Biomedical subjects

Melody Stallings-Mann

Publications and source records attributed to Melody Stallings-Mann.

4 recordsLinked to original sources

PubMed2026

Menopausal timing and senescent-immune coupling in age-related lobular involution of the human breast: a longitudinal cohort study.

BACKGROUND: Incomplete postmenopausal breast involution leaves persistent epithelial-rich lobules and elevated breast density in about 40% of women and is associated with higher breast cancer risk, but why remodelling stalls remains unclear. METHODS: We studied a longitudinal cohort of 81 women with paired benign breast biopsies (baseline age 45-55 years; follow-up 2-10 years), all with baseline NanoString transcriptomics and two-timepoint digital morphometry, and with multiplex immunofluorescence in spatial-imaging subsets (baseline n = 14-16 depending on panel; follow-up n = 14). A separate postmenopausal endpoint cohort (12 women: eight noninvoluted, four completely involuted), profiled by genome-wide expression array and multiplex immunofluorescence, defined the persistent-lobule phenotype. FINDINGS: Noninvoluted postmenopausal tissue retained a proliferation-competent, tumour-associated epithelial state and showed immune accumulation at lobular boundaries with reduced access to p16+ (senescence-associated) epithelial foci. The same SASP and innate immune programmes that predicted slower involution across the menopausal transition predicted faster involution after menopause. Follow-up boundary CD45→p16 engagement was directionally consistent with this reversal in Pre→Post and Post→Post women. Spatial imaging resolved this reversal into a perimenopausal stall architecture and a postmenopausal clearance-associated architecture marked by direct CD16+ innate-effector engagement of p16+ epithelium; macrophage targeting provided convergent support (two-sided exact permutation interaction p = 0.0077). INTERPRETATION: Menopausal timing conditions whether senescent-immune programmes couple to productive clearance or to spatially uncoupled surveillance and persistent risk-associated tissue. Biomarker interpretation should therefore be anchored to menopausal timing. FUNDING: Casey DeSantis Cancer Fund and US National Cancer Institute.

Humans↗

PubMed2006

Aurothiomalate inhibits transformed growth by targeting the PB1 domain of protein kinase Ciota.

We recently identified the gold compound aurothiomalate (ATM) as a potent inhibitor of the Phox and Bem1p (PB1)-PB1 domain interaction between protein kinase C (PKC) iota and the adaptor molecule Par6. ATM also blocks oncogenic PKCiota signaling and the transformed growth of human lung cancer cells. Here we demonstrate that ATM is a highly selective inhibitor of PB1-PB1 domain interactions between PKCiota and the two adaptors Par6 and p62. ATM has no appreciable inhibitory effect on other PB1-PB1 domain interactions, including p62-p62, p62-NBR1, and MEKK3-MEK5 interactions. ATM can form thio-gold adducts with cysteine residues on target proteins. Interestingly, PKCiota (and PKCzeta) contains a unique cysteine residue, Cys-69, within its PB1 domain that is not present in other PB1 domain containing proteins. Cys-69 resides within the OPR, PC, and AID motif of PKCiota at the binding interface between PKCiota and Par6 where it interacts with Arg-28 on Par6. Molecular modeling predicts formation of a cysteinyl-aurothiomalate adduct at Cys-69 that protrudes into the binding cleft normally occupied by Par6, providing a plausible structural explanation for ATM inhibition. Mutation of Cys-69 of PKCiota to isoleucine or valine, residues frequently found at this position in other PB1 domains, has little or no effect on the affinity of PKCiota for Par6 but confers resistance to ATM-mediated inhibition of Par6 binding. Expression of the PKCiota C69I mutant in human non-small cell lung cancer cells confers resistance to the inhibitory effects of ATM on transformed growth. We conclude that ATM inhibits cellular transformation by selectively targeting Cys-69 within the PB1 domain of PKCiota.

Adaptor Proteins, Signal Transducing↗

PubMed2006

A novel small-molecule inhibitor of protein kinase Ciota blocks transformed growth of non-small-cell lung cancer cells.

We recently showed that atypical protein kinase Ciota (PKCiota) is required for transformed growth of human non-small-cell lung cancer (NSCLC) cells by activating Rac1. Genetic disruption of PKCiota signaling blocks Rac1 activity and transformed growth, indicating that PKCiota is a viable target for development of novel therapeutics for NSCLC. Here, we designed and implemented a novel fluorescence resonance energy transfer-based assay to identify inhibitors of oncogenic PKCiota signaling. This assay was used to identify compounds that disrupt the interaction between PKCiota and its downstream effector Par6, which links PKCiota to Rac1. We identified aurothioglucose (ATG), a gold compound used clinically to treat rheumatoid arthritis, and the related compound, aurothiomalate (ATM), as potent inhibitors of PKCiota-Par6 interactions in vitro (IC(50) approximately 1 micromol/L). ATG blocks PKCiota-dependent signaling to Rac1 and inhibits transformed growth of NSCLC cells. ATG-mediated inhibition of transformation is relieved by expression of constitutively active Rac1, consistent with a mechanism at the level of the interaction between PKCiota and Par6. ATG inhibits A549 cell tumor growth in nude mice, showing efficacy against NSCLC in a relevant preclinical model. Our data show the utility of targeting protein-protein interactions involving PKCiota for antitumor drug development and provide proof of concept that chemical disruption of PKCiota signaling can be an effective treatment for NSCLC. ATG and ATM will be useful reagents for studying PKCiota function in transformation and represent promising new agents for the clinical treatment of NSCLC.

Adaptor Proteins, Signal Transducing↗

PubMed2003

Spontaneous activation and signaling by overexpressed epidermal growth factor receptors in glioblastoma cells.

Overexpressed epidermal growth receptor factor receptors (EGFRs) are thought to contribute to the malignant phenotype of human glioblastomas (GBMs), but the mechanism is not well understood. We found that SKMG-3 cells, a rare GBM cell line that maintains EGFR gene amplification in vitro, produced high levels of EGFR protein. The cells also expressed the related receptors HER2/neu and HER4, but not HER3. Immunoblots and tryptic phosphopeptide maps showed that the SKMG-3 EGFRs were intact and functional and that a subset of these receptors were spontaneously autophosphorylated. EGF treatment stimulated phosphorylation of the EGFRs as well as the downstream effectors Erk, AKT1, stat3 and c-Cbl. Under minimal growth conditions, the unstimulated SKMG-3 cells contained constitutively phosphorylated Erk and AKTI but no detectable stat3 DNA-binding complexes. The EGFR kinase inhibitor PD158780 reduced the constitutive phosphorylation of the receptor and Erk but not that of AKT1. In contrast, inhibition of phosphatidylinositol-3-kinase (PI3K) blocked the constitutive phosphorylation of Erk and AKT-1 but not the EGFR. We conclude that the SKMG-3 cells represent the subset of GBMs with amplified EGFR genes that overexpress intact receptors. The results also suggest that in some GBMs, signals from overexpressed EGFRs contribute to the constitutive phosphorylation of Erk, but these signals may not required for the constitutive activation of PI3K or AKT1.

Breast Neoplasms↗