Biology subjects

SENGUPTA, S.

Publications and source records attributed to SENGUPTA, S..

3 recordsLinked to original sources

bioRxiv2024

Dysregulated Cholesterol Metabolism with Anomalous PI3K/Akt/mTOR pathway Predicts Poor Carboplatin Response in High Grade Serous Ovarian Cancer

Rapidly escalating High-Grade Serous Ovarian Cancer (HGSOC) incidences, relapse, and mortalities result from failed carboplatin therapy. In this regard, reprogrammed cholesterol metabolism arising from deregulated PI3K/Akt/mTOR signaling aggravates HGSOCs to evade carboplatin. Therefore, we designed a pilot study to ascertain their clinical relevance in determining the carboplatin response of HGSOC tumors. Non-NACT HGSOC (n=31) subjects were classified into optimum, borderline, and high cohorts based on blood cholesterol levels which positively correlated with their relative tissue cholesterol content. TCGA database showed that mutations in specific PI3K/Akt/mTOR candidates including cholesterol metabolism regulators (SREBP1, SREBP2, SRB-1, STAR, HMGCR) and prosurvival effectors (Akt, mTOR, p70S6K, P38MAPK, HIF-1, COX2, VEGF) are characteristic to HGSOCs. We discerned dysregulations (expressions/activity) in SREBP2, SRB-1, STAR, and HMGCR along with Akt/pAktThr308, mTOR/pmTORSer2448, p70S6K, P38MAPK, HIF-1, COX2, and VEGF proteins within high cohort. Herein, poorly differentiated tumors with escalated HMGCR activity overproduced cholesterol thereby rigidifying their cell membranes to restrain Pt-DNA adduct retention. With a carboplatin IC50 of 5.23{micro}M, high cohort tumors generated lesser drug-induced ROS and espoused unaltered mitochondrial-membrane depolarization and DNA damage profiles. These parameters were moderately altered in the borderline-HGSOC cohort possessing relatively less rigid membranes and a lower carboplatin IC50 of 2.78{micro}M. Accordingly, borderline and high cohorts were respectively denoted as intermediate responder and non-responder of carboplatin. On the contrary, the cholesterol-deficient optimum cohort (IC50-1.59{micro}M) with fluid membranes was a carboplatin responder group. Our study established the candidature of abnormal cholesterol and PI3K/Akt/mTOR (protein-level) statuses as predictive markers to screen HGSOCs for carboplatin responses before therapy.

cancer biology↗

bioRxiv2023

TGF-β1 activates neutrophil signaling and gene expression but not migration

Tumor-associated neutrophils are found in many types of cancer and are often reported to contribute to negative outcomes. The presence of transforming growth factor-beta (TGF-{beta}) in the tumor microenvironment reportedly contributes to the skewing of neutrophils to a more pro-tumor phenotype. The effects of TGF-{beta} on neutrophil signaling and migration are, however, unclear. We sought to characterize TGF-{beta} signaling in both primary human neutrophils and the neutrophil-like cell line HL-60 and determine whether it directly induces neutrophil migration. We found that TGF-{beta}1 does not induce neutrophil chemotaxis in transwell or underagarose migration assays. TGF-{beta}1 does activate canonical signaling through SMAD3 and noncanonical signaling through ERK1/2 in neutrophils in a time-and dose-dependent manner. Additionally, TGF-{beta}1 present in the tumor-conditioned media (TCM) of invasive breast cancer cells results in SMAD3 activation. We discovered that TCM induces neutrophils to secrete leukotriene B4 (LTB4), which is a lipid mediator important for amplifying the range of neutrophil recruitment. However, TGF-{beta}1 alone does not induce secretion of LTB4. RNA-sequencing revealed that TGF-{beta}1 and TCM alter gene expression in HL-60 cells, including the mRNA levels of the pro-tumor oncostatin M (OSM) and vascular endothelial growth factor A (VEGFA). These new insights into the role and impact of TGF-{beta}1 on neutrophil signaling, migration, and gene expression have significant implications in the understanding of the changes in neutrophils that occur in the tumor microenvironment.

immunology↗

bioRxiv2021

TRIPLE-NEGATIVE BREAST CANCER CELLS RECRUIT NEUTROPHILS BY SECRETING TGF-β AND CXCR2 LIGANDS

Tumor associated neutrophils (TANs) are frequently detected in triple-negative breast cancer (TNBC). Recent studies also reveal the importance of neutrophils in promoting tumor progression and metastasis during breast cancer. However, the mechanisms regulating neutrophil trafficking to breast tumors are less clear. We sought to determine whether neutrophil trafficking to breast tumors is determined directly by the malignant potential of cancer cells. We found that tumor conditioned media (TCM) harvested from highly aggressive, metastatic TNBC cells induced a polarized morphology and robust neutrophil migration, while TCM derived from poorly aggressive estrogen receptor positive (ER+) breast cancer cells had no activity. In a three-dimensional (3D) type-I collagen matrix, neutrophils migrated toward TCM from aggressive breast cancer cells with increased velocity and directionality. Moreover, in a neutrophil-tumor spheroid co-culture system, neutrophils migrated with increased directionality towards spheroids generated from TNBC cells compared to ER+ cells. Based on these findings, we next sought to characterize the active factors secreted by TNBC cell lines. We found that TCM-induced neutrophil migration is dependent on tumor-derived chemokines, and screening TCM elution fractions based on their ability to induce polarized neutrophil morphology revealed the molecular weight of the active factors to be around 12 kDa. TCM from TNBC cell lines contained copious amounts of GRO (CXCL1/2/3) chemokines and TGF-{beta} cytokines compared to ER+ cell-derived TCM. TCM activity was inhibited by simultaneously blocking receptors specific to GRO chemokines and TGF-{beta}, while the activity remained intact in the presence of either single receptor inhibitor. Together, our findings establish a direct link between the malignant potential of breast cancer cells and their ability to induce neutrophil migration. Our study also uncovers a novel coordinated function of TGF-{beta} and GRO chemokines responsible for guiding neutrophil trafficking to the breast tumor.

immunology↗