Drug resistance and new therapies in colorectal cancer

Colorectal cancer(CRC) is often diagnosed at an advanced stage when tumor cell dissemination has taken place. Chemo-and targeted therapies provide only a limited increase of overall survival for these patients. The major reason for clinical outcome finds its origin in therapy resistance. Escape mechanisms to both chemo-and targeted therapy remain the main culprits. Here, we evaluate major resistant mechanisms and elaborate on potential new therapies. Amongst promising therapies is α-amanitin antibodydrug conjugate targeting hemizygous p53 loss. It becomes clear that a dynamic interaction with the tumor microenvironment exists and that this dictates therapeutic outcome. In addition, CRC displays a limited response to checkpoint inhibitors, as only a minority of patients with microsatellite instable high tumors is susceptible. In this review, we highlight new developments with clinical potentials to augment responses to checkpoint inhibitors.

Establishment of organoid models based on a nested array chip for fast and reproducible drug testing in colorectal cancer therapy

The conventional microwell-based platform for construction of organoid models exhibits limitations in precision oncology applications because of low-speed growth and high variability. Here, we established organoid models on a nested array chip for fast and reproducible drug testing using 50% matrigel. First, we constructed mouse small intestinal and colonic organoid models. Compared with the conventional microwell-based platform, the mouse organoids on the chip showed accelerated growth and improved reproducibility due to the nested design of the chip. The design of the chip provides miniaturized and uniform shaping of the matrigel that allows the organoid to grow in a concentrated and controlled manner. Next, a patient-derived organoid(PDO) model from colorectal cancer tissues was successfully generated and characterized on the chip. Finally, the PDO models on the chip, from three patients, were implemented for high-throughput drug screening using nine treatment regimens. The drug sensitivity testing on the PDO models showed good quality control with a coefficient of variation under 10% and a Z’ factor of more than 0.7. More importantly, the drug responses on the chip recapitulate the heterogeneous response of individual patients, as well as showing a potential correlation with clinical outcomes. Therefore,the organoid model coupled with the nested array chip platform provides a fast and reproducible means for predicting drug responses to accelerate precise oncology.

Gene therapy for human colorectal carcinoma using human CEA promoter controlled bacterial ADP-ribosylating toxin genes:PEA and DTA gene transfer

AIM To establish a tissue-specific gene therapy for colorectal carcinoma using bacterial ADP-ribosylating toxin genes.METHODS Pseudomonas exotoxin A domain Ⅱ+Ⅲ (PEA) was cloned from genomic DNA of Pseudomonas aeruginosa. PEA and diphtheria toxin A chain gene (DTA) were modified to express eukaryotically. After sequencing, the toxin genes under the control of human carcinoembryonic antigen (CEA) promoter were cloned into retroviral vectors to construct CEAPEA and CEADTA respectively. In vitro cotransfection of the constructs with luciferase vectors and in vivo gene transfer in nude mice were subsequently carried out.RESULTS Both CEAPEA and CEADTA specifically inhibited the reporter gene expression in the CEA positive human colorectal carcinoma (CRC) cells in vitro. Direct injection of CEAPEA and CEADTA constructs into the established human tumors in BALB/c nude mice led to significant and selective reductions in CRC tumor size as compared with that in control groups.CONCLUSION The toxin genes, working as therapeutic genes, are suitable for the tissue-specific gene therapy for colorectal carcinoma.

Application of rational emotive behavior therapy in patients with colorectal cancer undergoing adjuvant chemotherapy

