Hyperglycemia Associated Metabolic and Molecular Alterations in Cancer Risk, Progression, Treatment, and Mortality.

Cancer and diabetes are amongst the leading causes of deaths worldwide. There is an alarming rise in cancer incidences and mortality, with approximately 18.1 million new cases and 9.6 million deaths in 2018. A major contributory but neglected factor for risk of neoplastic transformation is hyperglycemia. Epidemiologically too, lifestyle patterns resulting in high blood glucose level, with or without the role of insulin, are more often correlated with cancer risk, progression, and mortality. The two conditions recurrently exist in comorbidity, and their interplay has rendered treatment regimens more challenging by restricting the choice of drugs, affecting surgical consequences, and having associated fatal complications. Limited comprehensive literature is available on their correlation, and a lack of clarity in understanding in such comorbid conditions contributes to higher mortality rates. Hence, a critical analysis of the elements responsible for enhanced mortality due to hyperglycemia-cancer concomitance is warranted. Given the lifestyle changes in the human population, increasing metabolic disorders, and glucose addiction of cancer cells, hyperglycemia related complications in cancer underline the necessity for further in-depth investigations. This review, therefore, attempts to shed light upon hyperglycemia associated factors in the risk, progression, mortality, and treatment of cancer to highlight important mechanisms and potential therapeutic targets.

Noncoding RNA Ginir functions as an oncogene by associating with centrosomal proteins.

Long noncoding RNAs constitute a major fraction of the eukaryotic transcriptome, and together with proteins, they intricately fine-tune various growth regulatory signals to control cellular homeostasis. Here, we describe the functional characterisation of a novel pair of long intergenic noncoding RNAs (lincRNAs) comprised of complementary, fully overlapping sense and antisense transcripts Genomic Instability Inducing RNA (Ginir) and antisense RNA of Ginir (Giniras), respectively, from mouse cells. This transcript pair is expressed in a spatiotemporal manner during embryonic development. The individual levels of the sense and antisense transcripts are finely balanced during embryonic growth and in adult tissues. Functional studies of the individual transcripts performed using overexpression and knock-down strategies in mouse cells has led to the discovery that Ginir RNA is a regulator of cellular proliferation and can act as an oncogene having a preeminent role in malignant transformation. Mechanistically, we demonstrate that the oncogenic function of Ginir is mediated by its interaction with centrosomal protein 112 (Cep112). Additionally, we establish here a specific interaction between Cep112 with breast cancer type 1 susceptibility protein (Brca1), another centrosome-associated protein. Next, we prove that the mutual interaction between Cep112 with Brca1 is significant for mitotic regulation and maintenance of genomic stability. Furthermore, we demonstrate that the Cep112 protein interaction with Brca1 protein is impaired when an elevated level of Ginir RNA is present in the cells, resulting in severe deregulation and abnormality in mitosis, leading to malignant transformation. Inhibiting the Ginir RNA function in transformed cells attenuates transformation and restores genomic stability. Together, these findings unravel, to our knowledge, a hitherto-unknown mechanism of oncogenesis mediated by a long noncoding RNA and establishes a unique role of Cep112-Brca1 interaction being modulated by Ginir RNA in maintaining mitotic fidelity.

Dlxin-1, a MAGE family protein, induces accelerated neurite outgrowth and cell survival by enhanced and early activation of MEK and Akt signalling pathways in PC12 cells.

Dlxin-1 (also known as NRAGE or MAGED1) is a member of Type II melanoma-associated antigen (MAGE) family of proteins characterized by presence of a unique region of about 200 amino acids known as the MAGE homology domain (MHD). Dlxin-1 is associated with a large number of diverse cellular functions ranging from transcriptional regulation, cell cycle progression and differentiation to developmental apoptosis. While there are numerous studies reporting the role of NRAGE in facilitating cell death by interaction with p75NTR, we found varied effects of Dlxin-1 over-expression on PC12 cells grown in presence of NGF. These include induction of increased cell survival in presence of NGF and accelerated neuronal differentiation. We here categorically demonstrate that the effects on neuritogenesis are promoted through interactions of Dlxin-1 with the neurotrophin receptor TrkA. Further, using pharmacological inhibitors to specific pathways, we delineate the effects on enhanced neuritogenesis to the early and sustained activation of MEK pathway whereas the effects on cell survival to the early activation of Akt pathway. Next, we demonstrate a physical interaction of necdin with Dlxin-1 in PC12 cells. Our results establish that Dlxin-1 is an enhancer of neuronal differentiation and suggests that its possible interaction with NGF and necdin is critical in mediating pathways involved in neuronal survival and differentiation. Further in-depth analyses of the activation of various signalling pathways mediated through interaction with Dlxin-1 may provide valuable insight on the mechanisms that govern decisions regarding neuronal survival, growth, differentiation or apoptosis.

