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The Oncologist Jun 2024The activity of PARP inhibitors (PARPi) in patients with homologous recombination repair (HRR) mutations and metastatic castration-resistant prostate cancer has been...
TRIUMPH: phase II trial of rucaparib monotherapy in patients with metastatic hormone-sensitive prostate cancer harboring germline homologous recombination repair gene mutations.
BACKGROUND
The activity of PARP inhibitors (PARPi) in patients with homologous recombination repair (HRR) mutations and metastatic castration-resistant prostate cancer has been established. We hypothesized that the benefit of PARPi can be maintained in the absence of androgen deprivation therapy (ADT) in an HRR-mutated population. We report the results of a phase II clinical trial of rucaparib monotherapy in patients with metastatic hormone-sensitive prostate cancer (mHSPC).
METHODS
This was a multi-center, single-arm phase II trial (NCT03413995) for patients with asymptomatic, mHSPC. Patients were required to have a pathogenic germline mutation in an HRR gene for eligibility. All patients received rucaparib 600 mg by mouth twice daily, without androgen deprivation. The primary endpoint was a confirmed PSA50 response rate.
RESULTS
Twelve patients were enrolled, 7 with a BRCA1/2 mutation and 5 with a CHEK2 mutation. The confirmed PSA50 response rate to rucaparib was 41.7% (N = 5/12, 95% CI: 15.2-72.3%, one-sided P = .81 against the 50% null), which did not meet the pre-specified efficacy boundary to enroll additional patients. In patients with measurable disease, the objective response rate was 60% (N = 3/5), all with a BRCA2 mutation. The median radiographic progression-free survival on rucaparib was estimated at 12.0 months (95% CI: 8.0-NR months). The majority of adverse events were grade ≤2, and expected.
CONCLUSION
Rucaparib can induce clinical responses in a biomarker-selected metastatic prostate cancer population without concurrent ADT. However, the pre-specified efficacy threshold was not met, and enrolment was truncated. Although durable responses were observed in a subset of patients, further study of PARPi treatment without ADT in mHSPC is unlikely to change clinical practice.
PubMed: 38885246
DOI: 10.1093/oncolo/oyae120 -
Therapeutic Advances in Medical Oncology 2024Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) have transformed the treatment of ovarian cancer, particularly benefiting patients whose tumors harbor genomic... (Review)
Review
Poly(ADP-ribose) polymerase (PARP) inhibitors (PARPis) have transformed the treatment of ovarian cancer, particularly benefiting patients whose tumors harbor genomic events that result in impaired homologous recombination (HR) repair. The use of PARPi over recent years has expanded to include subpopulations of patients with breast, pancreatic, and prostate cancers. Their potential to benefit patients with non-ovarian gynecologic cancers is being recognized. This review examines the underlying biological rationale for exploring PARPi in non-ovarian gynecologic cancers. We consider the clinical data and place this in the context of the current treatment landscape. We review the development of PARPi strategies for treating patients with endometrial, cervical, uterine leiomyosarcoma, and vulvar cancers. Furthermore, we discuss future directions and the importance of understanding HR deficiency in the context of each cancer type.
PubMed: 38882441
DOI: 10.1177/17588359241255174 -
Cancer Letters Jun 2024Platinum-based chemotherapy causes genetic damage and induces apoptosis in ovarian cancer cells. Enhancing the ability to resist platinum drug-induced DNA damage and...
Platinum-based chemotherapy causes genetic damage and induces apoptosis in ovarian cancer cells. Enhancing the ability to resist platinum drug-induced DNA damage and apoptotic stress is critical for tumor cells to acquire drug resistance. Here, we found that Y-box binding protein 1 (YBX1) was highly expressed in cisplatin-resistant patient-derived organoids (PDOs) and was a crucial gene for alleviating platinum-induced stress and maintaining drug resistance characteristics in ovarian cancer cells. Mechanistically, YBX1 recognized m5C modifications in CHD3 mRNA and maintained mRNA stability by recruiting PABPC1 protein. This regulatory process enhanced chromatin accessibility and improved the efficiency of homologous recombination (HR) repair, facilitating tumor cells to withstand platinum-induced apoptotic stress. In addition, SU056, an inhibitor of YBX1, exhibited the potential to reverse platinum resistance in subcutaneous and PDO orthotopic xenograft models. In conclusion, YBX1 is critical for ovarian cancer cells to alleviate the platinum-induced stress and may be a potential target for reversing drug-resistant therapies.
