Oral Mucosal Organoids as a Potential Platform for Personalized Cancer Therapy.

Previous studies have described that tumor organoids can capture the diversity of defined human carcinoma types. Here, we describe conditions for long-term culture of human mucosal organoids. Using this protocol, a panel of 31 head and neck squamous cell carcinoma (HNSCC)-derived organoid lines was established.

Cryptochromes Interact Directly with PIFs to Control Plant Growth in Limiting Blue Light.

Sun-loving plants have the ability to detect and avoid shading through sensing of both blue and red light wavelengths. Higher plant cryptochromes (CRYs) control how plants modulate growth in response to changes in blue light. For growth under a canopy, where blue light is diminished, CRY1 and CRY2 perceive this change and respond by directly contacting two bHLH transcription factors, PIF4 and PIF5.

The kinase ABL phosphorylates the microprocessor subunit DGCR8 to stimulate primary microRNA processing in response to DNA damage.

The DNA damage response network stimulates microRNA (miRNA) biogenesis to coordinate repair, cell cycle checkpoints, and apoptosis. The multistep process of miRNA biogenesis involves the cleavage of primary miRNAs by the microprocessor complex composed of the ribonuclease Drosha and the RNA binding protein DGCR8. We found that the tyrosine kinase ABL phosphorylated DGCR8, a modification that was required for the induction of a subset of miRNAs after DNA damage.

Persistent inhibition of ABL tyrosine kinase causes enhanced apoptotic response to TRAIL and disrupts the pro-apoptotic effect of chloroquine.

TNF-Related Apoptosis Inducing Ligand (TRAIL) binds to and activates death receptors to stimulate caspase-8 and apoptosis with higher efficiency in cancer than normal cells but the development of apoptosis resistance has limited its clinical efficacy. We found that stable, but not transient knockdown of the ABL tyrosine kinase enhanced the apoptotic response to TRAIL. Re-expression of Abl, but not its nuclear import- or kinase-defective mutant, in the ABL-knockdown cells re-established apoptosis suppression.

Nuclear expression of β-catenin promotes RB stability and resistance to TNF-induced apoptosis in colon cancer cells.

Tumor necrosis factor (TNF)-α promotes tumor development under chronic inflammation. Because TNF also activates caspase-8, selective inhibition of TNF-induced extrinsic apoptosis would be required for inflammation-associated tumor growth. In a mouse model of inflammation-associated colon carcinogenesis, we found nuclear expression of β-catenin in tumors of wild-type, but not mutant, mice that were made resistant to TNF-induced apoptosis by a germline mutation blocking caspase cleavage of the retinoblastoma (RB) protein, despite similar frequencies of β-catenin exon-3 mutations in these two genetic backgrounds.

β-Catenin-dependent lysosomal targeting of internalized tumor necrosis factor-α suppresses caspase-8 activation in apoptosis-resistant colon cancer cells.

The Wnt/β-catenin pathway is constitutively activated in more than 90% of human colorectal cancer. Activated β-catenin stimulates cell proliferation and survival, however, its antiapoptotic mechanisms are not fully understood. We show here that activated β-catenin is required to suppress caspase-8 activation, but only in colon cancer cells that are resistant to tumor necrosis factor-α (TNF)-induced apoptosis.

Stress-induced ER to Golgi translocation of ceramide synthase 1 is dependent on proteasomal processing.

The ceramide synthase (CerS) enzymes are key regulators of ceramide homeostasis. CerS1 is central to regulating C18 ceramide which has been shown to be important in cancer and the response to chemotherapeutic drugs. Previous work indicated that some drugs induced a novel and specific translocation of CerS1 from the endoplasmic reticulum to the Golgi apparatus.

Ceramide synthase 1 is regulated by proteasomal mediated turnover.

Ceramide is an important bioactive lipid, intimately involved in many cellular functions, including the regulation of cell death, and in cancer and chemotherapy. Ceramide is synthesized de novo from sphinganine and acyl CoA via a family of 6 ceramide synthase enzymes, each having a unique preference for different fatty acyl CoA substrates and a unique tissue distribution. However, little is known regarding the regulation of these important enzymes.

Sensitive cell viability assay for use in drug screens and for studying the mechanism of action of drugs in Dictyostelium discoideum.

In order to increase the effectiveness of Dictyostelium discoideum as a lead genetic model for drug discovery, a luminescence-based assay has been adapted and standardized for sensitive and rapid cell viability measurements. The applicability of the assay was demonstrated by measuring the cytotoxicity of several drugs in wild-type and mutant cells. The robustness and ease of the assay demonstrate that it can be used in high-throughput applications such as drug or mutant screens.