Chrolactomycin

Examination of the metabolites produced by an Actinospica strain led to the identification of 6-hydroxychrolactomycin (compound 1), which is produced along with minor amounts of chrolactomycin (compound 2). The structure of 1 was established on the basis of extensive spectroscopic analysis, including one- and two-dimensional NMR. Compound 1 showed antimicrobial activity against Gram-positive bacteria, although it was generally less active than 2.

Beyond synthesizing telomere repeats, the telomerase reverse transcriptase (TERT) also serves multiple other roles supporting cancer growth. Blocking telomerase to drive telomere erosion appears impractical, but TERT's non-canonical activities have yet to be fully explored as cancer targets. Here, we used an irreversible TERT inhibitor, NU-1, to examine impacts on resistance to conventional cancer therapies. In vitro, inhibiting TERT sensitized cells to chemotherapy and radiation. NU-1 delayed repair of double-strand breaks, resulting in persistent DNA damage signaling and cellular senescence. Although NU-1 alone did not impact growth of syngeneic CT26 tumors in BALB/c mice, it dramatically enhanced the effects of radiation, leading to immune-dependent tumor elimination. Tumors displayed persistent DNA damage, suppressed proliferation, and increased activated immune infiltrate. Our studies confirm TERT's role in limiting genotoxic effects of conventional therapy but also implicate TERT as a determinant of immune evasion and therapy resistance.

Telomerase is a ribonuceloprotein complex responsible for maintaining telomeres and protecting chromosomal integrity. The human telomerase reverse transcriptase (hTERT) is expressed in ~90% of cancer cells where it confers the capacity for limitless proliferation. Along with its established role in telomere lengthening, telomerase also serves noncanonical extra-telomeric roles in oncogenic signaling, resistance to apoptosis, and enhanced DNA damage response. We report a new class of natural-product-inspired covalent inhibitors of telomerase that target the catalytic active site.