TCF4 silencing sensitizes the colon cancer cell line to oxaliplatin as a common chemotherapeutic drug

Kallistatin as an inhibitory protein against colorectal cancer cells through binding to LRP6

Kallistatin (KL) is a member of the serine proteinase inhibitor (serpin) family regulating oxidative stress, vascular relaxation, inflammation, angiogenesis, cell proliferation, and invasion. The heparin-binding site of Kallistatin has an important role in the interaction with LRP6 leading to the blockade of the Wnt signaling pathway. In this study, we aimed to explore the structural basis of the Kallistatin-LRP6E1E4 complex using in silico approaches and evaluating the anti-proliferative, apoptotic, and cell cycle arrest activities of Kallistatin in colon cancer lines. The molecular docking showed Kallistatin could bind to the LRP6E3E4 much stronger than LRP6E1E2. The Kallistatin-LRP6E1E2 and Kallistatin-LRP6E3E4 complexes were stable during Molecular Dynamics (MD) simulation. The Molecular Mechanics/Poisson-Boltzmann Surface Area (MM/PBSA) showed that the Kallistatin-LRP6E3E4 has a higher binding affinity compared to Kallistatin-LRP6E1E2. Kallistatin induced higher cytotoxicity and apoptosis in HCT116 compared to the SW480 cell line. This protein-induced cell-cycle arrest in both cell lines at the G1 phase. The B-catenin, cyclin D1, and c-Myc expression levels were decreased in response to treatment with Kallistatin in both cell lines while the LRP6 expression level was decreased in the HCT116 cell line. Kallistatin has a greater effect on the HCT116 cell line compared to the SW480 cell line. Kallistatin can be used as a cytotoxic and apoptotic-inducing agent in colorectal cancer cell lines.

Cancer stem cells in colorectal cancer: Signaling pathways involved in stemness and therapy resistance

Colorectal cancer (CRC) is the third cause of cancer death worldwide. Although, in some cases, treatment can increase patient survival and reduce cancer recurrence, in many cases, tumors can develop resistance to therapy leading to recurrence. One of the main reasons for recurrence and therapy resistance is the presence of cancer stem cells (CSCs). CSCs possess a self-renewal ability, and their stemness properties lead to the avoidance of apoptosis, and allow a new clone of cancer cells to emerge. Numerous investigations inidicated the involvment of cellular signaling pathways in embryonic development, and growth, repair, and maintenance of tissue homeostasis, also participate in the generation and maintenance of stemness in colorectal CSCs. This review discusses the role of Wnt, NF-κB, PI3K/AKT/mTOR, Sonic hedgehog, and Notch signaling pathways in colorectal CSCs, and the possible modulating drugs that could be used in treatment for resistant CRC.

LEF1 silencing sensitizes colorectal cancer cells to oxaliplatin, 5-FU, and irinotecan

Colorectal cancer (CRC) is the third most prevalent cancer all around the world. Chemotherapy plays an essential role in the treatment of CRC while Oxaliplatin, Irinotecan, and 5 - fluorouracil (5-FU) are the most commonly used chemotherapeutic drugs. However, chemo-resistance is a major obstacle to successful therapy. It has been shown that inhibition of Wnt signaling pathway can sensitize the cells to chemotherapy. Lymphoid enhancer factor (LEF1) is a member of TCF/LEF transcription family mediating Wnt nuclear responses. The long isoform of LEF1 is highly expressed in colorectal cancer cells compared to the normal intestinal cells, in which expression of the short isoform is dominant. We found that the downregulation of long isoforms of LEF1 makes CRC cell lines more sensitive to the effect of chemotherapeutic drugs. This sensitivity is imposed by reduced proliferation, increased apoptosis, or cell cycle arrest. Our results also demonstrated that there is a balance in the expression of long, and short isoforms of LEF1. In summary, we showed the role of LEF1 in chemo-resistance of colorectal cancer cells to Oxaliplatin, Irinotecan and 5-FU.

