Induction of HRR genes and inhibition of DNMT1 is associated with anthracycline anti-tumor antibiotic-tolerant breast carcinoma cells

Differential association of hedgehog pathway in development of cervical carcinoma and its chemo-tolerance

Cervical carcinoma (CACX) is still a dreadful threat to women in developing countries. Available conventional chemo-radiation therapies are not sufficient to restrict the disease recurrence. To unravel the mechanism of the disease recurrence, alteration of hedgehog self-renewal pathway was evaluated during development of CACX and in chemo-tolerance of the tumor. We have analyzed the alterations (expression/methylation/deletion) of some key regulatory genes (HHIP/SUFU/SHH/ SMO/GLI1) of hedgehog self-renewal pathway in cervical lesions at different clinical stages and compared with different datasets, followed by their clinico-pathological correlations. The changes in expression/methylation of the genes were then evaluated in two CACX cell lines (SiHa/HeLa) after treatment with chemotherapeutic drug cisplatin at different concentrations. Down regulation (mRNA/protein) of the antagonists HHIP and SUFU due to promoter methylation and/or deletion along with upregulation (protein) of agonists SHH, SMO and GLI1 was seen in early invasive lesions and subsequent clinical stages. Reduced protein expression of HHIP and SUFU showed significant association with high/intermediate expression of agonists SHH, SMO, GLI1 in the tumors and also poor prognosis of the patients. It was evident that cisplatin could restrict the growth of HeLa and SiHa cells through significant upregulation of antagonists HHIP and SUFU due to their promoter hypomethylation and down regulation of SHH in a concentration dependent manner without any significant changes in expression of SMO and GLI1, leading to the tumor cells in a dormant state. Thus, interplay of the agonists and antagonists has important role in activation of hedgehog pathway during development of CACX, whereas inactivation of the pathway due to upregulation of the antagonists is an important phenomenon in chemo-tolerance of the tumor. This suggests importance of epigenetic modification in chemo-resistance of CACX.

High nuclear expression of DNMT1 in correlation with inactivation of TET1 portray worst prognosis among the cervical carcinoma patients: clinical implications

In this study, we aimed to understand the interplay of the epigenetic modifier genes DNMT1 and TET1 along with HPV infection in the cervical epithelium and how it changes during tumorigenesis. For this purpose, initially the bioinformatical analysis (methylation and expression profile) of DNMT1 and TET1 was analyzed in the TCGA dataset. Next genetic (deletion) and epigenetic profiling (promoter methylation) of DNMT1 and TET1 were done in our sample pool and also validated in CACX cell lines as well. The results were further correlated with different clinicopathological parameters. Our data revealed that HPV infection in basal/parabasal layers of cervical epithelium actually disrupts the epigenetic homeostasis of DNMT1 and TET1 proteins which ultimately leads to the high expression of DNMT1 along with further reduction in TET1 protein during the development of carcinoma. Further, in-depth look into the results revealed that comparatively low methylation frequency of DNMT1 coupled with high promoter methylation and deletion frequency [22-46%] of TET1 were the plausible reasons of their antagonistic expression profile during the progression of the disease. Interestingly, the prevalence of DNMT1 [9.1%] and TET1 promoter methylation [22.7%] found in both the plasma DNA of the respective CACX patients implicated its diagnostic importance in this study. Lastly, molecular alteration of TET1 alone or in combination with DNMT1 showed the worst overall survival among the patients. Hence, it may be concluded that an inverse molecular profile of DNMT1 and TET1 genes seen in the proliferative basal-parabasal layers of the cervical epithelium was aggravated during the development of CACX along with genetic and epigenetic changes due to HPV infection.

Downregulation of Hyaluronic acid-CD44 signaling pathway in cervical cancer cell by natural polyphenols Plumbagin, Pongapin and Karanjin

Hyaluronic acid (HA)-CD44 pathway showed association with several malignancies. The natural polyphenols Plumbagin, Pongapin and Karanjin showed anti-cancer activities in different tumors including cervical carcinoma. To understand their mechanism of anti-cancer activity, the effect of the compounds on HA-CD44 pathway was analyzed in cervical cancer cell line HeLa. The mRNA expression of three different isoforms of CD44 i.e., CD44s, CD44v3, and CD44v6, was differentially downregulated by the compounds. This was validated by Western blot and immunocytochemical analysis of CD44s.The low molecular weight HA (LMW-HA) showed growth promoting activity in HeLa at low concentration, whereas high molecular weight HA (HMW-HA) had no such effect. The compounds could preferentially downregulate the LMW-HA level in HeLa, as evident in the cell as well as in the cell-free conditioned medium. Concentration-dependent upregulation of HA synthase-2 (HAS2) was seen in the cell by the compounds, whereas differential downregulation of hyalurinidases 1-4 (HYAL 1-4), predominantly HYAL1, were seen. The compounds could also downregulate the downstream target of the pathway p-AKT (T-308) in concentration-dependent manner. Thus, the compounds could attenuate the HA-CD44 pathway in HeLa cell to restrict the tumor growth.

