Two-polarized roles of transcription factor FOSB in lung cancer progression and prognosis: dependent on p53 status.

BACKGROUND: Activator protein-1 (AP-1) represents a transcription factor family that has garnered growing attention for its extensive involvement in tumor biology. However, the roles of the AP-1 family in the evolution of lung cancer remain poorly characterized. FBJ Murine Osteosarcoma Viral Oncogene Homolog B (FOSB), a classic AP-1 family member, was previously reported to play bewilderingly two-polarized roles in non-small cell lung cancer (NSCLC) as an enigmatic double-edged sword, for which the reasons and significance warrant further elucidation. METHODS AND RESULTS: Based on the bioinformatics analysis of a large NSCLC cohort from the TCGA database, our current work found the well-known tumor suppressor gene TP53 served as a key code to decipher the two sides of FOSB - its expression indicated a positive prognosis in NSCLC patients harboring wild-type TP53 while a negative one in those harboring mutant TP53. By constructing a panel of syngeneically derived NSCLC cells expressing p53 in different statuses, the radically opposite prognostic effects of FOSB expression in NSCLC population were validated, with the TP53-R248Q mutation site emerging as particularly meaningful. Transcriptome sequencing showed that FOSB overexpression elicited diversifying transcriptomic landscapes across NSCLC cells with varying genetic backgrounds of TP53 and, combined with the validation by RT-qPCR, PREX1 (TP53-Null), IGFBP5 (TP53-WT), AKR1C3, and ALDH3A1 (TP53-R248Q) were respectively identified as p53-dependent transcriptional targets of FOSB. Subsequently, the heterogenous impacts of FOSB on the tumor biology in NSCLC cells via the above selective transcriptional targets were confirmed in vitro and in vivo. Mechanistic investigations revealed that wild-type or mutant p53 might guide FOSB to recognize and bind to distinct promoter sequences via protein-protein interactions to transcriptionally activate specific target genes, thereby creating disparate influences on the progression and prognosis in NSCLC. CONCLUSIONS: FOSB expression holds promise as a novel prognostic biomarker for NSCLC in combination with a given genetic background of TP53, and the unique interactions between FOSB and p53 may serve as underlying intervention targets for NSCLC.

ABT­737 increases cisplatin sensitivity through the ROS­ASK1­JNK MAPK signaling axis in human ovarian cancer cisplatin­resistant A2780/DDP cells.

Ovarian cancer is a gynecological malignant tumor with the highest mortality rate, and chemotherapy resistance seriously affects patient therapeutic outcomes. It has been shown that the high expression of anti­apoptotic proteins Bcl­2 and Bcl­xL is closely related to ovarian cancer chemotherapy resistance. Therefore, reducing Bcl­2 and Bcl­xL expression levels may be essential for reversing drug resistance in ovarian cancer. ABT­737 is a BH3­only protein mimetic, which can effectively inhibit the expression of the anti­apoptotic proteins Bcl­xL and Bcl­2. Although it has been shown that ABT­737 can increase the sensitivity of ovarian cancer cells to cisplatin, the specific molecular mechanism remains unclear and requires further investigation. In the present study, the results revealed that ABT­737 can significantly increase the activation levels of JNK and ASK1 induced by cisplatin in A2780/DDP cells, which are cisplatin­resistant ovarian cancer cells. Inhibition of the JNK and ASK1 pathway could significantly reduce cisplatin cytotoxicity increased by ABT­737 in A2780/DDP cells, while inhibiting the ASK1 pathway could reduce JNK activation. In addition, it was further determined that ABT­737 could increase reactive oxygen species (ROS) levels in A2780/DDP cells induced by cisplatin. Furthermore, the inhibition of ROS could significantly reduce JNK and ASK1 activation and ABT­737­mediated increased cisplatin cytotoxicity in A2780/DDP cells. Overall, the current data identified that activation of the ROS­ASK1­JNK signaling axis plays an essential role in the ability of ABT­737 to increase cisplatin sensitivity in A2780/DDP cells. Therefore, upregulation the ROS­ASK1­JNK signaling axis is a potentially novel molecular mechanism by which ABT­737 can enhance cisplatin sensitivity of ovarian cancer cells. In addition, the present research can also provide new therapeutic strategies and new therapeutic targets for patients with cisplatin­resistant ovarian cancer with high Bcl­2/Bcl­xL expression patterns.

