Chemoresistance Of Colorectal Cancer Cells Research Articles

HTRA1 interacts with SLC7A11 to modulate colorectal cancer chemosensitivity by inhibiting ferroptosis

Chemotherapy is an important therapuetic strategy for colorectal cancer (CRC), but chemoresistance severely affects its efficacy, and the underlying mechanism has not been fully elucidated. Increasing evidence suggests that lipid peroxidation imbalance-mediated ferroptosis is closely associated with chemoresistance. Hence, targeting ferroptosis pathways or modulating the tolerance to oxidative stress might be an effective strategy to reverse tumor chemoresistance. HtrA serine protease 1 (HTRA1) was screened out as a CRC progression- and chemoresistance-related gene. It is highly expressed in CRC cells and negatively correlated with the prognosis of CRC patients. Gain- and loss-of-function analyses demonstrated a stimulatory role of HTRA1 on the proliferation of CRC cells. The enrichment analysis of HTRA1-interacting proteins indicated the involvement of ferroptosis in the HTRA1-mediated chemoresistance. Moreover, electron microscope analysis, as well as the ROS and MDA levels in CRC cells also confirmed the effect of HTRA1 on ferroptosis. We also verified that HTRA1 could interact with SLC7A11 through its Kazal structural domain and up-regulate the expression of SLC7A11, which in turn inhibited the ferroptosis and leaded to the chemoresistance of CRC cells to 5-FU/L-OHP. Hence, we propose that HTRA1 may be a potential therapeutic target and a prognostic indicator in CRC.

Fusobacterium nucleatum induces chemoresistance in colorectal cancer by inhibiting pyroptosis via the Hippo pathway

ABSTRACT Chemotherapy resistance is one of the main reasons for the poor prognosis of colorectal cancer (CRC). Moreover, dysbiosis of gut bacteria was found to be a specific environmental risk factor. In this study, enrichment of F. nucleatum was elucidated to be significantly associated with CRC recurrence after chemotherapy. Functional experiments showed that F. nucleatum could inhibit pyroptosis induced by chemotherapy drugs, thereby inducing chemoresistance. Furthermore, mechanistic investigation demonstrated that F. nucleatum could regulate the Hippo pathway and promote the expression of BCL2, thereby inhibiting the Caspase-3/GSDME pyroptosis-related pathway induced by chemotherapy drugs and mediating CRC cell chemoresistance. Taken together, these results validated the significant roles of F. nucleatum in CRC chemoresistance, which provided an innovative theoretical basis for the clinical diagnosis and therapy of CRC.

The potential therapeutic effect of melatonin in oxaliplatin combination therapy against chemoresistant colorectal cancer cells.

Oxaliplatin is one of the main therapeutics in colorectal cancer (CRC) chemotherapy. However, in light of multidrug resistance (MDR) phenotype development, the efficacy of oxaliplatin has decreased. This study aimed to assess the potential therapeutic effect of melatonin in oxaliplatin combination therapy for drug-resistant colorectal cancer cells. Initially, the oxaliplatin-resistant cell line was created of LS174T (LS174T/DR) by using the oxaliplatin IC50 concentration and resting cycles. MTT assays and flow cytometry were applied for assessing cell viability and apoptotic cells. The mRNA expression level of Bax, Bcl2, MT1, MT2, and ABCB1 as well as protein levels of ABCB1, Bcl2, BAX were measured by the qRT-PCR and western blot techniques respectively. P-gp activity was assessed by Rho123 staining. The IC50 concentration of oxaliplatin in resistant cells was increased from 500.7 ± 0.2 nM to 7119 ± 0.1 nM. Bcl2, MT1, MT2, and ABCB1 mRNA plus protein expression levels of Bcl2 and ABCB1 were significantly reduced in resistant cells, along with a marked increase in Bax mRNA and protein levels compared to parental cells. Rho 123 staining revealed a marked reduction in P-gp activities in the combination-treated group compared to the oxaliplatin-treated group. The results of cytotoxicity assays, MTT, and flow cytometry revealed that the combination of melatonin and oxaliplatin exerts synergistic effects on induction of oxaliplatin's cytotoxicity in CRC. Our research suggests that combining the treatments of melatonin and oxaliplatin may be considered as a new approach to overcoming oxaliplatin resistance in CRC patients.