High nuclear expression of HIF1α, synergizing with inactivation of LIMD1 and VHL, portray worst prognosis among the bladder cancer patients: association with arsenic prevalence

PURPOSE

Our study was aimed to understand the importance of LIMD1-VHL-HIF1α pathway in development of bladder carcinoma (BlCa) in association with arsenic prevalence.

METHODS

At first, the mRNA expression pattern of the genes of this pathway (LIMD1, VHL and HIF1α) was checked in GEO datasets and in our samples. Next, genetic and epigenetic profiling of LIMD1 and VHL was done in our sample pool, validated in T24 BlCa cell line. The results were next correlated with various clinico-pathological parameters.

RESULTS

Differential under-expression of LIMD1 and VHL genes was found in muscle-invasive BlCa (MIBC) in comparison to non-muscle-invasive BlCa (NMIBC). However, HIF1α protein, but mRNA, was found to be overexpressed among the MIBC samples; depicting the probability of HIF1α protein stabilization. Analysis of genetic and epigenetic profiles of LIMD1 and VHL exposed a frequent promoter methylation of LIMD1 gene in MIBC samples. Further, in-depth look into the results unveiled that the high nuclear expression of HIF1α was significantly correlated with genetic alterations of LIMD1, alone or in combination with VHL. Moreover, treating the T24 cells with a de-methylating agent (5-aza-2'-deoxycytidine) re-expressed the methylated LIMD1 and VHL genes, which in turn, reduced the HIF1α protein level significantly. Additionally, patients with high arsenic content (> 112 ng/g, AsH) seemed to have recurrent promoter methylation in LIMD1, as well as co-methylation/alteration of LIMD1 and VHL gene. Lastly, high nuclear expression of HIF1α in association with co-alteration of VHL and LIMD1 showed the worst overall survival (OS) among the patients.

CONCLUSION

To conclude, MIBC samples portrayed higher alterations in VHL and LIMD1, thereby, stabilizing HIF1α protein and lowering the OS of patients.

Divergent molecular profile of PIK3CA gene in arsenic-associated bladder carcinoma

The activation of PIK3CA in bladder carcinoma (BlCa) with its recurrent mutations in exon 9 and 20 were well reported. But the association of arsenic on the activation of the pathway is not well elucidated. Therefore, we aimed to analyse the effect of arsenic on the genetic (copy number variation/mutation) and expression profiles of PIK3CA in primary BlCa samples. Infrequent amplification (16%) of the PIK3CA locus was observed, with higher frequency among the arsenic-high (AsH) than arsenic-low (AsL) samples. Frequent (54%) tumour-specific mutations in exon 9 and 20 of PIK3CA were observed in the BlCa samples with prevalent (47%) C>T transition mutations. Exon 9 and 20 harboured 48% and 73% of the total mutations, respectively, with 37% in E542K/E545K and 25% of the mutation in H1047Y/R. Though mutation frequency in AsH and AsL was found to be comparable, we observed some arsenic-specific mutation at c.1633G>A, c.1634A>C (E545K) and c.2985C>T and c.3130G>T mutations, as well as prevalent transverse mutations of A>C and G>T in AsH group. Furthermore, 73% of the BlCa samples showed overexpression (mRNA/protein) of PIK3CA with genetic alterations (amplification/mutation), significantly (P = 0.01) higher in AsH group. However, 36% of the samples showed overexpressed PIK3CA, independent of mutation or amplification, signifying a transcriptional upregulation of PIK3CA gene. Therefore, the expression status of NFκB, a transcription factor of PIK3CA, was assessed and found to be significantly correlated with the overexpression of PIK3CA (mRNA/protein) in AsH group. Similarly, the expression pattern of pAKT1 (Thr 308) was also found to be significantly correlated with PIK3CA overexpression. Finally, AsH patients with the overexpression of PIK3CA or NFκB had the worst overall survival, signifying a strong impact of arsenic on this pathway and outcome of the patients. Thus, our study showed that the arsenic-associated differential molecular profile of PIK3CA/AKT1/NFkB in BlCa has an important role in the molecular pathogenesis of the disease.

Downregulation of beta-catenin in chemo-tolerant TNBC through changes in receptor and antagonist profiles of the WNT pathway: Clinical and prognostic implications

PURPOSE

In approximately 30% of triple-negative breast cancer (TNBC) patients a complete pathological response is achieved. However, after neo-adjuvant chemotherapy treatment (NACT) residual tumour cells can be intrinsically resistant to chemotherapy. In this study, associations of the WNT/beta-catenin pathway with chemo-tolerance of NACT treated TNBC patients were compared to that of pre-treatment TNBC patients.

METHODS

Expression analyses were performed in both pre-treatment and NACT treated TNBC samples using immunohistochemistry and qRT-PCR, along with DNA copy number variation (CNV) and promoter methylation analyses to elucidate the mechanism(s) underlying chemo-tolerance. In addition, in vitro validation experiments were performed in TNBC cells followed by in vivo clinicopathological correlation analyses.

