Ubiquitin-conjugating enzyme 9 (Ubc9), the sole conjugating enzyme for sumoylation, regulates protein function and plays an important role in tumorigenesis. Whether Ubc9 is involved in the chemoresistance of breast cancer remains unknown. In this study, we aimed to evaluate the contribution of Ubc9 in the chemoresistance of breast cancer. Immunohistochemistry (IHC) was used to examine the expression level of Ubc9. Chi-square test, Wilcoxon test, and one-way ANOVA were applied to analyze the relationship between Ubc9 expression, clinicopathologic features, and clinical response to neoadjuvant chemotherapy. The significance of variables for survival was analyzed by the Cox proportional hazards model in a multivariate analysis. Kaplan-Meier survival curves were plotted and log-rank test was performed. The proportion of Ubc9-positive cells was higher in invasive ductal carcinoma than in normal breast tissues [(48.48 ± 17.94)% vs. (5.82 ± 2.80)%, P < 0.001]. High Ubc9 expression was associated with poor differentiation (Χ² = 6.538, P = 0.038), larger tumor size (Χ² = 4.701, P = 0.030), advanced clinical stage (Χ² = 4.651, P = 0.031), lymph node metastasis (Χ² = 9.913, P = 0.010), basal-like phenotype (Χ² = 8.660, P = 0.034), and poor clinical response to neoadjuvant chemotherapy (Χ² = 11.09, P = 0.001). The expected 6-year cumulative disease-free survival rate was 87.32% in patients with low Ubc9 expression compared to 68.78% in those with high Ubc9 expression (Χ² = 4.289, P = 0.038). These data indicate that high Ubc9 expression correlates with poor response to chemotherapy and poor clinical prognosis.
Adult ; Antineoplastic Combined Chemotherapy Protocols ; therapeutic use ; Breast Neoplasms ; drug therapy ; enzymology ; pathology ; surgery ; Carcinoma, Ductal, Breast ; drug therapy ; enzymology ; pathology ; surgery ; Cyclophosphamide ; therapeutic use ; Disease Progression ; Disease-Free Survival ; Drug Resistance, Neoplasm ; Epirubicin ; therapeutic use ; Female ; Fluorouracil ; therapeutic use ; Humans ; Immunohistochemistry ; Kaplan-Meier Estimate ; Lymphatic Metastasis ; Mastectomy ; methods ; Middle Aged ; Neoadjuvant Therapy ; Neoplasm Staging ; Proportional Hazards Models ; Remission Induction ; Tumor Burden ; Ubiquitin-Conjugating Enzymes ; metabolism ; Up-Regulation

OBJECTIVETo investigate the expression of extracellular signal-regulated kinase (ERK) and its relationship with clinicopathological characteristics of breast cancer as well as the effect of preoperative chemotherapy on ERK expression.

METHODSExpression of ERK-1 and ERK-2 protein was examined by Western blot in the breast cancer and normal breast (control) tissue of 48 patients, of whom 8 had received preoperative chemotherapy of 5'-deoxy-5-fluorouridine (5'-DFUR), with distribution of ERKs protein detected by immunohistochemical method.

RESULTSExpression of ERK-1 and ERK-2 protein was increased in tumor specimen as compared with control tissue (P < 0.01). A positive correlation was observed between ERK-1 and ERK-2 (r = 0.457, P < 0.01). Protein level of ERK-1 and ERK-2 was higher in stage III patients than in stage I and stage II patients (P < 0.05). Expression of both ERK-1 and ERK-2 in the carcinoma tissue was decreased in patients who had received preoperative chemotherapy of 5'-DFUR. ERK-1 and ERK-2 proteins were mainly located in the cytoplasm.

CONCLUSIONThe hyperexpression of ERK may play an important role in the initiation and development of human breast cancer. Preoperative chemotherapy of 5'-DFUR is able to partially inhibit ERK expression.

Antimetabolites, Antineoplastic ; therapeutic use ; Breast Neoplasms ; classification ; drug therapy ; enzymology ; pathology ; Female ; Floxuridine ; therapeutic use ; Humans ; Mitogen-Activated Protein Kinase 1 ; biosynthesis ; Mitogen-Activated Protein Kinase 3 ; Mitogen-Activated Protein Kinases ; biosynthesis ; Neoplasm Staging

Radiation and drug resistance remain the major challenges and causes of mortality in the treatment of locally advanced, recurrent and metastatic breast cancer. Dysregulation of phospholipase D (PLD) has been found in several human cancers and is associated with resistance to anticancer drugs. In the present study, we evaluated the effects of PLD inhibition on cell survival, cell death and DNA damage after exposure to ionizing radiation (IR). Combined IR treatment and PLD inhibition led to an increase in the radiation-induced apoptosis of MDA-MB-231 metastatic breast cancer cells. The selective inhibition of PLD1 and PLD2 led to a significant decrease in the IR-induced colony formation of breast cancer cells. Moreover, PLD inhibition suppressed the radiation-induced activation of extracellular signal-regulated kinase and enhanced the radiation-stimulated phosphorylation of the mitogen-activated protein kinases p38 and c-Jun N-terminal kinase. Furthermore, PLD inhibition, in combination with radiation, was very effective at inducing DNA damage, when compared with radiation alone. Taken together, these results suggest that PLD may be a useful target molecule for the enhancement of the radiotherapy effect.
Breast Neoplasms/*drug therapy/*enzymology/pathology ; Cell Death/drug effects/radiation effects ; Cell Line, Tumor ; Cell Proliferation/drug effects/radiation effects ; DNA Damage ; Enzyme Activation/drug effects/radiation effects ; Enzyme Inhibitors/*pharmacology/*therapeutic use ; Extracellular Signal-Regulated MAP Kinases/metabolism ; Female ; Humans ; JNK Mitogen-Activated Protein Kinases/metabolism ; Phospholipase D/*antagonists & inhibitors/metabolism ; Radiation Tolerance/*drug effects ; Radiation, Ionizing ; p38 Mitogen-Activated Protein Kinases/metabolism