Biology subjects

Pulina, M.

Publications and source records attributed to Pulina, M..

3 recordsLinked to original sources

bioRxiv2024

The neuroendocrine transition in prostate cancer is dynamic and dependent on ASCL1

Lineage plasticity is a recognized hallmark of cancer progression that can shape therapy outcomes. The underlying cellular and molecular mechanisms mediating lineage plasticity remain poorly understood. Here, we describe a versatile in vivo platform to identify and interrogate the molecular determinants of neuroendocrine lineage transformation at different stages of prostate cancer progression. Adenocarcinomas reliably develop following orthotopic transplantation of primary mouse prostate organoids acutely engineered with human-relevant driver alterations (e.g., Rb1-/-; Trp53-/-; cMyc+ or Pten-/-; Trp53-/-; cMyc+), but only those with Rb1 deletion progress to ASCL1+ neuroendocrine prostate cancer (NEPC), a highly aggressive, androgen receptor signaling inhibitor (ARSI)-resistant tumor. Importantly, we show this lineage transition requires a native in vivo microenvironment not replicated by conventional organoid culture. By integrating multiplexed immunofluorescence, spatial transcriptomics and PrismSpot to identify cell type-specific spatial gene modules, we reveal that ASCL1+ cells arise from KRT8+ luminal epithelial cells that progressively acquire transcriptional heterogeneity, producing large ASCL1+;KRT8- NEPC clusters. Ascl1 loss in established NEPC results in transient tumor regression followed by recurrence; however, Ascl1 deletion prior to transplantation completely abrogates lineage plasticity, yielding adenocarcinomas with elevated AR expression and marked sensitivity to castration. The dynamic feature of this model reveals the importance of timing of therapies focused on lineage plasticity and offers a platform for identification of additional lineage plasticity drivers.

cell biology↗

bioRxiv2023

Rational development of a small-molecule activator of CK1γ2 that decreases C99 and beta-amyloid levels

Alzheimers disease (AD) is a debilitating neurodegenerative disorder characterized by the accumulation of beta-amyloid (A{beta}), C99, and Tau in vulnerable areas of the brain. Despite extensive research, current strategies to lower A{beta} levels have shown limited efficacy in slowing the cognitive decline associated with AD. Recent findings suggest that C99 may also play a crucial role in the pathogenesis of AD. Our laboratory has discovered that CK1{gamma}2 phosphorylates Presenilin 1 at the {gamma}-secretase complex, leading to decreased C99 and A{beta} levels. Thus, CK1{gamma}2 activation appears as a promising therapeutic target to lower both C99 and A{beta} levels. In this study, we demonstrate that CK1{gamma}2 is inhibited by intramolecular autophosphorylation and describe a high-throughput screen designed to identify inhibitors of CK1{gamma}2 autophosphorylation. We hypothesize that these inhibitors could lead to CK1{gamma}2 activation and increased PS1-Ser367 phosphorylation, ultimately reducing C99 and A{beta} levels. Using cultured cells, we investigated the impact of these compounds on C99 and A{beta} concentrations and confirmed that CK1{gamma}2 activation effectively reduces their levels. Our results provide proof of concept that CK1{gamma}2 is an attractive therapeutic target for AD. Future studies should focus on the identification of specific compounds that can inhibit CK1{gamma}2 autophosphorylation and evaluate their efficacy in preclinical models of AD. These studies will pave the way for the development of novel therapeutics for the treatment of AD.

pharmacology and toxicology↗

bioRxiv2019

C99, not beta-amyloid, is associated with selective death of vulnerable neurons in Alzheimer's disease.

IntroductionThe levels and distribution of amyloid deposits in the brain does not correlate well with Alzheimers disease (AD) progression. Therefore, it is likely that Amyloid-precursor-protein proteolytic fragments other than beta-amyloid contribute to the onset of AD.\n\nMethodsWe developed a sensitive assay adapted to the detection of C99, the direct precursor of beta-amyloid. Three postmortem groups were studied: control with normal and stable cognition; subjects with moderate AD, and individuals with severe AD. The amount of C99 and beta-amyloid was quantified and correlated with the severity of AD.\n\nResultsC99 accumulates in vulnerable neurons, and its levels correlate with the degree of cognitive impairment in patients suffering from AD. In contrast, beta-amyloid levels are increased in both vulnerable and resistant brain areas.\n\nDiscussionThese results raise the possibility that C99, rather than beta-amyloid plaques, is responsible for the death of nerve cells in Alzheimers disease.

neuroscience↗