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Role of KCNMA1 gene in breast cancer invasion and metastasis to brain.

ABSTRACT: The prognosis for patients with breast tumor metastases to brain is extremely poor. Identification of prognostic molecular markers of the metastatic process is critical for designing therapeutic modalities for reducing the occurrence of metastasis. Although ubiquitously present in most human organs, large-conductance calcium- and voltage-activated potassium channel (BKCa) channels are significantly upregulated in breast cancer cells. In this study we investigated the role of KCNMA1 gene that encodes for the pore-forming alpha-subunit of BKCa channels in breast cancer metastasis and invasion.We performed Global exon array to study the expression of KCNMA1 in metastatic breast cancer to brain, compared its expression in primary breast cancer and breast cancers metastatic to other organs, and validated the findings by RT-PCR. Immunohistochemistry was performed to study the expression and localization of BKCa channel protein in primary and metastatic breast cancer tissues and breast cancer cell lines. We performed matrigel invasion, transendothelial migration and membrane potential assays in established lines of normal breast cells (MCF-10A), non-metastatic breast cancer (MCF-7), non-brain metastatic breast cancer cells (MDA-MB-231), and brain-specific metastatic breast cancer cells (MDA-MB-361) to study whether BKCa channel inhibition attenuates breast tumor invasion and metastasis using KCNMA1 knockdown with siRNA and biochemical inhibition with Iberiotoxin (IBTX).The Global exon array and RT-PCR showed higher KCNMA1 expression in metastatic breast cancer in brain compared to metastatic breast cancers in other organs. Our results clearly show that metastatic breast cancer cells exhibit increased BKCa channel activity, leading to greater invasiveness and transendothelial migration, both of which could be attenuated by blocking KCNMA1.Determining the relative abundance of BKCa channel expression in breast cancer metastatic to brain and the mechanism of its action in brain metastasis will provide a unique opportunity to identify and differentiate between low grade breast tumors that are at high risk for metastasis from those at low risk for metastasis. This distinction would in turn allow for the appropriate and efficient application of effective treatments while sparing patients with low risk for metastasis from the toxic side effects of chemotherapy.

SUBMITTER: Khaitan D

PROVIDER: S-EPMC2727533 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature

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Role of KCNMA1 gene in breast cancer invasion and metastasis to brain.

Khaitan Divya D Sankpal Umesh T UT Weksler Babette B Meister Edward A EA Romero Ignacio A IA Couraud Pierre-Olivier PO Ningaraj Nagendra S NS

BMC cancer 20090729

<h4>Background</h4>The prognosis for patients with breast tumor metastases to brain is extremely poor. Identification of prognostic molecular markers of the metastatic process is critical for designing therapeutic modalities for reducing the occurrence of metastasis. Although ubiquitously present in most human organs, large-conductance calcium- and voltage-activated potassium channel (BKCa) channels are significantly upregulated in breast cancer cells. In this study we investigated the role of K ...[more]

PMID: 19640305

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Project description:Breast cancer is the most common malignancy among women worldwide, and the main cause of death in patients with breast cancer is metastasis. Metastasis to the central nervous system occurs in 10% to 16% of patients with metastatic breast cancer, and this rate has increased because of recent advancements in systemic chemotherapy. Because of the various treatments available for brain metastasis, accurate diagnosis and evaluation for treatment are important. Magnetic resonance imaging (MRI) is one of the most reliable preoperative examinations not only for diagnosis of metastatic brain tumors but also for estimation of the molecular characteristics of the tumor based on radiographic information such as the number of lesions, solid or ring enhancement, and cyst formation. Surgical resection continues to play an important role in patients with a limited number of brain metastases and a relatively good performance status. A single brain metastasis is a good indication for surgical treatment followed by radiation therapy to obtain longer survival. Surgical removal is also considered for two or more lesions if neurological symptoms are caused by brain lesions of >3 cm with a mass effect or associated hydrocephalus. Although maximal safe resection with minimal morbidity is ideal in the surgical treatment of brain tumors, supramarginal resection can be achieved in select cases. With respect to the resection technique, en bloc resection is generally recommended to avoid leptomeningeal dissemination induced by piecemeal resection. An operating microscope, neuronavigation, and intraoperative neurophysiological monitoring are essential in modern neurosurgical procedures, including tumor resection. More recently, supporting surgical instruments have been introduced. The use of endoscopic surgery has dramatically increased, especially for intraventricular lesions and in transsphenoidal surgery. An exoscope helps neurosurgeons to comfortably operate regardless of patient positioning or anatomy. A tubular retractor can prevent damage to the surrounding brain tissue during surgery and is a useful instrument in combination with both an endoscope and exoscope. Additionally, 5-aminolevulinic acid (5-ALA) is a promising reagent for photodynamic detection of residual tumor tissue. In the near future, novel treatment options such as high-intensity focused ultrasound (HIFU), laser interstitial thermal therapy (LITT), oncolytic virus therapy, and gene therapy will be introduced.

Dataset Information

Role of KCNMA1 gene in breast cancer invasion and metastasis to brain.

Publications

Role of KCNMA1 gene in breast cancer invasion and metastasis to brain.

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