FOXA2 Activates RND1 to Regulate Arachidonic Acid Metabolism Pathway and Suppress Cisplatin Resistance in Lung Squamous Cell Carcinoma.

BACKGROUND: The primary cause of cancer-related fatalities globally is lung cancer. Although the chemotherapy drug cisplatin (DDP) has brought certain benefits to patients, the rapid development of drug resistance has greatly hindered treatment success. METHODS: We used the lung squamous cell carcinoma (LUSC) mRNA data set to explore the differentially expressed gene (RND1) in LUSC and detected RND1 expression in LUSC cells and DDP-resistant cells by qRT-PCR. Meanwhile, we performed abnormal expression treatment on RND1 and conducted CCK8, colony formation, and flow cytometry to evaluate the impact of RND1 expression on cell proliferation, apoptosis, and DDP resistance. In addition, we analyzed metabolism pathways involving RND1 using GSEA. We also used online tools such as hTFtarget and JASPAR to screen for the upstream transcription factor FOXA2 of RND1 and verified their relationship through CHIP and dual luciferase experiments. Finally, we validated the role of FOXA2-RND1 in DDP resistance in LUSC through the above experiments. RESULTS: RND1 was downregulated in LUSC, and overexpression of RND1 repressed proliferation and DDP resistance of LUSC cells and facilitated cell apoptosis. RND1 modulated the arachidonic acid (AA) metabolism pathway, and FOXA2 positively manipulated RND1 expression. By activating FOXA2, stabilizing RND1, and regulating AA levels, the sensitivity of LUSC cells to DDP could be enhanced. CONCLUSION: Our study suggested that FOXA2 positively modulated the RND1-AA pathway, which repressed the resistance of LUSC cells to DDP.

LncRNA SH3PXD2A-AS1 facilitates cisplatin resistance in non-small cell lung cancer by regulating FOXM1 succinylation.

BACKGROUND: Long noncoding RNAs (lncRNAs) play vital regulatory functions in non-small cell lung cancer (NSCLC). Cisplatin (DDP) resistance has significantly decreased the effectiveness of DDP-based chemotherapy in NSCLC patients. This study aimed to investigate the effects of SH3PXD2A antisense RNA 1 (SH3PXD2A-AS1) on DDP resistance in NSCLC. METHODS: Proliferation and apoptosis of DDP-resistant NSCLC cells were detected using cell counting kit-8 and flow cytometry assays. The interaction between SH3PXD2A-AS1 and sirtuin 7 (SIRT7) was assessed using co-immunoprecipitation (Co-IP), RNA pull-down, RNA immunoprecipitation (RIP), RNA fluorescence in situ hybridization, and immunofluorescence assays, while succinylation (SUCC) of Forkhead Box M1 (FOXM1) was analyzed by IP and Western blot assays. The role of SH3PXD2A-AS1 in vivo was explored using a xenografted tumor model. RESULTS: Expression of SH3PXD2A-AS1 was found elevated in DDP-resistant NSCLC cells, while it's knocking down translated into suppression of cell viability and promotion of apoptosis. Moreover, silencing of SH3PXD2A-AS1 resulted in decreased FOXM1 protein level and enhanced FOXM1-SUCC protein level. The SIRT7 was found to interact with FOXM1, translating into inhibition of FOXM1 SUCC at the K259 site in human embryonic kidney (HEK)-293T cells. Overexpressing of SIRT7 reversed the increase of FOXM1-SUCC protein level and apoptosis, and the decrease of cell viability induced by silencing of SH3PXD2A-AS1. In tumor-bearing mice, SH3PXD2A-AS1 inhibition suppressed tumor growth and the protein levels of Ki67, SIRT7, and FOXM1. CONCLUSION: SH3PXD2A-AS1 promoted DDP resistance in NSCLC cells by regulating FOXM1 SUCC via SIRT7, offering a promising therapeutic approach for NSCLC.

Bufalin: A promising therapeutic drug against the cisplatin-resistance of ovarian cancer by targeting the USP36/c-Myc axis.

Cisplatin (DPP) resistance is a severe obstacle to ovarian cancer (OC) treatment. Our research aims to uncover the therapeutic effect and the underlying mechanism of Bufalin against DDP resistance. The cell viability, proliferation capacity, γH2AX expression, and apoptosis ratio were quantified via CCK8 assay, colony formation assay, immunofluorescence, and flow cytometry analysis respectively. Xenografting experiment was performed to detect the tumor growth. Molecular docking was applied to mimic the combination of Bufalin and USP36 protein, and Western blotting was conducted to measure the Bax, Bcl-2, γH2AX, USP36, and c-Myc expression. The c-Myc ubiquitination and half-life were detected via ubiquitination assay and cycloheximide chasing assay. Bufalin treatment notably suppressed the cell viability and colony numbers, and increased the apoptosis ratio and γH2AX level in the DDP treatment group. Bufalin therapy also notably inhibited tumor growth, Bax, Bcl-2, and γH2AX expression in vivo. Moreover, the Bufalin application remarkedly reduced the c-Myc expression and half-life and increased the c-Myc ubiquitination via interaction and subsequent down-regulation of USP36. Knockdown of USP36 reversed the antiproliferative effect and proapoptotic capacity of Bufalin therapy in the DDP treatment group. In conclusion, Bufalin can overcome the DDP resistance in vitro and in vivo via the USP36/c-Myc axis, which innovatively suggests the therapeutic potential of Bufalin against DDP resistance ovarian cancer.

