Gene isoforms as expression-based biomarkers predictive of drug response in vitro
NATURE COMMUNICATIONS
Authors: Safikhani, Zhaleh; Smirnov, Petr; Thu, Kelsie L.; Silvester, Jennifer; El-Hachem, Nehme; Quevedo, Rene; Lupien, Mathieu; Mak, Tak W.; Cescon, David; Haibe-Kains, Benjamin
Abstract
Next-generation sequencing technologies have recently been used in pharmacogenomic studies to characterize large panels of cancer cell lines at the genomic and transcriptomic levels. Among these technologies, RNA-sequencing enable profiling of alternatively spliced transcripts. Given the high frequency of mRNA splicing in cancers, linking this feature to drug response will open new avenues of research in biomarker discovery. To identify robust transcriptomic biomarkers for drug response across studies, we develop a meta-analytical framework combining the pharmacological data from two large-scale drug screening datasets. We use an independent pan-cancer pharmacogenomic dataset to test the robustness of our candidate biomarkers across multiple cancer types. We further analyze two independent breast cancer datasets and find that specific isoforms of IGF2BP2, NECTIN4, ITGB6, and KLHDC9 are significantly associated with AZD6244, lapatinib, erlotinib, and paclitaxel, respectively. Our results support isoform expressions as a rich resource for biomarkers predictive of drug response.
Interaction between oral squamous cell carcinoma cells and fibroblasts through TGF-beta 1 mediated by podoplanin
EXPERIMENTAL CELL RESEARCH
Authors: Li, Yao-yin; Zhou, Chuan-Xiang; Gao, Yan
Abstract
Podoplanin is upregulated in the invasive front of oral squamous cell carcinoma (OSCC). Carcinoma-associated fibroblasts (CAFs) may mediate podoplanin expression. However, the role of podoplanin in OSCC cell and fibroblast interaction remains elusive. In the present study, we found that positive podoplanin expression in OSCC cells correlated with smooth muscle actin (alpha-SMA) expression in CAFs. Using CAFs and normal mucosal fibroblasts (NFs), we established indirect and direct co-culture systems mimicking the structure of OSCC. Podoplanin-overexpressing OSCC cells promoted NF activation; in direct co-culture, but not in indirect co-culture, podoplanin-overexpressing OSCC cells increased fibroblast invasion via matrix metalloproteinase 2 (MMP-2), MMP14, and alpha v/beta 6 integrin receptor (ITGA5/ITGB6) signaling. CAFs also induced podoplanin expression through the transforming growth factor-beta 1 (TGF-beta 1)/Smad pathway. TGF-beta 1 increased the podoplanin-dependent activation of epidermal growth factor receptor (EGFR), AKT, and extracellular signal-regulated kinase (ERK) signaling. Additionally, CAFs promoted OSCC cell invasion by upregulating MMP-2 and MMP-14 expression in both indirect and direct co-culture. Taken together, our findings indicate that podoplanin regulates the interaction between OSCC cells and CAFs via the mutual paracrine effects of TGF-beta 1.