HMGB3 promotes PARP inhibitor resistance through interacting with PARP1 in ovarian cancer

Comprehensive bioinformatics analysis identified HMGB3 as a promising immunotherapy target for glioblastoma multiforme

OBJECTIVE

Glioblastoma multiforme (GBM) presents significant therapeutic challenges due to its heterogeneous tumorigenicity, drug resistance, and immunosuppression. Although several molecular markers have been developed, there still lack of sensitive molecular for accurately detection. Studying the mechanisms underlying the development of GBM and finding relevant prognostic biomarkers remains crucial.

METHODS

Single-cell RNA sequencing, bulk RNA-seq, and cancer immune cycle activities of GBM were used to assess the expression of different molecular related to GBM. Bioinformatics analyses were carried to evaluate the functional of the high mobility group protein B3 (HMGB3) in GBM.

RESULTS

HMGB3 was highly expressed in GBM tissues and influenced the interpatient and intratumoral transcriptomic heterogeneity as well as immunosuppression in GBM. HMGB3 also contributes to a no inflamed tumor microenvironment (TME) and has an inhibitory effect on tumor-associated immune cell infiltration. Besides, HMGB3 participated GBM chemotherapeutic sensitivity and negative correlation with 140 medicines.

CONCLUSION

HMGB3 as a heterogeneous and immunosuppressive molecule in the GBM TME, making it a potential target for precision therapy for GBM.

Integrative Bioinformatic Analysis of Cellular Senescence Genes in Ovarian Cancer: Molecular Subtyping, Prognostic Risk Stratification, and Chemoresistance Prediction

Background: Ovarian cancer (OC) is a heterogeneous malignancy associated with a poor prognosis, necessitating robust biomarkers for risk stratification and therapy optimization. Cellular senescence-related genes (CSGs) are emerging as pivotal regulators of tumorigenesis and immune modulation, yet their prognostic and therapeutic implications in OC remain underexplored. Methods: We integrated RNA-sequencing data from TCGA-OV (n = 376), GTEx (n = 88), and GSE26712 (n = 185) to identify differentially expressed CSGs (DE-CSGs). Consensus clustering, Cox regression, LASSO-penalized modeling, and immune infiltration analyses were employed to define molecular subtypes, construct a prognostic risk score, and characterize tumor microenvironment (TME) dynamics. Drug sensitivity was evaluated using the Genomics of Drug Sensitivity in Cancer (GDSC)-derived chemotherapeutic response profiles. Results: Among 265 DE-CSGs, 31 were prognostic in OC, with frequent copy number variations (CNVs) in genes such as STAT1, FOXO1, and CCND1. Consensus clustering revealed two subtypes (C1/C2): C2 exhibited immune-rich TME, elevated checkpoint expression (PD-L1, CTLA4), and poorer survival. A 19-gene risk model stratified patients into high-/low-risk groups, validated in GSE26712 (AUC: 0.586-0.713). High-risk patients showed lower tumor mutation burden (TMB), immune dysfunction, and resistance to Docetaxel/Olaparib. Six hub genes (HMGB3, MITF, CKAP2, ME1, CTSD, STAT1) were independently predictive of survival. Conclusions: This study establishes CSGs as critical determinants of OC prognosis and immune evasion. The molecular subtypes and risk model provide actionable insights for personalized therapy, while identified therapeutic vulnerabilities highlight opportunities to overcome chemoresistance through senescence-targeted strategies.

PARP inhibitors in ovarian cancer: Mechanisms of resistance and implications to therapy

Advanced epithelial ovarian cancer of the high-grade serous subtype (HGSOC) remains a significant clinical challenge due to the development of resistance to current platinum-based chemotherapies. PARP1/2 inhibitors (PARPi) exploit the well-characterised homologous recombination repair deficiency (HRD) in HGSOC and offer an effective targeted approach to treatment. Several clinical trials demonstrated that PARPi (olaparib, rucaparib, niraparib) significantly improved progression-free survival (PFS) in HGSOC in the recurrent maintenance setting. However, 40-70 % of patients develop Resistance to PARPi presenting an ongoing challenge in the clinic. Therefore, there is an unmet need for novel targeted therapies and biomarkers to identify intrinsic or acquired resistance to PARPi in ovarian cancer. Understanding the mechanisms of resistance to PARPi is crucial for identifying molecular vulnerabilities, developing effective biomarkers for patient stratification and guiding treatment decisions. Here, we summarise the current landscape of mechanisms associated with PARPi resistance such as restored homologous recombination repair functionality, replication fork stability and alterations to PARP1 and PARP2 and the DNA damage response. We highlight the role of circulating tumour DNA (ctDNA) in identifying acquired resistance biomarkers and its potential in guiding 'real-time' treatment decisions. Moreover, we explore other innovative treatment strategies aimed at overcoming specific resistance mechanisms, including the inhibition of ATR, WEE1 and POLQ. We also examine the role of PARPi rechallenge in patients with acquired resistance.

