (3D) structure, which was associated with a change in location of E-cadherin protein from the plasma membrane in untreated IBC tumor spheroids to the cytoplasm of cells within IBC tumor spheroids with SAHA treatment. In addition, SAHA blocked the robust invasion exhibited by IBC tumor spheroids of established cell lines as well as by tumor spheroids derived from PE-IBC and PE-LABC.


CONCLUSIONS
SAHA targets the integrity and biological activities of IBC tumor spheroids and may be a promising agent to evaluate for its effectiveness in treatment of IBC.
Robertson
Fredika M
FM
The Morgan Welch Inflammatory Breast Cancer Research Program, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA. frobertson@mdanderson.org
Woodward
Wendy A
WA
Pickei
Ross
R
Ye
Zaiming
Z
Bornmann
William
W
Pal
Ashutosh
A
Peng
Zhenghong
Z
Hall
Carolyn S
CS
Cristofanilli
Massimo
M
D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D015820:Cadherins / Q000032:analysis; D002449:Cell Aggregation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D004353:Drug Evaluation, Preclinical; D005260:Female; D056572:Histone Deacetylase Inhibitors / Q000494:pharmacology; D006801:Humans; D006877:Hydroxamic Acids / Q000494:pharmacology*; D007249:Inflammation / Q000188:drug therapy; D009361:Neoplasm Invasiveness / Q000517:prevention & control; D018874:Spheroids, Cellular; D000077337:Vorinostat
D000970:Antineoplastic Agents; D015820:Cadherins; D056572:Histone Deacetylase Inhibitors; D006877:Hydroxamic Acids; D000077337:Vorinostat