Olaparib-mediated enhancement of 5-fluorouracil cytotoxicity in mismatch repair deficient colorectal cancer cells

DRSPRING: Graph convolutional network (GCN)-Based drug synergy prediction utilizing drug-induced gene expression profile

Great efforts have been made over the years to identify novel drug pairs with synergistic effects. Although numerous computational approaches have been proposed to analyze diverse types of biological big data, the pharmacogenomic profiles, presumably the most direct proxy of drug effects, have been rarely used due to the data sparsity problem. In this study, we developed a composite deep-learning-based model that predicts the drug synergy effect utilizing pharmacogenomic profiles as well as molecular properties. Graph convolutional network (GCN) was used to represent and integrate the chemical structure, genetic interactions, drug-target information, and gene expression profiles of cell lines. Insufficient amount of pharmacogenomic data, i.e., drug-induced expression profiles from the LINCS project, was resolved by augmenting the data with the predicted profiles. Our method learned and predicted the Loewe synergy score in the DrugComb database and achieved a better or comparable performance compared to other published methods in a benchmark test. We also investigated contribution of various input features, which highlighted the value of basal gene expression and pharmacogenomic profiles of each cell line. Importantly, DRSPRING (DRug Synergy PRediction by INtegrated GCN) can be applied to any drug pairs and any cell lines, greatly expanding its applicability compared to previous methods.

PARP Inhibitors in Colorectal Malignancies: A 2023 Update

BACKGROUND

Colorectal carcinoma (CRC) is one of the most common malignancies in the Western world, and metastatic disease is associated with a dismal prognosis. Poly-ADpribose polymerase (PARP) inhibitors gain increasing attention in the field of medical oncology, as they lead to synthetic lethality in malignancies with preexisting alterations in the DNA damage repair (DDR) pathway. As those alterations are frequently seen in CRC, a targeted approach through PARP inhibitors is expected to benefit these patients, both alone and in combination with other agents like chemotherapy, immunotherapy, antiangiogenics, and radiation.

OBJECTIVE

This review article aims to better clarify the role of PARP inhibitors as a treatment option in patients with metastatic CRC with alterations in the DDR pathway.

METHODS

We used the PubMed database to retrieve journal articles and the inclusion criteria were all human studies that illustrated the effective role of PARP inhibitors in patients with metastatic CRC with homologous repair deficiency (HRD) and the correct line of therapy.

RESULTS

Current evidence supports the utilization of PARP inhibitors in CRC subgroups, as monotherapy and in combination with other agents. Up to now, data are insufficient to support a formal indication, and further research is needed.

CONCLUSION

Efforts to precisely define the homologous repair deficiency (HRD) in CRC - and eventually the subgroup of patients that are expected to benefit the most - are also underway.

Chitosan Thermosensitive Hydrogel Based on DNA Damage Repair Inhibition and Mild Photothermal Therapy for Enhanced Antitumor Treatment

The DNA damage repair of tumor cells limits the effect of photothermal therapy (PTT), and high temperatures induced by PTT can damage adjacent normal tissues. To overcome these limitations, we developed a novel composite hydrogel (OLA-Au-Gel) based on chitosan (CS) and β-glycerophosphate (β-GP), which encapsulated olaparib-liposomes (OLA-lips) and CS-capped gold nanoparticles (CS-AuNPs). OLA-Au-Gel achieved the combination of mild PTT (mPTT) by CS-AuNPs and tumor DNA damage repair inhibition by OLA. The hydrogel showed good biocompatibility, injectability, and photothermal response. Under near-infrared laser irradiation, OLA-Au-Gel inhibited the proliferation of tumor cells, induced the generation of reactive oxygen species in vitro, and effectively inhibited the growth of breast tumors in vivo. OLA-Au-Gel shows a promising application prospect for inhibiting tumor development and improving the antitumor effect. Collectively, we propose a novel strategy for enhanced antitumor therapy based on the combination of mPTT and DNA damage repair inhibition.

Biomarkers for chemotherapy and drug resistance in the mismatch repair pathway

Drugs targeting DNA repair have developed rapidly in cancer therapy, and numerous inhibitors have already been utilized in preclinical and clinical stages. To optimize the selection of patients for treatment, it is essential to discover biomarkers to anticipate chemotherapy response. The DNA mismatch repair (MMR) pathway is closely correlated with cancer susceptibility and plays an important role in the occurrence and development of cancers. Here, we give a concise introduction of the MMR genes and focus on the potential biomarkers of chemotherapeutic response and resistance. It has been clarified that the status of MMR may affect the outcome of chemotherapy. However, the specific underlying mechanisms as well as contradictory results continue to raise considerable controversy and concern. In this review, we summarize the current literature to provide a general overview.

Research progress of traditional Chinese medicine as sensitizer in reversing chemoresistance of colorectal cancer

In recent years, the incidences and mortalities from colorectal cancer (CRC) have been increasing; therefore, there is an urgent need to discover newer drugs that enhance drug sensitivity and reverse drug tolerance in CRC treatment. With this view, the current study focuses on understanding the mechanism of CRC chemoresistance to the drug as well as exploring the potential of different traditional Chinese medicine (TCM) in restoring the sensitivity of CRC to chemotherapeutic drugs. Moreover, the mechanism involved in restoring sensitivity, such as by acting on the target of traditional chemical drugs, assisting drug activation, increasing intracellular accumulation of anticancer drugs, improving tumor microenvironment, relieving immunosuppression, and erasing reversible modification like methylation, have been thoroughly discussed. Furthermore, the effect of TCM along with anticancer drugs in reducing toxicity, increasing efficiency, mediating new ways of cell death, and effectively blocking the drug resistance mechanism has been studied. We aimed to explore the potential of TCM as a sensitizer of anti-CRC drugs for the development of a new natural, less-toxic, and highly effective sensitizer to CRC chemoresistance.