Exosomes derived from cancer-associated fibroblasts promote tumorigenesis, metastasis and chemoresistance of colorectal cancer by upregulating circ_0067557 to target Lin28

BackgroundCancer associated fibroblasts (CAFs) can remodel tumor microenvironment by secreting exosomes. This study aimed to investigate the role of exosomes derived from cancer-associated fibroblasts in colorectal cancer (CRC) progression.MethodsCircular RNA (circRNA) array was used to identify differentially expressed circRNAs in exosomes from normal fibroblasts (NFs) and CAFs, and confirmed one differentially expressed circRNA circ_0067557 by real-time PCR. The effect of circ_0067557 on proliferation, metastasis, chemoresistance and apoptosis was verified by wound heal, tranwell, CCK8, sphere-forming and flow cytometry assay.ResultsCirc_0067557 expression in exosomes from CAFs was higher than those from NFs. CAF-derived exosomes promoted the proliferation, migration, invasion and chemoresistance of CRC cells while suppressed apoptosis. Silencing of circ_0067557 inhibited malignant phenotypes of CRC cells by targeting Lin28A and Lin28B. Moreover, CAF-derived exosomes enhanced the growth of CRC xenograft tumors.ConclusionCirc_0067557/Lin28A and Lin28B signal axis may be a potential therapy target for CRC.

5-Fluorouracil resistant CRC cells derived exosomes promote cancer-associated fibroblasts secreting more CXCL12.

Background: Chemoresistance is a key reason for treatment failure in colorectal cancer (CRC) patients. The tumor microenvironment of chemoresistant CRC is distinctly immunosuppressive, although the underlying mechanisms are unclear. Methods: The CRC data sets GSE69657 and GSE62080 were downloaded from the GEO database, and the correlation between TRPC5 and FAP expression was analyzed by Pearson method. The in-situ expression of transient receptor potential channel 5 (TRPC5) and fibroblast activation protein (FAP) in the CRC tissues was examined by immunohistochemistry. TRPC5 expression levels in the HCT8 and HCT116 cell lines and the corresponding 5-fluorouracil (5-FU)-resistant cell lines (HCT8R and HCT116R) were analyzed by western blotting and RT-PCR. Exosomes were isolated from the HCT8R and HCT116R cells and incubated with colorectal normal fibroblasts (NFs), and cancer-associated fibroblasts (CAFs)markers were detected. NFs were also incubated with exosomes isolated from TRPC5-knockdown HCT8R cells, and the changes in intracellular Ca2+ levels and C-X-C motif chemokine ligand 12 (CXCL12) secretion were analyzed. Results: TRPC5 and FAP expression showed positive correlation in the datasets. Immunostaining of CRC tissue specimens further revealed that high TRPC5 and FAP expressions were significantly associated with worse tumor regression. Furthermore, chemoresistant CRC cells expressed higher levels of TRPC5 compared to the chemosensitive cells, and knocking down TRPC5 reversed chemoresistance. Exosomes derived from CRC cells induced the transformation of NFs to CAFs. However, TRPC5-exosomes derived from chemoresistant CRC cells can promote CAFs to secrete more CXCL12. Conclusion: Chemoresistant CRC cells can induce CAFs activation and promote CXCL12 secretion through exosomal TRPC5.

