Our study investigated the relationship between MYC alterations and clinicopathological features in gastric cancers. We evaluated the effect of MYC mRNA expression and its protein immunoreactivity, as well as copy number variation, promoter DNA methylation, and point mutations, in 125 gastric adenocarcinoma and 67 paried non-neoplastic tissues. We observed that 77% of the tumors presented MYC immunoreactivity which was significantly associated with increased mRNA expression (p<0.05). These observations were associated with deeper tumor extension and the presence of metastasis (p<0.05). MYC protein expression was also more frequently observed in intestinal-type than in diffuse-type tumors (p<0.001). Additionally, MYC mRNA and protein expression were significantly associated with its copy number (p<0.05). The gain of MYC copies was associated with late-onset, intestinal-type, advanced tumor stage, and the presence of distant metastasis (p<0.05). A hypomethylated MYC promoter was detected in 86.4% of tumor samples. MYC hypomethylation was associated with diffuse-type, advanced tumor stage, deeper tumor extension, and the presence of lymph node metastasis (p<0.05). Moreover, eighteen tumor samples presented at least one known mutation. The presence of MYC mutations was associated with diffuse-type tumor (p<0.001). Our results showed that MYC deregulation was mainly associated with poor prognostic features and also reinforced the presence of different pathways involved in intestinal-type and diffuse-type gastric carcinogenesis. Thus, our findings suggest that MYC may be a useful marker for clinical stratification and prognosis.

MYC is an oncogene involved in cell cycle regulation, cell growth arrest, cell adhesion, metabolism, ribosome biogenesis, protein synthesis, and mitochondrial function. It has been described as a key element of several carcinogenesis processes in humans. Many studies have shown an association between MYC deregulation and gastric cancer. MYC deregulation is also seen in gastric preneoplastic lesions and thus it may have a role in early gastric carcinogenesis. Several studies have suggested that amplification is the main mechanism of MYC deregulation in gastric cancer.In the present review, we focus on the deregulation of the MYC oncogene in gastric adenocarcinoma c a r c i n o g e n e s i s , i n c l u d i n g i t s a s s o c i a t i o n w i t h Helicobacter pylori (H pylori ) MYC AND CANCERMYC gene was found to be the cellular homolog of retroviral v-myc oncogene about 30 years ago [12][13][14] . It is located on chromosomal region 8q24.1, has 3 exons [15,16] and encodes a nuclear phosphoprotein [17] . MYC has to heteromerize with MAX, a protein expressed constitutively, to acquire DNA-binding activity. MYC/MAX dimmers are made viable by a basic region helix-loop-helix leucine-zipper motif (bHLHZip), conserved sequences in the carboxyl terminus of both proteins. MYC/MAX dimmers bind to E-box sequence CACGTG in the promoters of specific target genes and stimulate their transcription [18] . MYC has an effect on up to about 15% of genes in genomes of many organisms, from flies to humans [19] . Groups of genes involved in cell cycle regulation, metabolism, ribosome biogenesis, protein synthesis, and mitochondrial function are over-represented in the Myc target gene network.MYC also consistently represses genes involved in cell growth arrest and cell adhesion [20] . Dominguez-Sola et al [21] recently showed that Myc interacts with the prereplicative complex and localizes to early sites of DNA synthesis. Thus, it also has a direct role in the control of DNA replication.MYC regulates transcription from its targets through several mechanisms, including recruitment of histone acetylases, chromatin modulating proteins, basal transcription factors and DNA methyltransferase [22][23][24][25][26] . Protein products of MYC target genes g o on to mediate the downstream effects of MYC on cell biology. MYC is then rapidly degraded, and the pathway switches to a transcriptionally repressive state when MAX dimerizes with a group of related bHLH-Zip proteins, the MAD family, that act as MYC antagonists [27] ( Figure 1).MYC expression might be regulated transcriptionally (initiation and elongation), post-transcriptionally (mRNA stability and translation) or post-translationally (protein stability) [28] . MYC is generally recognized as an important regulator of proliferation, growth, differentiation and apoptosis [29,30] . Therefore, it is also accepted that the deregulation of MYC expression is a major event in cancer pathogenesis or progression. Deregulated expression of a wild-type MYC protein is suff...

