Chemoresistance In Colorectal Cancer Research Articles

Targeting EGFR sensitizes 5-Fu-resistant colon cancer cells through modification of the lncRNA-FGD5-AS1-miR-330-3p-Hexokinase 2 axis

5-Fluorouracil (5-Fu) is a widely applied anti-cancer agent against colorectal cancer (CRC), yet a number of CRC patients have developed resistance to 5-Fu-based chemotherapy. The epidermal growth factor receptor (EGFR) is recognized as an oncogene that promotes diverse cancer progresses. In addition, long noncoding RNAs (lncRNAs) are essential regulators of cancers. Here we report that EGFR and lncRNA-FGD5-AS1 promoted 5-Fu resistance of CRC. By establishing the 5-Fu-resistant CRC cell line, we detected that EGFR, FGD5-AS1, and glucose metabolism were significantly elevated in 5-Fu-resistant CRC cells. A microRNA-microarray analysis revealed that miR-330-3p functions as a downstream effector of FGD5-AS1. FGD5-AS1 directly sponged miR-330-3p to form a competing endogenous RNA (ceRNA) network, leading to inhibition of miR-330-3p expression. Furthermore, bioinformatics analysis revealed that Hexokinase 2 (HK2) was a potential target of miR-330-3p, which was validated by luciferase assay. Rescue experiments demonstrated that FGD5-AS1 promotes glycolysis through modulating the miR-330-3p-HK2 axis, leading to 5-Fu resistance of CRC cancer cells. Finally, in vitro and in vivo xenograft experiments consistently demonstrated that inhibition of EGFR by the specific inhibitor erlotinib effectively enhanced the anti-tumor toxicity of 5-Fu by targeting the EGFR-FGD5-AS1-miR-330-3p-HK2 pathway. In summary, this study demonstrates new mechanisms of the EGFR-modulated 5-Fu resistance through modulating the noncoding RNA network, contributing to development of new approaches against chemoresistant CRC.

Abstract 1405: Colorectal carcinogenesis in Smad4/SPTBN1 mutants alter the intestinal microbiome and resistance to 5FU

Abstract Background/Aims: Emerging data shows a rise in colorectal cancer (CRC) incidence in young men and women that is often chemoresistant, with potential new risk factors including alterations in the microbiome that remain understudied. We have recently observed altered microbiome with modulation of the gut immune response through crosstalk between sensors, microbes, and the TGF-β signaling pathway. Interestingly, we observed that human CRC cell lines with disruption of TGF-β had increased sensitivity to cisplatin and other DNA cross-linking agents. Yet at the same time, human CRC with loss of Smad4 portends poor prognosis and resistance to chemotherapy. Therefore, it was unclear whether the epithelial loss of Smad4 or stromal loss of Smad4 expression could be responsible for chemoresistance. Here, we investigated the role of chemotherapy with disruption of TGF-β signaling and an altered intestinal microbiome in colorectal carcinogenesis. Methods: CRCs induced by azoxymethane (AOM)/dextran sodium sulfate (DSS) in wild type (WT) and TGF-β signaling deficient mice (SKO: Smad4+/- and Smad4+/-/Sptbn1+/-) were treated with 5-Fluoro-Uracil (5FU). Shotgun metagenomic sequencing was performed in fecal samples from WT and SKO mice before and after treatment. Results: Our analyses revealed that SKO mice are more susceptible to AOM/DSS induced CRC as demonstrated by increased multiplicity (SKO vs WT: 10.25±1.5 vs 5.5±1.4, p=0.01) and tumor size (SKO vs WT: 3.63±0.7mm vs 2.17±0.3mm, p=0.02). CRC that develops in mice with disrupted TGF-β signaling is chemoresistance to 5FU and progress to liver metastasis confirmed by histological and immunohistochemical analysis. Interestingly, SKO mice display a unique gut microbiome signature compared to the WT mice. SKO mice had significantly reduced abundances of beneficial species of B. vulgutus (0.056±0.0078 vs 0.018±0.0052) and P. distasonis (0.007±0.001 vs 0.003±0.001). In addition to E. Boltae, and Mordavella sp., the relative abundance of Bacteroides was significantly reduced in AOM/DSS induced tumors and recovered to basal levels after 5FU treatment in WT mice but not in SKO mice with deficient TGF-β signaling (e.g. Bacteroides dorei: WT basal vs WT-CRC vs WT-CRC-5FU: 0.28±0.08 vs 0.05 ±0.01 vs 0.45±0.17; SKO basal vs SKO CRC vs SKO-CRC-5FU: 0.13±0.02 vs 0.06 ±0.007 vs 0.07±0.01). Conclusions: Our study identified unique gut microbiome species corresponding to 5FU resistance through interactions with key immune-related pathways such as TGF-β members that are implicated in CRC development and drug resistance. The in vivo studies suggest a cell non-autonomous role of the TGF-β pathway in CRC chemoresistance. Collectively, the altered microbiome composition from impaired TGF-β signaling could promote colorectal carcinogenesis and drug resistance. Manipulating these specific species associated with 5FU could potentially increase drug response. Citation Format: Shuyun Rao, Zhuanhuai Wang, Xiaochun Yang, Lindsay M. Hopson, Stephanie S. Singleton, Wilma Jogunoori, Raja Mazumder, Vincent Obias, Paul Lin, Bao-Ngoc Nguyen, Michael Yao, Larry Miller, Jon White, Lopa Mishra. Colorectal carcinogenesis in Smad4/SPTBN1 mutants alter the intestinal microbiome and resistance to 5FU [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1405.

