Tier 2 — strong

SIRT6 Widely Regulates Aging, Immunity, and Cancer

Li Y, Jin J, Wang Y
Frontiers in Oncology 2022 Volume 12, article 861334

Bibliography

DOI
10.3389/fonc.2022.861334
PubMed
PMID 35463332
PubMed Central
PMC9019339
Funding
Supported in part by the National Natural Science Foundation of China (No. 21977121 to YW); and in part by the Direction Project Cultivation Fund, Institute of Immunology and the CAS Key Laboratory of Innate Immunity and Chronic Disease (2020) and University of Science and Technology of China (2021), both to YW.
Competing interests
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Study snapshot

DesignNarrative review of biochemistry, cell biology, animal, and clinical evidence.
ModelReview scope: SIRT6 substrates and enzymatic activities (deacetylation, defatty-acylation, mono-ADP-ribosylation); anti-ageing mechanisms (DNA repair, telomere maintenance, glucose/NAD+ metabolism, SASP regulation); immune regulation in macrophages, T cells, NK cells, DCs, neutrophils, and B cells; cancer regulation across melanoma, breast, lung, pancreatic, liver, prostate, colon, ovarian, blood, osteosarcoma, papillary thyroid, bladder, nasopharyngeal, and glioma.
SampleApproximately 133 primary references catalogued across three regulatory axes.
InterventionNot applicable — literature synthesis.
DurationNot applicable — literature synthesis.
EndpointsEnzymatic characterisation of SIRT6 (deacetylation, defatty-acylation, mono-ADP-ribosylation); SIRT6 substrates and PTM targets in ageing; SIRT6 substrates and PTM targets in immunity; SIRT6 substrates and PTM targets in cancer; Direction of SIRT6 effect (oncogene vs tumour suppressor) by cancer type and stage.

What the study showed, in plain terms

This is a review, not a new experiment. Three researchers at the University of Science and Technology of China pulled together roughly 130 primary studies on SIRT6 and mapped what the enzyme actually does across three domains: ageing, the immune system, and cancer.

On ageing, the review consolidates what SIRT6 does at the molecular level to slow cellular decline. It removes acetyl tags from histones (particularly H3K9, H3K18, and H3K56). It attaches ADP-ribose to PARP1 to sharpen DNA damage repair. It maintains telomere structure. It supports gluconeogenesis and NAD+ balance in old age. And it dampens the inflammatory secretions that senescent cells release into surrounding tissue.

On immunity, the picture is more mixed. In most cell types SIRT6 dampens inflammation — pushing macrophages toward the anti-inflammatory M2 state, calming NF-κB signalling, suppressing Th2 airway inflammation, and reducing joint destruction in arthritis models. But in dendritic cells and pancreatic cells it enhances TNF-α release and can drive inflammatory disease. The review's honest conclusion is that SIRT6 is a complex immune regulator, not simply anti-inflammatory.

On cancer, SIRT6 flips sides depending on tissue and stage. It clearly promotes tumour growth in osteosarcoma and papillary thyroid cancer, and clearly suppresses it in bladder, nasopharyngeal, and glioma. In melanoma, breast, lung, pancreatic, liver, prostate, colon, ovarian, and blood cancers, the direction changes with cancer stage or cell line — sometimes tumour-suppressor, sometimes oncogene. This is the clearest single-source explanation of why SIRT6 in cancer is not a "raise it, live longer" story.

Key findings

  • Consolidates SIRT6's three enzymatic activities — NAD+-dependent deacetylation (H3K9, H3K18, H3K56 and non-histone substrates including p53, PKM2, Ku70, GCN5), defatty-acylation (TNF-α K19 and K20, R-Ras2), and mono-ADP-ribosylation (PARP1 K521, KAP1, BAF170).
  • Free fatty acids increase SIRT6 deacetylation activity approximately 35-fold at physiological concentrations, providing an endogenous regulatory lever on the enzyme.
  • Maps four mechanisms by which SIRT6 delays ageing: promotion of base excision, nucleotide excision, and double-strand break repair; maintenance of normal telomere and heterochromatin structure; restoration of gluconeogenic and NAD+ metabolism in ageing tissue; and suppression of the senescence-associated secretory phenotype (SASP).
  • Documents SIRT6's role in immunosenescence — SIRT6-knockout mice have reduced numbers and function of conventional dendritic cells, impaired MHCII expression, and reduced IL-12 production, consistent with the immune decline seen in age-related disease.
  • Catalogues SIRT6's dual role in cancer across 14 tumour types, with a full-page summary table. Tumour-suppressor-only in bladder, nasopharyngeal, and glioma. Oncogene-only in osteosarcoma and papillary thyroid. Context-dependent (varies by cell line, cancer stage, or study) in melanoma, breast, lung, pancreatic, liver, prostate, colon, ovarian, and haematological cancers.
  • Notes that SIRT6-mediated M2 macrophage polarisation is anti-inflammatory in healthy tissue but pro-tumorigenic in cancer, because M2-polarised macrophages support the immunosuppressive tumour microenvironment. This is the mechanistic link between SIRT6's ageing role and its cancer role.

What this study can and cannot tell us

This is a narrative review, not a systematic review or meta-analysis. The authors did not use pre-registered search strategies, PRISMA-style methodology, or formal quality assessment tools. Reader should treat conclusions as informed synthesis rather than statistical summary.

Almost all evidence catalogued is preclinical — animal knockout and overexpression models, human cell lines, and molecular biochemistry. The review does not analyse published human clinical trial data for SIRT6 activators or inhibitors, because none had been completed at time of publication.

The cancer section, which is the review's most distinctive contribution, is a synthesis of studies that themselves used different methods (siRNA knockdown, CRISPR knockout, pharmacological inhibition, forced overexpression) in different cell lines. Where studies disagree on SIRT6's direction of effect within a single cancer, the review presents both sides but does not attempt to reconcile them.

Published in 2022, so does not incorporate more recent work including the 2023 chondrocyte data on SIRT6 activation with MDL-800, the 2025 fucoidan senotherapeutic preprints, or the 2026 Bar-Ilan hepatic chromatin reversal paper.

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