Expression of phosphorylated histone H2AX (γ-H2AX) in normal and neoplastic squamous epithelia of the uterine cervix: an immunohistochemical study with epidermal growth factor receptor

Coordinated dysregulation of cancer progression by the HER family and p21-activated kinases

Most epithelial cancer types are polygenic in nature and are driven by coordinated dysregulation of multiple regulatory pathways, genes, and protein modifications. The process of coordinated regulation of cancer promoting pathways in response to extrinsic and intrinsic signals facilitates the dysregulation of several pathways with complementary functions, contributing to the hallmarks of cancer. Dysregulation and hyperactivation of cell surface human epidermal growth factor receptors (HERs) and cytoskeleton remodeling by p21-activated kinases (PAKs) are two prominent interconnected aspects of oncogenesis. We briefly discuss the discoveries and significant advances in the area of coordinated regulation of HERs and PAKs in the development and progression of breast and other epithelial cancers. We also discuss how initial studies involving heregulin signaling via HER3-HER2 axis and HER2-overexpressing breast cancer cells not only discovered a mechanistic role of PAK1 in breast cancer pathobiology but also acted as a bridge in generating a broader cancer research interest in other PAK family members and cancer types and catalyzed establishing the role of PAKs in human cancer, at-large. In addition, growth factor stimulation of the PAK pathway also helped to recognize new facets of PAKs, connecting the PAK pathway to oncogenesis, nuclear signaling, gene expression, mitotic progression, DNA damage response, among other phenotypic responses, and shaped the field of PAK cancer research. Finally, we recount some of the current limitations of HER- and PAK-directed therapeutics in counteracting acquired therapeutic resistance and discuss how cancer's as a polygenic disease may be best targeted with a polygenic approach.

gamma-H2AX: Can it be established as a classical cancer prognostic factor?

Double-strand breaks are among the first procedures taking place in cancer formation and progression as a result of endogenic and exogenic factors. The histone variant H2AX undergoes phosphorylation at serine 139 due to double-strand breaks, and the gamma-H2AX is formatted as a result of genomic instability. The detection of gamma-H2AX can potentially serve as a biomarker for transformation of normal tissue to premalignant and consequently to malignant tissues. gamma-H2AX has already been investigated in a variety of cancer types, including breast, lung, colon, cervix, and ovary cancers. The prognostic value of gamma-H2AX is indicated in certain cancer types, such as breast or endometrial cancer, but further investigation is needed to establish gamma-H2AX as a prognostic marker. This review outlines the role of gamma-H2AX in cell cycle, and its formation as a result of DNA damage. We investigate the role of gamma-H2AX formation in several cancer types and its correlation with other prognostic factors, and we try to find out whether it fulfills the requirements for its establishment as a classical cancer prognostic factor.

PAKs in Human Cancer Progression: From Inception to Cancer Therapeutic to Future Oncobiology

Since the initial recognition of a mechanistic role of p21-activated kinase 1 (PAK1) in breast cancer invasion, PAK1 has emerged as one of the widely overexpressed or hyperactivated kinases in human cancer at-large, allowing the PAK family to make in-roads in cancer biology, tumorigenesis, and cancer therapeutics. Much of our current understanding of the PAK family in cancer progression relates to a central role of the PAK family in the integration of cancer-promoting signals from cell membrane receptors as well as function as a key nexus-modifier of complex, cytoplasmic signaling network. Another core aspect of PAK signaling that highlights its importance in cancer progression is through PAK's central role in the cross talk with signaling and interacting proteins, as well as PAK's position as a key player in the phosphorylation of effector substrates to engage downstream components that ultimately leads to the development cancerous phenotypes. Here we provide a comprehensive review of the recent advances in PAK cancer research and its downstream substrates in the context of invasion, nuclear signaling and localization, gene expression, and DNA damage response. We discuss how a deeper understanding of PAK1's pathobiology over the years has widened research interest to the PAK family and human cancer, and positioning the PAK family as a promising cancer therapeutic target either alone or in combination with other therapies. With many landmark findings and leaps in the progress of PAK cancer research since the infancy of this field nearly 20 years ago, we also discuss postulated advances in the coming decade as the PAK family continues to shape the future of oncobiology.

