Studies on mechanism of Sialy Lewis-X antigen in liver metastases of human colorectal carcinoma

Transfer of metastatic traits via miR-200c in extracellular vesicles derived from colorectal cancer stem cells is inhibited by atractylenolide I

Cancer stem cells (CSCs) are important factors contributing to tumorigenesis. We examined whether CSCs isolated from colorectal cancer (CRC) cells possess metastatic properties that can be transferred to non-CSCs via the delivery of miR-200c enclosed in extracellular vesicles (EVs). The inhibitory effect of atractylenolide I (ATL-1), a traditional Chinese medicinal compound, on miR-200c activity and metastatic transfer was investigated. EVs were isolated from colorectal CSCs. The expression of miR-200c was evaluated in CSCs and CSC-derived EVs, and horizontal transfer of metastatic properties via EVs to non-CSCs was investigated in terms of cell behavior and phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling. CSCs isolated from metastatic CRC cells exhibited higher levels of miR-200c than those in nonmetastatic CRC cells. Overexpression of miR-200c in CSCs enhanced metastatic potential by promoting proliferation and inhibiting apoptosis, in turn leading to the release of EVs carrying an excess of miR-200c. Non-CSCs co-cultured with miR-200c-containing EVs exhibited enhanced invasion and stemness maintenance associated with PI3K/Akt/mTOR activation, demonstrating successful metastatic transfer via EV delivery. Furthermore, ATL-1 impaired the EV-mediated transfer of metastatic properties by suppressing miR-200c activity and disrupting EV uptake by non-CSCs. EVs are critical signal transducers that facilitate intercellular communication and exchange of metastatic properties, which can be controlled by ATL-1. The findings are useful in the development of microRNA-based anticancer strategies by targeting EV-mediated activity, especially using natural compounds.

Systematic high-content proteomic analysis reveals substantial immunologic changes in colorectal cancer

The immune system is a significant determinant of epithelial tumorigenesis, but its role in colorectal cancer pathogenesis is not well understood. The function of the immune system depends upon the integrity of the protein network environment, and thus, we performed MELC immunofluorescence microscopy focusing on the lamina propria. By analyzing structurally intact tissues from colorectal cancer, ulcerative colitis, and healthy colonic mucosa, we used this unique and novel highly multiplexed robotic-imaging technology, which allows visualizing dozens of proteins simultaneously, and explored the toponome in colorectal cancer mucosa for the first time. We identified 1,930 motifs that distinguish control from colorectal cancer tissue. In colorectal cancer, the number of activated T cells is increased, explained by a lack of bax, caspase-3, and caspase-8. Whereas CD4(+)CD25(+) T cells are decreased and are, other than in ulcerative colitis, not activated, cytotoxic T cells are significantly increased in colorectal cancer. Furthermore, the number of activated human lymphocyte antigen (HLA)-DR(+) T-cells is increased in colorectal cancer, pointing to an altered antigen presentation. In colorectal cancer, CD3(+)CD29(+) expression and assembly of the LFA-1 and LFA-3 receptor are differentially changed, indicating a distinct regulation of T-cell adhesion in colorectal cancer. We also identified increased numbers of natural killer and CD44(+) cells in the colorectal cancer mucosa and nuclear factor-kappaB as regulator of apoptosis in these cell populations. High-content proteomic analysis showed that colorectal cancer induces a tremendous modification of protein expression profiles in the lamina propria. Thus, topological proteomic analysis may help to unravel the role of the adaptive immune system in colorectal cancer and aid the development of new antitumor immunotherapy approaches.

Is there a genetic signature for liver metastasis in colorectal cancer?

Even though liver metastasis accounts for the vast majority of cancer deaths in patients with colorectal cancer (CRC), fundamental questions about the molecular and cellular mechanisms of liver metastasis still remain unanswered. Determination of gene expression profiles by microarray technology has improved our knowledge of CRC molecular pathways. However, defined gene signatures are highly variable among studies. Expression profiles and molecular markers have been specifically linked to liver metastases mechanistic paths in CRC. However, to date, none of the identified signatures or molecular markers has been successfully validated as a diagnostic or prognostic tool applicable to routine clinical practice. To obtain a genetic signature for liver metastasis in CRC, measures to improve reproducibility, to increase consistency, and to validate results need to be implemented. Alternatives to expression profiling with microarray technology are continuing to be used. In the recent past, many genes codifying for proteins that are directly or indirectly involved in adhesion, invasion, angiogenesis, survival and cell growth have been linked to mechanisms of liver metastases in CRC.

Clinical significance of subcellular localization of KL-6 mucin in primary colorectal adenocarcinoma and metastatic tissues

AIM: To assess subcellular localization of KL - 6 mucin and its clinicopathological significance in colorectal carcinoma as well as metastatic lymph node and liver tissues.

