Oxaliplatin induces different cellular and molecular chemoresistance patterns in colorectal cancer cell lines of identical origins

CHD1L Inhibitor OTI-611 Synergizes with Chemotherapy to Enhance Antitumor Efficacy and Prolong Survival in Colorectal Cancer Mouse Models

Colorectal cancer (CRC) is one of the most prevalent and deadly forms of cancer. It is universally treated with a combination of the DNA damaging chemotherapy drugs irinotecan, 5-Fluorouracil (5-FU), and oxaliplatin. CHD1L is a novel oncogene that plays critical roles in chromatin remodeling and DNA damage repair, as well as the regulation of malignant gene expression. We show that an inhibitor of CHD1L, OTI-611, when combined with chemotherapy significantly increases DNA damage in CRC cell lines. OTI-611 also synergizes with SN-38, 5-FU, and oxaliplatin in killing CRC tumor organoids. We also demonstrate that, as in breast cancer, OTI-611 traps CHD1L, PARP1, and PARP2 onto chromatin. The entrapment of CHD1L causes the deprotection of PAR chains in the nucleus, ultimately resulting in cell death by CHD1Li-mediated PARthanatos, as measured by AIF translocation to the nucleus. Finally, the combination of low doses of OTI-611 with irinotecan significantly reduces tumor volume and extends survival in CRC xenograft mouse models compared to irinotecan alone. The combination of standard of care chemotherapy drugs with CHD1Li represents a promising advancement in future therapeutic strategies for CRC and other cancers driven by CHD1L.

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.

Licochalcone B Induces ROS-Dependent Apoptosis in Oxaliplatin-Resistant Colorectal Cancer Cells via p38/JNK MAPK Signaling

Licochalcone B (LCB) exhibits anticancer activity in oral cancer, lung cancer, and hepatocellular carcinoma cells. However, little is known about its antitumor mechanisms in human oxaliplatin-sensitive and -resistant colorectal cancer (CRC) cells. The purpose of the present study was to investigate the antitumor potential of LCB against human colorectal cancer in vitro and analyze its molecular mechanism of action. The viability of CRC cell lines was evaluated using the MTT assay. Flow cytometric analyses were performed to investigate the effects of LCB on apoptosis, cell cycle distribution, reactive oxygen species (ROS), mitochondrial membrane potential (MMP) dysfunction, and multi-caspase activity in CRC cells. The results demonstrated that LCB induced a reduction in cell viability, apoptosis, G2/M cell cycle arrest, ROS generation, MMP depolarization, activation of multi-caspase, and JNK/p38 MAPK. However, p38 (SB203580) and JNK (SP600125) inhibitors prevented the LCB-induced reduction in cell viability. The ROS scavenger N-acetylcysteine (NAC) inhibited LCB-induced reduction in cell viability, apoptosis, cell cycle arrest, ROS generation, MMP depolarization, and multi-caspase and JNK/p38 MAPK activities. Taken together, LCB has a potential therapeutic effect against CRC cells through the ROS-mediated JNK/p38 MAPK signaling pathway. Therefore, we expect LCB to have promising potential as an anticancer therapeutic and prophylactic agent.

The role of autophagy in the treatment of colon cancer by chlorin e6 photodynamic therapy combined with oxaliplatin

BACKGROUND

Photodynamic therapy is a tumour treatment method. Its mechanism mainly induces apoptosis, autophagy, and other ways to cause cell death. Therefore, this study aims to evaluate the therapeutic effect of chlorine e6 photodynamic therapy (Ce6-PDT) combined with oxaliplatin (L-OHP) in colon cancer and to investigate the role of autophagy in L-OHP treatment and Ce6-PDT combined with L-OHP in colon cancer.

METHODS

CCK-8 assay, Scratch wound healing assay, and Western Blot (WB) were used to identify drug-resistant colon cancer cell line SW620/L-OHP. Annexin V/FITC assay, laser confocal double immunofluorescence staining method and WB were employed to investigate the apoptosis and autophagy changes in Ce6-PDT combined with L-OHP.