Objective:This study aimed to explore the effects of our rational emotive behavior therapy(REBT)program on symptoms,anxiety,depression,and sleep state in patients with colorectal cancer(CRC)undergoing chemotherapy.Methods:From October 2020 to May 2021,fifty-six patients with CRC in a hospital in the Hunan Province were randomly divided into an intervention group(n=28)and a control group(n=28).The patients in the intervention group completed a 6-week REBT program based on routine nursing care,including four courses:1)establish a relationship and formulate health files;2)group communications and study symptom management;3)continuously provide health knowledge and strengthen healthy behavior;and 4)review the treatment and summary.The control group maintained routine nursing care.The simplified Chinese version of the Memorial Symptom Assessment Scale Short Form(MSASeSFeSC),the Hospital Anxiety and Depression Scale(HADS),and the Pittsburgh Sleep Quality Index(PSQI)scale were used to investigate and compare the intervention effects of the two groups at baseline(T1,before the intervention),four weeks(T2),and six weeks(T3)after the intervention.Results:The intervention group was significantly improved in symptoms,anxiety,depression,and sleep state,compared with the control group.At T2,MSASeSFeSC(24.43±4.26 vs.28.07±3.91),symptom distress(17.29±4.04 vs.19.39±3.59),symptom frequency(7.14±1.51 vs.8.68±1.42),HADS(13.68±3.38 vs.15.86±3.79),anxiety(3.89±1.85 vs.5.18±2.18),and depression(9.79±2.06 vs.10.68±2.23),showed that the difference between the two groups was statistically significant(P<0.05).At T3,MSASeSFeSC(23.89±3.54 vs.30.14±3.94),symptom distress(17.61±3.52 vs.21.32±3.57),symptom frequency(6.29±1.49 vs.8.82±1.47),HADS(11.82±2.57 vs.16.29±3.13),anxiety(3.21±1.64 vs.5.61±1.77),and depression(8.61±1.52 vs.10.68±1.81),showed that the difference between the two groups was statistically significant(P<0.05).The sleep state of the intervention group was better than the control group at T3,with decreased score of PSQI[4.00(3.00,8.00)vs.9.00(7.00,12.50),Z=-3.706,P<0.001].Conclusion:The 6-week REBT program can effectively improve the symptom,anxiety,depression,and sleep state of patients with CRC undergoing chemotherapy,which could as a care plan for patients with CRC who are repeatedly admitted to the hospital for chemotherapy.

Efficacy of neoadjuvant chemotherapy for initially resectable colorectal liver metastases:A retrospective cohort study

BACKGROUND The liver is the most common metastatic site of colorectal cancer.Hepatectomy is the mainstay of treatment for patients with colorectal liver metastases(CRLMs).However,there are cases of early recurrence after upfront hepatectomy alone.In selected high-risk patients,neoadjuvant chemotherapy(NAC)may improve longterm survival.AIM To determine the efficacy of NAC for initially resectable CRLMs.METHODS Among 644 patients who underwent their first hepatectomy for CRLMs at our institution,297 resectable cases were stratified into an upfront hepatectomy group(238 patients)and a NAC group(59 patients).Poor prognostic factors for upfront hepatectomy were identified using multivariate logistic regression analysis.Propensity score matching was used to compare clinical outcomes between the upfront hepatectomy and NAC groups,according to the number of poor prognostic factors.Survival curves were estimated using the Kaplan-Meier method and compared using the log-rank test.RESULTS Preoperative carcinoembryonic antigen levels(≥10 ng/mL)(P=0.003),primary histological type(other than well/moderately differentiated)(P=0.04),and primary lymph node metastases(≥1)(P=0.04)were identified as independent poor prognostic factors for overall survival(OS)in the upfront hepatectomy group.High-risk status was defined as the presence of two or more risk factors.After propensity score matching,50 patients were matched in each group.Among high-risk patients,the 5-year OS rate was significantly higher in the NAC group(13 patients)than in the upfront hepatectomy group(18 patients)(100%vs 34%;P=0.02).CONCLUSION NAC may improve the prognosis of high-risk patients with resectable CRLMs who have two or more risk factors.

Experimental study on effect of recombinant human growth hormone combined with chemotherapy on stomach neoplasms implanted in nude mice

