From modulation of cellular plasticity to potentiation of therapeutic resistance: new and emerging roles of MYB transcription factors in human malignancies.

MYB transcription factors are encoded by a large family of highly conserved genes from plants to vertebrates. There are three members of the MYB gene family in human, namely, MYB, MYBL1, and MYBL2 that encode MYB/c-MYB, MYBL1/A-MYB, and MYBL2/B-MYB, respectively. MYB was the first member to be identified as a cellular homolog of the v-myb oncogene carried by the avian myeloblastosis virus (AMV) causing leukemia in chickens. Under the normal scenario, MYB is predominantly expressed in hematopoietic tissues, colonic crypts, and neural stem cells and plays a role in maintaining the undifferentiated state of the cells. Over the years, aberrant expression of MYB genes has been reported in several malignancies and recent years have witnessed tremendous progress in understanding of their roles in processes associated with cancer development. Here, we review various MYB alterations reported in cancer along with the roles of MYB family proteins in tumor cell plasticity, therapy resistance, and other hallmarks of cancer. We also discuss studies that provide mechanistic insights into the oncogenic functions of MYB transcription factors to identify potential therapeutic vulnerabilities.

MYB sustains hypoxic survival of pancreatic cancer cells by facilitating metabolic reprogramming.

Extensive desmoplasia and poor vasculature renders pancreatic tumors severely hypoxic, contributing to their aggressiveness and therapy resistance. Here, we identify the HuR/MYB/HIF1α axis as a critical regulator of the metabolic plasticity and hypoxic survival of pancreatic cancer cells. HuR undergoes nuclear-to-cytoplasmic translocation under hypoxia and stabilizes MYB transcripts, while MYB transcriptionally upregulates HIF1α. Upon MYB silencing, pancreatic cancer cells fail to survive and adapt metabolically under hypoxia, despite forced overexpression of HIF1α. MYB induces the transcription of several HIF1α-regulated glycolytic genes by directly binding to their promoters, thus enhancing the recruitment of HIF1α to hypoxia-responsive elements through its interaction with p300-dependent histone acetylation. MYB-depleted pancreatic cancer cells exhibit a dramatic reduction in tumorigenic ability, glucose-uptake and metabolism in orthotopic mouse model, even after HIF1α restoration. Together, our findings reveal an essential role of MYB in metabolic reprogramming that supports pancreatic cancer cell survival under hypoxia.

Ubiquitination of GRK2 Is Required for the ß-Arrestin-Biased Signaling Pathway of Dopamine D2 Receptors to Activate ERK Kinases.

A class-A GPCR dopamine D2 receptor (D2R) plays a critical role in the proper functioning of neuronal circuits through the downstream activation of both G-protein- and ß-arrestin-dependent signaling pathways. Understanding the signaling pathways downstream of D2R is critical for developing effective therapies with which to treat dopamine (DA)-related disorders such as Parkinson's disease and schizophrenia. Extensive studies have focused on the regulation of D2R-mediated extracellular-signal-regulated kinase (ERK) 1/2 signaling; however, the manner in which ERKs are activated upon the stimulation of a specific signaling pathway of D2R remains unclear. The present study conducted a variety of experimental techniques, including loss-of-function experiments, site-directed mutagenesis, and the determination of protein interactions, in order to investigate the mechanisms underlying ß-arrestin-biased signaling-pathway-mediated ERK activation. We found that the stimulation of the D2R ß-arrestin signaling pathway caused Mdm2, an E3 ubiquitin ligase, to move from the nucleus to the cytoplasm and interact with tyrosine phosphorylated G-protein-coupled receptor kinase 2 (GRK2), which was facilitated by Src, a non-receptor tyrosine kinase. This interaction led to the ubiquitination of GRK2, which then moved to the plasma membrane and interacted with activated D2R, followed by the phosphorylation of D2R as well as the mediation of ERK activation. In conclusion, Mdm2-mediated GRK2 ubiquitination, which is selectively triggered by the stimulation of the D2R ß-arrestin signaling pathway, is necessary for GRK2 membrane translocation and its interaction with D2R, which in turn mediates downstream ERK signaling. This study is primarily novel and provides essential information with which to better understand the detailed mechanisms of D2R-dependent signaling.

