Pharmacogenetics research on chemotherapy resistance in colorectal cancer over the last 20 years

Quantitative bioanalytical LC–MS/MS assay for S130 in rat plasma-application to a pharmacokinetic study

Aim: An innovative Atg4B inhibitor, S130, exhibited a negative influence on colorectal cancer cells in vitro and in vivo. To assist reliable toxicodynamic and pharmacokinetic evaluation, an LC–MS/MS assay of S130 in rat plasma must be necessary. Results: An LC–MS/MS assay for determination of S130 in rat plasma has been first developed and fully verified whose values met the admissible limits as per the US FDA guidelines. Chromatographic separation was achieved by using an isocratic elution after 3 min. MS was conducted under the ESI+ mode fitted with selected reaction monitoring. The calibration curve proved acceptable linearity over 0.50–800 ng/ml. Conclusion: The developed LC–MS/MS assay of S130 in rat plasma is easily applicable in pharmacokinetics study and the further toxicological evaluation.

Dihydropyrimidine Dehydrogenase Levels in Colorectal Cancer Cells Treated with a Combination of Heat Shock Protein 90 Inhibitor and Oxaliplatin or Capecitabine

Purpose: Dihydropyrimidine dehydrogenase (DPD) is the principal enzyme in the catabolism of fluoropyrimidine drugs including capecitabine. A recent report has suggested that oxaliplatin chemotherapy is associated with elevated DPD levels and chemoresistance pattern. As a newly developed chemotherapeutic agent, 17-allyloamino-17-demethoxy-geldanamycin (17-AAG) can be effective in combination therapy with oxaliplatin and capecitabine in colorectal cancer (CRC). DPD expression level can be a predictive factor in oxaliplatin and capecitabine-based chemotherapy. We evaluated DPD in mRNA and protein levels with new treatments: 17-AAG in combination with oxaliplatin and capecitabine in HT-29 and HCT-116 cell lines. Methods: Drug sensitivity was determined by the water-soluble tetrazolium-1 assay in a previous survey. Then, we evaluated the expression levels of DPD and its relationship with the chemotherapy response in capecitabine, oxaliplatin, and 17-AAG treated cases in single and combination cases in two panels of CRC cell lines. DPD gene and protein expression levels were determined by real-time polymerase chain reaction and western blotting assay, respectively. Results: DPD gene expression levels insignificantly increased in single-treated cases versus untreated controls in both cell lines versus controls. Then, the capecitabine and oxaliplatin were added in double combinations, where DPD gene and protein expression increased in combination cases compared to pre-chemotherapy and single drug treatments. Conclusion: The elevated levels of cytotoxicity in more effective combinations could be related to a different mechanism apart from DPD mediating effects or high DPD level in the remaining resistance cells (drug-insensitive cells), which should be investigated in subsequent studies.

Heterogeneous nuclear ribonucleoprotein L facilitates recruitment of 53BP1 and BRCA1 at the DNA break sites induced by oxaliplatin in colorectal cancer

Although oxaliplatin is an effective chemotherapeutic drug for treatment of colorectal cancer (CRC), tumor cells can develop mechanisms to evade oxaliplatin-induced cell death and show high tolerance and acquired resistance to this drug. Heterogeneous nuclear ribonucleoprotein L (hnRNP L) has been proved to play a critical role in DNA repair during IgH class switch recombination (CSR) in B lymphocytes, while, its role in CRC and chemotherapeutic resistance remain unknown. Our study aims to uncover an unidentified mechanism of regulating DNA double-strand breaks (DSBs) by hnRNP L in CRC cells treated by oxaliplatin. In present study, we observed that knockdown of hnRNP L enhanced the level of DNA breakage and sensitivity of CRC cells to oxaliplatin. The expression of key DNA repair factors (BRCA1, 53BP1, and ATM) was unaffected by hnRNP L knockdown, thereby excluding the likelihood of hnRNP L mediation via mRNA regulation. Moreover, we observed that phosphorylation level of ATM changed oppositely to 53BP1 and BRCA1 in the CRC cells (SW620 and HCT116) which exhibit synergistic effect by oxaliplatin plus hnRNP L impairment. And similar phenomenon was observed in the foci formation of these critical repair factors. We also found that hnRNP L binds directly with these DNA repair factors through its RNA-recognition motifs (RRMs). Analysis of cell death indicated that the RRMs of hnRNP L are required for cell survival under incubation with oxaliplatin. In conclusion, hnRNP L is critical for the recruitment of the DNA repair factors in oxaliplatin-induced DSBs. Targeting hnRNP L is a promising new clinical approach that could enhance the effectiveness of current chemotherapeutic treatment in patients with resistance to oxaliplatin.

Novel association between heterozygous genotype of single nucleotide polymorphism C218T in drug transporter ABCC1 gene and increased risk of colon cancer

Objectives:

To determine the role of G128C and C218T variants in ABCC1 gene with the risk of developing colon cancer in Jeddah, Kingdom of Saudi Arabia.

Methods:

This case-control study was conducted on 51 colon cancer patients and 65 controls from King Abdulaziz University Hospital and King Abdullah Medical City in the period from January 2015 to April 2017, and was approved by the Unit of Biomedical Ethics (no: 261-15). Experiments were performed in the experimental biochemistry unit at King Fahd Medical Research Center. The genotype distributions and allele frequencies were determined by polymerase chain reaction-restriction fragments length polymorphism (PCR-RFLP) and DNA sequencing. A Chi-square test was used to determine allele and genotype distributions, odds ratio (OR), risk ratio (RR) and 95% confidence intervals (CI). P-values of <0.05 were considered statistically significant.

Results:

The results showed a novel association between heterozygous (CT) genotype for variant C218T and increased risk of colon cancer [OR=3.4, 95% CI (1.56-7.48), and RR=1.92, 95% CI (1.26-2.93), p=0.002]. These ratios were correlated with high-grade stages (III and IV). In contrast, for variant G128C, there was no significant association with the risk of developing colon cancer.

Conclusion:

The novel findings of the study revealed that the CT genotype of variant C218T in ABCC1 gene may increase the risk of developing colon cancer.

Reversal effect of ginsenoside Rh2 on oxaliplatin-resistant colon cancer cells and its mechanism

Chemotherapy is an important treatment modality for colon cancer, however, drug resistance is the main factor leading to treatment failure. Ginsenoside Rh2 (G-Rh2), the main bioactive metabolite of ginseng, is known to possess the ability to potently induce cell apoptosis, inhibit cell proliferation and reverse multidrug resistance in a variety of cancer cells. The present study examined the effect of G-Rh2 on oxaliplatin (L-OHP)-resistant colon cancer cells and its potential mechanism. L-OHP-resistant colon cancer cells (LoVo/L-OHP) and LoVo cells were used in the present study. The effect of G-Rh2 on LoVo/L-OHP and LoVo cell proliferation was measured using a 3-(4,5 dimethylthiazol-z-yl)-3,5-diphenyltetrazolium bromide assay. The effects of G-Rh2 on LoVo/L-OHP and LoVo cell apoptosis were detected by flow cytometry. The mRNA and protein expression of apoptosis-related genes Bax, Bcl-2 and caspase-3, drug resistance-related genes P-glycoprotein (P-gp) and Smad4, were determined in LoVo/L-OHP and LoVo cells treated with G-Rh2 by reverse transcription-quantitative polymerase chain reaction and western blot analyses. G-Rh2 treatment significantly inhibited the proliferation and induced the apoptosis of LoVo/L-OHP and LoVo cells. In addition, G-Rh2 treatment resulted in a significant increase in pro-apoptotic factors, Bax and caspase-3, and decrease in anti-apoptotic factor Bcl-2 in the LoVo/L-OHP and LoVo cells. Furthermore, G-Rh2 treatment significantly decreased the levels of P-gp and increased the levels of Smad4 in the LoVo/L-OHP and LoVo cells. It was found that L-OHP had no significant effects on LoVo/L-OHP cell proliferation or apoptosis, whereas G-Rh2 + L-OHP treatment significantly inhibited LoVo/L-OHP cell proliferation and induced apoptosis. L-OHP had no significant effects on the expression of P-gp, Smad4, Bcl-2, Bax or caspase-3 in LoVo/L-OHP cells. Treatment with G-Rh2 + L-OHP significantly reduced the expression of P-gp and Bcl-2, and enhanced the expression levels of Smad4, Bax and caspase-3. These findings demonstrated that G-Rh2 reversed the drug resistance of LoVo/L-OHP cells to L-OHP, and this may be mediated by inhibiting cell proliferation and promoting apoptosis and regulating the expression of drug resistance genes. These results suggest that G-Rh2 may function as a potent anticancer drug for drug resistance in colon cancer treatment.