PARP1: A comprehensive review of its mechanisms, therapeutic implications and emerging cancer treatments

The Poly (ADP-ribose) polymerase-1 (PARP1) enzyme is involved in several signalling pathways related to homologous repair (HR), base excision repair (BER), and non-homologous end joining (NHEJ). Studies demonstrated that the deregulation of PARP1 function and control mechanisms can lead to cancer emergence. On the other side, PARP1 can be a therapeutic target to maximize cancer treatment. This is done by molecules that can modulate radiation effects, such as DNA repair inhibitors (PARPi). With this approach, tumour cell viability can be undermined by targeting DNA repair mechanisms. Thus, treatment using PARPi represents a new era for cancer therapy, and even new horizons can be attained by coupling these molecules with a nano-delivery system. For this, drug delivery systems such as liposomes encompass all the required features due to its excellent biocompatibility, biodegradability, and low toxicity. This review presents a comprehensive overview of PARP1 biological features and mechanisms, its role in cancer development, therapeutic implications, and emerging cancer treatments by PARPi-mediated therapies. Although there are a vast number of studies regarding PARP1 biological function, some PARP1 mechanisms are not clear yet, and full-length PARP1 structure is missing. Nevertheless, literature reports demonstrate already the high usefulness and vast possibilities offered by combined PARPi cancer therapy.

Reversing regulatory safeguards: Targeting the ATR pathway to overcome PARP inhibitor resistance

The development of poly (ADP-ribose) polymerase inhibitors (PARPis) is widely considered a therapeutic milestone in the management of BRCA1/2-deficient malignancies. Since a growing number of cancer treatment guidelines include PARPis, the inevitably emerging PARPi resistance becomes a serious limitation that must be addressed. Targeting the DNA damage response signaling kinase, ATR (ataxia telangiectasia and rad3-related serine/threonine kinase), activated in response to PARPi-induced replication stress, represents a promising approach in fighting PARPi-resistant cancers. The success of this combination therapy in preclinical models has inspired efforts to translate its potential through extensive clinical research and clinical trials. However, the available clinical evidence suggests that PARPi/ATRi combinations have yet to reach their anticipated therapeutic potential. In this review, we summarize work elucidating mechanisms underpinning the effectiveness of ATRi in fighting PARPi resistance and review translational studies reporting efficacy in different types of cancer. Finally, we discuss potential biomarkers of patient selection for customized combinations of PARPi/ATRi treatments.

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

BACKGROUND

Chemoresistance remains a major hurdle in ovarian cancer (OC) treatment, as many patients eventually develop resistance to platinum-based chemotherapy and/or PARP inhibitors (PARPi).

METHODS

We 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.

RESULTS

We 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.

CONCLUSIONS

Our 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.

Survival analysis of recurrent ovarian cancer under different PARP inhibitor treatment patterns: a single-center retrospective study

Objective

To compare the effects of different treatment modes containing PARPis and traditional treatment modes on the survival of patients with recurrent ovarian cancer.

Methods

From December 2012 to December 2023, 131 recurrent ovarian cancer patients were screened. The patients were followed up retrospectively, and the relevant data was collected and analyzed.

Results

Eighty-three patients used PARPis throughout the treatment process, and the median OS was not reached. Forty-eight patients did not use PARPis, and the median OS was 45.4 months. The two groups ' BRCA gene status, NACT, postoperative residual disease status, and PFI differ (P < 0.05). There was no significant difference in recurrence characteristics between the PARPis use and non-use groups in first-line maintenance therapy (P < 0.05). The use of PARPis, CA125 level and PFI were the independent influencing factors of OS in patients with recurrent ovarian cancer (P < 0.05). The median OS of patients with PARPis maintenance treatment in the single-line, second-line and last-line has not been reached. The median OS in the multi-line group was 69.5 months.