CircPOFUT1 fosters colorectal cancer metastasis and chemoresistance via decoying miR-653-5p/E2F7/WDR66 axis and stabilizing BMI1

CircRNAs are implicated in colorectal cancer (CRC) development and progression. Protein O-fucosyltransferase 1 (POFUT1) plays an oncogenic role via activating Notch1 signaling in CRC. However, the roles of circPOFUT1, which is originated from POFUT1, have not been investigated. Our study showed circPOFUT1 was highly expressed in CRC tissues and cells. CircPOFUT1 enhanced the proliferation, migration and invasion of CRC cells, and promoted tumor growth and liver metastasis invivo. It also reinforced stemness and chemoresistance of CRC cells. Mechanistically, circPOFUT1 regulated the function of E2F7 via sponging miR-653-5p, thereby transcriptionally inducing WDR66 expression and further promoting metastasis in CRC. On the other hand, circPOFUT1 promoted stemness and chemoresistance of CRC cells via stabilizing BMI1 in an IGF2BP1-dependent manner. In conclusion, circPOFUT1 fosters CRC metastasis and chemoresistance via decoying miR-653-5p/E2F7/WDR66 axis and stabilizing BMI1.

The E3 ubiquitin ligase NEDD4 regulates chemoresistance to 5-fluorouracil in colorectal cancer cells by altering JNK signalling

Colorectal cancer (CRC) is the second leading cause of cancer deaths. Though chemotherapy is the main treatment option for advanced CRC, patients invariably acquire resistance to chemotherapeutic drugs and fail to respond to the therapy. Although understanding the mechanisms regulating chemoresistance has been a focus of intense research to manage this challenge, the pathways governing resistance to drugs are poorly understood. In this study, we provide evidence for the role of ubiquitin ligase NEDD4 in resistance developed against the most commonly used CRC chemotherapeutic drug 5-fluorouracil (5-FU). A marked reduction in NEDD4 protein abundance was observed in a panel of CRC cell lines and patient-derived xenograft samples that were resistant to 5-FU. Knockout of NEDD4 in CRC cells protected them from 5-FU-mediated apoptosis but not oxaliplatin or irinotecan. Furthermore, NEDD4 depletion in CRC cells reduced proliferation, colony-forming abilities and tumour growth in mice. Follow-up biochemical analysis highlighted the inhibition of the JNK signalling pathway in NEDD4-deficient cells. Treatment with the JNK activator hesperidin in NEDD4 knockout cells sensitised the CRC cells against 5-FU. Overall, we show that NEDD4 regulates cell proliferation, colony formation, tumour growth and 5-FU chemoresistance in CRC cells.

Cancer-associated fibroblast exosome LINC00355 promotes epithelial-mesenchymal transition and chemoresistance in colorectal cancer through the miR-34b-5p/CRKL axis.

This study was designed to investigate the role and mechanism of cancer-associated fibroblasts (CAFs)-derived exosomes (CAFs-exo) in metastatic and chemoresistant colorectal cancer (CRC). First, CAFs and normal fibroblasts (NFs) were isolated from CRC tissues and histologically normal adjacent tissues. Then, CAFs-exo and NFs-exo were separated with the help of ultracentrifugation. Next, the morphology, diameter and marker expression of exos were evaluated by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA) and western blot, respectively. Besides, real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to detect the expression levels of LINC00355, miR-34b-5p, and CRKL in clinical tissue samples, CRC cells, fibroblasts and exos; MTT assay and cell colony formation assay to assess the chemoresistance and colony formation ability of CRC cells, respectively. Subsequently, the targeting relationship among LINC00355, miR-34b-5p, and CRKL (a target gene of miR-34b-5p) was verified by Luciferase reporter assay; and the binding relationship between LINC00355 and miR-34b-5p was assessed by a pull-down assay. Finally, the expression of epithelial-mesenchymal transition (EMT)-related proteins, and CRKL in cells or exos were detected using western blot. After a series of treatments, CAFs and NFs, CAFs-exo and NFs-exo were successfully isolated and identified. It could be observed that CAFs-exo promoted EMT, colony formation and multidrug resistance in CRC cells by secreting LINC00355. Further studies demonstrated that CAFs-exo-secreted LINC00355 increased the expression of CRKL via inhibiting the expression of miR-34b-5p, thereby enhancing chemoresistance and promoting EMT progression in CRC cells. Collectively, CAFs-exo-derived LINC00355 promotes EMT and chemoresistance in CRC by regulating the miR-34b-5p/CRKL axis.