Silencing HEATR1 Rescues Cisplatin Resistance of Non-Small Cell Lung Cancer by Inducing Ferroptosis via the p53/SAT1/ALOX15 Axis.

BACKGROUND: Cisplatin (DDP) is a commonly used chemotherapy agent. However, its resistance to the drug is a major challenge in its clinical application. Earlier research has suggested a connection between HEATR1 and chemoresistance in cancer. However, additional investigation is needed to better understand its involvement in resistance to DDP. In this study, we aimed to determine the regulatory effect of HEATR1 on the resistance of cisplatin in NSCLC. METHODS: We collected specimens of both DDP-resistant and non-resistant NSCLC to examine the expression of HEATR1. Additionally, we established cisplatin-resistant cells of NSCLC using the A549 cell line. Cell ability was examined by CCK-8 assay. Cell apoptosis and lipid ROS were examined by flow cytometry. The expressions of HEATR1, p53, SAT1, and ALOX15 were determined by qRT-PCR and Western blot. The tumor xenograft experiment was conducted to assess the impact of silencing HEATR1 on cisplatin resistance in vivo in NSCLC. RESULTS: The expression levels of HEATR1 were found to be significantly elevated in DDP-resistant tissues and cells of NSCLC as compared to non-resistant counterparts. Conversely, the expression levels of p53, SAT1, and ALOX15 were observed to be reduced in DDP-resistant cells. Through the inhibition of HEATR1, the proliferation of DDP-resistant cells was significantly suppressed, while the generation of lipid ROS was enhanced. This effect was achieved by activating ferroptosis and the p53/SAT1/ALOX15 pathway, as demonstrated both in vitro and in vivo. Conversely, the overexpression of HEATR1 exhibited opposite effects. Furthermore, the silencing of p53 and ALOX15 reversed the oncogenic effects of HEATR1 and inhibited ferroptosis in DDP-resistant NSCLC cells, suggesting the involvement of p53 and ALOX15 in HEATR1-mediated DDP resistance. CONCLUSION: Finally, the findings revealed that HEATR1 silencing reduced DDP resistance in NSCLC by inducing ferroptosis via the p53/SAT1/ALOX15 axis. HEATR1 might become a potential target for overcoming DDP resistance in NSCLC treatment.

Folate-modified liposomes mediate the co-delivery of cisplatin with miR-219a-5p for the targeted treatment of cisplatin-resistant lung cancer.

Cisplatin (DDP) resistance, often leading to first-line chemotherapy failure in non-small cell lung cancer (NSCLC), poses a significant challenge. MiR-219a-5p has been reported to enhance the sensitivity of human NSCLC to DDP. However, free miR-219a-5p is prone to degradation by nucleases in the bloodstream, rendering it unstable. In light of this, our study developed an efficient nanodrug delivery system that achieved targeted delivery of DDP and miR-219a-5p by modifying liposomes with folate (FA). Based on the results of material characterization, we successfully constructed a well-dispersed and uniformly sized (approximately 135.8 nm) Lipo@DDP@miR-219a-5p@FA nanodrug. Agarose gel electrophoresis experiments demonstrated that Lipo@DDP@miR-219a-5p@FA exhibited good stability in serum, effectively protecting miR-219a-5p from degradation. Immunofluorescence and flow cytometry experiments revealed that, due to FA modification, Lipo@DDP@miR-219a-5p@FA could specifically bind to FA receptors on the surface of tumor cells (A549), thus enhancing drug internalization efficiency. Safety evaluations conducted in vitro demonstrated that Lipo@DDP@miR-219a-5p@FA exhibited no significant toxicity to non-cancer cells (BEAS-2B) and displayed excellent blood compatibility. Cellular functional experiments, apoptosis assays, and western blot demonstrated that Lipo@DDP@miR-219a-5p@FA effectively reversed DDP resistance in A549 cells, inhibited cell proliferation and migration, and further promoted apoptosis. In summary, the Lipo@DDP@miR-219a-5p@FA nanodrug, through specific targeting of cancer cells and reducing their resistance to DDP, significantly enhanced the anti-NSCLC effects of DDP in vitro, providing a promising therapeutic option for the clinical treatment of NSCLC.

