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Saumendra Bajpai

Bio: Saumendra Bajpai is an academic researcher from Indian Institute of Technology Madras. The author has contributed to research in topics: Cell adhesion & Cancer cell. The author has an hindex of 11, co-authored 24 publications receiving 1355 citations. Previous affiliations of Saumendra Bajpai include Johns Hopkins University School of Medicine & Indian Institute of Technology Bombay.

Papers
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Journal ArticleDOI
TL;DR: It is demonstrated that hypoxia-inducible factor 1 (HIF-1) is a critical regulator of ECM remodeling by fibroblasts under hypoxic conditions, which induces changes in breast cancer cell morphology, adhesion, and motility that promote invasion and metastasis.

402 citations

Journal ArticleDOI
TL;DR: In a diet-induced model of obesity, arterial stiffness, measured in vivo, develops within 1 month of the initiation of the diet and precedes the development of hypertension by 5 months, supporting the hypothesis that arterial stiffening is a cause rather than a consequence of hypertension.
Abstract: Stiffening of conduit arteries is a risk factor for cardiovascular morbidity. Aortic wall stiffening increases pulsatile hemodynamic forces that are detrimental to the microcirculation in highly perfused organs, such as the heart, brain, and kidney. Arterial stiffness is associated with hypertension but presumed to be due to an adaptive response to increased hemodynamic load. In contrast, a recent clinical study found that stiffness precedes and may contribute to the development of hypertension although the mechanisms underlying hypertension are unknown. Here, we report that in a diet-induced model of obesity, arterial stiffness, measured in vivo, develops within 1 month of the initiation of the diet and precedes the development of hypertension by 5 months. Diet-induced obese mice recapitulate the metabolic syndrome and are characterized by inflammation in visceral fat and aorta. Normalization of the metabolic state by weight loss resulted in return of arterial stiffness and blood pressure to normal. Our findings support the hypothesis that arterial stiffness is a cause rather than a consequence of hypertension.

283 citations

Journal ArticleDOI
TL;DR: It is demonstrated that hypoxia-inducible factor 1 activates the transcription of genes encoding collagen prolyl hydroxylases that are critical for collagen deposition by breast cancer cells, resulting in enhanced invasion and metastasis to lymph nodes and lungs.
Abstract: The presence of hypoxia and fibrosis within the primary tumor are two major risk factors for metastasis of human breast cancer. In this study, we demonstrate that hypoxia-inducible factor 1 activates the transcription of genes encoding collagen prolyl hydroxylases that are critical for collagen deposition by breast cancer cells. We show that expression of collagen prolyl hydroxylases promotes cancer cell alignment along collagen fibers, resulting in enhanced invasion and metastasis to lymph nodes and lungs. Finally, we establish the prognostic significance of collagen prolyl hydroxylase mRNA expression in human breast cancer biopsies and show that ethyl 3,4-dihydroxybenzoate, a prolyl hydroxylase inhibitor, decreases tumor fibrosis and metastasis in a mouse model of breast cancer.

256 citations

Journal ArticleDOI
TL;DR: It is shown that PLOD2 is critical for fibrillar collagen formation by breast cancer cells, increases tumor stiffness, and is required for metastasis to lymph nodes and lungs.
Abstract: Metastasis is the leading cause of death among patients who have breast cancer. Understanding the role of the extracellular matrix in the metastatic process may lead to the development of improved therapies to treat cancer patients. Intratumoral hypoxia, found in the majority of breast cancers, is associated with an increased risk of metastasis and mortality. We found that in hypoxic breast cancer cells, HIF-1 activates transcription of the PLOD1 and PLOD2 genes encoding procollagen lysyl hydroxylases that are required for the biogenesis of collagen, which is a major constituent of the extracellular matrix. High PLOD2 expression in breast cancer biopsies is associated with increased risk of mortality. We demonstrate that PLOD2 is critical for fibrillar collagen formation by breast cancer cells, increases tumor stiffness, and is required for metastasis to lymph nodes and lungs.

215 citations

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TL;DR: A simple mechanical model explains why LINC complexes and the perinuclear actin cap are essential in 3D migration by providing mechanical support to the formation of pseudopodial protrusions.
Abstract: Cells often migrate in vivo in an extracellular matrix that is intrinsically three-dimensional (3D) and the role of actin filament architecture in 3D cell migration is less well understood. Here we show that, while recently identified linkers of nucleoskeleton to cytoskeleton (LINC) complexes play a minimal role in conventional 2D migration, they play a critical role in regulating the organization of a subset of actin filament bundles – the perinuclear actin cap - connected to the nucleus through Nesprin2giant and Nesprin3 in cells in 3D collagen I matrix. Actin cap fibers prolong the nucleus and mediate the formation of pseudopodial protrusions, which drive matrix traction and 3D cell migration. Disruption of LINC complexes disorganizes the actin cap, which impairs 3D cell migration. A simple mechanical model explains why LINC complexes and the perinuclear actin cap are essential in 3D migration by providing mechanical support to the formation of pseudopodial protrusions.