Conclusion

The use of PARPis, CA125 level and PFI were independent influencing factors of OS in patients with recurrent ovarian cancer. The first-line maintenance use of PARPis will not cause differences in disease recurrence characteristics. Compared with the patients without PARPis, patients with recurrent ovarian cancer receiving PARPis maintenance therapy have longer OS. The group of patients with PARPis maintenance treatment in the second and last lines showed better OS (P < 0.05). However, OS was not significantly different between the second-line and last-line groups (P < 0.05). There was no significant difference in OS between the multiple-line use PARPis and single-line use PARPis groups.

The recent advance and prospect of poly(ADP-ribose) polymerase inhibitors for the treatment of cancer

Chemotherapies are commonly used in cancer therapy, their applications are limited to low specificity, severe adverse reactions, and long-term medication-induced drug resistance. Poly(ADP-ribose) polymerase (PARP) inhibitors are a novel class of antitumor drugs developed to solve these intractable problems based on the mechanism of DNA damage repair, which have been widely applied in the treatment of ovarian cancer, breast cancer, and other cancers through inducing synthetic lethal effect and trapping PARP-DNA complex in BRCA gene mutated cancer cells. In recent years, PARP inhibitors have been widely used in combination with various first-line chemotherapy drugs, targeted drugs and immune checkpoint inhibitors to expand the scope of clinical application. However, the intricate mechanisms underlying the drug resistance to PARP inhibitors, including the restoration of homologous recombination, stabilization of DNA replication forks, overexpression of drug efflux protein, and epigenetic modifications pose great challenges and desirability in the development of novel PARP inhibitors. In this review, we will focus on the mechanism, structure-activity relationship, and multidrug resistance associated with the representative PARP inhibitors. Furthermore, we aim to provide insights into the development prospects and emerging trends to offer guidance for the clinical application and inspiration for the development of novel PARP inhibitors and degraders.

HOXA11-As Promotes Lymph Node Metastasis Through Regulation of IFNL and HMGB Family Genes in Pancreatic Cancer

Recent studies have shown that long noncoding RNAs (lncRNAs) play pivotal roles in the development and progression of cancer. In the present study, we aimed to identify lncRNAs associated with lymph node metastasis in pancreatic ductal adenocarcinoma (PDAC). We analyzed data from The Cancer Genome Atlas (TCGA) database to screen for genes overexpressed in primary PDAC tumors with lymph node metastasis. Our screen revealed 740 genes potentially associated with lymph node metastasis, among which were multiple lncRNA genes located in the HOXA locus, including HOXA11-AS. Elevated expression of HOXA11-AS was associated with more advanced tumor stages and shorter overall survival in PDAC patients. HOXA11-AS knockdown suppressed proliferation and migration of PDAC cells. RNA-sequencing analysis revealed that HOXA11-AS knockdown upregulated interferon lambda (IFNL) family genes and downregulated high-mobility group box (HMGB) family genes in PDAC cells. Moreover, HMGB3 knockdown suppressed proliferation and migration by PDAC cells. These results suggest that HOXA11-AS contributes to PDAC progression, at least in part, through regulation of IFNL and HMGB family genes and that HOXA11 AS is a potential therapeutic target in PDAC.

Biomarkers in high grade serous ovarian cancer

High-grade serous ovarian cancer (HGSC) is the most common subtype of ovarian cancer. HGSC patients typically present with advanced disease, which is often resistant to chemotherapy and recurs despite initial responses to therapy, resulting in the poor prognosis associated with this disease. There is a need to utilise biomarkers to manage the various aspects of HGSC patient care. In this review we discuss the current state of biomarkers in HGSC, focusing on the various available immunohistochemical (IHC) and blood-based biomarkers, which have been examined for their diagnostic, prognostic and theranostic potential in HGSC. These include various routine clinical IHC biomarkers such as p53, WT1, keratins, PAX8, Ki67 and p16 and clinical blood-borne markers and algorithms such as CA125, HE4, ROMA, RMI, ROCA, and others. We also discuss various components of the liquid biopsy as well as a number of novel IHC biomarkers and non-routine blood-borne biomarkers, which have been examined in various ovarian cancer studies. We also discuss the future of ovarian cancer biomarker research and highlight some of the challenges currently facing the field.