RESULTS

Drug resistance cells SW620/L-OHP were developed under the continuous multi-generation of L-OHP treatment, and the expression of ATP-binding cassette subfamily B member 1 (ABCB1) and ATG5 proteins were increased. The results of immunofluorescence showed that LC3B accumulated in SW620 cells and SW620/L-OHP cells under the treatment of L-OHP. The WB results indicated that LC3B and ATG5 protein expression was increasing in SW620 cells and SW620/L-OHP cells. Inhibition of L-OHP-induced autophagy reduces SW620 cells and SW620/L-OHP cells' viability while increasing apoptosis and the Pro Caspase-3 protein expression. The combination of Ce6-PDT and L-OHP decreased the cell viability, the cell migration ability, the Bcl-2 protein expression, and increased the apoptosis rate, Pro Caspase-3 protein expression in SW620 cells.

CONCLUSIONS

L-OHP can cause SW620 cells drug resistance. Autophagy plays a protective role in the L-OHP treatment of SW620 cells and SW620/L-OHP cells, and inhibition of autophagy can increase the efficacy of L-OHP. Ce6-PDT combined with L-OHP can further improve the tumor's therapeutic effect, and autophagy inhibition can improve the efficacy of combined therapy.

Computational Tactics for Precision Cancer Network Biology

Network biology has garnered tremendous attention in understanding complex systems of cancer, because the mechanisms underlying cancer involve the perturbations in the specific function of molecular networks, rather than a disorder of a single gene. In this article, we review the various computational tactics for gene regulatory network analysis, focused especially on personalized anti-cancer therapy. This paper covers three major topics: (1) cell line's (or patient's) cancer characteristics specific gene regulatory network estimation, which enables us to reveal molecular interplays under varying conditions of cancer characteristics of cell lines (or patient); (2) computational approaches to interpret the multitudinous and massive networks; (3) network-based application to uncover molecular mechanisms of cancer and related marker identification. We expect that this review will help readers understand personalized computational network biology that plays a significant role in precision cancer medicine.

GSDMD-dependent pyroptotic induction by a multivalent CXCR4-targeted nanotoxin blocks colorectal cancer metastases

Colorectal cancer (CRC) remains the third cause of cancer-related mortality in Western countries, metastases are the main cause of death. CRC treatment remains limited by systemic toxicity and chemotherapy resistance. Therefore, nanoparticle-mediated delivery of cytotoxic agents selectively to cancer cells represents an efficient strategy to increase the therapeutic index and overcome drug resistance. We have developed the T22-PE24-H6 therapeutic protein-only nanoparticle that incorporates the exotoxin A from Pseudomonas aeruginosa to selectively target CRC cells because of its multivalent ligand display that triggers a high selectivity interaction with the CXCR4 receptor overexpressed on the surface of CRC stem cells. We here observed a CXCR4-dependent cytotoxic effect for T22-PE24-H6, which was not mediated by apoptosis, but instead capable of inducing a time-dependent and sequential activation of pyroptotic markers in CRC cells in vitro. Next, we demonstrated that repeated doses of T22-PE24-H6 inhibit tumor growth in a subcutaneous CXCR4⁺ CRC model, also through pyroptotic activation. Most importantly, this nanoparticle also blocked the development of lymphatic and hematogenous metastases, in a highly aggressive CXCR4⁺ SW1417 orthotopic CRC model, in the absence of systemic toxicity. This targeted drug delivery approach supports for the first time the clinical relevance of inducing GSDMD-dependent pyroptosis, a cell death mechanism alternative to apoptosis, in CRC models, leading to the selective elimination of CXCR4⁺ cancer stem cells, which are associated with resistance, metastases and anti-apoptotic upregulation.

Aldehyde Dehydrogenase 2 Family Member (ALDH2) Is a Therapeutic Index for Oxaliplatin Response on Colorectal Cancer Therapy with Dysfunction p53

