Coexisting Molecular Determinants of Acquired Oxaliplatin Resistance in Human Colorectal and Ovarian Cancer Cell Lines

Discovery of the Next-Generation Platinum-Based Anticancer Agents for Combating Oxaliplatin-Induced Drug Resistance

Oxaliplatin-based chemotherapy has proven to be one of the most effective treatments for advanced or metastatic colorectal cancer. However, increasing clinical resistance to oxaliplatin poses unprecedented challenges for both patients and clinicians. Despite extensive efforts to combat this issue, to date, no new molecules have been discovered that can successfully replace oxaliplatin. With the aim of developing a new generation of Pt(II)-based anticancer agents in response to the challenges of oxaliplatin-induced drug resistance, we performed a systematic screening of new Pt(II)-complexes with a quantitative structure-activity relationship (QSAR) study based on their antiresistance activity against oxaliplatin-resistant colon cancer cells. The results revealed that both the structure and chirality of the chelating ligand had a significant impact on the antiresistance properties of the Pt(II)-complexes. Our study culminated in the identification of chiral R-binaphthyldiamine-ligated Pt(II)-malonatoglycoconjugates that can completely counteract oxaliplatin resistance with excellent in vitro and in vivo potency.

The synergistic effect of oxaliplatin and punicalagin on colon cancer cells Caco-2 death

Objectives

The objectives of the study are to investigate the synergistic effect of oxaliplatin (oxa) and punicalagin (pun) on the death of colon cancer cells (Caco-2) by apoptosis and autophagy.

Methods

The effects of the combined treatments (5 μM oxa + 50 μM pun, 5 μM oxa + 75 μM pun, 20 μM oxa + 50 μM pun, and 5 μM oxa + 75 μM pun) were compared with untreated Caco2 cells (control) or cells treated with oxa alone. Apoptosis was detected using an Annex in V FITC flow cytometry assay and poly (ADP-ribose) polymerase cleavage by western blotting. Light chain 3 was detected by western blotting as an autophagy marker.

Results

The combined treatments significantly increased the number of apoptotic cells in comparison to untreated cells or cells treated with oxa alone. By contrast, the combined treatments had no significant effect on autophagy.

Conclusion

The combined treatment significantly promoted cell death through apoptosis while maintaining a basal level of autophagy.

2022 Peritoneal Surface Oncology Group International Consensus on HIPEC Regimens for Peritoneal Malignancies: Colorectal Cancer

BACKGROUND

Selected patients with peritoneal metastases of colorectal cancer (PM-CRC) can benefit from potentially curative cytoreductive surgery (CRS) ± hyperthermic intraperitoneal chemotherapy (HIPEC), with a median overall survival (OS) of more than 40 months.

OBJECTIVE

The aims of this evidence-based consensus were to define the indications for HIPEC, to select the preferred HIPEC regimens, and to define research priorities regarding the use of HIPEC for PM-CRC.

METHODS

The consensus steering committee elaborated and formulated pertinent clinical questions according to the PICO (patient, intervention, comparator, outcome) method and assessed the evidence according to the Grading of Recommendation, Assessment, Development, and Evaluation (GRADE) framework. Standardized evidence tables were presented to an international expert panel to reach a consensus (4-point, weak and strong positive/negative) on HIPEC regimens and research priorities through a two-round Delphi process. The consensus was defined as ≥ 50% agreement for the 4-point consensus grading or ≥ 70% for either of the two combinations.

RESULTS

Evidence was weak or very weak for 9/10 clinical questions. In total, 70/90 eligible panelists replied to both Delphi rounds (78%), with a consensus for 10/10 questions on HIPEC regimens. There was strong negative consensus concerning the short duration, high-dose oxaliplatin (OX) protocol (55.7%), and a weak positive vote (53.8-64.3%) in favor of mitomycin-C (MMC)-based HIPEC (preferred choice: Dutch protocol: 35 mg/m2, 90 min, three fractions), both for primary cytoreduction and recurrence. Determining the role of HIPEC after CRS was considered the most important research question, regarded as essential by 85.7% of the panelists. Furthermore, over 90% of experts suggest performing HIPEC after primary and secondary CRS for recurrence > 1 year after the index surgery.

