Loss of MSH2 protein expression is a risk factor in early stage cervical cancer

Expression patterns of mismatch repair proteins in cervical cancer uncover independent prognostic value of MSH-2

OBJECTIVE

Although early-detected cervical cancer is associated with good survival, the prognosis for late-stage disease is poor and treatment options are sparse. Mismatch repair deficiency (MMR-D) has surfaced as a predictor of prognosis and response to immune checkpoint inhibitor(s) in several cancer types, but its value in cervical cancer remains unclear. This study aimed to define the prevalence of MMR-D in cervical cancer and assess the prognostic value of MMR protein expression.

METHODS

Expression of the MMR proteins MLH-1, PMS-2, MSH-2, and MSH-6 was investigated by immunohistochemical staining in a prospectively collected cervical cancer cohort (n=508) with corresponding clinicopathological and follow-up data. Sections were scored as either loss or intact expression to define MMR-D, and by a staining index, based on staining intensity and area, evaluating the prognostic potential. RNA and whole exome sequencing data were available for 72 and 75 of the patients and were used for gene set enrichment and mutational analyses, respectively.

RESULTS

Five (1%) tumors were MMR-deficient, three of which were of neuroendocrine histology. MMR status did not predict survival (HR 1.93, p=0.17). MSH-2 low (n=48) was associated with poor survival (HR 1.94, p=0.02), also when adjusting for tumor stage, tumor type, and patient age (HR 2.06, p=0.013). MSH-2 low tumors had higher tumor mutational burden (p=0.003) and higher frequency of (frameshift) mutations in the double-strand break repair gene RAD50 (p<0.01).

CONCLUSION

MMR-D is rare in cervical cancer, yet low MSH-2 expression is an independent predictor of poor survival.

Role of MLH1 and MSH2 deficiency in the development of tumorigenesis and chemo-tolerance of cervical Carcinoma: Clinical implications

Cervical cancer (CACX) is one of the top causes of cancer death in women globally. The involvement of several cellular pathways in carcinogenesis is still poorly understood. Here, we focused to evaluate the contributory role of Mismatch Repair (MMR) pathway genes-MLH1 and MSH2 in CACX and their association with chemo-tolerance of the disease. For this purpose, molecular profiles (expression/promoter methylation/deletion) of the genes were analysed in both normal cervical epithelium and tumour tissue, also validated in in-silico dataset as well. Later on, prognostic importance of the genes was identified through analysis of their methylation/expression status in plasma DNA of circulating tumour cells (CTCs) and cisplatin-tolerant CACX cell lines respectively. It was found that the expression profile of MLH1 and MSH2 genes was considerably reduced from undifferentiated basal-parabasal layers of normal cervical epithelium towards progression of the disease. Further analysis showed that frequent deletion [34-48%] and promoter methylation events [28-46%] of the genes were the plausible reasons for their reduced expression during tumorigenesis. Incidentally, the prevalence of MLH1 [32%] and MSH2 [27%] promoter methylation found in CTCs of plasma of the clinically advanced CACX patients implicated their prognostic importance of the disease. In addition, the patients having high alterations of those genes resulted in poor patient outcomes even after the therapy. In in-depth analysis of this result in cisplatin-tolerant CACX cell lines, we discovered that increased promoter methylation frequency of those genes at higher concentrations of cisplatin and gradual accumulation of the cells in the G2/M phase of the cell cycle were the rational causes for their reduced expression and MMR deficiency in the system. Hence, it is possible to conclude that the gradual down-regulation of MLH1 and MSH2 proteins may be a key event for MMR pathway inactivation in CACX. This might also be associated with chemo-tolerance and overall poor survival among the patients.