PubMed: 38880223
DOI: 10.1016/j.canlet.2024.217064 -
Mutation Research Jun 2024Homologous recombination (HR) is essential for repair of DNA double-strand breaks (DSBs) and restart of stalled or collapsed replication forks. Most cancers are...
Homologous recombination (HR) is essential for repair of DNA double-strand breaks (DSBs) and restart of stalled or collapsed replication forks. Most cancers are characterized by mutations in components of the DSB repair pathways. Redundant DSB repair pathways exist in eukaryotes from yeast to humans and recent evidence has shown that complete loss of HR function appears to be lethal. Recent evidence has also shown that cancer cells with mutations in one DSB repair pathway can be killed by inhibiting one or more parallel pathways, a strategy that is currently aggressively explored as a cancer therapy. KDM4B is a histone demethylase with pleiotropic functions, which participates in preparing DSBs for repair by contributing to chromatin remodeling. In this report we carried out a pan-cancer analysis of KDM4B mutations with the goal of understanding their distribution and interaction with other DSB genes. We find that although KDM4B mutations co-occur with DSB repair genes, most KDM4B mutations are not drivers or pathogenic. A sequence conservation analysis from yeast to humans shows that highly conserved residues are resistant to mutation. Finally, all mutations occur in a heterozygous state. A single mutation, R986L, was predicted to significantly affect protein structure using computational modeling. This analysis suggests that KDM4B makes contributions to DSB repair but is not a key player.
PubMed: 38878505
DOI: 10.1016/j.mrfmmm.2024.111866 -
Cell & Bioscience Jun 2024N6-methyladenosine (mA) methylation is a prevalent RNA modification implicated in various diseases. However, its role in intervertebral disc degeneration (IDD), a common...
BACKGROUND
N6-methyladenosine (mA) methylation is a prevalent RNA modification implicated in various diseases. However, its role in intervertebral disc degeneration (IDD), a common cause of low back pain, remains unclear.
RESULTS
In this investigation, we explored the involvement of mA demethylation in the pathogenesis of IDD. Our findings revealed that ALKBH5 (alkylated DNA repair protein AlkB homolog 5), an mA demethylase, exhibited upregulation in degenerative discs upon mild inflammatory stimulation. ALKBH5 facilitated mA demethylation within the three prime untranslated region (3'-UTR) of Runx2 mRNA, consequently enhancing its mRNA stability in a YTHDF1 (YTH N6-methyladenosine RNA binding protein F1)-dependent manner. The subsequent elevation in Runx2 expression instigated the upregulation of ADAMTSs and MMPs, pivotal proteases implicated in extracellular matrix (ECM) degradation and IDD progression. In murine models, subcutaneous administration of recombinant Runx2 protein proximal to the lumbar disc in mice elicited complete degradation of intervertebral discs (IVDs). Injection of recombinant MMP1a and ADAMTS10 proteins individually induced mild to moderate degeneration of the IVDs, while co-administration of MMP1a and ADAMTS10 resulted in moderate to severe degeneration. Notably, concurrent injection of the Runx2 inhibitor CADD522 with recombinant Runx2 protein did not result in IVD degeneration in mice. Furthermore, genetic knockout of ALKBH5 and overexpression of YTHDF1 in mice, along with lipopolysaccharide (LPS) treatment to induce inflammation, did not alter the expression of Runx2, MMPs, and ADAMTSs, and no degeneration of the IVDs was observed.
CONCLUSION
Our study elucidates the role of ALKBH5-mediated mA demethylation of Runx2 mRNA in activating MMPs and ADAMTSs, thereby facilitating ECM degradation and promoting the occurrence of IDD. Our findings suggest that targeting the ALKBH5/Runx2/MMPs/ADAMTSs axis may represent a promising therapeutic strategy for preventing IDD.
PubMed: 38877576
DOI: 10.1186/s13578-024-01264-y -
Neoplasia (New York, N.Y.) Jun 2024Increased mutational burden and EBV load have been revealed from normal tissues to Epstein-Barr virus (EBV)-associated gastric carcinomas (EBVaGCs). BPLF1, encoded by...