METHODS: Colorectal carcinoma tissues as well as metastatic lymph node and liver tissues were collected from 82 patients who underwent colorectomy or hepatectomy. Tissues were subjected to immunohistochemical analysis using KL - 6 antibody.

RESULTS: Of the 82 colorectal carcinoma patients, 6 showed no staining, 29 showed positive staining only in the apical membrane, and 47 showed positive staining in the circumferential membrane and/or cytoplasm. Positive staining was not observed in non - cancerous colorectal epithelial cells surrounding the tumor tissues. The five - year survival rate was significantly lower in cases showing positive staining in the circumferential membrane and/or cytoplasm (63.0%) than those showing positive staining only in the apical membrane (85.7%) and those showing no staining (100%). Statistical analysis between clinicopathological factors and subcellular localization of KL - 6 mucin showed that KL - 6 localization in the circumferential membrane and/or cytoplasm was significantly associated with the presence of venous invasion (P = 0.0003), lymphatic invasion (P <  0.0001), lymph node metastasis (P < 0.0001), liver metastasis (P = 0.058), and advanced histological stage (P < 0.0001). Positive staining was observed in all metastatic lesions tested as well as in the primary colorectal carcinoma tissues.

CONCLUSION: The subcellular staining pattern of KL - 6 in colorectal adenocarcinoma may be an important indicator for unfavorable behaviors such as lymph node and liver metastasis, as well as for the prognosis of patients.

KL-6 mucin expression in carcinoma of the ampulla of Vater: Association with cancer progression

AIM: To assess histochemical expression of KL-6 and its clinicopathological significance in carcinoma of the ampulla of Vater.

METHODS: Ampullary carcinoma tissues were collected from 38 patients who underwent pancreatoduodenectomy or local resection. Tissues were subjected to immunohi-stochemical analysis using KL-6 antibody.

RESULTS: Positive staining of ampullary carcinoma cells was observed in 26 (68.4%) cases. Staining was not found in the surrounding non-cancer regions of the ampullary tissues. Remarkable KL-6 expression was observed in invasive carcinoma cells in pancreatic and duodenal tissues and in metastatic carcinoma cells in lymph nodes. Positive KL-6 expression was related to lymph node metastasis (P = 0.020), pancreatic invasion (P = 0.016), duodenal invasion (P = 0.034), and advanced stage of TNM clinical classification (P = 0.010). Survival analysis showed that positive expression of KL-6 was related to a poorer prognosis (P = 0.029).

CONCLUSION: The aberrant expression of KL-6 mucin is significantly related to unfavorable behaviors of carcinoma of the ampulla of Vater.

Effect of transfected DPC4 gene on angiogenesis of colon carcinoma

AIM: To study the mechanism of transfected DPC4 gene on angiogenesis.

METHODS: SW620 cells were transfected with PcDNA3.1-DPC4 plasmid by using lipofectamine transfecting technique. Expression of Smad4 in DPC₄⁺-SW620 cells was observed by Western blot. The expression of VEGF protein in the cell supernatant was detected by ELISA, and VEGF mRNA by RT-PCR. The model of nude mice inoculated with DPC₄⁺-SW620 cells was established by injecting into flank subcutaneously. The expression of VEGF protein and the microvessel density of tumor tissue in nude mice were detected by immunohistochemical staining (SP method).

RESULTS: DPC₄⁺-SW620 cells expressing Smad4 were harvested; Smad4 protein showed stronger expression in SW620 cells transfected with PcDNA-DPC4 plasmid than that in not-transfected SW620 cells and SW620 cells transfected with blank plasmid, and the positive signal was localized in cytoplasm and nucleus, mainly in cytoplasm; There were lower expression of VEGF protein and mRNA in DPC₄⁺- SW620 cells than that in SW620 cells and PcDNA-SW620 cells (P < 0.05); The model of nude mice inoculated with colon carcinoma cells was established successfully. The tumors of nude mice inoculated with DPC₄⁺-SW620 cells growed more slowly than that inoculated with SW620 cells and PcDNA-SW620 cells. The volume and mass of tumors in nude mice inoculated with DPC₄⁺-SW620 cells were smaller and lighter than those with SW620 cells and PcDNA- SW620 cells (P < 0.05). The expression of VEGF and the microvessel density in DPC₄⁺-SW620 cells were lower than those in SW620 cells and PcDNA-SW620 cells (P < 0.05).

CONCLUSION: The DPC4 gene can suppress the growth of the tumors in nude mice inoculated with DPC₄⁺-SW620 cells; The inhibitory effect of DPC4 on colon carcinoma may be partly mediated by suppressing angiogenesis of tumor.

