Large tumor suppressor kinase 2 overexpression attenuates 5-FU-resistance in colorectal cancer via activating the JNK-MIEF1-mitochondrial division pathway

Nanoplastics induced health risk: Insights into intestinal barrier homeostasis and potential remediation strategy by dietary intervention

Aged nanoplastics (aged-NPs) have unique characteristics endowed by environmental actions, such as rough surface, high oxygen content. Although studies have highlighted the potential hazards of aged-NPs, limited research has provided strategies for aged-NPs pollution remediation. The dietary intervention of quercetin is a novel insight to address the health risks of aged-NPs. This study explored the impact of aged-NPs on intestinal barrier homeostasis at the environmentally relevant dose and investigated the alleviating effects of quercetin on aged-NPs toxicity through transcriptomics and molecular biology analysis. It indicated that aged-NPs induced intestinal barrier dysfunction, which was characterized by higher permeability, increased inflammation, and loss of epithelial integrity, while quercetin restored it. Aged-NPs disrupted redox homeostasis, upregulated inflammatory genes controlled by AP-1, and led to Bax-dependent mitochondrial apoptosis. Quercetin intervention effectively mitigated inflammation and apoptosis by activating the Nrf2. Thus, quercetin decreased intestinal free radical levels, inhibiting the phosphorylation of p38 and JNK. This study unveiled the harmful effects of aged-NPs on intestinal homeostasis and the practicability of dietary intervention against aged-NPs toxicity. These findings broaden the understanding of the NPs toxicity and provide an effective dietary strategy to relieve the health risks of NPs. ENVIRONMENTAL IMPLICATIONS: Growing levels of NPs pollution have represented severe health hazards to the population. This study focuses on the toxic mechanism of aged-NPs on the intestinal barrier and the alleviating effect of quercetin dietary intervention, which considers the environmental action and relevant dose. It revealed the harmful effects of aged-NPs on intestinal inflammation with the key point of free radical generation. Furthermore, a quercetin-rich diet holds significant promise for addressing and reversing intestinal damage caused by aged-NPs by maintaining intracellular redox homeostasis. These findings provide an effective dietary strategy to remediate human health risks caused by NPs.

Mitochondrial dynamics and colorectal cancer biology: mechanisms and potential targets

Colorectal cancer (CRC) is a significant public health concern, and its development is associated with mitochondrial dysfunction. Mitochondria can adapt to the high metabolic demands of cancer cells owing to their plasticity and dynamic nature. The fusion-fission dynamics of mitochondria play a crucial role in signal transduction and metabolic functions of CRC cells. Enhanced mitochondrial fission promotes the metabolic reprogramming of CRC cells, leading to cell proliferation, metastasis, and chemoresistance. Excessive fission can also trigger mitochondria-mediated apoptosis. In contrast, excessive mitochondrial fusion leads to adenosine triphosphate (ATP) overproduction and abnormal tumor proliferation, whereas moderate fusion protects intestinal epithelial cells from oxidative stress-induced mitochondrial damage, thus preventing colitis-associated cancer (CAC). Therefore, an imbalance in mitochondrial dynamics can either promote or inhibit CRC progression. This review provides an overview of the mechanism underlying mitochondrial fusion-fission dynamics and their impact on CRC biology. This revealed the dual role of mitochondrial fusion-fission dynamics in CRC development and identified potential drug targets. Additionally, this study partially explored mitochondrial dynamics in immune and vascular endothelial cells in the tumor microenvironment, suggesting promising prospects for targeting key fusion/fission effector proteins against CRC.

Mitochondrial metabolism: a predictive biomarker of radiotherapy efficacy and toxicity

INTRODUCTION

Radiotherapy is a mainstay of cancer treatment. Clinical studies revealed a heterogenous response to radiotherapy, from a complete response to even disease progression. To that end, finding the relative prognostic factors of disease outcomes and predictive factors of treatment efficacy and toxicity is essential. It has been demonstrated that radiation response depends on DNA damage response, cell cycle phase, oxygen concentration, and growth rate. Emerging evidence suggests that altered mitochondrial metabolism is associated with radioresistance.

METHODS

This article provides a comprehensive evaluation of the role of mitochondria in radiotherapy efficacy and toxicity. In addition, it demonstrates how mitochondria might be involved in the famous 6Rs of radiobiology.

