Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia
Lactic acidosis, glucose deprivation and hypoxia are conditions frequently found in solid tumors because, among other reasons, tumors switch to Warburg effect and secrete high levels of lactate, which decreases the pH (<6. 9) in the microenvironment. We hypothesized that lung cancer cells con...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Frontiers Media S.A.
2019-10-01
|
| Series: | Frontiers in Oncology |
| Subjects: | |
| Online Access: | https://www.frontiersin.org/article/10.3389/fonc.2019.01053/full |
| _version_ | 1819035311547613184 |
|---|---|
| author | Susana Romero-Garcia Heriberto Prado-Garcia Alma Delia Valencia-Camargo Abraham Alvarez-Pulido |
| author_facet | Susana Romero-Garcia Heriberto Prado-Garcia Alma Delia Valencia-Camargo Abraham Alvarez-Pulido |
| author_sort | Susana Romero-Garcia |
| collection | DOAJ |
| description | Lactic acidosis, glucose deprivation and hypoxia are conditions frequently found in solid tumors because, among other reasons, tumors switch to Warburg effect and secrete high levels of lactate, which decreases the pH (<6. 9) in the microenvironment. We hypothesized that lung cancer cells consume lactate and induce mitochondrial biogenesis to support survival and proliferation in lactic acidosis with glucose deprivation even under hypoxia. We examined lung adenocarcinoma cell lines (A-427 and A-549), a breast cancer cell line (MCF-7) and non-transformed fibroblasts (MRC-5). Cells were cultured using RPMI-1640 medium with 28 mM lactate varying pH (6.2 or 7.2) under normoxia (atmospheric O2) or hypoxia (2% O2). Cellular growth was followed during 96 h, as well as lactate, glutamine and glutamate levels, which were measured using a biochemical analyzer. The expression levels of monocarboxylate transporters (MCT1 and MCT4) were evaluated by flow cytometry. To evaluate mitochondrial biogenesis, mitochondrial mass was analyzed by flow cytometry and epifluorescence microscopy. Also, mitochondrial DNA (mtDNA) was measured by qPCR. Transcript levels of Nuclear Respiratory Factors (NRF-1 and NRF-2) and Transcription Factor A Mitochondrial (TFAM) were determined using RT-qPCR. The specific growth rate of A-549 and A-427 cells increased in lactic acidosis compared with neutral lactosis, either under normoxia or hypoxia, a phenomenon that was not observed in MRC-5 fibroblasts. Under hypoxia, A-427 and MCF-7 cells did not survive in neutral lactosis but survived in lactic acidosis. Under lactic acidosis, A-427 and MCF-7 cells increased MCT1 levels, reduced MCT4 levels and consumed higher lactate amounts, while A-549 cells consumed glutamine and decreased MCT1 and MCT4 levels with respect to neutral lactosis condition. Lactic acidosis, either under normoxia or hypoxia, increased mitochondrial mass and mtDNA levels compared with neutral lactosis in all tumor cells but not in fibroblasts. A-549 and MCF-7 cells increased levels of NRF-1, NRF-2, and TFAM with respect to MRC-5 cells, whereas A-427 cells upregulated these transcripts under lactic acidosis compared with neutral lactosis. Thus, lung adenocarcinoma cells induce mitochondrial biogenesis to support survival and proliferation in lactic acidosis with glucose deprivation. |
| first_indexed | 2024-12-21T07:47:37Z |
| format | Article |
| id | doaj.art-4289e1ae1aa74db397dffbd87df4c8d4 |
| institution | Directory Open Access Journal |
| issn | 2234-943X |
| language | English |
| last_indexed | 2024-12-21T07:47:37Z |
| publishDate | 2019-10-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Oncology |
