Mammalian genes were long thought to be constrained within somatic cells in most cell types. This concept was challenged recently when cellular organelles including mitochondria were shown to move between mammalian cells in culture via cytoplasmic bridges. Recent research in animals indicates transfer of mitochondria in cancer and during lung injury in vivo, with considerable functional consequences. Since these pioneering discoveries, many studies have confirmed horizontal mitochondrial transfer (HMT) in vivo, and its functional characteristics and consequences have been described. Additional support for this phenomenon has come from phylogenetic studies. Apparently, mitochondrial trafficking between cells occurs more frequently than previously thought and contributes to diverse processes including bioenergetic crosstalk and homeostasis, disease treatment and recovery, and development of resistance to cancer therapy. Here we highlight current knowledge of HMT between cells, focusing primarily on in vivo systems, and contend that this process is not only (patho)physiologically relevant, but also can be exploited for the design of novel therapeutic approaches.
- MeSH
- energetický metabolismus MeSH
- fylogeneze MeSH
- mitochondrie * metabolismus MeSH
- nádory * genetika metabolismus MeSH
- savci MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- komentáře MeSH
- práce podpořená grantem MeSH
CONTEXT: CLL/SLL treatment has been transformed with Bruton tyrosine kinase inhibitors (BTKi) such as ibrutinib. Zanubrutinib, a next-generation BTKi, was designed to maximize BTK occupancy and minimize toxicity. ALPINE (NCT03734016) is a global, randomized, phase 3 study of zanubrutinib versus ibrutinib in patients with R/R CLL/SLL; presented here is a pre-planned interim analysis conducted ~12 months after 415 patients enrolled between November 5, 2018, and December 20, 2019. DESIGN: Patients were randomized 1:1 to zanubrutinib (160 mg twice daily) or ibrutinib (420 mg once daily) arms; stratification factors were age (<65 years vs ≥65 years), geographic region, refractory status, and del(17)p/TP53 mutation. MAIN OUTCOME MEASURES: Primary endpoint was investigator-assessed overall response rate (ORR) per 2008 IWCLL guidelines or Lugano criteria; the noninferiority of zanubrutinib-to-ibrutinib response ratio was evaluated at the noninferiority margin of 0.8558. If noninferiority was demonstrated, superiority of zanubrutinib versus ibrutinib in ORR was tested. RESULTS: Baseline characteristics (zanubrutinib versus ibrutinib): age ≥65 years: 62.3% versus 61.5%, male sex 68.6% versus 75%; >3 prior therapies: 7.2% versus 10.1%; del(17)p: 11.6% versus 12.5%; TP53 mutation without del(17)p: 8.2% versus 5.8%. With a median follow-up of 15 months, ORR was 78.3% versus 62.5% for zanubrutinib versus ibrutinib, respectively (2-sided P=0.0006, prespecified a=0.0099). ORR was higher for zanubrutinib in patients with del(11)q (83.6% vs 69.1%) and del(17)p (83.3% vs 53.8%); zanubrutinib had higher overall 12-month progression-free survival (PFS; 94.9% vs 84.0%) and overall survival (97.0% vs 92.7%). Significantly fewer patients had atrial fibrillation/flutter (AF) with zanubrutinib versus ibrutinib (2.5% vs 10.1%, 2-sided P=0.0014, prespecified a=0.0099). Zanubrutinib had lower rates of major bleeding (2.9% vs 3.9%), adverse events leading to discontinuation (7.8% vs 13.0%), and death (3.9% vs 5.8%). Zanubrutinib had a higher neutropenia rate (28.4% vs 21.7%) while grade ≥3 infections (12.7% vs 17.9%) were lower. CONCLUSIONS: In summary, this interim analysis showed zanubrutinib had a superior ORR, improved PFS, and lower AF rate compared to ibrutinib.
- MeSH
- adenin analogy a deriváty MeSH
- B-buněčný lymfom * farmakoterapie genetika MeSH
- chronická lymfatická leukemie * farmakoterapie genetika MeSH
- inhibitory proteinkinas * škodlivé účinky MeSH
- lidé středního věku MeSH
- lidé MeSH
- piperidiny škodlivé účinky MeSH
- pyrazoly škodlivé účinky MeSH
- pyrimidiny škodlivé účinky MeSH
- senioři MeSH
- Check Tag
- lidé středního věku MeSH
- lidé MeSH
- mužské pohlaví MeSH
- senioři MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- klinické zkoušky, fáze III MeSH
- randomizované kontrolované studie MeSH
Pancreatic cancer is one of the deadliest forms of cancer, which is attributed to lack of effective treatment options and drug resistance. Mitochondrial inhibitors have emerged as a promising class of anticancer drugs, and several inhibitors of the electron transport chain (ETC) are being clinically evaluated. We hypothesized that resistance to ETC inhibitors from the biguanide class could be induced by inactivation of SMAD4, an important tumor suppressor involved in transforming growth factor β (TGFβ) signaling, and associated with altered mitochondrial activity. Here we show that, paradoxically, both TGFβ-treatment and the loss of SMAD4, a downstream member of TGFβ signaling cascade, induce resistance to biguanides, decrease mitochondrial respiration, and fragment the mitochondrial network. Mechanistically, the resistance of SMAD4-deficient cells is mediated by increased mitophagic flux driven by MAPK/ERK signaling, whereas TGFβ-induced resistance is autophagy-independent and linked to epithelial-to-mesenchymal transition (EMT). Interestingly, mitochondria-targeted tamoxifen, a complex I inhibitor under clinical trial, overcomes resistance mediated by SMAD4-deficiency or TGFβ signaling. Our data point to differential mechanisms underlying the resistance to treatment in PDAC arising from TGFβ signaling and SMAD4 loss, respectively. The findings will help the development of mitochondria-targeted therapy for pancreatic cancer patients with SMAD4 as a plausible predictive marker.
