Cancer cells possess a broad spectrum of migration and invasion mechanisms. These include both individual and collective cell-migration strategies. Cancer therapeutics that are designed to target adhesion receptors or proteases have not proven to be effective in slowing tumour progression in clinical trials — this might be due to the fact that cancer cells can modify their migration mechanisms in response to different conditions. Learning more about the cellular and molecular basis of these different migration/invasion programmes will help us to understand how cancer cells disseminate and lead to new treatment strategies.

Tumour-cell invasion and migration: diversity and escape mechanisms

Alterations in cellular adhesion and apoptosis in epithelial cells overexpressing prostaglandin endoperoxide synthase 2

Nuclear factor (NF)-kappaB and inhibitor of NF-kappaB kinase (IKK) proteins regulate many physiological processes, including the innate- and adaptive-immune responses, cell death and inflammation. Disruption of NF-kappaB or IKK function contributes to many human diseases, including cancer. However, the NF-kappaB and IKK pathways do not exist in isolation and there are many mechanisms that integrate their activity with other cell-signalling networks. This crosstalk constitutes a decision-making process that determines the consequences of NF-kappaB and IKK activation and, ultimately, cell fate.

Integrating cell-signalling pathways with NF-kappaB and IKK function.

Since the initial discovery of the oncogenic activity of WNT1 in mouse mammary glands, our appreciation for the complex roles for WNT signalling pathways in cancer has increased dramatically. WNTs and their downstream effectors regulate various processes that are important for cancer progression, including tumour initiation, tumour growth, cell senescence, cell death, differentiation and metastasis. Although WNT signalling pathways have been difficult to target, improved drug-discovery platforms and new technologies have facilitated the discovery of agents that can alter WNT signalling in preclinical models, thus setting the stage for clinical trials in humans.

WNT signalling pathways as therapeutic targets in cancer

Cells within tissues are continuously exposed to physical forces including hydrostatic pressure, shear stress, and compression and tension forces. Cells dynamically adapt to force by modifying their behaviour and remodelling their microenvironment. They also sense these forces through mechanoreceptors and respond by exerting reciprocal actomyosin- and cytoskeletal-dependent cell-generated force by a process termed 'mechanoreciprocity'. Loss of mechanoreciprocity has been shown to promote the progression of disease, including cancer. Moreover, the mechanical properties of a tissue contribute to disease progression, compromise treatment and might also alter cancer risk. Thus, the changing force that cells experience needs to be considered when trying to understand the complex nature of tumorigenesis.

/pdf/a-tense-situation-forcing-tumour-progression-4myf9i89al.pdf

A Tense Situation: Forcing Tumour Progression

Sertoli cell preparations isolated from 10-day-old rats were cultured on three different substrates: plastic, a matrix deposited by co-culture of Sertoli and peritubular myoid cells, and a reconstituted basement membrane gel from the EHS tumor. When grown on plastic, Sertoli cells formed a squamous monolayer that did not retain contaminating germ cells. Grown on the matrix deposited by Sertoli-myoid cell co-cultures, Sertoli cells were more cuboidal and supported some germ cells but did not allow them to differentiate. After 3 wk however, the Sertoli cells flattened to resemble those grown on plastic. In contrast, the Sertoli cells grown on top of the reconstituted basement membrane formed polarized monolayers virtually identical to Sertoli cells in vivo. They were columnar with an elaborate cytoskeleton. In addition, they had characteristic basally located tight junctions and maintained germ cells for at least 5 wk in the basal aspect of the monolayer. However, germ cells did not differentiate. Total protein, androgen binding protein, transferrin, and type I collagen secretion were markedly greater when Sertoli cells were grown on the extracellular matrices than when they were grown on plastic. When Sertoli cells were cultured within rather than on top of reconstituted basement membrane gels they reorganized into cords. After one week, tight junctional complexes formed between adjacent Sertoli cells, functionally compartmentalizing the cords into central (adluminal) and peripheral (basal) compartments. Germ cells within the cords continued to differentiate. Thus, Sertoli cells cultured on top of extracellular matrix components assume a phenotype and morphology more characteristic of the in vivo, differentiated cells. Growing Sertoli cells within reconstituted basement membrane gels induces a morphogenesis of the cells into cords, which closely resemble the organ from which the cells were dissociated and which provide an environment permissive for germ cell differentiation.