Dysregulation of PAK1 Is Associated with DNA Damage and Is of Prognostic Importance in Primary Esophageal Small Cell Carcinoma

Primary esophageal small cell carcinoma (PESCC) is a rare, but fatal subtype of esophageal carcinoma. No effective therapeutic regimen for it. P21-activated kinase 1 (PAK1) is known to function as an integrator and an indispensable node of major growth factor signaling and the molecular therapy targeting PAK1 has been clinical in pipeline. We thus set to examine the expression and clinical impact of PAK1 in PESCC. The expression of PAK1 was detected in a semi-quantitative manner by performing immunohistochemistry. PAK1 was overexpressed in 22 of 34 PESCC tumors, but in only 2 of 18 adjacent non-cancerous tissues. Overexpression of PAK1 was significantly associated with tumor location (p = 0.011), lymph node metastasis (p = 0.026) and patient survival (p = 0.032). We also investigated the association of PAK1 with DNA damage, a driven cause for malignancy progression. γH2AX, a DNA damage marker, was detectable in 18 of 24 (75.0%) cases, and PAK1 expression was associated with γH2AX (p = 0.027). Together, PAK1 is important in metastasis and progression of PESCC. The contribution of PAK1 to clinical outcomes may be involved in its regulating DNA damage pathway. Further studies are worth determining the potentials of PAK1 as prognostic indicator and therapeutic target for PESCC.

Expression of the γ-phosphorylated histone H2AX in gastric carcinoma and gastric precancerous lesions

The histone γH2AX is a marker of activated DNA damage that is overexpressed in various cancers and corresponding precursor lesions, indicating that γH2AX is a component in oncogenic transformation. The present study aimed to determine whether the immunohistochemical expression of γH2AX is involved in the progression between superficial gastritis (n=20), atrophic gastritis (n=24) and gastric carcinoma (n=79). There was no increase in γH2AX expression between superficial and atrophic gastritis, but there was a significant increase in γH2AX expression between these two conditions and gastric carcinoma (χ²=68.712; P<0.001). The expression of γH2AX in moderately-differentiated gastric adenocarcinoma (n=49) was evidently higher compared with poorly-differentiated gastric adenocarcinoma (n=26; χ²=14.241; P<0.01). Staining for γH2AX did not reveal a significant association between the expression of the histone and patient age, depth of invasion, lymph node metastasis or the tumor-node-metastasis stage of the gastric carcinoma. Overall, the present study demonstrated that enhanced γH2AX expression may be closely associated with gastric carcinoma, but is less likely to be involved in the genesis of gastric carcinoma.

Genetic variations in EGFR and ERBB4 increase susceptibility to cervical cancer

OBJECTIVES

Inherited genetic variability contributes to susceptibility to cervical cancer. We investigated the association of single nucleotide polymorphisms (SNPs) in the human epidermal growth factor receptor (ERBB) family with cervical cancer.

METHODS

We used the transmission disequilibrium test (TDT) to look for excessive transmission of tag single nucleotide polymorphisms (tSNPs) in ERBB family members EGFR, ERBB2, ERBB3, and ERBB4 in a large sample of women with invasive and in situ cervical cancer and their biological parents (628 trios). The study used a discovery set of trios (244) analyzed by Illumina GoldenGate in which SNPs reaching a P<.05 were re-tested by TaqMan in the combined set of 628. We also explored collaborative effects of different ERBB alleles.

RESULTS

Based on single SNP TDT tests we identified 16 significant SNPs in the discover stage and six of 14 SNPs that could be assayed by TaqMan were significantly overtransmitted in women with cervical cancer in the combined replication set. Four SNPs were located in intron 1 of EGFR and two SNPs in intron 24 of ERBB4. The EGFR variants are located near multiple enhancers, silencers, and the previously identified functional common polymorphisms in intron 1.

CONCLUSIONS

Our data provide evidence for the involvement of intron 1 EGFR variants and intron 24 ERBB4 variants in modulating risk for the development of in situ and invasive cervical cancer. These variants should be examined in additional populations and functional studies would be needed to confirm this hypothesis.

