Supplementary file 1_Acidic microenvironment promotes pancreatic cancer cell survival via Akt phosphorylation-mediated suppression of apoptosis.docx

Under acidic conditions, both cell lines appeared to show reduced proliferation, an increased G₀/G₁ population, decreased Cyclin D1 and CDK4/6 expression, and attenuated ERK1/2 phosphorylation. No apparent increase in apoptosis was observed. Acidic conditions also appeared to be associated with increased Akt phosphorylation and changes in apoptosis-related proteins, including decreased Bad and Bax and increased Bcl-xL.

Pharmacological Akt inhibition under acidic conditions appeared to be accompanied by an increased apoptotic population together with increased Bad and Bax and decreased Bcl-xL expression. These observations may suggest an association between Akt signaling and survival-related cellular responses under acidic conditions; however, they do not establish a causal requirement for Akt signaling or a causal relationship between the observed protein changes and apoptosis.

ERK1/2 inhibition appeared to be associated mainly with changes in cell cycle phase distribution and related protein expression, whereas its effects on apoptosis appeared to vary between the two cell lines. Collectively, these findings may be consistent with differential changes in proliferation-associated and survival-associated signaling under extracellular acidosis, although the functional relationships among these changes remain uncertain.

The present findings were obtained exclusively in vitro and do not establish pathway-specific causality, therapeutic efficacy, or immediate clinical applicability. Further studies using complementary mechanistic approaches, appropriate in vivo models, and patient-derived systems will be required to determine the biological and clinical relevance of these observations.</p>