A panel of serum exosomal microRNAs as predictive markers for chemoresistance in advanced colorectal cancer

BACKGROUND

Chemoresistance is a common problem for cancer treatment worldwide. Circulating exosomal microRNAs (miRNAs) have been considered as promising biomarkers of cancers. However, few studies have assessed the relationship between serum/plasma exosomal microRNAs and chemoresistance in colorectal cancer (CRC).

METHODS

Based on previous microarray analysis, we selected 30 miRNAs which are aberrantly expressed during CRC progression and then detected their expression levels in three pairs of oxaliplatin/5-fluorouracil-resistant CRC cell lines and the corresponding secreted exosomes. Six candidate exosomal miRNAs were identified for further evaluating potential value in predicting chemotherapeutic effect in advanced CRC patients. Finally, the molecular mechanisms of these miRNAs in drug resistance were explored by bioinformatics preliminarily.

RESULTS

We observed that the expression of 14 miRNAs was significantly higher in three drug-resistant CRC cells comparing with their parental cells. Among these miRNAs, miR-21-5p, miR-1246, miR-1229-5p, miR-135b, miR-425 and miR-96-5p are also up-regulated in exosomes from culture media of resistant cells. Clinical sample analysis confirmed that the expression levels of miR-21-5p, miR-1246, miR-1229-5p and miR-96-5p in serum exosomes were significantly higher in chemoresistant patients in contrast with chemosensitive controls. ROC curve showed that the combination of the four miRNAs had an area of under the curve (AUC) of 0.804 (P < 0.05). In addition, GO analysis and KEGG pathway analysis revealed that these miRNAs were enriched in PI3K-Akt signaling pathway, FoxO signaling pathway and autophagy pathway.

CONCLUSIONS

Our study demonstrates that a panel of serum exosomal miRNAs containing miR-21-5p, miR-1246, miR-1229-5p and miR-96-5p could significantly distinguish the chemotherapy-resistant group from advanced colorectal cancer patients. Targeting these miRNAs may promote chemosensitivity to oxaliplatin and 5-fluorouracil, and might be promising strategy for CRC treatment.

SSRP1 promotes colorectal cancer progression and is negatively regulated by miR-28-5p

In this study, microarray data analysis, real-time quantitative PCR and immunohistochemistry were used to detect the expression levels of SSRP1 in colorectal cancer (CRC) tissue and in corresponding normal tissue. The association between structure-specific recognition protein 1 (SSRP1) expression and patient prognosis was examined by Kaplan-Meier analysis. SSRP1 was knocked down and overexpressed in CRC cell lines, and its effects on proliferation, cell cycling, migration, invasion, cellular energy metabolism, apoptosis, chemotherapeutic drug sensitivity and cell phenotype-related molecules were assessed. The growth of xenograft tumours in nude mice was also assessed. MiRNAs that potentially targeted SSRP1 were determined by bioinformatic analysis, Western blotting and luciferase reporter assays. We showed that SSRP1 mRNA levels were significantly increased in CRC tissue. We also confirmed that this upregulation was related to the terminal tumour stage in CRC patients, and high expression levels of SSRP1 predicted shorter disease-free survival and faster relapse. We also found that SSRP1 modulated proliferation, metastasis, cellular energy metabolism and the epithelial-mesenchymal transition in CRC. Furthermore, SSRP1 induced apoptosis and SSRP1 knockdown augmented the sensitivity of CRC cells to 5-fluorouracil and cisplatin. Moreover, we explored the molecular mechanisms accounting for the dysregulation of SSRP1 in CRC and identified microRNA-28-5p (miR-28-5p) as a direct upstream regulator of SSRP1. We concluded that SSRP1 promotes CRC progression and is negatively regulated by miR-28-5p.

Curcumin reverses irinotecan resistance in colon cancer cell by regulation of epithelial-mesenchymal transition

The objective of this study was to investigate the effect and the mechanism by which curcumin reverses irinotecan-induced chemotherapy resistance in colon cancer. Construction of irinotecan-resistant colon cancer model LoVo/CPT-11R cells was performed by increasing drug concentration. The Cell Counting Kit-8 assay was used to detect inhibition of proliferation; cell morphology was observed by an optical microscope. Quantitative RT-PCR and western blotting were performed to detect molecular marker expressions during epithelial-mesenchymal transition (EMT); drug-resistant cells were treated with curcumin at different concentrations and Cell Counting Kit-8 was reperformed to detect cell proliferation after treatments. Drug-resistant cells were then divided into four groups: control group, irinotecan group, curcumin group, and irinotecan+curcumin group; quantitative RT-PCR and western blotting were performed to detect molecular marker expressions during epithelial-mesenchymal transition. Flow cytometry was used to detect cell apoptosis after grouping, and apoptosis-related protein was detected by western blotting. LoVo/CPT-11R cells could survive in culture medium containing irinotecan at 60 μg/ml and the drug-resistance index was 5.69; the drug-resistant cells had a larger volume than normal cells and were poorly connected to each other. E-cadherin expression was downregulated, whereas vimentin and N-cadherin expressions were upregulated. After curcumin treatment, drug-resistant cell proliferation was significantly inhibited; in the curcumin+irinotecan treatment group, E-cadherin expression was upregulated, whereas vimentin and N-cadherin expressions were downregulated. Curcumin could significantly increase cell apoptosis. EMT is involved in the development of irinotecan resistance and curcumin can reverse this drug resistance through reversion of the EMT process.

Photodynamic therapy as salvage therapy for residual microscopic cancer after ultra-low anterior resection: A case report

BACKGROUND

The rate of positive resection margins (R1) in patients with low rectal cancer is substantial. Recommended remedies such as extended resection or chemoradiotherapy have their own serious drawbacks. It has been reported that photodynamic therapy (PDT) as a remedial treatment for esophageal cancer. Colorectal cancer and esophageal cancer has many similarities, however, PDT as a salvage therapy for rectal cancer is rare.

CASE SUMMARY

Here, we describe a 56-year-old man who was admitted to the hospital due to a 6-mo history of hemafecia, which had been aggravated for 1 mo. Colonoscopy revealed a 3 × 4 cm ulcerated mass in the rectum 4 cm from the anus. Preoperative pathological examination showed villous adenoma, moderate-to-high-grade dysplasia, good differentiation, and invasion of the mucosal muscle. The patient had R1 after ultra-low anterior resection, but he refused extended resection and experienced severe liver function impairment after 3 cycles of chemotherapy. Ultimately, the patient underwent PDT to remove R1. After five years of follow-up, there was no liver function impairment, recurrence, metastasis, sexual dysfunction, or abnormal defecation function.

CONCLUSION

This is the first case worldwide in which R1 of rectal cancer were successfully treated by PDT.

Phase I study of preoperative chemoradiotherapy with sequential oxaliplatin and irinotecan with S-1 for locally advanced rectal cancer

The present study designed a novel preoperative chemoradiotherapy (CRT) with sequential oxaliplatin and irinotecan with S-1 for locally advanced rectal cancer (LARC). This phase I study evaluated the maximum tolerated dose and recommended dose (RD) of oxaliplatin following irinotecan with S-1. Patients with clinical stage T3 or 4 or involvement of the regional nodes and no evidence of distant metastases were treated with fixed doses of S-1 (80 mg/m²/day) on days 1-5, 8-12, 15-19, 22-27 and 29-33, and irinotecan (40 mg/m²/day) on days 1 and 8, followed by oxaliplatin on days 22 and 29. The dose of oxaliplatin was initially 40 mg/m² (level 1) with a predefined dose escalation schedule. The radiation dose was 1.8 Gy/fraction to a total dose of 45 Gy. A total of 9 patients were enrolled in the present study and 7 patients completely received CRT with this study protocol. The maximum tolerated dose for oxaliplatin was 50 mg/m² (level 2). Three of four patients experienced dose-limiting toxicity (grade 3 diarrhea) in oxaliplatin phase of level 2 dose. The RD of oxaliplatin was 40 mg/m² (level 1 dose). In addition, 2 patients had pathological CR (28.5%). Novel preoperative CRT with sequential oxaliplatin and irinotecan with S-1 for LARC resulted in acceptable toxicity and promising efficacy. However, the RD of oxaliplatin was lower than in previous CRT studies that combined oxaliplatin with S-1. To administer higher oxaliplatin, we have planned a phase I trial of preoperative CRT with sequential oxaliplatin followed by irinotecan with S-1 for LARC.

