The Significance of Targeting Poly (ADP-Ribose) Polymerase-1 in Pancreatic Cancer for Providing a New Therapeutic Paradigm

PARP1 promotes EGFR-TKI drug-resistance via PI3K/AKT pathway in non-small-cell lung cancer

PURPOSE

Tyrosine kinase inhibitor (TKI) resistance is the main type of drug resistance in lung cancer patients with epidermal growth factor receptor (EGFR) mutations, but its underlying mechanism remains unclear. The purpose of this work was to investigate the mechanism by which PARP1 regulates EGFR-TKI resistance to identify potential targets for combating drug resistance.

METHODS

The GEO databases, TCGA databases, western blot and qPCR studies were used to investigate the expression of PARP1 in lung cancer cells and tissues and its correlation with the prognosis of lung cancer. The expression of PARP1 in lung cancer TKI resistant cell PC9-ER and TKI sensitive cell PC9 was analyzed by qPCR and western blot. After knocking down of PARP1, CCK-8 assays, colony formation, flow cytometry were used to investigate its impact on erlotinib sensitivity, cell survival, cell cycle, and apoptosis. RNA-seq was used to investigate the mechanism by which PARP1 participates in EGFR-TKI resistance, and the results were validated in vitro and in vivo studies.

RESULTS

PARP1 was highly expressed in both lung cancer tissues and cells. Subsequently, increased PARP1 expression was observed in PC9-ER compared with its parental cell line. Knockdown of PARP1 increased erlotinib sensitivity, promoted cell apoptosis, and suppressed cell growth. RNA-seq and previous studies have shown that the PI3K/AKT/mTOR/P70S6K pathway is involved in PARP1-mediated TKI resistance, and these results were confirmed by Western blot in vitro and in vivo.

CONCLUSION

PARP1 may serve as a potential therapeutic target for reversing EGFR-TKI resistance in NSCLC via the PI3K/AKT/mTOR/P70S6K pathway.

Poly (ADP-ribose): A double-edged sword governing cancer cell survival and death

Poly (ADP-ribose) (PAR), a polymer of ADP-ribose, is synthesized by PAR polymerase and is crucial for the survival of cancer cells due to its vital functions in DNA repair and post-translational modifications. Beyond its supportive role, PAR also triggers cancer cell death by excessive accumulation of PAR leading to an energy crisis and parthanatos. This phenomenon underscores the potential of targeting PAR regulation as a novel anticancer strategy, and the rationale would present an engaging topic in the field of anticancer research. Therefore, this editorial provides an overview of the mechanisms determining cancer cell fate, emphasizing the central role of PAR. It further introduces promising methods for modulating PAR concentrations that may pave the way for innovative anticancer therapies.

Moracin D suppresses cell growth and induces apoptosis via targeting the XIAP/PARP1 axis in pancreatic cancer

BACKGROUND

Pancreatic cancer, a tumor with a high metastasis rate and poor prognosis, is among the deadliest human malignancies. Investigating effective drugs for their treatment is imperative. Moracin D, a natural benzofuran compound isolated from Morus alba L., shows anti-inflammation and anti-breast cancer properties and is effective against Alzheimer's disease. However, the effect and mechanism of Moracin D action in pancreatic cancer remain obscure.

PURPOSE

To investigate the function and molecular mechanism of Moracin D action in repressing the malignant progression of pancreatic cancer.

METHODS

Pancreatic cancer cells were treated with Moracin D, and cell proliferation was evaluated by cell counting kit-8 (CCK-8) and immunofluorescence assays. The clonogenicity of pancreatic cancer cells was assessed based on plate colony formation and soft agar assay. Flow cytometry was used to detect cell apoptosis. The expression of proteins related to the apoptosis pathway was determined by Western blot analysis. Moracin D and XIAP were subjected to docking by auto-dock molecular docking analysis. Ubiquitination levels of XIAP and the interaction of XIAP and PARP1 were assessed by co-immunoprecipitation analysis. Moracin D's effects on tumorigenicity were assessed by a tumor xenograft assay.

