Piezo2 channel regulates RhoA and actin cytoskeleton to promote cell mechanobiological responses

Actin polymerization and assembly into stress fibers (SFs) is central to many cellular processes. However, how SFs form in response to the mechanical interaction of cells with their environment is not fully understood. Here we have identified Piezo2 mechanosensitive cationic channel as a transducer of environmental physical cues into mechanobiological responses. Piezo2 is needed by brain metastatic cells from breast cancer (MDA-MB-231-BrM2) to probe their physical environment as they anchor and pull on their surroundings or when confronted with confined migration through narrow pores. Piezo2-mediated Ca2+ influx activates RhoA to control the formation and orientation of SFs and focal adhesions (FAs). A possible mechanism for the Piezo2-mediated activation of RhoA involves the recruitment of the Fyn kinase to the cell leading edge as well as calpain activation. Knockdown of Piezo2 in BrM2 cells alters SFs, FAs, and nuclear translocation of YAP; a phenotype rescued by overexpression of dominant-positive RhoA or its downstream effector, mDia1. Consequently, hallmarks of cancer invasion and metastasis related to RhoA, actin cytoskeleton, and/or force transmission, such as migration, extracellular matrix degradation, and Serpin B2 secretion, were reduced in cells lacking Piezo2

Mantle-cell lymphoma genotypes identified with CGH to BAC microarrays define a leukemic subgroup of disease and predict patient outcome

To identify recurrent genomic changes in mantle cell lymphoma (MCL), we used high-resolution comparative genomic hybridization (CGH) to bacterial artificial chromosome (BAC) microarrays in 68 patients and 9 MCL-derived cell lines. Array CGH defined an MCL genomic signature distinct from other B-cell lymphomas, including deletions of 1p21 and 11q22.3-ATM gene with coincident 10p12-BMI1 gene amplification and 10p14 deletion, along with a previously unidentified loss within 9q21-q22. Specific genomic alterations were associated with different subgroups of disease. Notably, 11 patients with leukemic MCL showed a different genomic profile than nodal cases, including 8p21.3 deletion at tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene cluster (55% versus 19%; P = .01) and gain of 8q24.1 at MYC locus (46% versus 14%; P = .015). Additionally, leukemic MCL exhibited frequent IGVH mutation (64% versus 21%; P = .009) with preferential VH4-39 use (36% versus 4%; P = .005) and followed a more indolent clinical course. Blastoid variants, increased number of genomic gains, and deletions of P16/INK4a and TP53 genes correlated with poorer outcomes, while 1p21 loss was associated with prolonged survival (P = .02). In multivariate analysis, deletion of 9q21-q22 was the strongest predictor for inferior survival (hazard ratio [HR], 6; confidence interval [CI], 2.3 to 15.7). Our study highlights the genomic profile as a predictor for clinical outcome and suggests that "genome scanning" of chromosomes 1p21, 9q21-q22, 9p21.3-P16/INK4a, and 17p13.1-TP53 may be clinically useful in MCL

Characterization of 8p21.3 chromosomal deletions in B-cell lymphoma: TRAIL-R1 and TRAIL-R2 as candidate dosage-dependent tumor suppressor genes

Deletions of chromosome 8p are a recurrent event in B-cell non-Hodgkin lymphoma (B-NHL), suggesting the presence of a tumor suppressor gene. We have characterized these deletions using comparative genomic hybridization to microarrays, fluorescence in situ hybridization (FISH) mapping, DNA sequencing, and functional studies. A minimal deleted region (MDR) of 600 kb was defined in chromosome 8p21.3, with one mantle cell lymphoma cell line (Z138) exhibiting monoallelic deletion of 650 kb. The MDR extended from bacterial artificial chromosome (BAC) clones RP11-382J24 and RP11-109B10 and included the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene loci. Sequence analysis of the individual expressed genes within the MDR and DNA sequencing of the entire MDR in Z138 did not reveal any mutation. Gene expression analysis and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) showed down-regulation of TRAIL-R1 and TRAIL-R2 receptor genes as a consistent event in B-NHL with 8p21.3 loss. Epigenetic inactivation was excluded via promoter methylation analysis. In vitro studies showed that TRAIL-induced apoptosis was dependent on TRAIL-R1 and/or -R2 dosage in most tumors. Resistance to apoptosis of cell lines with 8p21.3 deletion was reversed by restoration of TRAIL-R1 or TRAIL-R2 expression by gene transfection. Our data suggest that TRAIL-R1 and TRAIL-R2 act as dosage-dependent tumor suppressor genes whose monoallelic deletion can impair TRAIL-induced apoptosis in B-cell lymphoma

Homozygous deletions localize novel tumor suppressor genes in B-cell lymphomas

Integrative genomic and gene-expression analyses have identified amplified oncogenes in B-cell non-Hodgkin lymphoma (B-NHL), but the capability of such technologies to localize tumor suppressor genes within homozygous deletions remains unexplored. Array-based comparative genomic hybridization (CGH) and gene-expression microarray analysis of 48 cell lines derived from patients with different B-NHLs delineated 20 homozygous deletions at 7 chromosome areas, all of which contained tumor suppressor gene targets. Further investigation revealed that only a fraction of primary biopsies presented inactivation of these genes by point mutation or intragenic deletion, but instead some of them were frequently silenced by epigenetic mechanisms. Notably, the pattern of genetic and epigenetic inactivation differed among B-NHL subtypes. Thus, the P53-inducible PIG7/LITAF was silenced by homozygous deletion in primary mediastinal B-cell lymphoma and by promoter hypermethylation in germinal center lymphoma, the proapoptotic BIM gene presented homozygous deletion in mantle cell lymphoma and promoter hypermethylation in Burkitt lymphoma, the proapoptotic BH3-only NOXA was mutated and preferentially silenced in diffuse large B-cell lymphoma, and INK4c/P18 was silenced by biallelic mutation in mantle-cell lymphoma. Our microarray strategy has identified novel candidate tumor suppressor genes inactivated by genetic and epigenetic mechanisms that substantially vary among the B-NHL subtypes