RESULTS

In terms of this idea, decreasing the mitochondrial metabolism of cancer cells may increase radiation response, and enhancing the mitochondrial metabolism of normal cells may reduce radiation toxicity. Enhancing the normal cells (including immune cells) mitochondrial metabolism can potentially improve the tumor response by enhancing immune reactivation. Future studies are invited to examine the impacts of mitochondrial metabolism on radiation efficacy and toxicity. Improving radiotherapy response with diminishing cancer cells' mitochondrial metabolism, and reducing radiotherapy toxicity with enhancing normal cells' mitochondrial metabolism.

Thiol oxidative stress-dependent degradation of transglutaminase2 via protein S-glutathionylation sensitizes 5-fluorouracil therapy in 5-fluorouracil-resistant colorectal cancer cells

5-Fluorouracil (5-Fu) is a first-line drug for colorectal cancer (CRC) therapy. However, the development of 5-Fu resistance limits its chemotherapeutic effectiveness and often leads to poor prognoses of CRC. Transglutaminase 2 (TGM2), a member of the transglutaminase family, is considered to be associated with chemoresistance through apoptotic prevention in various cancers including CRC. TGM2 was found to be overexpressed in two 5-Fu-resistant CRC cell lines and down-regulated by increased thiol oxidative stress induced by inhibition of glutathione reductase (GR). The present study aimed to explore the role of TGM2 in 5-Fu-resistant CRC and the mechanism of action by which the elevated thiol oxidative stress down-regulates TGM2 protein level. The results revealed that 5-Fu-resistance induced by overexpression of TGM2 in CRC cells was reversed through up-regulation of thiol oxidative stress. Knockdown of TGM2 increased the chemosensitivity of CRC cells to 5-Fu. Thiol oxidative stress potentially enhanced the therapeutic effect of 5-Fu in the resistant CRC cells by promotion of 5-Fu-induced apoptosis through down-regulation of TGM2. The elevated thiol oxidative stress increased the S-glutathionylation of TGM2 and led to proteasomal degradation of TGM2. Furthermore, Cys193 was identified as the S-glutathionylation site in TGM2, and its mutation resulted in thiol oxidative stress-mediated CRC cell apoptotic resistance. TGM2-induced EMT was also suppressed by the elevated thiol oxidative stress. A xenograft tumor model confirmed the effect of thiol oxidative stress in the reversal of 5-Fu resistance in CRC cells in vivo. TGM2 protein expression level was found to be significantly higher in human CRC specimens than in non-cancerous colorectal tissues. Taken together, the present data suggest an important role of TGM2 in 5-Fu resistance in CRC cells. Up-regulation of thiol oxidative stress could be a potential therapeutic approach for treating 5-Fu-resistant CRC and TGM2 may serve as a potential therapeutic target of thiol oxidative stress.

The Hippo signalling pathway and its implications in human health and diseases

As an evolutionarily conserved signalling network, the Hippo pathway plays a crucial role in the regulation of numerous biological processes. Thus, substantial efforts have been made to understand the upstream signals that influence the activity of the Hippo pathway, as well as its physiological functions, such as cell proliferation and differentiation, organ growth, embryogenesis, and tissue regeneration/wound healing. However, dysregulation of the Hippo pathway can cause a variety of diseases, including cancer, eye diseases, cardiac diseases, pulmonary diseases, renal diseases, hepatic diseases, and immune dysfunction. Therefore, therapeutic strategies that target dysregulated Hippo components might be promising approaches for the treatment of a wide spectrum of diseases. Here, we review the key components and upstream signals of the Hippo pathway, as well as the critical physiological functions controlled by the Hippo pathway. Additionally, diseases associated with alterations in the Hippo pathway and potential therapies targeting Hippo components will be discussed.

