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Short summary of the research and contribution to the field

This review discusses intercellular mitochondrial trafficking as an emerging mechanism that may regulate tumor progression, metabolic adaptation, therapy resistance, and cancer stem cell plasticity. The manuscript describes how mitochondria may be transferred between tumor cells, stromal cells, immune cells, and other components of the tumor microenvironment through mechanisms such as tunneling nanotubes, extracellular vesicles, gap junctions, and cell fusion.

The central idea is that transferred mitochondria can help metabolically stressed cancer cells restore oxidative phosphorylation, regulate redox balance, survive hypoxia, resist therapy, and acquire more plastic or stem-like phenotypes. The review also highlights the possible role of transferred mitochondrial DNA, metabolites, and retrograde signaling in linking metabolic state to epigenetic remodeling and transcriptional reprogramming.

This work is timely because cancer progression is increasingly understood not only as a genetic process, but also as a dynamic metabolic and microenvironment-driven process. By focusing on mitochondrial exchange as a possible regulator of tumor adaptability and cancer stem cell states, the manuscript addresses an important and rapidly developing area in cancer biology.

Positive feedback / strengths

1. Timely and important topic. Mitochondrial transfer is an emerging concept in cancer biology, especially in relation to tumor metabolism, therapy resistance, stromal interaction, and cancer cell plasticity.

2. Strong conceptual connection between metabolism and phenotype. The review appropriately links mitochondrial trafficking to oxidative phosphorylation, redox balance, epigenetic regulation, transcriptional reprogramming, and cancer stem-like features.

3. Good tumor microenvironment framing. The manuscript recognizes that mitochondrial transfer is not only a tumor-cell-intrinsic phenomenon, but may involve stromal cells, immune cells, and other cells within the tumor microenvironment.

4. Relevant discussion of transfer routes. Including tunneling nanotubes, extracellular vesicles, gap junctions, and cell fusion gives the review a useful mechanistic framework.

5. Therapeutic relevance. The idea that disrupting mitochondrial trafficking could reduce tumor adaptability and therapy resistance is clinically meaningful and may help guide future experimental and translational studies.

Major issues

1. The title may overstate the strength of current evidence

The title describes intercellular mitochondrial trafficking as a “master regulator” of tumor progression and cancer stem cell plasticity. This is an interesting hypothesis, but the term “master regulator” may be too strong unless the review provides broad, consistent, causal evidence across multiple tumor types and experimental models.

Suggested improvement: The authors should consider softening the title or clearly framing “master regulator” as a hypothesis. Possible alternatives:

• “Intercellular Mitochondrial Trafficking as an Emerging Regulator of Tumor Progression and Cancer Stem Cell Plasticity”

• “Intercellular Mitochondrial Trafficking in Tumor Progression and Cancer Stem Cell Plasticity”

• “Mitochondrial Transfer as a Driver of Tumor Adaptation and Cancer Cell Plasticity”

This would make the manuscript more balanced and scientifically cautious.

2. The review should clearly distinguish evidence from hypothesis

The manuscript appears to connect mitochondrial transfer with many important cancer behaviors, including therapy resistance, metastasis, stemness, metabolic restoration, and epigenetic remodeling. These links are plausible, but they may not all be equally well established.

Suggested improvement: The authors should classify evidence into categories such as:

• directly demonstrated in cancer models

• demonstrated in non-cancer injury/regeneration models

• inferred from metabolic or transcriptomic changes

• proposed but not yet experimentally proven

A summary table would be very useful:

MechanismCancer type/modelDonor cellRecipient cellEvidence for mitochondrial transferFunctional outcomeStrength of evidence

This would help readers separate established biology from emerging hypotheses.

3. Mechanisms of mitochondrial transfer need deeper comparison

The manuscript lists several transfer mechanisms, including tunneling nanotubes, extracellular vesicles, gap junctions, and cell fusion. However, these mechanisms are biologically distinct and may have different relevance depending on tumor type, microenvironment, and stress condition.

Suggested improvement: The authors should compare these mechanisms more directly:

• which mechanisms transfer intact functional mitochondria versus mitochondrial fragments or mtDNA

• whether transfer is contact-dependent or contact-independent

• whether transfer is directional or bidirectional

• how hypoxia, chemotherapy, radiation, inflammation, or immune pressure influence transfer

• how each mechanism is experimentally detected

• major limitations and artifacts for each method

This would strengthen the mechanistic clarity of the review.

4. Cancer stem cell plasticity needs clearer definition and evidence

The review links mitochondrial transfer to cancer stem cell plasticity. This is potentially important, but “stemness” and “plasticity” are broad concepts and can be measured in many ways.

Suggested improvement: The authors should define what they mean by cancer stem cell plasticity and specify the evidence used to support it, such as:

• tumorsphere formation

• ALDH activity

• CD44/CD24 or other surface markers

• stemness transcription factors such as SOX2, OCT4, NANOG, KLF4, MYC

• drug-tolerant persister states

• EMT/mesenchymal transition

• tumor-initiation ability in vivo

• single-cell transcriptomic evidence

The manuscript would be stronger if it clearly explains whether mitochondrial transfer causes stem-like features or is associated with already-existing stem-like states.