Evaluation of the two polymorphisms rs1801133 in MTHFR and rs10811661 in CDKN2A/B in breast cancer

The 5,10-Methylenetetrahydrofolate reductase (MTHFR) was the rate-limiting enzyme in the methyl cycle, which was encoded by the MTHFR gene. MTHFR played a key role in homocysteine plasma level and was associated with the risk of breast cancer. The cyclin-dependent kinase (CDK) inhibitor (CDKN2A/B) was the tumor suppressor in the cell cycle regulation. The single-nucleotide polymorphism was thought to be associated with the predisposition of breast cancer and in subsequent immune response in different populations. The current study was conducted on a peripheral blood sample of 100 Iranian women with breast carcinoma and 142 cancer-free healthy female volunteers. The TaqMan real-time polymerase chain reaction technique was applied for genotyping of participants. The correlation of both variants and demographic data were investigated with the risk of breast cancer. Our data showed that the MTHFR allele T and TT genotype had the higher prevalence in patients (P < 0.0001) than the control group. The frequency of risk C allele into the CDKN2A/B rs10811661 was 72%. The correlations of menarche and underlying hormonal disorder with the risk of breast cancer were investigated; also our results showed that the menopause status was statistically significant between patients and controls (P = 0.036). Our investigations demonstrated that the MTHFR rs180113 and CDKN2A/B rs10811661 had a significant correlation with the elevated risk of breast cancer and they might be potentially valuable to apply as a prognostic factor for individual health care.

MiR-26b regulates 5-FU-resistance in human colorectal cancer via down-regulation of Pgp

Chemotherapy resistance frequently drives tumor progression. However, the underlying molecular mechanisms remain unclear. In this study, we found that the expression level of miR-26b was down-regulated in the human colorectal cancer tissues and the resistant cells strains: HT-29/5-FU and LOVO/5-FU cells. Meanwhile, we showed that miR-26b improved sensibility of colorectal cancer cells to 5-FU in vitro and enhanced the potency of 5-FU in the inhibition of tumor growth in vivo. We further demonstrated that the tumor suppressive role of miR-26b was mediated by negatively regulating P-glycoprotein (Pgp) protein expression. Furthermore, studies of colorectal cancer specimens indicated that the expression of miR-26b and Pgp had inverse correlation. Importantly, we found that CpG islands in the miR-26b promoter region were hypermethylated in 5-FU resistant cells. Our study is the first to identify the tumor suppressive role of over-expressed miR-26b in chemo-sensitivity. Identification of a novel miRNA-mediated pathway that regulates chemo-sensitivity in colorectal cancer will facilitate the development of novel therapeutic strategies in the future.

Intestinal helminths and protozoan infections in patients with colorectal cancer: prevalence and possible association with cancer pathogenesis

The purpose of the present study was to determine the prevalence of intestinal helminths and protozoa in colorectal cancer (CRC) patients and to evaluate the possible association between the prevalence and CRC pathogenesis. A total of 200 CRC patients and 200 residents of Tashkent, who had no complaints related to the gastrointestinal tract, were examined by triple coproscopy using a concentration method and estimations of protozoan infection intensity. Of the CRC patients tested, 144 were classified as T₁-₄N₀M₀ (without metastases) and 56 were classified as T_1-4N_1-2M_0-1 (with metastases). Parasitological examination was performed during CRC diagnosis before and after surgery and chemotherapy. A significantly higher prevalence of Blastocystis sp., Chilomastix mesnili, Jodamoeba butschlii, and Endolimax nana was found in CRC patients than in the control population (p < 0.0001), amounting to 80, 20, 22.5, and 11.5%, respectively. The high prevalence of Blastocystis sp., as well as the patterns of infection intensity, was stable at all stages of examination. The ratio of the number of CRC patients with and without Blastocystis sp. in the T_1-4N₀M₀ and T_1-4N_1-2M_0-1 groups amounted to 3.3 and 7.0, respectively. The ratios for C. mesnili, E. coli, J. butschlii, and E. nana in both groups were 0.2 and 0.2, 0.07 and 0.07, 0.3 and 0.16, and 0.18 and 0.01, respectively. The prevalence of helminths and Giardia lamblia in CRC patients and the control population was not significantly different. Taken together, these data indicate a possible role for Blastocystis sp. in CRC pathogenesis. Diagnosis, treatment, and further observation of patients with Blastocystis sp. are necessary at all stages of CRC, including during diagnosis and before and after surgery and chemotherapy.

Combination of resveratrol and 5-flurouracil enhanced anti-telomerase activity and apoptosis by inhibiting STAT3 and Akt signaling pathways in human colorectal cancer cells

Colorectal cancer is one of the leading causes for mortalities worldwide. The most common cause of colorectal cancer mortality is hepatic metastasis. There has been a limited advancement in the targeted-therapies for metastatic colorectal cancer. Conventional chemotherapeutic agent 5-fluorouracil has been used for various cancer treatments including colorectal cancer. Development of drug resistance and severe toxicity are major hurdles for its use in clinical setting. Resveratrol is a natural polyphenolic compound which has protective effects against aging-related diseases. In this study, we have tested whether combined treatments of resveratrol and 5-FU enhanced inhibitory effects against colorectal cancer cell growth. We herein showed that resveratrol and 5-FU combination treatments caused the anti-cancer activities by simultaneously inhibiting STAT3 and Akt signaling pathways. Resveratrol treatment induced S-phase specific cell cycle arrest, and when combined with 5-FU, it showed further increase in colorectal cancer cell apoptosis. Combined treatments of resveratrol and 5-FU inhibited epithelial-mesenchymal transition. Notably, resveratrol showed anti-inflammatory effects by downregulating inflammatory biomarkers, pSTAT3 and pNFκB. Resveratrol and 5-FU treatments inhibited STAT3 phosphorylation and its binding to the promoter region of human telomerase reverse transcriptase (hTERT). Our data provide the first evidence that resveratrol can enhance anti-telomeric and pro-apoptotic potentials of 5-FU in colorectal cancer, hence lead to re-sensitization to chemotherapy.

miRNAs and lncRNAs as Predictive Biomarkers of Response to FOLFOX Therapy in Colorectal Cancer

Chemotherapy is one of the options for cancer treatment. FOLFOX is one of the widely used chemotherapeutic regimens used to treat primarily colorectal cancer and other cancers as well. However, the emergence of chemo-resistance clones during cancer treatment has become a critical challenge in the clinical setting. It is crucial to identify the potential biomarkers and therapeutics targets which could lead to an improvement in the success rate of the proposed therapies. Since non-coding RNAs have been known to be important players in the cellular system, the interest in their functional roles has intensified. Non-coding RNAs (ncRNAs) as regulators at the post-transcriptional level could be very promising to provide insights in overcoming chemo-resistance to FOLFOX. Hence, this mini review attempts to summarize the potential of ncRNAs correlating with chemo-sensitivity/resistance to FOLFOX.

