How does mutant KRAS rewrite CRC chromatin with lactate?
In KRAS-mutant colorectal cancer, extra lactate boosts H3K9 lactylation, which opens chromatin at GRAMD1A and fuels cholesterol-driven growth; blocking H3K9la or GRAMD1A shrinks PDX tumors.
Source
KRAS mutation increases histone H3 lysine 9 lactylation (H3K9la) to promote colorectal cancer progression by facilitating cholesterol transporter GRAMD1A expression
Study at a glance
- Design
- Animal / in-vitro — KRAS-mutant vs wild-type CRC tissues, cell lines, ChIP/RNA-seq, and PDX mice testing H3K9la–GRAMD1A–cholesterol signaling
- N
- N=167 · Immunofluorescence on 130 CRC and 37 normal colon tissues; plus cell lines, TCGA, and KRAS-mutant/wild-type PDX models
- Population
- Human colorectal tumors and matched normals, CRC cell lines, TCGA transcriptomes, and CRC patient-derived xenograft mice
- Outcome
- H3K9la/lactylation levels, GRAMD1A expression, cholesterol metabolism, proliferation/migration, survival, and PDX tumor growth
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What they did
Compared lactylation/H3K9la in 130 CRC vs 37 normal tissues and KRAS-mutant vs wild-type cells, linked levels to stage/survival, traced GRAMD1A via H3K9la chromatin accessibility, and treated KRAS-mutant and wild-type PDX mice with LDH or GRAMD1A inhibitors.
What they found
KRAS-mutant tumors had higher lactate-driven H3K9la; high H3K9la predicted worse survival. Mutant KRAS induced GRAMD1A, promoting cholesterol metabolism, growth, and metastasis. Inhibiting H3K9la or GRAMD1A cut PDX growth, more so in KRAS-mutant PDX.
The limits
What it doesn't show
Tissue associations and PDX responses do not prove a ready human drug; KRAS is mutated in ~40% of CRC so wild-type tumors may respond less, and cholesterol effects were not a randomized clinical trial.
Key terms
- H3K9la
- Lactylation of histone H3 lysine 9, a lactate-derived epigenetic mark.
- KRAS
- Oncogene mutated in about 40% of CRC, reprogramming glycolysis and lactate.
- GRAMD1A
- Cholesterol transporter induced via H3K9la-accessible chromatin in mutant KRAS CRC.
- Histone lactylation
- Epigenetic modification; 28 potential sites on core histones, including H3K9la.
- PDX
- Patient-derived xenograft mouse model used to test H3K9la/GRAMD1A blockade.
- Pan-Kla
- Pan-lysine lactylation staining used on CRC vs normal tissues.
Flashcards
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Quiz yourself
The histone mark emphasized is:
Common questions
How common is KRAS mutation in CRC?
Approximately 40% of patients.
What histone mark rose?
H3K9 lactylation (H3K9la), driven by intracellular lactate.
Downstream effector?
Cholesterol transporter GRAMD1A.
Did targeting work in mice?
Yes—H3K9la or GRAMD1A inhibition reduced PDX tumor growth, more in KRAS-mutant PDX.
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