SIAH2 is specifically expressed during cervical carcinogenesis, and closely relates to the abnormal proliferation of cervical epithelial cells.

Background: Cervical cancer is one of the most common malignancies in women worldwide. As a RING type ubiquitin ligase, SIAH2 has been reported to promote the progression of a variety of tumors by interacting with and targeting multiple chaperones and substrates. The aim of this study was to further identify the role and the related molecular mechanisms involved of SIAH2 in cervical carcinogenesis. Methods and results: Cellular assays in vitro showed that knockdown of SIAH2 inhibited the proliferation, migration and invasion of human cervical cancer cells C33A and SiHa, induced apoptosis, and increased the sensitivity to cisplatin treatment. Knockdown of SIAH2 also inhibited the epithelial-mesenchymal transition and activation of the Akt/mTOR signaling pathway in cervical cancer cells, which were detected by Western blot. Mechanistically, SIAH2, as a ubiquitin ligase, induced the ubiquitination degradation of GSK3ß degradation by using coIP. The results of complementation experiments further demonstrated that GSK3ß overexpression rescued the increase of cell proliferation and invasion caused by SIAH2 overexpression. Specific expression of SIAH2 appeared in precancerous and cervical cancer tissues compared to inflammatory cervical lesions tissues using immunohistochemical staining. The more SIAH2 was expressed as the degree of cancer progressed. SIAH2 was significantly highly expressed in cervical cancer tissues (44/55, 80 %) compared with precancerous tissues (18/69, 26.1 %). Moreover, the expression level of SIAH2 in cervical cancer tissues was significantly correlated with the degree of cancer differentiation, and cervical cancer tissues with higher SIAH2 expression levels were less differentiated. Conclusion: Targeting SIAH2 may be beneficial to the treatment of cervical cancer.

ATP6V1B1 regulates ovarian cancer progression and cisplatin sensitivity through the mTOR/autophagy pathway.

Early detection and effective chemotherapy for ovarian cancer, a serious gynecological malignancy, require further progress. This study aimed to investigate the molecular mechanism of ATPase H+-Transporting V1 Subunit B1 (ATP6V1B1) in ovarian cancer development and chemoresistance. Our data show that ATP6V1B1 is upregulated in ovarian cancer and correlated with decreased progression-free survival. Gain- and loss-of-function experiments demonstrated that ATP6V1B1 promotes the proliferation, migration, and invasion of ovarian cancer cells in vitro, while ATP6V1B1 knockout inhibits tumor growth in vivo. In addition, knocking down ATP6V1B1 increases the sensitivity of ovarian cancer cells to cisplatin. Mechanistic studies showed that ATP6V1B1 regulates the activation of the mTOR/autophagy pathway. Overall, our study confirmed the oncogenic role of ATP6V1B1 in ovarian cancer and revealed that ATP6V1B1 promotes ovarian cancer progression via the mTOR/autophagy axis.

Hypoxia-induced SENP3 promotes chemosensitivity and mitochondrial fission via deSUMOylation of Drp1.

OBJECTIVE: The study aimed to investigate the effect of the SUMOylation status of Drp1 on mitochondrial fission in CDDP-treated HNSCC cells cultured under hypoxic conditions. MATERIALS AND METHODS: The effect of hypoxia on the chemosensitivity of HNCC cells was evaluated by flow cytometry and CCK-8 assays. The biological function of SUMO-specific peptidase 3 (SENP3) was evaluated by loss-of-function assays both in vitro and in vivo. SENP3-regulated deSUMOylation of Drp1 were performed with co-IP assays. RESULTS: SENP3 expression correlated with chemosensitivity in clinical HNSCC samples subjected to hypoxic conditions. Hypoxia-induced ROS increased HIF-1α/SENP3 expression and mitochondrial fission in CDDP-treated HNSCC cells, and these effects were reversed by NAC treatment. SENP3 knockdown reversed hypoxia-induced mitochondrial fission and inhibited HNSCC cell apoptosis, which decreased CDDP sensitivity. Furthermore, hypoxia-induced SENP3 deconjugated SUMO2 from Drp1. CONCLUSION: Our findings revealed that hypoxia-induced SENP3 facilitates CDDP sensitivity and mitochondrial fission via deSUMOylation of Drp1.