BackgroundMYC deregulation is a common event in gastric carcinogenesis, usually as a consequence of gene amplification, chromosomal translocations, or posttranslational mechanisms. FBXW7 is a p53-controlled tumor-suppressor that plays a role in the regulation of cell cycle exit and reentry via MYC degradation.MethodsWe evaluated MYC, FBXW7, and TP53 copy number, mRNA levels, and protein expression in gastric cancer and paired non-neoplastic specimens from 33 patients and also in gastric adenocarcinoma cell lines. We also determined the invasion potential of the gastric cancer cell lines.ResultsMYC amplification was observed in 51.5% of gastric tumor samples. Deletion of one copy of FBXW7 and TP53 was observed in 45.5% and 21.2% of gastric tumors, respectively. MYC mRNA expression was significantly higher in tumors than in non-neoplastic samples. FBXW7 and TP53 mRNA expression was markedly lower in tumors than in paired non-neoplastic specimens. Moreover, deregulated MYC and FBXW7 mRNA expression was associated with the presence of lymph node metastasis and tumor stage III-IV. Additionally, MYC immunostaining was more frequently observed in intestinal-type than diffuse-type gastric cancers and was associated with MYC mRNA expression. In vitro studies showed that increased MYC and reduced FBXW7 expression is associated with a more invasive phenotype in gastric cancer cell lines. This result encouraged us to investigate the activity of the gelatinases MMP-2 and MMP-9 in both cell lines. Both gelatinases are synthesized predominantly by stromal cells rather than cancer cells, and it has been proposed that both contribute to cancer progression. We observed a significant increase in MMP-9 activity in ACP02 compared with ACP03 cells. These results confirmed that ACP02 cells have greater invasion capability than ACP03 cells.ConclusionIn conclusion, FBXW7 and MYC mRNA may play a role in aggressive biologic behavior of gastric cancer cells and may be a useful indicator of poor prognosis. Furthermore, MYC is a candidate target for new therapies against gastric cancer.

Hepatitis E virus (HEV) is a common etiology of acute viral hepatitis worldwide. Recombinant HEV vaccines have been developed, but only one is commercially available and licensed in China since 2011. Epidemiological studies have identified genotype 3 as the major cause of chronic infection in immunocompromised individuals. Ribavirin has been shown to be effective as a monotherapy to induce HEV clearance in chronic patients who have undergone solid organ transplant (SOT) under immunosuppressive therapy. Efforts and improvements in prevention and control have been made to reduce the instances of acute and chronic hepatitis E in endemic and nonendemic countries. However, this review shows that further studies are required to demonstrate the importance of preventive vaccination and treatment worldwide, with emphasis on hepatitis E infection in the public health system.

A significant proportion of patients with oestrogen receptor (ER) positive breast cancers (BC) develop resistance to endocrine treatments (ET) and relapse with metastatic disease. Here we perform whole exome sequencing and gene expression analysis of matched primary breast tumours and bone metastasis-derived patient-derived xenografts (PDX). Transcriptomic analyses reveal enrichment of the G2/M checkpoint and up-regulation of Polo-like kinase 1 (PLK1) in PDX. PLK1 inhibition results in tumour shrinkage in highly proliferating CCND1 -driven PDX, including different RB-positive PDX with acquired palbociclib resistance. Mechanistic studies in endocrine resistant cell lines, suggest an ER-independent function of PLK1 in regulating cell proliferation. Finally, in two independent clinical cohorts of ER positive BC, we find a strong association between high expression of PLK1 and a shorter metastases-free survival and poor response to anastrozole. In conclusion, our findings support clinical development of PLK1 inhibitors in patients with advanced CCND1 -driven BC, including patients progressing on palbociclib treatment.

