Sushi domain containing 3 (SUSD3) and its role in breast cancer cell morphology, migration, and adhesion

Abstract

ObjectiveAromatase inhibitors (AIs) have become the mainstay of the endocrine treatment of postmenopausal breast cancer and we have identified SUSD3 to be down-regulated in AI non-responsive patients. We previously demonstrated a direct regulatory role of ERα in SUSD3 expression with localization of SUSD3 to the outer cellular membrane. We hypothesized a possible role of SUSD3 in breast cancer cell-to-cell adhesion and/or migration.DesignBasic science research.Materials and MethodsMCF7 breast cancer cells were transfected with siRNA targeting SUSD3 or a control siRNA. Morphological changes were documented by phase contrast microscopy 48 and 72 hours post-transfection. Western blot analyses for focal adhesion kinase (FAK), Src, and phosphorylated paxillin (p-Pax) were performed after 72 hr of siRNA transfection. Wound healing, dispase, and aggregation assays were performed after 72hr siRNA transfections and results were documented by phase contrast microscopy.ResultsMorphological changes, including decreased presence of lamellipodia and filopodia, were observed in SUSD3 knockdown cells as compared to control at 48 hours. FAK and p-Pax protein levels were increased in SUSD3 knockdown cells as compared to control. Wound healing experiments revealed decreased motility (measured as % wound open) in SUSD3 knockdown cells (95% ± 4%) as compared to control (56% ± 4%). Dispase and aggregation assays revealed decreased cell-to-cell adhesion strength in SUSD3 knockdown cells compared to control.ConclusionIn conclusion, SUSD3 protein appears to play a role in breast cancer cell function as loss leads to decreased motility and adhesion. SUSD3 may be a key functional protein in the metastatic pathway and may prove to be a possible therapeutic target in breast cancer. ObjectiveAromatase inhibitors (AIs) have become the mainstay of the endocrine treatment of postmenopausal breast cancer and we have identified SUSD3 to be down-regulated in AI non-responsive patients. We previously demonstrated a direct regulatory role of ERα in SUSD3 expression with localization of SUSD3 to the outer cellular membrane. We hypothesized a possible role of SUSD3 in breast cancer cell-to-cell adhesion and/or migration. Aromatase inhibitors (AIs) have become the mainstay of the endocrine treatment of postmenopausal breast cancer and we have identified SUSD3 to be down-regulated in AI non-responsive patients. We previously demonstrated a direct regulatory role of ERα in SUSD3 expression with localization of SUSD3 to the outer cellular membrane. We hypothesized a possible role of SUSD3 in breast cancer cell-to-cell adhesion and/or migration. DesignBasic science research. Basic science research. Materials and MethodsMCF7 breast cancer cells were transfected with siRNA targeting SUSD3 or a control siRNA. Morphological changes were documented by phase contrast microscopy 48 and 72 hours post-transfection. Western blot analyses for focal adhesion kinase (FAK), Src, and phosphorylated paxillin (p-Pax) were performed after 72 hr of siRNA transfection. Wound healing, dispase, and aggregation assays were performed after 72hr siRNA transfections and results were documented by phase contrast microscopy. MCF7 breast cancer cells were transfected with siRNA targeting SUSD3 or a control siRNA. Morphological changes were documented by phase contrast microscopy 48 and 72 hours post-transfection. Western blot analyses for focal adhesion kinase (FAK), Src, and phosphorylated paxillin (p-Pax) were performed after 72 hr of siRNA transfection. Wound healing, dispase, and aggregation assays were performed after 72hr siRNA transfections and results were documented by phase contrast microscopy. ResultsMorphological changes, including decreased presence of lamellipodia and filopodia, were observed in SUSD3 knockdown cells as compared to control at 48 hours. FAK and p-Pax protein levels were increased in SUSD3 knockdown cells as compared to control. Wound healing experiments revealed decreased motility (measured as % wound open) in SUSD3 knockdown cells (95% ± 4%) as compared to control (56% ± 4%). Dispase and aggregation assays revealed decreased cell-to-cell adhesion strength in SUSD3 knockdown cells compared to control. Morphological changes, including decreased presence of lamellipodia and filopodia, were observed in SUSD3 knockdown cells as compared to control at 48 hours. FAK and p-Pax protein levels were increased in SUSD3 knockdown cells as compared to control. Wound healing experiments revealed decreased motility (measured as % wound open) in SUSD3 knockdown cells (95% ± 4%) as compared to control (56% ± 4%). Dispase and aggregation assays revealed decreased cell-to-cell adhesion strength in SUSD3 knockdown cells compared to control. ConclusionIn conclusion, SUSD3 protein appears to play a role in breast cancer cell function as loss leads to decreased motility and adhesion. SUSD3 may be a key functional protein in the metastatic pathway and may prove to be a possible therapeutic target in breast cancer. In conclusion, SUSD3 protein appears to play a role in breast cancer cell function as loss leads to decreased motility and adhesion. SUSD3 may be a key functional protein in the metastatic pathway and may prove to be a possible therapeutic target in breast cancer.