Biology subjects

Wahi, K.

Publications and source records attributed to Wahi, K..

3 recordsLinked to original sources

bioRxiv2024

Macropinocytosis mediates resistance to loss of glutamine transport in triple-negative breast cancer

Triple-negative breast cancer (TNBC) relies on glutamine uptake by the transporter ASCT2 to sustain their unique glutamine metabolism and growth. Despite previous data showing cell growth inhibition after ASCT2 knockdown, ASCT2 CRISPR knockout was well-tolerated by breast cancer cell lines. Despite the loss of a glutamine transporter and low rate of glutamine uptake, intracellular glutamine steady state levels were higher in ASCT2 knockout compared to control TNBC cells. Proteomics data revealed upregulation of macropinocytosis, reduction in glutamine efflux and glutamine synthesis in ASCT2 knockout cells. Loss of ASCT2 in TNBC cell line HCC1806 induced a 5-10-fold increase in macropinocytosis across 5 separate ASCT2 knockout clones, compared to a modest 2-fold increase in the shRNA ASCT2 knockdown. By comparison, ASCT2 knockout impaired cell proliferation in a non-macropinocytic breast cancer cell line, HCC1569. These data suggest that macropinocytosis provides a novel resistance mechanism to strategies targeting glutamine uptake alone. Despite this adaptation, TNBC cells continue to rely on glutamine metabolism for their growth, which suggests therapeutic targeting may need to focus on downstream glutamine metabolism pathways.

cancer biology↗

bioRxiv2024

Integration of hyperspectral imaging and transcriptomics from individual cells with HyperSeq

Microscopy and omics are complementary approaches to probe the molecular state of cells in health and disease, combining granularity with scalability. While important advances have been achieved over the last decade in each area, integrating both imaging- and sequencing-based assays on the same cell has proven challenging. In this study, a new approach called HyperSeq that combines hyperspectral autofluorescence imaging with transcriptomics on the same cell is demonstrated. HyperSeq was applied to Michigan Cancer Foundation 7 (MCF-7) breast cancer cells and identified a subpopulation of cells exhibiting bright autofluorescence rings at the plasma membrane in optical channel 13 ({lambda}ex = 431 nm,{lambda} em = 594 nm). Correlating the presence of a ring with the gene expression in the same cell indicated that ringed cells are more likely to express hallmark genes of apoptosis and less likely to express genes associated with ATP production. Further, correlation of cell morphology with gene expression suggested that multiple members of the spliceosome were downregulated in larger MCF-7 cells. Multiple genes were evenly expressed across cell sizes but also exhibited higher usage of specific exons in larger or smaller cells. Finally, correlation between gene expression and fluorescence within the spectral range of Nicotinamide adenine dinucleotide hydrogen (NADH) provided insight into the metabolic states of MCF-7 cells. These observations provided a link between the cells optical spectrum and its internal molecular state, demonstrating the utility of HyperSeq to study cell biology at single cell resolution by integrating spectral, morphological and transcriptomic analyses into a single, streamlined workflow.

bioinformatics↗

bioRxiv2020

Inhibition of guanosine monophosphate synthetase (GMPS) blocks glutamine metabolism and prostate cancer growth in vitro and in vivo

Cancer cells increase their uptake of nutrients and metabolize them to provide the necessary building blocks for new cancer cells. Glutamine is a critical nutrient in cancer, however its contribution to purine metabolism in prostate cancer has not previously been determined. Guanosine monophosphate synthetase (GMPS) acts in the de novo purine biosynthesis pathway, utilizing a glutamine amide to synthesize the guanine nucleotide and replenish the purine pool in proliferative cancer cells. This study demonstrates that GMPS mRNA expression correlates with Gleason score in prostate cancer samples, while high GMPS expression was associated with decreased rates of overall and disease/progression-free survival. Pharmacological inhibition or knockdown of GMPS significantly decreased cell growth in both LNCaP and PC-3 prostate cancer cells. GMPS knockdown was rescued by addition of extracellular guanosine to the media, suggesting a direct effect on nucleotide synthesis. We utilized 15N-(amide)-glutamine and U-13C5-glutamine metabolomics to dissect the pathways involved, and intriguingly, despite similar growth inhibition by GMPS knockdown, we show unique metabolic effects across each cell line. PC-3 cells showed a build-up of purine precursors, as well as activation of purine salvage pathways highlighted by significant increases in guanine, adenosine, inosine and cytosine. Both cell lines exhibited increased levels of pyrimidines and prioritized TCA cycle in distinct ways to produce increased aspartate, another important purine precursor. Using a PC-3 xenograft mouse model, tumor growth was also significantly decreased after GMPS knockdown. These data further highlight the importance of glutamine metabolism for prostate cancer cell growth and provide support for GMPS as a new therapeutic target in prostate cancer.

cancer biology↗