Host genetic profiling to increase drug safety in colorectal cancer from discovery to implementation

Adverse events affect the pharmacological treatment of approximately 90% of colorectal cancer (CRC) patients at any stage of the disease. Chemotherapy including fluoropyrimidines, irinotecan, and oxaliplatin is the cornerstone of the pharmacological treatment of CRC. The introduction of novel targeted agents, as anti-EGFR (i.e. cetuximab, panitumumab) and antiangiogenic (i.e. bevacizumab, ziv-aflibercept, regorafenib, and ramucirumab) molecules, into the oncologist's toolbox has led to significant improvements in the life expectancy of advanced CRC patients, but with a substantial increase in toxicity burden. In this respect, pharmacogenomics has largely been applied to the personalization of CRC chemotherapy, focusing mainly on the study of inhered polymorphisms in genes encoding phase I and II enzymes, ATP-binding cassette (ABC)/solute carrier (SLC) membrane transporters, proteins involved in DNA repair, folate pathway and immune response. These research efforts have led to the identification of some validated genetic markers of chemotherapy toxicity, for fluoropyrimidines and irinotecan. No validated genetic determinants of oxaliplatin-specific toxicity, as peripheral neuropathy, has thus far been established. The contribution of host genetic markers in predicting the toxicity associated with novel targeted agents' administration is still controversial due to the heterogeneity of published data. Pharmacogenomics guidelines have been published by some international scientific consortia such as the Clinical Pharmacogenomics Implementation Consortium (CPIC) and the Dutch Pharmacogenetics Working Group (DPWG) strongly suggesting a pre-treatment dose adjustment of irinotecan based on UGT1A1*28 genotype and of fluoropyrimidines based on some DPYD genetic variants, to increase treatment safety. However, these recommendations are still poorly applied at the patient's bedside. Several ongoing projects in the U.S. and Europe are currently evaluating how pharmacogenomics can be implemented successfully in daily clinical practice. The majority of drug-related adverse events are still unexplained, and a great deal of ongoing research is aimed at improving knowledge of the role of pharmacogenomics in increasing treatment safety. In this review, the issue of pre-treatment identification of CRC patients at risk of toxicity via the analysis of patients' genetic profiles is addressed. Available pharmacogenomics guidelines with ongoing efforts to implement them in clinical practice and new exploratory markers for clinical validation are described.

PIK3CA mutations confer resistance to first-line chemotherapy in colorectal cancer

Chemotherapy represents an important treatment option for colorectal cancer (CRC), but only half of the patients benefit from these regimens. We explored the potential predicting value and mechanism of PIK3CA mutation in CRC chemotherapy. CRC specimens from 440 patients were retrospectively collected and examined with a fluorescence PCR-based method. The correlation of first-line chemotherapy response and PIK3CA mutation was evaluated according to follow-up and medical records. The underlying mechanism of PIK3CA mutation in chemotherapy resistance was assessed with CRC tumors and primary cells. The mutation frequency of the PIK3CA gene in CRC patients was 9.55%, which was correlated with late TNM staging and lower histological grade. The CRC patients with PIK3A mutation showed worse response to first-line chemotherapy than those without PIK3CA mutation. PIK3A mutation tumor cells showed poor sensitivity to first-line chemotherapy in vitro and in vivo. PIK3CA mutation induced PI3K/Akt signaling activation to increase LGR5⁺ CRC stem cells survival and proliferation, from which lead to chemotherapy resistance. Furthermore, PIK3CA^mutation/LGR5⁺ expression was an independent detrimental factor for CRC patients. Our findings indicated that PIK3CA mutation induced PI3K/Akt activation contributed to CRC stem cells survival and proliferation, from which cells further resistance to chemotherapy. PIK3CA ^mutation/LGR5⁺ expression was a potential biomarker for monitoring chemotherapy resistance in CRC.

Iron chelation inhibits cancer cell growth and modulates global histone methylation status in colorectal cancer

Colorectal cancer (CRC) is one of the most common malignancies worldwide, and new treatment strategies for CRC are required because of the existing chemotherapy resistance. Iron chelators, which have been used widely for the treatment of iron-overload disease, were reported to exert anti-proliferative effects in cancer. However, the role of iron chelation in CRC was largely unknown. In this study, we found that the iron chelator DFO inhibited CRC cell growth significantly. In addition, the gene expression profile was greatly changed by DFO treatment, and many cell growth-related genes were dysregulated. Further study showed that DFO induced a significant increase in global histone methylation in CRC cells. However, the levels of histone methyltransferases and histone demethylases did not change in response to DFO treatment, implying that the enzymatic activity of these enzymes might be regulated by iron chelation. In conclusion, this study reveals a novel role for DFO in CRC cell growth, and is the first to demonstrate that global histone methylation is modulated by iron chelation in CRC cells.

Pharmacogenetics and Pharmacogenomics of Targeted Therapeutics in Chronic Myeloid Leukemia

The advent of targeted therapeutics has greatly improved outcomes of chronic myeloid leukemia (CML) patients. Despite increased efficacy and better clinical responses over cytotoxic chemotherapies, many patients receiving targeted drugs exhibit a poor initial response, develop drug resistance, or undergo relapse after initial success. This inter-individual variation in response has heightened the interest in studying pharmacogenetics and pharmacogenomics (PGx) of cancer drugs. In this review, we discuss the influence of various germline and somatic factors on targeted drug response in CML. Specifically, we examine the role of genetic variants in drug metabolism genes, i.e. CYP3A family genes, and drug transporters, i.e. ABC and SLC family genes. Additionally, we focus on acquired somatic variations in BCR-ABL1, and the potential role played by additional downstream signaling pathways, in conferring resistance to targeted drugs in CML. This review highlights the importance of PGx of targeted therapeutics and its potential application to improving treatment decisions and patient outcomes.

The cyclohexene derivative MC-3129 exhibits antileukemic activity via RhoA/ROCK1/PTEN/PI3K/Akt pathway-mediated mitochondrial translocation of cofilin

The effects of MC-3129, a synthetic cyclohexene derivative, on cell viability and apoptosis have been investigated in human leukemia cells. Exposure of leukemia cells to MC-3129 led to the inhibition of cell viability and induction of apoptosis through the dephosphorylation and mitochondrial translocation of cofilin. A mechanistic study revealed that interruption of the RhoA/ROCK1/PTEN/PI3K/Akt signaling pathway plays a crucial role in the MC-3129-mediated dephosphorylation and mitochondrial translocation of cofilin and induction of apoptosis. Our in vivo study also showed that the MC-3129-mediated inhibition of the tumor growth in a mouse leukemia xenograft model is associated with the interruption of ROCK1/PTEN/PI3K/Akt signaling and apoptosis. Molecular docking suggested that MC-3129 might activate the RhoA/ROCK1 pathway by targeting LPAR2. Collectively, these findings suggest a hierarchical model, in which the induction of apoptosis by MC-3129 primarily results from the activation of RhoA/ROCK1/PTEN and inactivation of PI3K/Akt, leading to the dephosphorylation and mitochondrial translocation of cofilin, and culminating in cytochrome c release, caspase activation, and apoptosis. Our study reveals a novel role for RhoA/ROCK1/PTEN/PI3K/Akt signaling in the regulation of mitochondrial translocation of cofilin and apoptosis and suggests MC-3129 as a potential drug for the treatment of human leukemia.

SNPs in predicting clinical efficacy and toxicity of chemotherapy: walking through the quicksand

In the "precision medicine" era, chemotherapy still remains the backbone for the treatment of many cancers, but no affordable predictors of response to the chemodrugs are available in clinical practice. Single nucleotide polymorphisms (SNPs) are gene sequence variations occurring in more than 1% of the full population, and account for approximately 80% of inter-individual genomic heterogeneity. A number of studies have investigated the predictive role of SNPs of genes enrolled in both pharmacodynamics and pharmacokinetics of chemotherapeutics, but the clinical implementation of related results has been modest so far. Among the examined germline polymorphic variants, several SNPs of dihydropyrimidine dehydrogenase (DPYD) and uridine diphosphate glucuronosyltransferases (UGT) have shown a robust role as predictors of toxicity following fluoropyrimidine- and/or irinotecan-based treatments respectively, and a few guidelines are mandatory in their detection before therapy initiation. Contrasting results, however, have been reported on the capability of variants of other genes as MTHFR, TYMS, ERCC1, XRCC1, GSTP1, CYP3A4/3A5 and ABCB1, in predicting either therapy efficacy or toxicity in patients undergoing treatment with pyrimidine antimetabolites, platinum derivatives, irinotecan and taxanes. While formal recommendations for routine testing of these SNPs cannot be drawn at this moment, therapeutic decisions may indeed benefit of germline genomic information, when available. Here, we summarize the clinical impact of germline genomic variants on the efficacy and toxicity of major chemodrugs, with the aim to facilitate the therapeutic expectance of clinicians in the odiern quicksand field of complex molecular biology concepts and controversial trial data interpretation.

