Identification of targeted therapies for TNBC is an urgent medical need. Using a drug combination screen reliant on synthetic lethal interactions, we identified clinically relevant combination therapies for different TNBC subtypes. Two drug combinations targeting the BET family were further explored. The first, targeting BET and CXCR2, is specific for mesenchymal TNBC and induces apoptosis, whereas the second, targeting BET and the proteasome, is effective for major TNBC subtypes and triggers ferroptosis. Ferroptosis was induced at low drug doses and was associated with increased cellular iron and decreased glutathione levels, concomitant with reduced levels of GPX4 and key glutathione biosynthesis genes. Further functional studies, analysis of clinical datasets and breast cancer specimens revealed a unique vulnerability of TNBC to ferroptosis inducers, enrichment of ferroptosis gene signature, and differential expression of key proteins that increase labile iron and decrease glutathione levels. This study identified potent combination therapies for TNBC and unveiled ferroptosis as a promising therapeutic strategy.

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Rheumatoid arthritis (RA) is a chronic, autoimmune and inflammatory joint disease with a poorly understood etiology. Despite widespread diagnostic use of anti-citrullinated protein antibodies and rheumatoid factor proteins there is a strong demand for novel serological biomarkers to improve the diagnosis this disease. The present study was aimed to identify novel autoantigens involved in rheumatoid arthritis (RA) pathogenesis through immune-proteomic strategy. Synovial fluid samples from clinically diagnosed RA patients were separated on two-dimensional gel electrophoresis (2-DE). Samples from patients with non-RA rheumatisms (osteoarthritis and trauma) were used as controls. Immunoreactive proteins were spotted by Western blotting followed by identification through Q-TOF mass spectrometer analysis. Forty Western blots were generated using plasma from ten individual RA patients and 33 reactive spots were identified, 20 from the high molecular weight (HMW) gel and 13 from the low molecular weight (LMW) gel. Among the 33 common immunogenic spots, 18 distinct autoantigens were identified, out of which 14 are novel proteins in this context. Expression analysis of five important proteins, vimentin, gelsolin, alpha 2 HS glycoprotein (AHSG), glial fibrillary acidic protein (GFAP), and α1B-glycoprotein (A1BG) by Western blot analysis using their specific antibodies revealed their higher expression in RA synovial fluid as compared to non-RA samples. Recombinantly expressed GFAP and A1BG protein were used to develop an in-house ELISA to quantify the amount of autoantibodies in the RA patients. RA patients revealed an increase in the expression of GFAP and A1BG in the plasma as compared to osteoarthritis patients. Therefore, GFAP and A1BG can be proposed as potential new autoantigens of diagnostic importance for RA subjects. Further characterization of these proteins in rheumatoid arthritis will be helpful in understanding the role of these proteins in the disease pathogenesis providing new diagnostic tool with better specificity and accurate detection of the disease.

Altered glycosylation of plasma proteins has been directly implicated in the pathogenesis of rheumatoid arthritis (RA). The present study investigated the changes in the Concanavalin-A (Con-A)-bound plasma proteins in the RA patients in comparison to that of the healthy controls. Two proteins (MW approximately 32 kDa and approximately 62 kDa) showed an alteration in expression while an altered monosaccharide profile (high mannose) was observed in the approximately 62 kDa protein in the samples collected from RA patients. The 2-dimensional polyacrylamide gel electrophoresis analysis of the Con-A-bound plasma samples showed a large number of protein spots, a few of which were differentially expressed in the RA patients. Some unidentified proteins were detected in the RA patients which were absent in the control samples. The present study, therefore, enunciates the role of carbohydrates as well as that of the acute phase response in the disease pathogenesis.

The tumor suppressor Hippo pathway negatively regulates the transcriptional coactivators Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) to inhibit cell growth and control organ size, whereas activation of YAP and TAZ is implicated in tumorigenesis and cancer metastasis. Here, we report that the nonreceptor tyrosine kinase PYK2 positively regulates TAZ and YAP transcriptional activity in triple-negative breast cancer (TNBC). We found that inhibition of PYK2 expression or its kinase activity substantially affects the steady-state level of TAZ and markedly facilitates its proteasomal degradation. This effect was specific to PYK2 inhibition and was not obtained by inhibition of FAK. Destabilization of TAZ was associated with profound effect of PYK2 inhibition on cell growth at low-density concomitant with reduced expression of TAZ-target genes and induction of cell apoptosis. We further show that PYK2 enhances the tyrosine phosphorylation of both TAZ and LATS1/2 and concomitantly TAZ stability, and that PYK2 protein level correlates with the level of TAZ protein in primary breast tumors. Together these observations suggest that PYK2 is an important regulator of the Hippo pathway, and its tyrosine kinase activity has a striking effect on TAZ stabilization and activation in TNBC.