Phosphatidylinositol 3-kinase CB association with preoperative radiotherapy response in rectal adenocarcinoma

Post-diagnosis adiposity and colorectal cancer prognosis: A Global Cancer Update Programme (CUP Global) systematic literature review and meta-analysis

The adiposity influence on colorectal cancer prognosis remains poorly characterised. We performed a systematic review and meta-analysis on post-diagnosis adiposity measures (body mass index [BMI], waist circumference, waist-to-hip ratio, weight) or their changes and colorectal cancer outcomes. PubMed and Embase were searched through 28 February 2022. Random-effects meta-analyses were conducted when at least three studies had sufficient information. The quality of evidence was interpreted and graded by the Global Cancer Update Programme (CUP Global) independent Expert Committee on Cancer Survivorship and Expert Panel. We reviewed 124 observational studies (85 publications). Meta-analyses were possible for BMI and all-cause mortality, colorectal cancer-specific mortality, and cancer recurrence/disease-free survival. Non-linear meta-analysis indicated a reverse J-shaped association between BMI and colorectal cancer outcomes (nadir at BMI 28 kg/m2). The highest risk, relative to the nadir, was observed at both ends of the BMI distribution (18 and 38 kg/m2), namely 60% and 23% higher risk for all-cause mortality; 95% and 26% for colorectal cancer-specific mortality; and 37% and 24% for cancer recurrence/disease-free survival, respectively. The higher risk with low BMI was attenuated in secondary analyses of RCTs (compared to cohort studies), among studies with longer follow-up, and in women suggesting potential methodological limitations and/or altered physiological state. Descriptively synthesised studies on other adiposity-outcome associations of interest were limited in number and methodological quality. All the associations were graded as limited (likelihood of causality: no conclusion) due to potential methodological limitations (reverse causation, confounding, selection bias). Additional well-designed observational studies and interventional trials are needed to provide further clarification.

SP1 Mediated PIK3CB Upregulation Promotes Gastric Carcinogenesis

PIK3CB, one of catalytic subunits of PI3Ks kinase family, is implicated in several cellular processes such as cell growth, proliferation, mobility and neoplastic transformation. Its abnormal expression has been found in several human cancer types. However, the regulation pattern and function of PIK3CB in gastric cancer (GC) are still unclear. Here, we demonstrated that PIK3CB and SP1 (special protein 1) were both upregulated in GC samples compared to adjacent non-cancerous stomach tissues at mRNA and protein levels. The expression of the two genes also displayed a significant positive correlation in GC samples. Dual-luciferase assays and chromatin immunoprecipitation (ChIP) assays revealed that SP1 could bind to the -771~-605 region of the promoter of PIK3CB and enhance transcription. Furthermore, we discovered that SP1 induced AKT activation through PIK3CB and accelerated GC cell proliferation and migration in a PIK3CB/AKT signaling dependent manner. TGX-221, a PIK3CB-selective inhibitor, which can block this signaling transduction pathway, was found to inhibit the growth of GC cells and induce apoptosis in vitro, implying that it may act as a potential development agent for GC. These collective findings provide a new insight into PI3K/AKT signaling that SP1 may function as an upstream factor on PI3K, forming a new signaling axis to promote the progression of GC or other malignancies.

The expression and prognostic significance of PIK3CB in lung adenocarcinoma

OBJECTIVE

The aim of this study was to explore the expression and prognostic significance of PIK3CB in lung adenocarcinoma (LUAD) and to analyse the possible molecular mechanism that promotes LUAD development.

METHODS

Differences of PIK3CB expression at transcriptional level between LUAD and normal tissues were analysed with the Timer and UALCAN databases. Then, immunohistochemical staining was performed to investigate PIK3CB expression at the protein level, and relationships between PIK3CB and clinical characteristics were accessed. Univariate and multivariate Cox regression were performed to identify the independent prognostic risk factors for LUAD. Genetic alterations were analysed using the cBioPortal database. The main coexpressed genes and enrichment pathways of PIK3CB were estimated with the LinkedOmics database.