Increased mutational burden and EBV load have been revealed from normal tissues to Epstein-Barr virus (EBV)-associated gastric carcinomas (EBVaGCs). BPLF1, encoded by EBV, is a lytic cycle protein with deubiquitinating activity has been found to participate in disrupting repair of DNA damage. We first confirmed that BPLF1 gene in gastric cancer (GC) significantly increased the DNA double strand breaks (DSBs). Ubiquitination mass spectrometry identified histones as BPLF1 interactors and potential substrates, and co-immunoprecipitation and in vitro experiments verified that BPLF1 regulates H2Bub by targeting Rad6. Over-expressing Rad6 restored H2Bub but partially reduced γ-H2AX, suggesting that other downstream DNA repair processes were affected. mRNA expression of BRCA2 were significantly down-regulated by next-generation sequencing after over-expression of BPLF1, and over-expression of p65 facilitated the repair of DSBs. We demonstrated BPLF1 may lead to the accumulation of DSBs by two pathways, reducing H2B ubiquitination (H2Bub) and blocking homologous recombination which may provide new ideas for the treatment of gastric cancer.
PubMed: 38875930
DOI: 10.1016/j.neo.2024.101012 -
Regenerative Therapy Dec 2024The effective promotion of wound healing poses a substantial challenge for clinical treatment. Despite evidence supporting the role of extracellular vesicles (EVs) in...
Multifunctional type lll recombinant human collagen incorporated sodium alginate hydrogel with sustained release of extra cellular vehicles for wound healing multimodal therapy in diabetic mice.
The effective promotion of wound healing poses a substantial challenge for clinical treatment. Despite evidence supporting the role of extracellular vesicles (EVs) in this process, their therapeutic potential is currently restrict by challenges in targeting and maintaining them. The manufacturing process for rhCol III, or recombinant human collagen III, is stable, and the rejection rate is low. We used a cross-linking method to prepare a rhCol III incorporated sodium alginate (SA) hydrogel, which enabled to accomplish an EV sustained release that was site-specific. Cell viability through MTT assay, proliferation and ROS generation were performed with MC3T3-E1cell lines. In addition, diabetic wounds are characterised by an environment of hyper-inflammation and elevated oxidative stress. The rhCol III/SA-EVs hydrogel, which is a delivery vehicle with anti-inflammatory and antioxidant characteristics, promotes wound healing in this setting. The effectiveness of the created wound dressing on a diabetic wound model was examined in this study. After 21 days of treatment, the wound dressing significantly (p < 0.05) expedited wound healing compared to the control group, and wound closure was approximately 95% without any negative systemic reactions.
PubMed: 38873636
DOI: 10.1016/j.reth.2024.03.010 -
Cell Death Discovery Jun 2024Ionising radiation (IR) is widely used in cancer treatment, including for head and neck squamous cell carcinoma (HNSCC), where it induces significant DNA damage leading...
Ionising radiation (IR) is widely used in cancer treatment, including for head and neck squamous cell carcinoma (HNSCC), where it induces significant DNA damage leading ultimately to tumour cell death. Among these lesions, DNA double strand breaks (DSBs) are the most threatening lesion to cell survival. The two main repair mechanisms that detect and repair DSBs are non-homologous end joining (NHEJ) and homologous recombination (HR). Among these pathways, the protein kinases ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3-related (ATR) and the DNA dependent protein kinase catalytic subunit (DNA-Pkcs) play key roles in the sensing of the DSB and subsequent coordination of the downstream repair events. Consequently, targeting these kinases with potent and specific inhibitors is considered an approach to enhance the radiosensitivity of tumour cells. Here, we have investigated the impact of inhibition of ATM, ATR and DNA-Pkcs on the survival and growth of six radioresistant HPV-negative HNSCC cell lines in combination with either X-ray irradiation or proton beam therapy, and confirmed the mechanistic pathway leading to cell radiosensitisation. Using inhibitors targeting ATM (AZD1390), ATR (AZD6738) and DNA-Pkcs (AZD7648), we observed that this led to significantly decreased clonogenic survival of HNSCC cell lines following both X-ray and proton irradiation. Radiosensitisation of HNSCC cells grown as 3D spheroids was also observed, particularly following ATM and DNA-Pkcs inhibition. We confirmed that the inhibitors in combination with X-rays and protons led to DSB persistence, and increased micronuclei formation. Cumulatively, our data suggest that targeting DSB repair, particularly via ATM and DNA-Pkcs inhibition, can exacerbate the impact of ionising radiation in sensitising HNSCC cell models.