Objective: To investigate the effect of different doses of recombined growth hormone (rhGH) on stomach neo- plasms implanted in nude mice, and its efficacy in combining with chemotherapy (flurouracil, 5-FU). Methods: Human stom- ach neoplasms model was established in nude mice. The nude mice were divided into control group, moderate-dose of rhGH group, low-dose rhGH group, 5-FU group, moderate-dose rhGH/5-FU group, and low-dose rhGH/5-FU group. The results of each group were observed after ten days. Results: After therapy, the body mass of rhGH groups was significantly increased compared with control group (P<0.05), the body mass of rhGH/5-FU groups was significantly increased compared with 5-FU group (P<0.05), but it was no significant difference between rhGH/5-FU groups and control group (P>0.05). The average tumor mass and volume of rhGH groups were not significantly increased compared with control group (P>0.05), but they were significantly reduced in 5-FU group and rhGH/5-FU groups (P<0.05). They were no significant difference between rhGH/5- FU groups and 5-FU group (P>0.05). After treatment, the percentages of S, G0/G1 and G2/M phases and proliferation index (PI) were not significantly changed in rhGH groups compared with control group (P>0.05), and the same with rhGH/5-FU groups compared with 5-FU group (P>0.05). The difference caused by dose of rhGH was not significant. Conclusion: rhGH enhances body mass, does not stimulate tumor growth, and has no adverse effects on tumor bearing nude mice. Combined with flurouracil, rhGH does not influence the efficacy of chemotherapy, and has no effect on tumor cell cycle kinetics.

Micelles as potential drug delivery systems for colorectal cancer treatment

Despite the significant progress in cancer therapy,colorectal cancer(CRC)remains one of the most fatal malignancies worldwide.Chemotherapy is currently the mainstay therapeutic modality adopted for CRC treatment.However,the long-term effectiveness of chemotherapeutic drugs has been hampered by their low bioavailability,non-selective tumor targeting mechanisms,non-specific biodistribution associated with low drug concentrations at the tumor site and undesirable side effects.Over the last decade,there has been increasing interest in using nanotechnology-based drug delivery systems to circumvent these limitations.Various nanoparticles have been developed for delivering chemotherapeutic drugs among which polymeric micelles are attractive candidates.Polymeric micelles are biocompatible nanocarriers that can bypass the biological barriers and preferentially accumulate in tumors via the enhanced permeability and retention effect.They can be easily engineered with stimuli-responsive and tumor targeting moieties to further ensure their selective uptake by cancer cells and controlled drug release at the desirable tumor site.They have been shown to effectively improve the pharmacokinetic properties of chemotherapeutic drugs and enhance their safety profile and anticancer efficacy in different types of cancer.Given that combination therapy is the new strategy implemented in cancer therapy,polymeric micelles are suitable for multidrug delivery and allow drugs to act concurrently at the action site to achieve synergistic therapeutic outcomes.They also allow the delivery of anticancer genetic material along with chemotherapy drugs offering a novel approach for CRC therapy.Here,we highlight the properties of polymeric micelles that make them promising drug delivery systems for CRC treatment.We also review their application in CRC chemotherapy and gene therapy as well as in combination cancer chemotherapy.

Rationally designed treatment for metastatic colorectal cancer:Current drug development strategies

The therapeutic landscape of metastatic colorectal cancer(mCRC)has changed substantially with the emergence of new molecularly targeted agents(MTA)usedas single agents or alongside standard chemotherapy.The use of these MTAs extended the overall survival ofpatients with mCRC to a level that current chemotherapeutics alone could not achieve.In addition,improvement in surgical techniques and ablation modalities offer cure to a limited subset of patients with mCRC andMTAs have been found to have a significant role heretoo,as they aid resectability.However,for the majority of patients,mCRC remains an invariably incurabledisease necessitating continued courses of combinedtreatment modalities.During the course of these treatments,either cytotoxic or biological,cancer cells maintain their ability to acquire mitogenic mutations whichrender them resistant to treatment.Key challengesremain to identify appropriate subsets of patients whowill most likely benefit from these new MTAs and effectively select these based on validated biomarkers.Moreover,better knowledge of the biology of colorectal cancer and the mechanisms via which it bypasses blockade of known signalling pathways will help us design better and more rational sequencing of these treatments,so that we can maximise the survivorship of mCRC patients.This review outlines treatment strategies for known molecular alterations with new MTAs and highlights some promising strategies.