Oxaliplatin resistance is a major issue in the treatment of p53 mutant colorectal cancer (CRC). Finding the specific biomarkers would improve therapeutic efficacy of patients with CRC. In order to figure out the biomarker for CRC patients with mutant p53 access oxaliplatin, a Gene Expression Omnibus dataset (GSE42387) was used to determine differentially expressed genes (DEGs). The Search Tool for the Retrieval of Interacting Genes (STRING) and Cytoscape software were used to predict protein-protein interactions. The Database for Annotation, Visualization, and Integrated Discovery online tool was used to group the DEGs into their common pathways. 138 DEGs were identified with 46 upregulated and 92 downregulated. In the PPI networks, 7 of the upregulated genes and 13 of the downregulated genes were identified as hub genes (high degrees). Four hub genes, aldehyde dehydrogenase 2 family member (ALDH2), aldo-keto reductase family 1 member B1 (AKR1B1), aldo-keto reductase family 1 member B10 (AKR1B10), and monoglyceride lipase (MGLL) were enriched in the most significant pathway, glycerolipid metabolism. Further, we found that low expression of ALDH2 is correlated with poor overall survival and oxaliplatin resistance. Finally, we found that combined treatment with ALDH2 inhibitor and oxaliplatin will reduce the sensitivity to oxaliplatin in p53 mutant HT29 cells. In conclusion, we demonstrate that ALDH2 may be a biomarker for oxaliplatin resistance status in CRC patients and bring new insight into treatment strategy for p53 mutant CRC patients.

Stress Granules in the Anti-Cancer Medications Mechanism of Action: A Systematic Scoping Review

Stress granule (SG) formation is a well-known cellular mechanism for minimizing stress-related damage and increasing cell survival. In addition to playing a critical role in the stress response, SGs have emerged as critical mediators in human health. It seems logical that SGs play a key role in cancer cell formation, development, and metastasis. Recent studies have shown that many SG components contribute to the anti-cancer medications' responses through tumor-associated signaling pathways and other mechanisms. SG proteins are known for their involvement in the translation process, control of mRNA stability, and capacity to function in both the cytoplasm and nucleus. The current systematic review aimed to include all research on the impact of SGs on the mechanism of action of anti-cancer medications and was conducted using a six-stage methodological framework and the PRISMA guideline. Prior to October 2021, a systematic search of seven databases for eligible articles was performed. Following the review of the publications, the collected data were subjected to quantitative and qualitative analysis. Notably, Bortezomib, Sorafenib, Oxaliplatin, 5-fluorouracil, Cisplatin, and Doxorubicin accounted for the majority of the medications examined in the studies. Overall, this systematic scoping review attempts to demonstrate and give a complete overview of the function of SGs in the mechanism of action of anti-cancer medications by evaluating all research.

Chemosensitivity analysis and study of gene resistance on tumors and cancer stem cell isolates from patients with colorectal cancer

Colorectal cancer (CRC) is one of the main causes of mortality. Recent studies suggest that cancer stem cells (CSCs) can survive after chemotherapy and promote tumor invasiveness and aggression. According to a higher hierarchy complexity of CSC, different protocols for isolation, expansion, and characterization have been used; however, there are no available resistance biomarkers that allow predicting the clinical response of treatment 5‑fluorouracil (5FU) and oxaliplatin. Therefore, the primary aim of the present study was to analyze the expression of gene resistance on tumors and CSC‑derived isolates from patients CRC. In the present study, adenocarcinomas of the colon and rectum (CRAC) were classified based on an in vitro adenosine triphosphate‑based chemotherapy response assay, as sensitive and resistant and the percentage of CD24 and CD44 markers are evaluated by immunohistochemistry. To isolate resistant colon‑CSC, adenocarcinoma tissues resistant to 5FU and oxaliplatin were evaluated. Finally, all samples were sequenced using a custom assay with chemoresistance‑associated genes to find a candidate gene on resistance colon‑CSC. Results showed that 59% of the CRC tissue analyzed was resistant and had a higher percentage of CD44 and CD24 markers. An association was found in the expression of some genes between the tumor‑resistant tissue and CSC. Overall, isolates of the CSC population CD44+ resistant to 5FU and oxaliplatin demonstrated different expression profiles; however, the present study was able to identify overexpression of the KRT‑18 gene, in most of the isolates. In conclusion, the results of the present study showed overexpression of KRT‑18 in CD44+ cells is associated with chemoresistance to 5FU and oxaliplatin in CRAC.