MicroRNA-29b-3p promotes 5-fluorouracil resistance via suppressing TRAF5-mediated necroptosis in human colorectal cancer.

Drug resistance in colorectal cancer is a great challenge in clinic. Elucidating the deep mechanism underlying drug resistance will bring much benefit to diagnosis, therapy and prognosis in patients with colorectal cancer. In this study, miR-29b-3p was shown to be involved in resistance to 5-fluorouracil (5-FU)-induced necroptosis of colorectal cancer. Further, miR-29b-3p was shown to target a regulatory subunit of necroptosis TRAF5. Rescue of TRAF5 could reverse the effect of miR-29b-3p on 5-FU-induced necroptosis, which was consistent with the role of necrostatin-1 (a specific necroptosis inhibitor). Then it was demonstrated that miR-29b-3p was positively correlated with chemoresistance in colorectal cancer while TRAF5 negatively. In conclusion, it is deduced that miR-29b-3p/TRAF5 signaling axis plays critical role in drug resistance in chemotherapy for colorectal cancer patients by regulating necroptosis. The findings in this study provide us a new target for interfere therapy in colorectal cancer.

FXYD6 Regulates Chemosensitivity by Mediating the Expression of Na+/K+-ATPase α1 and Affecting Cell Autophagy and Apoptosis in Colorectal Cancer.

Purpose Chemoresistance is a challenge of improving chemotherapeutic efficacy and prolonging survival time for patients with colorectal cancer (CRC); it is the major cause of frequent recurrence, rapid metastasis, and poor prognosis for CRC patients. FXYD6 is a regulator of Na+/K+-ATPase which is depressed in chemoresistant CRC patients. However, the biological roles of FXYD6 on regulating chemoresistance in CRC are still unclear. Methods GSE3964 and GSE69657 from GEO DataSets were used to analyze the relationship of genes and chemoresistance. The FXYD6 expression level was detected by western blotting and real-time PCR and also analyzed from TCGA DataSet. To investigate the functional role of FXYD6 and ATP-α1, FXYD6 and ATP-α1 functional cell models were constructed. Drug sensitivity and cell proliferation were performed by MTT assay. Autophagy and apoptosis were conducted by autophagy fluorescence analysis and flow cytometric analysis, respectively. Autophagy and apoptosis markers were tested by western blotting. Results FXYD6 was downregulated in CRC resistant patients and irinotecan- (Iri-) resistant SW620 cells (SW620/Iri). FXYD6 silence inhibited cell apoptosis and enhanced prosurvival autophagy, whereas FXYD6 overexpression produced the opposite effect which alleviated the drug resistance to irinotecan and oxaliplatin of CRC cells. FXYD6 regulates chemosensitivity by mediating the expression of Na+/K+-ATPase α1 and affecting cell autophagy and apoptosis in colorectal cancer. Conclusion FXYD6 functions as a chemosensitivity regulator which may predict the curative effect of chemotherapy in colorectal cancer.