Deciphering the roles of the HMGB family in cancer: Insights from subcellular localization dynamics

The high-mobility group box (HMGB) family consists of four DNA-binding proteins that regulate chromatin structure and function. In addition to their intracellular functions, recent studies have revealed their involvement as extracellular damage-associated molecular patterns (DAMPs), contributing to immune responses and tumor development. The HMGB family promotes tumorigenesis by modulating multiple processes including proliferation, metabolic reprogramming, metastasis, immune evasion, and drug resistance. Due to the predominant focus on HMGB1 in the literature, little is known about the remaining members of this family. This review summarizes the structural, distributional, as well as functional similarities and distinctions among members of the HMGB family, followed by a comprehensive exploration of their roles in tumor development. We emphasize the distributional and functional hierarchy of the HMGB family at both the organizational and subcellular levels, with a focus on their relationship with the tumor immune microenvironment (TIME), aiming to prospect potential strategies for anticancer therapy.

Structure and Functions of HMGB3 Protein

HMGB3 protein belongs to the group of HMGB proteins from the superfamily of nuclear proteins with high electrophoretic mobility. HMGB proteins play an active part in almost all cellular processes associated with DNA-repair, replication, recombination, and transcription-and, additionally, can act as cytokines during infectious processes, inflammatory responses, and injuries. Although the structure and functions of HMGB1 and HMGB2 proteins have been intensively studied for decades, very little attention has been paid to HMGB3 until recently. In this review, we summarize the currently available data on the molecular structure, post-translational modifications, and biological functions of HMGB3, as well as the possible role of the ubiquitin-proteasome system-dependent HMGB3 degradation in tumor development.

High expression circRALGPS2 in atretic follicle induces chicken granulosa cell apoptosis and autophagy via encoding a new protein

BACKGROUND

The reproductive performance of chickens mainly depends on the development of follicles. Abnormal follicle development can lead to decreased reproductive performance and even ovarian disease among chickens. Chicken is the only non-human animal with a high incidence of spontaneous ovarian cancer. In recent years, the involvement of circRNAs in follicle development and atresia regulation has been confirmed.

RESULTS

In the present study, we used healthy and atretic chicken follicles for circRNA RNC-seq. The results showed differential expression of circRALGPS2. It was then confirmed that circRALGPS2 can translate into a protein, named circRALGPS2-212aa, which has IRES activity. Next, we found that circRALGPS2-212aa promotes apoptosis and autophagy in chicken granulosa cells by forming a complex with PARP1 and HMGB1.

CONCLUSIONS

Our results revealed that circRALGPS2 can regulate chicken granulosa cell apoptosis and autophagy through the circRALGPS2-212aa/PARP1/HMGB1 axis.

HMGB1/RAGE axis in tumor development: unraveling its significance

High mobility group protein 1 (HMGB1) plays a complex role in tumor biology. When released into the extracellular space, it binds to the receptor for advanced glycation end products (RAGE) located on the cell membrane, playing an important role in tumor development by regulating a number of biological processes and signal pathways. In this review, we outline the multifaceted functions of the HMGB1/RAGE axis, which encompasses tumor cell proliferation, apoptosis, autophagy, metastasis, and angiogenesis. This axis is instrumental in tumor progression, promoting tumor cell proliferation, autophagy, metastasis, and angiogenesis while inhibiting apoptosis, through pivotal signaling pathways, including MAPK, NF-κB, PI3K/AKT, ERK, and STAT3. Notably, small molecules, such as miRNA-218, ethyl pyruvate (EP), and glycyrrhizin exhibit the ability to inhibit the HMGB1/RAGE axis, restraining tumor development. Therefore, a deeper understanding of the mechanisms of the HMGB1/RAGE axis in tumors is of great importance, and the development of inhibitors targeting this axis warrants further exploration.

Mechanism of PARP inhibitor resistance and potential overcoming strategies

PARP inhibitors (PARPi) are a kind of cancer therapy that targets poly (ADP-ribose) polymerase. PARPi is the first clinically approved drug to exert synthetic lethality by obstructing the DNA single-strand break repair process. Despite the significant therapeutic effect in patients with homologous recombination (HR) repair deficiency, innate and acquired resistance to PARPi is a main challenge in the clinic. In this review, we mainly discussed the underlying mechanisms of PARPi resistance and summarized the promising solutions to overcome PARPi resistance, aiming at extending PARPi application and improving patient outcomes.

