Expression of the high mobility group proteins HMGI(Y) correlates with malignant progression in Barrett's metaplasia

The Prominent Role of HMGA Proteins in the Early Management of Gastrointestinal Cancers

GI tumors represent a heterogeneous group of neoplasms concerning their natural history and molecular alterations harbored. Nevertheless, these tumors share very high incidence and mortality rates worldwide and patients' poor prognosis. Therefore, the identification of specific biomarkers could increase the development of personalized medicine, in order to improve GI cancer management. In this sense, HMGA family members (HMGA1 and HMGA2) comprise an important group of genes involved in the genesis and progression of malignant tumors. Additionally, it has also been reported that HMGA1 and HMGA2 display an important role in the detection and progression of GI tumors. In this way, HMGA family members could be used as reliable biomarkers able to efficiently track not only the tumor per se but also the main risk conditions related with their development of GI cancers in the future. Finally, it shall be a promising option to revert the current scenario, once HMGA genes and proteins could represent a convergence point in the complex landscape of GI tumors.

Lessons from the Crypt: HMGA1-Amping up Wnt for Stem Cells and Tumor Progression

High mobility group A1 (HMGA1) chromatin remodeling proteins are enriched in aggressive cancers and stem cells, although their common function in these settings has remained elusive until now. Recent work in murine intestinal stem cells (ISC) revealed a novel role for Hmga1 in enhancing self-renewal by amplifying Wnt signaling, both by inducing genes expressing Wnt agonist receptors and Wnt effectors. Surprisingly, Hmga1 also "builds" a stem cell niche by upregulating Sox9, a factor required for differentiation to Paneth cells; these cells constitute an epithelial niche by secreting Wnt and other factors to support ISCs. HMGA1 is also highly upregulated in colon cancer compared with nonmalignant epithelium and SOX9 becomes overexpressed during colon carcinogenesis. Intriguingly, HMGA1 is overexpressed in diverse cancers with poor outcomes, where it regulates developmental genes. Similarly, HMGA1 induces genes responsible for pluripotency and self-renewal in embryonic stem cells. These findings demonstrate that HMGA1 maintains Wnt and other developmental transcriptional networks and suggest that HMGA1 overexpression fosters carcinogenesis and tumor progression through dysregulation of these pathways. Studies are now needed to determine more precisely how HMGA1 modulates chromatin structure to amplify developmental genes and how to disrupt this process in cancer therapy. Cancer Res; 78(8); 1890-7. ©2018 AACR.

HMGA2, but not HMGA1, is overexpressed in human larynx carcinomas

AIMS

Malignant tumours from the upper aerodigestive tract are grouped collectively in the class of head and neck squamous cell carcinoma (HNSCC). The head and neck tumours were responsible for more than 500 000 cancer cases in 2012, accounting for the sixth highest incidence rate and mortality worldwide among all tumour types. Laryngeal squamous cell carcinoma (LSCC) possesses the second highest incidence rate among all HNSCC. Despite significant advances in surgery and radiotherapy during the last few decades, no treatment has been shown to achieve a satisfactory therapeutic outcome and the mortality rate of LSCC is still high, with a 5-year survival rate of 64%. Therefore, further investigations are required to identify the pathogenesis of LSCC.

METHODS AND RESULTS

In order to search for new LSCC biomarkers, we have analysed the expression of the HMGA family members, HMGA1 and HMGA2, by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunohistochemistry. HMGA proteins are usually absent in the healthy adult tissues. In contrast, their constitutive expression is a feature of several neoplasias, being associated with a highly malignant phenotype and reduced survival. Here, we report HMGA2 overexpression in larynx carcinomas. Conversely, HMGA1 does not show any differences in its expression between normal and carcinoma tissues. Interestingly, HMGA2 overexpression appears associated with that of two HMGA1-pseudogenes, HMGA1P6 and HMGA1P7, acting as a sponge for HMGA1- and HMGA2-targeting microRNAs and involved in several human cancers.

CONCLUSIONS

Therefore, HMGA2 overexpression appears to be a strong feature of larynx carcinoma, supporting its detection as a valid tool for the diagnosis of these malignancies.

High mobility group A1 enhances tumorigenicity of human cholangiocarcinoma and confers resistance to therapy