Butyrate, a dietary fiber derivative that improves irinotecan effect in colon cancer cells

A diet rich in fiber is associated with a low risk of developing colorectal cancer. Dietary fiber fermentation by intestinal microflora results in the production of butyrate, which has been reported as a chemopreventive agent and a histone deacetylase inhibitor (HDACi). Irinotecan is used as second-line treatment and induces adverse effects with serious life-threatening toxicities in at least 36% of patients. Our study intends to find a synergy that could improve the efficacy and decrease the toxicity of chemotherapy. Results demonstrate that milimolar concentrations of butyrate has an anti-proliferative effect in all three colon cancer cell lines under study, leading to a decrease on cell viability, expression of P21, P53 and β-catenin, being able to modulate P-glycoprotein activity and to induce apoptosis by modulation of BAX/BCL-2 ratio. Combined therapy has a cytotoxic potential, resulting in a synergistic effect, and allows a reduction in irinotecan concentration needed to reduce IC₅₀. This potential was verified in terms of cell viability and death, cell cycle and expression of P21 and P53. Butyrate and irinotecan act synergistically in the three cancer cell lines, despite the different genetic background and location, and inhibited tumor growth in a xenograft model. Butyrate is able to influence the mechanism of LS1034 cell line chemoresistance. Butyrate in combination with chemotherapeutic agents has an important role for the treatment of colorectal cancer. Such understanding can guide decisions about which patients with colorectal cancer may benefit from therapy with butyrate demonstrating the important role of diet in colorectal cancer treatment.

The Role of Fluoropirimidines in Gastrointestinal Tumours: from the Bench to the Bed

PURPOSE

Gastrointestinal tumours are one of the most common types of cancer. Therapeutic options include surgery, radiotherapy, local ablation techniques, targeted agents, and chemotherapy. Fluoroprimidines are one of the most active drug families in digestive tumours and remains the cornerstone of the most commonly used chemotherapy schemes.

METHODS

We review the molecular basis of thymidylate synthase inhibition and the mechanisms of action of 5-fluorouracil, next generation oral fluoropyrimidines (capecitabine, tegafur and the latest S-1 and TAS-102) and antifolates.

RESULTS

In addition, mechanisms and biomarkers of resistance and toxicity are explored. Finally, new fluoropyrimidines development and clinical trials ongoing in digestive tumours are reviewed.

CONCLUSIONS

Further research is necessary to avoid resistance mechanisms, improve clinical outcomes and continue reducing toxicities. Until new drugs become available, the optimization of current therapies should be a priority.

Pharmacogenetics of toxicity of 5-fluorouracil, doxorubicin and cyclophosphamide chemotherapy in breast cancer patients

The differences in patients' response to the same medication, toxicity included, are one of the major problems in breast cancer treatment. Chemotherapy toxicity makes a significant clinical problem due to decreased quality of life, prolongation of treatment and reinforcement of negative emotions associated with therapy. In this study we evaluated the genetic and clinical risk factors of FAC chemotherapy-related toxicities in the group of 324 breast cancer patients. Selected genes and their polymorphisms were involved in FAC drugs transport (ABCB1, ABCC2, ABCG2,SLC22A16), metabolism (ALDH3A1, CBR1, CYP1B1, CYP2C19, DPYD, GSTM1, GSTP1, GSTT1, MTHFR,TYMS), DNA damage recognition, repair and cell cycle control (ATM, ERCC1, ERCC2, TP53, XRCC1). The multifactorial risk models that combine genetic risk modifiers and clinical characteristics were constructed for 12 toxic symptoms. The majority of toxicities was dependent on the modifications in components of more than one pathway of FAC drugs, while the impact level of clinical factors was comparable to the genetic ones. For the carriers of multiple high risk factors the chance of developing given symptom was significantly elevated which proved the factor-dosage effect. We found the strongest associations between concurrent presence of clinical factors - overall and recurrent anemia, nephrotoxicity and early nausea and genetic polymorphisms in genes responsible for DNA repair, drugs metabolism and transport pathways. These results indicate the possibility of selection of the patients with expected high tolerance to FAC treatment and consequently with high chance of chemotherapy completion without the dose reduction, treatment delays and decline in the quality of life.

ABCC2-24C > T polymorphism is associated with the response to platinum/5-Fu-based neoadjuvant chemotherapy and better clinical outcomes in advanced gastric cancer patients

Several studies have evaluated the efficacy of neoadjuvant treatment using oxaliplatin and fluoropyrimidines in advanced gastric cancer (GC). However, preoperative biomarkers predictive of clinical outcome remain lacking. We examined polymorphisms in the MTHFR, DPYD, UMPS, ABCB1, ABCC2, GSTP1, ERCC1, and XRCC1 genes to evaluate their usefulness as pharmacogenetic markers in a cohort of 103 GC patients treated with preoperative chemotherapy. DNA was extracted from peripheral blood cells, and the genotypes were analyzed using a SNaPShot^TM assay, polymerase chain reaction amplification, and sequencing. The ABCC2-24C > T (rs717620) genotype was associated with pathologic response to neoadjuvant chemotherapy. Patients with the TT and TC genotypes responded to neoadjuvant chemotherapy 3.80 times more often than those with the CC genotype (95% CI: 1.27–11.32). Patients with the CC genotype also had poorer outcomes than those with other genotypes. Thus, ABCC2-24C > T polymorphism may help to predict the response to preoperative chemotherapy in GC patients.

Baicalein and baicalin inhibit colon cancer using two distinct fashions of apoptosis and senescence

Baicalein and baicalin are active components of the Scutellaria baicalensis Georgi and both have broad anti-tumor activity. However, how and whether baicalein and baicalin inhibit colon cancer is unclear. Here we demonstrate that baicalein and baicalin can significantly inhibit human colon cancer cell growth and proliferation. Furthermore, both can induce cell cycle arrest, and suppress cancer cell colony formation and migration. The suppressive effects are mechanistically due to the induction of colon cancer cell apoptosis and senescence mediated by baicalein and baicalin, respectively. Furthermore, we revealed that baicalin-induced senescence in tumor cells is due to its inhibition of telomerase reverse transcriptase expression in tumor cells, and that MAPK ERK and p38 signaling pathways are causatively involved in the regulation of colon cancer cell apoptosis and senescence mediated by baicalein and baicalin. In addition, our in vivo studies using human colon cancer cells in humanized mouse xenograft models, further demonstrated that baicalein and baicalin can induce tumor cell apoptosis and senescence, resulting in inhibition of tumorigenesis and growth of colon cancer in vivo. These data clearly suggest that baicalein and baicalin have potent anti-cancer effects against human colon cancer and could be potential novel and effective target drugs for cancer therapy.

Clinical study of ultrasound and microbubbles for enhancing chemotherapeutic sensitivity of malignant tumors in digestive system

Objective

To explore the safety of ultrasound and microbubbles for enhancing the chemotherapeutic sensitivity of malignant tumors in the digestive system in a clinical trial, as well as its efficacy.

Methods

From October 2014 to June 2016, twelve patients volunteered to participate in this study. Eleven patients had hepatic metastases from tumors of the digestive system, and one patient had pancreatic carcinoma. According to the mechanical index (MI) in the ultrasound field, patients were classified into four groups with MIs of 0.4, 0.6, 0.8 and 1.0. Within half an hour after chemotherapy, patients underwent ultrasound scanning with ultrasound microbubbles (SonoVue) to enhance the efficacy of chemotherapy. All adverse reactions were recorded and were classified in 4 grades according to the Common Terminology Criteria for Adverse Events version 4.03 (CTCAE V4.03). Tumor responses were evaluated by the Response Evaluation Criteria in Solid Tumors version 1.1 criteria. All the patients were followed up until progression.

Results

All the adverse reactions recorded were level 1 or level 2. No local pain occurred in any of the patients. Among all the adverse reactions, fever might be related to the treatment with ultrasound combined with microbubbles. Six patients had stable disease (SD), and one patient had a partial response (PR) after the first cycle of treatment. At the end of follow-up, tumor progression was restricted to the original sites, and no new lesions had appeared.

