Sox2 Is an Oncogenic Driver of Small-Cell Lung Cancer and Promotes the Classic Neuroendocrine Subtype.

Although many cancer prognoses have improved in the past 50 years due to advancements in treatments, there has been little improvement in therapies for small-cell lung cancer (SCLC). One promising avenue to improve treatment for SCLC is to understand its underlying genetic alterations that drive its formation, growth, and cellular heterogeneity. RB1 loss is one key driver of SCLC, and RB1 loss has been associated with an increase in pluripotency factors such as SOX2. SOX2 is highly expressed and amplified in SCLC and has been associated with SCLC growth. Using a genetically engineered mouse model, we have shown that Sox2 is required for efficient SCLC formation. Furthermore, genome-scale binding assays have indicated that SOX2 can regulate key SCLC pathways such as NEUROD1 and MYC. These data suggest that SOX2 can be associated with the switch of SCLC from an ASCL1 subtype to a NEUROD1 subtype. Understanding this genetic switch is key to understanding such processes as SCLC progression, cellular heterogeneity, and treatment resistance. IMPLICATIONS: Understanding the molecular mechanisms of SCLC initiation and development are key to opening new potential therapeutic options for this devastating disease.

DCLK1 Regulates Tumor Stemness and Cisplatin Resistance in Non-small Cell Lung Cancer via ABCD-Member-4.

Chemoresistance cells have features similar to cancer stem cells. Elimination of these cells is an effective therapeutic strategy to clinically combat chemoresistance non-small cell lung cancer (NSCLC). Here, we demonstrate that Doublecortin-like kinase1 (DCLK1) is the key to developing chemoresistance and associated stemness in NSCLC. DCLK1 is highly expressed in human lung adenocarcinoma and strongly correlated with stemness. Silencing DCLK1 inhibits NSCLC cell primary and secondary spheroid formation, which is the prerequisite feature of tumor stem cells. DCLK1 inhibition reduced NSCLC cell migration/invasion in vitro and induced tumor growth inhibition in vivo. NSCLC cells responded differently to cisplatin treatment; indeed, the clonogenic ability of all NSCLC cells was reduced. We found that the cisplatin-resistant NSCLC cells gain the expression of DCLK1 compared with their parental control. However, DCLK1 inhibition in cisplatin-resistance NSCLC cells reverses the tumor cell resistance to cisplatin and reduced tumor self-renewal ability. Specifically, we found that DCLK1-mediated cisplatin resistance in NSCLC is via an ABC subfamily member 4 (ABCD4)-dependent mechanism. Our data demonstrate that increased expression of DCLK1 is associated with chemoresistance and enhanced cancer stem cell-like features in NSCLC. Targeting DCLK1 using gene knockdown/knockout strategies alone or in combination with cisplatin may represent a novel therapeutic strategy to treat NSCLC.

Complete Genome Sequences of Three Novel Pseudomonas fluorescens SBW25 Bacteriophages, Noxifer, Phabio, and Skulduggery.

Three novel bacteriophages, two of which are jumbophages, were isolated from compost in Auckland, New Zealand. Noxifer, Phabio, and Skulduggery are double-stranded DNA (dsDNA) phages with genome sizes of 278,136 bp (Noxifer), 309,157 bp (Phabio), and 62,978 bp (Skulduggery).