RESULTS

Moracin D inhibited cell proliferation, induced cell apoptosis, and regulated the protein expression of molecules involved in caspase-dependent apoptosis pathways. Moracin D suppressed clonogenicity and tumorigenesis of pancreatic cancer cells. Mechanistically, XIAP could interact with PARP1 and stabilize PARP1 by controlling its ubiquitination levels. Moracin D diminished the stability of XIAP and decreased the expression of XIAP by promoting proteasome-dependent XIAP degradation, further blocking the XIAP/PARP1 axis and repressing the progression of pancreatic cancer. Moracin D could dramatically improve the chemosensitivity of gemcitabine in pancreatic cancer cells.

CONCLUSION

Moracin D repressed cell growth and tumorigenesis, induced cell apoptosis, and enhanced the chemosensitivity of gemcitabine through the XIAP/PARP1 axis in pancreatic cancer. Moracin D is a potential therapeutic agent or adjuvant for pancreatic cancer.

Palladium‐Catalysed C−C Bond Forming 4‐Cyanophenyl‐nicotinamide Conjugates; Anti‐Pancreatic Cancer Screening on Capan‐1 Cell Line

Pancreatic cancer is the most severe, as a consequence of asymptomatic nature and ineffective therapies among all malignancies. Nicotinamides are effective ring systems in the treatment of pancreatic cancer with their wide range of applications. In the present investigation, nicotinamide and 4‐cyanophenyl ring systems are brought together to obtain greater potency. For the process of investigation, PARP1 protein is targeted and evaluated by docking at the active site to determine the protein‐ligand interaction, revealed the potential with the binding affinity of −9.0 to −11.0 Kcal/mol to inhibit the poly ADP‐ribose polymerase 1 (PARP1) pathway. The MTT‐assay assessment of a synthesized series has been performed against Capan‐1 pancreatic cancer cell line. The nicotinamide compounds demonstrated a significant inhibitory effect over Capan‐1 cell line, and 6‐(4‐cyanophenyl)‐N‐(3‐phenylpropyl)nicotinamide exhibited as a potential lead for the development of novel chemotherapeutics against pancreatic cancer.

Accumulation of poly (adenosine diphosphate-ribose) by sustained supply of calcium inducing mitochondrial stress in pancreatic cancer cells

BACKGROUND

The biochemical phenomenon defined as poly adenosine diphosphate (ADP)-ribosylation (PARylation) is essential for the progression of pancreatic cancer. However, the excessive accumulation of poly ADP-ribose (PAR) induces apoptosis-inducing factor (AIF) release from mitochondria and energy deprivation resulting in the caspase-independent death of cancer cells.

AIM

To investigate whether sustained calcium supply could induce an anticancer effect on pancreatic cancer by PAR accumulation.

METHODS

Two pancreatic cancer cell lines, AsPC-1 and CFPAC-1 were used for the study. Calcium influx and mitochondrial reactive oxygen species (ROS) were observed by fluorescence staining. Changes in enzyme levels, as well as PAR accumulation and energy metabolism, were measured using assay kits. AIF-dependent cell death was investigated followed by confirming in vivo anticancer effects by sustained calcium administration.

RESULTS

Mitochondrial ROS levels were elevated with increasing calcium influx into pancreatic cancer cells. Then, excess PAR accumulation, decreased PAR glycohydrolase and ADP-ribosyl hydrolase 3 levels, and energy deprivation were observed. In vitro and in vivo antitumor effects were confirmed to accompany elevated AIF levels.

CONCLUSION

This study visualized the potential anticancer effects of excessive PAR accumulation by sustained calcium supply on pancreatic cancer, however elucidating a clear mode of action remains a challenge, and it should be accompanied by further studies to assess its potential for clinical application.