Conclusions

Our preliminary data showed the potential role of a combined treatment with ultrasound and microbubbles in enhancing the chemotherapeutic sensitivity of malignant tumors of the digestive system. This technique is safe when the MI is no greater than 1.0.

Effect of AICAR and 5-Fluorouracil on X-ray Repair, Cross-Complementing Group 1 Expression, and Consequent Cytotoxicity Regulation in Human HCT-116 Colorectal Cancer Cells

Colorectal cancer (CRC) is one of the leading causes of cancer mortality and 5-Fluorouracil (5-FU) is the most common chemotherapy agent of CRC. A high level of X-ray repair cross complementing group 1 (XRCC1) in cancer cells has been associated with the drug resistance occurrence. Moreover, the activation of adenosine monophosphate (AMP)-activated protein kinase (AMPK) has been indicated to regulate the cancer cell survival. Thus, this study was aimed to examine whether XRCC1 plays a role in the 5-FU/AMPK agonist (AICAR)-induced cytotoxic effect on CRC and the underlying mechanisms. Human HCT-116 colorectal cells were used in this study. It was shown that 5-FU increases the XRCC1 expression in HCT-116 cells and then affects the cell survival through CXCR4/Akt signaling. Moreover, 5-FU combined with AICAR further result in more survival inhibition in HCT-116 cells, accompanied with reduced CXCR4/Akt signaling activity and XRCC1 expression. These results elucidate the role and mechanism of XRCC1 in the drug resistance of HCT-116 cells to 5-FU. We also demonstrate the synergistic inhibitory effect of AMPK on 5-FU-inhibited HCT-116 cell survival under the 5-FU and AICAR co-treatment. Thus, our findings may provide a new notion for the future drug regimen incorporating 5-FU and AMPK agonists for the CRC treatment.

Upregulation of miR-146a increases cisplatin sensitivity of the non-small cell lung cancer A549 cell line by targeting JNK-2

The aim of the present study was to investigate the effects of microRNA (miR-)146a on the cisplatin sensitivity of the non-small cell lung cancer (NSCLC) A549 cell line and study the underlying molecular mechanism. The differences in expression of miRNAs between A549 and A549/cisplatin (A549/DDP) cells were determined, and miR-146a was selected to study its effect on cisplatin sensitivity of A549/DDP cells. miR-146a mimic and inhibitor transient transfection systems were constructed using vectors, and A549/DDP cells were infected with miR-146a mimic and inhibitor to investigate growth, apoptosis and migration. The directed target of miR-146a was determined and the underlying molecular mechanism was validated in the present study. The results of the present study demonstrated that miR-146a was downregulated in NSCLC A549/DDP cells, compared with A549 cells. The overexpression of miR-146a induced apoptosis and inhibited the growth and invasion of A549/DDP cells, which resulted in increased cisplatin sensitivity in NSCLC cells. The JNK2 gene was determined as the direct target of miR-146a, and may be activated by the overexpression of miR-146a. Additionally, JNK2 activated the expression of p53 and inhibited B cell lymphoma 2. The upregulation of miR-146a increased cisplatin sensitivity of the A549 cell line by targeting JNK2, which may provide a novel method for treating NSCLC cisplatin resistance.

P53 represses pyrimidine catabolic gene dihydropyrimidine dehydrogenase (DPYD) expression in response to thymidylate synthase (TS) targeting

Nucleotide metabolism in cancer cells can influence malignant behavior and intrinsic resistance to therapy. Here we describe p53-dependent control of the rate-limiting enzyme in the pyrimidine catabolic pathway, dihydropyrimidine dehydrogenase (DPYD) and its effect on pharmacokinetics of and response to 5-fluorouracil (5-FU). Using in silico/chromatin-immunoprecipitation (ChIP) analysis we identify a conserved p53 DNA-binding site (p53BS) downstream of the DPYD gene with increased p53 occupancy following 5-FU treatment of cells. Consequently, decrease in Histone H3K9AC and increase in H3K27me3 marks at the DPYD promoter are observed concomitantly with reduced expression of DPYD mRNA and protein in a p53-dependent manner. Mechanistic studies reveal inhibition of DPYD expression by p53 is augmented following thymidylate synthase (TS) inhibition and DPYD repression by p53 is dependent on DNA-dependent protein kinase (DNA-PK) and Ataxia telangiectasia mutated (ATM) signaling. In-vivo, liver specific Tp53 loss increases the conversion of 5-FU to 5-FUH₂ in plasma and elicits a diminished 5-FU therapeutic response in a syngeneic colorectal tumor model consistent with increased DPYD-activity. Our data suggest that p53 plays an important role in controlling pyrimidine catabolism through repression of DPYD expression, following metabolic stress imposed by nucleotide imbalance. These findings have implications for the toxicity and efficacy of the cancer therapeutic 5-FU.

Integrating TYMS, KRAS and BRAF testing in patients with metastatic colorectal cancer

AIM

To investigate the impact of thymidylate synthase (TYMS), KRAS and BRAF in the survival of metastatic colorectal cancer (mCRC) patients treated with chemotherapy.

METHODS

Clinical data were collected retrospectively from records of consecutive patients with mCRC treated with fluoropyrimidine-based chemotherapy from 1/2005 to 1/2007. Formalin-fixed paraffin-embedded tissues were retrieved for analysis. TYMS genotypes were identified with restriction fragment analysis PCR, while KRAS and BRAF mutation status was evaluated using real-time PCR assays. TYMS gene polymorphisms of each of the 3’ untranslated region (UTR) and 5’UTR were classified into three groups according to the probability they have for high, medium and low TYMS expression (and similar levels of risk) based on evidence from previous studies. Univariate and multivariate survival analyses were performed.

RESULTS

The analysis recovered 89 patients with mCRC (46.1% de novo metastatic disease and 53.9% relapsed). Of these, 46 patients (51.7%) had colon cancer and 43 (48.3%) rectal cancer as primary. All patients were treated with fluoropyrimidine-based chemotherapy (5FU or capecitabine) as single-agent or in combination with irinotecan or/and oxaliplatin or/and bevacizumab. With a median follow-up time of 14.8 mo (range 0-119.8), 85 patients (95.5%) experienced disease progression, and 63 deaths (70.8%) were recorded. The 3-year and 5-year OS rate was 25.4% and 7.7% while the 3-year progression-free survival rate was 7.1%. Multivariate analysis of TYMS polymorphisms, KRAS and BRAF with clinicopathological parameters indicated that TYMS 3’UTR polymorphisms are associated with risk for disease progression and death (P < 0.05 and P < 0.03 respectively). When compared to tumors without any del allele (genotypes ins/ins and ins/loss of heterozygosity (LOH) linked with high TYMS expression) tumors with del/del genotype (low expression group) and tumors with ins/del or del/LOH (intermediate expression group) have lower risk for disease progression (HR = 0.432, 95%CI: 0.198-0.946, P < 0.04 and HR = 0.513, 95%CI: 0.287-0.919, P < 0.03 respectively) and death (HR = 0.366, 95%CI: 0.162-0.827, P < 0.02 and HR = 0.559, 95%CI: 0.309-1.113, P < 0.06 respectively). Additionally, KRAS mutation was associated independently with the risk of disease progression (HR = 1.600, 95%CI: 1.011-2.531, P < 0.05). The addition of irinotecan in 1^st line chemotherapy was associated independently with lower risk for disease progression and death (HR = 0.600, 95%CI: 0.372-0.969, P < 0.04 and HR = 0.352, 95%CI: 0.164-0.757, P < 0.01 respectively).