Value of selective chemoembolization in treatment of hepatic metastases in colorectal carcinoma

AIM To explore the therapeutic effect of chemoembolization in hepatic metastases in colorectal carcinoma. METHODS Forty patients underwent chemoembolization of metastatic liver lesion from colorectal carcinoma. Selective angiography of the hepatic artery was performed to identify the feeding vessels of the metastatic lesion. The injected chemoemulsum consisted of 100*!mg 5 fluorouracil, 10*!mg mitomycin C and 10*!mL lipiodol ultra fluid in a total volume of 30*!mL . Gel foam embolization then followed until stagnation of blood flow was achieved. Patients were evaluated for response, over all survival, and side effects. RESULTS Overall median survival time from date of first chemoembolization was ten months. Median survival time of cirrhotic patients with class A and B by Child Pugh classification was 24 and 3 months, respectively. The difference was significant, ( P <0 01) . Patients with metastatic disease confined to the liver did better than those who also had extrahepatic disease, with median survivals of 14 and 3 months, respectively ( P <0 02) . There were significant differences in that median survival of patients with hypervascular metastases was longer than that of patients with hypovascular metastases. The most common side effects were transient fever, abdominal pain and fatigue. Three patients died within one month from the procedure. CONCLUSION The therapeutic effect of systemic chemotherapy in hepatic metastases of large intestinal carcinoma was not satisfactory and there were more side effects, whereas the therapeutic effect of selective chemoembolization was promising and there were less side effects. Selective chemoembolization may be an effective first line therapy in hepatic metastases of large intestinal carcinoma.

Colorectal cancer: From prevention to personalized medicine

Colorectal cancer(CRC)is a very heterogeneous disease that is caused by the interaction of genetic and environmental factors.CRC develops through a gradual accumulation of genetic and epigenetic changes,leading to the transformation of normal colonic mucosa into invasive cancer.CRC is one of the most prevalent and incident cancers worldwide,as well as one of the most deadly.Approximately 1235108 people are diagnosed annually with CRC,and 609051 die from CRC annually.The World Health Organization estimates an increase of77%in the number of newly diagnosed cases of CRCand an increase of 80%in deaths from CRC by 2030.The incidence of CRC can benefit from different strategies depending on its stage:health promotion through health education campaigns(when the disease is not yet present),the implementation of screening programs(for detection of the disease in its early stages),and the development of nearly personalized treatments according to both patient characteristics(age,sex)and the cancer itself(gene expression).Although there are different strategies for screening and although the number of such strategies is increasing due to the potential of emerging technologies in molecular marker application,not all strategies meet the criteria required for screening tests in population programs;the three most accepted tests are the fecal occult blood test(FOBT),colonoscopy and sigmoidoscopy.FOBT is the most used method for CRC screening worldwide and is also the primary choice in most population-based screening programs in Europe.Due to its non-invasive nature and low cost,it is one of the most accepted techniques by population.CRC is a very heterogeneous disease,and with a few exceptions(APC,p53,KRAS),most of the genes involved in CRC are observed in a small percentage of cases.The design of genetic and epigenetic marker panels that are able to provide maximum coverage in the diagnosis of colorectal neoplasia seems a reasonable strategy.In recent years,the use of DNA,RNA and protein markers in different biological samples has been explored as strategies for CRC diagnosis.Although there is not yet sufficient evidence to recommend the analysis of biomarkers such as DNA,RNA or proteins in the blood or stool,it is likely that given the quick progression of technology tools in molecular biology,increasingly sensitive and less expensive,these tools will gradually be employed in clinical practice and will likely be developed in mass.

Apoptotic pathways as a therapeutic target for colorectal cancer treatment

Colorectal cancer is the second leading cause of death from cancer among adults. The disease begins as a benign adenomatous polyp, which develops into an advanced adenoma with high-grade dysplasia and then progresses to an invasive cancer. Appropriate apoptotic signaling is fundamentally important to preserve a healthy balance between cell death and cell survival and in maintaining genome integrity. Evasion of apoptotic pathway has been established as a prominent hallmark of several cancers. During colorectal cancer development, the balance between the rates of cell growth and apoptosis that maintains intestinal epithelial cell homeostasis gets progressively disturbed. Evidences are increasingly available to support the hypothesis that failure of apoptosis may be an important factor in the evolution of colorectal cancer and its poor response to chemotherapy and radiation. The other reason for targeting apoptotic pathway in the treatment of cancer is based on the observation that this process is deregulated in cancer cells but not in normal cells. As a result, colorectal cancer therapies designed to stimulate apoptosis in target cells would play a critical role in controlling its development and progression. A better understanding of the apoptotic signaling pathways, and the mechanisms by which cancer cells evade apoptotic death might lead to effective therapeutic strategies to inhibit cancer cell proliferation with minimal toxicity and high responses to chemotherapy. In this review, we analyzed the current understanding and future promises of apoptotic pathways as a therapeutic target in colorectal cancer treatment.

