Shengli Li

HIF‐1α‐induced long noncoding RNA LINC02776 promotes drug resistance of ovarian cancer by increasing polyADP‐ribosylation

AbstractBackgroundChemoresistance remains a major hurdle in ovarian cancer (OC) treatment, as many patients eventually develop resistance to platinum‐based chemotherapy and/or PARP inhibitors (PARPi).MethodsWe performed transcriptome‐wide analysis by RNA sequencing (RNA‐seq) data of platinum‐resistant and ‐sensitive OC tissues. We demonstrated the role of LINC02776 in platinum resistance in OC cells, mice models and patient‐derived organoid (PDO) models.ResultsWe identify the long noncoding RNA LINC02776 as a critical factor of platinum resistance. Elevated expression of LINC02776 is observed in platinum‐resistant OC and serves as an independent prognostic factor for OC patients. Functionally, silencing LINC02776 reduces proliferation and DNA damage repair in OC cells, thereby enhancing sensitivity to platinum and PARPi in both xenograft mouse models and patient‐derived organoid (PDO) models with acquired chemoresistance. Mechanistically, LINC02776 binds to the catalytic domain of poly (ADP‐ribose) polymerase 1 (PARP1), promoting PARP1‐dependent polyADP‐ribosylation (PARylation) and facilitating homologous recombination (HR) restoration. Additionally, high HIF‐1α expression in platinum‐resistant tissues further stimulates LINC02776 transcription.ConclusionsOur findings suggest that targeting LINC02776 represents a promising therapeutic strategy for OC patients who have developed resistance to platinum or PARPi.Key points LINC02776 promotes OC cell proliferation by regulating DNA damage and apoptosis signaling pathways. LINC02776 binds PARP1 to promote DNA damage‐triggered PARylation in OC cells. LINC02776 mediates cisplatin and olaparib resistance in OC cells by enhancing PARP1‐mediated PARylation activity and regulating the PARP1‐mediated HR pathway. The high expression of LINC02776 is induced by HIF‐1α in platinum‐resistant OC cells and tissues.

Cisplatin-induced PANDAR-Chemo-EVs contribute to a more aggressive and chemoresistant ovarian cancer phenotype through the SRSF9-SIRT4/SIRT6 axis

We previously elucidated that long non-coding RNA Promoter of CDKN1A Antisense DNA damage Activated RNA (PANDAR) as a p53-dependent oncogene to promote cisplatin resistance in ovarian cancer (OC). Intriguingly, high level of p53-independent PANDAR was found in cisplatin-resistant patients with p53 mutation. Here, our study probed the new roles and the underlying mechanisms of PANDAR in p53-mutant OC cisplatin-resistance. A2780 and A2780-DDP cells were served as OC cisplatin-sensitive and cisplatin-resistant cells. HO-8910PM cells were subjected to construct chemotherapy-induced extracellular vesicles (Chemo-EVs). Transmission electron microscopy (TEM) and nanoparticle tracking analysis were employed to evaluate Chemo-EVs. Cell viability was assessed using cell counting kit-8 and colony formation assays. Cell apoptosis was assessed using Annexin V and propidium iodide staining. The relationships between PANDAR, serine and arginine-rich pre-mRNA splicing factor 9 (SRSF9) were verified by RNA immunoprecipitation and fluorescence in situ hybridization. Tumor xenograft experiment was employed to evaluate the effects of PANDAR-Chemo-EVs on OC cisplatin-resistance in vivo. Immunofluorescent staining and immunohistochemistry were performed in tumor tissue. PANDAR level increased in OC patients with p53-mutation. PANDAR efflux enacted via exosomes under cisplatin conditions. Additionally, exosomes from OC cell lines carried PANDAR, which significantly increased cell survival and chemoresistance in vitro and tumor progression and metastasis in vivo. During cisplatin-induced stress, SRSF9 was recruited to nuclear bodies by increased PANDAR and muted apoptosis in response to cisplatin. Besides, SRSF9 significantly increased the ratio of SIRT4/SIRT6 mRNA in OC. Cisplatin-induced exosomes transfer PANDAR and lead to a rapid adaptation of OC cell survival through accumulating SRSF9 following cisplatin stress exposure.

AUF1-induced circular RNA hsa_circ_0010467 promotes platinum resistance of ovarian cancer through miR-637/LIF/STAT3 axis

Increasing evidences has indicated that primary and acquired resistance of ovarian cancer (OC) to platinum is mediated by multiple molecular and cellular factors. Understanding these mechanisms could promote the therapeutic efficiency for patients with OC. Here, we screened the expression pattern of circRNAs in samples derived from platinum-resistant and platinum-sensitive OC patients using RNA-sequencing (RNA-seq). The expression of hsa_circ_0010467 was validated by Sanger sequencing, RT-qPCR, and fluorescence in situ hybridization (FISH) assays. Overexpression and knockdown experiments were performed to explore the function of hsa_circ_0010467. The effects of hsa_circ_0010467 on enhancing platinum treatment were validated in OC cells, mouse model and patient-derived organoid (PDO). RNA pull-down, RNA immunoprecipitation (RIP), and dual-luciferase reporter assays were performed to investigate the interaction between hsa_circ_0010467 and proteins. Increased expression of hsa_circ_0010467 is observed in platinum-resistant OC cells, tissues and serum exosomes, which is positively correlated with advanced tumor stage and poor prognosis of OC patients. Hsa_circ_0010467 is found to maintain the platinum resistance via inducing tumor cell stemness, and silencing hsa_circ_0010467 substantially increases the efficacy of platinum treatment on inhibiting OC cell proliferation. Further investigation reveals that hsa_circ_0010467 acts as a miR-637 sponge to mediate the repressive effect of miR-637 on leukemia inhibitory factor (LIF) and activates the LIF/STAT3 signaling pathway. We further discover that AUF1 could promote the biogenesis of hsa_circ_0010467 in OC. Our study uncovers the mechanism that hsa_circ_0010467 mediates the platinum resistance of OC through AUF1/hsa_circ_0010467/miR-637/LIF/STAT3 axis, and provides potential targets for the treatment of platinum-resistant OC patients.

Single-cell transcriptomics reveals cellular heterogeneity and molecular stratification of cervical cancer

AbstractCervical cancer (CC) is the most common gynecological malignancy, whose cellular heterogeneity has not been fully understood. Here, we performed single-cell RNA sequencing (scRNA-seq) to survey the transcriptomes of 57,669 cells derived from three CC tumors with paired normal adjacent non-tumor (NAT) samples. Single-cell transcriptomics analysis revealed extensive heterogeneity in malignant cells of human CCs, wherein epithelial subpopulation exhibited different genomic and transcriptomic signatures. We also identified cancer-associated fibroblasts (CAFs) that may promote tumor progression of CC, and further distinguished inflammatory CAF (iCAF) and myofibroblastic CAF (myCAF). CD8+ T cell diversity revealed both proliferative (MKI67+) and non-cycling exhausted (PDCD1+) subpopulations at the end of the trajectory path. We used the epithelial signature genes derived from scRNA-seq to deconvolute bulk RNA-seq data of CC, identifying four different CC subtypes, namely hypoxia (S-H subtype), proliferation (S-P subtype), differentiation (S-D subtype), and immunoactive (S-I subtype) subtype. The S-H subtype showed the worst prognosis, while CC patients of the S-I subtype had the longest overall survival time. Our results lay the foundation for precision prognostic and therapeutic stratification of CC.