Hirochika Matsubara

Critical and Diverse Involvement of Akt/Mammalian Target of Rapamycin Signaling in Human Lung Carcinomas

BACKGROUND: Aberrant signaling cascades emanating from epidermal growth factor receptor (EGFR) are involved in the complex network of oncogenic signaling in lung carcinomas. One representative cascade is the phosphatidylinositol 3‐kinase/Akt/mammalian target of rapamycin (mTOR) pathway. METHODS: The authors investigated the involvement of mTOR in the pathobiologic profiles of 150 specimens of lung carcinoma by immunohistochemistry and immunoblotting in correlation with the upstream and downstream proteins Akt and p70S6‐kinase (S6K), respectively. RESULTS: Immunohistochemistry revealed Akt activation in 44% of tumors and mTOR expression in 68.7% of tumors, and the preponderance of activation was observed in adenocarcinoma (AC) (100%). Phosphorylated mTOR (p‐mTOR) was observed in 53.3% of tumors and had the highest frequency in AC (89.7%). In AC, the frequency of p‐mTOR staining was higher in the well differentiated subtype, in particular, in the acinar structure. However, little correlation was observed between the activation of mTOR and Akt, except in the 5 AC specimens that harbored an EGFR gene mutation, which exhibited constitutive activation of both Akt and mTOR. Conversely, in squamous cell carcinomas, mTOR activation was associated with a significantly higher frequency of lymph node metastasis. CONCLUSIONS: The results of this study suggested the dual functions of mTOR. First, mTOR may function not only in the proliferation of tumor cells as an effector molecule downstream of EGFR but also possibly in the morphogenesis of AC. Second, the activation of mTOR may play a key role in metastasis in squamous cell carcinoma. Overall, the current results demonstrated the potential for the application of rapamycin, an mTOR inhibitor, as an additional novel component of chemotherapy for a defined subset of patients with lung carcinoma. Cancer 2009.

Paradigm of kinase-driven pathway downstream of epidermal growth factor receptor/Akt in human lung carcinomas ☆ ☆☆

The expression/activation of epidermal growth factor receptor (EGFR) and the correlation with the phosphorylation status of downstream modulator proteins, Akt, mammalian target of rapamycin (mTOR), p70S6-kinase (S6K), ribosomal protein S6 (rS6), and eukaryotic initiation factor 4E-binding protein 1 (4E-BP1), were analyzed and EGFR/Akt signaling was evaluated in lung carcinomas. Immunohistochemical analysis of 140 cases revealed overexpression of EGFR in 37.9% and phosphorylation in 37.1%, but much less in small cell carcinoma. Combined analysis with immunoblotting revealed that when EGFR is activated, at least one of the mTOR/S6K or mTOR/4E-BP1 cascades was activated in 60% of the cases. Furthermore, constitutive activation of EGFR-Akt-mTOR was found in 17.9% of nonsmall cell lung carcinomas (NSCLCs). For each protein, the frequencies of the activation vary among histologic types. In adenocarcinoma (AC), 90% revealed mTOR activation regardless of EGFR status, and 60% of these showed activation of downstream S6K/rS6. Furthermore, mutation of EGFR was frequently accompanied by phosphorylation of EGFR and constitutive activation of entire EGFR through rS6 was observed in 50% of carcinoma harboring EGFR mutation, including squamous cell carcinoma (SCC). By clinicopathologic analysis, Akt activation was correlated with lymph node metastasis in general, but nodal metastasis was correlated with rS6 activation in AC and with mTOR activation in SCC. In conclusion, (i) constitutive activation of EGFR/Akt/mTOR pathway was present in defined subset of NSCLC; (ii) mTOR/S6K/rS6 axis is frequently activated in AC, and constitutively activated through Akt by EGFR mutation even in SCC; and (iii) mTOR and rS6 are possible determinants of nodal metastasis in SCC and AC, respectively.

Diversity of epidermal growth factor receptor-mediated activation of downstream molecules in human lung carcinomas.

The correlations among epidermal growth factor receptor (EGFR) gene amplification, gene mutation, overexpression/phosphorylation of EGFR protein and activation of its downstream molecules, signal transducers and activators of transcription 3 (Stat-3), Akt and extracellular signal-related protein kinase 1/2 (Erk1/2) were investigated in 28 cases of human lung carcinomas. In five cases of carcinomas with EGFR amplification, EGFR expression and phosphorylation levels were higher than other cases, and Stat-3 was activated in all five cases. Point mutations in the tyrosine kinase domain of EGFR were detected in five cases, one of which was also associated with gene amplification. In these five cases, both EGFR expression and phosphorylation were enhanced, and Akt was activated in four cases. In the remaining 19 cases, EGFR protein expression was upregulated in eight cases and phosphorylated in four cases, but neither EGFR nor phosphorylated-EGFR expression levels specifically correlated with activation of particular downstream molecules. In general, either Stat-3 or Akt, but not both, was activated reciprocally and complementarily to each other, as indicated by their phosphorylation. However, Erk1/2 was activated regardless of the status of Stat-3, Akt or EGFR proteins. The current data suggest that persistent Stat-3 activation may be a critical event downstream of EGFR that has been overexpressed by gene amplification. In contrast, tumor cells harboring the EGFR mutation may persistently activate a cascade via Akt. Finally, in the majority of cases that have no aberration of the EGFR, its downstream molecules function in reciprocal and/or complementary manner in the maintenance and/or progression of carcinomas. These overall results could provide novel insights into potential chemotherapeutic regimens for lung carcinomas, such as inhibitors of Stat-3, Akt and Erk1/2.