Targeting the KAT8/YEATS4 Axis Represses Tumor Growth and Increases Cisplatin Sensitivity in Bladder Cancer.

Bladder cancer (BC) is one of the most common tumors characterized by a high rate of relapse and a lack of targeted therapy. Here, YEATS domain-containing protein 4 (YEATS4) is an essential gene for BC cell viability using CRISPR-Cas9 library screening is reported, and that HUWE1 is an E3 ligase responsible for YEATS4 ubiquitination and proteasomal degradation by the Protein Stability Regulators Screening Assay. KAT8-mediated acetylation of YEATS4 impaired its interaction with HUWE1 and consequently prevented its ubiquitination and degradation. The protein levels of YEATS4 and KAT8 are positively correlated and high levels of these two proteins are associated with poor overall survival in BC patients. Importantly, suppression of YEATS4 acetylation with the KAT8 inhibitor MG149 decreased YEATS4 acetylation, reduced cell viability, and sensitized BC cells to cisplatin treatment. The findings reveal a critical role of the KAT8/YEATS4 axis in both tumor growth and cisplatin sensitivity in BC cells, potentially generating a novel therapeutic strategy for BC patients.

LINC00460 knockdown sensitizes cervical cancer to cisplatin by downregulating TGFBI.

The acquired resistance of cancer to cisplatin (DDP) limits the efficacy of chemotherapy. The prognostic value of long noncoding RNA (lncRNA) LINC00460 has been reported in cervical cancer. However, its effect on DDP sensitivity in cervical cancer remains poorly understood. In present study, LINC00460 was screened out through bioinformatics analysis. The expression levels of mRNAs and proteins were measured by reverse transcription-quantitative PCR (RT-qPCR) or western blot analysis. The sensitivity to DDP was investigated using an CCK8 assay. Cell apoptosis was determined by flow cytometry. The differentially expressed genes that were associated with the poor prognosis of cervical cancer were screened, and their correlations with LINC00460 expression were explored using Pearson's correlation analysis. Tumor xenograft model was used to assess the effect of LINC00460 knockdown on DDP sensitivity in vivo. The interaction between miR-338-3p and LINC00460 or transforming growth factor ß-induced protein (TGFBI) was confirmed by RNA immunoprecipitation (RIP) and luciferase reporter assays. LINC00460 expression was increased in cervical cancer tissues and cells. High expression of LINC00460 was associated with dismal prognosis in cervical cancer patients. Silencing of LINC00460 increased drug sensitivity and induced apoptosis in DDP-resistant-cervical cancer cells. LINC00460 knockdown enhanced DDP sensitivity in cervical cancer cells largely by downregulating TGFBI expression. LINC00460 knockdown enhanced the sensitivity of cervical cancer to DDP in vivo, and this effect was partly mediated by the downregulation of TGFBI. LINC00460 positively regulated TGFBI expression, possibly by acting as a sponge of miR-338-3p. LINC00460 knockdown contributed to DDP sensitivity of cervical cancer by downregulating TGFBI, providing a novel mechanism underlying the acquisition of DDP sensitivity.

Endolysosomal two-pore channel 2 plays opposing roles in primary and metastatic malignant melanoma cells.

The ion channel two-pore channel 2 (TPC2), localised on the membranes of acidic organelles such as endo-lysosomes and melanosomes, has been shown to play a role in pathologies including cancer, and it is differently expressed in primary versus metastatic melanoma cells. Whether TPC2 plays a pro- or anti-oncogenic role in different tumour conditions is a relevant open question which we have explored in melanoma at different stages of tumour progression. The behaviour of primary melanoma cell line B16F0 and its metastatic subline B16F10 were compared in response to TPC2 modulation by silencing (by small interfering RNA), knock-out (by CRISPR/Cas9) and overexpression (by mCherry-TPC2 transfected plasmid). TPC2 silencing increased cell migration, epithelial-to-mesenchymal transition and autophagy in the metastatic samples, but abated them in the silenced primary ones. Interestingly, while TPC2 inactivation failed to affect markers of proliferation in both samples, it strongly enhanced the migratory behaviour of the metastatic cells, again suggesting that in the more aggressive phenotype TPC2 plays a specific antimetastatic role. In line with this, overexpression of TPC2 in B16F10 cells resulted in phenotype rescue, that is, a decrease in migratory ability, thus collectively resuming traits of the B16F0 primary cell line. Our research shows a novel role of TPC2 in melanoma cells that is intriguingly different in initial versus late stages of cancer progression.