LAMP2A overexpression in colorectal cancer promotes cell growth and glycolysis via chaperone‑mediated autophagy.

Lysosome-associated membrane protein type 2A (LAMP2A) is a key protein in the chaperone-mediated autophagy (CMA) pathway and has been demonstrated to be involved in the pathogenesis of a number of tumors. However, the role of CMA in colorectal cancer cell proliferation, metastasis and cell survival during oxidative stress and oxaliplatin resistance remains to be elucidated. In the present study, elevated expression of LAMP2A was observed in colon cancer tissues. Then, CMA activity was increased in SW480 and HT29 colorectal cancer cells with a LAMP2A overexpression vector and CMA activity was decreased using a LAMP2A short interfering RNA vector. MTT and colony formation assays showed that the colorectal cancer cell proliferation ability and cell viability following treatment with H2O2 or oxaliplatin were decreased significantly after LAMP2A knockdown and increased significantly after LAMP2A overexpression. Wound healing assays and Transwell invasion assays demonstrated that downregulation of LAMP2A expression inhibited the cell migration and invasion abilities of colorectal cancer and that upregulation of LAMP2A expression promoted cell migration and invasion. Extracellular acidification rate (ECAR) assay and lactate determination assay showed that glycolysis in colorectal cancer cells was significantly downregulated after LAMP2A knockdown and significantly upregulated after LAMP2A overexpression. Inhibition of glycolysis by 2-DG markedly attenuated LAMP2A-induced chemoresistance in colorectal cancer cells. Collectively, these data indicated that CMA can promote colorectal cancer cell proliferation, metastasis and cell survival during oxidative stress and oxaliplatin resistance and that the mechanism is related to the glycolytic pathway, which may provide a new therapeutic target for colorectal cancer patients.

The role of p62 in cell death and survival of 5-fluorouracil and oxaliplatin-resistant colorectal cancer cells.

The protein sequestosome 1 (p62/SQSTM1) is primarily known as a selective autophagy cargo receptor, but due to its multidomain structure, it also has roles in the ubiquitin-proteasome system, metabolism, cell death and survival signalling. The increase in p62 levels is detected in some types of cancers, including colorectal cancer (CRC). Chemoresistance is the main cause of high mortality rates of CRC patients. Since p62 can regulate both cell survival and death, it is a potential modulator of chemoresistance. The impact of p62 on molecular causes of chemoresistance in CRC cells is insufficiently analysed. Therefore, we aimed to determine the impact of p62 on apoptosis, RIPK1-pRIPK3 axis, and IL-8 levels in chemoresistant CRC cells. Our data revealed that p62 levels are higher in the 5-fluorouracil (5-FU)-resistant HCT116/FU subline compared to the parental cell line. 5-FUand oxaliplatin (OxaPt) treatment decreased p62 protein levels and it correlated with chemoresistance of HCT116 and DLD1 cell lines. The silencing of p62 increased CRC cell sensitivity to 5-FU and OxaPt, hence p62 is one of the factors supporting chemoresistance. The downregulation of p62 reduced the activation of caspase-3 and the levels of RIPK1 and pRIPK3. Furthermore, p62 silencing decreased the BAX/BCL2 ratio in the HCT116/FU subline and did not change the levels of apoptosis. Instead, p62 silencing reduced the amount of IL-8 protein. Our results show that p62 impacts chemoresistance by stimulating prosurvival signalling.

Oxaliplatin Enhances the Apoptotic Effect of Mesenchymal Stem Cells, Delivering Soluble TRAIL in Chemoresistant Colorectal Cancer.