High mobility group A1 (HMGA1) protein has been described to play an important role in numerous types of human carcinoma. By the modulation of several target genes HMGA1 promotes proliferation and epithelial-mesenchymal transition of tumor cells. However, its role in cholangiocarcinoma (CCA) has not been addressed yet. Therefore, we determined HMGA1 mRNA expression in CCA samples in a transcriptome array (n = 104) and a smaller cohort (n = 13) by qRT-PCR. Protein expression was evaluated by immunohistochemistry in a tissue microarray (n = 67). In addition, we analyzed changes in cell proliferation, colony formation, response to gemcitabine treatment, and target gene expression after modulation of HMGA1 expression in CCA cell lines. mRNA levels of HMGA1 were found to be upregulated in 15-62% depending on the cohort analyzed. Immunohistochemistry showed HMGA1 overexpression in 51% of CCA specimens. Integration with clinico-pathological data revealed that high HMGA1 expression was associated with reduced time to recurrence and a positive lymph node status in extrahepatic cholangiocellular carcinoma. In vitro experiments showed that overexpression of HMGA1 in CCA cell lines promoted cell proliferation, whereas its suppression reduced growth rate. HMGA1 further promoted colony formation in an anchorage independent growth and conferred resistance to gemcitabine treatment. Finally, HMGA1 modulated the expression of two genes involved in CCA carcinogenesis, iNOS and ERBB2. In conclusion, our findings indicate that HMGA1 expression is increased in a substantial number of CCA specimens. HMGA1 further promotes CCA tumorigenicity and confers resistance to chemotherapy.

Fra-1 Regulates the Expression of HMGA1, Which is Associated with a Poor Prognosis in Human Esophageal Squamous Cell Carcinoma

BACKGROUND

The expression of Fos-related antigen 1 (Fra-1) affects tumor progression, migration, and invasion. In this study, we identified the genes regulated by Fra-1 in esophageal squamous cell carcinoma (ESCC).

METHODS

We constructed Fra-1 knockdown models via the transfection of small interfering RNA (siRNA) into ESCC cell lines (TE10, TE11). The expression levels of the genes in the knockdown models were analyzed using a microarray and a Biobase Upstream Analysis, while the expression levels of the candidate genes in the primary tumors of surgical specimens obtained from ESCC patients were determined using real-time polymerase chain reaction (PCR) and immunohistochemical staining. The clinicopathological features were then analyzed.

RESULTS

The Biobase Upstream Analysis showed the high-mobility-group protein-1 (HMGA1) to be a significant gene regulated by Fra-1. Actual binding of Fra-1 to the promotor region of HMGA1 was revealed in subsequent chromatin immunoprecipitation PCR experiments. Patients with a positive HMGA1 expression had a poor prognosis, and a multivariate analysis demonstrated a positive HMGA1 expression to be a significant independent prognostic factor.

CONCLUSION

HMGA1 is regulated by Fra-1 in ESCC, and the HMGA1 expression is significantly associated with a poor prognosis in ESCC patients. Downregulation of the HMGA1 expression may become a practical treatment strategy against ESCC in the future.

High Mobility Group A proteins in esophageal carcinomas

We have recently shown that HMGA2 is overexpressed in esophageal squamous cell carcinoma (ESCC) and its detection allows to discriminate between cancer and normal surrounding tissue proposing HMGA2 as a novel diagnostic marker. Interestingly, esophageal adenocarcinoma shows an opposite behavior with the overexpression of HMGA1 but not HMGA2. Moreover, we show that the suppression of HMGA2 in 2 ESCC cell lines reduces the malignant phenotype. Then, this paper highlights a differential induction of the HMGA proteins, depending on the cancer histological type, and reinforces the perspective of an innovative esophageal cancer therapy based on the suppression of the HMGA protein function and/or expression.

Pancreatic cyst fluid concentration of high-mobility group A2 protein acts as a differential biomarker of dysplasia in intraductal papillary mucinous neoplasm

BACKGROUND AND AIMS

No reliable cyst fluid biomarkers exist that allow preoperative identification of patients with intraductal papillary mucinous neoplasms (IPMNs) and high-risk pathology. High-mobility group (HMG) A2 protein has been demonstrated to be a biomarker of dysplasia in IPMNs. It is unknown whether HMGA2 protein is present in the cyst fluid from IPMNs. The aims of this study were to determine whether HMGA2 protein is present in the cyst fluid of IPMNs and demonstrate whether HMGA2 protein concentration correlates with the degree of dysplasia.

METHODS

Patients with surgically resected IPMNs and banked pancreatic cyst fluid were identified. Low-risk IPMNs (low-grade [LGD] or moderate dysplasia [MD]) and high-risk IPMNs (high-grade dysplasia [HGD] or invasive cancer) were identified. Pancreatic cyst fluid concentrations of HMGA2 protein were measured via enzyme-linked immunosorbent assay.

RESULTS

Samples from 31 patients were analyzed. HMGA2 protein was detected in the cyst fluid of 30 of 31 specimens (97%). Median cyst fluid HMGA2 protein concentration (ng/mL) was as follows: LGD, 0.6 (interquartile range [IQR] 0.35-0.6); MD, 1.55 (IQR 0.65-2.7); HGD, 4.2 (IQR 1.7-9.2) (P < .05). The median HMGA2 protein concentration was significantly higher in the HGD group (4.2 ng/mL, IQR 1.7-9.2) compared with the concentration in the low-risk group (1.1 ng/mL, IQR 0.6-2.7, P = .03).

CONCLUSION

HMGA2 protein is present in IPMN cyst fluid. Significantly higher concentrations of cyst fluid HMGA2 protein are found in IPMNs with HGD compared with lesions with LGD or MD. Cyst fluid concentrations of HMGA2 protein may thus serve as a biomarker to differentiate patients with high-risk IPMNs from those with low-risk IPMNs.

