BRSK1 confers cisplatin resistance in cervical cancer cells via regulation of mitochondrial respiration

PURPOSE

Although cisplatin-containing chemotherapy has been utilized as a front-line treatment for cervical cancer, intrinsic and acquired resistance of cisplatin remains a major hurdle for the durable and curative therapeutic response. We thus aim to identify novel regulator of cisplatin resistance in cervical cancer cells.

METHODS

Real-time PCR and western blotting analysis were employed to determine the expression of BRSK1 in normal and cisplatin-resistant cells. Sulforhodamine B assay was conducted to assess the sensitivity of cervical cancer cells to cisplatin. Seahorse Cell Mito Stress Test assay was utilized to evaluate the mitochondrial respiration in cervical cancer cells.

RESULTS

BRSK1 expression was upregulated in cisplatin-treated cervical cancer patient tumors and cell lines compared with untreated tumors and cell lines. Depletion of BRSK1 significantly enhanced the sensitivity of both normal and cisplatin-resistant cervical cancer cells to cisplatin treatment. Moreover, BRSK1-mediated regulation of cisplatin sensitivity is conducted by a subpopulation of BRSK1 residing in the mitochondria of cervical cancer cells and is dependent on its kinase enzymatic activity. Mechanistically, BRSK1 confers cisplatin resistance via the regulation of mitochondrial respiration. Importantly, treatment with mitochondrial inhibitor in cervical cancer cells phenocopied the BRSK1 depletion-mediated mitochondria dysfunction and cisplatin sensitization. Of note, we observed that high BRSK1 expression is correlated with poor prognosis in cisplatin-treated cervical cancer patients.

CONCLUSION

Our study defines BRSK1 as a novel regulator of cisplatin sensitivity, identifying that targeting BRSK1-regulated mitochondrial respiration could be a useful approach for enhancing the efficacy of cisplatin-based chemotherapy in cervical cancer patients.

Chemotherapeutic drugs-induced pyroptosis mediated by gasdermin E promotes the progression and chemoresistance of pancreatic cancer

Pyroptosis is closely associated with cancer development; however, the role of pyroptosis in pancreatic ductal adenocarcinoma (PDAC), a fatal malignant tumour with a poor overall survival rate, remains elusive. Here, we explored the mechanism of chemotherapy-induced pyroptosis and elucidated the role of pyroptosis in mediating PDAC progression and chemoresistance. The results demonstrated first- and second-line chemotherapeutic drugs against PDAC, including gemcitabine, irinotecan, 5-fluorouracil, paclitaxel, and cisplatin, induced concurrent pyroptosis and apoptosis. During this process, gasdermin E (GSDME) was cleaved by activated caspase-3, which was accompanied by pro-apoptotic caspase-7/8 activation. GSDME knockdown switched pyroptosis to apoptosis, decreased invasion and migration, and enhanced the sensitivity of PDAC cells to chemotherapy in vitro and in vivo. GSDME was highly expressed in PDAC tissues and positively correlated with histological differentiation and vascular invasion. Furthermore, cells that survived pyroptosis promoted proliferation and invasion and impaired the chemosensitivity of PDAC cells, which was attenuated by the GSDME knockdown. Our findings demonstrated that chemotherapeutics against PDAC induce GSDME-dependent pyroptosis, and GSDME expression positively correlated with PDAC progression and chemoresistance. Targeting GSDME may be a novel approach to overcoming chemoresistance in PDAC.

Targeted downregulation of MYC mediated by a highly efficient lactobionic acid-based glycoplex to enhance chemosensitivity in human hepatocellular carcinoma cells

The chemosensitization of tumor cells by gene therapy represents a promising strategy for hepatocellular carcinoma (HCC) treatment. In this regard, HCC-specific and highly efficient gene delivery nanocarriers are urgently needed. For this purpose, novel lactobionic acid-based gene delivery nanosystems were developed to downregulate c-MYC expression and sensitize tumor cells to low concentration of sorafenib (SF). A library of tailor-made cationic glycopolymers, based on poly(2-aminoethyl methacrylate hydrochloride) (PAMA) and poly(2-lactobionamidoethyl methacrylate) (PLAMA) were synthesized by a straightforward activators regenerated by electron transfer atom transfer radical polymerization. The nanocarriers prepared with PAMA₁₁₄-co-PLAMA₂₀ glycopolymer were the most efficient for gene delivery. These glycoplexes specifically bound to the asialoglycoprotein receptor and were internalized through the clathrin-coated pit endocytic pathway. c-MYC expression was significantly downregulated by MYC short-hairpin RNA (MYC shRNA), resulting in efficient inhibition of tumor cells proliferation and a high levels apoptosis in 2D and 3D HCC-tumor models. Moreover, c-MYC silencing increased the sensitivity of HCC cells to SF (IC₅₀ for MYC shRNA+ SF 1.9 μM compared to 6.9 μM for control shRNA + SF). Overall, the data obtained demonstrated the great potential of PAMA₁₁₄-co-PLAMA₂₀/MYC shRNA nanosystems combined with low doses of SF for the treatment of HCC.