Mechanisms of Immune Escape and Resistance to Checkpoint Inhibitor Therapies in Mismatch Repair Deficient Metastatic Colorectal Cancers

Simple Summary

A subset of colorectal cancers (CRCs) is characterized by a mismatch repair deficiency that is frequently associated with microsatellite instability (MSI). The compromised DNA repair machinery leads to the accumulation of tumor neoantigens affecting the sensitivity of MSI metastatic CRC to immune checkpoint inhibitors (CPIs), both upfront and in later lines of treatment. However, up to 30% of MSI CRCs exhibit primary resistance to frontline immune based therapy, and an additional subset develops acquired resistance. Here, we first discuss the clinical and molecular features of MSI CRCs and then we review how the loss of antigenicity, immunogenicity, and a hostile tumor microenvironment could influence primary and acquired resistance to CPIs. Finally, we describe strategies to improve the outcome of MSI CRC patients upon CPI treatment.

Abstract

Immune checkpoint inhibitors (CPIs) represent an effective therapeutic strategy for several different types of solid tumors and are remarkably effective in mismatch repair deficient (MMRd) tumors, including colorectal cancer (CRC). The prevalent view is that the elevated and dynamic neoantigen burden associated with the mutator phenotype of MMRd fosters enhanced immune surveillance of these cancers. In addition, recent findings suggest that MMRd tumors have increased cytosolic DNA, which triggers the cGAS STING pathway, leading to interferon-mediated immune response. Unfortunately, approximately 30% of MMRd CRC exhibit primary resistance to CPIs, while a substantial fraction of tumors acquires resistance after an initial benefit. Profiling of clinical samples and preclinical studies suggests that alterations in the Wnt and the JAK-STAT signaling pathways are associated with refractoriness to CPIs. Intriguingly, mutations in the antigen presentation machinery, such as loss of MHC or Beta-2 microglobulin (B2M), are implicated in initial immune evasion but do not impair response to CPIs. In this review, we outline how understanding the mechanistic basis of immune evasion and CPI resistance in MMRd CRC provides the rationale for innovative strategies to increase the subset of patients benefiting from CPIs.

Wnt/β‑catenin signaling: Causes and treatment targets of drug resistance in colorectal cancer (Review)

Colorectal cancer (CRC) is the third most common malignant tumor in humans. Chemotherapy is used for the treatment of CRC. However, the effect of chemotherapy remains unsatisfactory due to drug resistance. Growing evidence has shown that the presence of highly metastatic tumor stem cells, regulation of non-coding RNAs and the tumor microenvironment contributes to drug resistance mechanisms in CRC. Wnt/β-catenin signaling mediates the chemoresistance of CRC in these three aspects. Therefore, the present study analyzed the abundant evidence of the contribution of Wnt/β-catenin signaling to the development of drug resistance in CRC and discussed its possible role in improving the chemosensitivity of CRC, which may provide guidelines for its clinical treatment.

Identification of candidate genes and miRNAs for sensitizing resistant colorectal cancer cells to oxaliplatin and irinotecan

Drug resistance to irinotecan and oxaliplatin, two widely used chemotherapeutic, has become a common problem in cancerous patients. Despite numerous valuable studies, distinct molecular mechanisms involved in the acquisition of resistance to these anti-cancer drugs have remained a challenge. In this study, we studied the possible resistance mechanisms to irinotecan and oxaliplatin in three CRC cell lines (HCT116, HT29, and LoVo) via integration of microarray data with gene regulatory networks. After determination of hub genes, corresponding miRNAs were predicted using several databases and used in construction and subsequent analysis of miRNA-gene networks. Following to preparation of chemo-resistance CRC cells, a standard real-time PCR was conducted for validation of in silico findings. Topological and functional enrichment analyses of the resulted networks introduced several previously reported drug-resistance genes as well as novel biomarkers as hub genes which seem to be crucial in resistance of colon cancer cells to irinotecan and oxaliplatin. Furthermore, results of the functional annotation revealed the essential role of different signaling pathways like metabolic pathways in drug resistance of CRC cell lines to these drugs. A part of in silico findings was also validated in vitro using oxaliplatin-resistant cell lines. While FOXC1 and NFIC were upregulated in cell lines which were resistant to oxaliplatin, silencing FOXC1 decreased the resistance of SW480 cell line to oxaliplatin. In conclusion, our comparative in silico and in vitro study introduces several novel genes and miRNAs as the resistance-mediators which can be used for sensitizing resistant CRC cells to oxaliplatin and irinotecan.