Ruthenium Complexes: An Alternative to Platinum Drugs in Colorectal Cancer Treatment

Colorectal cancer (CRC) is one of the intimidating causes of death around the world. CRC originated from mutations of tumor suppressor genes, proto-oncogenes and DNA repair genes. Though platinum (Pt)-based anticancer drugs have been widely used in the treatment of cancer, their toxicity and CRC cells' resistance to Pt drugs has piqued interest in the search for alternative metal-based drugs. Ruthenium (Ru)-based compounds displayed promising anticancer activity due to their unique chemical properties. Ru-complexes are reported to exert their anticancer activities in CRC cells by regulating different cell signaling pathways that are either directly or indirectly associated with cell growth, division, proliferation, and migration. Additionally, some Ru-based drug candidates showed higher potency compared to commercially available Pt-based anticancer drugs in CRC cell line models. Meanwhile Ru nanoparticles coupled with photosensitizers or anticancer agents have also shown theranostic potential towards CRC. Ru-nanoformulations improve drug efficacy, targeted drug delivery, immune activation, and biocompatibility, and therefore may be capable of overcoming some of the existing chemotherapeutic limitations. Among the potential Ru-based compounds, only Ru (III)-based drug NKP-1339 has undergone phase-Ib clinical trials in CRC treatment.

A promising naphthoquinone [8-hydroxy-2-(2-thienylcarbonyl)naphtho[2,3-b]thiophene-4,9-dione] exerts anti-colorectal cancer activity through ferroptosis and inhibition of MAPK signaling pathway based on RNA sequencing

Naphthoquinones are naturally occurring metabolites with recognized anti-cancer potential but limited clinical application. This study investigated the molecular mechanism of 8-hydroxy-2-(2-thenoyl)naphtho[2,3-b]thiophene-4,9-dione (1), a new candidate for colorectal cancer (CRC) treatment, using different experimental settings: MTT, clonogenic, wound healing, and cell cycle assays; as well as RNA sequencing. Naphthoquinone 1 selectively reduced the viability and migration of HT-29 cells by G2/M arrest and changes in their transcriptome signature with significant effect on cellular survival, proliferation, angiogenesis, response to interferon, oxidative stress, and immune response. Impact analysis identified ferroptosis and MAPK pathways as significantly affected. In summary, our results suggest that 1 induces the selective death of CRC cells by inducing oxidative stress, ferroptosis, and MAPK inhibition.

Tumor repolarization by an advanced liposomal drug delivery system provides a potent new approach for chemo-immunotherapy

Immunosuppressive cells in the tumor microenvironment allow cancer cells to escape immune recognition and support cancer progression and dissemination. To improve therapeutic efficacy, we designed a liposomal oxaliplatin formulation (PCL8-U75) that elicits cytotoxic effects toward both cancer and immunosuppressive cells via protease-mediated, intratumoral liposome activation. The PCL8-U75 liposomes displayed superior therapeutic efficacy across all syngeneic cancer models in comparison to free-drug and liposomal controls. The PCL8-U75 depleted myeloid-derived suppressor cells and tumor-associated macrophages in the tumor microenvironment. The combination of improved cancer cell cytotoxicity and depletion of immunosuppressive populations of immune cells is attractive for combination with immune-activating therapy. Combining the PCL8-U75 liposomes with a TLR7 agonist induced immunological rejection of established tumors. This combination therapy increased intratumoral numbers of cancer antigen-specific cytotoxic T cells and Foxp3^- T helper cells. These results are encouraging toward advancing liposomal drug delivery systems with anticancer and immune-modulating properties into clinical cancer therapy.

Microarray Analysis of Gene Expression Involved in Butyrate-Resistant Colorectal Carcinoma HCT116 Cells

BACKGROUND

Resistance to chemotherapeutic agents is usually found in cancer stem cells (CSCs) and cancer stem-like cells that are often regarded as the target for cancer monitoring. However, the different patterns of their transcriptomic profiling is still unclear.

OBJECTIVE

This study aims to illustrate the transcriptomic profile of CSCs and butyrate-resistant colorectal carcinoma cells (BR-CRCs), by comparing them with parental colorectal cancer (CRC) cells in order to identify distinguishing transcription patterns of the CSCs and BR-CRCs.

METHODS

Parental CRC cells HCT116 (HCT116-PT) were cultured and induced to establish the butyrate resistant cell model (HCT116-BR). Commercial enriching of the HCT116-CSCs were grown in a tumorsphere suspension culture, which was followed firstly by the assessment of butyrate tolerance using MTT and PrestoBlue. Then their gene expression profiling was analyzed by microarray.