RESULTS

Compared with normal tissues, PIK3CB was higherly expressed in LUAD at the transcriptional level and protein level, respectively. PIK3CB expression was closely related to prognosis of LUAD patients, and PIK3CB protein expression was associated with lymph node metastasis and pathological differentiation, but not related to sex, age, pleural invasion, vascular invasion, tumour site, tumour size or clinical stage. PIK3CB and tumour size were independent risk factors for LUAD patients. The expression of PIK3CB was negatively correlated with AKT1 and AKT2, but there was no significant correlation with AKT3, and strong positive correlations with ARMC8, DNAJC13 and PIK3R4. The main enrichment pathways of PIK3CB and related genes included adherens junctions and the phosphatidylinositol signalling pathways, ErbB signalling pathways, Hedgehog signalling pathways, and C-type lectin receptor signalling pathways. Therefore, we hypothesized that PIK3CB expression did not promote LUAD development through the classical PI3K/AKT pathway.

CONCLUSION

High PIK3CB expression was associated with the development of LUAD and worse prognosis. PIK3CB was an independent risk factor for LUAD patients. Therefore, this study provides a reliable reference for the prognostic assessment and targeted therapy for LUAD patients.

Nomogram to predict cause-specific mortality of patients with rectal adenocarcinoma undergoing surgery: a competing risk analysis

BACKGROUND

Rectal adenocarcinoma is one of major public health problems, severely threatening people's health and life. Cox proportional hazard models have been applied in previous studies widely to analyze survival data. However, such models ignore competing risks and treat them as censored, resulting in excessive statistical errors. Therefore, a competing-risk model was applied with the aim of decreasing risk of bias and thereby obtaining more-accurate results and establishing a competing-risk nomogram for better guiding clinical practice.

METHODS

A total of 22,879 rectal adenocarcinoma cases who underwent primary-site surgical resection were collected from the SEER (Surveillance, Epidemiology, and End Results) database. Death due to rectal adenocarcinoma (DRA) and death due to other causes (DOC) were two competing endpoint events in the competing-risk regression analysis. The cumulative incidence function for DRA and DOC at each time point was calculated. Gray's test was applied in the univariate analysis and Gray's proportional subdistribution hazard model was adopted in the multivariable analysis to recognize significant differences among groups and obtain significant factors that could affect patients' prognosis. Next, A competing-risk nomogram was established predicting the cause-specific outcome of rectal adenocarcinoma cases. Finally, we plotted calibration curve and calculated concordance indexes (c-index) to evaluate the model performance.

RESULTS

22,879 patients were included finally. The results showed that age, race, marital status, chemotherapy, AJCC stage, tumor size, and number of metastasis lymph nodes were significant prognostic factors for postoperative rectal adenocarcinoma patients. We further successfully constructed a competing-risk nomogram to predict the 1-year, 3-year, and 5-year cause-specific mortality of rectal adenocarcinoma patients. The calibration curve and C-index indicated that the competing-risk nomogram model had satisfactory prognostic ability.

CONCLUSION

Competing-risk analysis could help us obtain more-accurate results for rectal adenocarcinoma patients who had undergone surgery, which could definitely help clinicians obtain accurate prediction of the prognosis of patients and make better clinical decisions.

G-protein coupled receptor 34 regulates the proliferation and growth of LS174T cells through differential expression of PI3K subunits and PTEN

Purpose

G-protein coupled receptor (GPR 34) has been found to play important roles in some cancers and regulates the proliferation, apoptosis, and migration of these cancer cells. However, the mechanisms underlying how GPR34 functions to regulate growth and proliferation of colorectal cancer cells remains to be clarified.

Methods

We employed stable GPR34 knockdown LS174T cell models, GPR34 Mab blocking, a CCK-8 kit, and a colony formation assay to characterize the effect of GPR34 on the proliferation of LS174T in vitro and xenograft tumor growth in vivo. The mRNA level of GPR34 was detected by RT-PCR in tumor tissues and adjacent normal tissues from 34 CRC patients.