CONCLUSIONS

Based on the available evidence, despite the negative results of PRODIGE 7, HIPEC could be conditionally recommended to patients with PM-CRC after CRS. While more preclinical and clinical data are eagerly awaited to harmonize the procedure further, the MMC-based Dutch protocol remains the preferred regimen after primary and secondary CRS.

The Role of Cyanidin-3-O-glucoside in Modulating Oxaliplatin Resistance by Reversing Mesenchymal Phenotype in Colorectal Cancer

BACKGROUND

Epithelial-mesenchymal transition (EMT) plays an important role in the biological and biochemical processes of cells, and it is a critical process in the malignant transformation, and mobility of cancer. Additionally, EMT is one of the main mechanisms contributing to chemoresistance. Resistance to oxaliplatin (OXA) poses a momentous challenge in the chemotherapy of advanced colorectal cancer (CRC) patients, highlighting the need to reverse drug resistance and improve patient survival. In this study, we explored the response of cyanidin-3-O-glucoside (C3G), the most abundant anthocyanin in plants, on the mechanisms of drug resistance in cancer, with the purpose of overcoming acquired OXA resistance in CRC cell lines.

METHODS

We generated an acquired OXA-resistant cell line, named HCT-116-ROx, by gradually exposing parental HCT-116 cells to increasing concentrations of OXA. To characterize the resistance, we performed cytotoxicity assays and shape factor analyses. The apoptotic rate of both resistant and parental cells was determined using Hoechst 33342/Propidium Iodide (PI) fluorescence staining. Migration capacity was evaluated using a wound-healing assay. The mesenchymal phenotype was assessed through qRT-PCR and immunofluorescence staining, employing E-cadherin, N-cadherin, and Vimentin markers.

RESULTS

Resistance characterization announced decreased OXA sensitivity in resistant cells compared to parental cells. Moreover, the resistant cells exhibited a spindle cell morphology, indicative of the mesenchymal phenotype. Combined treatment of C3G and OXA resulted in an augmented apoptotic rate in the resistant cells. The migration capacity of resistant cells was higher than parental cells, while treatment with C3G decreased the migration rate of HCT-116-ROx cells. Analysis of EMT markers showed that HCT-116-ROx cells exhibited loss of the epithelial phenotype (E-cadherin) and gain of the mesenchymal phenotype (N-cadherin and Vimentin) compared to HCT-116 cells. However, treatment of resistant cells with C3G reversed the mesenchymal phenotype.

CONCLUSION

The morphological observations of cells acquiring oxaliplatin resistance indicated the loss of the epithelial phenotype and the acquisition of the mesenchymal phenotype. These findings suggest that EMT may contribute to acquired OXA resistance in CRC. Furthermore, C3G decreased the mobility of resistant cells, and reversed the EMT process, indicating its potential to overcome acquired OXA resistance.

Chidamide and Oxaliplatin Synergistically Inhibit Colorectal Cancer Growth by Regulating the RPS27A-MDM2-P53 Axis

Purpose

The present study explored the anti-tumor effects of chidamide plus oxaliplatin on colorectal cancer (CRC) and examined its underlying mechanism.

Material and Methods

First, the Combination Index (CI) of chidamide and oxaliplatin was evaluated via CCK-8 assay. Second, the effects of chidamide and oxaliplatin monotherapy and the combined treatment on cell proliferation, invasion, migration, and apoptosis were detected. Third, whole-transcriptome RNA sequencing (RNA-seq) was performed to seek the potential targeted gene by which chidamide plus oxaliplatin exerted anti-tumor effects. Fourth, the validation of the targeted gene and the signal pathway it regulated were performed. Finally, the anti-tumor effect of chidamide plus oxaliplatin on mice xenograft was examined.