ADP-ribose contributions to genome stability and PARP enzyme trapping on sites of DNA damage; paradigm shifts for a coming-of-age modification

ADP-ribose is a versatile modification that plays a critical role in diverse cellular processes. The addition of this modification is catalyzed by ADP-ribosyltransferases, among which notable poly(ADP-ribose) polymerase (PARP) enzymes are intimately involved in the maintenance of genome integrity. The role of ADP-ribose modifications during DNA damage repair is of significant interest for the proper development of PARP inhibitors targeted toward the treatment of diseases caused by genomic instability. More specifically, inhibitors promoting PARP persistence on DNA lesions, termed PARP "trapping," is considered a desirable characteristic. In this review, we discuss key classes of proteins involved in ADP-ribose signaling (writers, readers, and erasers) with a focus on those involved in the maintenance of genome integrity. An overview of factors that modulate PARP1 and PARP2 persistence at sites of DNA lesions is also discussed. Finally, we clarify aspects of the PARP trapping model in light of recent studies that characterize the kinetics of PARP1 and PARP2 recruitment at sites of lesions. These findings suggest that PARP trapping could be considered as the continuous recruitment of PARP molecules to sites of lesions, rather than the physical stalling of molecules. Recent studies and novel research tools have elevated the level of understanding of ADP-ribosylation, marking a coming-of-age for this interesting modification.

Obesity exacerbates postoperative cognitive dysfunction by activating the PARP1/NAD+/SIRT1 axis through oxidative stress

The purposes of this study were to explore the impact of obesity on postoperative cognitive dysfunction (POCD) and to investigate the underlying mechanism by which obesity exacerbates POCD. In this study, fifteen-month-old male C57BL/6 J mice were fed a High-fat diet for three months to establish obesity models. Internal fixation of tibial fractures under isoflurane inhalation was performed to construct a POCD animal model. Three days after surgery, mice were subjected to the Morris water maze (MWM) experiment to evaluate their learning and memory abilities. The findings from the MWM experiment revealed that in comparison to the Ad Libitum Surgical group (ALS), mice in the High-fat Surgical group (HFS) exhibited prolonged escape latencies and reduced platform crossings. These outcomes suggest the potential exacerbating role of obesity in cognitive impairment within the POCD mouse models. Immunofluorescence (IF) findings demonstrate that obesity intensifies anesthesia and surgery-induced oxidative stress levels within the hippocampus. Compared to the Ad Libitum Control group (ALC), an elevation in PARP1 expression and a reduction in the NAD+/NADH ratio and SIRT1 expression were observed in the hippocampus of mice from the ALS. Moreover, when contrasting the HFS group with the ALS group, increased PARP1 expression along with decreased NAD+/NADH ratio and SIRT1 expression were evident. In vitro studies found that compared with the Control group (CON), oil red staining and BODIPY probe staining showed significant lipid droplet aggregation in the palmitic acid (PA) group. IF results demonstrated that HT22 cells in the PA group experienced oxidative stress and activation of the PARP1/NAD+/SIRT1 axis in contrast to the CON group. Moreover, manipulation of PARP1 expression in HT22 cells through PARP1 lentivirus-based silencing or overexpression revealed a converse relationship between PARP1 expression levels and the NAD+/NADH ratio as well as SIRT1 expression levels. This study concludes that obesity may exacerbate POCD by triggering activation of the oxidative stress-induced PARP1/NAD+/SIRT1 axis.

The dynamic process of covalent and non-covalent PARylation in the maintenance of genome integrity: a focus on PARP inhibitors

Poly(ADP-ribosylation) (PARylation) by poly(ADP-ribose) polymerases (PARPs) is a highly regulated process that consists of the covalent addition of polymers of ADP-ribose (PAR) through post-translational modifications of substrate proteins or non-covalent interactions with PAR via PAR binding domains and motifs, thereby reprogramming their functions. This modification is particularly known for its central role in the maintenance of genomic stability. However, how genomic integrity is controlled by an intricate interplay of covalent PARylation and non-covalent PAR binding remains largely unknown. Of importance, PARylation has caught recent attention for providing a mechanistic basis of synthetic lethality involving PARP inhibitors (PARPi), most notably in homologous recombination (HR)-deficient breast and ovarian tumors. The molecular mechanisms responsible for the anti-cancer effect of PARPi are thought to implicate both catalytic inhibition and trapping of PARP enzymes on DNA. However, the relative contribution of each on tumor-specific cytotoxicity is still unclear. It is paramount to understand these PAR-dependent mechanisms, given that resistance to PARPi is a challenge in the clinic. Deciphering the complex interplay between covalent PARylation and non-covalent PAR binding and defining how PARP trapping and non-trapping events contribute to PARPi anti-tumour activity is essential for developing improved therapeutic strategies. With this perspective, we review the current understanding of PARylation biology in the context of the DNA damage response (DDR) and the mechanisms underlying PARPi activity and resistance.