5. The review should address alternative explanations

Cancer cells under stress can adapt through many mechanisms besides mitochondrial transfer, including metabolic rewiring, selection of resistant clones, autophagy, mitophagy, epithelial–mesenchymal transition, immune evasion, altered nutrient uptake, and epigenetic adaptation.

Suggested improvement: The authors should discuss how mitochondrial trafficking can be distinguished from these alternative mechanisms. For example:

• Does blocking mitochondrial transfer reverse resistance?

• Does recipient-cell mitochondrial function improve after transfer?

• Are transferred mitochondria integrated long-term or transiently?

• Are observed effects due to mitochondrial transfer specifically or due to secreted cytokines, exosomes, growth factors, or stress signaling?

This would make the review more critical and scientifically rigorous.

6. Experimental detection methods require careful discussion

Mitochondrial transfer studies can be technically challenging. Fluorescent dyes, mitochondrial reporters, extracellular vesicle tracking, and imaging approaches can produce artifacts if not carefully controlled.

Suggested improvement: The authors should include a section on experimental methods and limitations, including:

• mitochondrial dyes versus genetically encoded reporters

• live-cell imaging

• confocal/super-resolution microscopy

• flow cytometry-based transfer assays

• mtDNA haplotype tracking

• single-cell sequencing

• mitochondrial functional assays

• controls for dye leakage, cell fusion, phagocytosis, dead-cell debris, and extracellular vesicle contamination

This is important because claims of mitochondrial transfer require strong technical validation.

7. Therapeutic targeting needs a more cautious and practical discussion

The manuscript suggests that disrupting mitochondrial trafficking may reveal new therapeutic strategies. This is an exciting idea, but many transfer pathways may also be important in normal tissue repair, immune function, and stress recovery.

Suggested improvement: The authors should discuss:

• therapeutic windows

• toxicity risks

• specificity for tumor cells versus normal cells

• whether targeting tunneling nanotubes or EV release would be too broad

• possible combination with chemotherapy, radiation, immunotherapy, or metabolic inhibitors

• biomarkers to identify tumors dependent on mitochondrial transfer

• preclinical evidence for targeting mitochondrial transfer

This would make the translational section more realistic.

8. Long-term fate of transferred mitochondria should be emphasized

The abstract notes that the long-term impact of mitochondrial integration remains unclear. This is an important unresolved question.

Suggested improvement: The authors should expand this into a dedicated subsection addressing:

• whether transferred mitochondria replicate in recipient cells

• whether they are degraded by mitophagy

• whether donor mtDNA persists long-term

• whether transferred mitochondria alter nuclear gene expression

• whether mitochondrial transfer leads to stable phenotype change or transient metabolic rescue

• how mitochondrial heteroplasmy may influence tumor evolution

This would add depth to the review.

Minor issues

1. Define key terms early. Terms such as tunneling nanotubes, retrograde signaling, mitochondrial trafficking, mitochondrial transfer, cancer stem cell plasticity, and metabolic epigenetics should be defined clearly.

2. Use consistent terminology. The manuscript should distinguish “mitochondrial trafficking,” “mitochondrial transfer,” “mitochondrial donation,” and “mitochondrial exchange.”

3. Add a mechanism figure. A schematic showing donor cells, recipient tumor cells, tunneling nanotubes, extracellular vesicles, gap junctions, and downstream effects would improve readability.

4. Add a tumor-type table. A table summarizing evidence across breast cancer, leukemia, glioblastoma, melanoma, lung cancer, ovarian cancer, and other tumor types would be helpful.

5. Clarify whether transferred material includes whole mitochondria, mtDNA, mitochondrial fragments, or metabolites. These are biologically different and may have different consequences.

6. Discuss immune-cell mitochondrial transfer. The review should clarify whether mitochondrial transfer supports tumor survival, suppresses immune cells, rescues immune cells, or has context-dependent effects.

7. Discuss mitochondrial quality. Donor mitochondria may be functional, damaged, stressed, or immunogenic. This distinction may influence whether transfer promotes survival or cell death.

8. Avoid overgeneralization. Statements such as “mitochondrial transfer promotes tumor progression” should be tied to specific models or cancer types.

9. Add a limitations section. A clear limitations section would strengthen the review, especially regarding detection artifacts, causality, model limitations, and translational uncertainty.

10. Improve clinical translation framing. The therapeutic section should specify what would need to be validated before mitochondrial-transfer targeting could move toward clinical development.

Overall assessment

This is a timely and conceptually interesting review on intercellular mitochondrial trafficking in cancer progression, metabolic adaptation, and cancer stem cell plasticity. The topic is important because mitochondrial transfer may help explain how cancer cells survive metabolic stress, adapt to therapy, and interact with stromal or immune cells in the tumor microenvironment.

The main strengths are the broad conceptual framework, the connection between metabolism and plasticity, and the focus on therapeutic implications. The most important improvements would be to soften overstrong claims, clearly distinguish proven mechanisms from hypotheses, compare transfer mechanisms more deeply, discuss experimental artifacts, and provide structured tables summarizing evidence across cancer types and transfer routes.

With these revisions, the manuscript would become a stronger and more balanced review of mitochondrial transfer as an emerging mechanism of tumor adaptation and a potential therapeutic vulnerability.

Competing interests

The author declares that they have no competing interests.

Use of Artificial Intelligence (AI)

The author declares that they used generative AI to come up with new ideas for their review.