Colonic Lysine Homocysteinylation Induced by High-Fat Diet Suppresses DNA Damage Repair.

Colorectal cancer (CRC) onset is profoundly affected by Western diet. Here, we report that high-fat (HF) diet-induced, organ-specific colonic lysine homocysteinylation (K-Hcy) increase might promote CRC onset by impeding DNA damage repair. HF chow induced elevated methionyl-tRNA synthetase (MARS) expression and K-Hcy levels and DNA damage accumulation in the mouse and rat colon, resulting in a phenotype identical to that of CRC tissues. Moreover, the increased copy number of MARS, whose protein product promotes K-Hcy, correlated with increased CRC risk in humans. Mechanistically, MARS preferentially bound to and modified ataxia-telangiectasia and Rad3-related protein (ATR), inhibited ATR and its downstream effectors checkpoint kinase-1 and p53, and relieved cell-cycle arrest and decreased DNA damage-induced apoptosis by disrupting the binding of ATR-interacting protein to ATR. Inhibiting K-Hcy by targeting MARS reversed these effects and suppressed oncogenic CRC cell growth. Our study reveals a mechanism of Western-diet-associated CRC and highlights an intervention approach for reversing diet-induced oncogenic effects.

Prognostic Value of Lymph Node Ratio in Locally Advanced Rectal Cancer Patients After Preoperative Chemoradiotherapy Followed by Total Mesorectal Excision.

Although the absolute number of positive lymph nodes (LNs) has been established as 1 of the most important prognostic factors in rectal cancers, many researchers have proposed that the lymph node ratio (LNR) may have better predicted outcomes. We conducted a retrospective study to compare the predictive ability of LNR and ypN category in rectal cancer. A total of 264 locally advanced rectal cancer (LARC) patients who underwent preoperative chemoradiotherapy (CRT) followed by total mesorectal excision (TME) between 2005 and 2012 were reviewed. All patients were categorized into 3 groups or patients with metastatic LNs were categorized into 2 groups according to the LNR. The prognostic effect on overall survival (OS) and disease-free survival (DFS) was evaluated. With a median follow-up of 45 months, the OS and DFS were 68.4% and 59.3% for the entire cohort, respectively. The respective 5-year OS and DFS rates for the 3 groups (LNR = 0, 0 < LNR ≤ 0.20, and 0.20 < LNR ≤ 1.0) were as follows: 83.2%, 72.6%, and 49.4% (P < 0.001) and 79.5%, 57.3%, and 33.5% (P < 0.001), respectively. Multivariate analysis revealed that LNR and differentiation, but not the number of positive LNs, had independent prognostic value for OS (hazard ratio [HR] = 2.328, 95% confidence interval [CI]: 1.850-4.526, P < 0.001) and DFS (HR = 3.004, 95% CI: 1.616-5.980, P < 0.001). As for patients with positive LNs, the respective 5-year OS and DFS rates for the 2 groups (0 < LNR ≤ 0.20, and 0.20 < LNR ≤ 1.0) were 72.6% and 49.4% (P < 0.001) and 57.3% and 33.5% (P < 0.001), respectively. Multivariate analysis revealed that only LNR was an independent factor for OS (HR = 3.214, 95% CI: 1.726-5.986, P < 0.001) and DFS (HR = 4.230, 95% CI: 1.825-6.458, P < 0.001). Subgroups analysis demonstrated that the ypN category had no impact on survival whereas increased LNR was a significantly prognostic indicator for worse survival in the LNs < 12 subgroup. LNR is an independent prognostic factor in LARC patients treated with preoperative CRT followed by TME. It may be a better independent staging method than the number of metastatic LNs when <12 LNs are harvested after preoperative CRT.

[Association of epithermal growth factor receptor expression and its downstream gene mutation status with radiosensitivity of colorectal carcinoma cell lines in vitro].