Effect of oxaliplatin combined with 5-fluorouracil on treatment efficacy of radiotherapy in the treatment of elderly patients with rectal cancer

Efficacy of the combination of oxaliplatin, 5-fluorouracil and radiotherapy on rectal cancer in elderly patients was investigated. Seventy-three elderly patients with rectal cancer confirmed by histopathological examination were randomly divided into 3 groups: oxaliplatin group (25 cases): intravenous infusion of oxaliplatin; fluorouracil group (24 cases): intravenous infusion of fluorouracil; combination group (24 cases), intravenous infusion of oxaliplatin and fluorouracil. All patients were treated with radiotherapy, and efficacy and safety were evaluated after 2 courses of treatment. MTT assay was used to observe the inhibitory effects of the proliferation of human rectal cancer cells. Cell proliferation and sensitization ratios were compared. After 2 courses of treatment, there was no difference in complete remission (CR), partial remission (PR), stable disease (SD), progression disease (PD) and disease control rate (DCR). Remission rate (RR) was higher in the combination group than that in the oxaliplatin and the fluorouracil groups (P<0.05), and there was no difference between the oxaliplatin and the fuorouracil group (P>0.05). Incidence of neutropenia in the combination group was higher than that in the fluorouracil group (P<0.05). OD values of the combination group were lower than those of the oxaliplatin and the fluorouracil groups (P<0.05). Proliferation ability of SW837 cells of the combination group was significantly lower than that of the oxaliplatin and the fluorouracil groups (P<0.05). Intragroup comparison of sensitization ratio showed that sensitization ratios of three groups of cells at 24, 48 and 72 h were all higher than those at 12 h (P<0.05). The combination of oxaliplatin and 5-fluorouracil is safe and effective in the treatment of rectal cancer in elderly patients, and it can be used for sensitization of radiotherapy. So it should be popularized in clinical practices.

Through oxaliplatin resistance induction in colorectal cancer cells, increasing ABCB1 level accompanies decreasing level of miR-302c-5p, miR-3664-5p and miR-129-5p

Oxaliplatin as a component of (Neo-) adjuvant chemotherapeutic regimens is administered to colorectal cancer patients. Unfortunately, the acquisition of resistance to this drug in nearly 90% of metastatic patients rendered it as an ineffective drug. Therefore, resistance mechanisms to this drug should be elucidated. There are different genes like GSTP1 and ABCB1 which are responsible for oxaliplatin resistance. We hypothesized that miR-129-5p, miR-302c-5p, miR-3664-5p, mir-3714 and miR-513a-3p are targeting ABCB1 gene, while GSTP1 was predicted to be the potential target of miR-3664-5p, mir-3714 and miR-513a-3p. In order to study this hypothesis, resistant colorectal cell lines were generated through intermittent exposure of HCT116, SW480 and HT29 to the increasing doses of oxaliplatin. MTT assays validated this resistance induction. Expression of ABCB1 and GSTP1 in addition to their targeting miRNAs in different cell lines were studied by quantitative real time PCR in the cell lines. Even though in comparison with HCT116 and SW480 cell lines, GSTP1 expression was reduced in resistant cells, ABCB1 expression was upregulated in these cell lines. On the other hand, HT-29 resistant cells showed elevated GSTP1 and unchanged ABCB1 levels. While miR-302c-5p level was downregulated in resistant cell lines, miR-129-5p and miR-3664-5p level showed different pattern of reduction in the resistant SW480 and HCT116 cell lines. GSTP1 level was correlated directly with miR-513a-3p and miR-3664-5p in all SW480 and HCT116 derived cell lines, however in HT-29-OXR1, GSTP1 level was correlated inversely with miR-3664-5p. In conclusion, upregulation of ABCB1 can be considered as the crucial component of poor response to oxaliplatin which is likely controlled by miR-302c-5p.