LASS2 enhances chemosensitivity to cisplatin by inhibiting PP2A-mediated ß-catenin dephosphorylation in a subset of stem-like bladder cancer cells.

BACKGROUND: The benefits of first-line, cisplatin-based chemotherapy for muscle-invasive bladder cancer are limited due to intrinsic or acquired resistance to cisplatin. Increasing evidence has revealed the implication of cancer stem cells in the development of chemoresistance. However, the underlying molecular mechanisms remain to be elucidated. This study investigates the role of LASS2, a ceramide synthase, in regulating Wnt/ß-catenin signaling in a subset of stem-like bladder cancer cells and explores strategies to sensitize bladder cancer to cisplatin treatment. METHODS: Data from cohorts of our center and published datasets were used to evaluate the clinical characteristics of LASS2. Flow cytometry was used to sort and analyze bladder cancer stem cells (BCSCs). Tumor sphere formation, soft agar colony formation assay, EdU assay, apoptosis analysis, cell viability, and cisplatin sensitivity assay were used to investigate the functional roles of LASS2. Immunofluorescence, immunoblotting, coimmunoprecipitation, LC-MS, PCR array, luciferase reporter assays, pathway reporter array, chromatin immunoprecipitation, gain-of-function, and loss-of-function approaches were used to investigate the underlying mechanisms. Cell- and patient-derived xenograft models were used to investigate the effect of LASS2 overexpression and a combination of XAV939 on cisplatin sensitization and tumor growth. RESULTS: Patients with low expression of LASS2 have a poorer response to cisplatin-based chemotherapy. Loss of LASS2 confers a stem-like phenotype and contributes to cisplatin resistance. Overexpression of LASS2 results in inhibition of self-renewal ability of BCSCs and increased their sensitivity to cisplatin. Mechanistically, LASS2 inhibits PP2A activity and dissociates PP2A from ß-catenin, preventing the dephosphorylation of ß-catenin and leading to the accumulation of cytosolic phospho-ß-catenin, which decreases the transcription of the downstream genes ABCC2 and CD44 in BCSCs. Overexpression of LASS2 combined with a tankyrase inhibitor (XAV939) synergistically inhibits tumor growth and restores cisplatin sensitivity. CONCLUSIONS: Targeting the LASS2 and ß-catenin pathways may be an effective strategy to overcome cisplatin resistance and inhibit tumor growth in bladder cancer patients.

ANKRD2 expression combined with TNFRSF19 expression for evaluating the prognosis of oral squamous cell carcinoma patients.

Objective: As an important chemotherapy drug, cisplatin has been widely used in the treatment of many cancers. However, many patients, including oral squamous cell carcinoma (OSCC) patients, experience unacceptable outcomes from cisplatin treatment. Thus, we devised a risk model for predicting the sensitivity of OSCC patients to cisplatin treatment, to provide a reference for clinical practice. Methods: CAL-27 and SCC-9 cell lines treated or not with cisplatin and data from The Cancer Genome Atlas (TCGA) were screened for simultaneously and significantly differentially expressed genes. Next, we built a risk model for predicting cisplatin sensitivity in OSCC patients. Reverse transcription-polymerase chain reaction (RT-PCR), pathological samples and clinical data were used to examine the reliability of the model. Results: ANKRD2 and TNFRSF19 were differentially expressed between the OSCC metastasis cell line HSC-3 treated and not treated with cisplatin, as well as between the OSCC cell line SCC-25 and the cell line SCC25-DDP, which has cisplatin chemoresistance. We found that the expression of ANKRD2 and TNFRSF19 had a significant influence on the prognosis of OSCC patients. The risk model that combined ANKRD2 and TNFRSF19 to predict sensitivity to cisplatin in OSCC patients was confirmed by analysing the pathological samples and follow-up information of clinical patients. Conclusions: The expression of ANKRD2 and TNFRSF19 is associated with cisplatin sensitivity and prognosis in patients with OSCC. The survival outcome of patients with oral squamous cell carcinoma (OSCC) was found to be significantly worse in those with high expression of ANKRD2 combined with low expression of TNFRSF19. ANKRD2 and TNFRSF19 may be targets for cisplatin sensitivity prediction in OSCC patients. These findings may provide novel strategies for overcoming cisplatin resistance.