Mitochondrial Alterations in Prostate Cancer: Roles in Pathobiology and Racial Disparities.

Prostate cancer (PCa) affects millions of men worldwide and is a major cause of cancer-related mortality. Race-associated PCa health disparities are also common and are of both social and clinical concern. Most PCa is diagnosed early due to PSA-based screening, but it fails to discern between indolent and aggressive PCa. Androgen or androgen receptor-targeted therapies are standard care of treatment for locally advanced and metastatic disease, but therapy resistance is common. Mitochondria, the powerhouse of cells, are unique subcellular organelles that have their own genome. A large majority of mitochondrial proteins are, however, nuclear-encoded and imported after cytoplasmic translation. Mitochondrial alterations are common in cancer, including PCa, leading to their altered functions. Aberrant mitochondrial function affects nuclear gene expression in retrograde signaling and promotes tumor-supportive stromal remodeling. In this article, we discuss mitochondrial alterations that have been reported in PCa and review the literature related to their roles in PCa pathobiology, therapy resistance, and racial disparities. We also discuss the translational potential of mitochondrial alterations as prognostic biomarkers and as effective targets for PCa therapy.

Platinum-resistant ovarian cancer: From drug resistance mechanisms to liquid biopsy-based biomarkers for disease management.

Resistance to platinum-based chemotherapy is a major clinical challenge in ovarian cancer, contributing to the high mortality-to-incidence ratio. Management of the platinum-resistant disease has been difficult due to diverse underlying molecular mechanisms. Over the past several years, research has revealed several novel molecular targets that are being explored as biomarkers for treatment planning and monitoring of response. The therapeutic landscape of ovarian cancer is also rapidly evolving, and alternative therapies are becoming available for the recurrent platinum-resistant disease. This review provides a snapshot of platinum resistance mechanisms and discusses liquid-based biomarkers and their potential utility in effective management of platinum-resistant ovarian cancer.

Mitochondrial respiratory complexes: Significance in human mitochondrial disorders and cancers.

Mitochondria are pivotal organelles that govern cellular energy production through the oxidative phosphorylation system utilizing five respiratory complexes. In addition, mitochondria also contribute to various critical signaling pathways including apoptosis, damage-associated molecular patterns, calcium homeostasis, lipid, and amino acid biosynthesis. Among these diverse functions, the energy generation program oversee by mitochondria represents an immaculate orchestration and functional coordination between the mitochondria and nuclear encoded molecules. Perturbation in this program through respiratory complexes' alteration results in the manifestation of various mitochondrial disorders and malignancy, which is alarmingly becoming evident in the recent literature. Considering the clinical relevance and importance of this emerging medical problem, this review sheds light on the timing and nature of molecular alterations in various respiratory complexes and their functional consequences observed in various mitochondrial disorders and human cancers. Finally, we discussed how this wealth of information could be exploited and tailored to develop respiratory complex targeted personalized therapeutics and biomarkers for better management of various incurable human mitochondrial disorders and cancers.

Acidovorax kalamii sp. nov., isolated from a water sample of the river Ganges.