Results

Based on RT-PCR results, GPR34 exhibited high level in tumor samples compared with adjacent normal samples. Increased expression of GPR34 is more associated with poor prognosis of CRC as shown in The Cancer Genome Atlas (TCGA) dataset by Kaplan–Meier survival analysis. Furthermore, we showed that GPR34 knockdown inhibited the proliferation of LS174T colon cancer cells and related xenograft tumor growth. Searching for the distinct molecular mechanism, we identified several contributors to proliferation of LS174T colon cancer cells: PI3K subunits/PTEN, PDK1/AKT, and Src/Raf/Ras/ERK. GPR34 knockdown inhibited the proliferation of LS174T cells by upregulating expression of PTEN, and downregulating expression of PI3K subunits p110-beta.

Conclusion

Our findings provide direct evidence that GPR34 regulates the proliferation of LS174T cells and the growth of LS174T tumor xenografts by regulating different pathways. High expression of GPR34 mRNA could then be used to predict poor prognosis of CRC.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11033-021-07068-4.

Current status of surgical treatment of rectal cancer in China

With the changing lifestyle and the acceleration of aging in the Chinese population, the incidence and mortality of colorectal cancer (CRC) have risen in the last decades. On the contrary, the incidence and mortality of CRC have continued to decline in the USA since the 1980s, which is mainly attributed to early screening and standardized diagnosis and treatment. Rectal cancer accounts for the largest proportion of CRC in China, and its treatment regimens are complex. At present, surgical treatment is still the most important treatment for rectal cancer. Since the first Chinese guideline for diagnosis and treatment of CRC was issued in 2010, the fourth version has been revised in 2020. These guidelines have greatly promoted the standardization and internationalization of CRC diagnosis and treatment in China. And with the development of comprehensive treatment methods such as neoadjuvant chemoradiotherapy, targeted therapy, and immunotherapy, the post-operative quality of life and prognosis of patients with rectal cancer have improved. We believe that the inflection point of the rising incidence and mortality of rectal cancer will appear in the near future in China. This article reviewed the current status and research progress on surgical therapy of rectal cancer in China.

PI3Kβ-A Versatile Transducer for GPCR, RTK, and Small GTPase Signaling

The phosphoinositide 3-kinase (PI3K) family includes eight distinct catalytic subunits and seven regulatory subunits. Only two PI3Ks are directly regulated downstream from G protein-coupled receptors (GPCRs): the class I enzymes PI3Kβ and PI3Kγ. Both enzymes produce phosphatidylinositol 3,4,5-trisposphate in vivo and are regulated by both heterotrimeric G proteins and small GTPases from the Ras or Rho families. However, PI3Kβ is also regulated by direct interactions with receptor tyrosine kinases (RTKs) and their tyrosine phosphorylated substrates, and similar to the class II and III PI3Ks, it binds activated Rab5. The unusually complex regulation of PI3Kβ by small and trimeric G proteins and RTKs leads to a rich landscape of signaling responses at the cellular and organismic levels. This review focuses first on the regulation of PI3Kβ activity in vitro and in cells, and then summarizes the biology of PI3Kβ signaling in distinct tissues and in human disease.

Intra-hydrogel culture prevents transformation of mesenchymal stem cells induced by monolayer expansion

In this study, we report that the intra-hydrogel culture system mitigates the transformation of mesenchymal stem cells (MSCs) induced by two-dimensional (2D) expansion. MSCs expanded in monolayer culture prior to encapsulation in collagen hydrogels (group eMSCs-CH) featured impaired stemness in chondrogenesis, comparing with the freshly isolated bone marrow mononuclear cells seeded directly in collagen hydrogels (group fMSCs-CH). The molecular mechanism of the in vitro expansion-triggered damage to MSCs was detected through genome-wide microarray analysis. Results indicated that pathways such as proteoglycans in cancer and pathways in cancer expansion were highly enriched in eMSCs-CH. And multiple up-regulated oncoma-associated genes were verified in eMSCs-CH compared with fMSCs-CH, indicating that expansion in vitro triggered cellular transformation was associated with signaling pathways related to tumorigenicity. Besides, focal adhesion (FA) and mitogen-activated protein kinase (MAPK) signaling pathways were also involved in in vitro expansion, indicating restructuring of the cell architecture. Thus, monolayer expansion in vitro may contribute to vulnerability of MSCs through the regulation of FA and MAPK. This study indicates that intra-hydrogel culture can mitigate the monolayer expansion induced transformation of MSCs and maintain the uniformity of the stem cells, which is a viable in vitro culture system for stem cell therapy.