RESULTS

The results showed that both butyrate-resistant HCT116 cells (HCT116-BR) and HCT116-CSCs were more tolerant a butyrate effects than HCT116-PT cells. Differentially expressed gene profiles exhibited that IFI27, FOXQ1, PRF1, and SLC2A3 genes were increasingly expressed in CSCs, and were dramatically overexpressed in HCT116-BR cells when compared with HCT116-PT cells. Moreover, PKIB and LOC399959 were downregulated both in HCT116-CSCs and HCT116-BR cells.

CONCLUSION

Our findings shed light on the transcriptomic profiles of chemoresistant CRC cells. This data should be useful for further study to provide guidelines for clinical prognosis to determine the guidelines for CRC treatment, especially in patients with chemoresistance and designing novel anti-neoplastic agents.

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

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

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

Oxaliplatin (OHP) treatment of colorectal cancer (CRC) frequently leads to resistance. OHP resistance was induced in CRC cell lines LoVo-92 and LoVo-Li and a platinum-sensitive ovarian cancer cell line, A2780, and related to cellular platinum accumulation, platinum-DNA adducts, transporter expression, DNA repair genes, gene expression arrays, and array-CGH profiling. Pulse (4 h, 4OHP) and continuous exposure (72 h, cOHP) resulted in 4.0 to 7.9-fold and 5.0 to 11.8-fold drug resistance, respectively. Cellular oxaliplatin accumulation and DNA-adduct formation were decreased and related to OCT1-3 and ATP7A expression. Gene expression profiling and pathway analysis showed significantly altered p53 signaling, xenobiotic metabolism, role of BRCA1 in DNA damage response, and aryl hydrocarbon receptor signaling pathways, were related to decreased ALDH1L2, Bax, and BBC3 (PUMA) and increased aldo-keto reductases C1 and C3. The array-CGH profiles showed focal aberrations. In conclusion, OHP resistance was correlated with total platinum accumulation and OCT1-3 expression, decreased proapoptotic, and increased anti-apoptosis and homologous repair genes.

Connexin 32 downregulation is critical for chemoresistance in oxaliplatin-resistant HCC cells associated with EMT

Background: Oxaliplatin (OXA)-based chemotherapy is critical in the management of advanced hepatocellular carcinoma (HCC); however, acquired drug resistance has largely restricted its clinical efficacy. This study aims to explore the key mechanisms and regulatory factors determining chemosensitivity in HCC.

Methods: We developed OXA-resistant (OR) HCC cells and used multiple methods, including real-time RT-PCR, Western blot, immunofluorescence, transwell invasion assay, wound-healing assay, MTT assay, gene transfection, and immunohistochemistry to achieve our goals.

Results: We found that OR HCC cells showed a typical epithelial–mesenchymal transition (EMT) phenotype. Meanwhile, the expression of Cx32, a major member of the liver connexin (Cx) family, was lowly expressed in OR HCC cells. Downregulation of Cx32 in parental HCC cells led to EMT induction and thereby reduced OXA cytotoxicity, while Cx32 upregulation in OR HCC cells could reverse the EMT phenotype and partially restore chemosensitivity to OXA. Finally, in human HCC tissue samples, Cx32 was positively correlated with the expression of the EMT marker E-cadherin and negatively correlated with the expression of Vimentin.

Conclusion: Our findings demonstrated that downregulation of Cx32 may be an important determinant for HCC cells to acquire EMT-related acquired drug resistance to OXA, and targeting Cx32 could be a novel strategy to overcome OXA resistance in HCC.

Acid ceramidase inhibition sensitizes human colon cancer cells to oxaliplatin through downregulation of transglutaminase 2 and β1 integrin/FAK-mediated signalling

