Research on Traditional Chinese Medicine for Treating MSH6 Gene Mutation-Related Diseases

Background and Potential

MSH6 gene mutations are closely associated with Lynch syndrome and increase the risk of cancers such as colorectal and endometrial cancer. In TCM, tumors are attributed to “deficiency of vital qi” and “stasis of toxic blood.” TCM may regulate abnormal cell proliferation and DNA repair defects caused by MSH6 mutations through mechanisms like strengthening vital qi, promoting blood circulation, and clearing heat and toxins. Herbs like Astragalus and Ginseng can enhance immunity, while Salvia and Notoginseng may improve the microenvironment and inhibit tumor cell proliferation. Compound formulas like Sijunzi Decoction and Guipi Decoction regulate the spleen and stomach, while heat-clearing formulas like Huanglian Jiedu Decoction may indirectly address MSH6 mutation-related pathologies through anti-inflammatory and antioxidant effects.

Although no direct clinical studies exist on TCM for MSH6 mutations, the role of TCM in anti-tumor and immune regulation is well-documented. For instance, Astragalus polysaccharides may enhance DNA repair by activating immune signaling pathways (e.g., TLR4/NF-κB), potentially aiding MSH6 mutation-related DNA mismatch repair defects. Thus, exploring single herbs and compound formulas for MSH6 mutation-related diseases holds significant potential.

Research Methods

1. Herb Screening and Formula Design

• Single Herb Screening: Select herbs with anti-tumor, immunomodulatory, and antioxidant properties, such as Astragalus, Ginseng, Coptis, Salvia, and Notoginseng. Use network pharmacology to analyze active components (e.g., Astragalus polysaccharides, tanshinone) and their interactions with MSH6 mutation-related pathways (e.g., PI3K/AKT, MAPK).
• Compound Formula Design: Based on TCM syndrome differentiation, design formulas targeting “qi deficiency and blood stasis” or “heat-toxin accumulation.” For example, modify Sijunzi Decoction (with Astragalus, Codonopsis, and Atractylodes as main herbs) by adding Salvia and Red Peony to promote blood circulation.
• Pharmacological Basis: Use high-performance liquid chromatography (HPLC) to analyze key active components in formulas, determining dosage and mechanisms.

2. Cell Model Construction

• Cell Line Selection: Use HEK293 cells (human embryonic kidney cells) for gene editing or Caco-2 cells (human colorectal adenocarcinoma cells) to model MSH6 mutation-related cancers.
• Precise Gene Editing:
  1. Design gRNA targeting MSH6 gene (e.g., c.3261dupC mutation).
  2. Construct CRISPR/Cas9 plasmids containing gRNA and Cas9 sequences.
  3. Transfect plasmids into cells via electroporation or lipofection.
  4. Screen for stable MSH6 mutant cell lines using single-cell cloning.
• Mutation Validation: Verify MSH6 mutations via Sanger sequencing; assess MSH6 protein expression with Western blot; evaluate DNA mismatch repair defects using microsatellite instability (MSI) assays.

3. TCM Intervention Experiments

• In Vitro Experiments:
  1. Divide MSH6 mutant cells into control, single herb (e.g., Astragalus polysaccharides, tanshinone), and compound formula groups (e.g., modified Sijunzi Decoction).
  2. Measure cell proliferation (MTT assay), apoptosis (Annexin V/PI staining), and DNA repair capacity (comet assay).
  3. Analyze key signaling pathways (e.g., PI3K/AKT, NF-κB) using qPCR and Western blot.
• Dose Optimization: Determine effective doses and toxicity thresholds of single herbs and formulas through gradient concentration experiments.

4. Validation Methods

• Functional Validation: Use MSI assays to confirm whether TCM improves microsatellite instability caused by MSH6 mutations. Assess DNA damage repair with comet assays.
• Molecular Mechanism Validation: Examine expression changes in key genes (e.g., MLH1, PMS2) and signaling pathway molecules to identify TCM’s molecular targets.
• In Vivo Validation: Construct MSH6 mutant mouse models (e.g., Msh6 knockout mice), administer TCM, and observe tumor incidence, survival, and immune microenvironment changes.

Expected Outcomes and Significance

TCM may improve DNA repair defects, inhibit tumor cell proliferation, and enhance immunity in MSH6 mutant cells through multi-target, multi-pathway mechanisms. These findings could provide a theoretical basis for TCM in treating Lynch syndrome and other hereditary cancers, advancing the integration of TCM with precision medicine.