HMGB3 promotes the malignant phenotypes and stemness of epithelial ovarian cancer through the MAPK/ERK signaling pathway

BACKGROUND

Ovarian cancer, particularly epithelial ovarian cancer (EOC), is the leading cause of cancer-related mortality among women. Our previous study revealed that high HMGB3 levels are associated with poor prognosis and lymph node metastasis in patients with high-grade serous ovarian carcinoma; however, the role of HMGB3 in EOC proliferation and metastasis remains unknown.

METHODS

MTT, clonogenic, and EdU assays were used to assess cell proliferation. Transwell assays were performed to detect cell migration and invasion. Signaling pathways involved in HMGB3 function were identified by RNA sequencing (RNA-seq). MAPK/ERK signaling pathway protein levels were evaluated by western blot.

RESULTS

HMGB3 knockdown inhibited ovarian cancer cell proliferation and metastasis, whereas HMGB3 overexpression facilitated these processes. RNA-seq showed that HMGB3 participates in regulating stem cell pluripotency and the MAPK signaling pathway. We further proved that HMGB3 promotes ovarian cancer stemness, proliferation, and metastasis through activating the MAPK/ERK signaling pathway. In addition, we demonstrated that HMGB3 promotes tumor growth in a xenograft model via MAPK/ERK signaling.

CONCLUSIONS

HMGB3 promotes ovarian cancer malignant phenotypes and stemness through the MAPK/ERK signaling pathway. Targeting HMGB3 is a promising strategy for ovarian cancer treatment that may improve the prognosis of women with this disease. Video Abstract.

LMNB1 deletion in ovarian cancer inhibits the proliferation and metastasis of tumor cells through PI3K/Akt pathway

Ovarian cancer (OC) is a common malignant tumor in gynecology. LMNB1 is an important component of the nuclear skeleton. The expression of LMNB1 in ovarian cancer is significantly higher than that in normal tissues, but its role in tumor still needs comprehensive investigation. In this study, we overexpressed and knocked down LMNB1 in ovarian cancer cells and explore the effect of LMNB1 on the cell proliferation, migration and the underlying mechanism. We analyzed the expression levels of LMNB1 in ovarian cancer and their clinical relevance by using bioinformatics methods, qRT-PCR, Western blot and immunohistochemistry. To state the effect and mechanism of LMNB1 on OC in vitro and in vivo, we performed mouse xenograft studies, CCK8, cloning formation, Edu incorporation, wound healing, transwell and flow cytometry assay in stable LMNB1 knockdown OC cells, following by RNA-seq. Overexpression of LMNB1 indicates the progression of OC. LMNB1 knockdown inhibited the proliferation and migration of OC cells by suppressing the FGF1-mediated PI3K-Akt signaling pathway. Our study shows LMNB1 as a novel prognostic factor and therapeutic target in OC.

PARP inhibitor olaparib induced differential protein expression in cervical cancer cells

PARP inhibitors are a potential class of chemotherapeutic drugs but PARP inhibitor response has not been explored systematically. We lack a specific understanding of the subset of the proteome preferentially modified in various cancers by PARP inhibitors. Implications of PARP inhibitor and PARP1 in cervical cancer treatment and resistance are not fully elucidated. We conducted a mass spectrometry-based proteomic analysis of cervical cancer Hela cells treated with olaparib. We aimed to identify the alteration in the protein signaling pathway induced by PARP inhibitors beyond the DNA damage response pathway. Our data demonstrate a significant reduction in PARP activity and enhanced cell death after olaparib treatment. We further observed articulated proteomic changes with a significant enrichment of proteins in diverse cellular processes. The differentially expressed proteins were predominantly associated with RNA metabolism, mRNA splicing, processing, and RNA binding. Our data also identified proteins that could probably contribute to survival mechanisms resulting in resistance to PARP inhibitors. Hence, we put forth the overview of proteomic changes induced by PARP inhibitor olaparib in cervical cancer cells. This study highlights the significant proteins modified during PARP inhibition and thus could be a probable target for combination therapies with PARP inhibitors in cervical cancer. SIGNIFICANCE.

Advances in small molecule maintenance therapies for high-grade serous ovarian cancer

INTRODUCTION

Ovarian cancer is one of the most lethal gynecological tumors with a lack of effective treatment modalities especially in advanced/recurrent disease. Nevertheless, recently, new small molecules have emerged as an effective approach for the management of ovarian cancer patients, especially in the maintenance setting.

AREAS COVERED

This review summarizes the role of small molecules used in the management of high-grade serous ovarian cancer. The authors performed a critical review of current evidence and ongoing studies. Of note, tyrosine kinase inhibitors (TKIs) and poly(ADP-ribose) polymerase (PARP) inhibitors are the most intriguing medications in this setting.