Long noncoding RNA RP11-241J12.3 targeting pyruvate carboxylase promotes hepatocellular carcinoma aggressiveness by disrupting pyruvate metabolism and the DNA mismatch repair system

Accumulating evidence indicates that hepatitis B virus X protein (HBx) plays a key role in HBV-related hepatocellular carcinoma (HCC) aggressiveness; however, the underlying mechanisms are not entirely clear. Long non-coding RNAs (lncRNAs), which participate in the regulation of diverse biological processes, may be critical for the function of HBx. Our research indicated that HBx induced changes in the expression of numerous lncRNAs and implicated the novel lncRNA RP11-241J12.3 in HBx-mediated HCC aggressiveness. Although RP11-241J12.3 expression was downregulated in transient HBx-expressing HCC cells (similar to the early stage of HBV infection), its oncogenic properties remained. The results showed that RP11-241J12.3 not only accelerated DNA synthesis and upregulated the expression of pyruvate carboxylase (PC) and MSH3, which is a key protein in pyruvate metabolism and DNA mismatch repair (MMR), but also promoted tumor growth in vitro and in vivo, thus promoting HCC aggressiveness. More importantly, we revealed that RP11-241J12.3 may interact with PC and identified its location in the cytoplasm close to the nucleus using fluorescence in situ hybridization (FISH). We also observed RP11-241J12.3 expression was upregulated in HCC tissues compared with the paracarcinomatous tissues. Furthermore, RP11-241J12.3 expression levels showed a close relationship with clinical stage and tumor size and that low RP11-241J12.3 expression was significantly correlated with longer HCC patient survival. These results further our understanding of the lncRNAs regulated by HBx in HCC, and provide evidence that dysregulation of RP11-241J12.3 contributes to HCC aggressiveness.

Identification of Potential Driver Genes Based on Multi-Genomic Data in Cervical Cancer

Background: Cervical cancer became the third most common cancer among women, and genome characterization of cervical cancer patients has revealed the extensive complexity of molecular alterations. However, identifying driver mutation and depicting molecular classification in cervical cancer remain a challenge.

Methods: We performed an integrative multi-platform analysis of a cervical cancer cohort from The Cancer Genome Atlas (TCGA) based on 284 clinical cases and identified the driver genes and possible molecular classification of cervical cancer.

Results: Multi-platform integration showed that cervical cancer exhibited a wide range of mutation. The top 10 mutated genes were TTN, PIK3CA, MUC4, KMT2C, MUC16, KMT2D, SYNE1, FLG, DST, and EP300, with a mutation rate from 12 to 33%. Applying GISTIC to detect copy number variation (CNV), the most frequent chromosome arm-level CNVs included losses in 4p, 11p, and 11q and gains in 20q, 3q, and 1q. Then, we performed unsupervised consensus clustering of tumor CNV profiles and methylation profiles and detected four statistically significant expression subtypes. Finally, by combining the multidimensional datasets, we identified 10 potential driver genes, including GPR107, CHRNA5, ZBTB20, Rb1, NCAPH2, SCA1, SLC25A5, RBPMS, DDX3X, and H2BFM.

Conclusions: This comprehensive analysis described the genetic characteristic of cervical cancer and identified novel driver genes in cervical cancer. These results provide insight into developing precision treatment in cervical cancer.

Circulating miR-15b, miR-34a and miR-218 as promising novel early low-invasive biomarkers of cervical carcinogenesis

Circulating biological markers, such as miRNAs, hold the greatest possibilities to complement tissue biopsy and clinical diagnostic tests. The objective of this study was to evaluate the relative abundance of three circulating miRNAs in serum from 17 HPV16-positive patients with early cervical lesions known as Low-Grade Squamous Intraepithelial Lesions (LSILs). The expression of circulating microRNAs miR-15b, miR-34a and miR-218 in patients with LSILs was compared to 23 HPV-negative individuals showing normal cervical epithelium (healthy women) and 23 Squamous Cell Carcinoma (SCC) samples. The expression levels of miR-15b remained unchanged while those of miRNAs 34a and 218 were relatively high in serum obtained from LSIL patients in comparison with healthy women (results were statistically significant with a p of < 0.01 or < 0.001). According to previous findings, miR-15b was overexpressed and miRNAs 34a and 218 were underexpressed in serum from SCC patients. Additionally, the mRNA expression levels of some selected gene targets were determined [Cyclin D1 (CCND1), Cyclin E1 (CCNE1), B-cell lymphoma 2 (Bcl-2) and MutS homolog 2 (MSH-2)]. All serum results correlated with tissue samples from the same patients. We propose that circulating microRNAs can be valuable as molecular markers for the early follow-up of cervical carcinogenesis risk.