The loss of SHMT2 mediates 5-fluorouracil chemoresistance in colorectal cancer by upregulating autophagy

5-Fluorouracil (5-FU)-based chemotherapy is the first-line treatment for colorectal cancer (CRC) but is hampered by chemoresistance. Despite its impact on patient survival, the mechanism underlying chemoresistance against 5-FU remains poorly understood. Here, we identified serine hydroxymethyltransferase-2 (SHMT2) as a critical regulator of 5-FU chemoresistance in CRC. SHMT2 inhibits autophagy by binding cytosolic p53 instead of metabolism. SHMT2 prevents cytosolic p53 degradation by inhibiting the binding of p53 and HDM2. Under 5-FU treatment, SHMT2 depletion promotes autophagy and inhibits apoptosis. Autophagy inhibitors decrease low SHMT2-induced 5-FU resistance in vitro and in vivo. Finally, the lethality of 5-FU treatment to CRC cells was enhanced by treatment with the autophagy inhibitor chloroquine in patient-derived and CRC cell xenograft models. Taken together, our findings indicate that autophagy induced by low SHMT2 levels mediates 5-FU resistance in CRC. These results reveal the SHMT2–p53 interaction as a novel therapeutic target and provide a potential opportunity to reduce chemoresistance.

Roles of kinesin superfamily proteins in colorectal cancer carcinogenesis (Review).

Colorectal cancer (CRC), a commonly occurring carcinoma, now ranks the second in terms of cancer‑associated deaths around the world. Among the numerous factors that contribute to CRC tumor progression, a class of motor proteins known as the kinesins has been found to play a vital role. Kinesins are responsible for the intracellular trafficking of functional proteins, organelles and biomacromolecules along microtubules. Dysregulation of kinesins has been revealed to influence the cell cycle to cause abnormal cell growth and affect cell adhesion to promote epithelial‑mesenchymal transition in breast, bladder, ovarian and prostate cancer. Studies on the function of kinesins in CRC have also been performed, although, to the best of our knowledge, little is known about the underlying mechanisms of kinesins in CRC progression. The present review outlines the roles played by different kinesins in CRC carcinogenesis, mainly discussing the most studied subfamilies (kinesin3‑6, 8, 10, 11 and 13), This review aims to illustrate the functions of kinesins in CRC cell growth, cancer metastasis and chemoresistance to provide insights regarding kinesins as potential targets for determining CRC prognosis and selecting therapy.

The ZEB2-dependent EMT transcriptional programme drives therapy resistance by activating nucleotide excision repair genes ERCC1 and ERCC4 in colorectal cancer.

Resistance to adjuvant chemotherapy is a major clinical problem in the treatment of colorectal cancer (CRC). The aim of this study was to elucidate the role of an epithelial to mesenchymal transition (EMT)‐inducing protein, ZEB2, in chemoresistance of CRC, and to uncover the underlying mechanism. We performed IHC for ZEB2 and association analyses with clinical outcomes on primary CRC and matched CRC liver metastases in compliance with observational biomarker study guidelines. ZEB2 expression in primary tumours was an independent prognostic marker of reduced overall survival and disease‐free survival in patients who received adjuvant FOLFOX chemotherapy. ZEB2 expression was retained in 96% of liver metastases. The ZEB2‐dependent EMT transcriptional programme activated nucleotide excision repair (NER) pathway largely via upregulation of the ERCC1 gene and other components in NER pathway, leading to enhanced viability of CRC cells upon oxaliplatin treatment. ERCC1‐overexpressing CRC cells did not respond to oxaliplatin in vivo, as assessed using a murine orthotopic model in a randomised and blinded preclinical study. Our findings show that ZEB2 is a biomarker of tumour response to chemotherapy and risk of recurrence in CRC patients. We propose that the ZEB2‐ERCC1 axis is a key determinant of chemoresistance in CRC.