LINC01088 regulates the miR-95/LATS2 pathway through the ceRNA mechanism to inhibit the growth, invasion and migration of gastric cancer cells

Background: In gastric cancer, a malignant condition with a dismal prognosis, long non-coding RNAs (LncRNAs) play a significant regulatory role. They often compete with microRNAs through the ceRNA mechanism to affect the expression of target mRNA. However, the specific clinical value and mechanism of action of LncRNA in gastric cancer are still unclear. Methods: This study detected the expression and clinical value of LINC01088 in gastric cancer tissues. Furthermore, the biological functions of LINC01088 and the regulation mechanism of the miR-95/LATS2 pathway were explored.Results: LINC01088 and LATS2 mRNA expression decreased, and miR-95 increased in gastric cancer tissues. LINC01088 has an excellent positive correlation with LATS2 mRNA, which may be a ceRNA pair; LINC01088 has binding sites with miR-95. Gene interference tests on gastric cancer cell lines revealed that LINC01088 could prevent gastric cancer cells from proliferating, invading, and migrating. The function of LINC01088 is achieved by regulating the miR-95/LATS2 pathway through the ceRNA mechanism.Conclusion: The results of this study show that LINC01088 expression is significantly reduced in gastric cancer tissues and cell lines. LINC01088 inhibits gastric cancer cells’ proliferation, invasion, and migration by regulating the miR-95/LATS2 pathway via the ceRNA mechanism.

Recent Updates on Mechanisms of Resistance to 5-Fluorouracil and Reversal Strategies in Colon Cancer Treatment

5-Fluorouracil (5-FU) plus leucovorin (LV) remain as the mainstay standard adjuvant chemotherapy treatment for early stage colon cancer, and the preferred first-line option for metastatic colon cancer patients in combination with oxaliplatin in FOLFOX, or irinotecan in FOLFIRI regimens. Despite treatment success to a certain extent, the incidence of chemotherapy failure attributed to chemotherapy resistance is still reported in many patients. This resistance, which can be defined by tumor tolerance against chemotherapy, either intrinsic or acquired, is primarily driven by the dysregulation of various components in distinct pathways. In recent years, it has been established that the incidence of 5-FU resistance, akin to multidrug resistance, can be attributed to the alterations in drug transport, evasion of apoptosis, changes in the cell cycle and DNA-damage repair machinery, regulation of autophagy, epithelial-to-mesenchymal transition, cancer stem cell involvement, tumor microenvironment interactions, miRNA dysregulations, epigenetic alterations, as well as redox imbalances. Certain resistance mechanisms that are 5-FU-specific have also been ascertained to include the upregulation of thymidylate synthase, dihydropyrimidine dehydrogenase, methylenetetrahydrofolate reductase, and the downregulation of thymidine phosphorylase. Indeed, the successful modulation of these mechanisms have been the game plan of numerous studies that had employed small molecule inhibitors, plant-based small molecules, and non-coding RNA regulators to effectively reverse 5-FU resistance in colon cancer cells. It is hoped that these studies would provide fundamental knowledge to further our understanding prior developing novel drugs in the near future that would synergistically work with 5-FU to potentiate its antitumor effects and improve the patient's overall survival.

The Hippo Signaling Pathway in Drug Resistance in Cancer

Simple Summary

Although great breakthroughs have been made in cancer treatment following the development of targeted therapy and immune therapy, resistance against anti-cancer drugs remains one of the most challenging conundrums. Considerable effort has been made to discover the underlying mechanisms through which malignant tumor cells acquire or develop resistance to anti-cancer treatment. The Hippo signaling pathway appears to play an important role in this process. This review focuses on how components in the human Hippo signaling pathway contribute to drug resistance in a variety of cancer types. This article also summarizes current pharmacological interventions that are able to target the Hippo signaling pathway and serve as potential anti-cancer therapeutics.

Abstract

Chemotherapy represents one of the most efficacious strategies to treat cancer patients, bringing advantageous changes at least temporarily even to those patients with incurable malignancies. However, most patients respond poorly after a certain number of cycles of treatment due to the development of drug resistance. Resistance to drugs administrated to cancer patients greatly limits the benefits that patients can achieve and continues to be a severe clinical difficulty. Among the mechanisms which have been uncovered to mediate anti-cancer drug resistance, the Hippo signaling pathway is gaining increasing attention due to the remarkable oncogenic activities of its components (for example, YAP and TAZ) and their druggable properties. This review will highlight current understanding of how the Hippo signaling pathway regulates anti-cancer drug resistance in tumor cells, and currently available pharmacological interventions targeting the Hippo pathway to eradicate malignant cells and potentially treat cancer patients.

