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Supplementary Information, Methods, Table 1, Figures 1-7 from 3-Phosphoinositide–Dependent Kinase 1 Potentiates Upstream Lesions on the Phosphatidylinositol 3-Kinase Pathway in Breast Carcinoma

Lesions of ERBB2, PTEN, and PIK3CA activate the phosphatidylinositol 3-kinase (PI3K) pathway during cancer development by increasing levels of phosphatidylinositol-3,4,5-triphosphate (PIP3). 3-Phosphoinositide-dependent kinase 1 (PDK1) is the first node of the PI3K signal output and is required for activation of AKT. PIP3 recruits PDK1 and AKT to the cell membrane through interactions with their pleckstrin homology domains, allowing PDK1 to activate AKT by phosphorylating it at residue threonine-308. We show that total PDK1 protein and mRNA were overexpressed in a majority of human breast cancers and that 21% of tumors had five or more copies of the gene encoding PDK1, PDPK1. We found that increased PDPK1 copy number was associated with upstream pathway lesions (ERBB2 amplification, PTEN loss, or PIK3CA mutation), as well as patient survival. Examination of an independent set of breast cancers and tumor cell lines derived from multiple forms of human cancers also found increased PDK1 protein levels associated with such upstream pathway lesions. In human mammary cells, PDK1 enhanced the ability of upstream lesions to signal to AKT, stimulate cell growth and migration, and rendered cells more resistant to PDK1 and PI3K inhibition. After orthotopic transplantation, PDK1 overexpression was not oncogenic but dramatically enhanced the ability of ERBB2 to form tumors. Our studies argue that PDK1 overexpression and increased PDPK1 copy number are common occurrences in cancer that potentiate the oncogenic effect of upstream lesions on the PI3K pathway. Therefore, we conclude that alteration of PDK1 is a critical component of oncogenic PI3K signaling in breast cancer. [Cancer Res 2009;69(15):6299–306]

Axillary node dissection (ALND) is the standard of care for patients who have a positive sentinel lymph node (SLN) on sentinel lymph node biopsy (SLNB). We sought to identify a low-risk patient population with positive SLN that may not need cALND. We analyzed SLNB for breast cancer at our institutions between 1999 and 2007. We identified 130 patients who had a positive SLN but did not undergo completion ALND. We evaluated clinical data, adjuvant treatment patterns and intermediate locoregional and distant events. The median patient age was 50; 19% had N0(i+) disease, 53% had micrometastatic (N1mi) disease, and 28% had macrometastasis. Eighty-eight percent of patients underwent radiation therapy; 66 patients (51%) had documented nodal radiation (of these 50 were treated with three fields and 14 with high tangents. Local recurrence in the breast occurred in two patients (2%) and nine patients (7%) developed distant metastases; there were no axillary/nodal recurrences. In this highly selected group of patients who had a positive SLNB but did not undergo cALND, we observed no axillary recurrences.

Lesions of ERBB2, PTEN, and PIK3CA activate the phosphatidylinositol 3-kinase (PI3K) pathway during cancer development by increasing levels of phosphatidylinositol-3,4,5-triphosphate (PIP3). 3-Phosphoinositide-dependent kinase 1 (PDK1) is the first node of the PI3K signal output and is required for activation of AKT. PIP3 recruits PDK1 and AKT to the cell membrane through interactions with their pleckstrin homology domains, allowing PDK1 to activate AKT by phosphorylating it at residue threonine-308. We show that total PDK1 protein and mRNA were overexpressed in a majority of human breast cancers and that 21% of tumors had five or more copies of the gene encoding PDK1, PDPK1. We found that increased PDPK1 copy number was associated with upstream pathway lesions (ERBB2 amplification, PTEN loss, or PIK3CA mutation), as well as patient survival. Examination of an independent set of breast cancers and tumor cell lines derived from multiple forms of human cancers also found increased PDK1 protein levels associated with such upstream pathway lesions. In human mammary cells, PDK1 enhanced the ability of upstream lesions to signal to AKT, stimulate cell growth and migration, and rendered cells more resistant to PDK1 and PI3K inhibition. After orthotopic transplantation, PDK1 overexpression was not oncogenic but dramatically enhanced the ability of ERBB2 to form tumors. Our studies argue that PDK1 overexpression and increased PDPK1 copy number are common occurrences in cancer that potentiate the oncogenic effect of upstream lesions on the PI3K pathway. Therefore, we conclude that alteration of PDK1 is a critical component of oncogenic PI3K signaling in breast cancer. [Cancer Res 2009;69(15):6299–306]

Mucinous breast cancer is typically associated with a favorable prognosis. This study aimed to assess recent trends and prognostic features in the treatment of mucinous breast carcinoma.A retrospective review of our database of patients who presented with mucinous breast cancer was performed. We evaluated patient and tumor characteristics and examined the relationships between these factors and risk for locoregional recurrence.One hundred eleven patients with mucinous breast cancer were identified. Seventy-one (64%) underwent lumpectomy with radiotherapy. Fourteen (13%) had lymph node metastasis, and node positivity was associated with larger tumor size; node-positive patients had a mean tumor size of 2.7 cm compared with 1.5 cm for node-negative patients (P = .0003). No patients with tumor size1 cm had lymph node metastasis. Five patients (5%) had local and/or distant recurrence.Mucinous breast cancer is associated with a low recurrence rate as well as a low incidence of lymph node metastasis. In patients with small (1 cm) tumors, consideration for deferring nodal evaluation may be made.