OBJECTIVE: To investigate the effect of epithermal growth factor receptor (EGFR) expression and K-ras, B-raf and PIK3CA mutation status on the radiosensitivity of human colorectal carcinoma (CRC) cell lines in vitro. METHODS: Real-time RT-PCR was used to measure EGFR mRNA expression in nine human CRC cell lines, and K-ras, B-raf and PIK3CA mutation status of each CRC cell line was also identified respectively. After treatment with irradiation at graded dose, the cell viability was measured by clonogenic survival assay. The rate of cell apoptosis and cell cycle distribution were tested by flow cytometry. The cell morphology was observed with hoechst 33258 staining to analyze the correlation between EGFR mRNA expression and radiosensitivity of CRC cell lines. RESULTS: A positive correlation between EGFR mRNA expression and survival fraction of 2 Gy(SF2) was observed (r=0.717, P=0.030). Association was also identified between the mutation status of PIK3CA and radiosensitivity (t=2.401, P=0.047), while mutation status of K-ras and B-raf was not associated with radiosensitivity. At 48-hour after exposing to irradiation, the apoptosis rate of radiosensitive cell line (HCT116) was significantly increased in a dose-dependent manner (P<0.05), while the apoptosis rate of radioresistant cell line (HT29) was significantly increased only when radiation dose increased to 6 Gy. The ratio of G0/G1 phase was reduced significantly with the increase of radiation dose in radiosensitive cell line (HCT116, P<0.05), while this trend was not observed in radioresistant cell line (HT29, P>0.05). CONCLUSIONS: Over-expression of EGFR mRNA is correlated to radioresistance of human CRC cell lines, and mutation status of PIK3CA is closely related with radiosensitivity of CRC cells. The inhibition of apoptosis and G0/G1 arrest may induce the radioresistance of CRC cell lines.

Expression of ZNF148 in different developing stages of colorectal cancer and its prognostic value: a large Chinese study based on tissue microarray.

BACKGROUND: It has been speculated that zinc finger protein 148 (ZNF148) is a tumor suppressor. However, to the authors' knowledge, little is known about the clinical significance of ZNF148 expression in patients with colorectal cancer (CRC). The objective of the current study was to clarify the association between ZNF148 expression and the postoperative prognosis of patients with CRC. METHODS: Tissue microarrays containing 56 normal mucosa, 51 adenoma, 742 CRC (TNM stage I-IV), 16 familial adenomatous polyposis, and 21 metastatic CRC specimens were examined immunohistochemically for ZNF148 expression. RESULTS: Expression of ZNF148 was found to increase consecutively from normal mucosa to stage I CRC, and then decreased consecutively from stage I to stage IV CRC. Lower expression of ZNF148 in tumors was found to be significantly associated with lymph node metastases, advanced TNM disease stage, poor differentiation, higher rate of disease recurrence, worse overall survival (OS), and shorter disease-free survival. High expression of ZNF148 was also associated with improved OS (P = .025) and disease-free survival (P = .042) in patients with stages II to III CRC. On multivariate Cox analysis, lower ZNF148 expression in tumors, advanced TNM stage, colon cancer, and elevated serum carbohydrate antigen 19-9 (CA19-9) were found to be significant factors for a worse OS. In 16 patients with familial adenomatous polyposis, ZNF148 expression was upregulated at steps toward carcinogenesis. In 21 patients with metastatic CRC, although ZNF148 expression was higher in primary tumors compared with adjacent mucosa, its expression in metastatic tumors was significantly lower than that in primary tumors. CONCLUSIONS: Although ZNF148 expression is related to colorectal carcinogenesis, high ZNF148 expression in patients with CRC appears to be inversely associated with malignant phenotypes and may serve as a significant prognostic factor after surgery for patients with CRC.

[Impacts of preoperative radiochemotherapy on operation and postoperative complications in patients with mid-low rectal carcinomas].

OBJECTIVE: To investigate the impact of preoperative radiochemotherapy on postoperative complications in patients with mid-low rectal carcinomas. METHODS: Clinicopathologic data of T3 and T4 patients with mid-low rectal carcinomas in the Department of Colorectal Surgery at the Changhai Hospital of The Second Military Medical University from January 2009 to December 2010 were analyzed retrospectively. This cohort included 81 patients treated with preoperative radiochemotherapy followed by operation(radiochemotherapy group) and 93 cases who underwent surgery alone(control group). RESULTS: Both resection rate and sphincter preservation rate were higher in the radiochemotherapy group(100% and 86.4%) than those in the control group(94.6% and 73.1%), and the difference in sphincter preservation rate was statistically significant(P=0.039). There were no significant differences in the mean operative time [(130±15) min vs.(125±20) min, P>0.05] and mean amount of bleeding [(100±15) ml vs. (95±10) ml, P>0.05] between the two groups. The overall incidence of postoperative complications was similar(9.9% vs. 9.7%, P>0.05). CONCLUSIONS: Preoperative radiochemotherapy can significantly increase sphincter preservation rate of mid-low rectal carcinomas, and does not increase the difficulty in surgical procedure and postoperative complications.