SOX2 promotes chemoresistance, cancer stem cells properties, and epithelial\u2013mesenchymal transition by \u03b2-catenin and Beclin1/autophagy signaling in colorectal cancer

Sex-determining region Y-box2 (SOX2), a master regulator of embryonic and induced pluripotent stem cells, drives cancer stem cells (CSCs) properties, fuels tumor initiation, and contributes to tumor aggressiveness. Our previous study has demonstrated the oncogenic role of SOX2 in colorectal cancer (CRC). In this study, we sought to elucidate the underlying mechanisms. Cell function experiments were performed to detect chemoresistance, proliferation, stemness, migration, and invasion in vitro. Chromatin immunoprecipitation, co-immunoprecipitation, luciferase reporter assay, and immunofluorescence were performed to explore the regulation of ABCC2, β-catenin, and Beclin1 by SOX2. The carcinogenic role of SOX2-β-catenin/Beclin1-ABCC2 axis in vivo was analyzed by CRC tissues and xenograft models. Here, we reported that SOX2 sustained chemoresistance by transcriptional activation of ABCC2 expression. Suppressing either β-catenin or autophagy signaling curbed SOX2-driven chemoresistance, stemness, and epithelial–mesenchymal transition (EMT). Mechanistically, SOX2 combined with β-catenin and increased its nuclear expression and transcriptional activity. Transcriptional activation of Beclin1 expression by SOX2 consequently activating autophagy and inducing malignant phenotype. Furthermore, overexpression of β-catenin or Beclin1 facilitated ABCC2 expression. The clinical analyses showed that high expression of ABCC2 and Beclin1 were positively correlated with SOX2 and were associated with poor prognosis in CRC patients. Finally, xenograft models revealed that inhibition of SOX2 expression and autophagy restrained tumor growth and chemoresistance in vivo. Conclusively, we demonstrated a novel mechanism by which the SOX2-β-catenin/Beclin1/autophagy signaling axis regulates chemoresistance, stemness, and EMT in CRC. Our findings provide novel insights into CRC carcinogenesis and may help develop potential therapeutic candidates for CRC.

Exosome-Mediated Transfer of circ_0000338 Enhances 5-Fluorouracil Resistance in Colorectal Cancer through Regulating MicroRNA 217 (miR-217) and miR-485-3p.

Exosomes are microvesicles secreted by body cells for intercellular communication. The circular RNA circ_0000338 was found to be present in extracellular vesicles and improve the chemoresistance of colorectal cancer (CRC) cells. However, the role of exosomal circ_0000338 in 5-fluorouracil (5-FU) resistance in CRC is largely unknown. The levels of circ_0000338, microRNA 217 (miR-217), and miR-485-3p were detected using quantitative real-time PCR (qRT-PCR). The 50% inhibitory concentration (IC50) values of cells for 5-FU, cell proliferation, and apoptosis were evaluated using cell counting kit 8 (CCK-8), colony formation, flow cytometry, and Western blot assays. The interaction between miR-217 or miR-485-3p and circ_0000338 was confirmed by RNA immunoprecipitation (RIP), dual-luciferase reporter, and pulldown assays. Exosomes were isolated by ultracentrifugation and qualified by transmission electron microscopy (TEM), Nanosight tracking analysis (NTA), and Western blotting. Xenograft models were performed to analyze whether circ_0000338-loaded exosomes could increase resistance of CRC cells to 5-FU in vivo The circ_0000338 level was elevated in 5-FU-resistant CRC tissues and cells, and circ_0000338 knockdown sensitized 5-FU-resistant CRC cells to 5-FU through enhancing apoptosis and decreasing proliferation in vitro Mechanistically, circ_0000338 directly bound to miR-217 and miR-485-3p, and the inhibition of miR-217 or miR-485-3p reversed the effects of circ_0000338 knockdown on cell 5-FU resistance in CRC. Additionally, extracellular circ_0000338 could be incorporated into secreted exosomes and transmitted to 5-FU-sensitive cells. Treatment-sensitive cells with exosomes containing circ_0000338 reduced the 5-FU response in CRC both in vitro and in vivo Besides that, the exosomal circ_0000338 concentration was higher in patients exhibiting resistance to 5-FU and showed good diagnostic efficiency in 5-FU-resistant CRC. The delivery of circ_0000338 via exosomes enhanced 5-FU resistance in CRC through negative regulation of miR-217 and miR-485-3p, indicating a promising diagnostic and therapeutic marker for 5-FU-based chemotherapy in CRC patients.