A Gram-stain-negative, rod-shaped, aerobic, straw yellow, motile strain, designated KNDSW-TSA6T, belonging to the genus Acidovorax, was isolated from a water sample of the river Ganges, downstream of the city of Kanpur, Uttar Pradesh, India. Cells were aerobic, non-endospore-forming and motile with single polar flagella. It differed from its phylogenetically related strains by phenotypic characteristics such as hydrolysis of urea, gelatin, casein and DNA, and the catalase reaction. The major fatty acids were C16 : 1ω7c/C16 : 1ω6c, C16 : 0 and C18 : 1ω7c/C18 : 1ω6c. Phylogenetic analysis based on 16S rRNA and housekeeping genes (gyrb, recA and rpoB gene sequences), confirmed its placement within the genus Acidovorax as a novel species. Strain KNDSW-TSA6T showed highest 16S rRNA sequence similarity to Acidovorax soli BL21T (98.9 %), Acidovorax delafieldii ATCC 17505T (98.8 %), Acidovorax temperans CCUG 11779T (98.2 %), Acidovorax caeni R-24608T (97.9 %) and Acidovorax radicis N35T (97.6 %). The digital DNA-DNA hybridization and average nucleotide identity values calculated from whole genome sequences between strain KNDSW-TSA6T and the two most closely related strains A. soli BL21T and A. delafieldii ATCC 17505T were below the threshold values of 70 and 95 % respectively. Thus, the data from the polyphasic taxonomic analysis clearly indicates that strain KNDSW-TSA6T represents a novel species, for which the name Acidovorax kalamii sp. nov. is proposed. The type strain is Acidovorax kalamii (=MTCC 12652T=KCTC 52819T=VTCC-B-910010T).

Thauera propionica sp. nov., isolated from downstream sediment sample of the river Ganges, Kanpur, India.

A Gram-stain-negative, non-endospore-producing, short-rod strain, KNDSS-Mac4T, was isolated from a downstream sediment sample of the river Ganges, Kanpur, India and studied by using the polyphasic taxonomic approach. 16S rRNA gene sequence analysis uncovered that the strain had similarity to species of the genus Thauera and formed a distinct phylogenetic cluster with Thauera humireducens KACC16524T. However, KNDSS-Mac4T showed closest phylogenetic affiliation to Thauera aminoaromatica DSM 14742T with 16S rRNA gene sequence similarity of 98.7 % followed by Thauera phenylacetica DSM 14743T (98.6 %), Thauera chlorobenzoica (98.2 %), T. humireducens KACC16524T (98.2 %), Thauera selenatis ATCC 55363T (98.2 %) and Thauera mechernichensis DSM 12266T (98.0 %). The digital DNA-DNA hybridization and average nucleotide identity values between strain KNDSS-Mac4T and the two most closely related taxa, T. aminoaromatica DSM 14742T and T. phenylacetica DSM 14743T, were 26.0, 26.7 and 84.0, 84.3 % respectively. Major lipids present were phosphatidylglycerol, three unknown aminophospholipids, phosphatidylmethylethanolamine, two unidentified lipids and Q-8 as the only ubiquonone. The major cellular fatty acids present were C16 : 1 ω6c/C16 : 1ω7c and C16 : 0. The DNA G+C content of strain KNDSS-Mac4T was 65.9 %. Based on data from phenotypic tests and the genotypic differences of strain KNDSS-Mac4T from its closest phylogenetic relatives, it is evident that this isolate should be regarded as a new species. It is proposed that strain KNDSS-Mac4T should be classified in the genus Thauera as a novel species, Thauerapropionica sp. nov. The type strain is KNDSS-Mac4T (=KCTC 52820T=VTCC-B-910017T).

Pseudomonas fluvialis sp. nov., a novel member of the genus Pseudomonas isolated from the river Ganges, India.

