Table 1 Protein signal pathway correlates of breast pCR
Analyte | Treatment arm (Baseline/Day 14) | Reverse phase protein microarray results | Interpretation | ||
|---|---|---|---|---|---|
pCR Breast Yes | pCR | p Value <0.05 | |||
Breast No | |||||
EGFR Tyr1068 | Lapatinib arm Baseline | Mean: | Mean: | p = 0.02c | Phosphorylation of EGFR at Tyrosine 1068 occurs during receptor activation, leading to downstream activation of growth and pro-survival pathway proteins. |
-0.66 | -0.01 | ||||
(n = 6) | (n = 11) | ||||
FOXO1/03A Ratios | All treatment arms Baseline | FOXO is a transcription factor that functions as a tumor suppressor. FOXO triggers cell cycle arrest and apoptosis after it enters the nucleus. Phosphorylation of FOXO (pFOXO) causes export from the nucleus and inactivates its tumor suppressor function. Trastuzumab inhibits HER2+ cells by reactivation of FOXO1A [15] | |||
pPTEN:pFOXO | Mean ratio: 2.79 | Mean ratio: 0.04 | p = 0.01b | ||
(n = 27) | (n = 22) | ||||
PI3K:pFOXO | Mean ratio: 3.23 (n = 27) | Mean ratio | p = 0.039 | ||
-0.2 (n = 22) | |||||
pStat5 Tyr694 | Trastuzumab arm day 14 | Mean: | Mean: | p = 0.017b | Stat5 is a transcription factor. After phosphorylation by JAK2, pStat5 translocates to the nucleus to initiate transcription of e-cadherin, which promotes homotypic adherence between breast cells and basement membrane, i.e., normal behavior. Absent nuclear pStat5 is a negative prognostic factor [16, 17]. Increased pStat indicates transcription functionality in our pCR subjects. |
1.14 | -0.49 | ||||
(n = 11) | (n = 9) | ||||
Protein linkage correlation analysisa | All treatment arms Baseline | Autophagy is a normal cellular process to promote cell survival under stress (hypoxia, nutrient deprivation, loss of adhesion). Autophagy allows the cell to “self eat” to generate ATP from cellular contents and thereby survive in times of stress, starvation, hypoxia, or chemotherapy. Autophagy is regulated by a network of cell signaling proteins, including mTOR, Beclin (upstream markers), Bcl2, LC3B (downstream markers), Atg5. Cells from patients classified as pCR No appear to engage autophagy to survive in the presence of treatment with trastuzumab, lapatinib or the combination [18]. | |||
LC3B-Beclin | LC3B-Beclin 1 SR = 0.88 | p < 0.001 | |||
LC3B-MMP14 | LC3B-MMP14 | p < 0.001 | |||
SR = 0.83 | |||||
LC3B-Her2 | LC3B-HER2 | p < 0.001 | |||
SRa = 0.88 | |||||
LC3B-Stat5 Tyr694 | LC3B-pStat5 | p < 0.001 | |||
SR = 0.84 | |||||