Spontaneous transformation of human adult nontumorigenic stem cells to cancer stem cells is driven by genomic instability in a human model of glioblastoma.

The presence of a CD133+/nestin+ population in brain tumors suggests that a normal neural stem cell may be the cell of origin for gliomas. We have identified human CD133-positive NSCs from adult glioma tissue and established them as long-term in vitro cultures human neuroglial culture (HNGC)-1. Replicative senescence in HNGC-1 led to a high level of genomic instability and emergence of a spontaneously immortalized clone that developed into cell line HNGC-2 with features of cancer stem cells (CSCs), which include the ability for self-renewal and the capacity to form CD133-positive neurospheres and develop intracranial tumors. The data from our study specify an important role of genomic instability in initiation of transformed state as well as its progression into highly tumorigenic CSCs. The activated forms of Notch and Hes isoforms were expressed in both non-neoplastic neural stem cells and brain tumor stem cells derived from it. Importantly, a significant overexpression of these molecules was found in the brain tumor stem cells. These findings suggest that this model comprised of HNGC-1 and HNGC-2 cells would be a useful system for studying pathways involved in self-renewal of stem cells and their transformation to cancer stem cells. Disclosure of potential conflicts of interest is found at the end of this article.

A unique model system for tumor progression in GBM comprising two developed human neuro-epithelial cell lines with differential transforming potential and coexpressing neuronal and glial markers.

The molecular mechanisms involved in tumor progression from a low-grade astrocytoma to the most malignant glioblastoma multiforme (GBM) have been hampered due to lack of suitable experimental models. We have established a model of tumor progression comprising of two cell lines derived from the same astrocytoma tumor with a set of features corresponding to low-grade glioma (as in HNGC-1) and high-grade GBM (as in HNGC-2). The HNGC-1 cell line is slow-growing, contact-inhibited, nontumorigenic, and noninvasive, whereas HNGC-2 is a rapidly proliferating, anchorage-independent, highly tumorigenic, and invasive cell line. The proliferation of cell lines is independent of the addition of exogenous growth factors. Interestingly, the HNGC-2 cell line displays a near-haploid karyotype except for a disomy of chromosome 2. The two cell lines express the neuronal precursor and progenitor markers vimentin, nestin, MAP-2, and NFP160, as well as glial differentiation protein S100beta. The HNGC-1 cell line also expresses markers of mature neurons like Tuj1 and GFAP, an astrocytic differentiation marker, hence contributing toward a more morphologically differentiated phenotype with a propensity for neural differentiation in vitro. Additionally, overexpression of epidermal growth factor receptor and c-erbB2, and loss of fibronectin were observed only in the HNGC-2 cell line, implicating the significance of these pathways in tumor progression. This in vitro model system assumes importance in unraveling the cellular and molecular mechanisms in differentiation, transformation, and gliomagenesis.

Differential expression of CD44(S) and variant isoforms v3, v10 in three-dimensional cultures of mouse melanoma cell lines.

Multi-cellular spheroids (MCS) generated from tumor cells serve as excellent in vitro models for understanding the mechanisms of tumor progression and micro-metastasis. We have compared the expression of molecular markers with reference to their growth as conventional adherent monolayers (2-D) and anchorage independent cultures (3-D) using two mouse melanoma cell lines, B16F10 and Clone M3. The two cell lines differed in their ability to form spheroids with respect to their aggregation potential, with B16F10 forming large clusters compared to Clone M3. A panel of molecular markers comprising cell adhesion molecules, cyclin dependent kinase inhibitors and members of the cadherin-catenin complex were analyzed by flow cytometry in 2-D and 3-D cultures. There was a distinct difference in the patterns of expression of CD44(S) and variant isoforms v3, v10 in spheroids compared to cells grown as monolayers in both cell lines. Also, there was an increase in cells positive for CDK inhibitor p27 in 3-D cultures from the B16F10 cell line. The expression of alpha and gamma catenin was down regulated in spheroids. As these molecules are implicated in the regulation of cell proliferation, alterations in the expression of these molecules in 3-D cultures compared to their 2-D counterparts suggests the importance of spheroids as experimental model for tumorigenesis.