The relationship between the PD-1/PD-L1 pathway and DNA mismatch repair in cervical cancer and its clinical significance

Background

According to recent clinical observations, deficient DNA mismatch repair (dMMR) is capable of improving antitumor effects of the PD-1/PD-L1 pathway, suggesting that dMMR may act as a prognostic indicator of PD-1/PD-L1 antibody drugs. In this study, we examined the dMMR and PD-1/PD-L1 expression, as well as explored the correlation of dMMR status with PD-1/PD-L1 expression in cervical cancer patients, in order to optimize cervical cancer patient selection for PD-1/PD-L1 antibody drug treatment, which is helpful to avoid adverse effects and keep costs manageable.

Methods

Sixty-six tissue samples from patients with squamous cell carcinoma were collected, and data of their clinical characteristics were also gathered. Based on these samples, the expression levels of MLH1, MSH2, and PD-L1 in cancer cells were tested by immunohistochemical assay (IHC). Moreover, PD-1/PD-L1 expression in tumor-invading lymphocytes (TILs) was detected by IHC as well. Six single-nucleotide-repeat markers of microsatellite instability (MSI), including NR-27, MONO-27, BAT-25, NR-24, NR-21, and BAT-26, were tested by capillary electrophoresis sequencer analysis. According to expression of MLH1, MSH2 and the MSI test, all 66 cases were divided into dMMR or proficient DNA mismatch repair (pMMR) groups. The comparisons of dMMR and PD-L1 in cancer cells and of PD-1/PD-L1 in TILs were conducted categorized by age, childbearing history, history of abortion, ethnicity, and cancer cell differentiation subgroup. Furthermore, PD-L1 levels in cancer cells and PD-1/PD-L1 in TILs were analyzed and compared in both dMMR and pMMR subgroups.

Results

Of the patient samples, 25.8% were associated with dMMR. PD-L1 in cancer cells, PD-L1 in TILs, and PD-1 in TILs took up 59.1%, 47.0%, and 60.6%, respectively. The data indicated that both dMMR and PD-L1 overexpression resulted from lower cancer differentiation, more incidences of childbearing, and a history of abortion. Abortion could significantly increase PD-1 expression levels in TILs. Additionally, more incidence of childbearing or older age (35–55 years) was able to upregulate PD-L1 expression in TILs. Statistical difference of PD-L1 in cancer cells could be observed between dMMR and pMMR subgroups. In the dMMR group, PD-L1 in cancer cells and PD-1 in TILs had no correlation (r_s=0.161, p=0.537), but in the pMMR group, they had good correlation (r_s=0.645, p<0.001).

Conclusion

According to prior studies and our own experiments, PD-L1 in both cancer cells and TILs and PD-1 in TILs are widely observed in cervical cancer patients, indicating that there may be potential to apply PD-1/PD-L1 antibody drugs in cervical cancer. dMMR patients are associated with higher PD-L1 expression compared with pMMR ones, which suggested that PD-1/PD-L1 antibody drugs may work well in dMMR cervical cancer patients. Moreover, in patients with more incidences of childbearing or abortion, dMMR may be a molecular detection target for clinical application of PD-1/PD-L1 antibody drugs.

