Yoshihiko Fujinaka

ATR–Chk1 signaling pathway and homologous recombinational repair protect cells from 5-fluorouracil cytotoxicity

5-Fluorouracil (5-FU) has long been a mainstay antimetabolite chemotherapeutic drug for the treatment of major solid tumors, particularly colorectal cancer. 5-FU is processed intracellularly to yield active metabolites that compromise RNA and DNA metabolism. However, the mechanisms responsible for its cytotoxicity are not fully understood. From the phenotypic analysis of mutant chicken B lymphoma DT40 cells, we found that homologous recombinational repair (HRR), involving Rad54 and BRCA2, and the ATR-Chk1 signaling pathway, involving Rad9 and Rad17, significantly contribute to 5-FU tolerance. 5-FU induced γH2AX nuclear foci, which were colocalized with the key HRR factor Rad51, but not with DNA double-strand breaks (DSBs), in a dose-dependent manner as cells accumulated in the S phase. Inhibition of Chk1 kinase by UCN-01 increased 5-FU-induced γH2AX and enhanced 5-FU cytotoxicity not only in wild-type cells but also in Rad54- or BRCA2-deficient cells, suggesting that HRR and Chk1 kinase have non-overlapping roles in 5-FU tolerance. 5-FU-induced Chk1 phosphorylation was significantly impaired in Rad9- or Rad17-deficient cells, and severe γH2AX nuclear foci and DSBs were formed, which was followed by apoptosis. Finally, inhibition of Chk1 kinase by UCN-01 increased 5-FU-induced γH2AX nuclear foci and enhanced 5-FU cytotoxicity in Rad9- or Rad17-deficient cells. These results suggest that Rad9- and Rad17-independent activation of the ATR-Chk1 signaling pathway also significantly contributes to 5-FU tolerance.

The short term feasibility of abdominoperineal resection with prostatectomy for locally advanced rectal cancer: open and laparoscopic cases report

Total pelvic exenteration is often selected for advanced rectal cancer with prostatic invasion. The aim of this study was to evaluate the short term feasibility of the abdominoperineal resection with prostatectomy for locally advanced rectal cancer. We performed abdominoperineal resection with prostatectomy for 3 patients with locally advanced rectal cancer, including 2 patients by totally laparoscopic procedure. Patients’ background, intra- and postoperative factors and short-term prognosis were evaluated. All patients underwent complete resection of primary tumor with negative surgical margins. We could perform the surgery by both open and laparoscopic procedure in collaboration with urologist. There was no operation related mortality. One patient who was treated by open procedure had urinary anastomotic leakage. No patient had recurrenced, but one patient died of other disease. Our experience suggests that open or laparoscopic abdominoperineal resection with prostatectomy could be an alternative to total pelvic exenteration for the patients with rectal cancer invading the prostate. The collaboration with the urologist would be important to perform quality-controlled surgery.

Definitive Chemoradiotherapy and Salvage Esophagectomy for Esophageal Cancer Associated With Multiple Lung Metastases: A Case Report

The prognosis of esophageal cancer with distant metastasis is dismal. We report a 70-year-old man with esophageal cancer and multiple lung and lymph node metastases. Complete response was achieved following definitive chemoradiotherapy. Twenty-four months after the initial chemoradiotherapy, local recurrence was detected but there was no evidence of distant metastasis. Therefore, the patient underwent salvage esophagectomy. The surgery was well tolerated without any postoperative complications. The patient is still alive 48 months after the salvage surgery. Our experience suggests that salvage esophagectomy is an important component of multimodal therapy for the recurrence of esophageal cancer.

Successful surgical management for duodenum obstruction in a 66 year-old woman previously undiagnosed intestinal malrotation.

Intestinal malrotation is a congenital abnormality and is rarely seen in the adulthood. Most adult cases would be classified to the non-rotation type with Ladds band and Ladd procedure is the treatment of choice. A 66 year-old woman admitted to our hospital due to duodenum obstruction. Several tests revealed that she had intestinal malrotation previously undiagnosed. Operative findings showed the fusion of duodenum with jejunum by the incomplete Treitz ligament. There was no Ladds band and the right colon was unfixed. Dissection of the fusion completely released her symptom and she discharged without any complication. This is the first report of untypically intestinal malrotation in the adulthood without Ladds band.

Significance of FANCJ expression as a predictive marker of sensitivity to 5-fluorouracil in colorectal cancer.

10618 Background: Fanconi anemia protein, FANCJ, directly interacts with MLH1, a key protein involved in the DNA mismatch repair process. Deficient mismatch repair, or microsatellite instability, is a marker for the ineffectiveness of 5-fluorouracil (5-FU) and positive prognosis of colorectal cancer (CRC). We investigated the significance of FANCJ expression in CRC, focusing on the effects of 5-FU-based adjuvant chemotherapy. METHODS Clinicopathologic features and immunohistochemical expression of FANCJ and MLH1 were studied in 219 patients with CRC. We also analyzed 5-FU sensitivity in CRC cell lines with varying levels of FANCJ expression. RESULTS FANCJ expression was elevated in tumor tissues compared with normal epithelial tissue (p<0.001). High expression of FANCJ was significantly associated with 5-FU resistance measured by the succinate dehydrogenase inhibition test (p=0.02) and poor recurrence-free survival (RFS) (p=0.03). Among patients with stage II/III tumors who received 5-FU, patients with tumors exhibiting high FANCJ expression had significantly worse RFS than patients with tumors exhibiting low FANCJ expression (p=0.01). Among patients who did not receive adjuvant chemotherapy, FANCJ expression was not correlated with RFS (p=0.76). High FANCJ expression was correlated with 5-FU resistance in tumors with normal MLH1 expression (p=0.01), but not in tumors not expressing MLH1 (p=0.67). In vitro, FANCJ overexpression was correlated with 5-FU resistance in MLH1-proficient HCT116 3-6 cells, but not in MLH1-deficient HCT116 cells. CONCLUSIONS FANCJ could be a useful biomarker to predict the response to 5-FU and prognosis of CRC, particularly in tumors with normal MLH1 expression.