Liver-first approach of colorectal cancer with synchronous hepatic metastases: A reverse strategy

Recently, there has been a change in the strategy of how synchronous colorectal hepatic metastases are attributed to the development of more valuable protocols of chemotherapy and radiotherapy for neoadjuvant treatment of colorectal neoplasms and their hepatic metastases. There is a consensus that patients with synchronous colorectal hepatic metastases have lower survival than those with metachronous colorectal hepatic metastases. Currently, controversy remains concerning the best approach is sequence in a patient with colorectal cancer and synchronous hepatic metastases resection. To obtain a better patient selection, the authors have suggested the initial realization of systemic chemotherapy in the circumstance of patients with colorectal tumor stage Ⅳ, since these patients have a systemic disease. The rationale behind this liver-first strategy is initially the control of synchronous hepatic metastases of colorectal carcinoma, which can optimize a potentially curative hepatic resection and longstanding survival. The liver-first strategy procedure is indicated for patients with colorectal hepatic metastases who require downstaging therapy to make a curative liver resection possible. Thus, the liver-first strategy is considered an option in cases of rectal carcinoma in the early stage and with limited or advanced synchronous colorectal hepatic metastases or in case of patients with asymptomatic colorectal carcinoma, but with extensive liver metastases. Patients undergoing systemic chemotherapy and with progression of neoplastic disease should not undergo hepatic resection, because it does not change the prognosis and may even make it worse. To date, there have been no randomized controlled trials on surgical approach of colorectal synchronous hepatic metastases, despite the relatively high number of available manuscripts on this subject. All of these published studies are observational, usually retrospective, and often non-comparative. The patient selection criteria for the liver-first strategy should be individualized, and the approach of these patients should be performed by a multidisciplinary team so its benefits will be fully realized.

Trans-arterial chemoperfusion for the treatment of liver metastases of breast cancer and colorectal cancer: Clinical results in palliative care patients

AIM To evaluate the clinical value and efficiency of transarterial chemoperfusion(TACP) in patients with liver metastases from breast cancer(BC) and colorectal cancer(CRC).METHODS We treated 36 patients with liver metastases of BC(n = 19, 19 females) and CRC(n = 17; 8 females, 9 males) with repeated TACP. The treatment interval was 4 wk. TACP was performed with gemcitabine(1000 mg/m2) and mitomycin(10 mg/m2), administered within 1 h after positioning the catheter tip in the hepatic artery. Before treatment, the size, location, tumour volume, vascularization and number of liver tumours were evaluated using magnetic resonance imaging(MRI). Tumour response was evaluated according to the Response Evaluation Criteria in Solid Tumors guidelines.RESULTS TACP using gemcitabine and mitomycin for metastases from CRC and BC was performed without any serious side effects. The follow-up MRI showed a therapeutic response in 84.2% of the BC patients-stable disease 47.4% and partial response 36.8%. A progression was seen in 15.8%.CRC patients showed a therapeutic response in 52.9% of cases. A progression of the disease was documented in 47.1% of the patients with CRC. These data show that TACP in patients with liver metastases of BC leads to a significantly better therapeutic response compared with CRC patients(P = 0.042). The median survival time was 13.2 mo for the BC patients, which is significantly longer than for CRC patients at 9.3 mo(P = 0.001).CONCLUSION TACP for liver metastases of BC appears to be a safe and effective palliative treatment with improved outcomes in comparison to patients with CRC.