NFYB-induced high expression of E2F1 contributes to oxaliplatin resistance in colorectal cancer via the enhancement of CHK1 signaling

As a third-generation platinum drug, oxaliplatin has been widely applied in colorectal cancer (CRC); however, acquired resistance to oxaliplatin has become a major obstacle. In the present study, we found that the nuclear transcription factor Y subunit beta (NFYB) and E2F transcription factor 1 (E2F1) expression levels were significantly higher in oxaliplatin-resistant DLD1 and RKO CRC (OR-CRC) cells than in non-resistant cells. Additionally, highly expressed NFYB transactivated the E2F1 gene, which is important to maintain oxaliplatin resistance in OR-CRC cells. And Sirt1-dependent deacetylation suppresses the proapoptotic activity of E2F1 in OR-CRC cells. Through profiling the transcriptome of OR-CRC cells following E2F1 knockdown, CHK1 was identified as a target of E2F1. Deprivation of CHK1 sensitized OR-CRC cells to oxaliplatin. In vitro and in vivo phenotype experiments confirmed that an intact NFYB-E2F1-CHK1 axis was required to suppress oxaliplatin-induced apoptosis and maintain the tumorigenicity in OR-CRC cells. Knockdown of E2F1 in OR-CRC cells also decreased the expression of Pol κ, which was essential for CHK1 activation. Consistently, a high level of NFYB, E2F1, or CHK1 predicted poor survival in CRC patients, especially with oxaliplatin treatment. Collectively, the NFYB-E2F1 pathway displays a crucial role in the chemoresistance of OR-CRC by inducing the expression and activation of CHK1, providing a possible therapeutic target for oxaliplatin resistance in CRC.

MiR-608 regulating the expression of ribonucleotide reductase M1 and cytidine deaminase is repressed through induced gemcitabine chemoresistance in pancreatic cancer cells

PURPOSE

Gemcitabine resistance is the main problem in pancreatic adenocarcinoma patients. Hence, we aimed to identify the correlation between expression of RRM1 and CDA as the resistance genes and their predicted targeting miR-608 in the resistant pancreatic cancer cell lines to gemcitabine.

METHODS

Dual luciferase assay was performed to determine whether both RRM1 and CDA are targeted by miR-608 in 293T and pancreatic cancer cell lines. AsPC-1 and MIA PaCa-2 cell lines became gradually resistant to gemcitabine by exposing to the increasing doses of gemcitabine. After RNA and miRNAs extraction and cDNA conversion, the expressions of RRM1, CDA and miR-608 in all cell lines were studied by quantitative PCR. Pre-miR-608 transfection to the cell lines was done by calcium phosphate method. MTT assay was performed for analyzing the chemo sensitivity of different cell lines to gemcitabine.

RESULTS

Luciferase assays showed that miR-608 targeted RRM1 and CDA genes in 293T, AsPC-1 and MIA PaCa-2 cell lines. Compared to parental cell line, resistant MIA PaCa-2 and AsPC-1 cells demonstrated increased expression of RRM1 and CDA. On the other hand the expression of miR-608 in resistant MIA PaCa-2 and AsPC-1 cells was lower than parental cells. Furthermore, transfection of MIA PaCa-2 and AsPC-1 cells by miR-608 lead to decreased expression of RRM1 and CDA and lowered viability of the cells in comparison with scrambled microRNA transfected cells.

CONCLUSION

During resistance induction in pancreatic cancer cells, miR-608 which is targeting RRM1 and CDA is downregulated which leads to upregulation of these genes.

A83-01 inhibits TGF-β-induced upregulation of Wnt3 and epithelial to mesenchymal transition in HER2-overexpressing breast cancer cells

PURPOSE

The aim of this study is to investigate the mechanisms of interactions between TGF-β and Wnt/β-catenin pathways that induce and regulate EMT and promote breast cancer cells to become resistant to treatment.

METHODS

The effect of TGF-β on Wnt/β-catenin signaling pathway was examined by using a human Wnt/β-catenin-regulated cDNA plate array and western blot analysis. The interaction of Twist at promoter of Wnt3 was examined by chromatin immunoprecipitation (ChIP) assay. Secreted Wnt3 level was determined by ELISA assay.

RESULTS

HER2-overexpressing breast cancer cells treated with TGF-β have a reduced response to trastuzumab and exhibited EMT-like phenotype. The TGF-β-induced EMT in HER2-cells was concordant with upregulation of Wnt3 and β-catenin pathways. The TGF-β-induced induction of Wnt3 during EMT was found to be Smad3-dependent. ChIP analysis identified occupancy of Twist at promoter region of Wnt3. Knock-down of Twist by shRNA confirmed the significance of Twist in response to TGF-β regulating Wnt3 during EMT. Subsequently, TGF-β-induced matrix metalloproteinases, MMP1, MMP7, MMP9, MMP26, Vascular endothelial growth factors (VEGF), and activation of Wnt/β-catenin signaling were repressed by the shRNA treatment. TGF-βR1 ALK5 kinase inhibitor, A83-01 can effectively prevent the TGF-β-induced Twist and Wnt3. Co-treating A83-01 and trastuzumab inhibited TGF-β-induced cell invasion significantly in both trastuzumab responsive and resistant cells.

