Prediction of efficacy and side effects of chemotherapy in colorectal cancer

Metformin and ICG-001 Act Synergistically to Abrogate Cancer Stem Cells-Mediated Chemoresistance in Colorectal Cancer by Promoting Apoptosis and Autophagy

Simple Summary

Colorectal cancer (CRC) is one of the most frequently diagnosed and lethal malignancies. The majority of CRC patients experience disease relapse after the primary curative treatment strategy of surgery followed by 5FU-based chemotherapy. The presence of cancer stem-like cells (CSCs) is considered to be one of the contributing factors to therapy resistance and disease relapse in CRC. Previous studies implicated the role of the Wnt signaling pathway in the maintenance of the CSC phenotype. Therefore, in this study we explored a novel therapeutic strategy using metformin along with ICG-001, a Wnt signaling inhibitor, to abrogate CSC-mediated chemoresistance in CRC. We observed that metformin and ICG-001 abrogate stemness in a synergistic manner by promoting autophagy and apoptosis in 5FU-resistant CRC cells as well as in CRC patient-derived tumor organoids. Hence, metformin and ICG-001 can be used as part of a therapeutic strategy to overcome 5FU-mediated therapeutic resistance in CRC.

Abstract

Colorectal cancer (CRC) remains the third most frequently diagnosed cancer in the United States. The current treatment regimens for CRC include surgery followed by 5FU-based chemotherapy. Cancer stem-like cells (CSCs) have been implicated in 5FU-mediated chemoresistance, which leads to poor prognosis. In this study, we used metformin along with ICG-001, a Wnt signaling inhibitor, to abrogate CSC-mediated chemoresistance in CRC. We observed that 5FU-resistant (5FUR) CRC cells exhibited increased expression of CSC markers and enhanced spheroid formation. Genome-wide transcriptomic profiling analysis revealed that Wnt signaling, colorectal cancer metastasis signaling, etc., were enriched in 5FUR CRC cells. Accordingly, selective targeting of Wnt signaling using ICG-001 along with metformin abrogated CSC-mediated chemoresistance by decreasing the expression of CSC markers and promoting autophagy and apoptosis in a synergistic manner. We also observed that metformin and ICG-001 exhibited anti-tumor activity in CRC patient-derived tumor organoids. In conclusion, our study highlights that metformin and ICG-001 act synergistically and can be used as part of a therapeutic strategy to overcome 5FU-mediated therapeutic resistance in CRC.

A novel coordination complex of platinum (PT) induces cell death in colorectal cancer by altering redox balance and modulating MAPK pathway

Background

Colorectal cancer (CRC) is a heterogeneous tumor having various genetic alterations. The current treatment options had limited impact on disease free survival due to therapeutic resistance. Novel anticancer agents are needed to treat CRC specifically metastatic colorectal cancer. A novel coordination complex of platinum, (salicylaldiminato)Pt(II) complex with dimethylpropylene linkage (PT) exhibited potential anti-cancer activity. In this study, we explored the molecular mechanism of PT-induced cell death in colorectal cancer.

Methods

Colony formation was evaluated using the clonogenic assay. Apoptosis, cell cycle analysis, reactive oxygen species, mitochondrial membrane potential and caspase-3/− 7 were assessed by flow cytometry. Glutathione level was detected by colorimetric assay. PT-induced alteration in pro-apoptotic/ anti-apoptotic proteins and other signaling pathways were investigated using western blotting. P38 downregulation was performed using siRNA.