Inhibitory effects of EGFR antisense oligodeoxynucleotide in human colorectal cancer cell line

INTRODUCTIONEpidermal-growth-factor receptor(EGFR) is apolypeptide with 1186 amino acids,which binds toEGF family growth factors.Two major naturalligands in the family interact with EGFR:one isEGF,the other is transforming growth factor-α(TGF-α).When EGF or TGF-α,binds to EGFR,tyrosine kinase activity is induced which in turntriggers a series of events regulating the cellgrowth.The importance of EGFR in growthregulating pathways was confirmed by the fact

Specific CEA-producing colorectal carcinoma cell killing with recombinant adenoviral vector containing cytosine deaminase gene

AIM: To kill CEA positive colorectal carcinoma cells specifically using the E coli cytosine deaminase (CD) suicide gene, a new replication-deficient recombinant adenoviral vector was constructed in which CD gene was controlled under CEA promoter and its in vitro cytotoxic effects were evaluated. METHODS: Shuttle plasmid containing CD gene and regulatory sequence of the CEA gene was constructed and recombined with the right arm of adenovirus genome DNA in 293 cell strain. Dot blotting and PCR were used to identify positive plaques. The purification of adenovirus was performed with ultra-concentration in CsCl step gradients and the titration was measured with plaque formation assay. Cytotoxic effects were assayed with MTT method, The fifty percent inhibition concentration (IC(50)) of 5-FC was calculated using a curve-fitting parameter. The human colorectal carcinoma cell line, which was CEA-producing, and the CEA-nonproducing Hela cell line were applied in cytological tests. An established recombinant adenovirus vector AdCMVCD, in which the CD gene was controlled under CMV promoter, was used as virus control. Quantitative results were expressed as the mean +/- SD of the mean. Statistical analysis was performed using ANOVA test. RESULTS: The desired recombinant adenovirus vector was named AdCEACD. The results of dot blotting and PCR showed that the recombinant adenovirus contained CEA promoter and CD gene. Virus titer was about 5.0 X 10(14)pfu/L(-1) after purification. The CEA-producing Lovo cells were sensitive to 5-FC and had the same cytotoxic effect after infection with AdCEACD and AdCMVCD (The IC(50) values of 5-FC in parent Lovo cells, Lovo cells infected with 100 M.O.I AdCEACD and Lovo cells infected with 10 M.O.I AdCMVCD were 】15000, 216.5+/-38.1 and 128.8+/-25.4 micromol.L(-1), P【0.001, respectively), and the cytotoxicity of 5-FC increased accordingly when the m.o.i of adenoviruses were enhanced (The value of IC(50) of 5-FC was reduced to 27.9+/-4.2 micromol.L(-1) in 1000 M.O.I AdCEACD infected Lovo cells and 24.8+/-7.1 micromol.L(-1) in 100 M.O.I AdCMVCD infected Lovo cells, P【0.05, P【0.01, respectively). The CEA-nonproducing Hela cells had no effect after infection with AdCEACD, but Hela cells had the cytotoxic sensitivity to 5-FC after infection with AdCMVCD (The IC(50) of 5-FC in parent Hele cells and Hela cells infected with AdCMVCD at 10 M.O.I was 】15000 and 214.5+/-31.3 micromol.L(-1), P【0.001). AdCEACD/5-FC system also had bystander effect, and the viability was about 30 percent when the proportion of transfected cells was only 10 percent. CONCLUSION: The recombinant adenovirus vector AdCEACD has the character of cell type-specific gene delivery. The AdCEACD/5-FC system may become a new, potent and specific approach for the gene therapy of CEA-positive neoplasms, especially colon carcinoma.

Autophagy-related proteins Beclin-1 and LC3 predict cetuximab efficacy in advanced colorectal cancer