Paraoxonase-2 is upregulated in triple negative breast cancer and contributes to tumor progression and chemoresistance

Triple negative breast cancer (TNBC) displays a high aggressive behavior, tendency to relapse and early metastasize, leading to poor prognosis. The lack of estrogen receptors, and human epidermal growth factor receptor 2, prevents the use of endocrine or molecular targeted therapy, being therapeutical options for TNBC managements mostly limited to surgery, radiotherapy and mainly chemotherapy. While an important number of TNBCs initially responds to chemotherapy, they are prone to develop chemoresistance over the time. Thus, there is an urgent need to identify novel molecular targets to improve the outcome of chemotherapy in TNBC. In this work we focused on the enzyme paraoxonase-2 (PON2) which has been reported to be overexpressed in several tumors contributing to cancer aggressiveness and chemoresistance. Through a case-control study, we analyzed PON2 immunohistochemical expression in breast cancer molecular subtypes Luminal A, Luminal B, Luminal B HER2+, HER2 + and TNBC. Subsequently, we evaluated the in vitro effect of PON2 downregulation on cell proliferation and response to chemotherapeutics. Our results showed that the PON2 expression levels were significantly upregulated in the infiltrating tumors related to the subtypes Luminal A, HER2+ and TNBC compared to the healthy tissue. Furthermore, PON2 downregulation led to a decrease in cell proliferation of breast cancer cells, and significantly enhanced the cytotoxicity of chemotherapeutics on the TNBC cells. Although further analyses are necessary to deeply understand the mechanisms by which the enzyme could participate to breast cancer tumorigenesis, our results seem to demonstrate that PON2 could represent a promising molecular target for TNBC treatment.

Machine learning-based models for genomic predicting neoadjuvant chemotherapeutic sensitivity in cervical cancer

BACKGROUND

The PI3K/Akt pathway involves in regulating resistance to platinum-based neoadjuvant chemotherapy (NACT) in locally advanced cervical cancer (LACC) patients. Single nucleotide polymorphisms (SNPs) reflect the basic genetic variation between individuals. Random forest (RF) is one of the machine-learning models that can predict drug sensitivity with high accuracy. We applied the RF model for genomic prediction of NACT sensitivity in LACC patients.

MATERIALS AND METHODS

A total of 259 LACC patients were separated to two groups (i) effective and (ii) ineffective NACT group, depending on the NACT response. The 24 SNPs in four genes (PTEN, PIK3CA, Akt1, and Akt2) were genotyped by the Sequenom MassArray system in these patients. We implemented the SNPs as the feature to train the RF model, calculated the feature importance using mean decreases in impurity based on the model, and further analyzed the importance of each SNP.

RESULTS

The importance analysis indicated that the top three SNPs (rs4558508, rs1130233, and rs7259541) and the last six loci (rs892120, rs62107593, rs34716810, rs10416620, rs41275748, and rs41275746) were all located in Akt. The patients carrying heterozygous GA in Akt2 rs4558508 had a considerably higher risk of chemoresistance than those carrying GG or AA genotype.

CONCLUSION

The RF model could accurately predict the response to platinum-based NACT of LACC patients. The variables of Akt2 rs4558508 and rs7259541, and Akt1 rs1130233 were major polymorphic loci for NACT inefficiency. The LACC patients carrying heterozygous GA of Akt2 rs4558508 had a significantly increased risk of chemoresistance. Akt was an important gene in PI3K/Akt pathway that could predict the response of platinum-based NACT. The study applied the basis for an individualized approach to LACC patient therapy.

Integrative analyses of biomarkers and pathways for metformin reversing cisplatin resistance in head and neck squamous cell carcinoma cells

OBJECTIVES

In this study, transcriptome sequencing were performed to elucidate the molecular mechanism by which metformin inhibits head and neck squamous cell carcinoma (HNSCC) cells progression and sensitizes HNSCC cells to chemotherapy. We aimed to propose a novel chemotherapeutic approach with high efficacy and few side effects and provide a new strategy for HNSCC treatment.

DESIGN

The effects of metformin on the biological behaviors of HNSCC cells were validated by CCK8 cell proliferation assays, would healing assays and flow cytometric apoptosis assays. The appropriate metformin concentrations for the experimental pretreatment of HNSCC cells were selected based on experimental results, and the treated cells were subjected to transcriptome sequencing. After bioinformatics analysis and intersection with a post-chemotherapy resistance dataset from the GEO database numbered GSE102787, the genes were identified and used to predict potential metformin targets after functional enrichment analysis.

RESULTS

Metformin significantly inhibited the proliferation and migration and induced the apoptosis of Cal27 and FaDu cells. A total of 284 genes that are potentially targeted by metformin during HNSCC cell sensitization were identified by bioinformatics, and ten hub genes with high connectivity were selected. In particular, Fen1 overexpression was associated with poor prognosis in HNSCC patients.