Results

In the present study, we explored the molecular mechanism of PT-mediated inhibition of cell proliferation in colorectal cancer cells. PT significantly inhibited the colony formation in human colorectal cancer cell lines (HT-29, SW480 and SW620) by inducing apoptosis and necrosis. This platinum complex was shown to significantly increase the reactive oxygen species (ROS) generation, depletion of glutathione and reduced mitochondrial membrane potential in colorectal cancer cells. Exposure to PT resulted in the downregulation of anti-apoptotic proteins (Bcl2, BclxL, XIAP) and alteration in Cyclins expression. Furthermore, PT increased cytochrome c release into cytosol and enhanced PARP cleavage leading to activation of intrinsic apoptotic pathway. Moreover, pre-treatment with ROS scavenger N-acetylcysteine (NAC) attenuated apoptosis suggesting that PT-induced apoptosis was driven by oxidative stress. Additionally, we show that PT-induced apoptosis was mediated by activating p38 MAPK and inhibiting AKT pathways. This was demonstrated by using chemical inhibitor and siRNA against p38 kinase which blocked the cytochrome c release and apoptosis in colorectal cancer cells.

Conclusion

Collectively, our data demonstrates that the platinum complex (PT) exerts its anti-proliferative effect on CRC by ROS-mediated apoptosis and activating p38 MAPK pathway. Thus, our findings reveal a novel mechanism of action for PT on colorectal cancer cells and may have therapeutic implication.

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.

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.

The EGF 61A/G polymorphism - a predictive marker for recurrence of liver metastases from colorectal cancer

BACKGROUND

Epidermal growth factor (EGF) plays an important role in tumorigenesis. Variations in the DNA sequence of the gene EGF can lead to alterations in EGF activity, which is suspected to influence tumor progression. This retrospective study aimed to investigate the influence of EGF 61A/G polymorphism on the recurrence of liver metastases after hepatic surgery in patients with colorectal cancer.

METHODS

EGF 61A/G polymorphism was determined in 268 consecutive patients (175 [65%] men and 93 [35%] women, mean age 62 +/- 10.3 years) who had liver metastases at primary diagnosis and were treated by surgery with curative intent (R0) for liver metastases from colorectal cancer.

RESULTS

Overall, 81 of 268 (30%) patients exhibited wild-type EGF 61 A/A, 137 (51%) were heterozygous EGF 61 A/G and 50 (19%) were homozygous EGF 61 G/G. After adjusting for age, sex, UICC stage and tumor location, we observed a trend-wise 1.6-fold increased risk for hepatic recurrence (HR 1.6; 95% CI 1.0-2.5, P = 0.06) in individuals with the G/G genotype compared with carriers of the A-allele. The effect was much more pronounced in younger patients (<or= 65 years), who showed a 2.0-fold increased risk of hepatic recurrence (HR 2.0; 95% CI 1.1-3.5, P = 0.021). No effect was observed in older patients (>or= 65 years). Interestingly, male patients with EGF G/G had a 1.6-fold higher risk of recurrence (HR 1.6; 95% CI 1.0-2.5, P = 0.07). A significant correlation (P = 0.033) was detected between Dukes classification and the homozygous 61 G/G genotype.

CONCLUSION

Despite the limitations of our study, the retrospective results indicate that carriers of the EGF polymorphism might be at higher risk of developing liver recurrences. If confirmed in subsequent studies, genotyping for the EGF A/G variant might help in identification of patients at high risk of recurrence of liver metastases.

Targeted treatment using monoclonal antibodies and tyrosine-kinase inhibitors in pregnancy

An expanding knowledge of the signalling pathways involved in the cell cycle has led to great improvements in the understanding of the molecular events involved in carcinogenesis. The past decade has seen substantial advances with the introduction of several classes of targeted therapeutics for the treatment of various cancers and autoimmune disorders. However, the question arises as to whether pregnant women can take advantage of these new treatments in view of the potential risks to the fetus. Published work suggests that biological agents, like traditional treatments, have the potential to affect the fetus, and should, therefore, be used with caution during pregnancy. However, when targeted treatment is clearly indicated the magnitude of the risk to the fetus might not reach that of standard chemotherapy. In circumstances where better alternative treatments do not exist, or where failure to use targeted treatments would result in suboptimum patient care or survival, the risk-benefit analysis might favour the use of potentially effective molecular treatment during pregnancy.