| spelling | doaj.art-4289e1ae1aa74db397dffbd87df4c8d42022-12-21T19:11:10ZengFrontiers Media S.A.Frontiers in Oncology2234-943X2019-10-01910.3389/fonc.2019.01053486787Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under HypoxiaSusana Romero-GarciaHeriberto Prado-GarciaAlma Delia Valencia-CamargoAbraham Alvarez-PulidoLactic acidosis, glucose deprivation and hypoxia are conditions frequently found in solid tumors because, among other reasons, tumors switch to Warburg effect and secrete high levels of lactate, which decreases the pH (<6. 9) in the microenvironment. We hypothesized that lung cancer cells consume lactate and induce mitochondrial biogenesis to support survival and proliferation in lactic acidosis with glucose deprivation even under hypoxia. We examined lung adenocarcinoma cell lines (A-427 and A-549), a breast cancer cell line (MCF-7) and non-transformed fibroblasts (MRC-5). Cells were cultured using RPMI-1640 medium with 28 mM lactate varying pH (6.2 or 7.2) under normoxia (atmospheric O2) or hypoxia (2% O2). Cellular growth was followed during 96 h, as well as lactate, glutamine and glutamate levels, which were measured using a biochemical analyzer. The expression levels of monocarboxylate transporters (MCT1 and MCT4) were evaluated by flow cytometry. To evaluate mitochondrial biogenesis, mitochondrial mass was analyzed by flow cytometry and epifluorescence microscopy. Also, mitochondrial DNA (mtDNA) was measured by qPCR. Transcript levels of Nuclear Respiratory Factors (NRF-1 and NRF-2) and Transcription Factor A Mitochondrial (TFAM) were determined using RT-qPCR. The specific growth rate of A-549 and A-427 cells increased in lactic acidosis compared with neutral lactosis, either under normoxia or hypoxia, a phenomenon that was not observed in MRC-5 fibroblasts. Under hypoxia, A-427 and MCF-7 cells did not survive in neutral lactosis but survived in lactic acidosis. Under lactic acidosis, A-427 and MCF-7 cells increased MCT1 levels, reduced MCT4 levels and consumed higher lactate amounts, while A-549 cells consumed glutamine and decreased MCT1 and MCT4 levels with respect to neutral lactosis condition. Lactic acidosis, either under normoxia or hypoxia, increased mitochondrial mass and mtDNA levels compared with neutral lactosis in all tumor cells but not in fibroblasts. A-549 and MCF-7 cells increased levels of NRF-1, NRF-2, and TFAM with respect to MRC-5 cells, whereas A-427 cells upregulated these transcripts under lactic acidosis compared with neutral lactosis. Thus, lung adenocarcinoma cells induce mitochondrial biogenesis to support survival and proliferation in lactic acidosis with glucose deprivation.https://www.frontiersin.org/article/10.3389/fonc.2019.01053/fullmitochondrial massmitochondrial DNA (mtDNA)nuclear respiratory factor (NRF)monocarboxylate transporter (MCT)glutaminetumor growth rate |
| spellingShingle | Susana Romero-Garcia Heriberto Prado-Garcia Alma Delia Valencia-Camargo Abraham Alvarez-Pulido Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia Frontiers in Oncology mitochondrial mass mitochondrial DNA (mtDNA) nuclear respiratory factor (NRF) monocarboxylate transporter (MCT) glutamine tumor growth rate |
| title | Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia |
| title_full | Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia |
| title_fullStr | Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia |
| title_full_unstemmed | Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia |
| title_short | Lactic Acidosis Promotes Mitochondrial Biogenesis in Lung Adenocarcinoma Cells, Supporting Proliferation Under Normoxia or Survival Under Hypoxia |
| title_sort | lactic acidosis promotes mitochondrial biogenesis in lung adenocarcinoma cells supporting proliferation under normoxia or survival under hypoxia |
| topic | mitochondrial mass mitochondrial DNA (mtDNA) nuclear respiratory factor (NRF) monocarboxylate transporter (MCT) glutamine tumor growth rate |
| url | https://www.frontiersin.org/article/10.3389/fonc.2019.01053/full |
| work_keys_str_mv | AT susanaromerogarcia lacticacidosispromotesmitochondrialbiogenesisinlungadenocarcinomacellssupportingproliferationundernormoxiaorsurvivalunderhypoxia AT heribertopradogarcia lacticacidosispromotesmitochondrialbiogenesisinlungadenocarcinomacellssupportingproliferationundernormoxiaorsurvivalunderhypoxia AT almadeliavalenciacamargo lacticacidosispromotesmitochondrialbiogenesisinlungadenocarcinomacellssupportingproliferationundernormoxiaorsurvivalunderhypoxia AT abrahamalvarezpulido lacticacidosispromotesmitochondrialbiogenesisinlungadenocarcinomacellssupportingproliferationundernormoxiaorsurvivalunderhypoxia |