Colorectal cancer organoid models uncover oxaliplatin-resistant mechanisms at single cell resolution

PURPOSE

Oxaliplatin-based chemotherapy is a standard treatment for advanced colorectal cancer (CRC) patients. However, chemoresistance-induced resistance is an essential cause for mortality. Therefore, it is necessary to study the mechanism of drug resistance in CRC.

METHODS

Here, we established two strains of patient-derived organoids (PDOs) selected from oxaliplatin-resistant and treatment-naïve CRC patients. To dissect the drug-resistant mechanisms, these CRC-PDOs were subjected to single-cell RNA sequencing (scRNA-Seq).

RESULTS

We found that the drug sensitivity test outcome from these organoids subjected to oxaliplatin and 5-FU exposure was consistent with the clinic readout. CRC-PDOs well recapitulated the morphology and histology of their parental biopsies based on HE and IHC staining of pathological biomarkers. The scRNA-Seq data filtered drug-resistant cell populations and related signaling pathways (e.g. oxidative phosphorylation and ATP metabolic process). The data also revealed several putative drug resistant-driven genes (STMN1, VEGFA and NDRG1) and transcription factors (E2F1, BRCA1, MYBL2, CDX2 and CDX1).

CONCLUSION

We generated an oxaliplatin-resistant CRC organoid model that was employed to provide potential therapeutic targets for treating CRC patients exhibiting oxaliplatin-resistance.

Identification of an m6A-Related Long Noncoding RNA Risk Model for Predicting Prognosis and Directing Treatments in Patients With Colon Adenocarcinoma

N6-methyladenosine (m6A) and lncRNAs have been implicated in the development of colon cancer, including tumorigenesis, migration, and invasion. However, the specific effect of m6A regulators on lncRNAs is not clear, and m6A-related lncRNAs may be new prognostic biomarkers and may help direct treatment and medication. We identified 29 prognostic m6A-related lncRNAs and constructed a risk model using 12 lncRNAs. The model was an independent prognostic factor and could accurately predict the prognosis. A stable and robust nomogram that combined the model and pathologic stage was constructed. A total of 2,424 differentially expressed genes (DEGs) were identified based on the model. Functional analysis of the DEGs showed that they were associated with tumor progression, helping investigate the underlying biological functions and signaling pathways of the risk model. In addition, the low-risk group based on the risk model had more sensitivity to afatinib, metformin, and GW.441756, and patients with low risk would more likely respond to immunotherapy. Moreover, patients with higher risk were more sensitive to olaparib, bexarotene, and doxorubicin.

Case Report: Combination of Olaparib With Chemotherapy in a Patient With ATM-Deficient Colorectal Cancer

Poly-ADP ribose polymerase (PARP) inhibitors are constantly increasing in their indications for use as anti-cancer treatment in various neoplasms, the majority of which are linked with BRCA deficiency. Preclinical data support the investigation of PARP inhibitors in other neoplasms exhibiting “BRCAness” or homologous recombination deficiency (HRD) as monotherapy as well as in combination with chemotherapy. With the current report we present the case of a heavily pretreated 55-year-old male patient diagnosed with stage IV ATM-deficient CRC, who was effectively treated with an off-label olaparib-irinotecan combination after exhaustion of all available treatment choices; furthermore, we discuss the existing data providing evidence for the use of PARP inhibitors in ATM-deficient CRC and encourage the implementation of next-generation sequencing (NGS) in patients with no other available treatment options.

Analyzing the Opportunities to Target DNA Double-Strand Breaks Repair and Replicative Stress Responses to Improve Therapeutic Index of Colorectal Cancer

Despite the ample improvements of CRC molecular landscape, the therapeutic options still rely on conventional chemotherapy-based regimens for early disease, and few targeted agents are recommended for clinical use in the metastatic setting. Moreover, the impact of cytotoxic, targeted agents, and immunotherapy combinations in the metastatic scenario is not fully satisfactory, especially the outcomes for patients who develop resistance to these treatments need to be improved. Here, we examine the opportunity to consider therapeutic agents targeting DNA repair and DNA replication stress response as strategies to exploit genetic or functional defects in the DNA damage response (DDR) pathways through synthetic lethal mechanisms, still not explored in CRC. These include the multiple actors involved in the repair of DNA double-strand breaks (DSBs) through homologous recombination (HR), classical non-homologous end joining (NHEJ), and microhomology-mediated end-joining (MMEJ), inhibitors of the base excision repair (BER) protein poly (ADP-ribose) polymerase (PARP), as well as inhibitors of the DNA damage kinases ataxia-telangiectasia and Rad3 related (ATR), CHK1, WEE1, and ataxia-telangiectasia mutated (ATM). We also review the biomarkers that guide the use of these agents, and current clinical trials with targeted DDR therapies.