Results

Chidamide and oxaliplatin acted synergistically to inhibit CRC growth in vitro and in vivo (CI<1). Besides, compared with oxaliplatin monotherapy, chidamide could significantly enhance oxaliplatin-induced inhibition in cell proliferation, invasion, and migration, and promotion in HCT-116 and RKO cell apoptosis (P<0.05). The RNA-seq displayed that, compared to oxaliplatin monotherapy, RPS27A mRNA was evidently decreased in HCT-116 cells treated with chidamide plus oxaliplatin (P<0.001). Then, we found RPS27A was highly expressed in CRC tissues and CRC cell lines (P<0.001). Silence of RPS27A attenuated proliferation and induced apoptosis in HCT-116 and RKO cells via downregulation of MDM2 expression and upregulation of P53. Next, RPS27A overexpression could partially reverse chidamide plus oxaliplatin induced growth inhibition and apoptosis in HCT-116 and RKO cells (P<0.01). RPS27A overexpression could promote the upregulation of MDM2 and downregulation of P53 after the combined treatment of chidamide with oxaliplatin.

Conclusion

Chidamide and oxaliplatin acted synergistically to suppress CRC growth by the inhibition of the RPS27A-MDM2-p53 axis.

β-Lapachone Exerts Anticancer Effects by Downregulating p53, Lys-Acetylated Proteins, TrkA, p38 MAPK, SOD1, Caspase-2, CD44 and NPM in Oxaliplatin-Resistant HCT116 Colorectal Cancer Cells

β-lapachone (β-Lap), a topoisomerase inhibitor, is a naturally occurring ortho-naphthoquinone phytochemical and is involved in drug resistance mechanisms. Oxaliplatin (OxPt) is a commonly used chemotherapeutic drug for metastatic colorectal cancer, and OxPt-induced drug resistance remains to be solved to increase chances of successful therapy. To reveal the novel role of β-Lap associated with OxPt resistance, 5 μM OxPt-resistant HCT116 cells (HCT116-OxPt-R) were generated and characterized via hematoxylin staining, a CCK-8 assay and Western blot analysis. HCT116-OxPt-R cells were shown to have OxPt-specific resistance, increased aggresomes, upregulated p53 and downregulated caspase-9 and XIAP. Through signaling explorer antibody array, nucleophosmin (NPM), CD37, Nkx-2.5, SOD1, H2B, calreticulin, p38 MAPK, caspase-2, cadherin-9, MMP23B, ACOT2, Lys-acetylated proteins, COL3A1, TrkA, MPS-1, CD44, ITGA5, claudin-3, parkin and ACTG2 were identified as OxPt-R-related proteins due to a more than two-fold alteration in protein status. Gene ontology analysis suggested that TrkA, Nkx-2.5 and SOD1 were related to certain aggresomes produced in HCT116-OxPt-R cells. Moreover, β-Lap exerted more cytotoxicity and morphological changes in HCT116-OxPt-R cells than in HCT116 cells through the downregulation of p53, Lys-acetylated proteins, TrkA, p38 MAPK, SOD1, caspase-2, CD44 and NPM. Our results indicate that β-Lap could be used as an alternative drug to overcome the upregulated p53-containing OxPt-R caused by various OxPt-containing chemotherapies.

Revisiting the Anti-Cancer Toxicity of Clinically Approved Platinating Derivatives

Cisplatin (CDDP), carboplatin (CP), and oxaliplatin (OXP) are three platinating agents clinically approved worldwide for use against a variety of cancers. They are canonically known as DNA damage inducers; however, that is only one of their mechanisms of cytotoxicity. CDDP mediates its effects through DNA damage-induced transcription inhibition and apoptotic signalling. In addition, CDDP targets the endoplasmic reticulum (ER) to induce ER stress, the mitochondria via mitochondrial DNA damage leading to ROS production, and the plasma membrane and cytoskeletal components. CP acts in a similar fashion to CDDP by inducing DNA damage, mitochondrial damage, and ER stress. Additionally, CP is also able to upregulate micro-RNA activity, enhancing intrinsic apoptosis. OXP, on the other hand, at first induces damage to all the same targets as CDDP and CP, yet it is also capable of inducing immunogenic cell death via ER stress and can decrease ribosome biogenesis through its nucleolar effects. In this comprehensive review, we provide detailed mechanisms of action for the three platinating agents, going beyond their nuclear effects to include their cytoplasmic impact within cancer cells. In addition, we cover their current clinical use and limitations, including side effects and mechanisms of resistance.