CONCLUSIONS

Our study demonstrates that Fen1 is overexpressed in HNSCC tissues compared with normal tissues and that Fen1 overexpression is a poor prognostic factor in HNSCC patients. Metformin enhances the ability of cisplatin to inhibit HNSCC progression. Further studies are needed to explore the therapeutic value of Fen1 in HNSCC.

[Matrix stiffening related lncRNA SNHG8 regulates chemosensitivity of ovarian cancer]

Extracellular matrix (ECM) has been implicated in tumor progress and chemosensitivity. Ovarian cancer brings a great threat to the health of women with a significant feature of high mortality and poor prognosis. However, the potential significance of matrix stiffness in the pattern of long non-coding RNAs (lncRNAs) expression and ovarian cancer drug sensitivity is still largely unkown. Here, based on RNA-seq data of ovarian cancer cell cultured on substrates with different stiffness, we found that a great amount of lncRNAs were upregulated in stiff group, whereas SNHG8 was significantly downregulated, which was further verified in ovarian cancer cells cultured on polydimethylsiloxane (PDMS) hydrogel. Knockdown of SNHG8 led to an impaired efficiency of homologous repair, and decreased cellular sensitivity to both etoposide and cisplatin. Meanwhile, the results of the GEPIA analysis indicated that the expression of SNHG8 was significantly decreased in ovarian cancer tissues, which was negatively correlated with the overall survival of patients with ovarian cancer. In conclusion, matrix stiffening related lncRNA SNHG8 is closely related to chemosensitivity and prognosis of ovarian cancer, which might be a novel molecular marker for chemotherapy drug instruction and prognosis prediction.

Enhancement of the antitumor effect of 5-fluorouracil with modulation in drug transporters expression using PI3K inhibitors in colorectal cancer cells

AIMS

5-Fluorouracil (5-FU) represents the cornerstone for colorectal cancer therapy. However, resistance to its action is a major hindrance. This study aimed to investigate the effectiveness of suppressing the activity of PI3K/Akt/mTOR signaling pathway on the chemosensitivity of colorectal cancer cells to 5-FU, as well as to delineate the possible underlying cellular mechanisms and the expected modulation in the expression of specific ABC drug transporters.

MAIN METHODS

HCT116 and Caco-2 cells were incubated with 5-FU, LY294002, or PI-103 individually or in combination. Cell viability was monitored using MTT assay. The expression of a panel of drug transporters was evaluated by RT-PCR. Immunofluorescence staining was applied to evaluate the expression pattern of phospho-AKT, phospho-mTOR, and ABGG2. HPLC evaluated the enhancement in the 5-FU cellular uptake. Cell apoptosis was detected by flow cytometry, and cell morphological changes following treatment were inspected under a fluorescence microscope. Additionally, the migration ability of cells following our suggested treatment combination was examined by wound healing assay.

KEY FINDINGS

The results reveal a notable enhancement in the cytotoxicity of a low dose of 5-FU when combined with a PI3K inhibitor (LY294002 or PI-103). This enhancement was influenced by the significant reduction in the expression of p-AKT and p-mTOR and was also mediated by a significant suppression in the expression of ABCG2 and ABCC5. Consequently, we detected an increase in the cellular uptake and concentration of 5-FU in cells treated with this combination rather than a single 5-FU treatment. Our Suggested combination treatment also induced cell apoptosis and reduced the migration ability of cells.

SIGNIFICANCE

Our data provide evidence that survival signaling pathways represent distinctive targets for the enhancement of chemotherapeutic sensitivity. The antitumor efficacy of 5-FU is enhanced when combined with a PI3K inhibitor, and this effect was mediated by alterations in the expression of specific drug transporters.

Inactivation of KDM5A suppresses growth and enhances chemosensitivity in liver cancer by modulating ROCK1/PTEN/AKT pathway

Liver cancer is a kind of malignant tumor with poor sensitivity to chemotherapy. It is urgent to investigate approaches to improve the outcome of chemotherapy. KDM5A has been reported to be an oncogene in various cancers and is associated with drug resistance. However, the functions of KDM5A in chemotherapeutic sensitivity of liver cancer not been well illustrated. In this study, we found that KDM5A was upregulated in liver cancer tissue and cell lines. KDM5A knockdown using a gene interference strategy suppressed the growth of liver cancer in vitro and in vivo. CPI-455, a pharmacological inactivation of KDM5A enhanced the cytotoxicity of cisplatin (CDDP) in liver cells. CPI-455 and CDDP cotreatment resulted in apoptosis and mitochondrial dysfunction. We also found that knockdown or inactivation of KDM5A resulted in the downregulation of ROCK1, an oncogene regulating the activation of the PTEN/AKT signaling pathway. In particular, overexpression of ROCK1 or SF1670, a pharmacological inhibitor of PTEN, alleviated the cytotoxicity of CPI-455 and CDDP cotreatment. In HCCLM3 xenografts, CPI-455 and CDDP cotreatment dramatically inhibited the growth of xenograft tumor compared to CPI-455 or CDDP treatment alone. In conclusion, this study suggested that targeting the inactivation of KDM5A is an efficient strategy to enhance the chemosensitivity of liver cancer cells to CDDP by modulating the ROCK1/PTEN/AKT signaling pathway.

