{
  "abstract": "Background: Andrographolide (AG), a diterpenoid lactone and a major constituent of Andrographis paniculata, has shown promising antiproliferative effect on diverse cancer cell lines, including head and neck cancer. However, a significant anti-proliferative effect is observed only at high micromolar concentrations. Further, AG has been shown to have poor oral bioavailability. Therefore, it is essential to consider mechanism-based combinations that could synergistically enhance the therapeutic potential of this compound so that efficacy can be achieved in concentrations that are systemically achievable. Objective: The present study is aimed to evaluate the anticancer effects and associated molecular alterations of an AG and Chk1/2 inhibitor combination in head and neck squamous cell carcinoma (CAL-33) cells since the earlier studies have suggested ATM/ATR/Chk1/2-mediated activation of DNA damage checkpoints. Methods: Normal FHs74int cells and HNSCC cells (CAL-33 and FaDu) were used to assess cell proliferation and cell death. Cell cycle distribution and apoptosis were analyzed by flow cytometry and Acridine orange/EtBr, respectively, in CAL-33 cells. DNA damage in CAL-33 and FaDu cells was assessed by comet assay. Changes in the expression of proteins implicated in apoptosis, cell cycle progression, and DNA damage signaling were examined using Western blotting. Results: While AG did not show any significant changes in the growth or cell death of normal FHs74int cells, it strongly inhibited proliferation of HNSCC cells, concomitant with G2/M arrest and apoptosis. AG and AZD7762 showed an IC50 of 2.743 μM and 0.02600 μM, respectively, on cell proliferation in CAL-33 cells. Furthermore, AG caused an accumulation of intracellular ROS, which was inhibited by treatment with N-acetylcysteine. Chk1, Chk2 and γH2AX phosphorylation were induced in a dose-dependent manner by treatment with AG. The combination of AG with Chk1/2 inhibitor AZD7762 showed a synergistic effect in inhibiting cell proliferation with a CI of 0.4 through inhibition of DNA repair and premature mitotic entry, ultimately resulting in programmed cell death. Conclusions: These findings provide evidence that AG selectively targets DNA damage and repair in HNSCC CAL-33 cells via cell cycle arrest and apoptosis. Further, the anticancer potential of AG can be significantly enhanced by combination with the Chk1/2 inhibitor AZD7762, preventing repair of AG-induced DNA damage and amplifying checkpoint stress responses, resulting in enhanced apoptotic cell death. Together, these findings support the therapeutic potential of AG and highlight checkpoint kinase inhibition as a rational combination strategy for HNSCC treatment.",
  "abstract_shown": true,
  "affiliations": [
    "School of Biotechnology, Gautam Buddha University, Greater Noida 201312, UP, India.",
    "Cancer Biology Laboratory, Department of Life Sciences, Central University of Gujarat, Gandhinagar 382030, GJ, India.",
    "Cancer Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India.",
    "Center for Experimental Therapeutics, Oregon Health and Science University, Portland, OR 97239, USA."
  ],
  "article_type": "research article",
  "arxiv": null,
  "author_total": 5,
  "authors": [
    {
      "affs": [
        0
      ],
      "name": "Sakshi Singh"
    },
    {
      "affs": [
        1
      ],
      "name": "Anitha Kartha"
    },
    {
      "affs": [
        2
      ],
      "name": "Aishwarya Jaiswal"
    },
    {
      "affs": [
        3
      ],
      "name": "Dhanir Tailor",
      "orcid": "0000-0002-8138-4469"
    },
    {
      "affs": [
        0
      ],
      "name": "Sivanandhan Dhanalakshmi"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/aqtcs1dq4vpby.bib",
  "cited_by": 0,
  "doi": "10.3390/cancers18193199",
  "fulltext_url": "https://europepmc.org/articles/PMC13664140",
  "id": "aqtcs1dq4vpby",
  "issns": [
    "2072-6694"
  ],
  "landing_url": "https://europepmc.org/article/MED/42882893",
  "language": "eng",
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2707|Andrographolide Research and Applications"
    ]
  ],
  "openalex": "W7220422641",
  "pdf_url": "https://europepmc.org/articles/PMC13664140?pdf=render",
  "pmcid": "PMC13664140",
  "pmid": "42882893",
  "published": "2026-10-03",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/aqtcs1dq4vpby.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:19:00Z",
      "native_id": "MED:42882893",
      "source": "europepmc",
      "url": "https://europepmc.org/article/MED/42882893"
    },
    {
      "first_seen": "2026-10-30T12:19:58Z",
      "native_id": "10.3390/cancers18193199",
      "source": "crossref",
      "url": "https://www.mdpi.com/2072-6694/18/19/3199"
    }
  ],
  "subjects": [
    {
      "field": "medicine",
      "origin": "issn:2072-6694",
      "subfield": "oncology"
    }
  ],
  "title": "Chk1/2 Inhibition by AZD7762 Enhances Andrographolide-Induced DNA Damage, Impairs DNA Repair, and Promotes Apoptosis in Head and Neck Squamous Cell Carcinoma CAL-33 Cells.",
  "title_text": "Chk1/2 Inhibition by AZD7762 Enhances Andrographolide-Induced DNA Damage, Impairs DNA Repair, and Promotes Apoptosis in Head and Neck Squamous Cell Carcinoma CAL-33 Cells.",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:19:58Z",
  "url": "https://research.draconitic.com/paper/aqtcs1dq4vpby",
  "venue": "Cancers",
  "versions": []
}