A bacterial strain, designated ASS-1T, was isolated and identified from a sediment sample of the river Ganges, Allahabad, India. The strain was Gram-stain-negative, formed straw-yellow pigmented colonies, was strictly aerobic, motile with a single polar flagellum, and positive for oxidase and catalase. The major fatty acids were C16 : 1ω7c/ 16 : 1 C16 : 1ω6c, C18 : 1ω7c and C16 : 0. Sequence analysis based on the 16S rRNA gene revealed that strain ASS-1T showed high similarity to Pseudomonas guguanensis CC-G9AT (98.2 %), Pseudomonas alcaligenes ATCC 14909T (98.2 %), Pseudomonas oleovorans DSM 1045T (98.1 %), Pseudomonas indolxydans IPL-1T (98.1 %) and Pseudomonas toyotomiensis HT-3T (98.0 %). Analysis of its rpoB and rpoD housekeeping genes confirmed its phylogenetic affiliation and showed identities lower than 93 % with respect to the closest relatives. Phylogenetic analysis based on the 16S rRNA, rpoB, rpoD genes and the whole genome assigned it to the genus Pseudomonas. The results of digital DNA-DNA hybridization based on the genome-to-genome distance calculator and average nucleotide identity revealed low genome relatedness to its close phylogenetic neighbours (below the recommended thresholds of 70 and 95 %, respectively, for species delineation). Strain ASS-1T also differed from the related strains by some phenotypic characteristics, i.e. growth at pH 5.0 and 42 °C, starch and casein hydrolysis, and citrate utilization. Therefore, based on data obtained from phenotypic and genotypic analysis, it is evident that strain ASS-1T should be regarded as a novel species within the genus Pseudomonas, for which the name Pseudomonasfluvialis sp. nov. is proposed. The type strain is ASS-1T (=KCTC 52437T=CCM 8778T).

Fictibacillus aquaticus sp. nov., isolated from downstream river water.

A Gram-stain-positive, facultatively anaerobic bacterial strain, GDSW-R2A3T, was isolated from a downstream water sample collected from the river Ganges, India. Analysis of the 16S rRNA gene sequence of strain GDSW-R2A3T revealed its affiliation to the family Bacillaceae. Further analysis using a polyphasic approach revealed that strain GDSW-R2A3T was most closely related to the genus Fictibacillus. Analysis of the almost-complete (1488 bp) 16S rRNA gene sequence of strain GDSW-R2A3T revealed the highest level of sequence similarity with Fictibacillus phosphorivorans CCM 8426T (98.3 %) and Fictibacillus nanhaiensis KCTC 13712T (98.3 %) followed by Fictibacillus barbaricus DSM 14730T (98.0 %). The digital DNA-DNA hybridization and average nucleotide identity (ANI) values between strain GDSW-R2A3T and the most closely related taxon, F. phosphorivorans CCM 8426T, were 20.3 and 78.2 %, respectively. The DNA G+C content of the strain was 44.2 mol%. The cell-wall amino acid was meso-diaminopimelic acid. Polar lipids present were phosphatidylglycerol, phosphatidylethanolamine, diphosphatidylglycerol, three aminophospholipids, two phospholipids and one unidentified lipid; the major menaquinone was MK-7; iso-C14 : 0, iso-C15 : 0 and anteiso-C15 : 0 were the major fatty acids. On the basis of the phenotypic, chemotaxonomic and phylogenetic data, it can be concluded that strain GDSW-R2A3T represents a novel species of the genus Fictibacillus, for which the name Fictibacillus aquaticus sp. nov. is proposed. The type strain is GDSW-R2A3T (=VTCC-B-910015T=CCM 8782T).

Comparative study of the molecular mechanisms underlying the G protein and ß-arrestin-dependent pathways that lead to ERKs activation upon stimulation by dopamine D2 receptor.