Predicting chemosensitivity based on mini patient-derived xenografts in osteosarcoma patients: A retrospective study

Context

The survival of patients diagnosed with osteosarcoma has not improved in the past three decades because of chemoresistance.

Aim

This study aimed to improve the prognosis of patients with osteosarcoma.

Settings and Design

From January 1, 2018, to June 30, 2019, a total of 14 patients with osteosarcoma were enrolled who underwent mini patient-derived xenograft (mini-PDX) assay in our hospital.

Methods and Materials

We recruited 14 patients with osteosarcoma having acquirable lesions to establish PDX models and examine the sensitivity of nine drugs, including methotrexate (MTX), ifosfamide (IFO), epirubicin, and etoposide. Drug sensitivity was evaluated using the tumor relative proliferation rate (TRPR), and the patients' responses were assessed according to the RECIST 1.1 guidelines.

Statistical Analysis Used

The difference in TRPR was analyzed using a paired t-test, while progression-free survival (PFS) was analyzed using the Kaplan-Meier method.

Results

The mini-PDX results revealed that IFO had a lower tumor proliferation rate than MTX, indicating that IFO was more sensitive in patients with osteosarcoma (38.3% vs. 84.3%, P = 0.031). Thus, the regimen where IFO alternates with doxorubicin and cisplatin was recommended as adjuvant chemotherapy. MTX could replace IFO if the TRPR was better. Finally, 11 patients received adjuvant chemotherapy. A comparison of PFS revealed that sensitive patients with TRPR of <40% had a better prognosis (9.4 months vs. 3.7 months, P = 0.0324).

Conclusions

Chemotherapy based on mini-PDX can improve the survival of patients with osteosarcoma whose TRPR was <40%, and that chemotherapy without MTX could be an alternative for osteosarcoma.

Arterial bicarbonate is associated with hypoxic burden and uncontrolled hypertension in obstructive sleep apnea - The ESADA cohort

OBJECTIVE

Blood bicarbonate concentration plays an important role for obstructive sleep apnea (OSA) patients to maintain acid-base balance. We investigated the association between arterial standard bicarbonate ([HCO3^-]) and nocturnal hypoxia as well as comorbid hypertension in OSA.

METHODS

A cross-sectional analysis of 3329 patients in the European Sleep Apnea Database (ESADA) was performed. Arterial blood gas analysis and lung function test were performed in conjunction with polysomnographic sleep studies. The 4% oxygen desaturation index (ODI), mean and minimum oxygen saturation (SpO₂), and percentage of time with SpO₂ below 90% (T90%) were used to reflect nocturnal hypoxic burden. Arterial hypertension was defined as a physician diagnosis of hypertension with ongoing antihypertensive medication. Hypertensive patients with SBP/DBP below or above 140/90 mmHg were classified as controlled-, uncontrolled hypertension, respectively.

RESULTS

The [HCO3^-] level was normal in most patients (average 24.0 ± 2.5 mmol/L). ODI, T90% increased whereas mean and minimum SpO₂ decreased across [HCO3^-] tertiles (ANOVA, p = 0.030, <0.001, <0.001, and <0.001, respectively). [HCO3^-] was independently associated with ODI, mean SpO₂, minimum SpO₂, and T90% after adjusting for confounders (β value [95%CI]: 1.21 [0.88-1.54], -0.16 [-0.20 to -0.11], -0.51 [-0.64 to -0.37], 1.76 [1.48-2.04], respectively, all p < 0.001). 1 mmol/L elevation of [HCO3^-] was associated with a 4% increased odds of uncontrolled hypertension (OR: 1.04 [1.01-1.08], p = 0.013).

CONCLUSION

We first demonstrated an independent association between [HCO3^-] and nocturnal hypoxic burden as well as uncontrolled hypertension in OSA patients. Bicarbonate levels as an adjunctive measure provide insight into the pathophysiology of hypertension in OSA.

Oncogenic lncRNA MALAT-1 recruits E2F1 to upregulate RAD51 expression and thus promotes cell autophagy and tumor growth in non-small cell lung cancer

INTRODUCTION

LncRNA MALAT-1 expression is involved in regulating activities of non-small-cell lung cancer (NSCLC) cells. This study aimed to investigate the effects of lncRNA MALAT-1 on chemosensitivity of NSCLC cells by regulating autophagy.

METHODS

We first validated the expression of lncRNA MALAT-1 in NSCLC cell lines. NSCLC cell lines with high lncRNA MALAT-1 expression were exposed to doxorubicin (DOX) to assess chemosensitivity. Further LncMAP database retrieval and ChIP, RIP and luciferase activity assays were conducted to explore interplay between lncRNA MALAT-1, RAD51, and E2F1. Immunofluorescence staining was performed to evaluate formation of autophagosomes in NSCLC cells. Ectopic expression and knockdown methods were used for in vitro mechanism experiments and in vivo substantiation.