Loss of E-cadherin and Acquisition of Vimentin in Epithelial-Mesenchymal Transition are Noble Indicators of Uterine Cervix Cancer Progression

BACKGROUND

Epithelial-mesenchymal transition (EMT) has been known to play a key role in the stromal invasion of carcinoma in situ (CIS) lesion. Loss of E-cadherin and acquisition of vimentin are two critical steps in EMT, that are induced by Snail-1 upregulation associated with overexpression of epidermal growth factor receptor (EGFR). However, roles of EMT-related proteins in human cervical tissues have not been fully elucidated. In this study, we investigated the immunoexpressions of EMT-related proteins in CIS, microinvasive squamous cell carcinoma (SCC), and invasive SCC to demonstrate their key roles in tumor progression.

METHODS

Eighty one CIS, 17 microinvasive, and 21 invasive SCC cases were immunostained with primary antibodies for Snail-1, EGFR, E-cadherin, and vimentin on paraffin-embedded tissue microarray blocks.

RESULTS

EGFR and Snail-1 proteins were highly expressed but the levels were not significantly different between the three groups. However, loss of E-cadherin and acquisition of vimentin were proven to occur significantly higher in microinvasive and invasive SCC cases than in CIS.

CONCLUSIONS

E-cadherin and vimentin were found to be two useful indicators of EMT in evaluating stromal invasion of CIS. However, it was not demonstrated for Snail-1 and EGFR proteins to play any key role in the progression of cervix cancer.

γ-H2AX and other histone post-translational modifications in the clinic

Chromatin is a dynamic complex of DNA and proteins that regulates the flow of information from genome to end product. The efficient recognition and faithful repair of DNA damage, particularly double-strand damage, is essential for genomic stability and cellular homeostasis. Imperfect repair of DNA double-strand breaks (DSBs) can lead to oncogenesis. The efficient repair of DSBs relies in part on the rapid formation of foci of phosphorylated histone H2AX (γ-H2AX) at each break site, and the subsequent recruitment of repair factors. These foci can be visualized with appropriate antibodies, enabling low levels of DSB damage to be measured in samples obtained from patients. Such measurements are proving useful to optimize treatments involving ionizing radiation, to assay in vivo the efficiency of various drugs to induce DNA damage, and to help diagnose patients with a variety of syndromes involving elevated levels of γ-H2AX. We will survey the state of the art of utilizing γ-H2AX in clinical settings. We will also discuss possibilities with other histone post-translational modifications. The ability to measure in vivo the responses of individual patients to particular drugs and/or radiation may help optimize treatments and improve patient care. This article is part of a Special Issue entitled: Chromatin in time and space.

immunohistochemical expression of survivin and γ-H2AX in vulvar intraepithelial neoplasia and low-stage squamous cell carcinoma

Survivin inhibits apoptosis and is involved in the regulation of cell cycle progression and in the mitotic spindle formation. It is overexpressed in many cancers. The histone γ-H2AX is a marker of activated DNA damage and is overexpressed in different cancers and their precursor lesions. It also forms early during apoptosis. Eighty-seven formalin-fixed, paraffin-embedded archival vulvar tissues originating from 55 preoperatively untreated patients were immunostained with antibodies to survivin and γ-H2AX to determine their expression in normal squamous vulvar epithelia (NE, n=25), lichen sclerosus (n=10), high-grade classic vulvar intraepithelial neoplasia (n=16), differentiated vulvar intraepithelial neoplasia (n=16), and vulvar invasive keratinizing squamous cell carcinoma (ISCC, n=20; FIGO Ib). Immunostaining for both factors was scored for moderate and strong intensities with regard to quantity. Statistical analysis was performed by the χ test and Fisher exact test. Nuclear surviving expression increased from NE and lichen scleros to high-grade classic vulvar intraepithelial neoplasia, differentiated vulvar intraepithelial neoplasia, and ISCC significantly (P=0.0001) and followed the distribution of immature squamous epithelial cells. Positive scores for γ-H2AX were found in nuclei of cells in all diagnostic cohorts, in any epithelial level with some accentuation in the upper layers, was seen in pycnotic nuclei in horn pearls of ISCC and apoptotic bodies, without relevant statistical distributions. Immunoscores did not differ between grade 1 and grades 2/3. Expression patterns were different for both factors, suggesting their involvement in different biologic mechanisms as an early event leading to resistance to apoptosis in vulvar carcinogenesis.