Assessment of spatial transcriptomics for oncology discovery

Tumor heterogeneity is a major challenge for oncology drug discovery and development. Understanding of the spatial tumor landscape is key to identifying new targets and impactful model systems. Here, we test the utility of spatial transcriptomics (ST) for oncology discovery by profiling 40 tissue sections and 80,024 capture spots across a diverse set of tissue types, sample formats, and RNA capture chemistries. We verify the accuracy and fidelity of ST by leveraging matched pathology analysis, which provides a ground truth for tissue section composition. We then use spatial data to demonstrate the capture of key tumor depth features, identifying hypoxia, necrosis, vasculature, and extracellular matrix variation. We also leverage spatial context to identify relative cell-type locations showing the anti-correlation of tumor and immune cells in syngeneic cancer models. Lastly, we demonstrate target identification approaches in clinical pancreatic adenocarcinoma samples, highlighting tumor intrinsic biomarkers and paracrine signaling.

Role of AMPK in Regulation of Oxaliplatin-Resistant Human Colorectal Cancer

Oxaliplatin is a platinum analog that can interfere with DNA replication and transcription. Continuous exposure to oxaliplatin results in chemoresistance; however, this mechanism is not well known. In this study, oxaliplatin-resistant (OR) colorectal cancer (CRC) cells of HCT116, HT29, SW480 and SW620 were established by gradually increasing the drug concentration to 2.5 μM. The inhibitory concentrations of cell growth by 50% (IC50) of oxaliplatin were 4.40-12.7-fold significantly higher in OR CRC cells as compared to their respective parental (PT) CRC cells. Phospho-Akt and phospho-mammalian target of rapamycin (mTOR) decreased in PT CRC cells but was overexpressed in OR CRC cells in response to oxaliplatin. In addition, an oxaliplatin-mediated decrease in phospho-AMP-activated protein kinase (AMPK) in PT CRC cells induced autophagy. Contrastingly, an increased phospho-AMPK in OR CRC cells was accompanied by a decrease in LC3B, further inducing the activity of glycolytic enzymes, such as glucose transporter 1 (GLUT1), 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase 3 (PFKFB3) and phosphofructokinase 1 (PFK1), to mediate cell survival. Inhibition of AMPK in OR CRC cells induced autophagy through inactivation of Akt/mTOR pathway and a decrease in GLUT1, PFKFB3, and PFK1. Collectively, targeting AMPK may provide solutions to overcome chemoresistance in OR CRC cells and restore chemosensitivity to anticancer drugs.

Tanshinone IIA reverses oxaliplatin resistance in colorectal cancer through microRNA-30b-5p/AVEN axis

This research aims to explore the role of Tanshinone IIA (Tan IIA) and microRNA (miR)-30b-5p in chemoresistance of colorectal cancer (CRC). The expression levels of miR-30b-5p and apoptosis and caspase activation inhibitor (AVEN) was detected by reverse transcription-quantitative polymerase chain reaction assay. The cell proliferation and apoptosis were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry assays. The target relationship between miR-30b-5p and AVEN was confirmed by Dual-luciferase reporter assay. Transwell assay was performed to assess CRC cells’ metastasis. Western blot was carried out to measure the apoptosis-related protein. The results showed that miR-30b-5p was lowly expressed in oxaliplatin-resistance CRC cells SW480 (SW480/R) compared to SW480 cells. Overexpression of miR-30b-5p significantly suppressed the malignant biological behaviors of SW480/R cells and significantly promoted the sensitivity of SW480/R cells to oxaliplatin by down-regulated AVEN expression. Besides, Tan IIA treatment upregulated miR-30b-5p expression in SW480/R cells. Moreover, miR-30b-5p upregulation strengthened the promoting effect of Tan IIA on the sensitivity of SW480/R cells to oxaliplatin. In conclusion, Tan IIA and miR-30b-5p could reverse oxaliplatin resistance of CRC cells and may thus be potential treatment strategies for treating patients with CRC.