A key problem in colorectal cancer (CRC) is the development of resistance to current therapies due to the presence of cancer stem cells (CSC), which leads to poor prognosis. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a protein that activates apoptosis in cancer cells through union with TRAIL death receptors. Cell therapies as delivery systems can produce soluble TRAIL (sTRAIL) and full-length TRAIL (flTRAIL), showing a high capacity to produce apoptosis in vitro and in vivo assays. However, the apoptotic activity of TRAIL as monotherapy had limitations, so it is important to explore other ways to enhance susceptibility to TRAIL. This study evaluated the cytotoxic and proapoptotic activity of soluble TRAIL overexpressed by mesenchymal stem cells (MSC) in an oxaliplatin-resistant CRC cell line. Bone marrow-MSC were lentiviral transduced for soluble TRAIL expression. DR5 death receptor expression was determined in Caco-2 and CMT-93 CRC cell lines. Sensitivity to first-line chemotherapies and recombinant TRAIL was evaluated by half-maximal inhibitory concentrations. Cytotoxic and proapoptotic activity of soluble TRAIL-MSC alone and combined with chemotherapy pre-treatment was evaluated using co-cultures. Caco-2 and CMT-93 cell lines expressed 59.08 ± 5.071 and 51.65 ± 11.99 of DR5 receptor and had IC50 of 534.15 ng/mL and 581.34 ng/mL for recombinant murine TRAIL (rmTRAIL), respectively. This finding was classified as moderate resistance to TRAIL. The Caco-2 cell line showed resistance to oxaliplatin and irinotecan. MSC successfully overexpressed soluble TRAIL and induced cancer cell death at a 1:6 ratio in co-culture. Oxaliplatin pre-treatment in the Caco-2 cell line increased the cell death percentage (50%) and apoptosis by sTRAIL. This finding was statistically different from the negative control (p < 0.05), and activity was even higher with the oxaliplatin-flTRAIL combination. Thus, oxaliplatin increases apoptotic activity induced by soluble TRAIL in a chemoresistant CRC cell line.

Targeting survivin with Tanshinone IIA inhibits tumor growth and overcomes chemoresistance in colorectal cancer

The inhibitor of apoptosis protein survivin has a critical regulatory role in carcinogenesis and treatment tolerance in colorectal cancer (CRC). However, the targeted drugs for survivin protein are extremely limited. In the present research, we discovered that Tanshinone IIA (Tan IIA) played a dual regulatory role in inhibiting tumorigenesis and reversing 5-Fu tolerance via modulating the expression and phosphorylation of survivin in CRC cells. Mechanistically, Tan IIA suppressed the Akt/WEE1/CDK1 signaling pathway, which led to the downregulation of survivin Thr34 phosphorylation and destruction of the interaction between USP1 and survivin to promote survivin ubiquitination and degradation. Furthermore, Tan IIA significantly facilitated chemoresistant CRC cells to 5-Fu sensitivity. These results revealed that Tan IIA possessed a strong antitumor activity against CRC cells and could act as an up-and-coming agent for treating CRC and overcoming chemotherapy resistance.

MiR-653-3p promotes genomic instability of colorectal cancer cells via targeting SIRT1/TWIST1 signaling pathway

Development of colorectal cancer (CRC) accompanied with genomic instability. Genomic instability was promoted by microRNAs (miRNAs) inhibiting key genes in DNA damage repair and spindle assembly processes. Whether miR-653-3p affects genomic instability is unknown. The aim of this study is to explore the effect of miR-653-3p on genomic instability in CRC cells. Based on RT-qPCR analysis, miR-653-3p was highly expressed in CRC cells. Through single-cell electrophoresis assay and chromosome karyotype analysis, we determined ectopic expression of miR-653-3p induced increased DNA damage but inhibited apoptosis by promoting chromosomal instability. Mechanistically, luciferase assay identified the direct interaction of miR-653-3p with the 3′ UTR of SIRT1, and western blot analysis indicated miR-653-3p inhibited SIRT1 and then promoted STAT3 phosphorylation and TWIST1 expression. The results of karyotype analysis showed that the upregulation of SIRT1 and the downregulation of TWIST1 caused by the downregulation of miR-653-3p suppressed chromosomal instability. Additionally, our evidence showed that miR-653-3p promoted CRC cell proliferation, migration, and 5-FU resistance, and miR-653-3p induced the development of CRC in the xenograft mice model. Altogether, our evidence suggests that miR-653-3p regulates SIRT1/TWIST1 signaling pathway and plays an important role in promoting genomic instability, proliferation, migration, and chemoresistance of CRC cells, which may serve as a promising therapeutic target for CRC therapy.