Role and mechanism of COL3A1 in regulating the growth, metastasis, and drug sensitivity in cisplatin-resistant non-small cell lung cancer cells.

Non-small cell lung cancer (NSCLC) is among the most difficult malignancies to treat. Type III collagen (COL3A1) can affect the progression and chemoresistance development of NSCLC. We herein explored the mechanism that drives COL3A1 dysregulation in NSCLC. Potential RNA-binding proteins (RBPs) and transcription factors (TFs) that could bind to COL3A1 were searched by bioinformatics. mRNA expression was detected by quantitative PCR. Protein expression was evaluated using immunoblotting and immunohistochemistry. The effects of the variables were assessed by gauging cell growth, invasiveness, migratory capacity, apoptosis, and cisplatin (DDP) sensitivity. The direct YY1/COL3A1 relationship was confirmed by ChIP and luciferase reporter experiments. Xenograft experiments were done to examine COL3A1's function in DDP efficacy. COL3A1 showed enhanced expression in DDP-resistant NSCLC. In H460/DDP and A549/DDP cells, downregulation of COL3A1 exerted inhibitory functions in cell growth, invasiveness, and migration, as well as promoting effects on cell DDP sensitivity and apoptosis. Mechanistically, ELAV-like RNA binding protein 1 (ELAVL1) enhanced the mRNA stability and expression of COL3A1, and Yin Yang 1 (YY1) promoted the transcription and expression of COL3A1. Furthermore, upregulation of COL3A1 reversed ELAVL1 inhibition- or YY1 deficiency-mediated functions in DDP-resistant NSCLC cells. Additionally, COL3A1 downregulation enhanced the anti-tumor efficacy of DDP in vivo. Our investigation demonstrates that COL3A1 upregulation, induced by both RBP ELAVL1 and TF YY1, exerts important functions in phenotypes of NSCLC cells with DDP resistance, offering an innovative opportunity in the treatment of drug-resistant NSCLC.

Suppression of ZNF205-AS1/EGR4 positive feedback loop attenuates cisplatin resistance of non-small cell lung cancer cells via targeting miR-138-5p/OCT4 pathway.

Background: Long non-coding RNAs (lncRNAs) are frequently reported to involve in the onset and development of non-small cell lung cancer (NSCLC). Cisplatin (DDP) resistance continues to pose a daunting challenge for improving the prognosis of NSCLC patients. The current study intends to elucidate the molecular mechanisms underlying the function of lncRNA ZNF205 AS1/early growth response 4 (EGR4) positive feedback loop in DDP resistance of NSCLC. Methods: A series of assays, including real-time polymerase chain reaction (PCR), western blotting, flow cytometry, and dual-luciferase reporter, were performed to evaluate the effect of ZNF205-AS1/EGR4 loop in the established DDP-resistant A549 cell line and its progenitor A549 cell line. Immunohistochemistry (IHC) technique was conducted to investigate the expression pattern of EGR4 and octamer-binding protein 4 (OCT4) in NSCLC tissues. RNA pull-down assay was carried out to evaluate the interaction between miR-138-5p and EGR4 and OCT4. Transwell assay and wound healing assay was used to evaluate the invasive and migratory potential of cells subject to various treatment. The protein levels of Bcl2, Bax, Cl-caspase 3, Cl-PARP and OCT4 were measured in western blotting assay. Results: The levels of ZNF205-AS1, EGR4 and OCT4 were notably upregulated in post-chemotherapy DDP-resistant lung specimens, as opposed to those pre-chemotherapy, and in A549/DDP cells than the progenitor DDP-sensitive A549 cells. In contrast, the level of miR-138-5p was significantly reduced in A549/DDP cells (P<0.05). Luciferase reporter assay confirmed the interaction between ZNF205-AS1 and miRNA-138-5p. Protein-RNA interaction was validated between miR-138-5p, EGR4 and OCT4. The higher chemosensitivity of DDP-resistant cells induced by the loss-of-function of ZNF205-AS1 could be diminished by a miR-138-5p inhibitor. Conclusions: Our data demonstrated that miR-138-5p/OCT4 functions as a downstream effector of the ZNF205-AS1/EGR4 positive feedback loop and mediates resistance of NSCLC cells to DDP. Our work sheds light on the therapeutic strategies for NSCLC with DDP chemoresistance.

Interferon-Gamma-Inducible Protein 16 Inhibits Hepatocellular Carcinoma via Interferon Regulatory Factor 3 on Chemosensitivity.

