Biology subjects

Moshiri, A. S.

Publications and source records attributed to Moshiri, A. S..

3 recordsLinked to original sources

bioRxiv2026

Melanoma evolution in the lymph node shapes systemic outcomes

Lymph node (LN) metastasis predicts poor patient outcomes, but the mechanistic drivers that shape metastatic fitness, immune evasion, and clinical impact remain elusive. While preclinical models indicate that active tumor adaptation is necessary for LN metastasis, observations of clonal heterogeneity in human tumors has supported a stochastic model of passive and continuous seeding. Reconciling LN metastasis as a passive or active process is essential to understanding if LN metastasis is simply a marker of disease progression or a clinically informative therapeutic target. Here, we report evidence that LNs are active niches that facilitate ongoing melanoma evolution to progressively subvert immune surveillance and enable progression. To construct a spatial trajectory of LN metastasis, we examined paired primary melanomas and metastatic sentinel LNs through integrated genomic, phenotypic, and immunologic analyses. In contrast to a model of continuous seeding, we observe that early dissemination from the primary tumor is followed by extensive intra-nodal diversification, indicating that metastatic outgrowth requires ongoing adaptation within the LN. As clones evolve in the LN, they re-differentiate towards a melanocytic state and reprogram the microenvironment for immune exclusion. In further evolved clones, loss of inflammatory interferon signaling and induction of p53 and mitochondrial stress are associated with decreased overall survival. Collectively, these results implicate the LN as a critical battleground for melanoma progression, where tumor evolution drives adaptation and immune escape to biologically link regional metastasis to patient survival.

cancer biology↗

bioRxiv2026

Chromatin architecture and physical constriction cooperate in phenotype switching and cancer cell dissemination

Phenotypic plasticity is a prominent cancer feature that contributes to metastatic potential and resistance to therapy across multiple cancer types. Cancer cell state transitions have been attributed to transcriptional programs, such as the AP1/TEAD-regulated gene network driving the mesenchymal-like (MES) phenotype. In addition, during dissemination, tumor cells are subjected to variable loads of physical mechanical pressure and constriction across transited tissue, which are thought to impact nuclear molecular crowding. How the interplay between mechanical pressure, global 3D nuclear architecture and transcriptional programs contributes to MES identity and metastatic adaptation remains unclear. Using cutaneous melanoma as a model for early dissemination, we integrate in vitro and in vivo epigenomic profiling with nanoscale imaging of cell lines and patient samples to investigate chromatin organization features underlying the MES phenotype. We find that in MES cells, CTCF is relocated from domain boundaries to regulatory regions of EMT-like genes, leading to reduced insulation, extended topological associated domains (TADs) and increased inter-domain contacts, and de novo formation of chromatin hubs. This conformational rewiring, along with loss of heterochromatin, supports nuclear deformability during invasion and dissemination. Conversely, physical constriction of melanocytic cells induces MES-like chromatin features--including CTCF repositioning and heterochromatin loss-- and promotes metastasis in vivo. Similarly, pharmacological inhibition of the heterochromatin mark H3K9me3 triggers MES characteristics and increases invasiveness. These results demonstrate that metastatic competency involves both epigenetic and structural nuclear reprogramming, enabling shifts in gene networks and physical adaptability. Our findings reveal mechanistic links between nuclear architecture and aggressive tumor behavior, identifying potential biomarkers and therapeutic targets to intercept metastatic progression.

cancer biology↗

bioRxiv2025

B cells specific for polyomavirus-derived oncoprotein are predictive of Merkel cell carcinoma progression

Merkel cell carcinomas typically arise from clonal integration of the Merkel cell polyomavirus. Immunogenic viral oncoproteins then lead to tumorigenesis. Oncoprotein-specific T cells are essential for anti-MCC immunity, but it is unclear whether B cells promote tumor control. Here, we analyzed the frequency and phenotype of viral oncoprotein-specific and total B cells in 47 blood samples and 19 unmatched tumors from MCC patients-- of which 8 out 19 progressed. The phenotype of blood B cells did not correlate with MCC patient outcomes. In contrast, all 11 patients with robust oncoprotein-specific antibody-secreting and/or germinal center B cells in tumors experienced long-term MCC control. In vitro, B cells engineered to be specific for viral oncoproteins increased the sensitivity of oncoprotein-specific CD4+ T cells by over 50-fold. Together, our findings suggest that cancer-specific B cells promote anti-tumor immunity via increased T cell responses and that cancer-specific B cell augmentation could be therapeutically relevant. Statement of SignificanceThe link between cancer-specific B cells in anti-tumor immunity and clinical outcomes remains poorly defined. Here, we show that tumor-associated B cells specific for a viral oncoprotein expressed in MCC patient tumors predict disease control with remarkable accuracy, establishing their potential as active participants in tumor immunity.

immunology↗