Mantle-cell lymphoma genotypes identified with CGH to BAC microarrays define a leukemic subgroup of disease and predict patient outcome

To identify recurrent genomic changes in mantle cell lymphoma (MCL), we used high-resolution comparative genomic hybridization (CGH) to bacterial artificial chromosome (BAC) microarrays in 68 patients and 9 MCL-derived cell lines. Array CGH defined an MCL genomic signature distinct from other B-cell lymphomas, including deletions of 1p21 and 11q22.3-ATM gene with coincident 10p12-BMI1 gene amplification and 10p14 deletion, along with a previously unidentified loss within 9q21-q22. Specific genomic alterations were associated with different subgroups of disease. Notably, 11 patients with leukemic MCL showed a different genomic profile than nodal cases, including 8p21.3 deletion at tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene cluster (55% versus 19%; P = .01) and gain of 8q24.1 at MYC locus (46% versus 14%; P = .015). Additionally, leukemic MCL exhibited frequent IGVH mutation (64% versus 21%; P = .009) with preferential VH4-39 use (36% versus 4%; P = .005) and followed a more indolent clinical course. Blastoid variants, increased number of genomic gains, and deletions of P16/INK4a and TP53 genes correlated with poorer outcomes, while 1p21 loss was associated with prolonged survival (P = .02). In multivariate analysis, deletion of 9q21-q22 was the strongest predictor for inferior survival (hazard ratio [HR], 6; confidence interval [CI], 2.3 to 15.7). Our study highlights the genomic profile as a predictor for clinical outcome and suggests that "genome scanning" of chromosomes 1p21, 9q21-q22, 9p21.3-P16/INK4a, and 17p13.1-TP53 may be clinically useful in MCL

Characterization of 8p21.3 chromosomal deletions in B-cell lymphoma: TRAIL-R1 and TRAIL-R2 as candidate dosage-dependent tumor suppressor genes

Deletions of chromosome 8p are a recurrent event in B-cell non-Hodgkin lymphoma (B-NHL), suggesting the presence of a tumor suppressor gene. We have characterized these deletions using comparative genomic hybridization to microarrays, fluorescence in situ hybridization (FISH) mapping, DNA sequencing, and functional studies. A minimal deleted region (MDR) of 600 kb was defined in chromosome 8p21.3, with one mantle cell lymphoma cell line (Z138) exhibiting monoallelic deletion of 650 kb. The MDR extended from bacterial artificial chromosome (BAC) clones RP11-382J24 and RP11-109B10 and included the tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) receptor gene loci. Sequence analysis of the individual expressed genes within the MDR and DNA sequencing of the entire MDR in Z138 did not reveal any mutation. Gene expression analysis and quantitative reverse transcriptase-polymerase chain reaction (QRT-PCR) showed down-regulation of TRAIL-R1 and TRAIL-R2 receptor genes as a consistent event in B-NHL with 8p21.3 loss. Epigenetic inactivation was excluded via promoter methylation analysis. In vitro studies showed that TRAIL-induced apoptosis was dependent on TRAIL-R1 and/or -R2 dosage in most tumors. Resistance to apoptosis of cell lines with 8p21.3 deletion was reversed by restoration of TRAIL-R1 or TRAIL-R2 expression by gene transfection. Our data suggest that TRAIL-R1 and TRAIL-R2 act as dosage-dependent tumor suppressor genes whose monoallelic deletion can impair TRAIL-induced apoptosis in B-cell lymphoma

Homozygous deletions localize novel tumor suppressor genes in B-cell lymphomas

Integrative genomic and gene-expression analyses have identified amplified oncogenes in B-cell non-Hodgkin lymphoma (B-NHL), but the capability of such technologies to localize tumor suppressor genes within homozygous deletions remains unexplored. Array-based comparative genomic hybridization (CGH) and gene-expression microarray analysis of 48 cell lines derived from patients with different B-NHLs delineated 20 homozygous deletions at 7 chromosome areas, all of which contained tumor suppressor gene targets. Further investigation revealed that only a fraction of primary biopsies presented inactivation of these genes by point mutation or intragenic deletion, but instead some of them were frequently silenced by epigenetic mechanisms. Notably, the pattern of genetic and epigenetic inactivation differed among B-NHL subtypes. Thus, the P53-inducible PIG7/LITAF was silenced by homozygous deletion in primary mediastinal B-cell lymphoma and by promoter hypermethylation in germinal center lymphoma, the proapoptotic BIM gene presented homozygous deletion in mantle cell lymphoma and promoter hypermethylation in Burkitt lymphoma, the proapoptotic BH3-only NOXA was mutated and preferentially silenced in diffuse large B-cell lymphoma, and INK4c/P18 was silenced by biallelic mutation in mantle-cell lymphoma. Our microarray strategy has identified novel candidate tumor suppressor genes inactivated by genetic and epigenetic mechanisms that substantially vary among the B-NHL subtypes