BACKGROUND AND AIM: Previous reports have suggested IFI16 as a tumor suppressor in hepatocellular carcinoma (HC). Nonetheless, the biological significance of IFI16 and its mechanism concerning resistance to cisplatin (DDP) in HC requires further exploration. METHODS: Samples of tumor and corresponding para-carcinoma tissues were acquired from patients with HC. Furthermore, DDP-resistant cell lines of HC, specifically HCC, Huh7 and Hepatoblastoma, HepG3, were generated by gradually increasing the concentration of DDP. Cell apoptosis and DNA damage were evaluated by utilizing flow cytometry assay and TUNEL staining. The interaction between IFI16 and interferon regulatory factor 3 (IRF3) proteins were analyzed using Co-Immunoprecipitation (Co-IP) assay. In vivo assays were conducted by establishing HC subcutaneous xenograft tumor models. RESULTS: The study found a reduction in IFI16 expression in both HC tissues and DDP-resistant HC cell lines. The binding of IFI16 to IRF3 regulated DNA damage-associated markers in vitro. Overexpression of IFI16 heightened the susceptibility of DDP-induced apoptosis and DNA damage, which was counteracted by IRF3 knockdown, while strengthened by IRF3 overexpression. Moreover, overexpression of IFI16 diminished in vivo DDP-resistant HC tumorigenicity. CONCLUSION: In summary, our findings suggest that IFI16 serves as a tumor suppressor in HC by promoting DNA damage via its interaction with IRF3, thereby reversing DDP resistance.

REG3A promotes proliferation and DDP resistance of ovarian cancer cells by activating the PI3K/Akt signaling pathway.

This study explored the effect of Regenerating Islet-Derived 3-Alpha (REG3A) on ovarian cancer (OC) progression. REG3A expression was scrutinized in clinical tissues of 97 OC cases by quantitative real-time polymerase chain reaction (qRT-PCR). REG3A expression in OC cells and cisplatin (DDP) resistance OC cells was regulated by transfection. LY294002 (10 µM, inhibitor of the PI3K/Akt signaling pathway) was used to treat OC cells and DDP resistance OC cells. Cell counting kit-8 and methyl-thiazolyl-tetrazolium assays were applied for proliferation and DDP resistance detection. Flow cytometry was utilized for cell cycle and apoptosis analysis. The effect of REG3A on the OC cell in vivo growth was researched by establishing xenograft tumor model via using nude mice using nude mice. The expression of genes in clinical samples, cells and xenograft tumor tissues was investigated by qRT-PCR, Western blot and immunohistochemistry. As a result, REG3A was over-expressed in OC patients and cells, associating with dismal prognosis of patients. REG3A knockdown repressed proliferation, DDP resistance, induced cell cycle arrest and apoptosis of OC cells, and reduced the expression MDR-1, Cyclin D1, Cleaved caspase 3 proteins and the PI3K/Akt signaling pathway activity in OC cells. LY294002 treatment abrogated the promotion effect of REG3A on OC cell proliferation, apoptosis inhibition and DDP resistance. REG3A knockdown suppressed the in vivo growth of OC cells. Thus, REG3A promoted proliferation and DDP resistance of OC cells by activating the PI3K/Akt signaling pathway. REG3A might be a promising target for the clinical treatment of OC.

Circ_0000140 Alters miR-527/SLC7A11-Mediated Ferroptosis to Influence Oral Squamous Cell Carcinoma Cell Resistance to DDP.

Background: While there is prior evidence for the ability of circular RNAs (circRNAs) to shape the cisplatin (DDP) resistance of cancers in human patients, there has been relatively little research to date focused on the interplay between circRNAs and DDP resistance in the context of OSCC progression to date. In the present analysis, the functional role that circ_0000140 plays as a mediator of chemoresistance to DDP was thus explored in greater detail. Methods: Both qPCR and Western immunoblotting were employed as appropriate to detect circ_0000140, miR-527, and SLC7A11 levels, while interactions among these factors were detected through RNA immunoprecipitation, RNA pull-down, and dual luciferase report assays. MTT assays were used to assess cellular viability as a means of gauging DDP sensitivity. Results: Both tissue samples from DDP-resistant OSCC patient tumors and OSCC cell lines resistant to DDP exhibited pronounced circ_0000140 upregulation. Knocking down this circRNA significantly increased the DDP sensitivity of both tested DDP-resistant OSCC cell lines and promoted ferroptosis, whereas knocking down miR-527 was sufficient to reverse these effects, which were recapitulated by miR-527 overexpression. Conversely, the effects of overexpressing miR-527 were reversed by the restoration of SLC7A11 expression. Consistently, this circRNA was able to increase DDP IC50 values and to suppress ferroptosis in both tested cell lines through this miR-527/SLC7A11 signaling axis. Conclusion: These results revealed that circ_0000140/miR-527/SLC7A11-mediated ferroptosis may provide novel insights into the development of this cancer type and the emergence of chemoresistance in the future.