Screening of human colorectal carcinoma associated antigen genes by SEREX

AIM

To screen and identify the human colorectal carcinoma associated antigen genes.

METHODS

Three human colorectal carcinoma cDNA phage expression libraries were constructed. They were screened from autologous and allogeneic sera of colorectal cancer patients by SEREX (serological identification of antigens by recombinant expression cloning). The sera were pre-absorbed by the extract E. coli XL1-blue. Four different serum-reactive cDNA clones were isolated by immunoscreening from a colon cancer-derived cDNA expression library. Positive clones were amplified by plate culture, the purified lambda phage DNA was cut by Sfi I restriction endonucleases and amplified with PCR in order to identify the insert size of cDNA by electrophresis.

RESULTS

Three cDNA phage expression libraries were constructed. The titer of library was 2.39×10⁶ nfu/L, 2.07×10⁶ nfu/L and 1.86×10⁶ nfu/L respectively, The range of the fragment length of exogenously inserted cDNA was between 0.5-4 kb, the average was 1.4 kb, 1.6 kb and 1.3 kb, respectively. Four gene clones were obtained by SEREX screening, the length of their insert fragments was 2.4 kb, 1.8 kb, 2.3 kb and 2.2 kb, respectively.

CONCLUSION

To screen and identify human colorectal carcinoma cDNA phage expression libraries by SEREX is a useful method to search for human colorectal carcinoma associated antigen genes. It is important for early diagnosis and research of recombinant vaccine for colorectal cancer.

Screening and identification of mimotope of gastric cancer associated antigen MGb1-Ag

AIM: Using a monoclonal antibody against gastric cancer antigen named MGb1 to screen a phage-displayed random peptide library fused with coat protein pIII in order to get some information on mimotopes.

METHODS: Through affinity enrichment and ELISA screening, positive clones of phages were amplified. 10 phage clones were selected after three rounds of biopanning and the ability of specific binding of the positive phage clones to MGb1-Ab were detected by ELISA assay (DNA sequencing was performed and the amino acid sequences were deduced) By blocking test, specificity of the mimic phage epitopes was identified.

RESULTS: There were approximately 200 times of enrichment about the titer of bound phages after three rounds of biopanning procedures. DNA of 10 phage clones after the third biopanning was assayed and the result showed that the positive clones had a specific binding activity to MGb1-Ab and a weak ability of binding to control mAb or to mouse IgG. DNA sequencing of 10 phage clones was performed and the amino acid sequences were deduced. According to the homology of the amino acid sequences of the displayed peptides, most of the phage clones had motifs of H(x)Q or L(x)S. And these 10 phage clones could also partly inhibit the binding of MGb1-Ab to gastric cancer cell KATO-III. The percentage of blocking was from (21.0 ± 1.6)% to (39.0 ± 2.7)%.

CONCLUSION: Motifs of H(x)Q and L(x)S selected and identified show a high homology in the mimic epitopes of gastric cancer associated antigen. There may be one or more clones which can act as candidates of tumor vaccines.

Angiography for diagnosis and treatment of colorectal cancer

AIM: To evaluate the role of preoperative angiography in the diagnosis and treatment of colorectal cancer.

METHODS: The authors performed selective arterial cannulation by Seldinger's method in 47 patients to locate the primary cancer and to diagnose metastasis to the liver. Each patient was then given intra-arterial regional chemotherapy, and received 5-fluorouracil (5-Fu, 1000 mg), mitomycin C (MMC, 20 mg), and cisplatinum (CDDP, 80 mg).

RESULTS: The location and shape of each tumor were observed, including metastatic tumors in the liver, in 42 of the 47 (89.4%) patients. The site of the primary tumor was difficult to identify in 5 cases because the patients had a recurrence of cancer. Arterial chemotherapy was performed successfully in all patients. The authors recorded no partial or significant morbidity resulted from angiography. The only incident was bleeding from the artery puncture site in one patient, which was successfully stopped by general medication.

CONCLUSION: Preoperative selective arterial angiography can help the diagnosis and locate primary tumors and to detect liver metastasis. At the same time, regional arterial chemotherapy can be an important form of preoperative therapy.

Current treatment for liver metastases from colorectal cancer

The liver is the commonest site of distant metastasis of colorectal cancer and nearly half of the patients with colorectal cancer ultimately develop liver involved during the course of their diseases. Surgery is the only therapy that offers the possibility of cure for patients with hepatic metastatic diseases. Five-year survival rates after resection of all detectable liver metastases can be up to 40%. Unfortunately, only 25% of patients with colorectal liver metastases are candidates for liver resection, while the others are not amenable to surgical resection. Regional therapies such as radiofrequency ablation and cryotherapy may be offered to patients with isolated unresectable metastases but no extrahepatic diseases. Hepatic artery catheter chemotherapy and chemoembolization and portal vein embolization are often used for the patients with extensive liver metastases but without extrahepatic diseases, which are not suitable for regional ablation. For the patients with metastatic colorectal cancer beyond the liver, systemic chemotherapy is a more appropriate choice. Immunotherapy is also a good option when other therapies are used in combination to enhance the efficacy. Selective internal radiation therapy is a new radiation method which can be used in patients given other routine therapies without effects.