CONCLUSIONS

Our data demonstrated an important interdependence between TGF-β and Wnt/β-catenin pathways inducing EMT in HER2-overexpressing breast cancer cells. Twist served as a linkage between the two pathways during TGF-β-induced EMT. A83-01 could inhibit the TGF-β-initiated pathway interactions and enhance HER2-cells response to trastuzumab treatment.

Molecular alterations contributing to pancreatic cancer chemoresistance

Pancreatic ductal adenocarcinoma (PDAC) is one of the most common causes of cancer-related death all over the world. This disease is difficult to treat and patients have an overall 5-year survival rate of less than 5%. Although two drugs, gemcitabine (GEM) and 5-fluorouracil (5-FU) have been shown to improve the survival rate of patients systematically, they do not increase general survival to a clinically acceptable degree. Lack of ideal clinical response of pancreatic cancer patients to chemotherapy is likely to be due to intrinsic and acquired chemoresistance of tumor cells. Various mechanisms of drug resistance have been investigated in pancreatic cancer, including genetic and epigenetic changes in particular genes or signaling pathways. In addition, evidence suggests that microRNAs (miRNAs) play significant roles as key regulators of gene expression in many cellular processes, including drug resistance. Understanding underlying genes and mechanisms of drug resistance in pancreatic cancer is critical to develop new effective treatments for this deadly disease. This review illustrates the genes and miRNAs involved in resistance to gemcitabine in pancreatic cancer.

Exosome-derived microRNAs contribute to prostate cancer chemoresistance

Certain microRNAs (miRNAs) play a key role in cancer cell chemoresistance. However, the pleiotropic functions of exosome-derived miRNAs on developing chemoresistance remain unknown. In the present study, we aimed to construct potential networks of miRNAs, which derived from the exosome of chemoresistant prostate cancer (PCa) cells, with their known target genes using miRNA expression profiling and bioinformatic tools. Global miRNA expression profiles were measured by microarray. Twelve miRNAs were initially selected and validated by qRT-PCR. Known targets of deregulated miRNAs were utilized using DIANA-TarBase database v6.0. The incorporation of deregulated miRNAs and target genes into KEGG pathways were utilized using DIANA-mirPath software. To construct potential miRNA regulatory networks, the overlapping parts of miRNAs and their targer genes from the selected KEGG pathway 'PCa progression (hsa05215)' were visualized by Cytoscape software. We identified 29 deregulated miRNAs, including 19 upregulated and 10 downregulated, in exosome samples derived from two kinds of paclitaxel resistance PCa cells (PC3-TXR and DU145-TXR) compared with their parental cells (PC3 and DU145). The enrichment results of deregulated miRNAs and known target genes showed that a few pathways were correlated with several critical cell signaling pathways. We found that hub hsa-miR3176, -141-3p, -5004-5p, -16-5p, -3915, -488‑3p, -23c, -3673 and -3654 were potential targets to hub gene androgen receptor (AR) and phosphatase and tensin homolog (PTEN). Hub gene T-cell factors/lymphoid enhancer-binding factors 4 (TCF4) target genes were mainly regulated by hub hsa-miR-32-5, -141-3p, -606, -381 and -429. These results may provide a linkage between PCa chemoresistance and exosome regulatory networks and thus lead us to propose that AR, PTEN and TCF4 genes may be the important genes which are regulated by exosome miRNAs in chemoresistance cancer cells.

Epithelial-Mesenchymal Transition and Breast Cancer

Breast cancer is the most common cancer in women and distant site metastasis is the main cause of death in breast cancer patients. There is increasing evidence supporting the role of epithelial-mesenchymal transition (EMT) in tumor cell progression, invasion, and metastasis. During the process of EMT, epithelial cancer cells acquire molecular alternations that facilitate the loss of epithelial features and gain of mesenchymal phenotype. Such transformation promotes cancer cell migration and invasion. Moreover, emerging evidence suggests that EMT is associated with the increased enrichment of cancer stem-like cells (CSCs) and these CSCs display mesenchymal characteristics that are resistant to chemotherapy and target therapy. However, the clinical relevance of EMT in human cancer is still under debate. This review will provide an overview of current evidence of EMT from studies using clinical human breast cancer tissues and its associated challenges.