- MeSH
- lidé MeSH
- mitofagie MeSH
- nádory slinivky břišní genetika metabolismus patologie MeSH
- protein Smad4 metabolismus MeSH
- signální transdukce MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Tumor cells without mitochondrial (mt) DNA (ρ0 cells) are auxotrophic for uridine, and their growth is supported by pyruvate. While ATP synthesis in ρ0 cells relies on glycolysis, they fail to form tumors unless they acquire mitochondria from stromal cells. Mitochondrial acquisition restores respiration that is essential for de novo pyrimidine biosynthesis and for mitochondrial ATP production. The physiological processes that underpin intercellular mitochondrial transfer to tumor cells lacking mtDNA and the metabolic remodeling and restored tumorigenic properties of cells that acquire mitochondria are not well understood. Here, we investigated the changes in mitochondrial and nuclear gene expression that accompany mtDNA deletion and acquisition in metastatic murine 4T1 breast cancer cells. Loss of mitochondrial gene expression in 4T1ρ0 cells was restored in cells recovered from subcutaneous tumors that grew from 4T1ρ0 cells following acquisition of mtDNA from host cells. In contrast, the expression of most nuclear genes that encode respiratory complex subunits and mitochondrial ribosomal subunits was not greatly affected by loss of mtDNA, indicating ineffective mitochondria-to-nucleus communication systems for these nuclear genes. Further, analysis of nuclear genes whose expression was compromised in 4T1ρ0 cells showed that immune- and stress-related genes were the most highly differentially expressed, representing over 70% of those with greater than 16-fold higher expression in 4T1 compared with 4T1ρ0 cells. The monocyte recruiting chemokine, Ccl2, and Psmb8, a subunit of the immunoproteasome that generates MHCI-binding peptides, were the most highly differentially expressed. Early monocyte/macrophage recruitment into the tumor mass was compromised in 4T1ρ0 cells but recovered before mtDNA could be detected. Taken together, our results show that mitochondrial acquisition by tumor cells without mtDNA results in bioenergetic remodeling and re-expression of genes involved in immune function and stress adaptation.
- Publikační typ
- časopisecké články MeSH
Horizontal gene transfer is known to occur in bacteria and archaea whereas higher organisms including mammals undergo vertical transfer. Our recent results demonstrate horizontal transfer of mitochondrial DNA (mtDNA) from normal host cells to tumor cells lacking mitochondrial DNA (mtDNA). This mtDNA migration results in recovery of respiration, restored tumor initiation, and metastasis.
- Publikační typ
- časopisecké články MeSH
The view that genes are constrained within somatic cells is challenged by in vitro evidence, and more recently by in vivo studies which demonstrate that mitochondria with their mitochondrial DNA (mtDNA) payload not only can, but do move between cells in tumour models and in mouse models of tissue damage. Using mouse tumour cell models without mtDNA to reflect mtDNA damage, we have shown that these cells grow tumours only after acquiring mtDNA from cells in the local microenvironment resulting in respiration recovery, tumorigenesis and metastasis. Mitochondrial transfer between cells has also been demonstrated following ischaemia-induced injury in the heart and brain and in lung epithelium, and following lung inflammation. In vitro investigations suggest that stem cells may be mitochondrial donors. The ability of mitochondria to move between cells appears to be an evolutionarily-conserved phenomenon, relevant to diseases with compromised mitochondrial function including neurodegenerative, neuromuscular and cardiovascular diseases as well as cancer and ageing.
- MeSH
- biogeneze organel MeSH
- lidé MeSH
- mitochondriální DNA genetika metabolismus MeSH
- mitochondrie genetika metabolismus patologie MeSH
- nádorové mikroprostředí MeSH
- nádory genetika metabolismus patologie MeSH
- pohyb buněk * MeSH
- poškození DNA MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Recently, we showed that generation of tumours in syngeneic mice by cells devoid of mitochondrial (mt) DNA (ρ0cells) is linked to the acquisition of the host mtDNA. However, the mechanism of mtDNA movement between cells remains unresolved. To determine whether the transfer of mtDNA involves whole mitochondria, we injected B16ρ0mouse melanoma cells into syngeneic C57BL/6Nsu9-DsRed2mice that express red fluorescent protein in their mitochondria. We document that mtDNA is acquired by transfer of whole mitochondria from the host animal, leading to normalisation of mitochondrial respiration. Additionally, knockdown of key mitochondrial complex I (NDUFV1) and complex II (SDHC) subunits by shRNA in B16ρ0cells abolished or significantly retarded their ability to form tumours. Collectively, these results show that intact mitochondria with their mtDNA payload are transferred in the developing tumour, and provide functional evidence for an essential role of oxidative phosphorylation in cancer.
- MeSH
- buněčné dýchání MeSH
- melanom patologie MeSH
- mitochondriální DNA genetika MeSH
- modely nemocí na zvířatech MeSH
- myši inbrední C57BL MeSH
- nádorové buněčné linie MeSH
- přenos genů horizontální * MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
