Search

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths in Japan. The etiology of CRC has been linked to numerous factors including genetic mutation, diet, life style, inflammation, and recently, the gut microbiota. However, CRC-associated gut microbiota is still largely unexamined. This study used terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing (NGS) to analyze and compare gut microbiota of Japanese control subjects and Japanese patients with carcinoma in adenoma. Stool samples were collected from 49 control subjects, 50 patients with colon adenoma, and 9 patients with colorectal cancer (3/9 with invasive cancer and 6/9 with carcinoma in adenoma) immediately before colonoscopy; DNA was extracted from each stool sample. Based on T-RFLP analysis, 12 subjects (six control and six carcinoma in adenoma subjects) were selected; their samples were used for NGS and species-level analysis. T-RFLP analysis showed no significant differences in bacterial population between control, adenoma and cancer groups. However, NGS revealed that i), control and carcinoma in adenoma subjects had different gut microbiota compositions, ii), one bacterial genus (Slackia) was significantly associated with the control group and four bacterial genera (Actinomyces, Atopobium, Fusobacterium, and Haemophilus) were significantly associated with the carcinoma-in-adenoma group, and iii), several bacterial species were significantly associated with each type (control: Eubacterium coprostanoligens; carcinoma in adenoma: Actinomyces odontolyticus, Bacteroides fragiles, Clostridium nexile, Fusobacterium varium, Haemophilus parainfluenzae, Prevotella stercorea, Streptococcus gordonii, and Veillonella dispar). Gut microbial properties differ between control subjects and carcinoma-in-adenoma patients in this Japanese population, suggesting that gut microbiota is related to CRC prevention and development.

Toll-like receptors (TLRs) are pattern-recognition receptors that are important in immune signaling. TLR recognition of various viral components including double-stranded RNA (TLR3) and unmethylated CpG-DNA (TLR9) plays a crucial role in cell survival. However, TLR expression and function in colon carcinoma cells are not well clarified. We investigated the expression of TLR3 and TLR9 in colon carcinoma cells using immunohistochemical methods. The function of TLR3 and TLR9 signaling in carcinoma cell lines was studied by direct cell stimulation with, or by cell transfection of, polyinosinic-polycytidylic acid (Poly I:C), a synthetic form of dsRNA, and by cell stimulation with CpG-oligodeoxynucleotides (ODNs), respectively. Positive TLR3 and TLR9 immunohistochemical staining was observed in 91 and 86% of human hepatocellular carcinoma (HCC) tissues, respectively. Cell surface stimulation of TLR3 with Poly I:C did not affect cell viability but it did activate NF-κB activity. By contrast, stimulation of intracellular TLRs with transfected Poly I:C significantly induced apoptosis. Cell surface stimulation of TLR9 with CpG-ODNs promoted cell proliferation, and, furthermore, these CpG-ODN TLR9 agonists reduced the cytotoxicity of the anticancer drug adriamycin. Cell surface expression of TLR3 and TLR9 in colon carcinoma cells plays an important role in cell survival. In addition, the proapoptotic activity of intracellularly expressed TLR3 may provide the possibility of using TLR3 agonists as novel clinical cytotoxic agents against colon carcinoma cells.

The inhibitors of apoptosis (IAPs) family regulate apoptosis by preventing the action of the central execution phase, and function as mediators and regulators of the anti-apoptotic activity of the v-Rel and NF-kappaB transcription factor families. The targeting of IAPs may be a promising strategy, but it is not well elucidated in human hepatocellular carcinomas (HCCs). We have therefore investigated the effects of the down-regulation of IAPs (XIAP or survivin) on the TNF-related apoptosis-inducing ligand (TRAIL) and chemotherapeutic agents that induced apoptosis in human HCC cells. To inhibit the IAPs gene expression, we designed small interfering RNA (siRNA) against the X-chromosome-linked IAP (XIAP) or survivin and investigated their efficacy in the suppression of the XIAP or survivin expression in two HCC cells (SK-Hep1 and HLE), and their consequent antitumor potential. We found that the designed siRNAs against the XIAP and survivin downregulated the protein expression of respective genes by almost 50%. The suppression of IAPs resulted in a significant decrease in procaspase-3 levels, especially by suppression of the XIAP. The apoptosis cell count was small in cells transfected with control siRNA and siRNA against the XIAP or survivin, but after treatment with 10 ng/ml of TRAIL, the apoptosis cells increased 2-3 times by the suppression of IAPs as control. The cytotoxicity of doxorubicin and camptothecin was augmented by the suppression of the XIAP in SK-Hep1 cells, whereas the suppression of survivin did not affect cytotoxicity. In conclusion, downregulation of the XIAP or survivin enhances cell death by TRAIL and increases sensitivity against some chemotherapeutic agents in HCC cells. In particular, the XIAP may be a potential target to increase therapeutic sensitivity.