EXPERT OPINION

Protein-targeted therapies against tumor tissues have progressed significantly in the last years due to an enhanced knowledge of the biological and molecular processes of carcinogenesis. Treatment with small molecules allows the targeting of specific proteins involved in cancer biology. TKIs seem promising but further data are necessary to assess the pros and cons of adopting this treatment modality. PARP inhibitors represent the new standard of care for ovarian cancer patients harboring either a BRCA mutation or with homologous recombination deficiency (HRD). Interestingly, the accumulation of data has highlighted that PARP inhibitors provide benefits even in patients with HR proficient tumors.

Human PARP1 substrates and regulators of its catalytic activity: An updated overview

Poly (ADP-ribose) polymerase 1 (PARP1) is a key DNA damage sensor that is recruited to damaged sites after DNA strand breaks to initiate DNA repair. This is achieved by catalyzing attachment of ADP-ribose moieties, which are donated from NAD⁺, on the amino acid residues of itself or other acceptor proteins. PARP inhibitors (PARPi) that inhibit PARP catalytic activity and induce PARP trapping are commonly used for treating BRCA1/2-deficient breast and ovarian cancers through synergistic lethality. Unfortunately, resistance to PARPi frequently occurs. In this review, we present the novel substrates and regulators of the PARP1-catalyzed poly (ADP-ribosyl)ation (PARylatison) that have been identified in the last 3 years. The overall aim is the presentation of protein interactions of potential therapeutic intervention for overcoming the resistance to PARPi.

Expression, tumor immune infiltration, and prognostic impact of HMGs in gastric cancer

Background

In the past decade, considerable research efforts on gastric cancer (GC) have been expended, however, little advancement has been made owing to the lack of effective biomarkers and treatment options. Herein, we aimed to examine the levels of expression, mutations, and clinical relevance of HMGs in GC to provide sufficient scientific evidence for clinical decision-making and risk management.

Methods

GC samples were obtained from The Cancer Genome Atlas (TCGA). University of California Santa Cruz (UCSC) XENA, Human Protein Atlas (HPA), Gene Expression Profiling Interactive Analysis (GEPIA), Kaplan-Meier Plotter, cBioPortal, GeneMANIA, STRING, LinkedOmics, and DAVID databases were employed. The "ggplot2" package in the R software (×64 3.6.3) was used to thoroughly analyze the effects of HMGs. qRT-PCR was performed to assess HMG levels in GC cell lines.

Results

A total of 375 GC tissues and 32 paraneoplastic tissues were analyzed. The levels of HMGA1, HMGA2, HMGB1, HMGB2, HMGB3, HMGN1, HMGN2, and HMGN4 expression were increased in GC tissues relative to normal gastric tissues. HMGA1, HMGA2, HMGB1, HMGB2, and HMGB3 were highly expressed in GC cell lines. The OS was significantly different in the group showing low expressions of HMGA1, HMGA2, HMGB1, HMGB2, HMGB3, HMGN2, HMGN3, and HMGN5. There was a significant difference in RFS between the groups with low HMGA2, HMGB3, and high HMGN2 expression. The levels of HMGA2, HMGB3, and HMGN1 had a higher accuracy for prediction to distinguish GC from normal tissues (AUC value > 0.9). HMGs were tightly associated with immune infiltration and tumor immune escape and antitumor immunity most likely participates in HMG-mediated oncogenesis in GC. GO and KEGG enrichment analyses showed that HMGs played a vital role in the cell cycle pathway.

Conclusions

Our results strongly suggest a vital role of HMGs in GC. HMGA2 and HMGB3 could be potential markers for prognostic prediction and treatment targets for GC by interrupting the cell cycle pathway. Our findings might provide renewed perspectives for the selection of prognostic biomarkers among HMGs in GC and may contribute to the determination of the optimal strategy for the treatment of these patients.