[Laparoscopic total mesorectal excision combined with intersphincteric resection for ultra-low rectal cancer].

OBJECTIVE: To evaluate clinical outcomes after laparoscopic total mesorectal excision (TME) combined with intersphincteric resection (ISR) for ultra-low rectal tumors. METHODS: Clinical data of 36 patients with ultra-low rectal tumor undergoing laparoscopic TME combined with ISR were analyzed retrospectively. RESULTS: The median distance from the inferior margin of the tumor to the anal verge was 3.4 (2.0-5.0) cm. There were 33 cases of well/moderately differentiated adenocarcinoma and 3 rectal malignant villous adenoma. There were 16 patients with stage I disease, 15 with stage II A, 3 with stage III A, and 1 with III B. Postoperatively, one patient developed stenosis at the end ileostomy and 3 anastomotic leakage. After a median follow-up of 16(4-49) months, one patient developed local recurrence at the anastomosis and one case died of liver metastasis. In the 19 patients who had a minimum follow-up of one year, the bowel movements frequency ranged from 1-4 times per day, and these patients were able to withhold defecation for more than 5 minutes. CONCLUSIONS: Laparoscopic TME combined with ISR can achieve oncologic clearance, sphincter preservation, and minimal invasiveness for ultra-lower rectal cancer. However, patients selection should be cautious.

[Value of protective stoma in intersphincteric resection for ultra-low rectal cancer].

OBJECTIVE: To investigate the value of protective stoma in intersphincteric resection (ISR) for ultra-low rectal cancer. METHODS: Clinical data of 56 ultra-low rectal cancer patients without involvement of external anal sphincter treated during January 1999 to July 2009 with trans-anal ISR plus trans-abdominal total mesorectum excision and coloanal anastomosis were retrospectively analyzed. The patients were divided into two groups based on whether they received protective ostomy: ostomy group (16 cases) and ostomy-free group (40 cases). The postoperative complications as well as anal functional restoration were compared between the two groups. RESULTS: Sixteen cases (32.1%) of the 56 patients received protective stoma. The complication rate of anastomosis and anus complication rate in the ostomy-free group were significantly higher than those in ostomy group [35.0% (14/40) and 40.0% (16/40) vs. 1/16 and 1/16; P < 0.05]. In the ostomy-free group, one patient developed anastomotic dehiscence and tumor recurrence, the patients was given permanent colostomy, and the other three patients with lesions in the anastomosis and anus received ostomy and secondary surgical treatment, with a reoperation rate of 10.0% (4/40). The anal function of patients in the two groups were both decreased after the operation. The rate of patients got Kirwan grade I anal sphincter function in the 3rd, 6th and 12th month after protective stoma operation was 11/16, 13/15 and 11/13 in the ostomy group, respectively; and those were 30.0%, 37.5% and 45.0% in the ostomy-free group, respectively. Anal function was significantly better in the ostomy group than that in the ostomy-free group during the same postoperative period (P < 0.05). CONCLUSION: Protective stoma can avoid anastomotic leakage following ISR for ultra-low rectal cancer, and alleviate the suffering of anal incontinence in the early postoperative period, and is conducive to the restoration of anal function.

[Application of Altemeier procedure in the emergent management of acute incarcerated rectal prolapse].

OBJECTIVE: To evaluate the perineal rectosigmoidectomy(Altemeier procedure) in the emergent management of acute incarcerated rectal prolapse. METHODS: Clinical and follow-up data of 9 patients with acute incarcerated rectal prolapse undergone Altemeier procedure were retrospectively analyzed. RESULTS: The mean operation time was 1.7 (range 1.0-1.5) hours. The mean total blood loss during surgery was 109 (50-200) ml. The mean time to the first bowel movements was 2.8(1-6) days after surgery. The hospital stay was 5.3(3-10) days. There were no postoperative complications such as anastomotic leakage, intra-abdominal infection, or urogenital dysfunction. One patient developed thrombosis in the mesorectum and one patient had symptoms of anal discomfort. After a mean follow-up of 3.5(5 months-6.5 years) years, no patient had recurrent prolapse. Six months after operation, anal function was Kirwan grade I( in 8 cases and grade II( in 1 case. All the patients were satisfied with the result. CONCLUSION: Altemeier procedure can result in good postoperative anal function when treating incarcerated rectal prolapse, which should be the first choice in emergency treatment.