CONCLUSION

The TYMS genotypes ins/ins and ins/LOH associate with worst prognosis in mCRC patients under fluoropyrimidine-based chemotherapy. Large prospective studies are needed for validation of our findings.

lncRNA HOTAIR Contributes to 5FU Resistance through Suppressing miR-218 and Activating NF-κB/TS Signaling in Colorectal Cancer

One major reason for the failure of advanced colorectal cancer (CRC) treatment is the occurrence of chemoresistance to fluoropyrimidine (FU)-based chemotherapy. Long non-coding RNA HOTAIR has been considered as a pro-oncogene in multiple cancers. However, the precise functional mechanism of HOTAIR in chemoresistance is not well known. In this study, we investigated the biological and clinical role of HOTAIR in 5FU resistance in CRC. Our results showed that HOTAIR negatively regulated miR-218 expression in CRC through an EZH2-targeting miR-218-2 promoter regulatory axis. HOTAIR knockdown dramatically inhibited cell viability and induced G1-phase arrest by promoting miR-218 expression. VOPP1 was shown to be a functional target of miR-218, and the main downstream signaling, NF-κB, was inactivated by HOTAIR through the suppression of miR-218 expression. Additionally, HOTAIR knockdown partially reversed 5FU resistance through promoting miR-218 and inactivating NF-κB signaling. Furthermore, HOTAIR restrained 5FU-induced cytotoxicity on CRC cells through promotion of thymidylate synthase expression. More importantly, high HOTAIR expression was associated with poor response to 5FU treatment. In conclusion, we demonstrated that HOTAIR contributes to 5FU resistance through suppressing miR-218 and activating NF-κB signaling in CRC. Thus, HOTAIR may serve as a promising therapeutic target for CRC patients.

Epithelial-mesenchymal transition and cancer stem cell-like phenotype induced by Twist1 contribute to acquired resistance to irinotecan in colon cancer

Inherent and acquired chemoresistance reduce the effectiveness of irinotecan in the treatment of metastatic colorectal cancer (CRC). However, the molecular mechanisms underlying this resistance process are still unclear. Twist1 is one of the master transcription factors of epithelial-mesenchymal transition (EMT). Our previous study indicated that Twist1 is overexpressed in colon cancer tissues, and demonstrated that Twist1 plays a crucial role in the chemoresistance of CRC. In the present study, we further investigated how Twist1 contribute to acquired resistance to irinotecan in colon cancer. The irinotecan-resistant cells were established by gradual adaptation of increasing irinotecan concentrations in LoVo cells, named LoVo/CPT-11R cells. Results showed that cell viabilities to different anticancer drugs were markedly increased in LoVo/CPT-11R cells compared to LoVo cells. Moreover, LoVo/CPT-11R cells displayed EMT, CSC-like cellular morphology and relative biomarkers were also significantly increased. In addition, overexpressed Twist1 LoVo cells were established by lentivirus transfection assay, named LoVo/Twist1 cells. Results showed that the LoVo/Twist1 cells perform a distinctly decreased sensitivity to irinotecan, downregulated expression of E-cadherin, upregulated expression of cluster of differentiation 44 (CD44), and a significant enhancement of invasion and migration potential by regulation of MMP2 compared with control cells. In contrast, the inhibition of Twist1 transfected with siRNA could enhance the irinotecan sensitivity in LoVo/CPT-11R cells and downregulate the expression of vimentin and CD44. Our data provide evidence that EMT and CSC-like phenotype induced by Twist1 contribute to acquire resistance to irinotecan and enhanced migration and invasion in colon cancer.

Metformin inhibited esophageal squamous cell carcinoma proliferation in vitro and in vivo and enhanced the anti-cancer effect of cisplatin

Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy with poor prognosis in China. Chemotherapy now is one of the most frequently used treatments for patients with ESCC in middle or late stage, however the effects were often limited by increased chemoresistance or treatment toxicity. So it is urgent to find new drugs to treat ESCC patients. Metformin with low cost and toxicity has proved to have anti-cancer effects in a numerous cancers, while its role and mechanism in ESCC has seldom been studied. In the present study, we found that metformin exhibited not only an anti-proliferation ability in a dose and time dependent manner but also a proapoptosis effect in a dose dependent manner in ESCC cell line KYSE450. Our in vivo experiment also showed that metformin markedly inhibited KYSE450 xenograft tumors growth compared to those treated with normal saline. What’s more, no obvious toxic reactions were observed. To further explore the underlying mechanism, we found that metformin treatment could significantly damp the expression of 4EBP1 and S6K1 in KYSE 450 cells in vitro and in vivo, furthermore, the p-4EBP1 and p-S6K1 expression in KYSE 450 cells were also inhibited greatly in vitro and in vivo. During the therapy of cancer, in order to overcome side effects, combination therapy was often used. In this paper, we demonstrated that metformin potentiated the effects of cisplatin via inhibiting cell proliferation and promoting cell apoptosis. Taken together, metformin owned the potential anti-cancer effect on ESCC in monotherapy or was combined with cisplatin and these results laid solid basis for the use of metformin in ESCC.

miR-216b promotes cell growth and enhances chemosensitivity of colorectal cancer by suppressing PDZ-binding kinase

PDZ-binding kinase (PBK/TOPK) acts as oncogene in various cancers and correlates with drug response. However, few studies have examined the expression and roles of PBK in colonrectal cancer (CRC). In this study, we found a significant increase in the expression of PBK in CRC tissues and cell lines. While overexpression of PBK promoted cell growth and decreased the toxicity effect of oxaliplation (OXA), targeting PBK with short hairpin RNA (shRNA) or novel PBK inhibitor HI-TOPK-032 effectively suppressed tumor growth and potentiated chemosensitivity in vitro and in vivo. Furthermore, there was a significant inverse correlation between the expressions of miR-216b and PBK. Further found that miR-216b could down-regulate PBK levels by binding to the 3' untranslated region (3'UTR) of PBK. Notably, while miR-216b decreased cell proliferation and enhanced sensitivity of CRC cells to oxaliplation, re-expression of PBK dramatically reversed these events. Collectively, our data indicated that miR-216b may function as a tumor suppressor though regulating PBK expression, which provided promising targets and possible therapeutic strategies for CRC treatment.

Irinotecan Upregulates Fibroblast Growth Factor Receptor 3 Expression in Colorectal Cancer Cells, Which Mitigates Irinotecan-Induced Apoptosis

BACKGROUND: Irinotecan (IRI) is an integral part of colorectal cancer (CRC) therapy, but response rates are unsatisfactory and resistance mechanisms are still insufficiently understood. As fibroblast growth factor receptor 3 (FGFR3) mediates essential survival signals in CRC, it is a candidate gene for causing intrinsic resistance to IRI. METHODS: We have used cell line models overexpressing FGFR3 to study the receptor's impact on IRI response. For pathway blockade, a dominant-negative receptor mutant and a small molecule kinase inhibitor were employed. RESULTS: IRI exposure induced expression of FGFR3 as well as its ligands FGF8 and FGF18 both in cell cultures and in xenograft tumors. As overexpression of FGFR3 mitigated IRI-induced apoptosis in CRC cell models, this suggests that the drug itself activated a survival response. On the cellular level, the antiapoptotic protein bcl-xl was upregulated and caspase 3 activation was inhibited. Targeting FGFR3 signaling using a dominant-negative receptor mutant sensitized cells for IRI. In addition, the FGFR inhibitor PD173074 acted synergistically with the chemotherapeutic drug and significantly enhanced IRI-induced caspase 3 activity in vitro. In vivo, PD173074 strongly inhibited growth of IRI-treated tumors. CONCLUSION: Together, our results indicate that targeting FGFR3 can be a promising strategy to enhance IRI response in CRC patients.