Tumor-associated macrophages promote cisplatin resistance in ovarian cancer cells by enhancing WTAP-mediated N6-methyladenosine RNA methylation via the CXCL16/CXCR6 axis.

PURPOSE: Tumor-promotive tumor-associated macrophages (TAMs) and the CXCL16/CXCR6 axis have been reported to be correlated with the limited efficacy of chemotherapy in ovarian cancer (OC). However, the role of TAM-secreted CXCL16 and the mechanism by which it affects the cisplatin (DDP) resistance of OC cells remain elusive. METHODS: We induced human THP-1 monocytes to differentiate into macrophages. Next, SKOV3 and TOV-112D cells were co-cultured with the macrophages, followed by incubation with increasing concentrations of DDP. The effects of CXCL16, CXCR6, and WTAP on the DDP resistance of OC cells were investigated using the CCK-8 assay, colony formation assay, flow cytometry, and TUNEL staining. CXCL16 concentrations were determined by ELISA. Quantitative real-time PCR and western blotting were used to examine related markers. RESULTS: Our results showed that after being co-cultured with TAMs, the DDP resistance of OC cells was significantly enhanced and their CXCL16 levels were elevated. Acquired DDP resistance was characterized by an increased IC50 value for DDP, the formation of cell colonies, and decreased levels of cell apoptosis, which were accompanied by reduced levels of caspase-3 and Bax expression, and increased levels of Bcl-2, PARP1, BRCA1, and BRCA2 expression. Either CXCL16 knockdown in TAMs or CXCR6 knockdown in OC cells suppressed the DDP resistance of OC cells that had been co-cultured with TAMs. Knockdown of CXCL16 affected m6A RNA methylation in OC cells, as reflected by decreased YTHDF1/WTAP expression and increased ALKBH5 expression. WTAP overexpression and knockdown promoted and suppressed the DDP resistance of OC cells, respectively. CONCLUSION: Tumor-associated macrophages promote the cisplatin resistance of OC cells by enhancing WTAP-mediated N6-methyladenosine RNA methylation via the CXCL16/CXCR6 axis.

miR-379-5p regulates the proliferation, cell cycle, and cisplatin resistance of oral squamous cell carcinoma cells by targeting ROR1.

OBJECTIVE: To analyze the regulatory mechanism microRNA miR-379-5p in oral squamous cell carcinoma (OSCC). METHODS: We collected serum samples from patients with OSCC and examined the expression of miR-379-5p and receptor tyrosine kinase-like orphan receptor 1 (ROR1) by real-time polymerase chain reaction and western blot. OSCC cells were purchased for molecular research, cell multiplication was tested using the BrdU assay, cell cycle was tested using flow cytometry, and resistance to cisplatin (DDP) was assessed using the MTT assay. RESULTS: miR-379-5p expression was downregulated and ROR1 expression was upregulated in the serum of OSCC patients, and the area under the curve for OSCC identified by miR-379-5p and ROR1 was not less than 0.800. In the cell function test, overexpression of miR-379-5p could suppress the proliferation, cell cycle, and DDP resistance of OSCC cells. miR-379-5p could negatively regulate ROR1. Inhibition of ROR1 expression had a similar effect after the re-expression of miR-379-5p. Co-overexpression of miR-379-5p and ROR1 counteracted the above inhibitory effects on the proliferation, cell cycle, and DDP resistance of OSCC cells. CONCLUSION: miR-379-5p in OSCC regulates the proliferation, cell cycle, and DDP resistance of tumor cells by targeting ROR1.

NEDD4L inhibits migration, invasion, cisplatin resistance and promotes apoptosis of bladder cancer cells by inactivating the p62/Keap1/Nrf2 pathway.

PURPOSE: This study identified the function of neural precursor cell expressed developmentally down-regulated 4-like (NEDD4L) on bladder cancer (BLCA). METHODS: NEDD4L expression in BLCA patients was scrutinized. The function of NEDD4L on the viability, apoptosis, migration and invasion of BLCA cells was evaluated by cell counting kit-8, flow cytometry and Transwell assays. The effect of NEDD4L on the cisplatin (DDP) resistance of the DDP-resistant BLCA cells was explored. The influence of NEDD4L on the p62/Keap1/Nrf2 pathway activity in BLCA cells was tested by Western blot. Rescue experiments were implemented to verify whether NEDD4L regulated BLCA cell malignant behavior by mediating the Keap1/Nrf2 pathway activity via p62. The effect of NEDD4L on the growth and the p62/Keap1/Nrf2 pathway activity in vivo was researched in xenograft tumor nude mice models. RESULTS: The down-regulated NEDD4L in BLCA patients was associated with unfavorable survival. NEDD4L suppressed the viability (inhibition rate 57.1%/49.0%), migration (inhibition rate 49.7%/77.1%), invasion (inhibition rate 50.6%/75.7%), promoted the apoptosis of T24/5637 cells (promotion rate 243.8%/201.9%), reduced IC 50 of DDP-resistant T24/5637 cells from 132.2/101.8 to 57.81/59.71 µM, respectively, and inactivated the p62/Keap1/Nrf2 pathway in T24/5637 cells. p62 up-regulation partially abrogated the inhibition of NEDD4L on the Keap1/Nrf2 pathway activity, the malignant behavior of BLCA cells, and the DDP resistance of DDP-resistant BLCA cells. NEDD4L overexpression inhibited the tumor growth and the p62/Keap1/Nrf2 pathway activity in vivo in BLCA. CONCLUSION: NEDD4L inhibits the progression of BLCA by inactivating the p62/Keap1/Nrf2 pathway. It may be an effective target for BLCA treatment.

