Resistance to ATR Inhibitors Is Mediated by Loss of the Nonsense-Mediated Decay Factor UPF2.

Unlabelled: Over one million cases of gastric cancer are diagnosed each year globally, and the metastatic disease continues to have a poor prognosis. A significant proportion of gastric tumors have defects in the DNA damage response pathway, creating therapeutic opportunities through synthetic lethal approaches. Several small-molecule inhibitors of ATR, a key regulator of the DNA damage response, are now in clinical development as targeted agents for gastric cancer.

BRAF induces reversible mitotic arrest in human melanocytes via microrna-mediated suppression of AURKB.

Benign melanocytic nevi frequently emerge when an acquired mutation triggers unchecked proliferation and subsequent arrest in melanocytes. Recent observations have challenged the role of oncogene-induced senescence in melanocytic nevus formation, necessitating investigations into alternative mechanisms for the establishment and maintenance of proliferation arrest in nevi. We compared the transcriptomes of melanocytes from healthy human skin, nevi, and melanomas arising from nevi and identified a set of microRNAs as highly expressed nevus-enriched transcripts.

Bi-allelic Loss of CDKN2A Initiates Melanoma Invasion via BRN2 Activation.

Loss of the CDKN2A tumor suppressor is associated with melanoma metastasis, but the mechanisms connecting the phenomena are unknown. Using CRISPR-Cas9 to engineer a cellular model of melanoma initiation from primary human melanocytes, we discovered that a lineage-restricted transcription factor, BRN2, is downstream of CDKN2A and directly regulated by E2F1. In a cohort of melanocytic tumors that capture distinct progression stages, we observed that CDKN2A loss coincides with both the onset of invasive behavior and increased BRN2 expression.

Cooperativity Enables Non-neutralizing Antibodies to Neutralize Ebolavirus.

Drug combinations are synergistic when their combined efficacy exceeds the sum of the individual actions, but they rarely include ineffective drugs that become effective only in combination. We identified several "enabling pairs" of neutralizing and non-neutralizing anti-ebolavirus monoclonal antibodies, whose combination exhibited new functional profiles, including transforming a non-neutralizing antibody to a neutralizer. Sub-neutralizing concentrations of antibodies 2G4 or m8C4 enabled non-neutralizing antibody FVM09 (IC >1 μM) to exhibit potent neutralization (IC 1-10 nM).

Selective Vulnerability of Cancer Cells by Inhibition of Ca(2+) Transfer from Endoplasmic Reticulum to Mitochondria.

In the absence of low-level ER-to-mitochondrial Ca(2+) transfer, ATP levels fall, and AMPK-dependent, mTOR-independent autophagy is induced as an essential survival mechanism in many cell types. Here, we demonstrate that tumorigenic cancer cell lines, transformed primary human fibroblasts, and tumors in vivo respond similarly but that autophagy is insufficient for survival, and cancer cells die while their normal counterparts are spared. Cancer cell death is due to compromised bioenergetics that can be rescued with metabolic substrates or nucleotides and caused by necrosis associated with mitotic catastrophe during their proliferation.

CDKN2B Loss Promotes Progression from Benign Melanocytic Nevus to Melanoma.

Unlabelled: Deletion of the entire CDKN2B-CDKN2A gene cluster is among the most common genetic events in cancer. The tumor-promoting effects are generally attributed to loss of CDKN2A-encoded p16 and p14ARF tumor suppressors. The degree to which the associated CDKN2B-encoded p15 loss contributes to human tumorigenesis is unclear.

IQGAP1 and IQGAP3 Serve Individually Essential Roles in Normal Epidermal Homeostasis and Tumor Progression.

IQ motif-containing GTPase-activating protein (IQGAP) scaffolding proteins regulate many essential cellular processes including growth factor receptor signaling, cytoskeletal rearrangement, adhesion, and proliferation and are highly expressed in many cancers. Using genetically engineered human skin tissue in vivo, we demonstrate that diminished, sub-physiologic expression of IQGAP1 or IQGAP3 is sufficient to maintain normal epidermal homeostasis, whereas significantly higher levels are required to support tumorigenesis. To target this tumor-specific IQGAP requirement in vivo, we engineered epidermal keratinocytes to express individual IQGAP protein domains designed to compete with endogenous IQGAPs for effector protein binding.

Activating FGFR3 mutations cause mild hyperplasia in human skin, but are insufficient to drive benign or malignant skin tumors.

Fibroblast growth factor receptor 3 (FGFR3) activating mutations are drivers of malignancy in several human tissues, including bladder, lung, cervix, and blood. However, in skin, these mutations are associated predominantly with benign, common epidermal growths called seborrheic keratoses (SKs). How epidermis resists FGFR3 mediated transformation is unclear, but previous studies have suggested that FGFR3 activation in skin keratinocytes may serve a tumor-suppressive role by driving differentiation and antagonizing Ras signaling.