Spontaneous activity of the mitochondrial apoptosis pathway drives chromosomal defects, the appearance of micronuclei and cancer metastasis through the Caspase-Activated DNAse.

Micronuclei are DNA-containing structures separate from the nucleus found in cancer cells. Micronuclei are recognized by the immune sensor axis cGAS/STING, driving cancer metastasis. The mitochondrial apoptosis apparatus can be experimentally triggered to a non-apoptotic level, and this can drive the appearance of micronuclei through the Caspase-activated DNAse (CAD). We tested whether spontaneously appearing micronuclei in cancer cells are linked to sub-lethal apoptotic signals. Inhibition of mitochondrial apoptosis or of CAD reduced the number of micronuclei in tumor cell lines as well as the number of chromosomal misalignments in tumor cells and intestinal organoids. Blockade of mitochondrial apoptosis or deletion of CAD reduced, while experimental activation CAD, STING-dependently, enhanced aggressive growth of tumor cells in vitro. Deletion of CAD from human cancer cells reduced metastasis in xenograft models. CAD-deficient cells displayed a substantially altered gene-expression profile, and a CAD-associated gene expression 'signature' strongly predicted survival in cancer patients. Thus, low-level activity in the mitochondrial apoptosis apparatus operates through CAD-dependent gene-induction and STING-activation and has substantial impact on metastasis in cancer.

Unusual Manifestation of Chronic Lymphocytic Leukemia in the Hand.

Chronic lymphocytic leukemia (CLL) involving the hand, especially with bone involvement, is extremely rare. We report a case of a 62-year-old man, with a 4-year history of a subclinical CLL, presenting with chronic swelling and pain over the dorsal surface of the right hand, mimicking an infectious process. There was no clinical response to broad-spectrum antibiotics and topical corticosteroid therapy. Imaging was inconclusive. A tissue biopsy revealed a manifestation of the underlying leukemia. This case highlights the need to consider uncommon etiologies for atypical clinical presentations.