[Combination of trans-anal intersphincteric resection and trans-abdominal total mesorectal excision for anus-retained ultra-low rectal tumors].

OBJECTIVE: To study the combination of trans-anal intersphincteric resection and transabdominal total mesorectal excision for anus-retained ultra-low rectal tumors. METHODS: Clinical data of 34 ultra-low rectal tumor patients without external anal sphincter involved, who underwent the combination surgery, were retrospectively analyzed. RESULTS: The distance from the distal incisal margin of the rectum to the inferior margin of the tumor ranged from 1.8 cm to 3.0 cm on an average of 2.1 cm. For pathological types, there were 23 cases of adenocarcinoma (9 well differentiated and 14 moderately differentiated), 1 papillary carcinoma, 2 rectal stromal tumor, 5 rectal villous adenoma with neoplasia and 3 giant villous adenoma. For pathological stages, there were 18 cases at stage pTNM I, 5 at IIA, 1 at IIB, 4 at IIIA, 1 at III and for T grading, there were 15 cases at stage T1, 5 at T2, 8 at T3, 1 at T4. In these 34 patients, there were 3 cases with postoperative anastomotic stenosis, 2 with postoperative anastomotic rupture, 2 with rectovaginal fistula and no operative death. Because of the dysfunction of bowel control, bowel frequency varied from 3 to 12 in the early stage after operation, but with the recovery of anus function, bowel frequency decreased and ranged form 1 to 5 times a day and the time of formed bowel control could be more than 5 min in 6-12 months after operation. However, patients underwent total resection of internal anal sphincter still suffered from incontinence of loose stool after 1 year. After operation, anastomotic recurrence was found in 1 case in 5 months, liver metastasis in 1 case in 10 months and 28 months respectively, cardiac sudden death in 1 case in 26 months. CONCLUSION: The combination of trans-anal ISR and trans-abdominal TME for anus-retained ultra low rectal tumor is not only coincident with radical tumor principle but also retains the function of anus, on the premise of the strict indication.

[Clinical application of intersphincteric resection in the anal-preserving operation for ultra-low rectal carcinoma].

OBJECTIVE: To investigate the clinical application of intersphincter resection (ISR) combined with total mesorectal excision (TME) and colon-anal anastomosis in the treatment for ultra-low rectal carcinoma. METHODS: To review and analyze retrospectively the data of 34 patients with ultra-low rectal carcinoma (without external anal sphincter involvement) who received treatment of ISR, TME and colon-anal anastomosis. RESULTS: Partial resection of internal sphincter was performed in the patients with a distal edge of the tumor greater than or equal to 2 cm from the dentate line. Subtotal removal of the rectum was performed between 1 cm and 2 cm. Total resection was performed in less than 1 cm or involvement of dentate line. Reconstruction of digestive tract was done by manual colon-anal anastomosis. The average distance from distal excised margin to the tumor was 2.3 (1.8 - 3.2) cm among 34 patients. The pathological types were as follows: 28 cases of adenocarcinoma (11 were well differentiated, 17 moderately differentiated), 1 case of papillary carcinoma and 5 cases of villous adenoma with malignant change. The postoperative pathological stages were: Dukes stage A in 28 cases, stage B in 1 and stage C in 5 cases. The pTNM staging was 28 cases in phase I, 1 in phase IIa, 4 in phase IIIa and 1 in phase IIIb. The T stages of the patients were as following: 16 Tl, 17 T2 and 1 T3. Postoperative anastomotic stenosis occurred in 3 cases, anastomotic dehiscence in 2 cases and rectovaginal fistula in 2 cases. The ability of controlling feces of patients decreased significantly in the early postoperative period, and restored gradually at 6 to 12 months after operation. Anastomotic recurrence occurred in 1 case at 5 months after operation and liver metastasis in 1 case at 40 months. CONCLUSION: With strictly grasping indications, radical resection can be attained and anal sphincter preserved by ISR combined with TME and colon-anal anastomosis. It is an effective sphincter-preserving operation.