Anastasis enhances metastasis and chemoresistance of colorectal cancer cells through upregulating cIAP2/NFκB signaling

Chemotherapy is a common strategy to treat cancer. However, acquired resistance and metastasis are the major obstacles to successful treatment. Anastasis is a process by which cells survive executioner caspase activation when facing apoptotic stress. Here we demonstrate that colorectal cancer cells can undergo anastasis after transient exposure to chemotherapeutic drugs. Using a lineage tracing system to label and isolate cells that have experienced executioner caspase activation in response to drug treatment, we show that anastasis grants colorectal cancer cells enhanced migration, metastasis, and chemoresistance. Mechanistically, treatment with chemotherapeutic drugs induces upregulated expression of cIAP2 and activation of NFκB, which are required for cells to survive executioner caspase activation. The elevated cIAP2/NFκB signaling persists in anastatic cancer cells to promote migration and chemoresistance. Our study unveils that cIAP2/NFκB-dependent anastasis promotes acquired resistance and metastasis after chemotherapy.

Proteomic profiling of FOLFOX-resistant colorectal cancer cells.

e15588 Background: Chemoresistance is a major cause of colorectal cancer (CRC) mortality. Although multidrug regimen has been established as the backbone of CRC chemotherapy for better treatment efficacy, chemoresistance is common among late-stage CRC. Proteomic profiling of both the chemoresistant and wild-type CRC cells may provide hints for the mechanisms of chemoresistance and suggest targets for improving chemotherapy efficacy. Methods: Human CRC cell lines (DLD-1 and HCT-116) were treated with progressively increased dosage of FOLFOX (5-flurouracil (5-FU), folinic acid (LEU) and oxaliplatin (OXA)) to develop chemoresistance as DLD-1-R and HCT-116-R respectively. After confirmation of the successful development of chemoresistance by Cell Counting Kit-8 test (CCK-8), the comparison of cell samples between chemoresistant and wild-type cell lines were conducted by proteomic profiling using quantitative mass spectrometry (MS)-based techniques. MS and MS/ MS peptides spectra were analysed by Progenesis QI for proteomics software compared with Swiss-Prot dataset. Differentially expressed proteins (DEP) are defined as -1 &gt; log2FC &gt; 1, p &lt; 0.05. Gene-list enrichment by Enrichr (https://maayanlab.cloud/Enrichr/) was employed for identifying the hallmark gene sets of the significantly enriched molecular processes and pathways of each group. All experiments were performed with at least 3 replications. Results: The development of FOLFOX-resistance took one year. The highest drug concentrations achieved were 0.5mM 5-FU, 50µM LEU, and 50µM OXA for DLD-1-R, and 5µM 5-FU, 0.5µM LEU, and 0.5µM OXA for HCT-116-R. The chemoresistance was found to be 14.73 (DLD-1-R) and 1.61 (HCT-116-R) times of the wild-type DLD-1 and HCT-116 respectively from CCK-8 tests. A total of 345 DEP with 154 up-regulated and 191 down-regulated proteins were found in DLD-1-R. While a total of 95 DEP with 66 up-regulated and 29 down-regulated proteins were found in HCT-116-R. Gene ontology molecular process (2021) analyses found that cadherin binding were significantly enriched in both DLD-1-R and HCT-116-R (Adjusted p-value &lt; 0.05). KEGG pathway (2021) analysis found that oxidative phosphorylation, regulation of actin cytoskeleton and HIF-1 signalling pathway are among the significantly enriched pathways in DLD-1-R (Adjusted p value &lt; 0.05). There was no significantly enriched pathway found in HCT-116-R in the same analysis. Conclusions: Our study has successfully established CRC cells with chemoresistance to the FOLFOX regimen. Proteomic profiling has found the cadherin binding as the significantly altered molecular process along with several important signalling pathways in chemoresistant CRC cells. These findings could suggest new directions in the development of anti-chemoresistance strategies of CRC.

