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Lung cancer remains the most frequent cause of cancer-related death in developed countries. A recent molecular-targeted strategy has contributed to improvement of the remarkable effect of adenocarcinoma of the lung. However, such treatment has not been developed for squamous cell carcinoma (SCC) of the disease. Our recent studies of microRNA (miRNA) expression signatures of human cancers showed that the microRNA-29 family (miR‑29a, miR‑29b and miR‑29c) significantly reduced cancer tissues compared to normal tissues. These findings suggest that miR‑29s act as tumor-suppressors by targeting several oncogenic genes. The aim of the study was to investigate the functional significance of miR‑29s in lung SCC and to identify miR‑29s modulating molecular targets in lung SCC cells. Restoration of all mature members of the miR‑29s inhibited cancer cell migration and invasion. Gene expression data combined in silico analysis and luciferase reporter assays demonstrated that the lysyl oxidase-like 2 (LOXL2) gene was a direct regulator of tumor‑suppressive miR‑29s. Moreover, overexpressed LOXL2 was confirmed in lung SCC clinical specimens, and silencing of LOXL2 inhibited cancer cell migration and invasion in lung SCC cell lines. Our present data suggested that loss of tumor-suppressive miR‑29s enhanced cancer cell invasion in lung SCC through direct regulation of oncogenic LOXL2. Elucidation of the novel lung SCC molecular pathways and targets regulated by tumor-suppressive miR‑29s will provide new insights into the potential mechanisms of oncogenesis and metastasis of the disease.

It has been reported that colon cancer patients with KRAS and BRAF mutations that lie downstream of epidermal growth factor receptor (EGFR) acquire resistance against therapy with anti‑EGFR antibodies, cetuximab and panitumumab. On the other hand, some reports say KRAS codon 13 mutation (p.G13D) has lower resistance against anti-EGFR antibodies, thus there is a substantial need for detection of specific KRAS mutations. We have established a state-of-the-art measurement system using QProbe (QP) method that allows simultaneous measurement of KRAS codon 12/13, p.G13D and BRAF mutation, and compared this method against Direct Sequencing (DS) using 182 specimens from colon cancer patients. In addition, 32 biopsy specimens were processed with a novel pre-treatment method without DNA purification in order to detect KRAS/BRAF. As a result of KRAS mutation measurement, concordance rate between the QP method and DS method was 81.4% (144/177) except for the 5 specimens that were undeterminable. Among them, 29 specimens became positive with QP method and negative with DS method. BRAF was measured with QP method only, and the mutation detection rate was 3.9% (6/153). KRAS measurement using a simple new pre-treatment method without DNA extraction resulted in 31 good results out of 32, all of them matching with the DS method. We have established a simple but highly sensitive simultaneous detection system for KRAS/BRAF. Moreover, introduction of the novel pre-treatment technology eliminated the inconvenient DNA extraction process. From this research achievement, we not only anticipate quick and accurate results returned in the clinical field but also contribution in improving the test quality and work efficiency.

Thymidylate synthase (TS) is a dNTP synthetic enzyme and is also a target enzyme of 5-fluorouracil (5-FU). 5-FU is one of the anticancer agents most frequently used for the treatment of colorectal cancers. However, the clinical rate of response to its use as a single agent is not exceptionally high. Therefore, various combination chemotherapies have been devised. The elevated expression of TS in cancer cells is a serious obstacle in the clinical use of 5-FU. In the present study, TS expression was up-regulated by the knockout of the p21 WAF1/C1P1 gene in human colorectal cancer HCT116 cells, suggesting that TS expression is mediated through the inhibition of cyclin-dependent kinase (CDK). Based on these findings, we tested whether the CDK inhibitor (CDKI) SU9516, acted as a suppressor of TS. SU9516 effectively reduced the expression of TS in a dose-dependent manner Furthermore, the reduction of TS expression resulted in enhancement of the sensitivity to 5-FU in human colon cancer DLD-1 cells. Thus, SU9516 might be a promising compound for combination chemotherapy with 5-FU.

We previously established a bioassay method to screen for compounds that activate the promoter activity of p21 WAF1/CIP1 , a potent inhibitor of cyclin-dependent kinases, in a p53-independent manner. As an activator of p21 WAF1/CIP1 promoter activity, we isolated cryptolepine (CLP: 5-methyl indolo (2,3b)-quiniine), an indoloquinoline alkaloid, from the traditional Ayurvedic medicinal plant Sida cordifolia. We show here that CLP induces the expression of p21 WAF1/CIP1 with growth arrest in p53-mutated human osteosarcoma MG63 cells. Four micromolar of CLP completely inhibited the growth of MG63 cells and caused G 2 /M-phase arrest. CLP up-regulated the expression of p21 WAF1/CIP1 at both mRNA and protein levels in a dose-dependent manner. Using several mutant p21 WAF1/CIP1 promoter constructs, we found that the CLP-responsive element is an Spl site at -82 relative to the transcription start site of the p21 WAF1/CIP1 promoter. These findings suggest that CLP arrests the growth of MG63 cells by activating the p21 WAF1/CIP1 promoter through the specific Spl site in a p53-independent manner. In addition, CLP-mediated cell cycle arrest was reduced by the knockout of the p21 WAF1/CIP1 gene in human colon cancer HCT116 cells, suggesting that the cell cycle arrest by CLP was at least partially mediated through the induction of p21 WAF1/CIP1 expression. Although we need further study of chemotherapeutic effect in vivo, these results raise the possibility that CLP might be a suitable chemotherapeutic agent for treatment of osteosarcoma.