thymosin-beta(4) and Cell-Transformation--Neoplastic

Thymosin β4 (Tβ4), a 5 kDa protein, has been demonstrated to play an important role in a variety of biological activities, such as actin sequestering, cellular motility, migration, inflammation, and damage repair. Recently, several novel findings provided compelling evidence that Tβ4 played a key role in facilitating tumor metastasis and angiogenesis. It has been found that Tβ4 expressed increasingly in a number of metastatic tumors, which was associated with an increased expression of a known angiogenic factor, vascular endothelial growth factor. Thus, Tβ4 provided a potential target of opportunity for cancer management, especially for cancer metastasis therapy.

Topics: Animals; Cell Movement; Cell Survival; Cell Transformation, Neoplastic; Drug Resistance, Neoplasm; Epithelial-Mesenchymal Transition; Gene Expression Regulation, Neoplastic; Humans; Inflammation; Neoplasm Metastasis; Neoplastic Stem Cells; Neovascularization, Pathologic; Thymosin; Wound Healing

Male breast cancer comprises less than 1% of breast cancer diagnoses. Although estrogen exposure has been causally linked to the development of female breast cancers, the etiology of male breast cancer is unclear. Here, we show via fluorescence in situ hybridization (FISH) and droplet digital PCR (ddPCR) that the Y chromosome was clonally lost at a frequency of ~16% (5/31) in two independent cohorts of male breast cancer patients. We also show somatic loss of the Y chromosome gene TMSB4Y in a male breast tumor, confirming prior reports of loss at this locus in male breast cancers. To further understand the function of TMSB4Y, we created inducible cell lines of TMSB4Y in the female human breast epithelial cell line MCF-10A. Expression of TMSB4Y resulted in aberrant cellular morphology and reduced cell proliferation, with a corresponding reduction in the fraction of metaphase cells. We further show that TMSB4Y interacts directly with β-actin, the main component of the actin cytoskeleton and a cell cycle modulator. Taken together, our results suggest that clonal loss of the Y chromosome may contribute to male breast carcinogenesis, and that the TMSB4Y gene has tumor suppressor properties.

Topics: Actins; Breast Neoplasms, Male; Cell Line; Cell Proliferation; Cell Shape; Cell Transformation, Neoplastic; Chromosomes, Human, Y; Female; Gene Deletion; Gene Expression Regulation, Neoplastic; Humans; In Situ Hybridization, Fluorescence; Male; Mammary Glands, Human; Phenotype; Polymerase Chain Reaction; Thymosin; Time Factors; Transfection; Tumor Suppressor Proteins

Thymosin beta-4 (Tβ4) is known to be involved in tumorigenesis. Overexpression of this polypeptide has been observed in a wide variety of cancers, including colorectal carcinoma (CRC). Accordingly, Tβ4 has been proposed to be a novel therapeutic target for CRC, especially in its metastatic form. Although in vitro tumor-suppressive effects of Tβ4 gene silencing mediated by small hairpin RNA (shRNA) have already been demonstrated, the in vivo efficacy of such an approach has not yet been reported. Herein, we demonstrated that infection with recombinant adenovirus expressing an shRNA targeting Tβ4 markedly reduced the growth of and robustly induced apoptosis in CT-26 mouse CRC cells in culture. Additionally, tumors grown in nude mice from the CT-26 cells whose Tβ4 expression already been downregulated by virus infection were also drastically reduced. Most importantly, significant growth arrest of tumors derived from the parental CT-26 cells was observed after multiple intratumoral injections of these viruses. Together, our results show for the first time that in vivo silencing of Tβ4 expression by its shRNA generated after adenoviral infection can suppress CRC growth. These results further demonstrate the feasibility of treating CRC by a Tβ4 knockdown gene therapeutic approach.

Topics: Actins; Adenoviridae; Animals; Apoptosis; Cell Cycle; Cell Line, Tumor; Cell Transformation, Neoplastic; Colorectal Neoplasms; Disease Models, Animal; Gene Knockout Techniques; Genetic Vectors; Humans; Mice; RNA Interference; RNA, Messenger; RNA, Small Interfering; Thymosin; Transduction, Genetic; Tumor Burden; Xenograft Model Antitumor Assays

Thymosin β 4 (Tβ(4)) is a ubiquitous peptide that plays pivotal roles in the cytoskeletal system and in cell differentiation during embryogenesis. Recently, a role for Tβ(4) has been proposed in experimental and human carcinogenesis. This study was aimed at evaluating the correlation between Tβ(4) immunoractivity and colorectal cancer, with particular attemption to tumor cells undergoing epithelial-mesenchymal transition.. 86 intestinal biopsies were retrospectively analyzed including 76 colorectal adenocarcinomas with evident features of epithelial-mesenchymal transition, and 10 samples of normal colorectal mucosa. Paraffin sections were immunostained for Tβ(4) and for E-cadherin. Total RNA was isolated from frozen specimens obtained, at surgery, from the normal colon mucosa, the deeper regions and the superficial tumor regions in four cases of colon cancer. Tβ(4) immunoreactivity was detected in the vast majority (59/76) of colon carcinomas, showing a patchy distribution, with well differentiated areas significantly more reactive than the less differentiated tumor zones. We also noted a zonal pattern in the majority of tumors, characterized by a progressive increase in immunostaining for Tβ(4) from the superficial toward the deepest tumor regions. The strongest expression for Tβ(4) was frequently detected in invading tumor cells with features of epithelial-mesenchymal transition. The increase in reactivity for Tβ(4) matched with a progressive decrease in E-cadherin expression in invading cancer cells. At mRNA level, the differences in Tβ(4) expression between the surrounding colon mucosa and the tumors samples were not significant.. Our data show that Tβ(4) is expressed in the majority of colon cancers, with preferential immunoreactivity in deep tumor regions. The preferential expression of the peptide and the increase in intensity of the immunostaining at the invasion front suggests a possible link between the peptide and the process of epithelial mesenchymal transition, suggesting a role for Tβ(4) in colorectal cancer invasion and metastasis.

