Overexpression of NAT10 induced platinum drugs resistance in breast cancer cell / 中华肿瘤杂志

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.

En bloc Resection for Right Colon Cancer Directly Invading Duodenum or Pancreatic Head

PURPOSE: We undertook this study to analyze clinical features and surgical outcome of en bloc resections of the right side colon cancer directly invading duodenum and/or pancreatic head. MATERIALS AND METHODS: The records of all patients who underwent en bloc resection of duodenum and/or pancreas for right colon cancers were analyzed retrospectively. From September 1994 to September 2006, 1,016 patients underwent curative right hemicolectomy. Nine patients (0.9%) had en bloc resection of a right side colon cancer with duodenum or pancreatic head invasion. RESULTS: The median operative time was 320 minutes (range, 200-420) and the median blood loss was 700 mL (range, 100-2,000). The mean size of tumor was 6.6 cm (range, 3.2-10.7). The mean preoperative carcinoembryonic antigen (CEA) was 10.6 ng/mL (range, 0.2-50.8). There was no 30 day perioperative mortality. The median disease-free survival was 23.5 months [95% confidence interval (CI) 5.2-41.8] and the median overall survival was 28.1 months (95% CI 9.7-46.5). CONCLUSIONS: In patients with locally advanced right side colon cancer that directly invades the duodenum or pancreas can be safely resected with curative potential with minimum morbidity and mortality. Long term disease free survival can occur in a significant number of patients undergoing curative en bloc resection in this particular subset of patients.

A Phase II Study of Cetuximab (Erbitux(R)) plus FOLFIRI for Irinotecan and Oxaliplatin-refractory Metastatic Colorectal Cancer

We have evaluated the efficacy and safety of cetuximab plus FOLFIRI for irinotecan and oxaliplatin-refractory colorectal cancers. From September 2004 to February 2006, 31 patients with metastatic colorectal cancer were treated with cetuximab (400 mg/m2 intravenously [IV] over 2 hr on day 1 followed by weekly 1-hr infusions of 250 mg/m2) plus bi-weekly FOLFIRI (irinotecan 150 mg/m2 IV over 90 min, and leucovorin 100 mg/m2 IV over 2 hr, followed by 5-FU 400 mg/m2 IV bolus on day 1, and followed by 5-FU 2,400 mg/m2 by continuous IV over 46 hrs). Patients received a median of four cycles (range: 1-23). Eight (25.8%) patients had confirmed partial responses and 10 (32.2%) had stable disease. After a median follow-up of 13.2 months for surviving patients, the median time to progression was 2.9 months, the median duration of response was 5.4 months, and the median overall survival was 10.9 months. Skin toxicity was observed in 25 patients (80.4%) including grade 3 in 6 patients (19.4%). Other common non-hematologic toxicities of all grades were mucositis (32.3%), asthenia (22.6%), diarrhea (12.9%), and paronychial cracking (12.9%). The combination of cetuximab with FOLFIRI was effective and tolerable in colorectal cancer patients heavily pretreated with a number of chemotherapy regimens.

Irinotecan and oxaliplatin: an overview of the novel chemotherapeutic options for the treatment of advanced colorectal cancer

Colorectal cancer is one of the most frequent malignancies in humans and an important cause of cancer death. Metastatic colorectal cancer remains incurable with available systemic therapeutic options. The most active cytotoxic drug against this malignancy, the antimetabolite 5-fluorouracil, was developed more than forty years ago, and as a single agent produces responses in only 10 to 15 percent of patients which in general last less than one year. Efforts to ameliorate these poor results resulted in the 5-fluorouracil/leucovorin combination, which enhances response rates about two-fold, without, however, significantly improving survival rates. The recent emergence of a handful of new 5-fluorouracil analogues and folate antagonists, as well as the topoisomerase I inhibitor irinotecan, and the third-generation platinum compound oxaliplatin, is likely to alter this gloomy scenario. These agents are at least as effective as 5-fluorouracil in patients with advanced colorectal carcinoma, both untreated and previously treated with 5-fluorouracil-based regimens. This has led to the approval of irinotecan as second-line treatment for 5-fluorouracil-refractory disease, while the use of oxaliplatin has been suggested for patients having a defective 5-fluorouracil catabolism. Recently, FDA approved the combination of irinotecan with 5-fluorouracil and leucovorin for first-line treatment of advanced colon cancer. Based on the synergistic preclinical antitumor effects of some of these agents, their meaningful single-agent activity, distinct mechanisms of cytotoxicity and resistance, and only partially overlapping toxicity profiles, effective combination regimens are now being developed, which are likely to lead to a new, more hopeful era for patients suffering from advanced colorectal carcinoma

Antitumor activity of five new platinum complexes having a glycolate leaving ligand

In an attempt to develop a new anticancer platinum complex with greater or equivalent antitumor activity but reduced side effects compared with cisplatin (CDDP), a series of new platinum complexes having a glycolate leaving ligand was synthesized. Among them, five complexes were selected for further development on the basis of adequate water solubility, low nephrotoxicity and high antitumor activity in a murine system. The chemosensitivity of these five complexes was examined in MTT assay against two human pulmonary adenocarcinoma cell lines, PC-9 and PC-14, and two human stomach adenocarcinoma cell lines, MKN-45 and KATO III. Their IC50 and relative antitumor activity (RAA) values were compared with those of CDDP and 254-S, a second-generation platinum complex with a glycolate leaving ligand under phase III clinical trial. The lowest mean IC50 value was observed in CDDP, followed by SKI 2034R and SKI 2033R. In this study, the antitumor activity was evaluated in terms of RAA values and SKI 2034R showed the highest RAA value. The order of RAA values was SKI 2034R > CDDP > SKI 2032R > SKI 2033R > SKI 2030R > SKI 2029R > 254-S. Based on the RAA order, we have recommended SKI 2034R as the most promising candidate for further development of a clinically useful platinum complex.