RESULTS

LncRNA MALAT-1 was overexpressed in NSCLC cells, and could promote NSCLC cell autophagy and inhibit its chemosensitivity. In vitro cell mechanism verification experiments showed that lncRNA MALAT-1 could recruit transcription factor E2F1 to bind to the promoter of RAD51, so as to promote the transcriptional expression of RAD51. In addition, cell function experiments in vitro showed that ectopically expressed lncRNA MALAT-1 promoted NSCLC cell autophagy and inhibited its chemosensitivity, while RAD51 knockdown negated its effect. Finally, in vivo animal experiments confirmed that lncRNA MALAT-1 silencing could impede the tumor growth.

CONCLUSIONS

Taken together, this study revealed that silencing lncRNA MALAT-1 enhanced chemosensitivity of NSCLC cells by promoting autophagy, highlighting a feasible approach to prevent chemoresistance in NSCLC treatment.

Inhibition of secretory leukocyte protease inhibitor (SLPI) promotes the PUMA-mediated apoptosis and chemosensitivity to cisplatin in colorectal cancer cells

BACKGROUND

Aberrant expression of Secretory Leukocyte Protease Inhibitor (SLPI) has been associated with human cancer growth and its suppression was identified as a potential target for anti-cancer drugs, particularly in colorectal cancer. However, the underlying mechanism by which SLPI affected the development of drug resistance in CRC remains unclear.

OBJECTIVE

This study investigated the role of SLPI in the p53-up-regulated modulator of apoptosis (PUMA)-mediated CRC cells' apoptosis and their chemosensitivity to Cisplatin.

METHODS

A series of qRT-PCR and western blot analyses were performed to characterize the expressions of SLPI, PUMA, and Akt in CRC lines. Tunel, transwell, and CCK-8 analyses were monitored to define the impacts of the siRNA-mediated knockdown of SLPI on CRC cell development. Furthermore, in vivo development of CRC was evaluated in nude mice infected with siSLPI or Cisplatin alone or both, and Ki67 and caspase-3 immunohistochemistry assay was monitored on multiple tissue microarray from the same cohort.

RESULTS

Our results showed that SLPI inhibition strongly promoted the expressions of the pro-apoptotic protein PUMA, cleaved-caspase3 and Bax and reduced the cell viability of HT29 and HT116 cell lines in vitro. In addition, siSLPI knockdown effectively suppressed both Akt and FoxO3 proteins and improved the sensitivity to cisplatin chemotherapy. Xenograft tumor assay revealed a lowered growth in mice treated with Cisplatin, while combined treatment of siSLPI achieved more significant anticancer effects than Cisplatin alone.

CONCLUSIONS

Taken together, these findings demonstrated that suppression of SLPI might repress the growth of human colorectal cancer cells both in vitro and in vivo. These results suggested SLPI as a novel resistance factor to Cisplatin, and a combination of Cisplatin and SLPI inhibitor be beneficial for colorectal cancer therapy.

Evidence for heterogeneity in response to treatment in mammary tumors of dogs as happens in humans

Tumors are formed by various clones developed over a long time. This gives rise to a heterogeneous nature. This heterogeneity is the hardest challenge in the treatment of cancers because it is the main reason for drug resistance. This is a well-known fact in human cancer. Therefore, we have reasoned that if the tumor heterogeneity in canine mammary gland tumors (CMGTs) could be shown by an ex vivo assay, which will be used first time in veterinary oncology practice, this could be used further in clinics. To achieve this, twenty-six patients were included in the study. Tumor tissues were obtained from animals during routine surgery. Tumor cells were isolated and seeded ex vivo. The cells were exposed to anticancer drugs that are clinically used. Seven days after the treatment, chemosensitivity has luminometrically been assayed by ATP-tumor chemosensitivity assay (ATP-TCA). It has clearly been shown that all the tumor tissues have responded to treatment differently, implying that heterogeneity exists in mammary tumors. There has also been found that there was a weak to moderate statistically significant correlation between tumor size and drug index. However, there has been no correlation between drug index and metastasis to lymph nodes. Hyperplasic areas had relatively higher PCNA values. The results of our study demonstrate the heterogeneity in responses to in vitro drugs. Clinical trials based on test results and follow-up studies with large numbers of animals are needed to prove that such chemotherapeutic activity assessment tests can be clinically useful in predicting drug responses in CMGTs.

Role of chemosensitivity: Possible pathophysiological mediator of obstructive sleep apnea and type 2 diabetes

Obstructive sleep apnea (OSA) and type 2 diabetes show some mutual promotion of disease development. Variation in chemosensitivity is a key contributor to the pathophysiological mechanisms causing OSA and type 2 diabetes. According to studies conducted thus far, people with OSA or type 2 diabetes may have higher chemoreflex levels, but it is challenging to identify the precise changes because of variations in participant characteristics, the severity of the disease at the time of recruitment, and the small sample sizes in each study. Lowering chemosensitivity may also be viewed as a new issue for individuals with OSA and type 2 diabetes who require personalized care. The purpose of this review was to give an overview of chemosensitivity changes in OSA and glucose metabolism, as well as prospective therapeutic treatments for patients with OSA and type 2 diabetes.