Repressing PDCD4 activates JNK/ABCG2 pathway to induce chemoresistance to fluorouracil in colorectal cancer cells

Background

Colorectal cancer (CRC) is the third major cause of cancer-related death worldwide, and fluorouracil (5-FU) is widely used in the treatment of CRC. However, acquired resistance to 5-FU has become an obstacle in the effective treatment of CRC. Adenosine triphosphate (ATP)-binding cassette sub-family G member 2 (ABCG2) has been found highly expressed in CRC patients with poor responsiveness to folinic acid/5-FU/irinotecan. However, the mechanisms of 5-FU resistance regulated by ABCG2 in CRC cells remain to be comprehensively understood. We aimed to explore the upstream mechanisms of ABCG2 involved in the regulation of chemoresistance in CRC cells.

Methods

We investigated the potential mechanisms of 5-FU resistance in HCT116, RKO, RKO microRNA-21 (miR-21) knockout, and acquired 5-FU-resistant HCT116 (HCT116/FUR) cells. The biochemical and biological analyses were conducted using semiquantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting, transfections, and rescue experiments, along with cell proliferation, viability, and colony formation assays. In order to investigate the efficacy of inhibiting the c-Jun NH2 terminal kinase (JNK) pathway to overcome 5-FU resistance, HCT116 and 5-FU-resistant HCT116 cells were inoculated into BALB/c-nu/nu mice to establish the cell-derived xenograft model.

Results

The results showed that ABCG2 expression in HCT116/FUR cells was higher compared to HCT116 cells. Overexpression of ABCG2 decreased sensitivity to 5-FU in HCT116 cells, but knockdown of ABCG2 decreased the survival rate in HCT116/FUR cells. Additionally, repressing programmed cell death 4 (PDCD4) activated the JNK pathway in HCT116/FUR cells. Overexpression of PDCD4 inhibited phosphorylation of c-Jun and ABCG2 expression, and recovered sensitivity to 5-FU in HCT116/FUR cells. Moreover, treatment with the JNK pathway inhibitor SP600125 downregulated ABCG2 expression and rescued sensitivity to 5-FU in HCT116/FUR cells. We also found that miR-21 expression in HCT116/FUR cells was higher compared to HCT116 cells. Finally, 5-FU treatment in combination with SP600125 significantly decreased tumorigenicity compared to other treatments in vivo.

Conclusions

Our results demonstrated that 5-FU treatment upregulated miR-21, which directly repressed PDCD4, and subsequently activated the JNK pathway, leading to the upregulation of ABCG2 in CRC cells. Inhibition of the JNK pathway overcame acquired 5-FU resistance both in vivo and in vitro.

5-Fluorouracil resistance mechanisms in colorectal cancer: From classical pathways to promising processes

Colorectal cancer (CRC) is a public health problem. It is the third most common cancer in the world, with nearly 1.8 million new cases diagnosed in 2018. The only curative treatment is surgery, especially for early tumor stages. When there is locoregional or distant invasion, chemotherapy can be introduced, in particular 5-fluorouracil (5-FU). However, the disease can become tolerant to these pharmaceutical treatments: resistance emerges, leading to early tumor recurrence. Different mechanisms can explain this 5-FU resistance. Some are disease-specific, whereas others, such as drug efflux, are evolutionarily conserved. These mechanisms are numerous and complex and can occur simultaneously in cells exposed to 5-FU. In this review, we construct a global outline of different mechanisms from disruption of 5-FU-metabolic enzymes and classic cellular processes (apoptosis, autophagy, glucose metabolism, oxidative stress, respiration, and cell cycle perturbation) to drug transporters and epithelial-mesenchymal transition induction. Particular interest is directed to tumor microenvironment function as well as epigenetic alterations and miRNA dysregulation, which are the more promising processes that will be the subject of much research in the future.

Hypoxia-Induced Placenta-Specific microRNA (miR-512-3p) Promotes Hepatocellular Carcinoma Progression by Targeting Large Tumor Suppressor Kinase 2

Background

Sustained proliferation and active metastasis are hallmarks of cancer, and they pose major challenges to the development of treatments and a cure for hepatocellular carcinoma (HCC). Thus, the mechanisms of proliferation, migration, and invasion of cancer cells need to be investigated. Many studies indicate that dysregulation of microRNA plays important roles in the progression of HCC, but the role of placenta-specific microRNA (miR-512-3p) in HCC has not been systematically investigated.