Olaparib-mediated enhancement of 5-fluorouracil cytotoxicity in mismatch repair deficient colorectal cancer cells

BackgroundThe advances in colorectal cancer (CRC) treatment include the identification of deficiencies in Mismatch Repair (MMR) pathway to predict the benefit of adjuvant 5-fluorouracil (5-FU) and oxaliplatin for stage II CRC and immunotherapy. Defective MMR contributes to chemoresistance in CRC. A growing body of evidence supports the role of Poly-(ADP-ribose) polymerase (PARP) inhibitors, such as Olaparib, in the treatment of different subsets of cancer beyond the tumors with homologous recombination deficiencies. In this work we evaluated the effect of Olaparib on 5-FU cytotoxicity in MMR-deficient and proficient CRC cells and the mechanisms involved.MethodsHuman colon cancer cell lines, proficient (HT29) and deficient (HCT116) in MMR, were treated with 5-FU and Olaparib. Cytotoxicity was assessed by MTT and clonogenic assays, apoptosis induction and cell cycle progression by flow cytometry, DNA damage by comet assay. Adhesion and transwell migration assays were also performed.ResultsOur results showed enhancement of the 5-FU citotoxicity by Olaparib in MMR-deficient HCT116 colon cancer cells. Moreover, the combined treatment with Olaparib and 5-FU induced G2/M arrest, apoptosis and polyploidy in these cells. In MMR proficient HT29 cells, the Olaparib alone reduced clonogenic survival, induced DNA damage accumulation and decreased the adhesion and migration capacities.ConclusionOur results suggest benefits of Olaparib inclusion in CRC treatment, as combination with 5-FU for MMR deficient CRC and as monotherapy for MMR proficient CRC. Thus, combined therapy with Olaparib could be a strategy to overcome 5-FU chemotherapeutic resistance in MMR-deficient CRC.

Sec62 promotes stemness and chemoresistance of human colorectal cancer through activating Wnt/\u03b2-catenin pathway

BackgroundCancer stem cell (CSC)-related chemoresistance leads to poor outcome of the patients with colorectal cancer (CRC). In this study, we identified the chemoresistance-relevant molecules and decipher the involved mechanisms to provide potential therapeutic target for CRC. We focused on Sec62, a novel target with significantly increased expression in chemoresistant CRC tissues, and further investigated its role in the progression of CRC.MethodsThrough analyzing the differentially-expressed genes between chemoresistant and chemosensitive CRCs, we selected Sec62 as a novel chemoresistance-related target in CRC. The expression and clinical significance of Sec62 were determined by immunoblotting and immunohistochemistry in tissues and cell lines of CRC. The roles of Sec62 in drug resistance, stemness and tumorigenesis were evaluated in vitro and in vivo using functional experiments. GST pull-down, western blot, coimmunoprecipitation and Me-RIP assays were performed to further explore the downstream molecular mechanisms.ResultsSec62 upregulation was associated with the chemoresistance of CRC and poor outcome of CRC patients. Depletion of Sec62 sensitized CRC cells to chemotherapeutic drugs. Sec62 promoted the stemness of CRC cells through activating Wnt/β-catenin signaling. Mechanistically, Sec62 bound to β-catenin and inhibited the degradation of β-catenin. Sec62 competitively disrupted the interaction between β-catenin and APC to inhibit the β-catenin destruction complex assembly. Moreover, Sec62 expression was upregulated by the m6A-mediated stabilization of Sec62 mRNA.ConclusionsSec62 upregulated by the METTL3-mediated m6A modification promotes the stemness and chemoresistance of CRC by binding to β-catenin and enhancing Wnt signalling. Thus, m6A modification-Sec62-β-catenin molecular axis might act as therapeutic targets in improving treatment of CRC.