Gastric cancer is the fourth most frequent type of cancer and the second most frequent cause of cancer mortality worldwide. Only a modest number of gastric carcinoma cell lines have been isolated thus far. Here we describe the establishment and cytogenetic characterization of three new gastric cancer cell lines obtained from primary gastric adenocarcinoma (ACP02 and ACP03) and cancerous ascitic fluid (AGP01) of individuals from northern Brazil. ACP02, ACP03, and AGP01 cell lines are presently in the 60th passage. The cell lines grew in a disorganized single layer with some agglomerations and heterogeneous divisions (bipolar and multipolar). All cell lines exhibited a composite karyotype with several clonal chromosome alterations. Trisomy 8 was the most frequent alteration. Chromosome 8 aneusomy was confirmed by fluorescence in situ hybridization. All cell lines also exhibited trisomy 7 and deletion of chromosome arm 17p. These results suggest that, although frequent chromosome alterations are commonly observed due to culture process, the ACP02, ACP03, and AGP01 cell lines and primary gastric cancer from individuals of northern Brazil share genetic alterations, supporting use of these cell lines as a model of gastric carcinogenesis in this population.

Breast cancer is a complex disease, with heterogeneous clinical evolution. Several analyses have been performed to identify the risk factors for breast cancer progression and the patients who respond best to a specific treatment. We aimed to evaluate whether the hormone receptor expression, HER2 and MYC genes and their protein status, and KRAS codon 12 mutations may be prognostic or predictive biomarkers of breast cancer. Protein, gene and mutation status were concomitantly evaluated in 116 breast tumors from women who underwent neoadjuvant chemotherapy with doxorubicin plus cyclophosphamide. We observed that MYC expression was associated with luminal B and HER2 overexpression phenotypes compared to luminal A (p<0.05). The presence of MYC duplication or polysomy 8, as well as KRAS mutation, were also associated with the HER2 overexpression subtype (p<0.05). MYC expression and MYC gain were more frequently observed in early-onset compared to late-onset tumors (p<0.05). KRAS mutation was a risk factor of grade 3 tumors (p<0.05). A multivariate logistic regression demonstrated that MYC amplification defined as MYC/nucleus ratio of ≥2.5 was a protective factor for chemotherapy resistance. On the other hand, age and grade 2 tumors were a risk factor. Additionally, luminal B, HER2 overexpression, and triple-negative tumors presented increased odds of being resistant to chemotherapy relative to luminal A tumors. Thus, breast tumors with KRAS codon 12 mutations seem to present a worse prognosis. Additionally, MYC amplification may help in the identification of tumors that are sensitive to doxorubicin plus cyclophosphamide treatment. If confirmed in a large set of samples, these markers may be useful for clinical stratification and prognosis.

Combination of CDK4/6 inhibitors and endocrine therapy improves clinical outcome in advanced oestrogen receptor (ER)positive breast cancer, however relapse is inevitable. Here, we show in model systems that other than loss of RB1 few genecopy number (CN) alterations are associated with irreversible-resistance to endocrine therapy and subsequent secondary resistance to palbociclib. Resistance to palbociclib occurred as a result of tumour cell rewiring leading to increased expression of EGFR, MAPK, CDK4, CDK2, CDK7, CCNE1 and CCNE2. Resistance altered the ER genome wide-binding pattern, leading to decreased expression of 'classical' oestrogen-regulated genes and was accompanied by reduced sensitivity to fulvestrant and tamoxifen. Persistent CDK4 blockade decreased phosphorylation of tuberous sclerosis complex 2 (TSC2) enhancing EGFR signalling, leading to the rewiring of ER. Kinome-knockdown confirmed dependency on ERBBsignalling and G2/M-checkpoint proteins such as WEE1, together with the cell cycle master regulator, CDK7. Noteworthy, sensitivity to CDK7 inhibition was associated with loss of ER and RB1 CN. Overall, we show that resistance to CDK4/6 inhibitors is dependent on kinase rewiring and the redeployment of signalling cascades previously associated with endocrine resistance and highlights new therapeutic networks that can be exploited upon relapse after CDK4/6 inhibition.