The TNF-receptor family has a dual signaling pathway, including induction of apoptosis and NF-kappaB activation associated with cell survival. Hepatocellular carcinoma (HCC) cells express TNF-receptor family members and the signaling from these receptors induces NF-kappaB activation. However, the role of Fas in induction of NF-kappaB activation in HCC cells is not well understood. In this study, SK-Hep1, HepG2 or HLE cells were stimulated by anti-Fas agonistic antibody. Fas stimulation induced NF-kappaB activation in a dose-dependent manner in SK-Hep1 and HepG2 cell lines, but not in HLE cells. Anti-Fas agonistic antibody or the metabolic inhibitor, cyclo-heximide (CHX), failed to kill SK-Hep1 cells, but co-incubation with anti-Fas agonistic antibody and CHX was effective for induction of apoptosis. SK-Hep1 cell lines receiving Fas stimulation had increased viability, but the extent of cell proliferation was not dose-dependent. The observation suggests that Fas stimulation may contribute to HCC cell survival or proliferation.

The TNF-receptor family has a dual signaling pathway, including induction of apoptosis and NF-kappaB activation associated with cell survival. Hepatocellular carcinoma (HCC) cells express TNF-receptor family members and the signaling from these receptors induces NF-kappaB activation. However, the role of Fas in induction of NF-kappaB activation in HCC cells is not well understood. In this study, SK-Hep1, HepG2 or HLE cells were stimulated by anti-Fas agonistic antibody. Fas stimulation induced NF-kappaB activation in a dose-dependent manner in SK-Hep1 and HepG2 cell lines, but not in HLE cells. Anti-Fas agonistic antibody or the metabolic inhibitor, cyclo-heximide (CHX), failed to kill SK-Hep1 cells, but co-incubation with anti-Fas agonistic antibody and CHX was effective for induction of apoptosis. SK-Hep1 cell lines receiving Fas stimulation had increased viability, but the extent of cell proliferation was not dose-dependent. The observation suggests that Fas stimulation may contribute to HCC cell survival or proliferation.

Six patients with small size (< or =2.0 cm in diameter) hepatocellular carcinoma (HCC) on their liver surface underwent laparoscopic microwave coagulation therapy (LMCT) in our institute. All cases showed complete necrosis after LMCT alone and there were no major complications during the LMCT. During the follow-up period, one patient had recurrent HCC at the LMCT-treated lesion site and two patients had lesions at sites distant to the LMCT-treated site. Two out of these three patients had presented with severe liver dysfunction at admission and died within the follow-up period. LMCT is believed to be a useful and safe treatment for small size HCC on the liver surface, and treatment can achieve complete tumor necrosis. However, in severe liver dysfunction, the use of LMCT may have a negative influence on patient survival.

Digital subtraction imaging was compared to helical CT, DSA, and US angiography to assess its usefulness in the evaluation of vascularity in hepatocellular carcinoma (HCC). Digital subtraction imaging using Levovist as the contrast agent was performed in 41 patients with 43 nodules (22 men and 19 women, aged 50 to 83 years; mean age, 65 years; mean maximum tumor diameter, 27.8+/-17.1 mm). Digital subtraction imaging showed hypervascular enhancement in 39 of the 43 nodules (91%). Helical CT showed areas of high attenuation in 40 of the 43 nodules (93%), while DSA and US angiography showed positive enhancement in 38 and 43 of the 43 nodules (88% and 100%), respectively. Digital subtraction imaging is useful for evaluating vascularity in HCC when the tumor can be visualized with non-enhanced US angiography.

Cavernous hepatic hemangiomas are benign liver tumors and present as incidental findings on sonographic examinations, but little is known concerning their natural course. Therefore, we performed a clinical and imaging follow-up of 64 cases of cavernous hepatic hemangioma in 50 patients during an average 18.8 month period. One case presented a symptom of slightly right upper quadrant pain and two cases showed thrombocytopenia. In one of the thrombocytopenia cases, cavernous hepatic hemangioma was resected because of Kasabach-Merrit syndrome. No case increased in size during follow-up, but one case decreased and disappeared. These results suggested that prolonged clinical and imaging follow-up of cavernous hepatic hemangiomas may be needed.