Acid ceramidase (ASAH1) has been implicated in the progression and chemoresistance in different cancers. Its role in colon cancer biology and response to standard chemotherapy has been poorly addressed so far. Here, we have investigated ASAH1 expression at the protein level in human colon cancer cell lines and tissues from colon cancer patients, and have examined in vitro the possible link between ASAH1 expression and functional activity of p53 protein whose inactivation is associated with the progression from adenoma to malignant tumour in colon cancer. Finally, we have explored the role of ASAH1 in response and resistance mechanisms to oxaliplatin (OXA) in HCT 116 colon cancer cells. We have demonstrated that human colon cancer cells and colorectal adenocarcinoma tissues constitutively express ASAH1, and that its expression is higher in tumour tissues than in normal colonic mucosa. Furthermore, we found an inverse correlation between ASAH1 expression and p53 functional activity. Obtained data revealed that ASAH1 was involved in HCT 116 cell response to OXA and that anti-proliferative, pro-apoptotic, anti-migratory and anti-clonogenic effects of OXA could be significantly increased by combination treatment with ASAH1 inhibitor carmofur. Increased OXA sensitivity was associated with downregulation of signalling involved in acquired resistance to OXA in colon cancer, in particular transglutaminase 2 and β1 integrin/FAK, which resulted in the suppression of NF-κB and Akt. Thus, combination of OXA with ASAH1 inhibitors could be a promising strategy to counter chemoresistance and improve treatment outcome in advanced colon cancer.

Novel Palladium(II) Complexes that Influence Prominin-1/CD133 Expression and Stem Cell Factor Release in Tumor Cells

New Pd(II) complexes of 1,7-bis(2-methoxyphenyl)hepta-1,6-diene-3,5-dione were synthesized and structurally characterized. The complexes were tested in vitro on human colon and hepatic carcinoma cell lines, normal hepatic cells and hematopoietic progenitor cells. Biological tests proved that Pd(II) complexes 1 and 2 (containing a curcumin derivative) exhibit a strong in vitro antitumor effect against the cells derived from human colorectal carcinoma and the hepatic metastasis of a colorectal carcinoma. Complex 1 has an outstanding inhibitory effect against BRAF-mutant colon carcinoma and hepatocarcinoma cell growth; 1 and 2 are both more active than the free ligand and have the capacity to trigger early apoptotic processes. By flow cytometric measurements, an important decrease of prominin-1 (CD133) molecule expression on tumor cells membrane was identified in cell populations subjected to 1 and 2. Quantitative immune enzymatic assay proved restrictions in stem cell factor (SCF) release by treated tumor cells. Although less cytotoxic, the free ligand inhibits the surface marker CD133 expression in hepatocarcinoma cells, and in HT-29 colon carcinoma. The new synthesized Pd(II) complexes 1 and 2 exhibit an important potential through their selective cytotoxic activity and by targeting the stem-like tumor cell populations, which leads to the tumor growth arrest and prevention of metastasis.

Epithelial to mesenchymal transition is associated with rapamycin resistance

Rapamycin analogues have antitumor efficacy in several tumor types, however few patients demonstrate tumor regression. Thus, there is a pressing need for markers of intrinsic response/resistance and rational combination therapies. We hypothesized that epithelial-to-mesenchymal transition (EMT) confers rapamycin resistance. We found that the epithelial marker E-cadherin protein is higher in rapamycin sensitive (RS) cells and mesenchymal breast cancer cell lines selected by transcriptional EMT signatures are less sensitive to rapamycin. MCF7 cells, transfected with constitutively active mutant Snail, had increased rapamycin resistance (RR) compared to cells transfected with wild-type Snail. Conversely, we transfected two RR mesenchymal cell lines-ACHN and MDA-MB-231-with miR-200b/c or ZEB1 siRNA to promote mesenchymal-to-epithelial transition. This induced E-cadherin expression in both cell lines, and ACHN demonstrated a significant increase in RS. Treatment of ACHN and MDA-MB-231 with trametinib modulated EMT in ACHN cells in vitro. Treatment of MDA-MB-231 and ACHN xenografts with trametinib in combination with rapamycin resulted in significant growth inhibition in both but without an apparent effect on EMT. Future studies are needed to determine whether EMT status is predictive of sensitivity to rapalogs and to determine whether combination therapy with EMT modulating agents can enhance antitumor effects of PI3K/mTOR inhibitors.