Arterial chemotherapy of 5-fluorouracil and mitomycin C in the treatment of liver metastases of colorectal cancer

AIM: Regional chemotherapy using hepatic artery catheters is a good method of treating patients with colorectal cancer liver metastases. We investigated the survival of patients with liver metastases from colorectal cancer using 5-fluorouracil (5-FU) and mitomycin C Cthrough implantable hepatic arterial infusion port.

METHODS: Seventy-five patients with inoperable liver metastases from colorectal cancer were included between March, 1992 and November, 2001. We placed implantable hepatic arterial catheter (HAC) port by laparotomy.5-FU, 1000 mg/m²/d continuous infusion for five days every four weeks, was delivered in the hepatic arterial catheter through the port. Mitomycin C, 30 mg/m²/d infusion in the first day every cycle through the port. Response to the treatment was evaluated by serial determinations of plasma CEA and imaging techniques consisting of computerized tomography and sonography of liver.

RESULTS: Sixty-eight were performed hepatic artery chemotherapy and fifty-six were followed up among seventy-five HAC patients. Twenty-six patients (46.4%) have responded and 4 complete remission were achieved. Eight patients (14.3%) had stable liver metastases. Twenty-two patients (39.3%) were progressed with increased tumor size and number. Twenty-nine patients (51.8%) had a decreased serum CEA level, while 10 patients (17.9%) were stable and 17 patients (30.4%) had an increased serum CEA level. There were no operative death in this series. Complications, which occurred in 18 patients (32.1%), were as followed: hepatic artery thrombosis in 11, Upper gastric and intestinal bleeding in 3, liver abscess in 1, pocket infection in 1, cholangitis in 1, and hepatic artery pseudo-aneurysm in one patient.

CONCLUSION: Combined infusion of 5-FU and mitomycin C by hepatic artery catheter port is an effective treatment for liver metastases from colorectal cancer. The high response and lower complication rates prove the adjuvant treatment of colorectal cancer with this treatment.

Hepatoprotective role of ganoderma lucidum polysaccharide against BCG-induced immune liver injury in mice

AIM: To examine the effect of ganoderma lucidum polysaccharide (GLP) on the immune liver injury induced by BCG infection, and investigate the relationship between degrees of hepatic damage and NO production in mice.

METHODS: Immune hepatic injury was markedly induced by BCG-pretreatment (125 mg·kg^-1, 2-week, iv) or by BCG-pretreatment plus lipopolysaccharide (LPS, 125 μg·kg^-1, 12-hour, iv) in mice in vivo. Hepatocellular damage induced by BCG-pretreated plus inflammatory cytokines mixture (CM), which was included TNF-α, IL-1β, IFN-γ and LPS in culture medium in vitro. Administration of GLP was performed by oral or incubating with culture medium at immune stimuli simultaneity. Liver damage was determined by activity of alanine aminotransferase (ALT) in serum and in hepatocytes cultured supernatant, by liver weight changes and histopathological examination. NO production in the cultured supernatant was determined by the Griess reaction. Moreover, inducible nitric oxide synthase (iNOS) protein expression was also examinated by immunohistochemical method.

RESULTS: Immune hepatic injury was markedly induced by BCG or BCG plus inflammatory cytokines in BALB/c mice in vivo and in vitro. Under BCG-stimulated condition, augment of the liver weight and increase of the serum/supernatant ALT level were observed, as well as granuloma forming and inflammatory cells soakage were observed by microscopic analysis within liver tissues. Moreover, NO production was also increased by BCG or/and CM stimuli in the culture supernatant, and a lot of iNOS positive staining was observed in BCG-prestimulated hepatic sections. Application of GLP significantly mitigated hepatic tumefaction, decreased ALT enzyme release and NO production in serum/supernatant, improved the pathological changes of chronic and acute inflammation induced by BCG-stimuli in mice. Moreover, the immunohistochemical result showed that GLP inhibited iNOS protein expression in BCG-immune hepatic damage model.

CONCLUSION: The present study indicates that NO participates in immune liver injury induced by Mycobacterium bovis BCG infection. The mechanisms of protective roles by GLP for BCG-induced immune liver injury may be due to influence NO production in mice.