AIM:To investigate the utility of Beclin-1 and LC3,two autophagy-related proteins,in predicting the cetuximab efficacy in advanced colorectal cancer(ACRC) . METHODS:The data of 85 patients with ACRC treated at the Sun Yat-sen University Cancer Center from March 1,2005 to December 31,2008 were studied,including 45 cases treated with cetuximab-containing chemotherapy and 40 cases treated with non-cetuximab-containing chemotherapy.Beclin-1 and LC3 expression was evaluated by immunohistochemistry,and KRAS status was evaluated by polymerase chain reaction. RESULTS:Beclin-1 and LC3 expression in ACRC wassignificantly correlated(r=0.44,P<0.01);however,LC3 was more highly expressed in cancerous tissues than in normal tissues(Z=-2.63,P<0.01) .In the cetuximab-containing chemotherapy group,patients with low LC3 expression had higher objective response rates(ORRs) than those with high LC3 expression(52.9%vs 17.9%,P=0.01) ,and patients with low Beclin-1 expression had a longer median progressionfree survival(PFS) than their counterparts with higher Beclin-1 expression(9.0 mo vs 3.0 mo,P=0.01) . However,neither of these predictive relationships was detected in the group treated with non-cetuximabcontaining chemotherapy.Patients with wild-type KRAS had higher ORRs(42.3%vs 9.1%,P=0.049) and disease control rates(DCRs)(73.1%vs 36.4%,P= 0.035) ,and longer median PFS(5.5 mo vs 2.5 mo,P= 0.02) than those with mutant KRAS in the cetuximabcontaining chemotherapy group.Neither Beclin-1(P= 0.52) nor LC3(P=0.32) expression was significantly correlated with KRAS status. CONCLUSION:Patients with low Beclin-1 expression had a longer PFS than those with high Beclin-1 expression,and patients with low LC3 expression had a higher ORR in ACRC patients treated with cetuximab-containing chemotherapy.

Effect of a nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester on invasion of human colorectal cancer cell line SL-174T

AIML To investigate the effect and mechanism of action of the nitric oxide synthase （NOS） inhibitor NG-nitro-L-arginine methyl ester （L-NAME） on invasion and metastasis of human colorectal cancer cell line SL-174T. METHODS： Human colorectal cancer cel4 line SL-174T was cultured and treated separately with four different dosages of L-NAME for 72 h, Nitric oxide （NO） production was measured with Griess reagent, The effect of L-NAME on invasion and migration of SL-174T cells were evaluated by using Transwell chambers attached with polycarbonate filters and reconstituted basement membrane （Matrigel）, RT-PCR was performed to determine the mRNA levels of matrix metalloproteinase-2 （MMP-2） and tissue inhibitor metalloproteinase-2 （TIMP-2）,RESULTS： L-NAME could significantly inhibit NO production of SL-174T in a dose-dependent manner. After being treated for 72 h with 0.2, 0.4, 0.8, and 1.0 mmol/L L- NAME, respectively, the ability of the L-NAME treated SL- 174T cells to invade the reconstituted basement membrane decreased significantly （t = 8.056, P〈0.05; t= 14.467, P〈0.01; t= 27.785, P〈0.01; and t= 29.405, P〈0.01, respectively） and the inhibition rates were 10.29%, 19.62%, 34.08%, and 42.23%, respectively. Moreover, L-NAME could inhibit migration of SL-174T cells, and the inhibition rates were 20.76%, 24.95%, 39.43%, and 46. 85% for L-NAME at 0.2, 0.4, 0.8, and 1.0 mmol/L, respectively （t = 15.116, P〈0.01）. In addition, after treatment with L-NAME, expression of MMP-2 mRNA was significantly decreased （t = 71.238, P〈0.01） and that of TIMP-2 mRNA was markedly increased （t = -13.020, P〈0.01）. CONCLUSION： L-NAME exerts anti-invasive and anti- metastatic effects on SL-174T cell line via downregulating MNP-2 mRNA expression and upregulating TIMP-2 mRNA expression.

Glycogen Synthase Kinase 3β Inhibitor (2'Z,3'E)-6-Bromo-indirubin-3'-Oxime Enhances Drug Resistance to 5-Fluorouracil Chemotherapy in Colon Cancer Cells