PubMed: 38866739
DOI: 10.1038/s41420-024-02059-3 -
Biomedicine & Pharmacotherapy =... Jul 2024DNA repair allows the survival of cancer cells. Therefore, the development of DNA repair inhibitors is a critical need for sensitizing cancers to chemoradiation. Sae2...
BACKGROUND
DNA repair allows the survival of cancer cells. Therefore, the development of DNA repair inhibitors is a critical need for sensitizing cancers to chemoradiation. Sae2 has specific functions in initiating DNA end resection, as well as coordinating cell cycle checkpoints, and it also greatly interacts with the DDR at different levels.
RESULTS
In this study, we demonstrated that corylin, a potential sensitizer, causes deficiencies in DNA repair and DNA damage checkpoints in yeast cells. More specifically, corylin increases DNA damage sensitivity through the Sae2-dependent pathway and impairs the activation of Mec1-Ddc2, Rad53-p and γ-H2A. In breast cancer cells, corylin increases apoptosis and reduces proliferation following Dox treatment by inhibiting CtIP. Xenograft assays showed that treatment with corylin combined with Dox significantly reduced tumor growth in vivo.
CONCLUSIONS
Our findings herein delineate the mechanisms of action of corylin in regulating DNA repair and indicate that corylin has potential long-term clinical utility as a DDR inhibitor.
Topics: DNA Damage; Humans; Animals; DNA Repair; Homologous Recombination; Xenograft Model Antitumor Assays; Female; Mice, Nude; Cell Line, Tumor; Apoptosis; Cell Proliferation; Saccharomyces cerevisiae; Doxorubicin; Mice; Mice, Inbred BALB C; Saccharomyces cerevisiae Proteins
PubMed: 38865847
DOI: 10.1016/j.biopha.2024.116864 -
MBio Jun 2024Parasites of the genus pose a global health threat with limited treatment options. New drugs are urgently needed, and genomic screens have the potential to accelerate...
Parasites of the genus pose a global health threat with limited treatment options. New drugs are urgently needed, and genomic screens have the potential to accelerate target discovery, mode of action, and resistance mechanisms against these new drugs. We describe here our effort in developing a genome-wide CRISPR-Cas9 screen in , an organism lacking a functional nonhomologous end joining system that must rely on microhomology-mediated end joining, single-strand annealing, or homologous recombination for repairing Cas9-induced double-stranded DNA breaks. A new vector for cloning and expressing single guide RNAs (sgRNAs) was designed and proven to be effective in a small pilot project while enriching specific sgRNAs during drug selection. We then developed a whole-genome library of 49,754 sgRNAs, targeting all the genes of . This library was transfected in expressing Cas9, and these cells were selected for resistance to two antileishmanials, miltefosine and amphotericin B. The sgRNAs the most enriched in the miltefosine screen targeted the miltefosine transporter gene, but sgRNAs targeting genes coding for a RING-variant protein and a transmembrane protein were also enriched. The sgRNAs the most enriched by amphotericin B targeted the sterol 24 C methyltransferase genes and a hypothetical gene. Through gene disruption experiments, we proved that loss of function of these genes was associated with resistance. This study describes the feasibility of carrying out whole-genome CRISPR-Cas9 screens in provided that a strong selective pressure is applied. Such a screen can be used for accelerating the development of urgently needed antileishmanial drugs.IMPORTANCELeishmaniasis, a global health threat, lacks adequate treatment options and drug resistance exacerbates the challenge. This study introduces a CRISPR-Cas9 screening approach in , unraveling mechanisms of drug resistance at a genome-wide scale. Our screen was applied against two main antileishmanial drugs, and guides were enriched upon drug selection. These guides targeted known and new targets, hence validating the use of this screen against . This strategy provides a powerful tool to expedite drug discovery as well as potential therapeutic targets against this neglected tropical disease.
PubMed: 38864609
DOI: 10.1128/mbio.00477-24