Dopamine D2 receptor (D2 R) has been shown to activate extracellular signal-regulated kinases (ERKs) via distinct pathways dependent on either G-protein or ß-arrestin. However, there has not been a systematic study of the regulatory process of D2 R-mediated ERKs activation by G protein- versus ß-arrestin-dependent signaling since D2 R stimulation of ERKs reflects the simultaneous action of both pathways. Here, we investigated that differential regulation of D2 R-mediated ERKs activation via these two pathways. Our results showed that G protein-dependent ERKs activation was transient, rapid, reached maximum level at around 2 min, and importantly, the activated ERKs were entirely confined to the cytoplasm. In contrast, ß-arrestin-dependent ERKs activation was more sustained, slower, reached maximum level at around 10 min, and phosphorylated ERKs translocated into the nucleus. Src was found to be commonly involved in both the G protein- and ß-arrestin-dependent pathway-mediated ERKs activation. Pertussis toxin Gi/o inhibitor, GRK2-CT, AG1478 epidermal growth factor receptor inhibitor, and wortmannin phosphoinositide 3-kinase inhibitor all blocked G protein-dependent ERKs activation. In contrast, GRK2 and ß-Arr2 played a main role in ß-arrestin-dependent ERKs activation. Receptor endocytosis showed minimal effect on the activation of ERKs mediated by both pathways. Furthermore, we found that the formation of a complex composed of phospho-ERKs, ß-Arr2, and importinß1 promoted the nuclear translocation of activated ERKs. The differential regulation of various cellular components, as well as temporal and spatial patterns of ERKs activation via these two pathways, suggest the existence of distinct physiological outcomes.

Profiling mitochondrial DNA mutations in tumors and circulating extracellular vesicles of triple-negative breast cancer patients for potential biomarker development.

Early detection and recurrence prediction are challenging in triple-negative breast cancer (TNBC) patients. We aimed to develop mitochondrial DNA (mtDNA)-based liquid biomarkers to improve TNBC management. Mitochondrial genome (MG) enrichment and next-generation sequencing mapped the entire MG in 73 samples (64 tissues and 9 extracellular vesicles [EV] samples) from 32 metastatic TNBCs. We measured mtDNA and cardiolipin (CL) contents, NDUFB8, and SDHB protein expression in tumors and in corresponding circulating EVs. We identified 168 nonsynonymous mtDNA mutations, with 73% (123/186) coding and 27% (45/168) noncoding in nature. Twenty percent of mutations were nucleotide transversions. Respiratory complex I (RCI) was the key target, which harbored 44% (74/168) of the overall mtDNA mutations. A panel of 11 hotspot mtDNA mutations was identified among 19%-38% TNBCs, which were detectable in the serum-derived EVs with 82% specificity. Overall, 38% of the metastatic tumor-signature mtDNA mutations were traceable in the EVs. An appreciable number of mtDNA mutations were homoplasmic (18%, 31/168), novel (14%, 23/168), and potentially pathogenic (9%, 15/168). The overall and RCI-specific mtDNA mutational load was higher in women with African compared to European ancestry accompanied by an exclusive abundance of respiratory complex (RC) protein NDUFB8 (RCI) and SDHB (RCII) therein. Increased mtDNA (p < 0.0001) content was recorded in both tumors and EVs along with an abundance of CL (p = 0.0001) content in the EVs. Aggressive tumor-signature mtDNA mutation detection and measurement of mtDNA and CL contents in the EVs bear the potential to formulate noninvasive early detection and recurrence prediction strategies.

Breast and Cervical cancer disparities in Alabama: current scenario, ongoing efforts to reduce the disparity gaps, and what more we could be doing.

Over the years, we have made considerable progress in our understanding of the biology of various cancers leading to advancements in their management strategies. Consequently, we have witnessed steady improvements in survival rates of cancer patients post-diagnosis. The progress; however, has been slow for some cancer types and the advances in cancer care have not benefited all the communities equally in the United States. The state of Alabama has one of the most diverse demographics in the country and as a result, we witness significant health disparities among our populations. Breast and cervical cancers are the two major cancer types that disparately affect the women in our state. Here, we describe the extent of disparities in the diagnosis and death rates from these cancers in the state of Alabama and discuss potential underlying causes affecting the health outcomes. We also discuss ongoing efforts undertaken to reduce the disparity gaps and provide a perspective for addressing these disparities more effectively.

Abundance and Diversity of Phages, Microbial Taxa, and Antibiotic Resistance Genes in the Sediments of the River Ganges Through Metagenomic Approach.