Schizandrin A enhances killing effect of oxaliplatin on colorectal cancer cells

BACKGROUND

Schizandrin A (SchA) has anticancer and multidrug resistance-reversing effects in a variety of tumors, but its effect on oxaliplatin (L-OHP) in colorectal cancer cells is not clear.

AIM

To investigate whether SchA can enhance the killing effect of L-OHP on colorectal cancer cells, and to analyze the possible mechanism involved.

METHODS

Colorectal cancer cells were divided into control group, SchA treatment group, L-OHP treatment group, and SchA + L-OHP treatment group. Cell viability was detected by MTT assay. Cell apoptosis was detected by flow cytometry. The contents of reactive oxygen species (ROS) in cells was detected using a ROS probe. Mitochondrial membrane potential was evaluated by using the 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachloroimidacarbocyanine iodide (JC-1) probe. Western blot was used to detect the expression of B-cell lymphoma 2 (Bcl-2), Bcl-2 associated X protein (Bax), cytochrome c (Cyt c), and cleaved cysteine proteinase-3 (caspase-3) in the cells.

RESULTS

Compared with the L-OHP treatment group, the viability of colorectal cancer cells in the SchA + L-OHP treatment group was significantly decreased, while apoptosis was significantly increased. SchA could enhance ROS accumulation, Bax and cleaved caspase-3 expression, and mitochondrial Cyt c release, and decrease Bcl-2 expression in colorectal cancer cells induced by L-OHP.

CONCLUSION

SchA enhances the killing effect of L-OHP on colorectal cancer cells, and the mechanism may be related to the enhancement of intracellular ROS accumulation and the expression of apoptosis-related proteins.

Correlation between IFNAR1 expression in peripheral blood T lymphocytes and inflammatory cytokines, tumor-infiltrating lymphocytes, and chemosensitivity in patients with colorectal cancer

IFN-α receptor (IFNAR) is critical for maintaining the crosstalk between cancer cells and lymphocytes. We investigated IFNAR1 expression in peripheral blood CD4⁺ and CD8⁺ T cells and explored their relationships with plasma cytokines, chemosensitivity and infiltrated T cells in the tumor microenvironment (TME) of colorectal cancer (CRC). The levels of IFNAR1, IFN-γ, and PD1 in peripheral T cells were tested using flow cytometry. Immunohistochemical staining of IFNAR1 in CRC tissues was performed. A cytometric bead array was used to determine the plasma concentrations of cytokines. In CRC patients, IFNAR1 levels were significantly increased in peripheral blood T cells, and plasma IL-6 levels were also significantly increased. Pearson correlation analysis revealed that IFNAR1 expression in CD8⁺ T cells was negatively associated with plasma IL-2, IFN-γ, and TNFα. IFNAR1 expression in CD4⁺ T cells was positively associated with TME infiltrated levels of CD8⁺ T cells. The levels of CD8⁺ T cells with IFNAR1 and plasma IFN-γ were associated with chemosensitivity. Collectively, IFNAR1 levels in CD4⁺ and CD8⁺ T cells were significantly upregulated in CRC patients and positively associated with T-cell infiltration. IFNAR1 may be a chemotherapy biomarker for predicting response.

SRGAP2 controls colorectal cancer chemosensitivity via regulation of mitochondrial complex I activity

Mitochondrial respiration and metabolism play an important role in the occurrence and development of colorectal cancer (CRC). In this study, we identified a functional pool of SLIT-ROBO Rho GTPase-activating protein 2 (SRGAP2) in the mitochondria of CRC cells as an important regulator of CRC chemosensitivity. We found that SRGAP2 levels were increased in CRC cells in comparison to normal colorectal cells. Loss of mitochondrial SRGAP2 led to significant decrease in mitochondrial respiration and strongly sensitized the CRC cells to chemotherapy drugs. Mechanistically, SRGAP2 physically interacts with mitochondrial complex I and positively modulates its activity. In particular, chemosensitization upon SRGAP2 loss was phenocopied by the treatment of complex I inhibitor. Thus, our results demonstrate that SRGAP2 functions as a key regulator of CRC chemosensitivity, identifying SRGAP2 as a promising therapeutic target to enhance the efficacy of chemotherapy in CRC.

The m6A demethylase ALKBH5-mediated upregulation of DDIT4-AS1 maintains pancreatic cancer stemness and suppresses chemosensitivity by activating the mTOR pathway

Background

Chemoresistance is a major factor contributing to the poor prognosis of patients with pancreatic cancer, and cancer stemness is one of the most crucial factors associated with chemoresistance and a very promising direction for cancer treatment. However, the exact molecular mechanisms of cancer stemness have not been completely elucidated.