Repositioning metformin and propranolol for colorectal and triple negative breast cancers treatment

Drug repositioning refers to new uses for existing drugs outside the scope of the original medical indications. This approach fastens the process of drug development allowing finding effective drugs with reduced side effects and lower costs. Colorectal cancer (CRC) is often diagnosed at advanced stages, when the probability of chemotherapy resistance is higher. Triple negative breast cancer (TNBC) is the most aggressive type of breast cancer, highly metastatic and difficult to treat. For both tumor types, available treatments are generally associated to severe side effects. In our work, we explored the effect of combining metformin and propranolol, two repositioned drugs, in both tumor types. We demonstrate that treatment affects viability, epithelial-mesenchymal transition and migratory potential of CRC cells as we described before for TNBC. We show that combined treatment affects different steps leading to metastasis in TNBC. Moreover, combined treatment is also effective preventing the development of 5-FU resistant CRC. Our data suggest that combination of metformin and propranolol could be useful as a putative adjuvant treatment for both TNBC and CRC and an alternative for chemo-resistant CRC, providing a low-cost alternative therapy without associated toxicity.

LncRNA XIST/miR-137 axis strengthens chemo-resistance and glycolysis of colorectal cancer cells by hindering transformation from PKM2 to PKM1.

Glycolysis was an essential driver of chemo-resistance in colorectal cancer (CRC), albeit with limited molecular explanations. We strived to elucidate the involvement of lncRNA XIST/miR-137/PKM axis in chemo-tolerance and glycolysis of CRC. Altogether 212 pairs of tumor tissues and adjacent normal tissues were collected from CRC patients. Moreover, human CRC epithelial cell lines, including HT29, SW480, SW620 and LoVo, were purchased in advance, and their activity was estimated after transfection of si-XIST or miR-137 mimic. Furthermore, 5-FU/cisplatin-resistance of CRC cells was determined through MTT assay, and glycolytic potential of CRC cells was appraised based on oxygen consumption rate (OCR) and extracellular acidification rate (ECAR). Highly-expressed XIST were predictive of severe symptoms and unfavorable 3-year survival of CRC patients (P< 0.05). Besides, silencing of XIST not only diminished proliferative, migratory and invasive power of CRC cells (P< 0.05), but also enhanced sensitivity of CRC cells responding to 5-FU/cisplatin (P< 0.05). Glycolytic potency of CRC cells was also undermined by si-XIST, with decreased maximal respiration and maximal glycolytic capacity in the si-XIST group as relative to NC group (P< 0.05). Nevertheless, miR-137 mimic attenuated the facilitating effect of pcDNA3.1-XIST on proliferation, migration, invasion, 5-FU/cisplatin-resistance and glycolysis of CRC cells (P< 0.05). Ultimately, ratio of PKM2 mRNA and PKM1 mRNA, despite being up-regulated by pcDNA3.1-XIST, was markedly lowered when miR-137 mimic was co-transfected (P< 0.05). LncRNA XIST/miR-137 axis reinforced glycolysis and chemo-tolerance of CRC by elevating PKM2/PKM1 ratio, providing an alternative to boost chemo-therapeutic efficacy of CRC patients.

Overexpression of long non-coding RNA urothelial carcinoma associated 1 causes paclitaxel (Taxol) resistance in colorectal cancer cells by promoting glycolysis

Some colorectal cancer patients show resistance to conventional chemotherapeutic agents including Taxol. This study investigated the roles of lncRNA urothelial carcinoma-associated 1 (UCA1) in the modulation of Taxol resistance in human colorectal cancer cells. According to our results, UCA1 was significantly upregulated in colon cancer cell lines/tissues. Construction of the UCA1 overexpression vector revealed that high UCA1 expression was responsible for Taxol resistance and that Taxol can induce UCA1 expression. Importantly, Taxol-resistant cells had a higher glycolysis rate and upregulated expression of the key glycolysis enzymes hexokinase 2 (HK2) and lactate dehydrogenase A (LDHA) than Taxol-sensitive cells. Further research demonstrated that UCA1 could directly regulate glycolysis by regulating HK2 and LDHA expression, which contributes to Taxol resistance. UCA1 is a potential target to overcome chemoresistance in colorectal cancer. We report the modulation of UCA-1-regulated glycolysis as a novel anticancer strategy along with the novel role of UCA1 in Taxol resistance.