Objective： To explore the effects and mechanism of glycogen synthase kinase 3β （GSK-313） inhibitor （2＇Z,3＇E）-6-bromo-indirubin-3＇-oxime （BIO） on drug resistance in colon cancer cells. Methods： The colon cancer SW480 and SW620 cells were treated with BIO, 5-fluorouracil （5-FU） and BIO/5-FU, separately. Cell cycle distribution, apoptosis level and efflux ability of rhodamine 123 （Rh123） were detected by flow cytometry. The protein expressions of P-glycoprotein （P-gp）, multidrug resistance protein 2 （MRP2）, thymidylate synthase （TS）, β-catenin, E2F-1 and βcl-2 were detected by Western blot. β-catenin and P-gp were stained with double immunofluorescence and observed under a confocal microscope. Results： BIO up-regulated β-catenin, P-gp, MRP2 and TS, enhanced the efflux ability of Rh123, decreased Bcl-2 protein and gave the opposite effect to E2F-1 protein in SW480 and SW620 ceils. Furthermore, BIO significantly inhibited cell apoptosis, increased S and G2/M phase cells, and reduced the cell apoptosis induced by 5-FU in SW480 cells, whereas the effects were slight or not obvious in SW620 cells. Conclusion： GSK-3β was involved in drug resistance regulation, and activation of β-catenin and inhibition of E2F-1 may be the most responsible for the enhancement of 5-FU chemotherapy resistance induced by GSK-β inhibitor β10 in colon cancer.

Feasibility and Efficacy Study of Biweekly Irinotecan Combined with Oral Tegafur/Uracil in Advanced Colorectal Cancer

Background: We evaluated the feasibility and efficacy of irinotecan (CPT-11) plus tegafur/uracil (UFT) combination chemotherapy in patients with advanced colorectal cancer. Patients and Methods: PK parameters were concurrently measured to confirm the presence of drug interactions in this treatment schedule. CPT-11 was administered intravenously at the dose of 150 mg/m2 on days 1, 15. UFT was administered at the dose of 375 mg/m2/day (B.I.D.) on days 3 - 7, 10 - 14, 17 - 21, 24 - 28 repeated every 5 weeks. Results: 31 patients were enrolled. PK parameters for CPT-11, FT, 5-FU and uracil are available from 5 patients. The overall response rate was 16.1%. The median time to treatment discontinuation was 3.9 months. There was no significant difference in PK parameters of CPT-11 between day 1 and day 15 and of UFT between day 3 and day 10. Conclusion: CPT-11 plus UFT combination chemotherapy exhibited a tolerable toxicity profile with acceptable efficacy. Pharmacokinetic analysis showed that there were no drug interactions in this treatment schedule.

Postoperative chemoradiotherapy with capecitabine and oxaliplatin vs.capecitabine for pathological stage N2 rectal cancer

Objective:Several studies have been conducted on the effects and toxicity of adding oxaliplatin to fluorouracilbased or capecitabine-based chemoradiotherapy(CRT)regimens as significantly increasing the toxic response without benefit to survival.In this study,we further explored the role of these two postoperative CRT regimens in patients with pathological stage N2 rectal cancer.Methods:This study was a subgroup analysis of a randomized clinical trial.A total of 180 patients with pathological stage N2 rectal cancer were eligible,85 received capecitabine with radiotherapy(RT),and 95 received capecitabine and oxaliplatin with RT.Patients in both groups received adjuvant chemotherapy[capecitabine and oxaliplatin(XELOX);or fluorouracil,leucovorin,and oxaliplatin(FOLFOX)]after CRT.Results:At a median follow-up of 59.2[interquartile range(IQR),34.0−96.8]months,the three-year diseasefree survival(DFS)was 53.3%and 64.9%in the control group and the experimental group,respectively[hazard ratio(HR),0.63;95%confidence interval(95%CI),0.41−0.98;P=0.04].There was no significant difference between the groups in overall survival(OS)(HR,0.62;95%CI,0.37−1.05;P=0.07),the incidence of locoregional recurrence(HR,0.62;95%CI,0.24−1.64;P=0.33),the incidence of distant metastasis(HR,0.67;95%CI,0.42−1.06;P=0.09)and grade 3−4 acute toxicities(P=0.78).For patients with survival longer than 3 years,the conditional overall survival(COS)was significantly better in the experimental group(HR,0.39;95%CI,0.16−0.96;P=0.03).Conclusions:Our results indicated that adding oxaliplatin to capecitabine-based postoperative CRT is safe and effective in patients with pathological stage N2 rectal cancer.