RESULTS

A reduced expression (41.1%) of nuclear beta-catenin together with a low proliferation index was observed in NACT samples, whereas a high expression (59.0%) was observed in pre-treatment samples. The reduced nuclear expression of beta-catenin in the NACT samples showed concordance with reduced expression levels (47-52.9%) of its associated receptors (FZD7 and LRP6) and increased expression levels (35.2-41.1%) of its antagonists (SFRP1, SFRP2, DKK1) compared to those in the pre-treatment samples. The expression levels of the receptors showed no concordance with its respective gene copy number/mRNA expression statuses, regardless treatment. Interestingly, however, significant increases in promoter hypomethylation of the antagonists were observed in the NACT samples compared to the pre-treatment samples. Similar expression patterns of the antagonists, receptors and beta-catenin were observed in the TNBC-derived cell line MDA-MB-231 using the anthracyclines doxorubicin and nogalamycin, suggesting the importance of promoter hypomethylation in chemotolerance. NACT patients showing reduced receptor and/or beta-catenin expression levels and high antagonist expression levels exhibited a comparatively better prognosis than the pre-treatment patients.

CONCLUSIONS

Our data suggest that reduced nuclear expression of beta-catenin in NACT TNBC samples, due to downregulation of its receptors and upregulation of its antagonists through promoter hypomethylation of the WNT pathway, plays an important role in chemo-tolerance.

Reduction of nuclear Y654-p-β-catenin expression through SH3GL2-meditated downregulation of EGFR in chemotolerance TNBC: Clinical and prognostic importance

Triple negative breast cancer (TNBC) originates from a less differentiated ductal cell of breast, which is less sensitive to chemotherapy. The chemotolerance mechanism of TNBC has not yet been studied in detail. For this reason, molecular profiles (expression/genetic/epigenetic) of Y654-p-β-catenin (active) and its kinase epidermal growth factor receptor (EGFR) along with SH3GL2 (regulator of EGFR homeostasis) were compared between neoadjuvant chemotherapy treated (NACT) and pretherapeutic TNBC samples. Reduced nuclear expression of Y654-p-β-catenin protein with low proliferation index and CD44 prevalence showed concordance with reduced expression of EGFR/Y1045-p-EGFR proteins in the NACT samples than the pretherapeutic TNBC samples. Infrequent messenger RNA expression, gene amplification (10-32.5%), and mutation (1%) of EGFR were seen in the TNBC samples irrespective of therapy, suggesting the importance of EGFR protein stabilization in this tumor. The upregulation of SH3GL2 seen in the NACT samples in contrast to the pretherapeutic samples might be due to its promoter hypomethylation, as seen in the quantitative methylation assay. A similar trend of upregulation of SH3GL2 and downregulation of EGFR, Y1045-p-EGFR, Y654-p-β-catenin were seen in the MDA-MB-231 cell line using antharacycline antitumor drugs (doxorubicin/nogalamycin). The NACT patients with reduced expression of Y654-p-β-catenin and/or EGFR and high expression of SH3GL2 showed comparatively better prognosis than the pretherapeutic patients. Thus, our study showed that reduced nuclear expression of Y654-p-β-catenin in NACT samples due to downregulation of EGFR protein through promoter hypomethylation-mediated upregulation of SH3GL2, resulting in low proliferation index/CD44 prevalence with better prognosis of the NACT patients, might have an important role in the chemotolerance of TNBC.

Hypomethylation of mismatch repair genes MLH1 and MSH2 is associated with chemotolerance of breast carcinoma: Clinical significance

BACKGROUND AND OBJECTIVES

The aim of the study was to understand the importance of mismatch repair genes MLH1 and MSH2 in chemotolerance and prognosis of breast carcinoma (BC).

METHODS

First, the alterations (deletion/methylation/expression) of MLH1 and MSH2 were analyzed in 45 neoadjuvant chemotherapy (NACT)-treated and 133 pretherapeutic BC samples. The chemotolerant BC cells were characterized by treating two BC cell lines MCF-7 and MDA MB 231 with two anthracycline antitumor antibiotics, doxorubicin and nogalamycin.

RESULTS

The deletion frequencies were 32% to 38% in MLH1/MSH2 genes and promoter methylation frequencies were 49% to 62% in MLH1 and 41% to 51% in MSH2 in both NACT-treated and pretherapeutic samples. The overall alteration of MLH1 and MSH2 was 58% to 71% in the samples. Reduced messenger RNA (mRNA) and protein expression were found in both the genes and it showed concordance with the molecular alterations. NACT-treated patients showed better prognosis. The chemotherapeutic drug induced increased mRNA/protein expression of the genes in BC cell lines was due to their promoter hypomethylation, as analyzed by quantitative methylation assay. This phenomenon was also evident in NACT-treated BC samples.

CONCLUSION

MLH1/MSH2 genes play a critical role in the development of BC. Hypomethylation of MLH1/MSH2 genes might be important in chemotolerance of the disease.