Topics: Adenocarcinoma; Cadherins; Cell Differentiation; Cell Line, Tumor; Cell Transformation, Neoplastic; Cohort Studies; Colorectal Neoplasms; Epithelial-Mesenchymal Transition; Humans; Immunohistochemistry; Thymosin

Nanoparticles are prevalent in both commercial and medicinal products; however, the contribution of nanomaterials to carcinogenesis remains unclear. We therefore examined the effects of nano-sized titanium dioxide (TiO(2)) on poorly tumorigenic and nonmetastatic QR-32 fibrosarcoma cells. We found that mice that were cotransplanted subcutaneously with QR-32 cells and nano-sized TiO(2), either uncoated (TiO(2)-1, hydrophilic) or coated with stearic acid (TiO(2)-2, hydrophobic), did not form tumors. However, QR-32 cells became tumorigenic after injection into sites previously implanted with TiO(2)-1, but not TiO(2)-2, and these developing tumors acquired metastatic phenotypes. No differences were observed either histologically or in inflammatory cytokine mRNA expression between TiO(2)-1 and TiO(2)-2 treatments. However, TiO(2)-2, but not TiO(2)-1, generated high levels of reactive oxygen species (ROS) in cell-free conditions. Although both TiO(2)-1 and TiO(2)-2 resulted in intracellular ROS formation, TiO(2)-2 elicited a stronger response, resulting in cytotoxicity to the QR-32 cells. Moreover, TiO(2)-2, but not TiO(2)-1, led to the development of nuclear interstices and multinucleate cells. Cells that survived the TiO(2) toxicity acquired a tumorigenic phenotype. TiO(2)-induced ROS formation and its related cell injury were inhibited by the addition of antioxidant N-acetyl-l-cysteine. These results indicate that nano-sized TiO(2) has the potential to convert benign tumor cells into malignant ones through the generation of ROS in the target cells.

Topics: 8-Hydroxy-2'-Deoxyguanosine; Animals; Cell Line, Tumor; Cell Transformation, Neoplastic; Cytokines; Deoxyguanosine; Dinoprostone; Female; Fibrosarcoma; Intercellular Signaling Peptides and Proteins; Mice; Mice, Inbred C57BL; Nanoparticles; Neoplasm Invasiveness; Particle Size; Reactive Oxygen Species; Thymosin; Titanium; Vascular Endothelial Growth Factor A

S-adenosylmethionine decarboxylase (AdoMetDC) is a key enzyme in the synthesis of polyamines essential for cell growth and proliferation. Its overexpression induces the transformation of murine fibroblasts in both sense and antisense orientations, yielding highly invasive tumors in nude mice. These cell lines hence provide a good model to study cell invasion. Here, the gene expression profiles of these cells were compared with their normal counterpart by microarray analyses (Incyte Genomics, Palo Alto, CA, and Affymetrix, Santa Clara, CA). Up-regulation of the actin sequestering molecule thymosin beta4 was the most prominent change in both cell lines. Tetracycline-inducible expression of thymosin beta4 antisense RNA caused a partial reversal of the transformed phenotype. Further, reversal of transformation by dominant-negative mutant of c-Jun (TAM67) caused reduction in thymosin beta4 mRNA. Interestingly, a sponge toxin, latrunculin A, which inhibits the binding of thymosin beta4 to actin, was found to profoundly affect the morphology and proliferation of the AdoMetDC transformants and to block their invasion in three-dimensional Matrigel. Thus, thymosin beta4 is a determinant of AdoMetDC-induced transformed phenotype and invasiveness. Up-regulation of thymosin beta4 was also found in ras-transformed fibroblasts and metastatic human melanoma cells. These data encourage testing latrunculin A-like and other agents interfering with thymosin beta4 for treatment of thymosin beta4-overexpressing tumors with high invasive and metastatic potential.

Topics: Adenosylmethionine Decarboxylase; Animals; Cell Transformation, Neoplastic; Fibroblasts; Gene Expression Profiling; Humans; Melanoma; Mice; Neoplasm Invasiveness; Oligonucleotide Array Sequence Analysis; Phenotype; Skin Neoplasms; Thymosin; Up-Regulation

Topics: Actins; Animals; Antineoplastic Agents; Cell Physiological Phenomena; Cell Transformation, Neoplastic; Humans; Male; Melanoma, Experimental; Neoplasm Metastasis; Neovascularization, Pathologic; Prostatic Neoplasms; Thymosin; Up-Regulation