Knockdown of PRMT1 suppresses the malignant biological behavior of osteosarcoma cells and increases cisplatin sensitivity via c-Myc-mediated BCAT1 downregulation.

Increasing evidence indicated that protein arginine methyltransferase-1 (PRMT1) is an oncogene in multiple malignant tumors, including osteosarcoma (OS). The aim of this study was to investigate the underlying mechanism of PRMT1 in OS. The effects of PRMT1 or BCAT1, branched-chain amino acid transaminase 1 (BCAT1) on OS cell proliferation, invasion, autophagy, and apoptosis in vitro were examined. Moreover, molecular control of PRMT1 on c-Myc or transactivation of BCAT1 on c-Myc was assessed by chromatin immunoprecipitation and quantitative reverse transcription PCR assays. The effects of PRMT1 in vivo were examined with a xenograft tumor model. The results showed that PRMT1 was potently upregulated in OS tissues and cells. Upregulation of PRMT1 markedly increased OS cell proliferation and invasion in vitro and reduced cell apoptosis, whereas PRMT1 silencing showed the opposite effects. Cisplatin, one of the most effective chemotherapeutic drugs, improved cell survival rate by inducing the expression of PRMT1 to downregulate the cisplatin sensitivity. Meanwhile, the cisplatin-induced upregulation of PRMT1 expression caused dramatically autophagy induction and autophagy-mediated apoptosis by inactivating the mTOR signaling pathway, which could be reversed by 3-methyladenine, an autophagy inhibitor, or PRMT1 silencing. PRMT1 could activate c-Myc transcription and increase c-Myc-mediated expression of BCAT1. Furthermore, BCAT1 overexpression counteracted the effects of PRMT1 knockdown on cell proliferation, invasion, and apoptosis. Of note, deficiency of PRMT1 suppressed tumor growth in vivo. PRMT1 facilitated the proliferation and invasion of OS cells, inhibited cell apoptosis, and decreased chemotherapy sensitivity through c-Myc/BCAT1 axis, which may become potential target in treating OS.

USP43 impairs cisplatin sensitivity in epithelial ovarian cancer through HDAC2-dependent regulation of Wnt/ß-catenin signaling pathway.

Epithelial ovarian cancer (EOC) is the leading cause of cancer death all over the world. USP43 functions as a tumor promoter in various malignant cancers. Nevertheless, the biological roles and mechanisms of USP43 in EOC remain unknown. In this study, USP43 was highly expressed in EOC tissues and cells, and high expression of USP43 were associated with a poor prognosis of EOC. USP43 overexpression promoted EOC cell proliferation, enhanced the ability of migration and invasion, decreased cisplatin sensitivity and inhibited apoptosis. Knockdown of USP43 in vitro effectively retarded above malignant progression of EOC. In vivo xenograft tumors, silencing USP43 slowed tumor growth and enhanced cisplatin sensitivity. Mechanistically, USP43 inhibited HDAC2 degradation and enhanced HDAC2 protein stability through its deubiquitylation function. USP43 diminished the sensitivity of EOC cells to cisplatin through activation of the Wnt/ß-catenin signaling pathway mediated by HDAC2. Taken together, the data in this study revealed the functions of USP43 in proliferation, migration, invasion, chemoresistance of EOC cells, and the mechanism of HDAC2-mediated Wnt/ß-catenin signaling pathway. Thus, USP43 might serve as a potential target for the control of ovarian cancer progression.

Downregulation of BUBR1 regulates the proliferation and cell cycle of breast cancer cells and increases the sensitivity of cells to cisplatin.