KIAA1549 promotes the development and chemoresistance of colorectal cancer by upregulating ERCC2.

Colorectal cancer (CRC) is the third most commonly diagnosed cancer worldwide. Chemotherapy is the mainstay of treatment for patients with CRC in II-IV stages. Resistance to chemotherapy occurs commonly, which results in treatment failure. Therefore, the identification of novel functional biomarkers is essential for recognizing high-risk patients, predicting recurrence, and developing new therapeutic strategies. Herein, we assessed the roles of KIAA1549 in promoting tumor development and chemoresistance in colorectal cancer. As a result, we found that KIAA1549 expression is up-regulation in CRC. Public databases revealed a progressive up-regulation of KIAA1549 expression from adenomas to carcinomas. Functional characterization uncovered that KIAA1549 promotes tumor malignant phenotypes and boosts the chemoresistance of CRC cells in an ERCC2-dependent manner. Inhibition of KIAA1549 and ERCC2 effectively enhanced the sensitivity to chemotherapeutic drugs oxaliplatin and 5-fluorouracil. Our findings suggest that endogenous KIAA1549 might function as a tumor development-promoting role and trigger chemoresistance in colorectal cancer partly by upregulating DNA repair protein ERCC2. Hence, KIAA1549 could be an effective therapeutic target for CRC and inhibition of KIAA1549 combined with chemotherapy might be a potential therapeutic strategy in the future.

FAP promotes metastasis and chemoresistance via regulating YAP1 and macrophages in mucinous colorectal adenocarcinoma

Mucinous colorectal adenocarcinoma (MC) is less likely to respond to chemotherapy and is associated with poorer prognosis compared with non-MC (NMC). Fibroblast activation protein (FAP) was found and validated to be upregulated in MC patients and was negatively correlated with prognosis and therapeutic outcomes in colorectal cancer (CRC) patients who were treated with adjuvant chemotherapy. Overexpression of FAP promoted CRC cell growth, invasion and metastasis, and enhanced chemoresistance. Myosin phosphatase Rho-interacting protein (MPRIP) was identified as a direct interacting protein of FAP. FAP may influence the efficiency of chemotherapy and prognosis by promoting the crucial functions of CRC and inducing tumor-associated macrophages (TAMs) recruitment and M2 polarization through regulating theRas Homolog Family Member/Hippo/Yes-associated protein (Rho/Hippo/YAP) signaling pathway. Knockdown of FAP could reverse tumorigenicity and chemoresistance in CRC cells. Thus, FAP may serve as a marker for prognosis and therapeutic outcome, as well as a potential therapeutic target to overcome chemoresistance in MC patients.

CCAT 1- A Pivotal Oncogenic Long Non-Coding RNA in Colorectal Cancer.

Colorectal cancer (CRC) is ranked as the third most common cancer and second deadliest cancer in both men and women in the world. Currently, the cure rate and 5-year survival rate of CRC patients remain relatively low. Therefore, discovering a novel molecular biomarker that can be used to improve CRC screening, diagnosis, prognosis, and treatment would be beneficial. Long non-coding RNA colon cancer-associated transcript 1 (CCAT 1) has been found overexpressed in CRC and is associated with CRC tumorigenesis and treatment outcome. CCAT 1 has a high degree of specificity and sensitivity, it is readily detected in CRC tissues and is significantly overexpressed in both premalignant and malignant CRC tissues. Besides, CCAT 1 is associated with clinical manifestation and advanced features of CRC, such as lymph node metastasis, high tumor node metastasis stage, differentiation, invasion, and distant metastasis. In addition, they can upregulate oncogenic c-MYC and negatively modulate microRNAs via different mechanisms of action. Furthermore, dysregulated CCAT 1 also enhances the chemoresistance in CRC cells while downregulation of them reverses the malignant phenotypes of cancer cells. In brief, CCAT 1 serves as a potential screening, diagnostic and prognostic biomarker in CRC, it also serves as a potential therapeutic marker to treat CRC patients.