Methods

m⁶A-RNA immunoprecipitation and sequencing were used to screen m⁶A-related mRNAs and lncRNAs. qRT-PCR and FISH were utilized to analyse DDIT4-AS1 expression. Spheroid formation, colony formation, Western blot and flow cytometry assays were performed to analyse the cancer stemness and chemosensitivity of PDAC cells. Xenograft experiments were conducted to analyse the tumour formation ratio and growth in vivo. RNA sequencing, Western blot and bioinformatics analyses were used to identify the downstream pathway of DDIT4-AS1. IP, RIP and RNA pulldown assays were performed to test the interaction between DDIT4-AS1, DDIT4 and UPF1. Patient-derived xenograft (PDX) mouse models were generated to evaluate chemosensitivities to GEM.

Results

DDIT4-AS1 was identified as one of the downstream targets of ALKBH5, and recruitment of HuR onto m⁶A-modified sites is essential for DDIT4-AS1 stabilization. DDIT4-AS1 was upregulated in PDAC and positively correlated with a poor prognosis. DDIT4-AS1 silencing inhibited stemness and enhanced chemosensitivity to GEM (Gemcitabine). Mechanistically, DDIT4-AS1 promoted the phosphorylation of UPF1 by preventing the binding of SMG5 and PP2A to UPF1, which decreased the stability of the DDIT4 mRNA and activated the mTOR pathway. Furthermore, suppression of DDIT4-AS1 in a PDX-derived model enhanced the antitumour effects of GEM on PDAC.

Conclusions

The ALKBH5-mediated m⁶A modification led to DDIT4-AS1 overexpression in PDAC, and DDIT-AS1 increased cancer stemness and suppressed chemosensitivity to GEM by destabilizing DDIT4 and activating the mTOR pathway. Approaches targeting DDIT4-AS1 and its pathway may be an effective strategy for the treatment of chemoresistance in PDAC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12943-022-01647-0.

MicroRNA-640 Inhibition Enhances the Chemosensitivity of Human Glioblastoma Cells to Temozolomide by Targeting Bcl2 Modifying Factor

Glioblastoma (GBM) is the most malignant and challenging type of astrocytoma and also notoriously acknowledged as the most common primary brain tumor globally. Currently, chemotherapy is the most master therapy for tumor and is essential in clinical treatment for GBM. Nevertheless, the characterization of chemotherapy resistance seriously hinders clinical chemotherapy treatment. Accordingly, there are imperious demands for the exploitation of novel chemosensitizer to promote the efficacy of chemotherapy. Our current study was conducted to probe into the potential impacts of microRNA (miR)-640 on the chemosensitivity in GBM and the associated underlying mechanism. Initially, TargetScan software was utilized to predict the targeted genes of miR-640, and the target relationship between miR-640 and Bcl-2-modifying factor (BMF) was validated by double luciferase report assay. Additionally, to explore the role of miR-640/BMF in U251 cells, miR-640 inhibitor/BMF-siRNA was used. U251 cells were processed with 100 μM temozolomide (TMZ) and detected with CCK-8 kit. Eventually, RT-qPCR and Western blotting were used for evaluating Bcl-2, Bax mRNA, and protein expression level. Flow cytometry analysis was performed to measure cellular apoptosis. Initially, the results indicated that BMF was the target gene of miR-640. MiR-640 negatively regulated BMF expression in GBM cells. Besides, the findings revealed that miR-640 inhibition significantly inhibited U251 cell proliferation, promoted cell apoptosis, and increased the sensitivity of GBM cells to TMZ by targeting BMF. Moreover, BMF overexpression significantly suppressed U251 cell proliferation, induced cell apoptosis, and increased the sensitivity of GBM cells to TMZ. Inhibition of miR-640 expression enhances chemosensitivity of human GBM cells to TMZ by targeting BMF.

Alpha7 nicotinic acetylcholine receptor expression in Sorafenib-resistant Hepatocellular carcinoma cells

Hepatocellular carcinoma (HCC), the most prevalent kind of liver cancer, remains one of the world's main causes of death. The alpha7 nicotinic acetylcholine receptor (α7nAchR) has been recognized to be overexpressed in malignancies and chemoresistance. Since little is known about the role of α7nAchR expression in drug-resistant cells, this study was designed to investigate the effect of α7nAchR suppression in combination with Sorafenib (SOR) on SOR-resistant HCC cells. First, SOR-resistant HCC cells were generated. To suppress the expression of α7nAchR, cells were treated with SOR following siRNA transfection. qRT-PCR was used to examine the expression of α7nAchR and apoptotic genes by evaluating the IC50 of SOR and the combination of α7nAchR siRNA and SOR on the survival of resistant cells. Moreover, apoptosis, autophagy, and cell cycle analysis for resistant HCC cells were performed using flow cytometry. Cell migration and colony formation assays were also used for further confirmation. Our results suggest that inhibiting α7nAchR can lead resistant HCC cells to become sensitive. Furthermore, when siRNA and SOR were treated together, HCC-resistant cells showed a considerable reduction in α7nAchR mRNA gene expression. In addition, when α7nAchR was downregulated in combination with SOR, migration and colony formation were inhibited. Apoptosis was triggered by modulating the expression of apoptotic target genes, and cell cycle arrest was observed in the G2-M and subG1 phases. Overexpression of α7nAchR in SOR-resistant HCC cells suggests that it might be a therapeutic target for HCC cell resistance therapy.