Breast cancer (BC) is a significant tissue for women's health worldwide. The spindle assembly checkpoint protein family includes BUBR1 (Bub1-related kinase or MAD3/Bub1b). High expression of BUBR1 promotes cell cycle disorders, leading to cell carcinogenesis and cancer progression. However, the underlying molecular mechanism and the role of BUBR1 in BC progression are unclear. The published dataset was analyzed to evaluate the clinical relevance of BUBR1. BUBR1 was knocked down in BC cells using shRNA. The CCK-8 assay was used to measure the cell viability, and mRNA and protein expression levels were detected by RT-qPCR and Western blot (WB). Cell apoptosis and cell cycle were detected by flow cytometry. Subcutaneous xenograft model was used to assess in vivo tumor growth. BUBR1 was found to be highly expressed in BC. The high expression of BUBR1 was associated with poor prognosis of BC patients. Upon BUBR1 knockdown using shRNA, the proliferation and metastatic ability of cells were decreased. Moreover, the cells with BUBR1 knockdown underwent cell cycle arrest. And the results showed that BUBR1 loss inhibited the phosphorylation of TAK1/JNK. In vitro and in vivo studies indicated the knockdown of BUBR1 rendered the BC cells more sensitive to cisplatin. In summary, BUBR1 may be a potential therapeutic target for BC and targeting BUBR1 may help overcome cisplatin resistance in BC patients.

MicroRNA-367-3p directly targets RAB23 and inhibits proliferation, migration and invasion of bladder cancer cells and increases cisplatin sensitivity.

OBJECTIVES: This study investigated the biological role of miR-367-3p upregulation in bladder cancer and verified the mutual relation between miR-367-3p and RAB23. MATERIALS AND METHODS: Expression levels of miR-367-3p were determined by RT-qPCR in bladder cancer cell lines and human bladder cancer tissues. The effects of miR-367-3p on proliferation, migration and invasion were evaluated by cell colony formation assays, wound healing assays and trans-well assays, respectively. The effects of miR-367-3p and RAB23 on cisplatin sensitivity of bladder cancer cells were assessed by CCK-8 assay. The expression of its target-RAB23 was determined by western blotting in T24, 5637. Plasmids used in dual-luciferase assays were constructed to confirm the action of miR-367-3p on downstream target-RAB23 in T24 cells. And also, the role of miR-367-3p in tumorigenesis was also confirmed in nude mouse models. RESULTS: The downregulation of miR-367-3p was observed in human bladder cancer tissues. MiR-367-3p downregulation positively correlated with tumor stage and tumor grade. MiR-367-3p overexpression in T24, 5637 cells suppressed the proliferation, migration, and invasion of bladder cancer cells in vitro while decreasing IC50 values under T24 and 5637 cisplatin treatment conditions. RAB23 was shown to be upregulated in bladder cancer tissues and cell lines. MiR-367-3p directly bound to the 3' UTR of RAB23 in T24 cells. RAB23 was potentially accounted for the aforementioned functions of miR-367-3p. Tumor formation experiments in nude mouse models confirmed that overexpression of miR-367-3p could inhibit tumor growth and invasion in vivo. CONCLUSIONS: miR-367-3p acts as a tumor suppressor in bladder cancer by downregulating RAB23 signaling. We conjecture that miR-367-3p-mediated downregulation of RAB23 expression may be a new therapeutic strategy for bladder cancer treatment.

Circular RNA from Tyrosylprotein Sulfotransferase 2 Gene Inhibits Cisplatin Sensitivity in Head and Neck Squamous Cell Carcinoma by Sponging miR-770-5p and Interacting with Nucleolin.

Chemoresistance poses a significant challenge in the treatment of advanced head and neck squamous cell cancer (HNSCC). The role and mechanism of circular RNAs (circRNAs) in HNSCC chemoresistance remain understudied. We conducted circRNA microarray analysis to identify differentially expressed circRNAs in HNSCC. The expression of circRNAs from the tyrosylprotein sulfotransferase 2 (TPST2) gene and miRNAs was evaluated through qPCR, while the circular structure of circTPST2 was verified using Sanger sequencing and RNase R. Through Western blotting, biotin-labeled RNA pulldown, RNA immunoprecipitation, mass spectrometry, and rescue experiments, we discovered miR-770-5p and nucleolin as downstream targets of circTPST2. Functional tests, including CCK8 assays and flow cytometry, assessed the chemoresistance ability of circTPST2, miR-770-5p, and Nucleolin. Additionally, FISH assays determined the subcellular localization of circTPST2, miR-770-5p, and Nucleolin. IHC staining was employed to detect circTPST2 and Nucleolin expression in HNSCC patients. circTPST2 expression was inversely correlated with cisplatin sensitivity in HNSCC cell lines. Remarkably, high circTPST2 expression correlated with lower overall survival rates in chemotherapeutic HNSCC patients. Mechanistically, circTPST2 reduced chemosensitivity through sponge-like adsorption of miR-770-5p and upregulation of the downstream protein Nucleolin in HNSCC cells. The TCGA database revealed improved prognosis for patients with low circTPST2 expression after chemotherapy. Moreover, analysis of HNSCC cohorts demonstrated better prognosis for patients with low Nucleolin protein expression after chemotherapy. We unveil circTPST2 as a circRNA associated with chemoresistance in HNSCC, suggesting its potential as a marker for selecting chemotherapy regimens in HNSCC patients. Further exploration of the downstream targets of circTPST2 advanced our understanding and improved treatment strategies for HNSCC.