In this study, we have analyzed the metagenomic DNA from the pooled sediment sample of the river Ganges to explore the abundance and diversity of phages, microbial community, and antibiotic resistance genes (ARGs). Utilizing data from Illumina platform, 4,174 (∼0.0013%) reads were classified for the 285 different DNA viruses largely dominated by the group of 260 distinctive phages (3,602 reads, ∼86.3%). Among all, Microcystis (782 hits), Haemophilus (403), Synechococcus (386), Pseudomonas (279), Enterococcus (232), Bacillus (196), Rhodococcus (166), Caulobacter (163), Salmonella (146), Enterobacteria (143), Mycobacterium and (128) phages show the highest abundance and account for ∼90% of the total identified phages. In addition, we have also identified corresponding host pertaining to these phages. Mainly, Proteobacteria (∼69.3%) dominates the microbial population structure. Primarily, orders such as Caulobacterales (∼28%), Burkholderiales (∼13.9%), Actinomycetales (∼13.7%), and Pseudomonadales (∼7.5%) signify the core section. Furthermore, 21,869 (∼0.00695%) reads were classified in 20 ARG types (classes) and 240 ARGs (subtypes), among which 4 ARG types, namely multidrug resistance (12,041 reads, ∼55%), bacitracin (3,202 reads, ∼15%), macrolide-lincosamide-streptogramin (1,744 reads, ∼7.98%), and fosmidomycin (990 reads, ∼4.53%), have the highest abundance. Simultaneously, six resistance mechanisms were also recognized with the dominance of antibiotic efflux (72.8%, 15,919 reads). The results unveil the distribution of (pro)-phages; microbial community; and various ARGs in the Ganges river sediments.

Resistin: An inflammatory cytokine with multi-faceted roles in cancer.

Systemic and organ-confined inflammation has been associated with cancer development and progression. Resistin, initially described as an adipocyte-derived cytokine in mice, is mostly expressed by the macrophages in humans. It has potent pro-inflammatory properties, and its elevated serum levels are detected in cancer patients. Aberrant expression of resistin receptors is also reported in several malignancies and associated with aggressive clinicopathological features. Several lines of evidence demonstrate that resistin, acting through its different receptors, promotes tumor growth, metastasis, and chemoresistance by influencing a variety of cellular phenotypes as well as by modulating the tumor microenvironment. Racially disparate expression of resistin has also attracted much interest, considering prevalent cancer health disparities. This review discusses the aberrant expression of resistin and its receptors, its diverse downstream signaling and impact on tumor growth, metastasis, angiogenesis, and therapy resistance to support its clinical exploitation in biomarker and therapeutic development.

Production, purification and characterization of raw starch hydrolyzing thermostable acidic α-amylase from hot springs, India.

Alpha-amylase is an important hydrolytic enzyme used for various industrial processes. In the present study, Geobacillus bacterium (K1C), producing a thermostable α-amylase was isolated from Manikaran hot springs, India. We have purified and characterized the biochemical properties of α-amylase. The optimum temperature and pH for α-amylase activity was 80 °C and pH 6.0 respectively. The far-UV CD spectra of the enzyme indicated the presence of random coil conformation and showed an intermediate phase during temperature-induced unfolding. In the presence of substrate, thermostability of the α-amylase was increased as 50% initial activity was retained at 70 °C for 6 h and at 80 °C for 2 h. Moreover, the enzyme also showed remarkable pH stability as 90% of the initial activity was retained even after 48 h of incubation at pH 5.0, 6.0 and 7.0. Interestingly, amylase activity of the purified enzyme was Ca2+independent, whereas the complete inhibition of activity was observed in the presence of Cu2+, Pb2+, and Hg2+. The purified α-amylase was stable in the presence of detergents, organic solvents and Proteinase K. Furthermore, it exhibited the ability to hydrolyze raw starches (e.g. rice, wheat, corn, potato) efficiently; thus this enzyme has the potential to be used for industrial applications.