142 citations


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Journal ArticleDOI
21 Jan 2016-Nature
TL;DR: An improved understanding of the mechanistic determinants of such colonization is needed to better prevent and treat metastatic cancer.
Abstract: Metastasis is the main cause of death in people with cancer. To colonize distant organs, circulating tumour cells must overcome many obstacles through mechanisms that we are only now starting to understand. These include infiltrating distant tissue, evading immune defences, adapting to supportive niches, surviving as latent tumour-initiating seeds and eventually breaking out to replace the host tissue. They make metastasis a highly inefficient process. However, once metastases have been established, current treatments frequently fail to provide durable responses. An improved understanding of the mechanistic determinants of such colonization is needed to better prevent and treat metastatic cancer.

1,342 citations

Journal ArticleDOI
15 Apr 2010-Nature
TL;DR: The differential mutation frequencies and structural variation patterns in metastasis and xenograft compared with the primary tumour indicate that secondary tumours may arise from a minority of cells within thePrimary tumour.
Abstract: Massively parallel DNA sequencing technologies provide an unprecedented ability to screen entire genomes for genetic changes associated with tumour progression. Here we describe the genomic analyses of four DNA samples from an African-American patient with basal-like breast cancer: peripheral blood, the primary tumour, a brain metastasis and a xenograft derived from the primary tumour. The metastasis contained two de novo mutations and a large deletion not present in the primary tumour, and was significantly enriched for 20 shared mutations. The xenograft retained all primary tumour mutations and displayed a mutation enrichment pattern that resembled the metastasis. Two overlapping large deletions, encompassing CTNNA1, were present in all three tumour samples. The differential mutation frequencies and structural variation patterns in metastasis and xenograft compared with the primary tumour indicate that secondary tumours may arise from a minority of cells within the primary tumour.

1,147 citations

Journal ArticleDOI
TL;DR: The metastatic process is reconstructed and the importance of key physical and mechanical processes at each step of the cascade is described, which may help to solve some long-standing questions in disease progression and lead to new approaches to developing cancer diagnostics and therapies.
Abstract: Metastasis is a complex, multistep process responsible for >90% of cancer-related deaths. In addition to genetic and external environmental factors, the physical interactions of cancer cells with their microenvironment, as well as their modulation by mechanical forces, are key determinants of the metastatic process. We reconstruct the metastatic process and describe the importance of key physical and mechanical processes at each step of the cascade. The emerging insight into these physical interactions may help to solve some long-standing questions in disease progression and may lead to new approaches to developing cancer diagnostics and therapies.

1,073 citations

Journal ArticleDOI
TL;DR: A direct link between hypoxia and the composition and the organization of the ECM is established, which suggests a new model in which multiple microenvironmental signals might converge to synergistically influence metastatic outcome.
Abstract: Of the deaths attributed to cancer, 90% are due to metastasis, and treatments that prevent or cure metastasis remain elusive. Emerging data indicate that hypoxia and the extracellular matrix (ECM) might have crucial roles in metastasis. During tumour evolution, changes in the composition and the overall content of the ECM reflect both its biophysical and biological properties and these strongly influence tumour and stromal cell properties, such as proliferation and motility. Originally thought of as independent contributors to metastatic spread, recent studies have established a direct link between hypoxia and the composition and the organization of the ECM, which suggests a new model in which multiple microenvironmental signals might converge to synergistically influence metastatic outcome.

1,034 citations

Journal ArticleDOI
TL;DR: Hypoxia-inducible factors play a protective role in the pathophysiology of myocardial ischemia due to coronary artery disease, limb ischemies due to peripheral arterial disease, pressure-overload heart failure, wound healing, and chronic rejection of organ transplants.
Abstract: Hypoxia-inducible factors (HIFs) are transcriptional activators that function as master regulators of oxygen homeostasis, which is disrupted in disorders affecting the circulatory system and in cancer. The role of HIFs in these diseases has been elucidated by clinical studies and by analyses of mouse models. HIFs play a protective role in the pathophysiology of myocardial ischemia due to coronary artery disease, limb ischemia due to peripheral arterial disease, pressure-overload heart failure, wound healing, and chronic rejection of organ transplants. In contrast, HIFs contribute to the pathogenesis of pulmonary arterial hypertension, systemic hypertension associated with sleep apnea, ocular neovascularization, hereditary erythrocytosis, and cancer.

883 citations