The Mechanistic Roles of ncRNAs in Promoting and Supporting Chemoresistance of Colorectal Cancer.

Colorectal Cancer (CRC) is one of the most common gastrointestinal malignancies which has quite a high mortality rate. Despite the advances made in CRC treatment, effective therapy is still quite challenging, particularly due to resistance arising throughout the treatment regimen. Several studies have been carried out to identify CRC chemoresistance mechanisms, with research showing different signalling pathways, certain ATP binding cassette (ABC) transporters and epithelial mesenchymal transition (EMT), among others to be responsible for the failure of CRC chemotherapies. In the last decade, it has become increasingly evident that certain non-coding RNA (ncRNA) families are involved in chemoresistance. Research investigations have demonstrated that dysregulation of microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) contribute towards promoting resistance in CRC via different mechanisms. Considering the currently available data on this phenomenon, a better understanding of how these ncRNAs participate in chemoresistance can lead to suitable solutions to overcome this problem in CRC. This review will first focus on discussing the different mechanisms of CRC resistance identified so far. The focus will then shift onto the roles of miRNAs, lncRNAs and circRNAs in promoting 5-fluorouracil (5-FU), oxaliplatin (OXA), cisplatin and doxorubicin (DOX) resistance in CRC, specifically using ncRNAs which have been recently identified and validated under in vivo or in vitro conditions.

Inhibition of Heat-shock Protein 27 Reduces 5-Fluorouracil-acquired Resistance in Human Colon Cancer Cells.

In previous work we showed that expression of heat-shock protein 27 (HSP27; encoded by HSPB1) was associated with inherent resistance to 5-fluorouracil (5-FU). However, the relationship between HSP27 and acquired resistance remains unknown. We generated an acquired resistance model (WiDr-R) of a colon cancer cell line by exposing WiDr cells to 5-FU. Cell viability assays under treatment with 5-FU, as well as down-regulation of HSP27 using small interfering HSP27 RNA, were performed. HSP27 mRNA and protein expression was analyzed using real-time polymerase chain reaction and western blotting. 5-FU-acquired resistance induced overexpression of HSP27 mRNA and protein levels in WiDr-R cells. Furthermore, siRNA knockdown of HSP27 in WiDr-R cells reduced 5-FU-acquired resistance. These findings demonstrate that HSP27 is associated with 5-FU resistance in human colon cancer cell cells and suggest that HSP27 regulation represents a novel approach to overcoming chemoresistance in colorectal cancer.

TRIM Proteins in Colorectal Cancer: TRIM8 as a Promising Therapeutic Target in Chemo Resistance

Colorectal cancer (CRC) represents one of the most widespread forms of cancer in the population and, as all malignant tumors, often develops resistance to chemotherapies with consequent tumor growth and spreading leading to the patient’s premature death. For this reason, a great challenge is to identify new therapeutic targets, able to restore the drugs sensitivity of cancer cells. In this review, we discuss the role of TRIpartite Motifs (TRIM) proteins in cancers and in CRC chemoresistance, focusing on the tumor-suppressor role of TRIM8 protein in the reactivation of the CRC cells sensitivity to drugs currently used in the clinical practice. Since the restoration of TRIM8 protein levels in CRC cells recovers chemotherapy response, it may represent a new promising therapeutic target in the treatment of CRC.

ATAD3A stabilizes GRP78 to suppress ER stress for acquired chemoresistance in colorectal cancer.