Differential expression and pathological significance of autocrine motility factor/glucose-6-phosphate isomerase expression in human lung carcinomas

To clarify the involvement of autocrine motility factor (AMF) in the phenotype and biological profiles of human lung carcinomas, we analysed protein and mRNA expression in a total of 180 cases. Immunohistochemistry revealed positive staining in 67.2%, with the highest frequency in squamous cell carcinoma (SCC; 90.8%) and the lowest in small cell carcinoma (SmCC; 27.8%). In SCC, the staining frequency and intensity correlated with the degree of morphological differentiation. Generally, the expression levels in immunoblotting analysis corresponded well with immunohistochemical positivity. However, there was less agreement between protein and mRNA levels: in SmCC and large cell carcinomas (LCCs), mRNA showed higher, but protein showed lower expression. Among non‐small cell lung carcinomas (NSCLCs), AMF protein levels correlated inversely with tumour size, but tumours exhibiting lymph node metastasis showed higher mRNA expression. In cultured lung carcinoma cells which comprised all histological subtypes, AMF was detected in the lysates of all ten cell lines. Secreted AMF protein was detected in the conditioned media from six cell lines, most of which were SmCC or LCC. Thus, a particular subset of lung carcinomas secrete AMF, which may promote cell motility via autocrine stimulation through its cognate receptor and cause the biological aggressiveness seen in SmCC and LCC. Moreover, treatment by proteasome inhibitors resulted in increased cellular AMF in five cell lines, suggesting that intracellular AMF levels are regulated by both secretion and proteasome‐dependent degradation. In conclusion, AMF was detected in a major proportion of lung carcinomas, and may play a part not only in proliferation and/or progression of the tumours, but also, possibly, in the differentiation of SCC. Furthermore, higher mRNA expression may be related to the high metastatic potential of NSCLC and increased protein secretion, leading to a more aggressive phenotype, such as the invasiveness of SmCC and LCC. Copyright

Diverse involvement of isoforms and gene aberrations of Akt in human lung carcinomas

Emerging evidence confirms a central role of Akt in cancer. To evaluate the relative contribution of deregulated Akt and their clinicopathological significance in lung carcinomas, overexpression, activation of Akt and AKT gene increases were investigated. Immunohistochemical staining for 108 cases revealed overexpression of total Akt, Akt1, Akt2 and Akt3 in 61.1, 47.2, 40.7 and 23.1%, respectively, and phosphorylated Akt in 42.6% of cases. Expression of total Akt, Akt2 and Akt3 were frequently observed in small cell carcinoma, but phosphorylated Akt and Akt1 were more frequently observed in squamous cell carcinoma. FISH analysis to evaluate gene increases of AKT1‐3 revealed amplification of AKT1 in 4.2% and AKT1 increase by polysomy of chromosome 14 in 27.3% of cases. For AKT2, amplification was observed in 3.2% and polysomy of chromosome 19 in 26.3% of cases. AKT3 increase was observed in 40.0% of cases only by polysomy of chromosome 1. Although “FISH‐positive” AKT1 and AKT2 gene increases (amplification/high‐level polysomy) were found exclusively in the cases overexpressing total Akt, Akt1 or Akt2, respectively, AKT3 increase was irrelevant of Akt3 expression. Statistically, expressions of Akt2, p‐Akt and cytoplasmic‐p‐Akt were correlated with lymph node metastasis (P = 0.0479, P = 0.0371 and P = 0.0310, respectively). Although AKT1 and AKT2 gene increase showed positive correlation with, or trend towards a positive correlation with tumor size (P = 0.0430, P = 0.0590, respectively), AKT3 did not. In conclusion, Akt isoforms are differentially involved in the pathological phenotype of lung carcinoma in a diverse manner. Because abnormality of Akt1/AKT1 and Akt2/AKT2 correlated with clinicopathological profiles, Akt1/2‐specific targeting may open a novel therapeutic window for the group showing Akt deregulation.

Successful thoracoscopic removal of a giant teratoma following extraction of cystic conponents: A case report

Video‐assisted thoracoscopic surgery is a type of minimal‐access surgery. The nature of the surgery means that there are limitations on the size of a tumor that can be removed through an access incision. Herein, we report our experience removing a giant teratoma (16 × 14 × 13 cm in size) from the anterior mediastinum of a young girl. We employed video‐assisted thoracoscopic surgery to remove the teratoma through a mini‐thoracotomy following the extraction of the cystic components.

Intractable pneumothorax complicated with interstitial pneumonitis treated with the Tachosuture technique: A case report

It has been proven that the Tachosuture technique is effective for preventing prolonged air leaks caused by pulmonary resection. We successfully used the Tachosuture technique to treat intractable pneumothorax with interstitial pneumonia. This technique avoids pulmonary resection and contributes to acute exacerbations of interstitial pneumonia.

Video-assisted thoracoscopic surgery can help enable the complete resection of a mediastinal tumor caused by immunoglobulin G4-related disease and avoid the need for postoperative medication: A case report: VATS for IgG4-related mediastinal tumor

Immunoglobulin (Ig) G4‐related disease has various clinical signs and symptoms, and steroidal therapy with corticosteroids has been found to be effective for treatment. Few cases of IgG4‐related disease associated with paravertebral tumor have been reported, and there have been no reports on complete resection of such a tumor. Here, we report a case of IgG4‐related disease associated with a paravertebral tumor that was successfully resected without the need for postoperative medication. An 84‐year‐old woman was admitted to our hospital with a paravertebral tumor. She underwent thoracoscopic surgery, and pathological examination of the tumor specimen revealed that the tumor resulted from IgG4‐related disease. After resection, there was no need for postoperative medication. Our case indicates the rare possibility of a paravertebral tumor associated with IgG4‐related disease and the potential for complete resection as a treatment for such a tumor.