cAMP-Dependent Signaling and Ovarian Cancer

cAMP-dependent pathway is one of the most significant signaling cascades in healthy and neoplastic ovarian cells. Working through its major effector proteins-PKA and EPAC-it regulates gene expression and many cellular functions. PKA promotes the phosphorylation of cAMP response element-binding protein (CREB) which mediates gene transcription, cell migration, mitochondrial homeostasis, cell proliferation, and death. EPAC, on the other hand, is involved in cell adhesion, binding, differentiation, and interaction between cell junctions. Ovarian cancer growth and metabolism largely depend on changes in the signal processing of the cAMP-PKA-CREB axis, often associated with neoplastic transformation, metastasis, proliferation, and inhibition of apoptosis. In addition, the intracellular level of cAMP also determines the course of other pathways including AKT, ERK, MAPK, and mTOR, that are hypo- or hyperactivated among patients with ovarian neoplasm. With this review, we summarize the current findings on cAMP signaling in the ovary and its association with carcinogenesis, multiplication, metastasis, and survival of cancer cells. Additionally, we indicate that targeting particular stages of cAMP-dependent processes might provide promising therapeutic opportunities for the effective management of patients with ovarian cancer.

Biomarkers beyond BRCA: promising combinatorial treatment strategies in overcoming resistance to PARP inhibitors

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) exploit the concept of synthetic lethality and offer great promise in the treatment of tumors with deficiencies in homologous recombination (HR) repair. PARPi exert antitumor activity by blocking Poly(ADP-ribosyl)ation (PARylation) and trapping PARP1 on damaged DNA. To date, the U.S. Food and Drug Administration (FDA) has approved four PARPi for the treatment of several cancer types including ovarian, breast, pancreatic and prostate cancer. Although patients with HR-deficient tumors benefit from PARPi, majority of tumors ultimately develop acquired resistance to PARPi. Furthermore, even though BRCA1/2 mutations are commonly used as markers of PARPi sensitivity in current clinical practice, not all patients with BRCA1/2 mutations have PARPi-sensitive disease. Thus, there is an urgent need to elucidate the molecular mechanisms of PARPi resistance to support the development of rational effective treatment strategies aimed at overcoming resistance to PARPi, as well as reliable biomarkers to accurately identify patients who will most likely benefit from treatment with PARPi, either as monotherapy or in combination with other agents, so called marker-guided effective therapy (Mget). In this review, we summarize the molecular mechanisms driving the efficacy of and resistance to PARPi as well as emerging therapeutic strategies to overcome PARPi resistance. We also highlight the identification of potential markers to predict PARPi resistance and guide promising PARPi-based combination strategies.

The role of E3 ubiquitin ligase WWP2 and the regulation of PARP1 by ubiquitinated degradation in acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) has been a huge threat for people's health and finding effective target therapy is urgent and important. WWP2, as one of E3 ubiquitin ligase, is involved in many biological processes by specifically binding to substrates. PARP1 plays a role in cell apoptosis and is considered as a therapeutic target of certain cancers. In this study, we firstly found that WWP2 expressed higher in newly diagnosed ALL patients comparing with complete remission (CR) ALL patients and normal control people, and WWP2 in relapse ALL patients expressed higher than normal control people. WWP2 expression was related with the FAB subtype of ALL and the proportion of blast cells in bone marrow blood tested by flow cytometry. We demonstrated knockout WWP2 inhibited the ALL growth and enhanced apoptosis induced by Dox in vitro and vivo for the first time. WWP2 negatively regulated and interacted with PARP1 and WWP2 mechanically degraded PARP1 through polyubiquitin-proteasome pathway in ALL. These findings suggested WWP2 played a role in ALL development as well as growth and apoptosis, and also displayed a regulatory pathway of PARP1, which provided a new potential therapeutic target for the treatment of ALL.

SLOAD: a comprehensive database of cancer-specific synthetic lethal interactions for precision cancer therapy via multi-omics analysis

Synthetic lethality has been widely concerned because of its potential role in cancer treatment, which can be harnessed to selectively kill cancer cells via identifying inactive genes in a specific cancer type and further targeting the corresponding synthetic lethal partners. Herein, to obtain cancer-specific synthetic lethal interactions, we aimed to predict genetic interactions via a pan-cancer analysis from multiple molecular levels using random forest and then develop a user-friendly database. First, based on collected public gene pairs with synthetic lethal interactions, candidate gene pairs were analyzed via integrating multi-omics data, mainly including DNA mutation, copy number variation, methylation and mRNA expression data. Then, integrated features were used to predict cancer-specific synthetic lethal interactions using random forest. Finally, SLOAD (http://www.tmliang.cn/SLOAD) was constructed via integrating these findings, which was a user-friendly database for data searching, browsing, downloading and analyzing. These results can provide candidate cancer-specific synthetic lethal interactions, which will contribute to drug designing in cancer treatment that can promote therapy strategies based on the principle of synthetic lethality.

Database URL http://www.tmliang.cn/SLOAD/