STAT3 regulates 5-Fu resistance in human colorectal cancer cells by promoting Mcl-1-dependent cytoprotective autophagy.

Chemoresistance to 5-fluorouracil (5-Fu)-based chemotherapy is one of the primary reasons for the failure of colorectal cancer (CRC) management. STAT3 can mediate tumor drug resistance through a variety of diverse mechanisms. Nonetheless, the underlying mechanisms of STAT3-induced 5-Fu resistance in CRC are still poorly understood. Here, we aimed to investigate the potential mechanism(s) of STAT3-induced 5-Fu resistance in CRC. Quantitative RT-PCR and Western blot were used to test the expression of STAT3 and Mcl-1 in chemosensitive and chemoresistant CRC tissues and cell lines. After overexpression or knockdown of STAT3 or Mcl-1, and/or treatment with or without 5-Fu or chloroquine (CQ), we tested cell viability, inhibitory concentration 50% (IC50 ) value of 5-FU, cell apoptosis, proliferation, migration, and autophagy. STAT3 and Mcl-1 were significantly upregulated in the chemoresistant CRC tissues and cell lines, and STAT3 positively regulated Mcl-1. Functional studies demonstrated that STAT3 promoted 5-Fu resistance in CRC. Mechanistically, STAT3 triggered autophagy via Mcl-1 to induce cancer chemoresistance. Our results show that STAT3 regulates 5-Fu resistance in CRC by promoting Mcl-1-dependent cytoprotective autophagy. Our results provide a novel role of STAT3 and may offer a new approach for managing CRC 5-Fu resistance.

Resveratrol Modulates Chemosensitisation to 5-FU via β1-Integrin/HIF-1α Axis in CRC Tumor Microenvironment.

Frequent development of resistance to chemotherapeutic agents such as 5-flourouracil (5-FU) complicates the treatment of advanced colorectal cancer (CRC). Resveratrol is able to utilize β1-integrin receptors, strongly expressed in CRC cells, to transmit and exert anti-carcinogenic signals, but whether it can also utilize these receptors to overcome 5-FU chemoresistance in CRC cells has not yet been investigated. Effects of β1-integrin knockdown on anti-cancer capabilities of resveratrol and 5-FU were investigated in HCT-116 and 5-FU-resistant HCT-116R CRC tumor microenvironment (TME) with 3D-alginate as well as monolayer cultures. Resveratrol increased CRC cell sensitivity to 5-FU by reducing TME-promoted vitality, proliferation, colony formation, invasion tendency and mesenchymal phenotype including pro-migration pseudopodia. Furthermore, resveratrol impaired CRC cells in favor of more effective utilization of 5-FU by down-regulating TME-induced inflammation (NF-kB), vascularisation (VEGF, HIF-1α) and cancer stem cell production (CD44, CD133, ALDH1), while up-regulating apoptosis (caspase-3) that was previously inhibited by TME. These anti-cancer mechanisms of resveratrol were largely abolished by antisense oligonucleotides against β1-integrin (β1-ASO) in both CRC cell lines, indicating the particular importance of β1-integrin receptors for the 5-FU-chemosensitising effect of resveratrol. Lastly, co-immunoprecipitation tests showed that resveratrol targets and modulates the TME-associated β1-integrin/HIF-1α signaling axis in CRC cells. Our results suggest for the first time the utility of the β1-integrin/HIF-1α signaling axis related to chemosensitization and overcoming chemoresistance to 5-FU in CRC cells by resveratrol, underlining its potential supportive applications in CRC treatment.