Multiple-integrations of HPV16 genome and altered transcription of viral oncogenes and cellular genes are associated with the development of cervical cancer

The constitutive expression of the high-risk HPV E6 and E7 viral oncogenes is the major cause of cervical cancer. To comprehensively explore the composition of HPV16 early transcripts and their genomic annotation, cervical squamous epithelial tissues from 40 HPV16-infected patients were collected for analysis of papillomavirus oncogene transcripts (APOT). We observed different transcription patterns of HPV16 oncogenes in progression of cervical lesions to cervical cancer and identified one novel transcript. Multiple-integration events in the tissues of cervical carcinoma (CxCa) are significantly more often than those of low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL). Moreover, most cellular genes within or near these integration sites are cancer-associated genes. Taken together, this study suggests that the multiple-integrations of HPV genome during persistent viral infection, which thereby alters the expression patterns of viral oncogenes and integration-related cellular genes, play a crucial role in progression of cervical lesions to cervix cancer.

Low expression of MSH2 DNA repair protein is associated with poor prognosis in head and neck squamous cell carcinoma

Objective

This study aimed to investigate the expression of the MSH2 DNA repair protein in head and neck squamous cell carcinoma (HNSCC) in order to analyze its association with clinicopathologic factors and overall survival of patients.

Material and Methods

Clinical data and primary lesions of HNSSC were collected from 55 patients who underwent surgical resection with postoperative radiotherapy in Montes Claros, state of Minas Gerais, Brazil, between 2000 and 2008. Immunohistochemical reactions were performed to analyze MSH2 protein expression.

Results

Bivariate analysis showed no significant correlation or association between MSH2 expression and clinicopathologic parameters by Mann-Whitney and Kruskal-Wallis tests. Patients with locoregional metastatic disease (OR=4.949, p<0.001) and lower MSH2 immunohistochemical expressions (OR=2.943, p=0.032) presented poorer survival for HNSCC by Cox regression models.

Conclusions

Our data demonstrated that lower MSH2 expression might contribute to a higher clinic aggressiveness of HNSCC by promoting an unfavorable outcome.

Stabilization of mismatch repair gene PMS2 by glycogen synthase kinase 3beta is implicated in the treatment of cervical carcinoma

Background

PMS2 expression loss was reported in a variety of human. However, its importance has not been fully understood in cervical carcinoma. The aim of this study was to determine the expression of PMS2 in cervical carcinoma and evaluate the significance of mismatch repair gene PMS2 regulated by glycogen synthase kinase 3β (GSK-3β) in chemosensitivity.

Methods

We examined PMS2 and phosphorylated GSK-3β(s9) expression in cervical carcinoma tissues using immunohistochemical staining. Furthermore, we detected PMS2 expression in HeLa cells and evaluate the interaction with GSK-3β after transfection with GSK-3β by small interference RNA (siRNA), co-immunoprecipitation and immunoblotting. We also evaluated the effect of PMS2 transfection on HeLa cells' chemosensitivity to cisplatin treatment.

Results

We found significant downregulation of PMS2 in cervical carcinoma, which was negatively associated with phosphorylated GSK-3β (s9). Furthermore, we demonstrated GSK-3β transfection was able to interact with PMS2 and enhance PMS2 production in HeLa cells, and increased PMS2 production was responsible for enhanced chemosensitivity.

Conclusions

Our results provide the evidence that stabilization of PMS2 production by GSK-3β was important to improve chemosensitization, indicating the significance of GSK-3β-related PMS2 downregulation in the development of cervical carcinoma and in developing a potential strategy for chemotherapy.

DNA mismatch repair and the transition to hormone independence in breast and prostate cancer

The molecular basis for the progression of breast and prostate cancer from hormone dependent to hormone independent disease remains a critical issue in the management of these two cancers. The DNA mismatch repair system is integral to the maintenance of genomic stability and suppression of tumorigenesis. No firm consensus exists regarding the implications of mismatch repair (MMR) deficiencies in the development of breast or prostate cancer. However, recent studies have reported an association between mismatch repair deficiency and loss of specific hormone receptors, inferring a potential role for mismatch repair deficiency in this transition. An updated review of the experimental data supporting or contradicting the involvement of MMR defects in the development and progression of breast and prostate cancer will be provided with particular emphasis on their implications in the transition to hormone independence.