High mobility group a proteins as tumor markers

Almost 30 years ago, overexpression of HMGA proteins was associated with malignant phenotype of rat thyroid cells transformed with murine retroviruses. Thereafter, several studies have analyzed HMGA expression in a wide range of human neoplasias. Here, we summarize all these results that, in the large majority of the cases, confirm the association of HMGA overexpression with high malignant phenotype as outlined by chemoresistance, spreading of metastases, and a global poor survival. Even though HMGA proteins’ overexpression indicates a poor prognosis in almost all malignancies, their detection may be particularly useful in determining the prognosis of breast, lung, and colon carcinomas, suggesting for the treatment a more aggressive therapy. In particular, the expression of HMGA2 in lung carcinomas is frequently associated with the presence of metastases. Moreover, recent data revealed that often the cause for the high HMGA proteins levels detected in human malignancies is a deregulated expression of non-coding RNA. Therefore, the HMGA proteins represent tumor markers whose detection can be a valid tool for the diagnosis and prognosis of neoplastic diseases.

Thymidylate synthase polymorphisms, folate and B-vitamin intake, and risk of colorectal adenoma

The effects of polymorphisms in genes coding for key folate metabolism enzymes such as thymidylate synthetase (TS) on colorectal neoplasia risk are likely to be influenced by gene–gene and gene–nutrient interactions. We investigated the combined effects of three polymorphisms in the TS gene region, TSER, TS 3R G>C, and TS 1494del6, dietary intakes of folate and other B vitamins, and genotype for other folate metabolism variants, in a colorectal adenoma (CRA) case–control study. Individuals homozygous for TS 1494del6 del/del were at significantly reduced CRA risk compared to those with either ins/del or ins/ins genotypes (odds ratio 0.52; 95% confidence interval: 0.31–0.85, P=0.009). We also observed evidence of interactions between TS 1494del6 genotype and intake of folate, and vitamins B₆ and B₁₂, and MTHFR C677T genotype, with the reduction in risk in del/del homozygotes being largely confined to individuals with high nutrient intakes and MTHFR 677CC genotype (P_interaction=0.01, 0.006, 0.03, and 0.07, respectively). TSER genotype, when considered either alone or in combination with TS 3R G>C genotype, did not significantly influence CRA risk. These findings support a role for TS in colorectal carcinogenesis, and provide further evidence that functional polymorphisms in folate metabolism genes act as low-risk alleles for colorectal neoplasia and participate in complex gene–gene and gene–nutrient interactions.

Increased expression of high mobility group A proteins in lung cancer

High mobility group A (HMGA) proteins play an important role in the regulation of transcription, differentiation, and neoplastic transformation. In this work, the expression of HMGA 1 and 2 in 152 lung carcinomas of mainly non-small-cell histological type has been studied by immunohistochemistry in order to evaluate their feasibility as lung cancer markers. In 17 lung cancer cases, the related bronchial epithelial changes were also studied for HMGA1 and 2 expression. RNA expression of HMGA1a and b isoforms and of HMGA2 was determined by real-time semi-quantitative RT-PCR in 23 lung carcinomas. High expression of HMGA1 and HMGA2 at both mRNA and protein levels was detected in lung carcinomas, compared with normal lung tissue. Nuclear immunostaining for HMGA1 and 2 proteins also occurred in hyperplastic, metaplastic, and dysplastic bronchial epithelium. Increased nuclear expression of HMGA1 and 2 correlated with poor survival (for adenocarcinomas, HMGA1, p=0.006; HMGA2, p=0.05). While the expression of HMGA2 was significantly associated with cell proliferation (p=0.008), HMGA1 expression did not show any association with proliferation or apoptotic index. Sequencing of HMGA2 transcripts from tumours with very high expression showed a normal full-length transcript. As HMGA proteins were expressed in about 90% of lung carcinomas and their expression was inversely associated with survival, they may provide useful markers for lung cancer diagnosis and prognosis.

Pharmacogenetics of folate-related drug targets in cancer treatment

Folate metabolism is the target of two major drug groups: folate antagonists (for example, methotrexate) and thymidylate synthase inhibitors (for example, 5-fluorouracil). These agents are used in the treatment of cancer, as well as for other conditions, such as rheumatoid arthritis. High-dose cancer treatment protocols can induce a state of acute folate depletion which may lead to significant treatment-related toxicity. Polymorphisms in folate-metabolizing enzymes may modify the therapeutic effectiveness and toxicity of these drugs. This review briefly summarizes the drugs targeting the folate pathway and describes common polymorphisms in folate-metabolizing enzymes and transport proteins. Pharmacogenetic studies investigating folate-related drug targets in the treatment of colorectal cancers and hematologic malignancies will subsequently be discussed. Findings to date illustrate a potential for targeting therapy based on patients' genotypes, in order to improve outcomes and reduce toxicity. However, larger, well-designed studies are needed to confirm these early findings.