The rs3957357C>T SNP in GSTA1 Is Associated with a Higher Risk of Occurrence of Hepatocellular Carcinoma in European Individuals

Glutathione S-transferases (GSTs) detoxify toxic molecules by conjugation with reduced glutathione and regulate cell signaling. Single nucleotide polymorphisms (SNPs) of GST genes have been suggested to affect GST functions and thus to increase the risk of human hepatocellular carcinoma (HCC). As GSTA1 is expressed in hepatocytes and the rs3957357C>T (TT) SNP is known to downregulate GSTA1 mRNA expression, the aims of this study were: (i) to explore the relationship between the TT SNP in GSTA1 and the occurrence of HCC; (ii) to measure GSTA1 mRNA expression in HCCs. For that purpose, we genotyped non-tumor-tissue-derived DNA from 48 HCC patients and white-blood-cell-derived DNA from 37 healthy individuals by restriction fragment length polymorphism (RFLP). In addition, expression of GSTA1 mRNA was assessed by real-time PCR in 18 matching pairs of HCCs and non-tumor livers. Survival analysis was performed on an annotated microarray dataset containing 247 HCC patients (GSE14520). The GSTA1 TT genotype was more frequent in HCC than in non-HCC patients (27% versus 5%, respectively), suggesting that individuals carrying this genotype could be associated with 2-fold higher risk of developing HCCs (odds ratio = 2.1; p = 0.02). Also, we found that GSTA1 mRNA expression was lower in HCCs than in non-tumor livers. HCCs expressing the highest GSTA1 mRNA levels were the smallest in size (R = -0.67; p = 0.007), expressed the highest levels of liver-enriched genes such as ALB (albumin, R = -0.67; p = 0.007) and COL18A1 (procollagen type XVIII, R = -0.50; p = 0.03) and showed the most favorable disease-free (OR = 0.54; p<0.001) and overall (OR = 0.56; p = 0.006) outcomes. Moreover, GSTA1 was found within a 263-gene network involved in well-differentiated hepatocyte functions. In conclusion, HCCs are characterized by two GSTA1 features: the TT SNP and reduced GSTA1 gene expression in a context of hepatocyte de-differentiation.

NOX2-ROS-HIF-1α signaling is critical for the inhibitory effect of oleanolic acid on rectal cancer cell proliferation

Rectal cancer is the second leading cause of cancer mortality in the western countries and accounts for 10% incidence and mortality of cancer in the whole world. Drug resistance and severe toxicity severely limited the efficiency of chemotherapy of rectal cancer. Oleanolic acid (OA) is a natural triterpenoid and an aglycone of many saponins. In the present study, we aimed to investigate the effect of OA on rectal cancer cell proliferation and its possible mechanism. We showed that OA concentration-dependently inhibited cell proliferation in HCT-15, HT-29, HCT-8 and Colo 205 human rectal cancer cell lines. OA significantly increased reactive oxygen species (ROS) generation and NADPH oxidase 2 (NOX2) expression in a concentration-dependent manner. In HCT-15 and HT-29 cells, siNOX2 notably suppressed OA-induced ROS generation, inhibition of cell proliferation, increase of S phase cell population and decrease of cyclin D1 and CDK2 expression. OA markedly decreased hypoxia-inducible factor 1α (HIF-1α) expression in HCT-15 and HT-29 cells in a concentration-dependent manner. Overexpression of HIF-1α significantly suppressed OA-induced inhibition of cell proliferation, increase of S phase cell population and decrease of cyclin D1 and CDK2 expression. Inhibition of NOX2 by siRNA notably blocked OA-induced suppression of HIF-1α expression. Our findings provide novel insights into OA-induced inhibition of rectal cancer cell proliferation and highlight NOX2/ROS/HIF-1α axis as a novel therapeutic target for the treatment of rectal cancer.

Impact of Systemic Therapy and Recurrence Pattern on Survival Outcome after Radiofrequency Ablation for Colorectal Liver Metastases

Background: Most patients undergoing radiofrequency ablation (RFA) of colorectal liver metastasases (CLM) develop disease recurrence, but little is known about the effect of recurrence patterns and/or systemic therapy on outcome. In this study, we examined the recurrence patterns and survival after systemic therapy plus RFA in patients with unresectable CLM without extrahepatic disease. The aims were to analyze the effect of recurrence patterns on survival and to assess the relative benefit contributed by systemic therapy and local ablation to disease control and patient outcome.

Methods: From January 2002 to December 2012, 113 patients underwent RFA of liver-limited CLM after systemic therapy. Univariate and multivariate analyses for associations between clinical and/or treatment-related variables, recurrence-free survival (RFS), recurrence patterns, and overall survival (OS) were carried out.

Results: Of 113 patients, 105 (92.8%) had disease recurrence (median RFS: 6.1 months). Lower post-recurrence OS was observed after early (≤6 months) than after late recurrence (8.5 versus 24.0 months, p < 0.001). Recurrence sites were RFA-sites only (4.8%), liver-only (57.1%), lung-only (10.5%), or multiple (27.6%); the corresponding post-recurrence OS was 21, 19, 39, and 7 months (p < 0.001), respectively. Response to pre-RFA systemic therapy was the strongest predictor for OS (hazard ratio [HR] 5.28), RFS (HR 3.30), early (odds ratio [OR] 6.34) and multiple-site recurrence (OR 3.83) (p < 0.01), respectively; only responders achieved 5-year OS and RFS (29% and 12% versus 0% and 0% for non-responders, p < 0.001, respectively).

Conclusions: Survival after RFA for liver-limited CLM is strongly linked to the timing and pattern of non-local disease recurrence. Local ablation efficacy is necessary but not sufficient to obtain long-term disease control. Effective pre-RFA systemic therapy does favourably affect the incidence, timing and patterns of recurrence and long-term survival and appears essential for the tailoring of RFA application to maximize patient benefit.

Spindle Assembly Checkpoint as a Potential Target in Colorectal Cancer: Current Status and Future Perspectives

Colorectal cancer (CRC), one of the most common malignancies worldwide, is often diagnosed at an advanced stage, and resistance to chemotherapeutic and existing targeted therapy is a major obstacle to its successful treatment. New targets that offer alternative clinical options are therefore urgently needed. Recently, perturbation of the spindle assembly checkpoint (SAC), the surveillance mechanism that maintains anaphase inhibition until all chromosomes reach the metaphase plate, has been regarded as a promising target to fight cancer cells, either alone or in combination regimens. Consistent with this strategy, many cancers, including CRC, exhibit altered expression of SAC genes. In this article, we review our current knowledge on SAC activity status in CRC, and on current anti-CRC strategies and future therapeutic perspectives on the basis of SAC targeting experiments in vitro and in animal models.

Pharmacologic resistance in colorectal cancer: a review

Colorectal cancer (CRC) persists as one of the most prevalent and deadly tumor types in both men and women worldwide. This is in spite of widespread, effective measures of preventive screening, and also major advances in treatment options. Despite advances in cytotoxic and targeted therapy, resistance to chemotherapy remains one of the greatest challenges in long-term management of incurable metastatic disease and eventually contributes to death as tumors accumulate means of evading treatment. We performed a comprehensive literature search on the data available through PubMed, Medline, Scopus, and the ASCO Annual Symposium abstracts through June 2015 for the purpose of this review. We discuss the current state of knowledge of clinically relevant mechanisms of resistance to cytotoxic and targeted therapies now in use for the treatment of CRC.

Dimethyl fumarate induces necroptosis in colon cancer cells through GSH depletion/ROS increase/MAPKs activation pathway

BACKGROUND AND PURPOSE

Dimethyl fumarate (DMF) is a newly approved drug for the treatment of relapsing forms of multiple sclerosis and relapsing-remitting multiple sclerosis. Here, we investigated the effects of DMF and its metabolites mono-methylfumarate (MMF and methanol) on different gastrointestinal cancer cell lines and the underlying molecular mechanisms involved.

EXPERIMENTAL APPROACH

Cell viability was measured by the MTT or CCK8 assay. Protein expressions were measured by Western blot analysis. LDH release, live- and dead-cell staining, intracellular GSH levels, and mitochondrial membrane potential were examined by using commercial kits.

KEY RESULTS

DMF but not MMF induced cell necroptosis, as demonstrated by the pharmacological tool necrostatin-1, transmission electron microscopy, LDH and HMGB1 release in CT26 cells. The DMF-induced decrease in cellular GSH levels as well as cell viability and increase in reactive oxygen species (ROS) were inhibited by co-treatment with GSH and N-acetylcysteine (NAC) in CT26 cells. DMF activated JNK, p38 and ERK MAPKs in CT26 cells and JNK, p38 and ERK inhibitors partially reversed the DMF-induced decrease in cell viability. GSH or NAC treatment inhibited DMF-induced JNK, p38, and ERK activation in CT26 cells. DMF but not MMF increased autophagy responses in SGC-7901, HCT116, HT29 and CT26 cancer cells, but autophagy inhibition did not prevent the DMF-induced decrease in cell viability.

CONCLUSION AND IMPLICATIONS

DMF but not its metabolite MMF induced necroptosis in colon cancer cells through a mechanism involving the depletion of GSH, an increase in ROS and activation of MAPKs.