SW480 colorectal cancer cells that naturally express Lgr5 are more sensitive to the most common chemotherapeutic agents than Lgr5-negative SW480 cells

Leucine-rich repeat containing G protein-coupled receptor 5 (Lgr5) is a colorectal cancer (CRC) stem cell marker. The role of Lgr5-expressing stem cells in resistance to chemotherapy is controversial. The notion that Lgr5-expressing cells are more chemotherapy resistant is supported by some data; other data do not support this notion. We hypothesized that Lgr5-expressing cells would be more chemotherapy sensitive, as Lgr5 is usually a marker of dividing cells. We tested this hypothesis by exploiting two natural variants of SW480 CRC cells: the less-differentiated Lgr5-expressing floating fraction and the more-differentiated Lgr5-depleted attached fraction. We estimated chemotherapy sensitivity using an XTT Cell Proliferation Assay Kit. We confirmed that the detected chemotherapy sensitivity differences were Lgr5-driven by overexpressing Lgr5. SW480 CRC cells that naturally express Lgr5 are those that are floating, and they are more sensitive to the chemotherapeutic compounds irinotecan (maximum difference approximately two times, 0.0001<P<0.0052) and oxaliplatin (maximum difference ∼1.5 times, 0.0001<P<0.0024) than Lgr5-negative (attached) SW480 cells. At IC50, the difference in sensitivity between these two fractions of SW480 cells to the drugs was twice as prominent with irinotecan as with oxaliplatin (P<0.0001). SW480 cells that naturally express Lgr5 were slightly more sensitive to 5-fluorouracil than non-Lgr5-expressing cells (0.0002<P<0.0344). Transfected Lgr5-overexpressing attached cells showed similar results with irinotecan and oxaliplatin, confirming that the detected differences in sensitivity to these drugs were Lgr5 driven. Most likely, Lgr5 makes cells vulnerable to chemotherapy, increasing their propensity to divide through activation of the Wnt/β-catenin pathway. There is one exception, Lgr5-overexpressing cells did not show this increase in sensitivity to 5-fluorouracil. Remarkably, Lgr5 reduced the number of floating cells two-fold (instead of increasing it, as one would expect from a stemness-determining factor) and slightly increased the number of attached differentiated cells at a significantly high transfection efficiency for these SW480 cells (∼30%). These results suggest that Lgr5, although purported to be a cancer stem cell marker, is not sufficient to promote floating in these colon cancer cells. In conclusion, CRC cells that naturally express Lgr5 are more sensitive to the most commonly used CRC chemotherapeutic compounds than those that are naturally Lgr5 negative.

miR-203 downregulates Yes-1 and suppresses oncogenic activity in human oral cancer cells

The purpose of this study was to elucidate the molecular mechanisms of microRNA-203 (miR-203) as a tumor suppressor in KB human oral cancer cells. MicroRNA microarray results showed that the expression of miR-203 was significantly down-regulated in KB cells compared with normal human oral keratinocytes. The viability of KB cells was decreased by miR-203 in the time- and dose-dependent manners. In addition, over-expressed miR-203 not only increased the nuclear condensation but also significantly increased the apoptotic population of KB cells. These results indicated that the over-expression of miR-203 induced apoptosis of KB cells. Furthermore, the target gene array analyses revealed that the expression of Yes-1, a member of the Src family kinases (SFKs), was significantly down-regulated by miR-203 in KB cells. Moreover, both the mRNA and protein levels of Yes-1 were strongly reduced in KB cells transfected with miR-203. Therefore, these results indicated that Yes-1 is predicted to be a potential target gene of miR-203. Through a luciferase activity assay, miR-203 was confirmed to directly targets the Yes-1 3' untranslated region (UTR) to suppress gene expression. Therefore, our findings indicate that miR-203 induces the apoptosis of KB cells by directly targeting Yes-1, suggesting its application in anti-cancer therapeutics.