AAA domain containing 3A (ATAD3A) is a nucleus-encoded mitochondrial protein with vital function in communication between endoplasmic reticulum (ER) and mitochondria which is participated in cancer metastasis. Here we show that elevated ATAD3A expression is clinically associated with poor 5-year disease-free survival in patients with colorectal cancer (CRC), especially high-risk CRC patients who received adjuvant chemotherapy. Our results indicated ATAD3A is significantly upregulated to reduce chemotherapy-induced cancer cell death. We found that knockdown of ATAD3A leads to dysregulation in protein processing for inducing ER stress by RNA sequencing (RNA-seq). In response to chemotherapy-induced ER stress, ATAD3A interacts with elevated GRP78 protein to assist protein folding and alleviate ER stress for cancer cell survival. This reduction of ER stress leads to reduce the surface exposure of calreticulin, which is the initiator of immunogenic cell death and antitumor immunity. However, silencing of ATAD3A enhances cell death, triggers the feasibility of chemotherapy-induced ER stress for antitumor immunity, increases infiltration of T lymphocytes and delays tumor regrowth in vitro and in vivo. Clinically, CRC patients with less ATAD3A have high density of CD45+ intratumoral infiltrating lymphocytes (TILs) and memory CD45RO+ TILs. Taken together, our results suggest that pharmacologic targeting to ATAD3A might be a potential therapeutic strategy to enhance antitumor immunity for CRC patients who received adjuvant chemotherapy.

Protein\u2013protein interaction analysis reveals a novel cancer stem cell related target TMEM17 in colorectal cancer

BackgroundCancer stem cells (CSCs) are a small subpopulation of cells within tumors with stem cell property. Increased evidence suggest that CSCs could be responsible for chemoresistance and recurrence in colorectal cancer (CRC). However, a reliable therapeutic target on CSCs is still lacking.MethodsHere we describe a two-step strategy to generate CSC targets with high selectivity for colon stem cell markers, specific proteins that are interacted with CSC markers were selected and subsequently validated in a survival analysis. TMEM17 protein was found and its biological functions in CRC cells were further examined. Finally, we utilized the Gene Set Enrichment Analysis (GSEA) to investigate the potential mechanisms of TMEM17 in CRC.ResultsBy combining protein–protein interaction (PPI) database and high-throughput gene profiles, network analysis revealed a cluster of colon CSCs related genes. In the cluster, TMEM17 was identified as a novel CSCs related gene. The results of in-vitro functional study demonstrated that TMEM17 depletion can suppress the proliferation of CRC cells and sensitize CRC cells to chemotherapy drugs. Enrichment analysis revealed that the expression of TMEM17 is associated with the magnitude of activation of the Wnt/β-catenin pathway. Further validation in clinical samples demonstrated that the TMEM17 expression was much higher in tumor than normal tissue and was associated with poor survival in CRC patients.ConclusionCollectively, our finding unveils the critical role of TMEM17 in CRC and TMEM17 could be a potential effective therapeutic target for tumor recurrence and chemoresistance in the colorectal cancer (CRC).

MicroRNA-9-5p increases the sensitivity of colorectal cancer cells to 5-fluorouracil by downregulating high mobility group A2 expression.

Chemotherapy drug 5-fluorouracil (5-FU) is the first-line treatment for colorectal cancer (CRC); however, 5-FU resistance decreases CRC therapeutic efficiency. A previous study revealed that microRNA (miR)-9-5p serves an antitumor effect in CRC. However, the effect of miR-9-5p in CRC chemoresistance remains unknown. In the present study, two CRC cell lines, including HT-29 and HCT-116 cells, were used to investigate the impact of miR-9-5p in overcoming 5-FU resistance. The results revealed that treatment with 5-FU decreased CRC cell viability and upregulated miR-9-5p expression in both CRC cells. Knockdown of miR-9-5p decreased HCT-116 cell sensitivity to 5-FU and inhibited apoptosis. By contrast, miR-9-5p overexpression enhanced the sensitivity of HT-29 cells to 5-FU and induced apoptosis. Additionally, it was confirmed that miR-9-5p directly targeted high mobility group A2 (HMGA2). HMGA2 overexpression reversed miR-9-5p-induced HT-29 apoptosis. The present study indicated that miR-9-5p enhanced the sensitivity of CRC cells to 5-FU via downregulating HMGA2 expression.