Hyaluronan-CD44 Interaction with Leukemia-associated RhoGEF and Epidermal Growth Factor Receptor Promotes Rho/Ras Co-activation, Phospholipase Cϵ-Ca2+ Signaling, and Cytoskeleton Modification in Head and Neck Squamous Cell Carcinoma Cells

Abstract

In this study we have examined the interaction of CD44 (a major hyaluronan (HA) receptor) with a RhoA-specific guanine nucleotide exchange factor (leukemia-associated RhoGEF (LARG)) in human head and neck squamous carcinoma cells (HNSCC- Human head and neck squamous cell carcinoma (HNSCC) 2 is a very malignant cancer associated with major morbidity and mortality. This deadly disease includes cancers of the lips, oral cavity, pharynx, hypopharynx, larynx, nose, nasal, sinuses, neck, ears, and salivary glands (1-6). Approximately 90% of HNSCCs are very aggressive and rapidly invade the surrounding tissues. Because little is known about the molecular basis underlying the progression of HNSCC to the invasive phenotype, it is very difficult to predict individual tumor aggressiveness and to design effective treatment plans. Thus, there is currently a great need to clarify those aspects of tumor formation underlying the clinical behavior of HNSCC.HSCA number of studies have aimed at identifying the specific molecules expressed in HNSCC that correlate with invasive behavior. Among such candidates are hyaluronan (HA) (7, 8) and its major cell surface receptor, CD44 (9). HA is a major component of the extracellular matrix component and is significantly enriched in many types of tumors (7,8). HA binds to its specific cell surface receptor, CD44, a multifunctional transmembrane glycoprotein expressed in many cells and tissues including HNSCC cells and carcinoma tissues (10 -14). CD44 is often expressed as a variety of variant isoforms, generated by an alternative splicing mechanism (15). The expression of certain CD44 variant (CD44v) isoforms is known to be associated with head and neck cancer progression (10 -14).The external portion of CD44 binds HA (9), whereas the intracellular domain interacts with specific signaling molecules such as RhoA-activated Rho kinase (16) and Rho/Rac1-specific guanine nucleotide exchange factors (p115RhoGEF (17), Tiam1 (18), and Vav2 (19)), c-Src kinase (20), protein kinase N␥ (21), IQGAP1 (22), p185 HER2 (23), and transforming growth factor-␤ receptors (24)). CD44 also binds directly to cytoskeletal proteins such as ankyrin and ezrin, radixin, and moesin (25-28). The interaction of CD44 with the cytoskeleton and various signaling molecules plays a pivotal role in promoting metastatic-specific tumor phenotypes such as matrix metalloproteinase (MMP)-mediated matrix degradation, tumor cell growth, migration, and invasion (10, 16 -28 2 The abbreviations used are: HNSCC, human head and neck squamous cell carcinoma; ERK, extracellular signal-regulated kinase; MAPK, mitogen-activated protein kinase; HA, hyaluronan; MMP, matrix metalloproteinase; EGFR, epidermal growth factor (EGF) receptor; GEF, guanine nucleotide exchange factor; LARG, leukemia-associated RhoGEF; DH, dbl homology; PH, pleckstrin homology; PLC, phospholipase C; IP 3 , inositol 1,4,5-triphosphate; CaMKII, Ca 2ϩ /calmodulin-dependent kinase II; GST, glutathione S-transferase; FITC, fluorescein isothiocyanate; BSA, bovine serum alb...

Association of Genetic Polymorphisms at 1q22 but not 10q23 with Gastric Cancer in a Southern Chinese Population

“…SNP rs2274223 is localised to exon 26 of PLCE1, a member of the phospholipase C protein family that catalyses the hydrolysis of phosphatidylinositol-4, 5-bisphosphate to generate two intracellular signalling molecules: inositol 1,4,5-triphosphate (IP3) and diacylglycerol (DAG). This enzyme interacts with the proto-oncogene ras (Bunney et al, 2009); participates in the regulation of cell growth, differentiation, apoptosis, and angiogenesis in the skin (Bai et al, 2004); and is involved in intestinal carcinogenesis (Bourguignon et al, 2006). We found no significant association with the SNPs at 10q23, which suggests a genetic difference between this Chinese population and others.…”

Effects of PLCE1 Gene Silencing by RNA Interference on Cell Cycling and Apoptosis in Esophageal Carcinoma Cells

“…PLCE1 showed significantly higher expression in esophageal carcinoma tissue. Some studies found that PLCE1 is correlated with the occurrence and development of gastric carcinoma (Luo et al, 2011), colorectal carcinoma (Danielsen et al, 2011), small intestine cancer (Li et al, 2009), head and neck squamous cell carcinoma (Bourguignon et al, 2006) and skin cancer (Bai et al, 2004).…”

Control of cell mechanics by RhoA and calcium fluxes during epithelial scattering

“…Filamin loosely crosslinks F-actin, causing the cytosol to become gel-like, an activity that must be antagonized to change cell morphology and increase motility. 92 Increasing cytosolic calcium in head and neck squamous cell carcinoma cells increases filamin phosphorylation and decreases filamin-actin associations, while adding the CaMKII inhibitor KN-93 returns both phosphorylation and actin binding to normal. 92 Spinophilin, which binds to and bundles F-actin, is also phosphorylated by CaMKII, reducing its affinity for Factin.…”

“…92 Increasing cytosolic calcium in head and neck squamous cell carcinoma cells increases filamin phosphorylation and decreases filamin-actin associations, while adding the CaMKII inhibitor KN-93 returns both phosphorylation and actin binding to normal. 92 Spinophilin, which binds to and bundles F-actin, is also phosphorylated by CaMKII, reducing its affinity for Factin. 93 In MDCK cells undergoing HGF-induced epithelial scattering, the resolution of larger actin cables into a transcellular network does appear to involve a reduction in bundling, as demonstrated by the loss of actin bundling protein a-actinin shortly after HGF stimulation and prior to actin cable dissolution into smaller filaments.…”