Hypothesis

Ancestry‑specific differences in nuclear‑encoded mitochondrial function modulate reactive oxygen species (ROS) production in hematopoietic stem cells (HSCs), leading to preferential formation of mosaic chromosomal alterations (mCAs) that, once expanded, secrete a senescence‑associated secretory phenotype (SASP) rich in IL‑6, IL‑8 and TGF‑β. These circulating factors promote epithelial transformation in lung, breast and colon tissues, thereby explaining why mCAs confer organ‑specific cancer mortality beyond mere incidence. The hypothesis integrates (1) the observed excess of autosomal mCAs in European‑ancestry individuals and elevated chromosome X mCAs in African/Hispanic females, (2) the causal link between specific copy‑number variants and Alzheimer’s‑related gene expression, and (3) the sex‑specific decline of mitochondrial DNA copy number associated with muscle weakness.

Mechanistic Model

1. Genetic background – Polygenic risk scores (PRS) for lung, breast and colorectal cancer enrich for variants in nuclear‑encoded mitochondrial genes (e.g., TFAM, POLG, SOD2) that differ in allele frequency across ancestries.
2. Mitochondrial stress – Ancestry‑linked allelic variation alters oxidative phosphorylation efficiency, raising basal ROS in HSCs. Increased ROS causes double‑strand breaks and mis‑segregation, generating large somatic copy‑number losses (the mCA type with highest lung cancer OR).
3. Clonal expansion – Cells harboring mCAs acquire a growth advantage via loss of tumor‑suppressor loci (e.g., CDKN2A) and simultaneously activate a SASP through cGAS‑STING sensing of cytosolic DNA.
4. Non‑cell‑autonomous carcinogenesis – SASP cytokines diffuse systemically, creating a pro‑inflammatory microenvironment that stimulates epithelial proliferation, inhibits apoptosis, and augments mutagenicity in target organs, thereby increasing cancer‑specific mortality.
5. Sex‑chromosome specificity – In African and Hispanic females, higher baseline expression of X‑linked mitochondrial regulators (e.g., MTND genes) predisposes to chromosome X mCAs, which may modulate X‑linked immune genes and further shape the SASP profile.

Testable Predictions

• Individuals with high cancer PRS and expanded mCAs will show (a) elevated mitochondrial ROS in CD34+ HSCs, (b) reduced mtDNA copy number, and (c) higher plasma IL‑6/IL‑8/TGF‑β compared with PRS‑matched controls lacking mCAs.
• Ancestry‑stratified analysis will reveal that European‑ancestry carriers of autosomal mCAs have higher ROS and SASP markers, whereas African/Hispanic female carriers of chromosome X mCAs exhibit a distinct cytokine skew (elevated CXCL10, IFN‑γ).
• Pharmacological reduction of mitochondrial ROS (using "MitoQ" or SS‑31) in humanized mouse models transplanted with PRS‑high HSCs will decrease mCA formation, lower circulating SASP factors, and reduce spontaneous lung, breast and colon tumor incidence.
• CRISPR‑mediated correction of a high‑risk TFAM variant in iPSC‑derived HSCs will normalize ROS, diminish mCA emergence, and attenuate SASP secretion.

Experimental Design

Human cohort – Recruit 1,200 participants (400 each of European, African, Hispanic ancestry) stratified by PRS tertials and mCA status (detected by low‑pass whole‑blood sequencing). Measure:

• mtDNA copy number (qPCR)
• Mitochondrial ROS (MitoSOX flow cytometry)
• Plasma cytokine panel (Luminex)
• mCA burden and cell fraction (shallow WGS)

Intervention trial – In a subset of high‑PRS mCA+ participants, administer "MitoQ" 20 mg daily for 6 months; primary endpoints: change in mCA VAF, ROS, and SASP levels.

Mouse validation – Generate NSG mice engrafted with HSCs from human iPSCs carrying either ancestral‑specific TFAM alleles or CRISPR‑edited controls. Monitor mCA formation by single‑cell DNA sequencing, serum cytokines, and tumor development after carcinogen exposure (e.g., NNK for lung, DMBA for breast, AOM/DSS for colon).

Implications

If validated, this hypothesis would reposition mCA screening as a biomarker of mitochondrial‑driven inflammaging, justify ancestry‑tailored antioxidant prophylaxis, and suggest that targeting the mCA‑SASP axis could reduce cancer mortality independent of tumor stage. It also links the CNV‑gene networks identified in Alzheimer’s disease to a broader systemic aging phenotype via mitochondrial dysfunction.

Keywords: mosaic chromosomal alterations, mitochondrial ROS, ancestry‑specific genetics, senescence‑associated secretory phenotype, cancer mortality