Glutathione S-Transferase Alpha 4 Promotes Proliferation and Chemoresistance in Colorectal Cancer Cells

Glutathione S-transferase alpha 4 (GSTA4) is a phase II detoxifying enzyme that is overexpressed in colorectal cancer (CRC) and regulated by the oncogenic transcription factor AP-1. However, the role of GSTA4 in these CRC cells remains unclear. In this study, we investigated the roles of GSTA4 in the CRC cells by inactivating GSTA4 in HCT116 human CRC cells (Defined as HCT116^ΔGSTA4) using the CRISPR/Cas9 gene editing. Cell proliferation, clonogenicity, and susceptibility to chemotherapeutic drugs were analyzed in vitro and in a xenograft model. The results showed that loss of GSTA4 significantly decreased cell proliferation and clonogenicity, whereas it increased intracellular reactive oxygen species and cell susceptibility to 5-fluorouracil (5-FU) and oxaliplatin. Additionally, exposure of HCT116^ΔGSTA4 cells to 5-FU increased the expression of γH2AX, a hallmark of double-stranded DNA breaks. In contrast, no remarkably increased γH2AX was noted in oxaliplatin-treated HCT116^ΔGSTA4 cells compared with HCT116 cells. Moreover, loss of GSTA4 blocked the AKT and p38 MAPK pathways, leading to proliferative suppression. Finally, the xenograft model showed decreased tumor size for HCT116^ΔGSTA4 cells compared with HCT116 cells, confirming in vitro findings. These findings suggest that GSTA4 is capable of promoting proliferation, tumorigenesis, and chemoresistance and is a potential target for CRC therapy.

TXN inhibitor impedes radioresistance of colorectal cancer cells with decreased ALDH1L2 expression via TXN/NF-κB signaling pathway

Background

Colorectal cancer (CRC) is prevalent worldwide and is often challenged by treatment failure and recurrence due to resistance to radiotherapy. Here, we aimed to identify the elusive underlying molecular mechanisms of radioresistance in CRC.

Methods

Weighted gene co-expression network analysis was used to identify potential radiation-related genes. Colony formation and comet assays and multi-target single-hit survival and xenograft animal models were used to validate the results obtained from the bioinformatic analysis. Immunohistochemistry was performed to examine the clinical characteristics of ALDH1L2. Co-immunoprecipitation, immunofluorescence and flow cytometry were used to understand the molecular mechanisms underlying radioresistance.

Results

Bioinformatic analysis, in vitro, and in vivo experiments revealed that ALDH1L2 is a radiation-related gene, and a decrease in its expression induces radioresistance in CRC cells by inhibiting ROS-mediated apoptosis. Patients with low ALDH1L2 expression exhibit resistance to radiotherapy. Mechanistically, ALDH1L2 interacts with thioredoxin (TXN) and regulates the downstream NF-κB signaling pathway. PX-12, the TXN inhibitor, overcomes radioresistance due to decreased ALDH1L2.

Conclusions

Our results provide valuable insights into the potential role of ALDH1L2 in CRC radiotherapy. We propose that the simultaneous application of TXN inhibitors and radiotherapy would significantly ameliorate the clinical outcomes of patients with CRC having low ALDH1L2.