Metabolic reprogramming induced by DCA enhances cisplatin sensitivity through increasing mitochondrial oxidative stress in cholangiocarcinoma.

Background: Cholangiocarcinoma has obvious primary multidrug resistance and is generally resistant to cisplatin and other chemotherapy drugs and high glycolytic levels may be associated with chemotherapy resistance of cholangiocarcinoma cells. Dichloroacetate (DCA) is a specific inhibitor of PDK, which can promote mitochondrial aerobic oxidation process by activating PDH. In the past few years, there have been an increasing number of studies supporting the action of DCA against cancer, which also provided evidence for targeting metabolism to enhance the efficacy of cholangiocarcinoma chemotherapy. Methods: Glucose uptake and lactic acid secretion were used to detect cell metabolism level. Cell apoptosis and cell cycle were detected to confirm cell fate induced by cisplatin combined with DCA. Mito-TEMPO was used to inhibit mtROS to explore the relationship between oxidative stress and cell cycle arrest induced by DCA under cisplatin stress. Finally, PCR array and autophagy inhibitor CQ were used to explore the potential protective mechanism under cell stress. Results: DCA changed the metabolic model from glycolysis to aerobic oxidation in cholangiocarcinoma cells under cisplatin stress. This metabolic reprogramming increased mitochondrial reactive oxygen species (mtROS) levels, which promoted cell cycle arrest, increased the expression of antioxidant genes and activated autophagy. Inhibition of autophagy further increased the synergistic effect of DCA and cisplatin. Conclusion: DCA increased cisplatin sensitivity in cholangiocarcinoma cells via increasing the mitochondria oxidative stress and cell growth inhibition. Synergistic effects of DCA and CQ were observed in cholangiocarcinoma cells, which further increased the cisplatin sensitivity via both metabolic reprogramming and inhibition of the stress response autophagy.

AMIGO2 attenuates innate cisplatin sensitivity by suppression of GSDME-conferred pyroptosis in non-small cell lung cancer.

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer. Cisplatin is commonly used in the treatment of many malignant tumours including NSCLC. The innate drug sensitivity greatly affects the clinical efficacy of cisplatin-based chemotherapy. As a plasma membrane adhesion molecule, amphoterin-induced gene and ORF-2 (AMIGO2) initially identified as a neurite outgrowth factor has been recently found to play a crucial role in cancer occurrence and progression. However, it is still unclear whether AMIGO2 is involved in innate cisplatin sensitivity. In the present study, we provided the in vitro and in vivo evidences indicating that the alteration of AMIGO2 expression triggered changes of innate cisplatin sensitivity as well as cisplatin-induced pyroptosis in NSCLC. Further results revealed that AMIGO2 might inhibit cisplatin-induced activation of (caspase-8 and caspase-9)/caspase-3 via stimulating PDK1/Akt (T308) signalling axis, resulting in suppression of GSDME cleavage and the subsequent cell pyroptosis, thereby decreasing the sensitivity of NSCLC cells to cisplatin treatment. The results provided a new insight that AMIGO2 regulated the innate cisplatin sensitivity of NSCLC through GSDME-mediated pyroptosis.

SETD8, a frequently mutated gene in cervical cancer, enhances cisplatin sensitivity by impairing DNA repair.

