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Acidic extracellular pH promotes epithelial mesenchymal transition in Lewis lung carcinoma model.

Suzuki A, Maeda T, Baba Y, Shimamura K, Kato Y - Cancer Cell Int. (2014)

Bottom Line: Both variants showed decreased levels of E-cadherin and increased levels of vimentin at pH e 6.8.Acidic pH e also induced expression of mRNAs encoding the E-cadherin repressors, Zeb2, Twist1 and Twist2, as well as enhancing cell motility and in vitro invasion through Matrigel®.Acidic pH e can induce EMT in some types of carcinoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Koriyama, Japan ; Department of Oral Physiology and Biochemistry, Ohu University Graduate School of Dentistry, Koriyama, Japan.

ABSTRACT

Background: Epithelial mesenchymal transition (EMT) is thought to be an essential feature of malignant tumor cells when they spread into the stroma. Despite the extracellular acidity of tumor tissues, the effect of acidic extracellular pH (pH e ) on EMT in carcinoma models, including the Lewis lung carcinoma (LLC) model, remains unclear.

Methods: High and low metastatic LLC variants were generated by repeated tail vein injection of metastatic cells. DMEM/F12 medium, which has been supplemented with 15 mM HEPES, 4 mM phosphoric acid, and 1 g/L NaHCO3 and adjusted to the desire pH with HCl or NaOH, was used for cell culture. EMT marker gene expression was determined by quantitative reverse transcription-polymerase chain reaction. Migration and invasion activities were analyzed by wound healing assay and the Boyden chamber assay through Matrigel®, respectively.

Results: Low metastatic variant LLCm1 cells showed a cobble-stone like morphology at pH e 7.4. At pH e 6.8, however, their morphology became fibroblastic, similar in shape to high metastatic variant LLCm4 cells. Steady state levels of matrix metalloproteinase-9 (Mmp9) mRNA were induced by acidic pH e , maximizing at pH 6.8, with the levels of Mmp9 mRNA higher in LLCm4 than in LLCm1 cells. Both variants showed decreased levels of E-cadherin and increased levels of vimentin at pH e 6.8. Acidic pH e also induced expression of mRNAs encoding the E-cadherin repressors, Zeb2, Twist1 and Twist2, as well as enhancing cell motility and in vitro invasion through Matrigel®.

Conclusions: Acidic pH e can induce EMT in some types of carcinoma.

No MeSH data available.


Related in: MedlinePlus

Morphological changes of LLC variants in acidic medium. Cultures were pretreated overnight with serum-free DMEM/12 at pH 7.4 and incubated in serum-free medium at pH 6.8 or 7.4 for 24 h. Photographs were taken under an inverted phase contrast microscope. Representative results were shown from three or more independent experiments. Bar, 50 μm.
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Fig4: Morphological changes of LLC variants in acidic medium. Cultures were pretreated overnight with serum-free DMEM/12 at pH 7.4 and incubated in serum-free medium at pH 6.8 or 7.4 for 24 h. Photographs were taken under an inverted phase contrast microscope. Representative results were shown from three or more independent experiments. Bar, 50 μm.

Mentions: Since the optimal pHe value for MMP-9 induction was about pH 6.8, further experiments compared the effects of neutral (pH 7.4) and acidic (pH 6.8) pHe. At neutral pHe, LLCm1 cells had a cobble-stone appearance. When cultured at acidic pHe, however, their morphology became fibroblastic and of similar shape as LLCm4 cells (Figure 4). In contrast to LLCm1 cells, change in pHe did not induce morphological changes in LLCm4 cells. These morphological observations suggested that acidic pHe may induce EMT, however, the interesting lack of effect in the already mesenchymal cells should be mentioned.Figure 4


Acidic extracellular pH promotes epithelial mesenchymal transition in Lewis lung carcinoma model.

Suzuki A, Maeda T, Baba Y, Shimamura K, Kato Y - Cancer Cell Int. (2014)

Morphological changes of LLC variants in acidic medium. Cultures were pretreated overnight with serum-free DMEM/12 at pH 7.4 and incubated in serum-free medium at pH 6.8 or 7.4 for 24 h. Photographs were taken under an inverted phase contrast microscope. Representative results were shown from three or more independent experiments. Bar, 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4260188&req=5

Fig4: Morphological changes of LLC variants in acidic medium. Cultures were pretreated overnight with serum-free DMEM/12 at pH 7.4 and incubated in serum-free medium at pH 6.8 or 7.4 for 24 h. Photographs were taken under an inverted phase contrast microscope. Representative results were shown from three or more independent experiments. Bar, 50 μm.
Mentions: Since the optimal pHe value for MMP-9 induction was about pH 6.8, further experiments compared the effects of neutral (pH 7.4) and acidic (pH 6.8) pHe. At neutral pHe, LLCm1 cells had a cobble-stone appearance. When cultured at acidic pHe, however, their morphology became fibroblastic and of similar shape as LLCm4 cells (Figure 4). In contrast to LLCm1 cells, change in pHe did not induce morphological changes in LLCm4 cells. These morphological observations suggested that acidic pHe may induce EMT, however, the interesting lack of effect in the already mesenchymal cells should be mentioned.Figure 4

Bottom Line: Both variants showed decreased levels of E-cadherin and increased levels of vimentin at pH e 6.8.Acidic pH e also induced expression of mRNAs encoding the E-cadherin repressors, Zeb2, Twist1 and Twist2, as well as enhancing cell motility and in vitro invasion through Matrigel®.Acidic pH e can induce EMT in some types of carcinoma.

View Article: PubMed Central - PubMed

Affiliation: Department of Oral Function and Molecular Biology, Ohu University School of Dentistry, Koriyama, Japan ; Department of Oral Physiology and Biochemistry, Ohu University Graduate School of Dentistry, Koriyama, Japan.

ABSTRACT

Background: Epithelial mesenchymal transition (EMT) is thought to be an essential feature of malignant tumor cells when they spread into the stroma. Despite the extracellular acidity of tumor tissues, the effect of acidic extracellular pH (pH e ) on EMT in carcinoma models, including the Lewis lung carcinoma (LLC) model, remains unclear.

Methods: High and low metastatic LLC variants were generated by repeated tail vein injection of metastatic cells. DMEM/F12 medium, which has been supplemented with 15 mM HEPES, 4 mM phosphoric acid, and 1 g/L NaHCO3 and adjusted to the desire pH with HCl or NaOH, was used for cell culture. EMT marker gene expression was determined by quantitative reverse transcription-polymerase chain reaction. Migration and invasion activities were analyzed by wound healing assay and the Boyden chamber assay through Matrigel®, respectively.

Results: Low metastatic variant LLCm1 cells showed a cobble-stone like morphology at pH e 7.4. At pH e 6.8, however, their morphology became fibroblastic, similar in shape to high metastatic variant LLCm4 cells. Steady state levels of matrix metalloproteinase-9 (Mmp9) mRNA were induced by acidic pH e , maximizing at pH 6.8, with the levels of Mmp9 mRNA higher in LLCm4 than in LLCm1 cells. Both variants showed decreased levels of E-cadherin and increased levels of vimentin at pH e 6.8. Acidic pH e also induced expression of mRNAs encoding the E-cadherin repressors, Zeb2, Twist1 and Twist2, as well as enhancing cell motility and in vitro invasion through Matrigel®.

Conclusions: Acidic pH e can induce EMT in some types of carcinoma.

No MeSH data available.


Related in: MedlinePlus