Auranofin and its analogs as prospective agents for the treatment of colorectal cancer

Today colorectal cancer (CRC) is one of the leading causes of cancer death worldwide. This disease is poorly chemo-sensitive toward the existing medical treatments so that new and more effective therapeutic agents are urgently needed and intensely sought. Platinum drugs, oxaliplatin in particular, were reported to produce some significant benefit in CRC treatment, triggering the general interest of medicinal chemists and oncologists for metal-based compounds as candidate anti-CRC drugs. Within this frame, gold compounds and, specifically, the established antiarthritic drug auranofin with its analogs, form a novel group of promising anticancer agents. Owing to its innovative mechanism of action and its favorable pharmacological profile, auranofin together with its derivatives are proposed here as novel experimental agents for CRC treatment, capable of overcoming resistance to platinum drugs. Some encouraging results in this direction have already been obtained. A few recent studies demonstrate that the action of auranofin may be further potentiated through the preparation of suitable pharmaceutical formulations capable of protecting the gold pharmacophore from unselective reactivity or through the design of highly synergic drug combinations. The perspectives of the research in this field are outlined.

Are we still on the right path(way)?: the altered expression of the pentose phosphate pathway in solid tumors and the potential of its inhibition in combination therapy

INTRODUCTION

The pentose phosphate pathway (PPP) branches from glycolysis and is crucial for cell growth, since it provides necessary compounds for anabolic reactions, nucleotide synthesis, and detoxification of reactive-oxygen-species (ROS). Overexpression of PPP enzymes has been reported in multiple cancer types and linked to therapy resistance, making their inhibition interesting targets for anti-cancer therapies.

AREAS COVERED

This review summarizes the extent of PPP upregulation across different cancer types, and the non-metabolic functions that PPP-enzymes might contribute to cancer initiation and maintenance. The effects of PPP-inhibition and their combinations with chemotherapeutics are summarized. We searched the databases provided by the University of Amsterdam to characterize the altered expression of the PPP across different cancer types, and to identify the effects of PPP-inhibition.

EXPERT OPINION

It can be concluded that there are synergistic and additive effects of PPP-inhibition and various classes of chemotherapeutics. These effects may be attributed to the increased susceptibility to ROS. However, the toxicity, low efficacy, and off-target effects of PPP-inhibitors make application in clinical practice challenging. Novel inhibitors are currently being developed, which could make PPP-inhibition a potential therapeutic strategy in the future, especially in combination with conventional chemotherapeutics and the inhibition of other metabolic pathways.

Potential Clinical Applications of Exosomal Circular RNAs: More than Diagnosis

Exosomes are small vesicles derived from cells used as cell-to-cell communication goods in numerous diseases including tumorigenesis, neurological diseases, cardiovascular diseases and other diseases. Circular RNAs (circRNAs) are an innovative constituent of non-coding endogenous RNAs generated through backsplicing, catalyzed by RNA polymerase Ⅱ. These non-coding RNAs have been suggested to control gene expression through miRNA sponging, RNA-binding protein regulation and translational capabilities. Genome-wide RNA sequence analyses observed that circRNAs were stably improved in exosomes in association to parental cells. Little attention has been dedicated to exosomal circRNAs (exo-circRNAs). However, research has demonstrated that exo-circRNAs may have important regulatory functions because of their stability in cells and within exosomes. If well understood, the precise roles and mechanisms of exo-circRNAs might surge the impending clinical applications of these molecules as markers in the identification, prediction and treatment of various diseases. In this review, we outline recent findings regarding exo-circRNAs which includes their functions and highlights their potential applications and therapeutic targets in human diseases.

Risk factors for developing peritoneal metastases after curative surgery for colorectal cancer: A systematic review and meta-analysis

AIM

Proactive detection and treatment strategies have achieved encouraging survival outcomes for patients with early peritoneal metastases (PM), but these costly and invasive approaches can only be applied to selected high-risk patients. This meta-analysis aimed to identify the risk factors for metachronous PM after curative surgery for colorectal cancer (CRC).

METHOD

The study was registered at PROSPERO (CRD42020219187). Databases were searched for studies comparing clinical and histopathological characteristics between patients with metachronous peritoneal metastases from colorectal cancer (pmCRC) and patients without (non-pmCRC).