CPSF6-mediated XBP1 3'UTR shortening attenuates cisplatin-induced ER stress and elevates chemo-resistance in lung adenocarcinoma.

Alternative polyadenylation (APA) is a widespread mechanism generating RNA molecules with alternative 3' ends. Herein, we discovered that TargetScan includes a novel XBP1 transcript with a longer 3' untranslated region (UTR) (XBP1-UL) than that included in NCBI. XBP1-UL exhibited a lowered level in blood samples from lung adenocarcinoma (LUAD) patients and in those after DDP treatment. Consistently, XBP1-UL was reduced in A549 cells compared to normal BEAS-2B cells, as well as in DDP-treated/resistant A549 cells relative to controls. Moreover, due to decreased usage of the distal polyadenylation site (PAS) in 3'UTR, XBP1-UL level was lowered in A549 cells and decreased further in DDP-resistant A549 (A549/DDP) cells. Importantly, use of the distal PAS (dPAS) and XBP1-UL level were gradually reduced in A549 cells under increasing concentrations of DDP, which was attributed to DDP-induced endoplasmic reticulum (ER) stress. Furthermore, XBP1 transcripts with shorter 3'UTR (XBP1-US) were more stable and presented stronger potentiation on DDP resistance. The choice of proximal PAS (pPAS) was attributed to CPSF6 elevation, which was caused by BRCA1-distrupted R-loop accumulation in CPSF6 5'end. DDP-induced nuclear LINC00221 also facilitated CPSF6-induced pPAS choice in the pre-XBP1 3'end. Finally, we found that unlike the unspliced XBP1 protein (XBP1-u), the spliced form XBP1-s retarded p53 degradation to facilitate DNA damage repair of LUAD cells. The current study provides new insights into tumor progression and DDP resistance in LUAD, which may contribute to improved LUAD treatment.

miR-125b-5p upregulation by TRIM28 induces cisplatin resistance in non-small cell lung cancer through CREB1 inhibition.

OBJECTIVE: miR-125b-5p plays an important role in the development of cancer and drug resistance. However, in cisplatin resistance of non-small cell lung cancer (NSCLC), the function and potential mechanism of miR-125b-5p is still unclear. The aim of this study was to investigate the role and molecular mechanism of miR-125b-5p in cisplatin resistance of NSCLC. METHODS: A GEO dataset (GSE168707) was analyzed to find high miR-125b-5p levels were associated with DDP resistance. miR-125b-5p expression levels were detected in A549 and A549/DDP cells via real-time quantitative RT-PCR (qRT-PCR). Luciferase reporter assays, western blots and mouse model xenografted were performed to identify CREB1 as a direct target gene of miR-125b-5p. Cell proliferation and apoptosis were also performed to identify whether miR-125b-5p upregulation by TRIM28 induces DDP resistance in NSCLC through CREB1 inhibition. RESULTS: In A549/DDP cells, miR-125b-5p expression was upregulated compared to A549 cells. Then miR-125b-5p was found to increase DDP resistance in NSCLC in vivo and in vitro by increasing cell proliferation and suppressing cell apoptosis. Bioinformatic analyses were used to search for gene which miR-125b-5p can target. We identified miR-125b-5p can regulate CREB1 via luciferase reporter assays, qRT-PCR and western blots. Cell proliferation and apoptosis were also performed to confirm miR-125b-5p could impact on CREB1 and induce the DDP resistance in NSCLC. Additionally, we used bioinformatic analyses to find tripartite motif-containing 28 (TRIM28) as a transcriptional enhance factor of miR-125b-5p. The expression of TRIM28 was upregulated in A549/DDP cells compared with that in A549 cells by qRT-PCR. Finally, we found TRIM28 could mediate DDP resistance through miR-125b-5p/CREB1 axis via cell proliferation, western blot and apoptosis assay. CONCLUSIONS: Overall, our findings demonstrated novel functions and mechanisms underlying DDP resistance in NSCLC through the TRIM28/miR-125b-5p/CREB1 axis. These may serve as novel therapeutic targets to improve the treatment efficacy using DDP for NSCLC in the future.