LoVo colon cancer cells resistant to oxaliplatin overexpress c-MET and VEGFR-1 and respond to VEGF with dephosphorylation of c-MET

Oxaliplatin-resistant LoVo colon cancer cells overexpressing c-MET and VEGFR-1 were selected to study several signaling pathways involved in chemoresistance, as well as the effect of increasing amounts of VEGF in the regulation of c-MET. In comparison with chemosensitive LoVo colon cancer cells, oxaliplatin-resistant cells (LoVoR) overexpress and phosphorylate c-MET, upregulate the expression of transmembrane and soluble VEGFR-1 and, unexpectedly, downregulate VEGF. In addition, LoVoR cells activate other transduction pathways involved in chemoresistance such as Akt, β-catenin-TCF4 and E-cadherin. While c-MET is phosphorylated in LoVoR cells expressing low levels of VEGF, c-MET phosphorylation decreases when recombinant VEGF is added into the culture medium. Inhibition of c-MET by VEGF is mediated by VEGFR-1, since phosphorylation of c-MET in the presence of VEGF is restored after silencing VEGFR-1. Dephosphorylation of c-MET by VEGF suggests that tumors coexpressing VEGFR-1 and c-MET may activate c-MET as a result of anti-VEGF therapy.

Curcumin mediates oxaliplatin-acquired resistance reversion in colorectal cancer cell lines through modulation of CXC-Chemokine/NF-κB signalling pathway

Resistance to oxaliplatin (OXA) is a complex process affecting the outcomes of metastatic colorectal cancer (CRC) patients treated with this drug. De-regulation of the NF-κB signalling pathway has been proposed as an important mechanism involved in this phenomenon. Here, we show that NF-κB was hyperactivated in in vitro models of OXA-acquired resistance but was attenuated by the addition of Curcumin, a non-toxic NF-κB inhibitor. The concomitant combination of Curcumin + OXA was more effective and synergistic in cell lines with acquired resistance to OXA, leading to the reversion of their resistant phenotype, through the inhibition of the NF-κB signalling cascade. Transcriptomic profiling revealed the up-regulation of three NF-κB-regulated CXC-chemokines, CXCL8, CXCL1 and CXCL2, in the resistant cells that were more efficiently down-regulated after OXA + Curcumin treatment as compared to the sensitive cells. Moreover, CXCL8 and CXCL1 gene silencing made resistant cells more sensitive to OXA through the inhibition of the Akt/NF-κB pathway. High expression of CXCL1 in FFPE samples from explant cultures of CRC patients-derived liver metastases was associated with response to OXA + Curcumin. In conclusion, we suggest that combination of OXA + Curcumin could be an effective treatment, for which CXCL1 could be used as a predictive marker, in CRC patients.

Molecular Dissection of Induced Platinum Resistance through Functional and Gene Expression Analysis in a Cell Culture Model of Bladder Cancer

We report herein the development, functional and molecular characterization of an isogenic, paired bladder cancer cell culture model system for studying platinum drug resistance. The 5637 human bladder cancer cell line was cultured over ten months with stepwise increases in oxaliplatin concentration to generate a drug resistant 5637R sub cell line. The MTT assay was used to measure the cytotoxicity of several bladder cancer drugs. Liquid scintillation counting allowed quantification of cellular drug uptake and efflux of radiolabeled oxaliplatin and carboplatin. The impact of intracellular drug inactivation was assessed by chemical modulation of glutathione levels. Oxaliplatin- and carboplatin-DNA adduct formation and repair was measured using accelerator mass spectrometry. Resistance factors including apoptosis, growth factor signaling and others were assessed with RNAseq of both cell lines and included confirmation of selected transcripts by RT-PCR. Oxaliplatin, carboplatin, cisplatin and gemcitabine were significantly less cytotoxic to 5637R cells compared to the 5637 cells. In contrast, doxorubicin, methotrexate and vinblastine had no cell line dependent difference in cytotoxicity. Upon exposure to therapeutically relevant doses of oxaliplatin, 5637R cells had lower drug-DNA adduct levels than 5637 cells. This difference was partially accounted for by pre-DNA damage mechanisms such as drug uptake and intracellular inactivation by glutathione, as well as faster oxaliplatin-DNA adduct repair. In contrast, both cell lines had no significant differences in carboplatin cell uptake, efflux and drug-DNA adduct formation and repair, suggesting distinct resistance mechanisms for these two closely related drugs. The functional studies were augmented by RNAseq analysis, which demonstrated a significant change in expression of 83 transcripts, including 50 known genes and 22 novel transcripts. Most of the transcripts were not previously associated with bladder cancer chemoresistance. This model system and the associated phenotypic and genotypic data has the potential to identify some novel details of resistance mechanisms of clinical importance to bladder cancer.