RESULTS

Thirty-six studies were included. Metachronous PM were positively associated with perforation (OR 1.920; 95% CI 1.144-3.223; P = 0.014), poor differentiation (OR 2.291; 1.603-3.275; P < 0.001), T4 (OR 2.897; 1.248-6.726; P = 0.013), N1-2 (OR 3.429; 2.684-4.381; P < 0.001), mucinous adenocarcinoma (OR 4.175; 1.798-9.692; P = 0.001), obstruction (OR 4.467; 1.919-10.398; P = 0.001), synchronous ovarian metastases (OR 5.005; 1.140-21.977; P = 0.033), positive peritoneal carcinoembryonic antigen mRNA (OR 9.472; 3.643-24.631; P < 0.001), elevated serum carcinoembryonic antigen (preoperative group, OR 3.545, 1.486-8.459, P = 0.004; postoperative group, OR 13.673, 2.222-84.129, P = 0.005), elevated serum cancer antigen 19-9 (preoperative group, OR 5.281, 2.146-12.994, P < 0.001; postoperative group, OR 18.646, 6.429-54.083, P < 0.001) and positive peritoneal cytology (OR 25.884; 11.372-58.913; P < 0.001).

CONCLUSION

These evidence-based risk factors are conducive to designing early detection and proactive treatment strategies, enabling precision medicine.

Inhibition of PI3K/AKT signaling via ROS regulation is involved in Rhein-induced apoptosis and enhancement of oxaliplatin sensitivity in pancreatic cancer cells

Several natural products have been demonstrated to both enhance the anti-tumor efficacy and alleviate the side effects of conventional chemotherapy drugs. Rhein, a main constituent of the Chinese herb rhubarb, has been shown to induce apoptosis in various cancer types. However, the exact pharmacological mechanisms controlling the influence of Rhein on chemotherapy drug effects in pancreatic cancer (PC) remain largely undefined. In this study, we found that Rhein inhibited the growth and proliferation of PC cells through G1 phase cell cycle arrest. Moreover, Rhein induced caspase-dependent mitochondrial apoptosis of PC cells through inactivation of the PI3K/AKT pathway. Combination treatment of Rhein and oxaliplatin synergistically enhanced apoptosis of PC cells through increased generation of intracellular reactive oxygen species (ROS) and inactivation of the PI3K/AKT pathway. Pre-treatment with the ROS scavenger N-acetyl-L-cysteine attenuated the combined treatment-induced apoptosis and restored the level of phosphorylated AKT, indicating that ROS is an upstream regulator of the PI3K/AKT pathway. The combination therapy also exhibited stronger anti-tumor effects compared with single drug treatments in vivo. Taken together, these data demonstrate that Rhein can induce apoptosis and enhance the oxaliplatin sensitivity of PC cells, suggesting that Rhein may be an effective strategy to overcome drug resistance in the chemotherapeutic treatment of PC.

A 3D View of Colorectal Cancer Models in Predicting Therapeutic Responses and Resistance

Although there have been many advances in recent years for the treatment of colorectal cancer (CRC), it still remains the third most common cause of cancer-related deaths worldwide. Many patients with late stage CRC display resistance to multiple different therapeutics. An important aspect in developing effective therapeutics for CRC patients is understanding the interactions that take place in the tumor microenvironment (TME), as it has been shown to contribute to drug resistance in vivo. Much research over the past 100 years has focused on 2D monolayer cultures or in vivo studies, however, the efficacy in translating these to the clinic is very low. More recent studies are turning towards developing an effective 3D model of CRC that is clinically relevant, that can recapitulate the TME in vitro and bridge the gap between 2D cultures and in vivo studies, with the aim of reducing the use of animal models in the future. This review summarises the advantages and limitations of different 3D CRC models. It emphasizes how different 3D models may be optimised to study cellular and extracellular interactions that take place in the TME of CRC in an effort to allow the development of more translatable effective treatment options for patients.