[The expression of Plakoglobin in residual cancer after neoadjuvant chemotherapy for breast cancer and its prognostic impact on patients].

Objective: To investigate the relationship between the expression levels of Plakoglobin protein in residual lesions after neoadjuvant chemotherapy (NAC) and the prognosis of breast cancer patients. Methods: Clinical and pathological data from 174 breast cancer patients who underwent surgery after receiving NAC at the Cancer Hospital of Chinese Academy of Medical Sciences from January 2009 to December 2017 were collected. The expression level of Plakoglobin in residual cancer lesions was evaluated by immunohistochemistry. The correlation between Plakoglobin expression level and clinicopathological features was analyzed. Survival analysis was performed using the Kaplan-Meier method, and Cox proportional hazard regression models were used for factor analysis. Results: Among the 174 patients, 140 had low expression of Plakoglobin, and 34 had high expression. The median disease-free survival (DFS) and overall survival (OS) in the Plakoglobin low expression group were 59.46 and 71.68 months, respectively, both of which were higher than those in the high expression group (36.58 and 47.26 months, respectively, both P<0.05). Univariate analysis showed that Plakoglobin expression, pathological N stage, lymphovascular invasion status, histological grade, Ki-67, and molecular subtypes were associated with OS (all P<0.05), while pathological N stage, histological grade, and Ki-67 were associated with DFS (all P<0.05). Multivariate analysis revealed that Plakoglobin expression (HR=2.438, 95% CI: 1.256-4.735, P=0.008) was an independent predictor for OS, and Ki-67 (HR=2.228, 95% CI: 1.316-3.773, P=0.003) was an independent predictor for DFS. Conclusion: In breast cancer patients with residual lesions after NAC, those with low Plakoglobin expression have relatively longer OS and Plakoglobin is an independent prognostic factor for OS.

[Overexpression of NAT10 induced platinum drugs resistance in breast cancer cell].

Objective: To observe the platinum drugs resistance effect of N-acetyltransferase 10 (NAT10) overexpression in breast cancer cell line and elucidate the underlining mechanisms. Methods: The experiment was divided into wild-type (MCF-7 wild-type cells without any treatment) group, NAT10 overexpression group (H-NAT10 plasmid transfected into MCF-7 cells) and NAT10 knockdown group (SH-NAT10 plasmid transfected into MCF-7 cells). The invasion was detected by Transwell array, the interaction between NAT10 and PARP1 was detected by co-immunoprecipitation. The impact of NAT10 overexpression or knockdown on the acetylation level of PARP1 and its half-life was also determined. Immunostaining and IP array were used to detect the recruitment of DNA damage repair protein by acetylated PARP1. Flow cytometry was used to detect the cell apoptosis. Results: Transwell invasion assay showed that the number of cell invasion was 483.00±46.90 in the NAT10 overexpression group, 469.00±40.50 in the NAT10 knockdown group, and 445.00±35.50 in the MCF-7 wild-type cells, and the differences were not statistically significant (P>0.05). In the presence of 10 µmol/L oxaliplatin, the number of cell invasion was 502.00±45.60 in the NAT10 overexpression group and 105.00±20.50 in the NAT10 knockdown group, both statistically significant (P<0.05) compared with 219.00±31.50 in wild-type cells. In the presence of 10 µmol/L oxaliplatin, NAT10 overexpression enhanced the binding of PARP1 to NAT10 compared with wild-type cells, whereas the use of the NAT10 inhibitor Remodelin inhibited the mutual binding of the two. Overexpression of NAT10 induced PARP1 acetylation followed by increased PARP1 binding to XRCC1, and knockdown of NAT10 expression reduced PARP1 binding to XRCC1. Overexpression of NAT10 enhanced PARP1 binding to LIG3, while knockdown of NAT10 expression decreased PARP1 binding to LIG3. In 10 µmol/L oxaliplatin-treated cells, the γH2AX expression level was 0.38±0.02 in NAT10 overexpressing cells and 1.36±0.15 in NAT10 knockdown cells, both statistically significant (P<0.05) compared with 1.00±0.00 in wild-type cells. In 10 µmol/L oxaliplatin treated cells, the apoptosis rate was (6.54±0.68)% in the NAT10 overexpression group and (12.98±2.54)% in the NAT10 knockdown group, both of which were statistically significant (P<0.05) compared with (9.67±0.37)% in wild-type cells. Conclusion: NAT10 overexpression enhances the binding of NAT10 to PARP1 and promotes the acetylation of PARP1, which in turn prolongs the half-life of PARP1, thus enhancing PARP1 recruitment of DNA damage repair related proteins to the damage sites, promoting DNA damage repair and ultimately the survival of breast cancer cells.

[A nomogram to predict non-sentinel lymph node metastasis for breast cancer patients with positive axillary sentinel lymph node].

Objective: To identify the risk factors of non-sentinel lymph node (nSLN) metastasis in breast cancer patients with 1~2 positive axillary sentinel lymph node (SLN) and construct an accurate prediction model. Methods: Retrospective chart review was performed in 917 breast cancer patients who underwent surgery treatment between 2002 and 2017 and pathologically confirmed 1-2 positive SLNs. According to the date of surgery, patients were divided into training group (497 cases) and validation group (420 cases). A nomogram was built to predict nSLN metastasis and the accuracy of the model was validated. Results: Among the 917 patients, 251 (27.4%) had nSLN metastasis. Univariate analysis showed tumor grade, lymphovascular invasion (LVI), extra-capsular extension (ECE), the number of positive and negative SLN and macro-metastasis of SLN were associated with nSLN metastasis (all P<0.05). Multivariate Logistic regression analysis showed the numbers of positive SLN, negative SLN and macro-metastasis of SLN were independent predictors of nSLN metastasis (all P<0.05). A nomogram was constructed based on the 6 factors. The area under the receiver operating characteristic curve was 0.718 for the training group and 0.742 for the validation group. Conclusion: We have developed a nomogram that uses 6 risk factors commonly available to accurately estimate the likelihood of nSLN metastasis for individual patient, which might be helpful for radiation oncologists to make a decision on regional nodal irradiation.