/pdf/extracellular-matrix-regulates-sertoli-cell-differentiation-1swj9rntrn.pdf

Extracellular matrix regulates Sertoli cell differentiation, testicular cord formation, and germ cell development in vitro.

beta-Catenin is a multifunctional molecule with important roles in intercellular adhesion and signal transduction. We reported previously that beta-catenin is mutated in human prostate cancer. In this study, we investigated the role of beta-catenin mutations on androgen receptor (AR) signaling. beta-Catenin significantly enhanced androgen-stimulated transcriptional activation by the AR. beta-Catenin also increased AR transcriptional activation by androstenedione and estradiol and diminished the antagonism of bicalutamide. Coimmunoprecipitation of beta-catenin with AR from LNCaP prostate cancer cells showed that the two molecules are present in the same complex. The amount of beta-catenin in complex with AR was increased by androgen. These findings implicate beta-catenin in the regulation of AR function and support a role for beta-catenin mutations in the pathogenesis of prostate cancer.

https://cancerres.aacrjournals.org/content/canres/60/17/4709.full.pdf

β-Catenin Affects Androgen Receptor Transcriptional Activity and Ligand Specificity

https://aasldpubs.onlinelibrary.wiley.com/doi/pdf/10.1002/hep.22704

Liver stem cells and hepatocellular carcinoma

β-Catenin is an important regulator of cell–cell adhesion and embryonic development that associates with and regulates the function of the LEF/TCF family of transcription factors. Mutations of β-catenin and the tumor suppressor gene, adenomatous polyposis coli, occur in human cancers, but it is not known if, and by what mechanism, increased β-catenin causes cellular transformation. This study demonstrates that modest overexpression of β-catenin in a normal epithelial cell results in cellular transformation. These cells form colonies in soft agar, survive in suspension, and continue to proliferate at high cell density and following γ-irradiation. Endogenous cytoplasmic β-catenin levels and signaling activity were also found to oscillate during the cell cycle. Taken together, these data demonstrate that β-catenin functions as an oncogene by promoting the G1 to S phase transition and protecting cells from suspension-induced apoptosis (anoikis).

https://rupress.org/jcb/article-pdf/146/4/855/1286307/9812036.pdf

Exogenous expression of beta-catenin regulates contact inhibition, anchorage-independent growth, anoikis, and radiation-induced cell cycle arrest.

In several cancers, including breast cancer, loss of E-cadherin expression is correlated with a loss of the epithelial phenotype and with a gain of invasiveness. Cells that have lost E-cadherin expression are either poorly invasive with a rounded phenotype, or highly invasive, with a mesenchymal phenotype. Most cells lacking E-cadherin still retain weak calcium-dependent adhesion, indicating the presence of another cadherin family member. We have now examined the expression of the mesenchymal cadherin, cadherin-11, in breast cancer cell lines. Cadherin-11 mRNA and protein, as well as a variant form, are expressed in the most invasive cell lines but not in any of the noninvasive cell lines. Cadherin-11 is localized to a detergent-soluble pool and is associated with both α- and β-catenin. Immunocytochemistry shows that cadherin-11 is localized to the cell membrane at sites of cell-cell contact as well as at lamellipodia-like projections, which do not interact with other cells. These results suggest that cadherin-11 expression may be well correlated with the invasive phenotype in cancer cells and may serve as a molecular marker for the more aggressive, invasive subset of tumors. Cadherin-11 may mediate the interaction between malignant tumor cells and other cell types that normally express cadherin-11, such as stromal cells or osteoblasts or perhaps even with the surrounding extracellular matrix, thus facilitating tumor cell invasion and metastasis.

https://cancerres.aacrjournals.org/content/canres/59/4/947.full.pdf

Stephen W. Byers

Papers

Extracellular matrix regulates Sertoli cell differentiation, testicular cord formation, and germ cell development in vitro.

β-Catenin Affects Androgen Receptor Transcriptional Activity and Ligand Specificity

Liver stem cells and hepatocellular carcinoma

Exogenous expression of beta-catenin regulates contact inhibition, anchorage-independent growth, anoikis, and radiation-induced cell cycle arrest.

Cadherin-11 Is Expressed in Invasive Breast Cancer Cell Lines