Exosomes from bone marrow mesenchymal stem cells decrease chemosensitivity of acute myeloid leukemia cells via delivering miR-10a

Bone marrow mesenchymal stem cells (BMSCs) are an integral part of the acute myeloid leukemia (AML) bone marrow microenvironment and contribute to AML progression. In this study, we explored the communication between BMSCs and AML cells via exosomes. The AML cells co-cultured with BMSCs-Exos were found to have lower chemosensitivity exposed to cytarabine, suggesting that BMSCs-Exos could protect AML cells from cytarabine. Interestingly, miR-10a was elevated in BMSCs-Exos derived from AML (AML-BMSCs-Exos) compared with that from healthy donor. The expression levels of miR-10a in AML cells was significantly up-regulated after co-culture with BMSCs-Exos. Furthermore, the up-regulated miR-10a was an crucial factor contributing to the chemoresistance of leukemia cells. Down-regulation of miR-10a substantially increase chemosensitivity of AML cells treated with BMSCs-Exos. Chemosensitivity of AML cells was also decreased through down-regulating RPRD1A by miR-10a that ultimately lead to the stimulation of the Wnt/β-catenin signaling pathway. Collectively, our findings demonstrated that AML-BMSCs could deliver miR-10a to AML cells via exosomes, which could target RPRD1A and activate Wnt/β-catenin signaling pathway that subsequently decreased chemosensitivity of AML cells.

Lipocalin 2 may be a key factor regulating the chemosensitivity of pancreatic cancer to gemcitabine

Owing to the high heterogeneity of pancreatic cancer, patient-derived xenografts (PDX) can compensate for the defects of cell line-derived xenografts (CDX) and also better preserve the heterogeneity and tumor microenvironment of primary tumors. Further, gemcitabine, which is used for the treatment of various cancers, is prone to tumor drug resistance, and this limits its sustained efficacy. Therefore, in this study, our objective was to screen appropriate individual therapeutic drugs for pancreatic cancer. To this end, we established pancreatic cancer PDX models from different patients and screened gemcitabine sensitivity regulatory molecules via high-throughput transcriptome sequencing and bioinformatics analysis. Based on the results obtained, gemcitabine was identified as the most suitable chemotherapeutic drug in a variety of PDX models. Additionally, our results indicated that Lipocalin 2 (LCN 2) may play an important role in the sensitivity of pancreatic cancer to gemcitabine treatment. Thus, the study provides a new potential intervention target for the treatment of pancreatic cancer in clinical practice.

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PDX model plays an important role in the screening of chemotherapeutic agents for pancreatic cancer.

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Gemcitabine is the most suitable chemotherapeutic drug in a variety of PDX models of pancreatic cancer.

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Lcn2 may be involved in the sensitivity of gemcitabine in the treatment of pancreatic cancer and the change of Lipocalin 2 levels determines the gemcitabine therapeutic output.

Neutrophil extracellular traps (NETs) reduce the diffusion of doxorubicin which may attenuate its ability to induce apoptosis of ovarian cancer cells

Purpose

Although neutrophil extracellular traps (NETs) are present in various tumors, their roles in tumor biology have not been clarified yet. In this study, we examined how NETs affect the pharmacokinetics and effects of doxorubicin (DOX).

Methods

NETs were generated by neutrophils stimulated with phorbol 12-myristate 13-acetate (PMA) or lipopolysaccharide (LPS). DOX was added to NETs and their distribution was observed under fluorescein microscopy, and the diffusion of DOX through 3 μM pores from lower to upper chambers was evaluated with a fluorescence-based assay. Ovarian cancer cells, KOC-2S and SKOV3, were embedded in collagen gel droplets and cultured in 3D way and their apoptosis was examined with flow cytometry.

Results

DOX was mostly co-localized with NETs. The transfer of DOX to upper chambers increased over time, which was significantly decreased by the presence of neutrophils stimulated with PMA or LPS in the lower chamber. DOX outside of the gel increased the rates of annexin V (+) apoptotic cells, which were significantly reduced by the addition of LPS-stimulated neutrophils in media both in KOC-2S and SKOV3. The reduced diffusion and apoptosis were mostly restored by the destruction of the NETs structure with 1000 u/ml DNAse I.

Conclusion

NETs efficiently trap and inhibit the diffusion of DOX which may attenuate its ability to induce apoptosis of ovarian cancer cells. Degradation of NETs with DNAse I may augment the response of ovarian cancer to DOX.

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Doxorubicin is efficiently trapped by neutrophil extracellular traps (NETs).

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NETs suppress diffusion of doxorubicin through micro-pores and infiltration into resected tumor.

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NETs suppress doxorubicin-induced apoptosis of tumor cells in 3-D culture.

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DNAse may augment the effect of anti-cancer drugs by modulating pharmacokinetics.