Crosstalk between Raf-MEK-ERK and PI3K-Akt-GSK3β signaling networks promotes chemoresistance, invasion/migration and stemness via expression of CD44 variants (v4 and v6) in oral cancer

• Published in: Oral oncology 2018-11, Vol.86, p.234-243
• Main Authors: Kashyap, Tanushree, Pramanik, Kamdeo K., Nath, Nidhi, Mishra, Prajna, Singh, Abhay K., Nagini, Siddavaram, Rana, Ajay, Mishra, Rajakishore
• Format: Article
• Language: English
• Subjects: Adult; Aged; Antineoplastic Agents - pharmacology; Antineoplastic Agents - therapeutic use; CD44s; CD44v4/6; Cell Line, Tumor; Cell Movement; Cell Proliferation; Chemoradiotherapy - methods; Chemoresistance; Cisplatin - pharmacology; Cisplatin - therapeutic use; Drug Resistance, Neoplasm; ERK1/2; Female; Gene Knockdown Techniques; Glycogen Synthase Kinase 3 beta - metabolism; Humans; Hyaluronan Receptors - genetics; Hyaluronan Receptors - metabolism; Invasion/migration; Male; MAP Kinase Signaling System - drug effects; MAP Kinase Signaling System - genetics; Middle Aged; Mouth Neoplasms - pathology; Mouth Neoplasms - therapy; Neoplasm Invasiveness; Neoplastic Stem Cells - metabolism; Notch (NICD); Phosphatidylinositol 3-Kinases - metabolism; PI3K-Akt-GSK3β; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins c-akt - metabolism; RNA, Small Interfering - metabolism; Squamous Cell Carcinoma of Head and Neck - pathology; Squamous Cell Carcinoma of Head and Neck - therapy
• ISSN: 1368-8375; 1879-0593
• DOI: 10.1016/j.oraloncology.2018.09.028

•Elevated CD44 variants expression associated with OSCC progression, chemoresistance and invasion.•CD44v4 expression is linked with Raf-MEK-ERK1/2 activation and promote cisplatin resistance.•CD44v6 expression is associated with PI3K-Akt-GSK3β activation and promote tumor invasion/migration.•CD44v4 and CD44v6 are important biomarkers to detect OSCC severity and could be exploited for therapeutic purposes. The cell-surface glycoprotein CD44 is an important oral cancer stem cell (OCSC) marker and plays significant role in oral squamous cell carcinoma (OSCC) aggressiveness, however, the regulation of CD44 is incompletely understood. In the present study, 145 fresh human OSCC tissue specimens, including 18 adjacent normal, 42 noninvasive (N0), 53 invasive tumor samples (N1-3) and 32 chemo-radiation resistant samples (RCRT), were included. The expression of CD44 standard (CD44s) and variants (CD44v4, CD44v6); the activation of pERK1/2, GSK3β, NICD (Notch) pathways; the cell viability; and the MMP-9/-2 activity were assessed using RT-PCR, immunohistochemistry, Western blotting, MTT assay and gelatin zymography. OSCC cell lines, including parental (SCC9/SCC4) and Cisplatin-resistant (CisR-SCC9/-SCC4) cells, were used. Knock down of CD44v4/CD44v6 (by siRNA) or inactivation of MAPK/PI3K pathways using specific PD98059/LY294002 was achieved for in vitro analysis of chemoresistance and invasion/migration. Elevated CD44 variants were associated with overall OSCC progression, chemoresistance and invasion. Positive correlations were observed, mainly between the expression of CD44v4 and the activation of ERK1/2 causing chemoresistance, whereas CD44v6 expression and inactivation of GSK3β caused invasiveness of OSCC. Cisplatin resistant, CisR-SCC9/SCC4 cell lines showed OCSC properties. Inhibition of MEK/ERK1/2 by SMI or knock down (KD) of CD44v4 by siRNA reversed cisplatin-resistance, whereas blocking the PI3K/Akt/GSK3β pathway by SMI or KD of CD44v6 isoforms by respective siRNA diminished invasion/metastasis potential. Collectively, our results demonstrated that CD44v4 expression is more linked with ERK1/2 activation and promote cisplatin resistance, whereas CD44v6 expression is associated primarily with PI3K/Akt/GSK3β activation and driving tumor invasion/migration.