BACKGROUND: Cisplatin is commonly used to treat cervical cancer while drug resistance limits its effectiveness. There is an urgent need to identify strategies that increase cisplatin sensitivity and improve the outcomes of chemotherapy. RESULTS: We performed whole exome sequencing (WES) of 156 cervical cancer tissues to assess genomic features related to platinum-based chemoresistance. By using WES, we identified a frequently mutated locus SETD8 (7%), which was associated with drug sensitivity. Cell functional assays, in vivo xenografts tumor growth experiments, and survival analysis were used to investigate the functional significance and mechanism of chemosensitization after SETD8 downregulation. Knockdown of SETD8 increased the responsiveness of cervical cancer cells to cisplatin treatment. The mechanism is exerted by reduced binding of 53BP1 to DNA breaks and inhibition of the non-homologous end joining (NHEJ) repair pathway. In addition, SETD8 expression was positively correlated with resistance to cisplatin and negatively associated with the prognosis of cervical cancer patients. Further, UNC0379 as a small molecule inhibitor of SETD8 was found to enhance cisplatin sensitivity both in vitro and in vivo. CONCLUSIONS: SETD8 was a promising therapeutic target to ameliorate cisplatin resistance and improve the efficacy of chemotherapy.

Long non-coding RNA DSCAS regulates cisplatin sensitivity in lung squamous cell carcinoma by competitively binding to miR-646-3p.

Background: Platinum-based chemotherapy is the main treatment for advanced lung squamous cell carcinoma (LUSC). Eventually, patients with LUSC develop resistance to cisplatin, which affects the prognosis. Hence, the researchers sought to find a lncRNA in LUSC that affects resistance to cisplatin. Methods: The lncRNA microarray assay was used to screen the differential expression of lncRNA. qPCR was used to detect lncRNA DSCAS (DSCAS) expression in tissues and cell lines. Lentiviral transfection was used to regulate the expression of DSCAS. CCK-8, colony formation, wound healing, transwell, and flow cytometry assays were used to assess the biological behaviors and sensitivity to cisplatin of LUSC cell. RNA-RNA interaction was tested using the dual luciferase reporting assay, RNA-IP, and RNA-RNA pull-down assay. The downstream pathway of DSCAS was verified by qPCR and Western blotting assays. Results: DSCAS was highly expressed in LUSC tissues and cells, and its expression levels were higher in cisplatin-insensitive tissues than in cisplatin-sensitive tissues. Elevation of DSCAS promoted cell proliferation, migration and invasion as well as increased cisplatin resistance of lung cancer cells, while demotion of DSCAS inhibited cell proliferation, migration and invasion as well as decreased the cisplatin resistance of lung cancer cells. DSCAS bound to miR-646-3p to regulate the expression of Bcl-2 and Survivin, which affected the cell apoptosis and sensitivity to cisplatin in LUSC cells. Conclusions: DSCAS regulates biological behavior and cisplatin sensitivity in LUSC cells by competitively binding to miR-646-3p to mediate the expression of Survivin and Bcl-2, known as apoptosis-related proteins.

microRNA-660 Enhances Cisplatin Sensitivity via Decreasing SATB2 Expression in Lung Adenocarcinoma.

Increasing evidence suggests that microRNAs' (miRNAs) abnormal expression is one of the main factors of chemotherapy resistance in various cancers. However, the role of miRNAs in lung adenocarcinoma (LUAD) resistance to cisplatin is still unclear. In this study, we analyzed a microarray dataset to investigate miRNAs related to cisplatin resistance in LUAD. The expression of miRNAs in LUAD tissues and cell lines was detected using real-time quantitative polymerase chain reaction (RT-qPCR). Special AT-Rich Sequence-Binding Protein 2 (SATB2) in LUAD cell lines was detected using RT-qPCR and Western blot. Cell proliferation was measured by CCK8 and colony formation assays, while cell cycle and apoptosis were measured by flow cytometry. A dual-luciferase reporter assay was performed to confirm that SATB2 is a target gene of microRNA-660 (miR-660). We showed that the expression of miR-660 was not only decreased in LUAD cells and tissues but also further decreased in the cisplatin-resistant A549 cell line. The overexpression of miR-660 increased cisplatin sensitivity in LUAD cells. In addition, we identified SATB2 as a direct target gene of miR-660. We also revealed that miR-660 increased cisplatin sensitivity in LUAD cells via targeting SATB2. In conclusion, miR-660/SATB2 axis is a key regulator of cisplatin resistance in LUAD.