Purpose

In the current study, the expression, biological function, and mechanisms of miR-512-3p involvement in HCC were investigated.

Methods

Real-time quantitative polymerase chain reaction assays were conducted to determine miR-512-3p levels in HCC tissues and cell lines. The StarBase V3.0 online platform was used to compare miR-512-3p levels in HCC tissues with TCGA data and to identify potential miR-512-3p target genes. Associations between miR-512-3p and clinicopathological characteristics were analyzed statistically. MTT, ethynyl deoxyuridine, and transwell assays were performed to assess cell viability, proliferation, migration, and invasion. The luciferase reporter gene assay was used to verify target genes. Recuse assays were performed to confirm whether large tumor suppressor kinase 2 (LATS2) participated in the regulatory effects of miR-512-3p on HCC cell proliferation and motility, and whether miR-512-3p mediated the tumor-promoting effects of hypoxia.

Results

miR-512-3p was upregulated in HCC and it was associated with worse survival and unfavorable clinicopathological characteristics. Functional assays indicated that miR-512-3p contributed to HCC cell proliferation, migration, and invasion. Mechanistically, LATS2—a downstream target of miR-512-3p—mediated the tumor-promoting effects of miR-512-3p in HCC. Hypoxia could elevate miR-512-3p levels in HCC cells, and miR-512-3p partially mediated the tumor-promoting effects of hypoxia.

Conclusion

Hypoxia-induced miR-512-3p contributes to HCC cell proliferation, migration, and invasion by targeting LATS2 and inhibiting the Hippo/yes-associated protein 1 pathways.

ROCK1 knockdown inhibits non-small-cell lung cancer progression by activating the LATS2-JNK signaling pathway

Rho-associated kinase 1 (ROCK1) regulates tumor metastasis by maintaining cellular cytoskeleton homeostasis. However, the precise role of ROCK1 in non-small-cell lung cancer (NSCLC) apoptosis remains largely unknown. In this study, we examined the function of ROCK1 in NSCLS survival using RNA interference-mediated knockdown. Our results showed that ROCK1 knockdown reduced A549 lung cancer cell viability in vitro. It also inhibited A549 cell migration and proliferation. Transfection of ROCK1 siRNA was associated with increased expression of large tumor suppressor kinase 2 (LATS2) and c-Jun N-terminal kinase (JNK). Moreover, ROCK1 knockdown-induced A549 cell apoptosis and inhibition of proliferation were suppressed by LATS2 knockdown or JNK inactivation, suggesting that ROCK1 deficiency triggers NSCLC apoptosis in a LATS2-JNK pathway-dependent manner. Functional analysis further demonstrated that ROCK1 knockdown dysregulated mitochondrial dynamics and inhibited mitochondrial biogenesis. This effect too was reversed by LATS2 knockdown or JNK inactivation. We have thus identified a potential pathway by which ROCK1 downregulation triggers apoptosis in NSCLC by inducing LATS2-JNK-dependent mitochondrial damage.

The Role of a Key Amino Acid Position in Species-Specific Proteinaceous dUTPase Inhibition

Protein inhibitors of key DNA repair enzymes play an important role in deciphering physiological pathways responsible for genome integrity, and may also be exploited in biomedical research. The staphylococcal repressor StlSaPIbov1 protein was described to be an efficient inhibitor of dUTPase homologues showing a certain degree of species-specificity. In order to provide insight into the inhibition mechanism, in the present study we investigated the interaction of StlSaPIbov1 and Escherichia coli dUTPase. Although we observed a strong interaction of these proteins, unexpectedly the E. coli dUTPase was not inhibited. Seeking a structural explanation for this phenomenon, we identified a key amino acid position where specific mutations sensitized E. coli dUTPase to StlSaPIbov1 inhibition. We solved the three-dimensional (3D) crystal structure of such a mutant in complex with the substrate analogue dUPNPP and surprisingly found that the C-terminal arm of the enzyme, containing the P-loop-like motif was ordered in the structure. This segment was never localized before in any other E. coli dUTPase crystal structures. The 3D structure in agreement with solution phase experiments suggested that ordering of the flexible C-terminal segment upon substrate binding is a major factor in defining the sensitivity of E. coli dUTPase for StlSaPIbov1 inhibition.