We review the most well characterized long non‐coding RNAs (lncRNAs) with important roles in hallmarks of cancer, additionally including lncRNAs with a higher potential for clinical application. LncRNAs are transcripts larger than 200 nucleotides in length that do not appear to have protein‐coding potential, although some of those may produce small functional peptides. These transcripts have attracted significant attention from researchers as a result of their role in genetic regulation, including epigenetic, transcriptional and post‐transcriptional regulation, being involved in numerous biological processes, as well as being associated with multifactorial diseases, including tumorigenesis. The hallmarks of cancer include sustaining proliferative signaling, evading growth suppressors, resisting cell death, enabling replicative immortality, inducing angiogenesis and activating invasion/metastasis. Additionally, genome instability, inflammation, reprogramming of energy metabolism and evading immune destruction and lncRNAs are implicated in all hallmarks of cancer. Based on the great number of studies describing lncRNAs associated with diverse aspects of most tumor types, lncRNAs have essential roles in potentially all biological features of cancer cells and show great utility as diagnostic and prognostic markers, as exemplified by PCA3 lncRNA detection in prostate cancer diagnosis.

Multifactorial diseases such as cancer, cardiovascular conditions and neurological, immunological and metabolic disorders are a group of diseases caused by the combination of genetic and environmental factors. High-throughput RNA sequencing (RNA-seq) technologies have revealed that less than 2% of the genome corresponds to protein-coding genes, although most of the human genome is transcribed. The other transcripts include a large variety of non-coding RNAs (ncRNAs), and the continuous generation of RNA-seq data shows that ncRNAs are strongly deregulated and may be important players in pathological processes. A specific class of ncRNAs, the long non-coding RNAs (lncRNAs), has been intensively studied in human diseases. For clinical purposes, lncRNAs may have advantages mainly because of their specificity and differential expression patterns, as well as their ideal qualities for diagnosis and therapeutics. Multifactorial diseases are the major cause of death worldwide and many aspects of their development are not fully understood. Recent data about lncRNAs has improved our knowledge and helped risk assessment and prognosis of these pathologies. This review summarizes the involvement of some lncRNAs in the most common multifactorial diseases, with a focus on those with published functional data.

BackgroundPathophysiological mechanisms are still incompletely understood for leprosy, an urgent public health issue in Brazil. Complement receptor 1 (CR1) binds complement fragments C3b/C4b deposited on mycobacteria, mediating its entrance in macrophages. We investigated CR1 polymorphisms, gene expression and soluble CR1 levels in a case-control study with Brazilian leprosy patients, aiming to understand the role of this receptor in differential susceptibility to the disease.MethodologyNine polymorphisms were haplotyped by multiplex PCR-SSP in 213 leprosy patients (47% multibacillary) and 297 controls. mRNA levels were measured by qPCR and sCR1 by ELISA, in up to 80 samples.Principal findingsIndividuals with the most common recombinant haplotype harboring rs3849266*T in intron 21 and rs3737002*T in exon 26 (encoding p.1408Met of the York Yka+ antigen), presented twice higher susceptibility to leprosy (OR = 2.43, p = 0.017). Paucibacillary patients with these variants presented lower sCR1 levels, thus reducing the anti-inflammatory response (p = 0.040 and p = 0.046, respectively). Furthermore, the most ancient haplotype increased susceptibility to the multibacillary clinical form (OR = 3.04, p = 0.01) and presented the intronic rs12034383*G allele, which was associated with higher gene expression (p = 0.043), probably increasing internalization of the parasite. Furthermore, there was an inverse correlation between the levels of sCR1 and mannose-binding lectin (initiator molecule of the lectin pathway of complement, recognized by CR1) (R = -0.52, p = 0.007).ConclusionsThe results lead us to suggest a regulatory role for CR1 polymorphisms on mRNA and sCR1 levels, with haplotype-specific effects increasing susceptibility to leprosy, probably by enhancing parasite phagocytosis and inflammation.

Pemphigus foliaceus is an autoimmune disease that is sporadic around the world but endemic in Brazil, where it is known as fogo selvagem (FS). Characterized by autoantibodies against the desmosomal cadherin desmoglein 1, FS causes painful erosions, and crusts that may be widespread. The recognition of antigens, including exposed sugar moieties, activates the complement system. Complement receptor 1 (CR1, CD35), which is responsible for the Knops blood group on erythrocytes (York and McCoy antigens), is also expressed by antigen-presenting cells. This regulates the complement system by removing opsonized antigens, blocking the final steps of the complement cascade. Membrane-bound CR1 also fosters antigen presentation to B cells, whereas soluble CR1 has anti-inflammatory properties. CR1 gene polymorphisms have been associated with susceptibility to complex diseases. In order to investigate the association of CR1 polymorphisms with FS susceptibility, we developed a multiplex sequence-specific assay to haplotype eleven polymorphisms in up to 367 FS patients and 242 controls from an endemic area and 289 from a non-endemic area. We also measured soluble CR1 (sCR1) in the serum of 53 FS patients and 27 controls and mRNA levels in the peripheral blood mononuclear cells of 63 genotyped controls. The haplotypes CR1*3B2B (with the York antigen–encoded by p.1408Met) and CR1*3A2A (with p.1208Arg) were associated with protection against FS (OR = 0.57, P = 0.027, and OR = 0.46, P = 0.014, respectively). In contrast, the CR1*1 haplotype (with the McCoy antigen – encoded by p.1590Glu) was associated with FS susceptibility (OR = 4.97, P < 0.001). Heterozygote rs12034383*A/G individuals presented higher mRNA expression than homozygotes with the G allele (P = 0.04). The lowest sCR1 levels occurred in patients with active disease before treatment (P = 0.036). Patients in remission had higher levels of sCR1 than did healthy controls (P = 0.013). Among those under treatment, patients with localized lesions also presented higher sCR1 levels than those with generalized lesions (P = 0.0073). In conclusion, the Knops blood group seems to modulate susceptibility to the disease. Furthermore, corticosteroid treatment might increase sCR1 serum levels, and higher levels may play an anti-inflammatory role in patients with FS, limiting the distribution of lesions. Based on these results, we suggest CR1 as a potential new therapeutic target for the treatment of FS.

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