LINC-PINT suppresses cisplatin resistance in gastric cancer by inhibiting autophagy activation via epigenetic silencing of ATG5 by EZH2.

Resistance to cisplatin (DDP) is a major obstacle in the clinical treatment of advanced gastric cancer (GC). Long noncoding RNA (lncRNA) play a significant regulatory role in the development and drug resistance of GC. In this study, we reported that the lncRNA LINC-PINT was downregulated in DDP-resistant GC cells. Functional studies showed that LINC-PINT inhibited proliferation and migration of DDP-resistant GC cells in vitro, and overexpression of LINC-PINT could enhance the sensitivity of DDP-resistant GC cells to DDP. Further investigation revealed that LINC-PINT recruited enhancer of zeste homolog 2 (EZH2) to the promotor of ATG5 to inhibit its transcription, leading to the suppression of autophagy and DDP resensitization. Collectively, our results revealed how the LINC-PINT/EZH2/ATG5 axis regulates autophagy and DDP resistance in GC. These data suggest that LINC-PINT may be a potential therapeutic target in GC.

Knockdown of lncRNA ACTA2-AS1 reverses cisplatin resistance of ovarian cancer cells via inhibition of miR-378a-3p-regulated Wnt5a.

Cisplatin (DDP) resistance is a principal cause leading to poor prognosis in females suffering from ovarian cancer (OC). Long non-coding RNA (lncRNA) has been shown to have an involvement in regulating cellular processes; chemoresistance being one of them the precise object of this work was to probe into the role of lncRNA ACTA2-AS1 in OC cells that have developed DDP resistance. We developed DDP-resistant OC cell lines (A2780/DDP and SKOV3/DDP). The influence of the ACTA2-AS1/miR-378a-3p/Wnt5a axis on DDP chemoresistance of DDP-resistant OC cells was ascertained using real-time PCR, Elisa, and CCK-8, and dual-luciferase reporter assay. In DDP-resistant cells and tissues, ACTA2-AS1 was increased, while a substantial downregulation in miR-378a-3p was noticed. In cells manifesting DDP-resistance, knocking down ACTA2-AS1 boosted the expression of miR-378a-3p. Further research into the mechanism of ACTA2-AS1 revealed that it acted as a 'sponge' by getting involved in a competition against miR-378a-3p binding to modify its target Wnt5a. The suppression of DDP-resistance in OC cells caused by ACTA2-AS1 downregulation was reversed by silencing miR-378a-3p. Furthermore, via inhibition of Wnt5a, miR-378a-3p alleviated DDP resistance in OC cells. These findings show that for miR-378a-3p, ACTA2-AS1 works like a sponge thus preventing it from binding to Wnt5a and boosting OC cell DDP resistance. Our research will aid the expansion of plausible therapeutic options for treating OC.

Circular RNA hsa_circ_0000277 promotes tumor progression and DDP resistance in esophageal squamous cell carcinoma.

BACKGROUND: Circular RNAs (circRNAs) are well-known regulators of cancer progression and chemoresistance in various types of cancers. This study was performed to investigate the function of hsa_circ_0000277 in esophageal squamous cell carcinoma (ESCC). METHODS: RNA levels were analyzed via the reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Cell Counting Kit-8 (CCK-8) assay was applied to determine cell proliferation and half maximal inhibitory concentration (IC50) of cisplatin (DDP). Colony formation ability was evaluated by colony formation assay. Cell cycle and apoptosis were measured using flow cytometry. RNA immunoprecipitation (RIP), pull-down assay and dual-luciferase reporter assays were performed for target interaction analysis. The protein levels were determined through western blot. Xenograft models were established for researching hsa_circ_0000277 function in vivo. RESULTS: Hsa_circ_0000277 expression was increased in ESCC cells and tissues, and it had important clinical significance. Downregulation of hsa_circ_0000277 repressed ESCC cell proliferation, colony formation, cell cycle, and DDP resistance. Hsa_circ_0000277 acted as a microRNA-873-5p (miR-873-5p) sponge and Sry-related high-mobility group box 4 (SOX4) was validated as a target of miR-873-5p. Moreover, hsa_circ_0000277/miR-873-5p axis and miR-873-5p/SOX4 axis regulated ESCC cell progression and DDP resistance. Hsa_circ_0000277/miR-873-5p axis activated SOX4/Wnt/ß-catenin signaling pathway. Hsa_circ_0000277 facilitated tumorigenesis and DDP resistance by miR-873-5p/SOX4 axis in vivo. CONCLUSION: These findings unraveled that hsa_circ_0000277 promoted ESCC progression and DDP resistance via miR-873-5p/SOX4/Wnt/ß-catenin axis, showing a specific molecular mechanism of carcinogenesis and chemoresistance in ESCC.

PI3K/Akt/FOXO3a signaling pathway inducing protective autophagy promotes acquired lung adenocarcinoma resistance remodeling to DDP / 中国临床药理学与治疗学

AIM: To investigate the mechanism of acquired resistance remodeling to DDP (named cisplatin) by comparing the level of autophagy between the parental and DDP-resistant cells. METHODS: Human lung adenocarcinoma A549 (parental cells) and A549/DDP cells (DDP-resistant cells) were treated with different concentrations of DDP, the drug resistance index (RI) was determined by CCK-8 assay and the autophagy associated proteins, like Beclin 1, LC3Ⅱ and p62 were measured by Western blot. A549 and A549/DDP cells were treated with 10 μmol/L DDP (about IC50 of A549 cells), the cell viability was determined by CCK-8 assay, the autophagy and apoptosis associated proteins (including Beclin 1, LC3Ⅱ, p62, Bcl-2, Bax and cleaved-caspase 3) were measured by Western blot, and the activity of transcription factor FOXO3a and its subcellular localization were detected by Western blot and laser confocal scanning microscopy. Finally, the autophagy inhibitor Baflomycin A1 (Baf A1) and the protein kinase inhibitor of PI3K/Akt signaling pathway were co-treated with DDP respectively to test the mechanism of drug resistance. RESULTS: Compared with the parental A549 cells, the acquired resistant A549/DDP cells showed DDP-resistance and higher level of basal autophagy. More survival count of A549/DDP cells than that of A549 cells in the same environment stress of 10 μmol/L DDP. 10 μmol/L DDP induced A549 cells apoptosis by down-regulated Bcl-2, and increased Bax and cleaved-caspase 3, which followed the inhibition of PI3K/Akt signaling pathway and up-regulated the expression level of transcription factor FOXO3a. While the same concentration of DDP activated A549/DDP cells autophagy by up-regulated Beclin 1 and LC3Ⅱ, down-regulated p62, which followed the inhibition of PI3K/Akt signaling pathway and inhibited the phosphorylation of FOXO3a. CONCLUSION: DDP induces apoptosis by up-regulating the transcription factor FOXO3a via inhibiting the PI3K/Akt/FOXO3a signaling pathway in A549 cells, while activating autophagy by inducing the phosphorylation of FOXO3a via inhibiting the PI3K/Akt/FOXO3a signaling pathway in A549/DDP cells.

TPL Inhibits the Invasion and Migration of Drug-Resistant Ovarian Cancer by Targeting the PI3K/AKT/NF-κB-Signaling Pathway to Inhibit the Polarization of M2 TAMs.

Chemoresistance is the primary reason for the poor prognosis of patients with ovarian cancer, and the search for a novel drug treatment or adjuvant chemotherapy drug is an urgent need. The tumor microenvironment plays key role in the incidence and development of tumors. As one of the most important components of the tumor microenvironment, M2 tumor-associated macrophages are closely related to tumor migration, invasion, immunosuppressive phenotype and drug resistance. Many studies have confirmed that triptolide (TPL), one of the principal components of Tripterygium wilfordii, possesses broad-spectrum anti-tumor activity. The aims of this study were to determine whether TPL could inhibit the migration and invasion of A2780/DDP cells in vitro and in vivo by inhibiting the polarization of M2 tumor-associated macrophages (TAMs); to explore the mechanism(s) underlying TPL effects; and to investigate the influence of TPL on murine intestinal symbiotic microbiota. In vitro results showed that M2 macrophage supernatant slightly promoted the proliferation, invasion, and migration of A2780/DDP cells, which was reversed by TPL in a dose-dependent manner. Animal experiments showed that TPL, particularly TPL + cisplatin (DDP), significantly reduced the tumor burden, prolonged the life span of mice by inhibiting M2 macrophage polarization, and downregulated the levels of CD31 and CD206 (CD31 is the vascular marker and CD206 is the macrophage marker), the mechanism of which may be related to the inhibition of the PI3K/Akt/NF-κB signaling pathway. High-throughput sequencing results of the intestinal microbiota in nude mice illustrated that Akkermansia and Clostridium were upregulated by DDP and TPL respective. We also found that Lactobacillus and Akkermansia were downregulated by DDP combined with TPL. Our results highlight the importance of M2 TAMs in Epithelial Ovarian Cancer (EOC) migration ability, invasiveness, and resistance to DDP. We also preliminarily explored the mechanism governing the reversal of the polarization of M2 macrophages by TPL.